Photophysical Behaviour of Novel Quaternary Pyrenoyl Salts and Their Sensitivity Towards Bile Salt Micellization

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Saravanan, S. Dhivakar, M. Mohapatra, S. Kutti Rani, K. Vijayakumaran This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1308526/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 4 You are reading this latest preprint version Abstract The present work describes the synthesis and characterization of pyrene derivatives, N-(1-Pyrenoylmethyl)pyridinium bromide (PM-PB) and N-(1-Pyrenoylmethyl)-N,N,N-triethylammonium bromide (PM-TAB). Photophysical behavior of these molecules has been studied in various protic and aprotic solvents. Using steady state fluorescence intensity, fluorescence anisotropy and dynamic fluorescence lifetime studies, the sensitivity of these molecules towards the micellization process of bile salts has been monitored. These derivatives have been effectively used in estimating critical micellar concentration (CMC) of bile salt, sodium deoxycholate (NaDC). Pyrenoyl salts Bile salt Micellization Sodium deoxycholate Fluorescence Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 1. Introduction Pyrene is an interesting fluorescent molecule for preparing organic electronic materials. 1 Over the past decade, many pyrene-based dyes have been synthesized, and their photophysical properties have been studied [ 1 – 4 ]. Fluorescence of pyrene derivatives always has potential application in studying organized and microheterogeneous media [ 3 , 4 ]. The photophysical properties of pyrenecarbonyl compounds like 1-methoxycarbonylpyrene, 1-acetylpyrene, pyrene-3-carboxaldehyde, 1-pyrenecarboxylic acid, are well known and have widely been used in various fields [ 1 ]. Polarity sensitive, sparingly soluble fluorophore pyrene-3-carboxaldehyde and pH sensitive 1-Pyrenecarboxylic acid makes them useful derivatives of pyrene [ 1 , 5 – 7 ]. The understanding of photophysical properties of carbonyl functionalized pyrenes is essential for material design and for expanding the scope of their applications. Physiological importance of bile salts lies in their potentiality to solubilize fat soluble vitamins, cholesterol, and lipids in the hepatobiliary ststems [ 8 – 10 ]. These biosurfactants have obtained much recognition due to their application in delivery systems for medicines, cosmetics etc. Bile salts at their lower concentrations are known to hydrate the lipid bilayer membranes [ 11 – 13 ]. Micelle forming ability of bile salts is due to the presence of hydrophobic and hydrophilic parts in the same molecule. Micellization process brings about several changes in a surfactant solution. This results in appreciable alteration in surface tension, viscosity, light scattering phenomenon etc., which makes the basis of several analytical techniques for the investigation of micelle formation [ 14 – 18 ]. For monitoring biological activities of bile salts the critical micelle concentration (CMC) is an important fundamental parameter. Over the years, fluorescence spectroscopy has been used as an important technique to study the CMC of bile salts [ 4 , 18 – 21 ]. The main objectives of the present work are (i) synthesis and characterization of the carbonyl functionalized pyrene derivatives, N-(1-Pyrenoylmethyl)pyridinium bromide (PM-PB) and N-(1-Pyrenoylmethyl)-N,N,N-triethylammonium bromide (PM-TAB); (ii) detailed photophysical investigations of the synthesized molecules in homogeneous media; (iii) sensitivity of these molecules towards micellization process of bile salt, sodium deoxycholate (NaDC). 2. Materials And Methods 2.1. Materials N-(1-Pyrenoylmethyl)pyridinium bromide (PM-PB) and N-(1-Pyrenoylmethyl)-N,N,N-triethylammonium (PM-TAB) were synthesized and purified by repeated recrystrallization Reagent grade chemicals were used and solvents were purified by standard techniques. Melting points were determined using Vego digital programmable melting point device. Thin Layer Chromatography (TLC) was carried out using Merck aluminum TLC plates, silica gel coated with flourescent indicator F254. HPLC analysis was performed using Waters Alliance 2695 instrument with PDA 2998 detector. Bile salt; sodium deoxycholate (NaDC) was obtained from S.D. Fine Chemicals Ltd. For the photophysical study all solvents used were of spectroscopic grade. Triple distilled water, purified using KMnO 4 and NaOH, was used for the preparation of bile salt solution. 2.2. Sample preparation for photophysical studies The stock solutions (10 −3 M) of pyrene derivatives were prepared in methanol. The solutions in all other solvents were prepared by evaporating the methanol from the desired amount of the stock by gentle purging of nitrogen gas and then sonicating it with the solvent of interest. A set of NaDC solutions in the concentrations range of 1–18 mM containing the same amount of pyrene derivatives (5 × 10 −5 M), was prepared in water at neutral pH. The synthesized compounds are quite insoluble in water. All these experiments were carried out at room temperature. 2.3. Absorption and steady state fluorescence experiments Absorption spectra were collected using a Jasco V-650 UV-Vis spectrometer. Steady state fluorescence intensity and fluorescence anisotropy measurements were carried out using a Horiba Jobin–Yvon FluoroMax-4 spectrofluorimeter, with a 150 W xenon lamp as the light source. The emission spectra and fluorescence anisotropy were recorded with slit widths of 3/3 nm. The excitation wavelength was fixed at 370 nm. 2.4. Fluorescence lifetime measurements Fluorescence decay dynamic studies were carried out using Horiba Jobin Yvon TCSPC lifetime instrument in a time-correlated, single photon counting arrangement. 370 nm nano-LED was used as the light source. The instrument response function was collected using a scatterer (Ludox AS40 colloidal silica). The decay data were analyzed using IBH software. A value of χ2 of 0.99 ≥ χ2 ≤ 1.3 was considered as a good fit which was further confirmed by the symmetrical distribution of the residuals. 3. Results And Discussion 3.1. Synthesis and Characterization of Pyrene derivatives 3.1.1. 1-Acetylpyrene [ 22 ] To nitrobenzene (redistilled, 700 ml), aluminium chloride (anhydrous, 140 g, 1.05 mole), acetic anhydride (50 ml. 0.53 mole) were added under stirring and cooled to 10 deg C. Then, pyrene (recrystallized from acetone, 100 g, 0.49 mole) was added over a period of 30 minutes, under stirring. After 6 hours the reaction was complete and the contents were poured into ice water (2 x 150 ml) and conc. HCl (70 ml) and layers separated. The reaction was monitored by Thin layer chromatography (TLC). Nitrobenzene was removed by steam distillation The green-coloured crude product (140 g) was recrystallized from hot isopropanol. Yield: 85 g (yellow crystals, 71%). MP: 87-89 deg C (86-89 deg C) [ 22 ] 3.1.2. 1-(Bromoacetyl)pyrene [ 23 – 25 ] 1-Acetylpyrene (10.0 g, 0.04 m) was dissolved in tetrahydrofuran(THF) (redistilled and dried, 250 ml). Then phenyltrimethylammonium tribromide (16.0 g, 0.043 m) was added under magnetic stirring for 3 hours at ambient temperature. The reaction was monitored by TLC. The crystalline precipitate (phenyltrimethylammonium bromide) was filtered and the solvent was concentrated under reduced pressure. The orange coloured crude product (16.0 g) was recrystallised from hot benzene. Yield: 11.2 g (yellow crystals, 85.5%). MP. 133-135 deg C (128-129 deg C) [ 26 ] 3.1.3. N-(1-Pyrenoylmethyl)pyridinium bromide [ 27 ] To acetonitile (25 ml, reagent grade) were added 1-(bromoacetyl)pyrene (5.0 g, 0.015 m) and pyridine (redistilled, 1.3 ml, 0.016 m) and heated to reflux for 6 hours in an oil bath and the reaction monitored by TLC. The yellow solid formed was filtered and washed with hot benzene to afford the crude yellow powder (6.0 g) which was recrystallised from redistilled N,N-Dimethylformamide. Yield: 5.1 g (yellow powder, 84.5.%). MP: 276-279 deg C (decomp.); purity: 99.98% (High performance liquid chromatography (HPLC)) 3.1.4. N-(1-Pyrenoylmethyl)-N,N,N-triethylammonium bromide [ 28 ] To acetonitile (50 ml, reagent grade) were added 1-(bromoacetyl)pyrene (2.0 g, 0.006 m) and triethylamine (redistilled, 1.5 ml, 0.011 m) and heated to reflux for 6 hours in an oil bath and the reaction monitored by TLC. The yellow solid formed was filtered and washed with hot benzene to afford the crude yellow powder (2 g) which was recrystallised from redistilled acetonitrile. Yield: 1.6 g (orange powder, 62.8%). MP: 217-219 deg C (decomp.); purity: 97.74% (HPLC) The synthesized pyrene derivatives N-(1-Pyrenoylmethyl)pyridinium bromide (PM-PB) and N-(Pyrenoylmethyl)triethyl ammonium bromide (PM-TAB) are shown in Fig. 1. 3.2. Photophysical studies of PM-PB and PM-TAB in homogeneous media 3.2.1. Absorption Studies: Figure 2 A and B represents the UV-Vis absorption spectra of PM-PB and PM-TAB in solvents of varying polarity, respectively. The absorption spectra of both the molecules extended well into the visible region. The absorption spectra of N-(1-Pyrenoylmethyl) pyridinium bromide (PM-PB) do not change much with solvents of different polarity. This indicates within the short time scale (10 −15 s) of the absorption phenomenon, PM-PB is insensitive to the solvent microenvironment around it. In the same set of solvents, the absorption spectrum of PM-TAB was also recorded. It has been observed that on changing solvent polarity PM-TAB shows almost similar absorption features as that of PM-PB. In both the case there is not much change in the energy of transition in different solvents, which implies that stabilization of the ground state species of the compounds by the solvents is not significant. 3.2.2. Steady State Fluorescence Studies: Figure 3 A and B shows the normalized steady state fluorescence spectra of PM-PB and PM-TAB in various solvents of different polarity, respectively. Fig. S1 in the supporting information shows the emission spectra of PM-PB and PM-TAB without normalization indifferent solvents. With increase in solvent polarity from heptane to water, there is a negligible red shift of ~10 nm in the spectral profile of PM-PB. In non-interacting solvents (like heptane and cyclohexane) the emission spectra of PM-PB and PM-TAB are more structured as compared to that in other solvents of moderate and high polarity. However, PM-TAB shows a remarkable red shift of ~50 nm in its emission spectral profile with increase in solvent polarity. Both the molecules are not completely soluble in water and showed a very weak fluorescence (Fig. S1 in the supporting information). The Stokes shift of PM-PB and PM-TAB fits well with ET(30) scales of solvent polarity (Fig. 4 ) [ 2 , 29 ]. ET (30) scale is the popularly used solvatochromic scale in the literature. It represents the transition energy in kcal mol −1 for the longest wavelength absorption band of the dissolved pyridinium-N-phenoxide betaine dye. Correlation of solvent-dependent properties with the ET(30) scale often follows two distinct lines, one for the aprotic and another for the protic solvents. In the present case, ET (30) plot for PM-PB and PM-TAB shows two different slopes corresponding to aprotic and protic solvents. 3.3. Interaction of PM-PB and PM-TAB with bile salt (NaDC) 3.3.1. Steady State Fluorescence Intensity and Anisotropy Studies: The variation of fluorescence intensity of PM-PB and PM-TAB with concentration of NaDC is shown in Fig. S2 in the supporting information. The corresponding plot of fluorescence intensity of PM-PB and PM-TAB with NaDC concentration has been given in Fig. 5 A and B, respectively. With the concentration of NaDC, fluorescence intensity of both the molecules shows a sigmoid variation. The CMC point has been represented by the point of intersection of the horizontal line and the line of inflation (shown as dashed lines in Fig. 5 A and B). It is found to be 5 mM for NaDC. This is in agreement with the reported values range from 2–10mM for NaDC [ 4 , 18 – 21 ]. With increase in NaDC concentration, a remarkable increase in the fluorescence intensity of PM-PB and PM-TAB suggests that hydrophobic bile salt micellar aggregates provides a solubilizing environment to the molecules. In an organized media, the fluorescence anisotropy of a fluorescent molecule indicates the resistance offered by the microenvironment to its rotational movement. Hence, the change in the polarization of PM-PB and PM-TAB fluorescence acts as an index for the change in microviscosity of the immediate environment [ 3 , 4 , 13 ]. Fig. 6 A and B represents the plots for the variation of steady state fluorescence anisotropy of PM-PB and PM-TAB as a function of NaDC concentration. Increase in fluorescence anisotropy with increasing NaDC concentration indicates restricted rotational mobility of PM-PB and PM-TAB in the progressive bile salt micellar environment. 3.3.2. Fluorescence Lifetime Studies: Time resolved fluorescence decay studies have been performed to have a better understanding of the sensitivity of PM-PB and PM-TAB towards micellar aggregation of NaDC. Both the molecules show bi-exponential decay profile in presence and absence of NaDC (Fig. 7 ). The lifetime values of PM-PB and PM-TAB with increasing NaDC concentration has been given in Table 1 . Unlike pyrene, there molecules show short lifetime values. Table 1. Fluorescence lifetime values of(A) PM-PB and (B) PM-TAB with increasing NaDC concentration from 0to 18 mM. (λ ex = 370 nm, λ em = 450 nm) (A) [NaDC] (mM) t s (ns), (a 1 ) t l (ns), (a 2 ) t avg (ns) c 2 0 0.14 (25) 5.29 (75) 5.24 1.18 1 0.17 (23) 5.41 (77) 5.36 1.10 3 0.81 (28) 5.13 (72) 4.88 1.43 4 1.02 (54) 5.20 (46) 4.42 1.41 5 1.50 (87) 4.84 (13) 2.59 1.36 6 1.56 (90) 4.88 (10) 2.42 1.22 7 1.60 (90) 4.78 (10) 2.39 1.24 8 1.62 (91) 5.07 (09) 2.43 1.24 10 1.64 (90) 4.73 (10) 2.39 1.32 14 1.62 (88) 4.30 (12) 2.33 1.38 18 1.61 (87) 4.14 (13) 2.31 1.34 (B) [NaDC] (mM) t s (ns), (a 1 ) t l (ns), (a 2 ) t avg (ns) c 2 0 0.68 (57) 4.12 (43) 3.50 1.15 1 0.69 (59) 4.04 (41) 3.38 1.23 3 0.69 (57) 3.86 (43) 3.25 1.12 4 0.70 (62) 3.91 (38) 3.18 1.41 5 0.71 (78) 3.01 (22) 1.96 1.15 6 0.74 (76) 2.93 (24) 1.96 1.14 7 0.78 (83) 2.95 (17) 1.73 0.97 8 0.84 (81) 2.86 (19) 1.72 0.95 10 0.95 (79) 2.74 (21) 1.73 0.97 14 1.00 (81) 2.77 (19) 1.70 0.97 18 1.17 (84) 2.53 (16) 1.57 0.97 In water medium, due to poor solubility of PM-PB and PM-TAB there may be presence of small aggregates of the molecules along with the monomeric forms. This may be responsible for the biexponential decay of PM-PB and PM-TAB in water with a shorter and longer lifetime component. The monomeric form is expected to have a shorter lifetime value while the aggregated form to have longer lifetime. The amplitudes (a 1 , a 2 ) of the corresponding components, indicates the population of the respective components in their microenvironment. Amid a progressive formation of bile salt micellar aggregates on increasing NaDC concentration, there is an increase in amplitude and lifetime of the monomeric form. This may be due to the breaking of aggregated forms of PM-PB and PM-TAB in presence of bile salt and corresponding incorporation of the monomeric forms in to the NaDC micellar aggregates. In other words, there is an increase in solubility of PM-PB and PM-TAB with NaDC concentration. As compared to PM-TAB the variation is more prominent in case of PM-PB. Conclusions The synthesis and characterization of pyrene derivatives, N-(1-Pyrenoylmethyl)pyridinium bromide (PM-PB) and N-(1-Pyrenoylmethyl)-N,N,N-triethylammonium (PM-TAB) were discussed. With increase in solvent polarity from heptane to water, there is a negligible red shift of ~10 nm in the spectral profile of PM-PB. However, PM-TAB shows a reasonable red shift of ~50 nm in its emission spectral profile. The Stokes shift of PM-PB and PM-TAB fits well with ET (30) scale of solvent polarity. The steady state fluorescence intensity and dynamic fluorescence lifetime of these derivatives were found to be sensitive to the NaDC micellar aggregates. Present study provides a basic photophysical understanding of PM-PB and PM-TAB in the absence and presence of physiologically important bile salts. Declarations ACKNOWLEDGMENTS: The authors thank Prof. K. K. Balasubramanian and Prof A. K. Mishra of IIT Madras, India, for their valuable discussion and help in collecting fluorescence lifetime data. AUTHOR DECLARATIONS: Funding There are currently no funding sources. Conflicts of interest There are no conflicts to declare. Ethical Approval All authors declare Ethics approval. Consent to Participate All authors Consent to participate. Consent for Publication All authors Consent for publication. Data Availability All the data that have been referred to in the manuscript without being included have been given in the Supporting Information. Figures showing emission spectra of PM-PB and PM-TAB in solvents of different polarity (Fig. S1), emission spectra of PM-PB and PM-TAB with increasing NaDC concentration from 0 to 18 mM (Fig. S2) are available in the supporting information. Code Availability Not applicable. Authors' contributions Synthesis, chemical characterization has been done by MS, SD, and supervised by SKR, and KV. Photophysical studies has been done by MS, MM, and supervised by MM. All authors read and approved the final manuscript. References Niko Y, Hiroshige Y, Kawauchi S, Konishi G (2012) Tetrahedron, 68, 6177–6185 and reference their in Subuddhi U, Haldar S, Sankararaman S, Mishra AK (2006) Photochemical and Photobiological Sciences 5:459–466 Subuddhi U, Haldar S, Sankararaman S, Mishra AK (2008) J Photochem Photobiol A 200:381–387 Sarkar I, Hemamalini A, Das TM, Mishra AK (2016) RSC Adv 6:27933–27943 Milosavljevic BH, Thomas JK (1988) J Phys Chem 92:2997–3001 Su FK, Liau GF, Hong JL (2007) J Polym Sci Part B Polym Phys 45:920–929 Miller E, Styczynska DJ (2009) Spectrochimica Acta Part A 72:312–321 Coleman R (1987) Bile salts and biliary lipids. Kenneth S. Dodgson memorial symposium, Biochem. Soc. Trans., 15, S68–S89 Notter RH (2000) Lung Surfactants: Basic Science and Clinical Applications. 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Chem, 19873, 48,3577–3580 Avijit Jana S, Atta SK, Sarkar ND, Pradeep Singh (2010) Tetrahedron 66:9798–9807 Anuradha M (2007) Swati. Colloid Polym Sci 285:397–404 Jacques J, Marquet A (1973) Org Synthesis 53:111 Nynke M, van Spijker AM, Cornelisse J (1990) J. Org. Chem., 55, 756-758 Gridin VV, Kim TK, Bekkerman A, Bulatov V, Jung K-H, chechtera I (2003) Eur J Mass Spectrosc 9:187 Songjie Yu S, Liu Yu, Lan B Van (2015) J Am Chem Soc 137:1623–1631XingweiLi Marcus Y (1991) J Solut Chem 20:929–944 Supplementary Files Supporting.docx Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 06 Feb, 2022 Reviewers invited by journal 04 Feb, 2022 Editor assigned by journal 02 Feb, 2022 First submitted to journal 28 Jan, 2022 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-1308526","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":81562325,"identity":"4dbf97e0-852c-4c2b-bcd3-7bd6f5bedc97","order_by":0,"name":"M. 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(Concentration of PM-PB and PM-TAB = 5 × 10\u003csup\u003e-5\u003c/sup\u003eM).\u0026nbsp;\u003c/p\u003e","description":"","filename":"fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-1308526/v1/92ece98045a25b079d0e9be5.png"},{"id":18003473,"identity":"971c5083-0dea-45b3-bf9e-7d04de1e2089","added_by":"auto","created_at":"2022-02-07 17:27:33","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":177360,"visible":true,"origin":"","legend":"\u003cp\u003eNormalized emission spectra of (A) PM-PB and (B) PM-TAB in solvents of different polarity. (Concentration of PM-PB and PM-TAB= 5 × 10\u003csup\u003e-5\u003c/sup\u003eM, λ\u003csub\u003eex \u003c/sub\u003e= 370 nm).\u003c/p\u003e\u003cp\u003e\u003cbr\u003e\u003c/p\u003e","description":"","filename":"fig3.png","url":"https://assets-eu.researchsquare.com/files/rs-1308526/v1/efaef1b20a6a8056714ba1fd.png"},{"id":18003474,"identity":"35c74a71-f20c-4475-9cca-5b809a8fa195","added_by":"auto","created_at":"2022-02-07 17:27:33","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":100638,"visible":true,"origin":"","legend":"\u003cp\u003eET(30) plot for (A) PM-PB and (B) PM-TAB.\u003c/p\u003e","description":"","filename":"fig4.png","url":"https://assets-eu.researchsquare.com/files/rs-1308526/v1/751237681e04931d403436e3.png"},{"id":18003476,"identity":"d298223f-84b1-4558-b7f8-c33d0c80ca53","added_by":"auto","created_at":"2022-02-07 17:27:33","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":81309,"visible":true,"origin":"","legend":"\u003cp\u003ePlots of variation in steady state fluorescence intensity of (A) PM-PB and (B) PM-TAB with increasing NaDC concentration from 0to 18 mM. (Concentration of PM-PB and PM-TAB = 5 × 10\u003csup\u003e-5\u003c/sup\u003eM,λ\u003csub\u003eex \u003c/sub\u003e= 370 nm).\u003c/p\u003e\u003cp\u003e\u003cbr\u003e\u003c/p\u003e","description":"","filename":"fig5.png","url":"https://assets-eu.researchsquare.com/files/rs-1308526/v1/169bb04008f6803bbf4f004d.png"},{"id":18003475,"identity":"429b2c3b-2fd8-495a-a400-7c709bedbf67","added_by":"auto","created_at":"2022-02-07 17:27:33","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":74753,"visible":true,"origin":"","legend":"\u003cp\u003ePlots of variation in steady state fluorescence anisotropy of (A) PM-PB and (B) PM-TAB with increasing NaDC concentration from 0 to 18 mM.\u003c/p\u003e\u003cp\u003e\u003cbr\u003e\u003c/p\u003e","description":"","filename":"fig6.png","url":"https://assets-eu.researchsquare.com/files/rs-1308526/v1/c18a663513f08abd423dc468.png"},{"id":18003479,"identity":"f1ea48e4-33c1-4c1b-8ac0-afab6629eddb","added_by":"auto","created_at":"2022-02-07 17:27:33","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":171052,"visible":true,"origin":"","legend":"\u003cp\u003eDecay profile of (A) PM-PB and (B) PM-TAB with increasing NADC concentration from 0 to 18 mM. (λ\u003csub\u003eex \u003c/sub\u003e= 370 nm, λ\u003csub\u003eem\u003c/sub\u003e= 450 nm)\u003c/p\u003e\u003cp\u003e\u003cbr\u003e\u003c/p\u003e","description":"","filename":"fig7.png","url":"https://assets-eu.researchsquare.com/files/rs-1308526/v1/f089d182febe86db428b0a9a.png"},{"id":18003920,"identity":"6e12797e-7d5d-4acb-bd75-c733a54125a4","added_by":"auto","created_at":"2022-02-07 17:30:36","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1055407,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-1308526/v1/35d255dd-c0a5-4c30-a493-3508b8ecaf11.pdf"},{"id":18003478,"identity":"85049dfc-b757-4f5c-b67b-cd5aaa60cc53","added_by":"auto","created_at":"2022-02-07 17:27:33","extension":"docx","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":350701,"visible":true,"origin":"","legend":"","description":"","filename":"Supporting.docx","url":"https://assets-eu.researchsquare.com/files/rs-1308526/v1/5e4961e25bfe685f7386e58a.docx"}],"financialInterests":"","formattedTitle":"\u003cp\u003ePhotophysical Behaviour of Novel Quaternary Pyrenoyl Salts and Their Sensitivity Towards Bile Salt Micellization\u003c/p\u003e","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003ePyrene is an interesting fluorescent molecule for preparing organic electronic materials.\u003csup\u003e1\u003c/sup\u003eOver the past decade, many pyrene-based dyes have been synthesized, and their photophysical properties have been studied [\u003cspan additionalcitationids=\"CR2 CR3\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Fluorescence of pyrene derivatives always has potential application in studying organized and microheterogeneous media [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. The photophysical properties of pyrenecarbonyl compounds like 1-methoxycarbonylpyrene, 1-acetylpyrene, pyrene-3-carboxaldehyde, 1-pyrenecarboxylic acid, are well known and have widely been used in various fields [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Polarity sensitive, sparingly soluble fluorophore pyrene-3-carboxaldehyde and pH sensitive 1-Pyrenecarboxylic acid makes them useful derivatives of pyrene [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan additionalcitationids=\"CR6\" citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. The understanding of photophysical properties of carbonyl functionalized pyrenes is essential for material design and for expanding the scope of their applications.\u003c/p\u003e \u003cp\u003ePhysiological importance of bile salts lies in their potentiality to solubilize fat soluble vitamins, cholesterol, and lipids in the hepatobiliary ststems [\u003cspan additionalcitationids=\"CR9\" citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. These biosurfactants have obtained much recognition due to their application in delivery systems for medicines, cosmetics etc. Bile salts at their lower concentrations are known to hydrate the lipid bilayer membranes [\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e]. Micelle forming ability of bile salts is due to the presence of hydrophobic and hydrophilic parts in the same molecule. Micellization process brings about several changes in a surfactant solution. This results in appreciable alteration in surface tension, viscosity, light scattering phenomenon etc., which makes the basis of several analytical techniques for the investigation of micelle formation [\u003cspan additionalcitationids=\"CR15 CR16 CR17\" citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. For monitoring biological activities of bile salts the critical micelle concentration (CMC) is an important fundamental parameter. Over the years, fluorescence spectroscopy has been used as an important technique to study the CMC of bile salts [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan additionalcitationids=\"CR19 CR20\" citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe main objectives of the present work are (i) synthesis and characterization of the carbonyl functionalized pyrene derivatives, N-(1-Pyrenoylmethyl)pyridinium bromide (PM-PB) and N-(1-Pyrenoylmethyl)-N,N,N-triethylammonium bromide (PM-TAB); (ii) detailed photophysical investigations of the synthesized molecules in homogeneous media; (iii) sensitivity of these molecules towards micellization process of bile salt, sodium deoxycholate (NaDC).\u003c/p\u003e"},{"header":"2. Materials And Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Materials\u003c/h2\u003e \u003cp\u003eN-(1-Pyrenoylmethyl)pyridinium bromide (PM-PB) and N-(1-Pyrenoylmethyl)-N,N,N-triethylammonium (PM-TAB) were synthesized and purified by repeated recrystrallization Reagent grade chemicals were used and solvents were purified by standard techniques. Melting points were determined using Vego digital programmable melting point device. Thin Layer Chromatography (TLC) was carried out using Merck aluminum TLC plates, silica gel coated with flourescent indicator F254. HPLC analysis was performed using Waters Alliance 2695 instrument with PDA 2998 detector. Bile salt; sodium deoxycholate (NaDC) was obtained from S.D. Fine Chemicals Ltd. For the photophysical study all solvents used were of spectroscopic grade. Triple distilled water, purified using KMnO\u003csub\u003e4\u003c/sub\u003e and NaOH, was used for the preparation of bile salt solution.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Sample preparation for photophysical studies\u003c/h2\u003e \u003cp\u003eThe stock solutions (10\u003csup\u003e\u0026minus;3\u003c/sup\u003e M) of pyrene derivatives were prepared in methanol. The solutions in all other solvents were prepared by evaporating the methanol from the desired amount of the stock by gentle purging of nitrogen gas and then sonicating it with the solvent of interest. A set of NaDC solutions in the concentrations range of 1\u0026ndash;18 mM containing the same amount of pyrene derivatives (5 \u0026times; 10\u003csup\u003e\u0026minus;5\u003c/sup\u003eM), was prepared in water at neutral pH. The synthesized compounds are quite insoluble in water. All these experiments were carried out at room temperature.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Absorption and steady state fluorescence experiments\u003c/h2\u003e \u003cp\u003eAbsorption spectra were collected using a Jasco V-650 UV-Vis spectrometer. Steady state fluorescence intensity and fluorescence anisotropy measurements were carried out using a Horiba Jobin\u0026ndash;Yvon FluoroMax-4 spectrofluorimeter, with a 150 W xenon lamp as the light source. The emission spectra and fluorescence anisotropy were recorded with slit widths of 3/3 nm. The excitation wavelength was fixed at 370 nm.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Fluorescence lifetime measurements\u003c/h2\u003e \u003cp\u003eFluorescence decay dynamic studies were carried out using Horiba Jobin Yvon TCSPC lifetime instrument in a time-correlated, single photon counting arrangement. 370 nm nano-LED was used as the light source. The instrument response function was collected using a scatterer (Ludox AS40 colloidal silica). The decay data were analyzed using IBH software. A value of χ2 of 0.99\u0026thinsp;\u0026ge;\u0026thinsp;χ2 \u0026le; 1.3 was considered as a good fit which was further confirmed by the symmetrical distribution of the residuals.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results And Discussion","content":"\u003cdiv class=\"Section2\" id=\"Sec8\"\u003e\n \u003ch2\u003e3.1. Synthesis and Characterization of Pyrene derivatives\u003c/h2\u003e\n \u003cdiv class=\"Section3\" id=\"Sec9\"\u003e\n \u003ch2\u003e3.1.1. 1-Acetylpyrene [\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/h2\u003e\n \u003cp\u003eTo nitrobenzene (redistilled, 700 ml), aluminium chloride (anhydrous, 140 g, 1.05 mole), acetic anhydride (50 ml. 0.53 mole) were added under stirring and cooled to 10 deg C. Then, pyrene (recrystallized from acetone, 100 g, 0.49 mole) was added over a period of 30 minutes, under stirring. After 6 hours the reaction was complete and the contents were poured into ice water (2 x 150 ml) and conc. HCl (70 ml) and layers separated. The reaction was monitored by Thin layer chromatography (TLC). Nitrobenzene was removed by steam distillation The green-coloured crude product (140 g) was recrystallized from hot isopropanol.\u003c/p\u003e\n \u003cp\u003eYield: 85 g (yellow crystals, 71%).\u003c/p\u003e\n \u003cp\u003eMP: 87-89 deg C (86-89 deg C) [\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e]\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Section3\" id=\"Sec10\"\u003e\n \u003ch2\u003e3.1.2. 1-(Bromoacetyl)pyrene [\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e25\u003c/span\u003e]\u003c/h2\u003e\n \u003cp\u003e1-Acetylpyrene (10.0 g, 0.04 m) was dissolved in tetrahydrofuran(THF) (redistilled and dried, 250 ml). Then phenyltrimethylammonium tribromide (16.0 g, 0.043 m) was added under magnetic stirring for 3 hours at ambient temperature. The reaction was monitored by TLC. The crystalline precipitate (phenyltrimethylammonium bromide) was filtered and the solvent was concentrated under reduced pressure. The orange coloured crude product (16.0 g) was recrystallised from hot benzene.\u003c/p\u003e\n \u003cp\u003eYield: 11.2 g (yellow crystals, 85.5%).\u003c/p\u003e\n \u003cp\u003eMP. 133-135 deg C (128-129 deg C) [\u003cspan class=\"CitationRef\"\u003e26\u003c/span\u003e]\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Section3\" id=\"Sec11\"\u003e\n \u003ch2\u003e3.1.3. N-(1-Pyrenoylmethyl)pyridinium bromide [\u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e]\u003c/h2\u003e\n \u003cp\u003eTo acetonitile (25 ml, reagent grade) were added 1-(bromoacetyl)pyrene (5.0 g, 0.015 m) and pyridine (redistilled, 1.3 ml, 0.016 m) and heated to reflux for 6 hours in an oil bath and the reaction monitored by TLC. The yellow solid formed was filtered and washed with hot benzene to afford the crude yellow powder (6.0 g) which was recrystallised from redistilled N,N-Dimethylformamide.\u003c/p\u003e\n \u003cp\u003eYield: 5.1 g (yellow powder, 84.5.%).\u003c/p\u003e\n \u003cp\u003eMP: 276-279 deg C (decomp.); purity: 99.98% (High performance liquid chromatography (HPLC))\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Section3\" id=\"Sec12\"\u003e\n \u003ch2\u003e3.1.4. N-(1-Pyrenoylmethyl)-N,N,N-triethylammonium bromide [\u003cspan class=\"CitationRef\"\u003e28\u003c/span\u003e]\u003c/h2\u003e\n \u003cp\u003eTo acetonitile (50 ml, reagent grade) were added 1-(bromoacetyl)pyrene (2.0 g, 0.006 m) and triethylamine (redistilled, 1.5 ml, 0.011 m) and heated to reflux for 6 hours in an oil bath and the reaction monitored by TLC. The yellow solid formed was filtered and washed with hot benzene to afford the crude yellow powder (2 g) which was recrystallised from redistilled acetonitrile.\u003c/p\u003e\n \u003cp\u003eYield: 1.6 g (orange powder, 62.8%).\u003c/p\u003e\n \u003cp\u003eMP: 217-219 deg C (decomp.); purity: 97.74% (HPLC)\u003c/p\u003e\n \u003cp\u003eThe synthesized pyrene derivatives N-(1-Pyrenoylmethyl)pyridinium bromide (PM-PB) and N-(Pyrenoylmethyl)triethyl ammonium bromide (PM-TAB) are shown in Fig. 1.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec13\"\u003e\n \u003ch2\u003e3.2. Photophysical studies of PM-PB and PM-TAB in homogeneous media\u003c/h2\u003e\n \u003cdiv class=\"Section3\" id=\"Sec14\"\u003e\n \u003ch2\u003e3.2.1. Absorption Studies:\u003c/h2\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003eA and B represents the UV-Vis absorption spectra of PM-PB and PM-TAB in solvents of varying polarity, respectively. The absorption spectra of both the molecules extended well into the visible region. The absorption spectra of N-(1-Pyrenoylmethyl) pyridinium bromide (PM-PB) do not change much with solvents of different polarity. This indicates within the short time scale (10\u003csup\u003e\u0026minus;15\u003c/sup\u003e s) of the absorption phenomenon, PM-PB is insensitive to the solvent microenvironment around it. In the same set of solvents, the absorption spectrum of PM-TAB was also recorded. It has been observed that on changing solvent polarity PM-TAB shows almost similar absorption features as that of PM-PB. In both the case there is not much change in the energy of transition in different solvents, which implies that stabilization of the ground state species of the compounds by the solvents is not significant.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Section3\" id=\"Sec15\"\u003e\n \u003ch2\u003e3.2.2. Steady State Fluorescence Studies:\u003c/h2\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003eA and B shows the normalized steady state fluorescence spectra of PM-PB and PM-TAB in various solvents of different polarity, respectively. Fig. S1 in the supporting information shows the emission spectra of PM-PB and PM-TAB without normalization indifferent solvents. With increase in solvent polarity from heptane to water, there is a negligible red shift of ~10 nm in the spectral profile of PM-PB. In non-interacting solvents (like heptane and cyclohexane) the emission spectra of PM-PB and PM-TAB are more structured as compared to that in other solvents of moderate and high polarity. However, PM-TAB shows a remarkable red shift of ~50 nm in its emission spectral profile with increase in solvent polarity. Both the molecules are not completely soluble in water and showed a very weak fluorescence (Fig. S1 in the supporting information).\u003c/p\u003e\n \u003cp\u003eThe Stokes shift of PM-PB and PM-TAB fits well with ET(30) scales of solvent polarity (Fig. \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e) [\u003cspan class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e29\u003c/span\u003e]. ET (30) scale is the popularly used solvatochromic scale in the literature. It represents the transition energy in kcal mol\u003csup\u003e\u0026minus;1\u003c/sup\u003efor the longest wavelength absorption band of the dissolved pyridinium-N-phenoxide betaine dye. Correlation of solvent-dependent properties with the ET(30) scale often follows two distinct lines, one for the aprotic and another for the protic solvents. In the present case, ET (30) plot for PM-PB and PM-TAB shows two different slopes corresponding to aprotic and protic solvents.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv class=\"Section2\" id=\"Sec16\"\u003e\n \u003ch2\u003e3.3. Interaction of PM-PB and PM-TAB with bile salt (NaDC)\u003c/h2\u003e\n \u003cdiv class=\"Section3\" id=\"Sec17\"\u003e\n \u003ch2\u003e3.3.1. Steady State Fluorescence Intensity and Anisotropy Studies:\u003c/h2\u003e\n \u003cp\u003eThe variation of fluorescence intensity of PM-PB and PM-TAB with concentration of NaDC is shown in Fig. S2 in the supporting information. The corresponding plot of fluorescence intensity of PM-PB and PM-TAB with NaDC concentration has been given in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eA and B, respectively. With the concentration of NaDC, fluorescence intensity of both the molecules shows a sigmoid variation. The CMC point has been represented by the point of intersection of the horizontal line and the line of inflation (shown as dashed lines in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003eA and B). It is found to be 5 mM for NaDC. This is in agreement with the reported values range from 2\u0026ndash;10mM for NaDC [\u003cspan class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e21\u003c/span\u003e]. With increase in NaDC concentration, a remarkable increase in the fluorescence intensity of PM-PB and PM-TAB suggests that hydrophobic bile salt micellar aggregates provides a solubilizing environment to the molecules.\u003c/p\u003e\n \u003cp\u003eIn an organized media, the fluorescence anisotropy of a fluorescent molecule indicates the resistance offered by the microenvironment to its rotational movement. Hence, the change in the polarization of PM-PB and PM-TAB fluorescence acts as an index for the change in microviscosity of the immediate environment [\u003cspan class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e]. Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003eA and B represents the plots for the variation of steady state fluorescence anisotropy of PM-PB and PM-TAB as a function of NaDC concentration. Increase in fluorescence anisotropy with increasing NaDC concentration indicates restricted rotational mobility of PM-PB and PM-TAB in the progressive bile salt micellar environment.\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"Section3\" id=\"Sec18\"\u003e\n \u003ch2\u003e3.3.2. Fluorescence Lifetime Studies:\u003c/h2\u003e\n \u003cp\u003eTime resolved fluorescence decay studies have been performed to have a better understanding of the sensitivity of PM-PB and PM-TAB towards micellar aggregation of NaDC. Both the molecules show bi-exponential decay profile in presence and absence of NaDC (Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e). The lifetime values of PM-PB and PM-TAB with increasing NaDC concentration has been given in Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e. Unlike pyrene, there molecules show short lifetime values. \u0026nbsp;\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eTable 1.\u003c/strong\u003e Fluorescence lifetime values of(A) PM-PB and (B) PM-TAB with increasing NaDC concentration from 0to 18 mM. (\u0026lambda;\u003csub\u003eex\u0026nbsp;\u003c/sub\u003e= 370 nm, \u0026lambda;\u003csub\u003eem\u003c/sub\u003e= 450 nm)\u003c/p\u003e\n \u003cp\u003e(A)\u003c/p\u003e\n \u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.98581560283688%\"\u003e\n \u003cp\u003e[NaDC] \u0026nbsp; \u0026nbsp; \u0026nbsp;(mM)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003et\u003csub\u003es\u0026nbsp;\u003c/sub\u003e(ns), (a\u003csub\u003e1\u003c/sub\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003et\u003csub\u003el\u003c/sub\u003e (ns), (a\u003csub\u003e2\u003c/sub\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.73049645390071%\"\u003e\n \u003cp\u003et\u003csub\u003eavg\u003c/sub\u003e (ns)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.02127659574468%\"\u003e\n \u003cp\u003ec\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.98581560283688%\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e0.14 (25)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e5.29 (75)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.73049645390071%\"\u003e\n \u003cp\u003e5.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.02127659574468%\"\u003e\n \u003cp\u003e1.18\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.98581560283688%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e0.17 (23)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e5.41 (77)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.73049645390071%\"\u003e\n \u003cp\u003e5.36\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.02127659574468%\"\u003e\n \u003cp\u003e1.10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.98581560283688%\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e0.81 (28)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e5.13 (72)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.73049645390071%\"\u003e\n \u003cp\u003e4.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.02127659574468%\"\u003e\n \u003cp\u003e1.43\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.98581560283688%\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e1.02 (54)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e5.20 (46)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.73049645390071%\"\u003e\n \u003cp\u003e4.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.02127659574468%\"\u003e\n \u003cp\u003e1.41\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.98581560283688%\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e1.50 (87)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e4.84 (13)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.73049645390071%\"\u003e\n \u003cp\u003e2.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.02127659574468%\"\u003e\n \u003cp\u003e1.36\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.98581560283688%\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e1.56 (90)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e4.88 (10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.73049645390071%\"\u003e\n \u003cp\u003e2.42\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.02127659574468%\"\u003e\n \u003cp\u003e1.22\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.98581560283688%\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e1.60 (90)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e4.78 (10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.73049645390071%\"\u003e\n \u003cp\u003e2.39\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.02127659574468%\"\u003e\n \u003cp\u003e1.24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.98581560283688%\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e1.62 (91)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e5.07 (09)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.73049645390071%\"\u003e\n \u003cp\u003e2.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.02127659574468%\"\u003e\n \u003cp\u003e1.24\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.98581560283688%\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e1.64 (90)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e4.73 (10)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.73049645390071%\"\u003e\n \u003cp\u003e2.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.02127659574468%\"\u003e\n \u003cp\u003e1.32\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.98581560283688%\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e1.62 (88)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e4.30 (12)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.73049645390071%\"\u003e\n \u003cp\u003e2.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.02127659574468%\"\u003e\n \u003cp\u003e1.38\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.98581560283688%\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e1.61 (87)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.631205673758867%\"\u003e\n \u003cp\u003e4.14 (13)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.73049645390071%\"\u003e\n \u003cp\u003e2.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.02127659574468%\"\u003e\n \u003cp\u003e1.34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n \u003c/div\u003e\n \u003cp\u003e(B)\u003c/p\u003e\n \u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e[NaDC] \u0026nbsp; \u0026nbsp; \u0026nbsp;(mM)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003et\u003csub\u003es\u0026nbsp;\u003c/sub\u003e(ns), (a\u003csub\u003e1\u003c/sub\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003et\u003csub\u003el\u003c/sub\u003e (ns), (a\u003csub\u003e2\u003c/sub\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.54385964912281%\"\u003e\n \u003cp\u003et\u003csub\u003eavg\u003c/sub\u003e (ns)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.19298245614035%\"\u003e\n \u003cp\u003ec\u003csup\u003e2\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e0.68 (57)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e4.12 (43)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.54385964912281%\"\u003e\n \u003cp\u003e3.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.19298245614035%\"\u003e\n \u003cp\u003e1.15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e0.69 (59)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e4.04 (41)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.54385964912281%\"\u003e\n \u003cp\u003e3.38\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.19298245614035%\"\u003e\n \u003cp\u003e1.23\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e0.69 (57)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e3.86 (43)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.54385964912281%\"\u003e\n \u003cp\u003e3.25\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.19298245614035%\"\u003e\n \u003cp\u003e1.12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e0.70 (62)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e3.91\u003c/p\u003e\n \u003cp\u003e(38)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.54385964912281%\"\u003e\n \u003cp\u003e3.18\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.19298245614035%\"\u003e\n \u003cp\u003e1.41\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e0.71 (78)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e3.01 (22)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.54385964912281%\"\u003e\n \u003cp\u003e1.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.19298245614035%\"\u003e\n \u003cp\u003e1.15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e0.74 (76)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e2.93 (24)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.54385964912281%\"\u003e\n \u003cp\u003e1.96\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.19298245614035%\"\u003e\n \u003cp\u003e1.14\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e0.78 (83)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e2.95\u003c/p\u003e\n \u003cp\u003e(17)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.54385964912281%\"\u003e\n \u003cp\u003e1.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.19298245614035%\"\u003e\n \u003cp\u003e0.97\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e0.84 (81)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e2.86\u003c/p\u003e\n \u003cp\u003e(19)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.54385964912281%\"\u003e\n \u003cp\u003e1.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.19298245614035%\"\u003e\n \u003cp\u003e0.95\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e0.95 (79)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e2.74 (21)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.54385964912281%\"\u003e\n \u003cp\u003e1.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.19298245614035%\"\u003e\n \u003cp\u003e0.97\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e1.00 (81)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e2.77\u003c/p\u003e\n \u003cp\u003e(19)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.54385964912281%\"\u003e\n \u003cp\u003e1.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.19298245614035%\"\u003e\n \u003cp\u003e0.97\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e1.17 (84)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"21.75438596491228%\"\u003e\n \u003cp\u003e2.53\u003c/p\u003e\n \u003cp\u003e(16)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.54385964912281%\"\u003e\n \u003cp\u003e1.57\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.19298245614035%\"\u003e\n \u003cp\u003e0.97\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eIn water medium, due to poor solubility of PM-PB and PM-TAB there may be presence of small aggregates of the molecules along with the monomeric forms. This may be responsible for the biexponential decay of PM-PB and PM-TAB in water with a shorter and longer lifetime component. The monomeric form is expected to have a shorter lifetime value while the aggregated form to have longer lifetime. The amplitudes (a\u003csub id=\"isPasted\"\u003e1\u003c/sub\u003e,\u0026nbsp;a\u003csub\u003e2\u003c/sub\u003e) of the corresponding components, indicates the population of the respective components in their microenvironment. Amid a progressive formation of bile salt micellar aggregates on increasing NaDC concentration, there is an increase in amplitude and lifetime of the monomeric form. This may be due to the breaking of aggregated forms of PM-PB and PM-TAB in presence of bile salt and corresponding incorporation of the monomeric forms in to the NaDC micellar aggregates. In other words, there is an increase in solubility of PM-PB and PM-TAB with NaDC concentration. As compared to PM-TAB the variation is more prominent in case of PM-PB. \u0026nbsp;\u003c/p\u003e"},{"header":"Conclusions","content":"\u003cp\u003eThe synthesis and characterization of pyrene derivatives, N-(1-Pyrenoylmethyl)pyridinium bromide (PM-PB) and N-(1-Pyrenoylmethyl)-N,N,N-triethylammonium (PM-TAB) were discussed. With increase in solvent polarity from heptane to water, there is a negligible red shift of ~10 nm in the spectral profile of PM-PB. However, PM-TAB shows a reasonable red shift of ~50 nm in its emission spectral profile. The Stokes shift of PM-PB and PM-TAB fits well with ET (30) scale of solvent polarity. The steady state fluorescence intensity and dynamic fluorescence lifetime of these derivatives were found to be sensitive to the NaDC micellar aggregates. Present study provides a basic photophysical understanding of PM-PB and PM-TAB in the absence and presence of physiologically important bile salts.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eACKNOWLEDGMENTS:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors thank Prof. K. K. Balasubramanian and Prof A. K. Mishra\u003csup\u003e \u003c/sup\u003eof IIT Madras, India, for their valuable discussion and help in collecting fluorescence lifetime data. \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAUTHOR DECLARATIONS:\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding \u003c/strong\u003eThere are currently no funding sources. \u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflicts of interest \u003c/strong\u003eThere are no conflicts to declare.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical Approval\u003c/strong\u003e All authors declare Ethics approval.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Participate\u003c/strong\u003e All authors Consent to participate.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for Publication\u003c/strong\u003e All authors Consent for publication.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability \u003c/strong\u003eAll the data that have been referred to in the manuscript without being included have been given in the Supporting Information. Figures showing emission spectra of PM-PB and PM-TAB in solvents of different polarity (Fig. S1), emission spectra of PM-PB and PM-TAB with increasing NaDC concentration from 0 to 18 mM (Fig. S2) are available in the supporting information.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCode Availability \u003c/strong\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e Synthesis, chemical characterization has been done by MS, SD, and supervised by SKR, and KV. Photophysical studies has been done by MS, MM, and supervised by MM. All authors read and approved the final manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eNiko Y, Hiroshige Y, Kawauchi S, Konishi G (2012) Tetrahedron, 68, 6177\u0026ndash;6185 and reference their in\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSubuddhi U, Haldar S, Sankararaman S, Mishra AK (2006) Photochemical and Photobiological Sciences 5:459\u0026ndash;466\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSubuddhi U, Haldar S, Sankararaman S, Mishra AK (2008) J Photochem Photobiol A 200:381\u0026ndash;387\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSarkar I, Hemamalini A, Das TM, Mishra AK (2016) RSC Adv 6:27933\u0026ndash;27943\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMilosavljevic BH, Thomas JK (1988) J Phys Chem 92:2997\u0026ndash;3001\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSu FK, Liau GF, Hong JL (2007) J Polym Sci Part B Polym Phys 45:920\u0026ndash;929\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMiller E, Styczynska DJ (2009) Spectrochimica Acta Part A 72:312\u0026ndash;321\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eColeman R (1987) Bile salts and biliary lipids. 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Chem, 19873, 48,3577\u0026ndash;3580\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAvijit Jana S, Atta SK, Sarkar ND, Pradeep Singh (2010) Tetrahedron 66:9798\u0026ndash;9807\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAnuradha M (2007) Swati. Colloid Polym Sci 285:397\u0026ndash;404\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eJacques J, Marquet A (1973) Org Synthesis 53:111\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNynke M, van Spijker AM, Cornelisse J (1990) J. Org. Chem., 55, 756-758\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGridin VV, Kim TK, Bekkerman A, Bulatov V, Jung K-H, chechtera I (2003) Eur J Mass Spectrosc 9:187\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSongjie Yu S, Liu Yu, Lan B Van (2015) J Am Chem Soc 137:1623\u0026ndash;1631XingweiLi\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMarcus Y (1991) J Solut Chem 20:929\u0026ndash;944\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-fluorescence","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jofl","sideBox":"Learn more about [Journal of Fluorescence](https://www.springer.com/journal/10895)","snPcode":"10895","submissionUrl":"https://submission.nature.com/new-submission/10895/3","title":"Journal of Fluorescence","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Pyrenoyl salts, Bile salt, Micellization, Sodium deoxycholate, Fluorescence ","lastPublishedDoi":"10.21203/rs.3.rs-1308526/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-1308526/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe present work describes the synthesis and characterization of pyrene derivatives, N-(1-Pyrenoylmethyl)pyridinium bromide (PM-PB) and N-(1-Pyrenoylmethyl)-N,N,N-triethylammonium bromide (PM-TAB). Photophysical behavior of these molecules has been studied in various protic and aprotic solvents. Using steady state fluorescence intensity, fluorescence anisotropy and dynamic fluorescence lifetime studies, the sensitivity of these molecules towards the micellization process of bile salts has been monitored. These derivatives have been effectively used in estimating critical micellar concentration (CMC) of bile salt, sodium deoxycholate (NaDC).\u003c/p\u003e","manuscriptTitle":"Photophysical Behaviour of Novel Quaternary Pyrenoyl Salts and Their Sensitivity Towards Bile Salt Micellization","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-02-07 17:27:31","doi":"10.21203/rs.3.rs-1308526/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2022-02-07T04:21:23+00:00","index":0,"fulltext":""},{"type":"reviewersInvited","content":"","date":"2022-02-04T16:55:27+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2022-02-03T04:19:55+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Fluorescence","date":"2022-01-29T01:33:33+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-fluorescence","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jofl","sideBox":"Learn more about [Journal of Fluorescence](https://www.springer.com/journal/10895)","snPcode":"10895","submissionUrl":"https://submission.nature.com/new-submission/10895/3","title":"Journal of Fluorescence","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"a64d459b-07ce-410a-b4fa-deabab6fdbed","owner":[],"postedDate":"February 7th, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2022-04-11T12:09:03+00:00","versionOfRecord":[],"versionCreatedAt":"2022-02-07 17:27:31","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-1308526","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-1308526","identity":"rs-1308526","version":["v1"]},"buildId":"FbvkV6FR0MCFSLy54lSbu","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}