The impact of the central metal on the structural, linear, and nonlinear optical performance of BDC for possible use in energy storage applications

In a variety of industrial fields, including gas storage and separation, electrochemical energy storage, catalysis, and sensing, metal-organic frameworks (MOFs) have shown an elevated level of performance in recent years. In the current paper, benzene dicarboxylic (BDC) acid as a ligand was used to link with Cu(II) and Fe(III) ions via a casting method to generate two different metal-organic frameworks, namely Cu-BDC MOF and Fe-BDC MOF, respectively. The structural, linear, and nonlinear optical characterizations of the as-prepared two MOFs were investigated. The morphology of Cu-BDC MOF and Fe-BDC MOF was confirmed by using XRD, and SEM. Utilizing the TGA, the thermal stability properties of the as-prepared MOFs were evaluated, and referred that Cu-BDC MOF was more thermally stable than Fe-BDC MOF. The investigated optical transmission properties in the wavelength region 325–1100 nm confirmed that Fe-BDC was greater than Cu-BDC by 33 %. Wemple–DiDomenico and Tauc models were used to analyze the optical constants. The dispersion parameters of Cu-BDC MOF were identified as much greater than those of Fe-BDC MOF. This could be interpreted by the increase in Cu valence electrons, which occurs primarily due to the rise in the number of cations. The outcome of this work is suggested to help in understanding the effect of metal nodes on the structural and optical properties of MOFs.