Solvent Isomerism and Metal Ion-mediated Chiral Resolution via Chiral Amplification forming superhelices polymer

The chiral resolution and separation of enantiomers is of great significance in both life science and pharmaceutical industry. Herein, we empoly butanol solvent isomerism and metal ion-coordintion to target chiral spontaneous resolution through chiral amplification forming superhelix. In Ni/ Rac -BrpempH 2 system, cyan flake crystal compounds Meso -1C and light blue gel 2S were generated from the reaction of NiSO 4 ·6H 2 O and racemic 4-Br-(1-phenylethylamino)methylpho sphonate (4-BrpempH 2 ) under hydrothermal conditions at 100 °C for 2 days, in 20 % ethyl alcohol (EA)/H 2 O and 40 % sec-butyl alcohol (SBA)/H 2 O, respectively. Noteworthly, compound 2S is an aggregate of left-handed and right-handed nanohelices ( P & M ) with the diameter about 60 nm and the pitch of 50 nm, which indicated chiral self-resolution was occured. Further to obtain a homochiral macroscopic helix, D/L-phephenylalanine (D-/L-Phe) or D-/L-Pipecolinic acid (D-/L-Pca) are added to the reaction system. Interestingly, the right-hand superhelices ( 2S- M ) were obtained at the present of L-Phe additive, the left-hand superhelices ( 2S- P ) at the present of D-Phe additive. However, when chiral Pca is used as a chiral additive, the opposite result to the above occurs, i.e., the addition of D-Pca results in a left-handed helix ( 2S- P ) and vice versa for a right-handed helix ( 2S- P ). In this case, the cosolvent SBA and chiral additive play critical roles in chiral resolution. Furthermore, helical products 2S -P and 2S -M obtained from D-/L-Phe chiral resolving agents exhibited comparable recognition capacities for Trp enantiomers.This study offers a novel method for chiral resolution through chiral amplification and provides a new pathway for the design and self-assembly of chiral materials with controllable handedness, especially in coordination polymer systems.