Abstract

Chiral resolution is essential in the pharmaceutical and food industries, as well as in material engineering, due to the unique properties of enantiomers. This study explores the coordination polymerization of homochiral (L- and D-) and racemic (DL-) copper aspartate (CuAsp) and spatiotemporal resolution of racemic aspartic acid (DL-Asp) using L- and D-proline (Pro)-copper complexes as tailor-made additives (TMAs) via reaction-diffusion frameworks (RDFs) in both 1D and 2D agar gel systems. The imposed supersaturation gradient translates into a gradient of crystal sizes facilitating the formation of CuAsp coordination polymers with spherulitic morphology. Solid-state circular dichroism (CD) and powder X-ray diffraction (PXRD) analyses confirmed the chiral nature and crystalline phases of the CuAsp polymers, with DL-CuAsp forming as conglomerates. Drawing inspiration from Kaoru Harada’s seminal work on the resolution of DL-Asp using L- and D-Pro-copper complexes, the preferential crystallization with ‘rule of reversal’ was evident, where the crystalline CuAsp near the liquid-gel interface exhibited the opposite configuration to those of the TMA. Variability in chirality was noted further from the interface due to concentration gradients. These findings underscore the utility of RDF coupled with the rule of reversal in chiral resolutions, offering an effective strategy for enhancing enantioselectivity in racemic compounds across various applications.