posted on 2023-11-24, 00:34authored byFatemeh Beyranvand, Armaghan Khosravi, Fatemeh Zabihi, Mohammad Nemati, Mohammad Fardin Gholami, Mahdi Tavakol, Siamak Beyranvand, Shabnam Satari, Jürgen P. Rabe, Abdollah Salimi, Chong Cheng, Mohsen Adeli
Manipulation
of the structure of covalent organic frameworks at
the molecular level is an efficient strategy to shift their biological,
physicochemical, optical, and electrical properties in the desired
windows. In this work, we report on a new method to construct chiral
triazine frameworks using metal-driven polymerization for enantiodiscrimination.
The nucleophilic substitution reaction between melamine and cyanuric
chloride was performed in the presence of PdCl2, ZnCl2, and CuCl2 as chirality-directing agents. Palladium,
with the ability of planar complex formation, was able to assemble
monomers in two-dimensions and drive the reaction in two directions,
leading to a two-dimensional triazine network with several micrometers
lateral size. Nonplanar arrangements of monomers in the presence of
ZnCl2 and CuCl2, however, resulted in calix
and bouquet structures, respectively. While 2D and bouquet structures
showed strong negative and positive bands in the CD spectra, respectively,
their calix counterparts displayed long-range weak negative bands.
In spite of the ability of both calix and bouquet networks to load l-histidine 35 and 50% more than d-histidine from pure
enantiomers, respectively, only calix counterparts were able to take
up this enantiomer (78%) from the racemic mixture. The two-dimensional
polytriazine network did not show any specific interactions with pure
enantiomers or their racemic mixtures.