Chalcogen Atom Size Dictates Stability of Benzene-1,3,5-triamide Polymers: Overlooked Role of Geometrical Fit for Enhanced Hydrogen Bonding.

ABSTRACT

Our quantum chemical analyses elucidated how the replacement of O in the amide bonds of benzene-1,3-5-tricarboxamides (OBTAs) with the larger chalcogens S and Se enhances the intermolecular interactions and thereby the stability of the obtained hydrogen-bonded supramolecular polymers due to two unexpected reasons i) the SBTA and SeBTA monomers have a better geometry for self-assembly and ii) induce stronger covalent (hydrogen-bond) interactions besides enhanced dispersion interactions. In addition, it is shown that the cooperativity in benzene-1,3,5-triamide (BTA) self-assembly is caused by charge separation in the σ-electronic system following the covalency in the hydrogen bonds.