Intermolecular Interaction in Multicomponent Supramolecular Complexes through Hydrogen-Bonding Association

Abstract

A series of main-chain hydrogen-bonded supramolecular complexes have been prepared by self-assembly of proton donor (diacid) and acceptor (bipyridyl ethylene) through the formation of intermolecular hydrogen bonds. The phase transition behaviors were studied using differential scanning calorimetry and polarized optical microscopy. X-ray photoelectron spectroscopy study indicated that the binding energy of N 1s upshifted ca. 0.8 eV, which was within the limit of the hydrogen-bonding interaction. Solid-state CP/MAS 13C NMR spectroscopy experiments revealed that an induced upfield shift (Δδ ≥ 4 ppm) of carbonyl carbon in solid state was observed as a result of the formation of intermolecular hydrogen bond. The natural abundance CP/MAS 15N NMR spectroscopy also supported that the molecular complexes with hydrogen bond characteristics rather than zwitterionic complexes were formed on the basis of the change in 15N chemical shift.