A NMR hybrid J-coupling alternation (hJCA) parameter linearly correlated to properties of intermolecular H-bonded chains

Intermolecular H-bonds play a fundamental role for macromolecules in biochemistry. In this sense, the analysis of NMR scalar couplings across H-bonded chains has emerged as an important method to unveil the quasi-covalent character of the so-called intermolecular self-assembly. To investigate relationships between these couplings and molecular properties of H-bonded chains, we propose a hybrid J-coupling alternation ((h)JCA) parameter. Our definition involves intra and intermolecular hyperfine contributions useful for chains with different parities. The results for increasing (HCN)n (n = 4-13) chains give evidence of linear correlations between (h)JCA and other molecular properties. For example, (h)JCA exhibits a linear correlation with the energy gap for these chains, which may be attributable to a possible degree of hyperconjugation of hydrogen bonding in HCN chains.