Local chirality measures in QSPR : IR and VCD spectroscopy

Abstract

The paper presents the first successful attempt at obtaining Quantitative Structure–Property Relationships (QSPR) of vibrational spectra parameters with chirality measures. The local chirality measures defined based on the Sinister–Rectus Chirality and Continuous Chirality approaches were calculated and intercompared for selected fragments of 28 5-substituted 1-cyano-1H-indenes. It appeared that there is no correlation between global and local variants of the chirality measures which additionally are less linearly interdependent than the global ones. The obtained local chirality measures were correlated with the frequency, IR and VCD intensity of the ν(CN) and ν(C*H) stretching modes. It was proven that vibrational spectroscopy gives some information on the local chirality of molecules. Especially, some well-isolated VCD bands could be a proper experimental, physical measure of local chirality. It was also demonstrated that some local chirality measures are highly collinear with the substituent effect descriptors σ_p and pEDA(I), showing that the electronic properties of a substituent may significantly influence the chirality of an aromatic system.