Elucidation of specific aspects of dielectric constants of conjugated organic compounds: a QSPR approach.

The characteristic aspects of dielectric constants of π-conjugated compounds are elucidated by a quantitative structure property relationship (QSPR) study. To develop a QSPR model, among 141 collected π-conjugated compounds, a subset of 116 compounds was used as the training set for the model building and the rest was used as the test set for the model validation. Statistical regression models using 396 molecular descriptors were generated based on the genetic function approximation algorithm. The predicted dielectric constants obtained by the best model are highly correlated with the experimental values (squared correlation coefficient R(2) of 0.93 and 0.97 for the training and test sets, respectively), while a previous prediction model for general organic molecules (Sild S, Karelson M (2002) J Chem Inf Comput Sci 42:360-367) is not valid for our collected π-conjugated organic compounds. It has been known that the dielectric constants of organic materials are largely influenced by orientational correlations of the constituent molecules. In general, hydrogen bonding is one of the most important intermolecular interactions affecting orientational correlation. In the case of π-conjugated compounds, however, π-π interaction could be another comparable interaction with the hydrogen bonding.