Hydrogen bonding and TICT molecules in ground state

Abstract

A comparative absorption study between the flexible molecule and its blocked homologue confirms that the twist around the C-N bond, in the ground state of "anilines" in solution is the common origin of the anomalous temperature effects: • the collapse of the second electronic band for N,N-dialkylanilines; • the anomalous red shift (ARS) of the first band for p-substituted N,N-dialkylanilines. This twist is due to the complexation by hydrogen bonding between "anilines" and traces of water present as impurity in the aprotic solvents. Similar twisted complexes- and hence similar anomalies-are obtained, at room temperature, in rigid hydrogen-bonded matrices, such as polyvinyl-alcohol (PVA), in both cases (N,N-dialkylanilines and p-substituted N,N-dialkylanilines). © 1992 Indian Academy of Sciences.