Concentration dependent dual fluorescence of 4-(N,N-dimethylamino)benzoic acid in chloroform

Abstract

The intramolecular charge transfer (ICT) dual fluorescence of 4-(N,N-dimethylamino)benzoic acid (DMABOA) in chloroform was found concentration dependent and the fluorescence quantum yield ratio of the ICT to the locally excited (LE) state band, Phi'/Phi, increases with DMABOA concentration. Whereas the shape of absorption spectrum remains unchanged, the IR data establish the formation of ground state intermolecular hydrogen bonding between DMABOA molecules. The excitation spectra of DMABOA corresponding to the ICT and the LE emission were found identical at each DMABOA concentration but changing with increasing DMABOA concentration. These observations point to the possibility that the H-bonding mediated excited-state proton transfer facilitates the intramolecular charge transfer process. (C) 1999 Elsevier Science B.V. All rights reserved.