Collect. Czech. Chem. Commun. 1990, 55, 1891-1895

Influence of solvent polarity on the dual fluorescence of p-N,N-dimethylaminobenzonitrile: An AM1 theoretical study

Peter Ertl

Chemistry Institute, Comenius University, 842 15, Bratislava


Twisting of the NMe2 group in p-N,N-dimethylaminobenzonitrile (DMABN) was investigated using AM1 semiempirical method with configuration interaction. Effect of polar media was considered by placing + and - charge centers ("sparkles") at appropriate places opposite the molecule. Optimized ground state geometry of DMABN is slightly twisted with the lowest vertical excited state of 1B character. As the polarity of media increases and/or the - NMe2 group twists, the symmetric 1A excited state having considerable charge separation becomes energetically favorable. Anomalous long-wavelength emission of DMABN comes from this state.