On the mechanism of intramolecular charge transfer in para-disubstituted diphenylacetylenes containing electron-donating and electron-accepting groups: role of πσ∗ state in electron-transfer dynamics

Evidence is presented for direct involvement of πσCC∗ state in the intramolecular charge transfer of p-disubstituted diphenylacetylene containing an electron-donating group at one end and an electron-withdrawing group at the other. Comparison of the computed potential energy curves and the experimental transient absorption spectra with the corresponding data for N,N-dimethylaminobenzonitrile (DMABN) suggests that the πσCN∗ state may also play a central role in the photoinduced electron-transfer of DMABN and related molecules.