Electronic and infrared spectra of jet-cooled 4-aminobenzonitrile-H2O. Change of NH2 from proton acceptor to proton donor by CN substitution

The electronic and infrared spectra of jet-cooled 4-aminobenzonitrile–(H2O)1 (4ABN–(H2O)1) hydrogen-bonded complex have been measured by the resonance-enhanced multiphoton ionization (REMPI) and infrared-dip (IR-dip) spectroscopy. Both the amino and cyano groups form intermolecular hydrogen bond with water, providing two stable isomers. It has been found that the substitution of the CN group at the para-position of aniline changes the electronic nature of the amino group in the S0 state from a proton acceptor to a proton donor.