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) (I) (4ABN-(H2O)(I)) hydrogen-bonded complex have been measured by the reson ance-enhanced multiphoton ionization (REMPI) and infrared-dip (IR-dip) spec troscopy. Both the amino and cyano groups form intermolecular hydrogen bond with water, providing two stable isomers. It has been found that the subst itution of the CN group at the para-position of aniline changes the electro nic nature of the amino group in the So state from a proton acceptor to a p roton donor. (C) 2001 Elsevier Science B,V, All rights reserved.