Excited state proton transfer in 2-hydroxypyridine-ammonia clusters: Theoretical investigation

The electronic and structural properties of 2-hydroxypyridine (2HP) and 2HP · (NH3)n (n = 1-4) and their tautomers in the excited state are studied. It was found that at least three ammonias are needed to produce a stable excited ion-pair cluster for the enol form. This study shows that the excited state proton transfer in these clusters is endoergic and the endoergicity diminishes for greater size. These behaviors are also found in the ground state in our previous study, where DFT calculations are performed.