Modulating the Roaming Dynamics for the NO Release in <i>ortho</i>-Nitrobenzenes
Namitha Brijit Bejoy, Prahlad Roy Chowdhury, G. Naresh Patwari
Abstract
The dynamics of NO release upon photodissociation of nitroaromatic compounds is dependent on the nature of the interaction between the NO 2 group and substituent in the ortho position. A bimodal (slow and fast) translational energy distribution of the NO photofragment indicates the presence of two distinct NO elimination channels. The slow-to-fast branching ratio for the NO release is regulated by the hydrogen bonding ability of the ortho substituent and follows the order [OH > NH 2 > CH 3 > OCH 3 ], indicating that the intramolecular hydrogen bonding plays a pivotal role in NO release dynamics. Further, the topology of the triplet state potential energy surface acts as a doorway to the dissociation pathway switching between the roaming and nonroaming mechanisms, with hydrogen bonding substituents (OH and NH 2 ) favoring the roaming mechanism.