On the impact of a phosphoryl group in the recognition capabilities of 2-aminopyridines toward carboxylic acids

Abstract

Inspired by natural molecular recognition processes, many research efforts have been routed in recent years towards the design of new host-guest molecular systems based on non-covalent interactions. Within this field, 2-aminopyridines (2APs) have been widely studied due to their tunable spectroscopic response in presence of carboxylic acids. Herein, we present and analyze a novel family of 2AP core compounds based on 2phosphorylamidopyridine (2PAP). Linear response timedependent density functional theory (TD-DFT) has been used to characterize and model several spectroscopic properties of 2PAP. Our results, validated through experiments, show that TD-DFT can provide a reliable description of the electronic excited states of these aromatic systems. In addition, we have also studied the amino-imino tautomerization of 2AP and 2PAP under the light of TD-DFT tools. We show that the presence of a carboxylic acid has a catalytic effect on the tautomerization reaction, which otherwise does not occur spontaneously at room temperature. These results suggest that this low-cost computational approach can be applied to more complex organic systems derived from 2-aminopyridine, paving the way for the development of potentially useful sensing materials and organic species for molecular recognition.