Influence of Pyrrolidinium-Based Ionic Liquid on the Interfacial Activity and Droplet Leaf Surface Wettability of Nitenpyram: Experimental and Theoretical Approach

Abstract

Effective pesticide utilization is an essential matter that needs attention, owing to the vast usage of pesticides worldwide. Herein, a pyrrolidinium-based ionic liquid (IL) 1-hexyl-1-methylpyrrolidinium bromide [PyrC₆]Br^– was chosen to solve the purpose of an adjuvant to enhance the surface activity and wettability of a pesticide nitenpyram (NTP). The critical micellar concentration of IL-NTP was evaluated using surface tension and spectrophotometric techniques, viz., UV–visible and steady state fluorescence. ΔG_ads⁰ and ΔG_mic⁰ were also calculated, and it was found that the adsorption process was favored over micellization. The sizes and stability of IL-NTP aggregates were analyzed using DLS and zeta potential measurements, respectively, which indicated optimum stability for IL-NTP when IL was present at its cmc value. The wettability of IL-NTP was found to be enhanced as compared to NTP in aqueous solution by evaluating it on various crop leaves using static contact angle measurements. Further, DFT calculations were performed which revealed complex formation between IL and NTP and various thermal and physiochemical parameters were obtained and it was found that IL and NTP bind through electrostatic interactions. Our results suggest an improved effect of IL on NTP, which could help in developing an IL-NTP composition that might result in better activity on crops.