From biomass to bioactivity: Butea monosperma bark-derived carbon quantum dots for benzopyran synthesis and their in silico studies

Abstract

Carbon quantum dots represent a new class of green nanomaterials with exceptional catalytic efficiency and excellent biocompatibility. In this study, a sustainable and green synthetic protocol has been developed using biomass-derived carbon quantum dots obtained from Butea monosperma bark as a green nanocatalyst. The catalyst was comprehensively analyzed using HRTEM, SAED, EDX, FT-IR, XRD, UV-visible, and fluorescence spectroscopy, confirming its amorphous nature, surface functionalization, and optical properties, with an average particle diameter of 5.78 nm. The catalyst was successfully utilized for the preparation of a diverse library of benzopyran derivatives via the reaction of substituted salicylaldehydes with various C–H activated compounds. The reactions were carried out under mild conditions using EtOH/H₂O (1 : 1) solvent system at room temperature. A diverse library of 17 benzopyran derivatives was synthesized in excellent yields (83–97%) within short reaction times (10–35 min). The catalyst showed remarkable tolerance toward both electron-withdrawing and electron-donating substituents, demonstrating its broad substrate scope and selectivity. The catalyst exhibited excellent recyclability for up to seven consecutive cycles with minimal loss of catalytic activity and favourable green chemistry metrics. Furthermore, in silico studies were conducted to evaluate the biological potential of the synthesized compounds against neuropeptide Y5 receptor antagonists, kinase inhibition, and testosterone 17β-dehydrogenase (NADP⁺). Among them, compounds 3j, 3i, and 3q showed the most promising binding affinities with docking scores of −18.91, −14.35, and −19.49 kcal mol⁻¹, respectively. Key features of the developed protocol include novel source of biomass utilization, metal-free catalysis, operational simplicity, ambient reaction conditions, recyclability and high sustainability.