Conformation-dependent adsorption of natural Riparins on BNNT: Insights from a first-principles study

A first-principles investigation of the adsorption of Riparin I, II and III molecules on a zigzag boron nitride nanotube BNNT (5,0), together with a quantum-chemical characterization of the isolated molecules, was performed. The isolated Riparins exhibit increasing dipole moment (2.15−3.83 D), polarizability (199.63−210.76 a.u.), and electrophilicity (1.53−1.72 eV) from Riparin I to III, indicating enhanced reactivity. Stable BNNT–Riparin complexes are formed, with adsorption energies ranging from -0.661 to -0.777 eV and equilibrium adsorption distances of 2.34−2.68 Å, corroborated by charge analysis. Adsorption significantly modifies the electronic structure, producing charge redistribution, orbital hybridization, and band-gap reductions of up to 37% while preserving the structural stability of the nanotube. Riparin III exhibits the strongest interaction, consistent with the trends predicted from the isolated molecule properties. These findings highlight BNNT–Riparin systems as promising candidates for nanoscale sensing, drug delivery, and bio-nanoelectronic applications.