Thermoresponsive reversible host-guest supramolecular nanotubular self-assembly of octyl-2-acetoxybenzoate@b-CD

The present work deals with supramolecular host-guest complexation of octyl-2-acetoxybenzoate (OCASP) into b-cyclodextrin (b-CD) which spontaneously self-assembled into a thermoresponsive nan-otubular architecture at a molar ratio of 1:1. OCASP was synthesized as a prodrug of aspirin (ASP) in an aim to reduce its inherent toxicity. The OCASP@b-CD inclusion complex (IC) was characterized by UV-Vis, FT-IR, WAXRD, 13C CP/MAS NMR spectroscopy and SEM. TEM and AFM revealed the formation of nanotube with a diameter of-50 nm. Reversible switching of assembly and disassembly is triggered by decreasing and increasing of temperature, as is evidenced by the turbidity measurement of a 5% solu-tion of OCASP@b-CD system. Hydrophobic interactions among the successive OCASP@b-CDs are the chief driving force behind the formation of hierarchy as is evidenced by the control experiment with urea dur-ing its preparation. The stepwise formation of such a hierarchy was further characterised by molecular dynamics (MD) studies in 15 ns time scale using 2 fs time step. The developed stimuli responsive system would permit tailoring of its physical properties and it is anticipated that it will bring light on the fabri-cation of novel smart materials.(c) 2022 Elsevier B.V. All rights reserved.