Precision Nanocluster-Based Toroidal and Supertoroidal Frameworks Using Photocycloaddition-Assisted Dynamic Covalent Chemistry.

Lakshmi, K. V. and Jose, V. Rival and Pakath, Sreeraj and Sindhu, R. Nambiar and Jeyabharathi, C. (2023) Precision Nanocluster-Based Toroidal and Supertoroidal Frameworks Using Photocycloaddition-Assisted Dynamic Covalent Chemistry. Small, 19. p. 2207119.

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Abstract

Atomically precise nanoclusters (NCs) have recently emerged as ideal building blocks for constructing self-assembled multifunctional superstructures. The existing structures are based on various non-covalent interactions of the ligands on the NC surface, resulting in inter-NC interactions. Despite recent demon�strations on light-induced reversible self-assembly, long-range reversible self�assembly based on dynamic covalent chemistry on the NC surface has yet to be investigated. Here, it is shown that Au25 NCs containing thiolated umbelliferone (7-hydroxycoumarin) ligands allow [2+2] photocycloaddition reaction-induced self-assembly into colloidal-level toroids. The toroids upon further irradiation undergo inter-toroidal reaction resulting in macroscopic supertoroidal honey�comb frameworks. Systematic investigation using electron microscopy, atomic force microscopy (AFM), and electron tomography (ET) suggest that the NCs initially form spherical aggregates. The spherical structures further undergo fusion resulting in toroid formation. Finally, the toroids fuse into macroscopic honeycomb frameworks. As a proof-of-concept, a cross-photocycloaddition reaction between coumarin-tethered NCs and an anticancer drug (5-fluoro�uracil) is demonstrated as a model photo-controlled drug release system. The model system allows systematic loading and unloading of the drug during the assembly and disassembly under two different wavelengths. The results suggest that the dynamic covalent chemistry on the NC surface offers a facile route for hierarchical multifunctional frameworks and photocontrolled drug release.

Item Type:	Article
Uncontrolled Keywords:	Atomically precise nanoclusters, self-assembled multifunctional superstructures.
Subjects:	600 Technology > 02 Engineering & allied operations
Divisions:	Food Safety Analytical Quality Control Lab
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	25 May 2023 04:51
Last Modified:	25 May 2023 04:51
URI:	http://ir.cftri.res.in/id/eprint/16468

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