Supracube engineering of Cucurbit[8]uril stabilized silver cube building blocks for organized host-guest chemistry

Abstract

Organic supramolecule based hierarchical organization of colloidal noble metal nanoparticles (NMNP) is a complex method for developing new materials with supra-architectures. To date, there is a lacuna in providing controlled anisotropy in micron sized self-assembly of isotropic spherical nanoparticles with high chemical stability. In this work, we have assorted acidic solution of cucurbit[8]uril (CB[8]) along with silver nanoparticles (AgNP) of 8.04 ± 1.3 nm diameter to develop colloidal silver supracube (Agsc) with an edge length of 2.5 ± 1.2 μm. We have reconnoitered the Agsc formation pathway via CB[8] based self-assembly, which shows the generation of much smaller silver nanocubes as building blocks (Agnc). The colloidal solution of Agnc with an edge length of 400 ± 8.2 nm shows dual surface plasmon resonance (SPR) peaks due to introduction of anisotropy. Precise control over the dimension of the cubes with varying CB[8] concentration provides an opportunity to engineer the fusion of building blocks around the corner of cubes to produce Agsc. The dye inclusion efficacy of these colloidal supra-architectures in the internal void space as well as surface residing CB[8] cavity has been examined with the organized host-guest chemistry of coumarin-7 (C7)‒CB[8] complex. Adamantylamine triggered selective recovery of C7 from Agsc elucidates the distinctive host-guest behavior of Agnc and Agsc.