Assembly of Polygonal Nanoparticle Clusters Directed by Reversible Noncovalent Bonding Interactions

Abstract

The reversible molecular template-directed self-assembly of gold nanoparticles (AuNPs), a process which relies solely on noncovalent bonding interactions, has been demonstrated by high-resolution transmission electron microscopy (HR-TEM). By employing a well-known host-guest binding motif, the AuNPs have been systemized into discrete dimers, trimers, and tetramers. These nanoparticulate twins, triplets, and quadruplets, which can be disassembled and reassembled either chemically or electrochemically, can be coalesced into larger, permanent polygonal structures by thermal treatment using a focused HR-TEM electron beam.

Selectivity among Two Lectins: Probing the Effect of Topology, Multivalency and Flexibility of “Clicked” Multivalent Glycoclusters

“…[60][61][62][63][64][65] The synthesis of the tetrapropargylated porphyrin 17 [66,67] was performed from 4-propargyloxy-benzaldehyde (16) [68] (Scheme 3). The subsequent CuAAC process systematically incorporated Cu I in the non-metallated porphyrin 17 during the cycloaddition reaction leading to poor yields of cycloadducts or even complex mixtures of decomposed molecules.…”

“…The introduction of Zn 2 + was, therefore, required prior to the "click" conjugation to obtain the desired Zn-metallated porphyrin 18. [66,67] [24] were used as the monovalent references to determine the influence of the linker attached at the anomeric position, but also to study the importance of both valency and topology for each scaffold (Scheme 4). We have also recently synthesized two other tetravalent glycoclusters [24] based on a calix [4] [a]…”

“…The organic layer was then extracted with chloroform (3 30 mL), washed with saturated NH 4 Cl (2 30 mL), dried (Na 2 SO 4 ), filtered and concentrated under reduce pressure. (17): [66,67] Propionic acid (100 mL) was added to a 500 mL round-bottomed flask flushed with argon. The mixture was heated at 120 8C upon vigorous stirring and a mixture of para-propargyl-benzaldehyde (16) [68] (3.6 g, 22.5 mmol, 1 equiv) and pyrrole (1.6 mL, 22.5 mL, 1 equiv in 5 mL of propionic acid) was added dropwise.…”

“…After evaporation and re-dissolution in a minimal quantity of chloroform, dropwise incorporation of methanol yielded the pure porphyrin 17 (1.09 g, 23 %) as a deep-purple shiny solid. (18): [66,67] Porphyrin (17) (500 mg, 0.60 mmol, 1 equiv) and ZnCl 2 (410 mg, 3 mmol, 5 equiv) were introduced into a Biotage Initiator 2-5 mL vial. The vial was flushed with argon and protected from light (aluminium sheet).…”

Colloidal Assembly: The Road from Particles to Colloidal Molecules and Crystals

“…A linker may simply connect two adjacent colloids, or with proper design, be able to bind multiple colloids and direct their final structures. [133] Recently, halogen bonding was explored for colloidal assembly. Halogen bonding refers to noncovalent interactions involving halogen aroms (except fluorine) as acceptors of electron density from Lewis bases.…”