Methionine controlled impediment of secondary nucleation leading to nonclassical growth within self-assembled de novo gold nanoparticles

The conventional key steps for seed mediated growth of noble metal nanostructures involve classical and nonclassical nucleation. Furthermore, the surface of the seed catalytically enhances the secondary nucleation involving Au+ to Au0reduction, thus providing in-plane growth of seed. In contrast to this well-established growth mechanism, herein we report the unique case of methionine (Met) controlled seed mediated growth reaction, which rather proceeds via impeding secondary nucleation in presence of citrate stabilized gold nanoparticle (AuNP). The interaction between the freshly generated Au+ and thioether group of Met in the medium restricts the secondary nucleation process of further seed catalyzed Au+ reduction to Au0. This incomplete conversion of Au+, as confirmed by X-ray photoelectron spectroscopy (XPS), results in a significant enhancement of the zeta (z) potential even at low Met concentration. Nucleation of in situgenerated small-sized particles (nAuNPs) takes place on the parent seed surface followed by their segregation from the seed. Self-assembly process of these nAuNPs arises from the aurophilic interaction among the Au+. Furthermore, the time dependent growth of smaller particles to larger sized particles through assembly and merging within the same self-assembly validates the non-classical growth. This strategy has been successfully extended towards the seed mediated growth reaction of AuNP in presence of three bio-inspired decameric peptides having varying number of Met residues. The study confirms the nucleation strategy even in presence of single Met residue in the peptide and also the self-assembly of nucleated particles with increasing Met residues within the peptide.

Methionine-stabilized nonclassical growth within self-assembled de novo gold nanoparticles in conjunction with secondary nucleation inhibition

The key steps for seed mediated growth of noble metal nanoparticles involve primary and secondary nucleation, which depends upon the energy barrier and ligand supersaturation standards of the medium. Herein we report the unique case of methionine (Met) controlled growth reaction, which rather proceeds via impeding secondary nucleation in presence of citrate stabilized gold nanoparticle (AuNP). The interaction between freshly generated Au+ and thioether group of Met in the medium restricts the secondary nucleation process involving further Au+ reduction. This incomplete conversion of Au+ results in a significant enhancement of the zeta (ζ) potential even at low concentration of Met. Furthermore, the aurophilic interaction of Au+ controls the self-assembly process of the in situ generated emissive nucleated particles. Nucleation of primary particles on seed surface, their segregation and time dependent conversion to larger particles within self-assembly confirm the nonclassical growth, which has further been explored with Met containing bio-inspired peptides.

Multidisciplinary study on the hydrogelation of digold(I) complex [{Au(9N-adeninate)}2(μ-dmpe)]: optical, rheological, and quasi-elastic neutron scattering perspectives

Herein, the syntheses of [{Au(9N-adeninate)}2(μ-dmpe)] (2, dmpe = 1,2-bis(dimethylphosphino)ethane) and its chloride precursor [(AuCl)2(μ-dmpe)] (1) are described. X-ray diffraction of 2 reveals a short intramolecular aurophilic interaction (2.9919(8) Å), which...

Control of aurophilic interaction: conformations and electronic structures of one-dimensional supramolecular architectures

Experimental and theoretical studies demonstrated that higher-ordered structures of one-dimensional aurophilic chains directly influenced their electronic structures.

Aurophilicity under pressure: a combined crystallographic and in situ spectroscopic study

High pressure crystallographic studies on [1,4-C6H4{PPh2(AuCl)}2] reveal the largest pressure-induced contraction of an aurophilic interaction observed for any Au(i) complex and further analysis confirms the presence of several types of intermolecular interactions.

Stepwise isolation of an unprecedented silylene supported dinuclear gold(i) cation with aurophilic interaction

Isolation of the first Si(ii) supported dinuclear Au(i) cation with an intramolecular Au⋯Au interaction of 2.875(1) Å has been realized.

Crystal structure of bis[μ-bis(diphenylphosphanyl)methane-κ2P:P′]digold(I) dichloride acetone monosolvate monohydrate

In the title complex salt, [Au2{(C6H5)2PCH2P(C6H5)2}]Cl2·(CH3)2C=O·H2O, the dication forms an eight-membered {—PCPAu}2ring with a transannular aurophilic interaction [Au...Au = 2.9743 (2) Å]. The ring approximates a flattened boat conformation, with the two methylene C atoms lyingca0.58–0.59 Å above the least-squares plane defined by the Au2P4atoms (r.m.s. deviation = 0.0849 Å). One Cl−anion functions as a weak bridge between the AuIatoms [Au...Cl = 2.9492 (13) and 2.9776 (12) Å]. The second Cl−anion forms two (water)O—H...Cl hydrogen bonds about a centre of inversion, forming a centrosymmetric eight-membered {...HOH...Cl}2supramolecular square. Globally, the dications and loosely associated Cl−anions assemble into layers lying parallel to theacplane, being connected by C—H...Cl,π(phenyl) interactions. The supramolecular squares and solvent acetone molecules are sandwiched in the inter-layer region, being connected to the layers on either side by C—H...Cl,O(acetone) interactions.