Three-dimensional organization of d- or l-tryptophan and mercaptopropionic acid-stabilized gold nanoclusters has been achieved by complexation of ligands using zinc ions. Powder X-ray diffraction and transmission electron microscopy analyses substantiated the crystalline nature of the assembly of atomic nanoclusters. The hierarchical arrangement of the nanoclusters exhibited superior optical properties (namely, enhanced photoluminescence and excited-state lifetime) as compared to the non-assembled nanoclusters. Furthermore, photoluminescence of the crystalline assembly of nanoclusters served as a visual marker for chiral recognition of d and l enantiomers of tryptophan, with subsequent separation of the corresponding enantiomer. A theoretical structure based on various experimental observations has also been proposed herein. The mechanistic aspect of the chiral separation is proposed to have occurred through attachment of d or l-tryptophan to the coordinatively unsaturated zinc ions, thus forming super complexes. The degree of stabilization of the super complexes is dictated by a "three-point versus two-point" interaction between the enantiomers and the chiral selector.
We report that complexation-reaction-mediated two-dimensional crystalline assembly of gold (Au 14 ) nanoclusters (NCs) exhibits room-temperature delayed fluorescence at 605 nm, with an unprecedented long lifetime of 0.5 ms and an exceptionally high quantum yield of 19.1 ± 0.9%. Interestingly, the as-synthesized Au NCs had a very weak delayed fluorescence signal. The enhancement in delayed fluorescence of Au NCs upon formation of assembly has been attributed to the crystallizationinduced structural rigidity, which restricted the nonradiative transitions and enhanced the excited-state lifetime. The attainment of crystalline organization was substantiated by electron diffraction analysis. A possible structure was established based on experimental results and computational optimizations. Atomic force microscopy revealed the formation of multilayered two-dimensional nanosheets with thickness of 2.44 ± 0.48 nm.
Herein we report unprecedented determination of molar mass of zinc mediated assemblies of homoleptic gold nanoclusters, based on charge detection mass spectrometry measurements. The accurate determination of molar mass of...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.