Organic functionalization of graphene is successfully performed via 1,3-dipolar cycloaddition of azomethine ylide in the liquid phase. The comparison between 1-methyl-2-pyrrolidinone and N,N-dimethylformamide as dispersant solvents, and between sonication and...

An effort to synthesize Cu(I)-variant of a leadfree double perovskite isostructural with Cs2AgInCl6 resulted in the formation of Cs3Cu4In2Cl13 nanocrystals with an unusual structure, as revealed by singlenanocrystal 3D electron diffraction. These nanocrystals adopt a A2BX6 structure (K2PtCl6-type, referred to as vacancy ordered perovskite) with tetrahedrallycoordinated Cu(I) ions. In the structure, 25% of the A sites are occupied by [Cu4Cl] 3+ clusters (75% by Cs +), and the B sites are half-occupied by In 3+. Such Cs3Cu4In2Cl13 compound prepared at the nanoscale is not known in the bulk and is an example of a multinary metal halide with inorganic cluster cations residing in A sites. The stability of the compound and a direct but parity forbidden bandgap are supported by density functional theory calculations. The existence of Cs3Cu4In2Cl13 structure demonstrates that small inorganic cluster cations can occupy A sites in multinary metal halides, paving the way for a new class of materials. ASSOCIATED CONTENT Supporting Information. Elemental analyses, XPS spectra, XRD patterns, TEM-EDS maps, dark-field STEM images, 3D ED refinement, electron diffraction patterns of a single and a twinned nanocrystal, details of Rietveld refinement (PDF). Crystal structures of Cs3Cu4In2Cl13 from 3D ED and Rietveld refinement (CIF).

We report the colloidal synthesis of bismuth chalcohalide nanocrystals, which adopt a hexagonal phase that we describe with the Bi13S18X2 (in which X = Br and I) structure. Such a model structure displays columns of Bi atoms that form dimers of subvalent Bi (formally Bi2 4+), which we here ascribe to Peierls-type distortions. We suggest that the Bi2 4+ dimers are at the origin of the anomalously low band gap of this material, with the lowest energy electronic transition showing analogies with an intervalence charge transfer. Our synthetic approach and insights into the structural and electronic features of the hexagonal bismuth chalcohalides are fundamental to sustain the rapidly increasing use of this class of (nano)materials for diverse applications, such as photocatalysis and thermoelectrics.