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Gold superatoms modified by chiral ligands are a new class of chiroptical nanomaterials, but improvement of their chiroptical properties, such as circular dichroism (CD) and circularly polarized luminescence (CPL), remains a challenge. In this work, we studied the effects of single-atom doping on the chiroptical properties of a representative Au-13 superatom using [Au-13((R,R)-DIPAMP)(5)Cl-2](3+) and [Au-13((S,S)-DIPAMP)(5)Cl-2](3+) (Au-13-R/S; DIPAMP = 1,2-bis[(2-methoxyphenyl)phenylphosphino]ethane). We synthesized an enantiomeric pair of superatoms: [IrAu12((R,R)-DIPAMP)(5)Cl-2](+) and [IrAu12((S,S)-DIPAMP)(5)Cl-2](+) (IrAu12-R/S). Single-crystal X-ray diffraction analysis revealed that the icosahedral Ir@Au-12 core of IrAu12-R/S was more twisted along the Cl-Au-Ir-Au-Cl axis compared with the Au-13 core of Au-13-R/S, leading to a larger absorption anisotropy factor. IrAu12-R/S exhibited a much higher photoluminescence quantum yield (similar to 70%) compared with Au-13-R/S (15%) due to a larger energy gap between the highest occupied and the lowest unoccupied molecular orbitals. Although Ir doping did not appreciably enhance the photoluminescence anisotropy factors, the brightness of the CPL of IrAu12-R/S was five times higher than that of Au-13-R/S. This work provides a rational guide for improving the chiroptical activity of Au superatoms via the doping-mediated manipulation of the geometric and electronic structures.

Fusion materials based on cationic gold nanoparticles mixed with ionic liquids were prepared. An anion exchange of the surface-capping ligand on the gold nanoparticles from a halogen anion to bis(trifluoromethanesulfonyl)amide (Tf2N) in an aqueous solution afforded nanoparticles showing infinite miscibility with Tf2N-based ionic liquids. The thermal decomposition temperature of the gold nanoparticle was elevated by 100[thinsp][deg]C after the anion-exchange process. The ionic liquid-like structure of the surface-capping ligand with Tf2N anions led to a glassy solid material with a densely packed assembly of nanoparticles, in which a portion of nanoparticles formed superlattices. A fusion material of ionic liquid and gold nanoparticles with a gold content as high as 40[thinsp]wt% was obtained by the co-solvent evaporation method using acetone. The stable dispersion of gold nanoparticles in the fusion materials with a high gold content was confirmed by the clear appearance of the plasmon absorption of gold nanoparticles in an optical microscopic image, as well as in an absorption spectrum. The use of an ionic liquid-based monomer yielded a gold nanoparticle-ionic liquid polymer composite, in which the gold nanoparticles showed a high thermal stability.

On–off photoswitching of circularly polarized luminescence was achieved using a pyrene-bearing helical tetrathiazole, in which two pyrene fluorophores stack in a chiral fashion (folded state). The pyrene-excimer based CPL was reversibly controlled by a geometrical change of the tetrathiazole upon photoisomerization.

One-dimensional (1D) self-assemblies of nanocrystals are of interest because of their vectorial and polymer-like dynamic properties. Herein, we report a simple method to prepare elongated assemblies of semiconductor nanorods (NRs) through end-to-end self-assembly. Short-chained water-soluble thiols were employed as surface ligands for CdSe NRs having a wurtzite crystal structure. The site-specific capping of NRs with these ligands rendered the surface of the NRs amphiphilic. The amphiphilic CdSe NRs self-assembled to form elongated wires by end-to-end attachment driven by the hydrophobic effect operating between uncapped NR ends. The end-to-end assembly technique was further applied to CdS NRs and CdSe tetrapods (TPs) with a wurtzite structure.

Thiocholine bromide was proposed as a cationic capping ligand for a variety of metal and semiconductor nanoparticles with a good dispersibility in an ionic liquid (IL). The stability of NPs was improved in the IL compared to that in water, which was verified by an improved emission property of semiconductor nanoparticles and higher thermal stability of gold nanoparticles. The cationic thiocholine was further demonstrated as a surface ligand for CdTe nanoparticle dispersible in organic media in combination with various anions.Thiocholine bromide was proposed as a capping ligand for a variety of metal and semiconductor nanoparticles with a good dispersibility in an ionic liquid. The cationic thiocholine further served as a surface ligand for CdTe NPs dispersible in organic media in combination with various anions.