Structural diversity in the coordination of 1,4-dihydro-1,4-diarsinine as a cyclic ditopic organoarsenic ligand to metal ions

Molecular gold strings: aurophilicity, luminescence and structure-property correlations

This review covers the compound class of one-dimensional gold strings. These compounds feature a formally infinite repetition of gold complexes as monomers/repeating units that are held together by aurophilic interactions, i.e. direct gold-gold contacts. Their molecular structures are primarily determined in the solid state using single crystal X-ray diffraction. The chemical composition of the employed gold complexes is diverse and furthermore plays a key role in terms of structure characteristics and the resulting properties. One of the most common features of gold strings is their photoluminescence upon UV excitation. The emission energy is often dependent on the distance of adjacent gold ions and the electronic structure of the whole string. In terms of gold strings, these parameters can be fine-tuned by external stimuli such as solvent, pH value, pressure or mechanical stress. This leads to direct structure-property correlations, not only with regard to the photophysical properties, but also electric conductivity for potential application in nanoelectronics. Concerning these correlations, gold strings, consisting of self-assembled individual complexes as building blocks, are the ideal compound class to look at, as perturbations by an inhomogeneity in the ligand sphere (such as the end of a molecule) can be neglected. Therefore, the aim of this review is to shed light on the past achievements and current developments in this area.

The Dawn of Functional Organoarsenic Chemistry

Organoarsenic chemistry was actively studied until the middle of 20th century. Although various properties of organoarsenic compounds have been computationally predicted, for example, frontier orbital levels, aromaticity, and inversion energies, serious concern to the danger of their synthetic processes has restricted experimental studies. Conventional synthetic routes require volatile and toxic arsenic precursors. Recently, nonvolatile intermediate transformation (NIT) methods have been developed to safely access functional organoarsenic compounds. Important intermediates in the NIT methods are cyclooligoarsines, which are prepared from nonvolatile inorganic precursors. In particular, the new approach has realized experimental studies on conjugated arsenic compounds: arsole derivatives. The elucidation of their intrinsic properties has triggered studies on functional organoarsenic chemistry. As a result, various kinds of arsenic-containing π-conjugated molecules and polymers have been reported for the last few years. In this minireview, progress of this recently invigorated field is overviewed.

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

Gold(i) chloride complexes with the diarsenic ligands cis-1,4-dihydro-1,4-diarsinines (cis-DHDAs) were synthesized. X-ray diffraction revealed that they formed one-dimensional polymeric structures through aurophilic interactions. Their higher-ordered structures are controlled by the ligand structure; methyl- and t-butyl substituted ligands offered transoid-transoid and transoid-cisoid conformations, respectively. Density functional theory (DFT) calculations indicated that the electronic structure of the aurophilic network was highly dependent on the conformations. This is the first study on the relationship between the chain conformation and 5d-orbital structures of gold complexes.

As-stereogenic C2-symmetric organoarsines: synthesis and enantioselective self-assembly into a dinuclear triple-stranded helicate with copper iodide

As-stereogenic C₂-symmetric organoarsines were safely synthesized from non-volatile precursors. The racemic mixture of the As-stereogenic ligands was enantioselectively self-assembled into a dinuclear triple-stranded helicate.