Stronger-together: the cooperativity of aurophilic interactions

Crystallographic distances and the electron density of bi- and tri-nuclear gold(I) compounds reveal that the existence of multiple Au···Au interactions increases their individual strength in the order of 0.9-2.9 kcal·mol-1....

Aggregation-Enhanced Room-Temperature Phosphorescence from Au(I) Complexes Bearing Mesogenic Biphenylethynyl Ligands

Gold(I) complexes, enabling to form linear coordination geometry, are promising materials for manifesting both aggregation-induced emission (AIE) behavior due to strong intermolecular Au–Au (aurophilic) interactions and liquid crystalline (LC) nature depending on molecular geometry. In this study, we synthesized several gold(I) complexes with rod-like molecular skeletons where we employed a mesogenic biphenylethynyl ligand and an isocyanide ligand with flexible alkoxyl or alkyl chains. The AIE behavior and LC nature were investigated experimentally and computationally. All synthesized gold(I) complexes exhibited AIE properties and, in crystal, room-temperature phosphorescence (RTP) with a relatively high quantum yields of greater than 23% even in air. We have demonstrated that such strong RTP are drastically changed depending on the crystal-size and/or crystal growth process that changes quality of crystals as well as the aggregate structure, of e.g., Au–Au distance. Moreover, the complex with longer flexible chains showed LC nature where RTP can be observed. We expect these rod-like gold(I) complexes to have great potential in AIE-active LC phosphorescent applications such as linearly/circularly polarizing phosphorescence materials.

Investigation of Solvatomorphism and Its Photophysical Implications for Archetypal Trinuclear Au3(1-Methylimidazolate)3

A new solvatomorph of [Au3(1-Methylimidazolate)3] (Au3(MeIm)3)—the simplest congener of imidazolate-based Au(I) cyclic trinuclear complexes (CTCs)—has been identified and structurally characterized. Single-crystal X-ray diffraction revealed a dichloromethane solvate exhibiting remarkably short intermolecular Au⋯Au distances (3.2190(7) Å). This goes along with a dimer formation in the solid state, which is not observed in a previously reported solvent-free crystal structure. Hirshfeld analysis, in combination with density functional theory (DFT) calculations, indicates that the dimerization is generally driven by attractive aurophilic interactions, which are commonly associated with the luminescence properties of CTCs. Since Au3(MeIm)3 has previously been reported to be emissive in the solid-state, we conducted a thorough photophysical study combined with phase analysis by means of powder X-ray diffraction (PXRD), to correctly attribute the photophysically active phase of the bulk material. Interestingly, all investigated powder samples accessed via different preparation methods can be assigned to the pristine solvent-free crystal structure, showing no aurophilic interactions. Finally, the observed strong thermochromism of the solid-state material was investigated by means of variable-temperature PXRD, ruling out a significant phase transition being responsible for the drastic change of the emission properties (hypsochromic shift from 710 nm to 510 nm) when lowering the temperature down to 77 K.

Recent Progress on Supramolecular Luminescent Assemblies Based on Aurophilic Interactions in Solution

The development of supramolecular systems showing aurophilic interactions in solution is gaining much attention in the last years. This is due to the intriguing photophysical properties of gold(I) complexes, which usually confer to these supramolecular assemblies interesting luminescent properties, as well as the possibility of morphological modulation, through fine tuning of inter- and intramolecular aurophilic interactions, in synergy with the formation of other supramolecular contacts. In this work, an overview of the advances made in this area since 2015 is presented. A large variety of systems showing different spectroscopical and structural topologies has been reported. Moreover, these supramolecular assemblies have proven to be useful in a wide range of applications.

Intramolecular aurophilic interactions in dinuclear gold(i) complexes with twisted bridging 2,2′-bipyridine ligands

Five new luminescent dinuclear gold(i) complexes with an atypical twisted bridging 2,2′-bipyridine ligand have been obtained and structurally characterized. The structures of these gold complexes have some similarities with a crab body.

Metallophilicity-Induced Clusterization: Single-Component White-Light Clusteroluminescence with Stimuli Responses

<p>The single-component white-light-emitting materials play an essential role in the next-generation solid-state lighting technology. Herein, linear gold(I) complex TPPGPA with conglobate trimer configuration trigged by aurophilic interactions in crystalline state was prepared to emit dual phosphorescent white-light emission, which also exhibited multi-stimuli responsive luminescent properties including thermochromism and mechanochromism. Specifically, the molecular packing mode and aurophilic interactions regulation were subtly taken as a functional relationship of the experimental correlation with emission. The results showed that the regulated aurophilic interactions and restriction of molecular motion were determined to be the precipitating factor and as a function of the wavelength and intensity, which is significant for the design guide about intelligent stimuli-responsive white-light emissive luminescent materials. Furthermore, their application in temperature-responsive white-light illumination was successfully demonstrated. </p>

Metallophilicity-Induced Clusterization: Single-Component White-Light Clusteroluminescence with Stimuli Responses

<p>The single-component white-light-emitting materials play an essential role in the next-generation solid-state lighting technology. Herein, linear gold(I) complex TPPGPA with conglobate trimer configuration trigged by aurophilic interactions in crystalline state was prepared to emit dual phosphorescent white-light emission, which also exhibited multi-stimuli responsive luminescent properties including thermochromism and mechanochromism. Specifically, the molecular packing mode and aurophilic interactions regulation were subtly taken as a functional relationship of the experimental correlation with emission. The results showed that the regulated aurophilic interactions and restriction of molecular motion were determined to be the precipitating factor and as a function of the wavelength and intensity, which is significant for the design guide about intelligent stimuli-responsive white-light emissive luminescent materials. Furthermore, their application in temperature-responsive white-light illumination was successfully demonstrated. </p>

Crystal structure of the unusual coordination polymer catena-poly[[gold(I)-μ-1,2-bis(diphenylphosphinothioyl)ethane-κ2 S:S′] dibromidoaurate(I)]

In the title compound, {[Au(C26H24P2S2)][AuBr2]} n , the gold(I) centres of the cation are coordinated by the P=S groups of the disulfide ligands to form a chain polymer parallel to the c axis. Both independent gold atoms lie on the same twofold axis, and the midpoint of the H2C—CH2 bond lies on an inversion centre. The anions flank the polymeric chain; they are connected to it by short aurophilic interactions and C—H...Br contacts, and to each other by Br...Br contacts.