This work focusses on weak NH & ctdot;Au(i) non-covalent interactions (NCIs), a subject of ongoing debate. It reports the synthesis and characterization of new gold(i) complexes featuring the pincer ligand N,N '-bis{(2-diphenylphosphanyl)phenyl}-2,6-pyridinedicarboxamide (L). Rare examples of N(amide)H & ctdot;Au(i) interactions in different coordination environments are examined. In the neutral complex [Au(L-H)] (3), both a directional N(amide)H & ctdot;Au(i) contact consistent with a metal-centered hydrogen bond and an uncommon secondary N(amidate)& ctdot;Au(i) interaction are identified, highlighting their relevance for future structural and computational analyses.

Unsupported Au⋯Pd interactions have not yet been experimentally confirmed, leaving their existence and fundamental nature an open question. Herein, we present a comprehensive multifaceted computational study to grasp their nature and feasibility, using simplified models of typical Au(I)/Au(III) and Pd(II) complexes. Geometry optimizations and interaction energy calculations were carried out at both the DFT and post-Hartree-Fock levels of theory, including MP2, SCS-MP2 and DLPNO-CCSD(T) methods. Potential energy curves computed at the MP2 and RHF levels of theory with different relativistic ECPs allowed us to disentangle the effects of electron correlation and relativistic contributions. In-depth topological analyses based on MP2 and DLPNO-CCSD(T) electron densities were conducted to gain deeper insight into the bonding character. Additionally, we also propose a decomposition scheme to isolate the metal-metal contribution to the total interaction energy; a term whose true nature, repulsive or attractive, remains debatable. This computational protocol, together with the reduced size of the simplified models, provides a consistent and reliable framework for the high-accuracy characterization of metallophilic interactions. Remarkably, the computed Au⋯Pd interaction energy values are stronger than anticipated (10-35 kJ mol-1), with a predominantly ionic and dispersive, closed-shell character and a minor covalent contribution. In these systems, medium-to-strong metal-hydrogen interactions are also present, coexisting and competing with the metallophilic contacts to influence the overall stabilization. Collectively, our results point to the potential existence of related compounds featuring unsupported Au⋯Pd contacts in suitably designed systems, where substantial electrostatic forces further stabilize the models.

Emissive properties of diphosphino-gold( i ) complexes displaying tunable TADF behaviour are strongly influenced by the electronic structure of the ligands. ONIOM calculations at the ADC(2):QM/MM level enable modeling of gold-based emitters.

Half-sandwich iridium complexes exhibit poor photophysical properties. We reported the first case of half-sandwich cyclometalated iridium complexes with anticancer photodynamic activity, using two π-expansive ligands differing by one extra ring in [Cp*Ir(C^N)L]BF4 complexes. Considering the ability of the ligands to aggregate through π-π interactions, which may reduce the emission energy, and the interest in NIR emitters, we envisaged to study the concentration-dependent solution and solid state photophysical properties. Besides emission, aggregation was verified by 1H NMR, PFGSE-DOSY NMR experiments, X-ray diffraction, and DLS. It was found by X-ray diffraction the formation, with pair of enantiomers, of head-to-tail dimers that were further aggregated in some cases. The complexes with L = N-benzylimidazole became NIR emitters in solid state with a red-shift for the more π-expansive complex. The less π-expansive complex exhibited aggregation-enhanced emission. A significant effect on the emission of the additional ring was observed, that is explained by the stronger distortion of the excited state of the more π-expansive complex that favors disaggregation in solution. These are the first reported half-sandwich derivatives of any metal to exhibit NIR emission. DFT and TD-DFT studies support the experimentally observed features through the study of dinuclear model systems displaying π-π stacking interactions.

Abstract We report a combined spectroscopic, kinetic, and computational study of aggregation-induced emission (AIE) in tetranuclear Au(I)/Ag(I) complexes in microheterogeneous acetonitrile/water mixtures. Time-resolved UV–vis spectroscopy and multivariate analysis reveal that once AIE aggregates are formed, a further aggregation process proceeds via a continuous, cooperative reorganization pathway rather than classical nucleation–growth. The process follows compressed-exponential kinetics and exhibits a well-defined activation barrier (Ea = 86 kJ·mol–1). Dynamic light scattering confirms a hierarchical growth from nanometric aggregates to micron-scale species leading to precipitation. DFT calculations show that interunit interactions (116 kJ·mol–1), dominated by aurophilic and π-stacking forces, govern aggregate stability and are mechanistically linked to the kinetic barrier arising from their partial reorganization. Conductor-like Screening Model (COSMO) analysis further indicates weak solvation, rationalizing the dominance of intermolecular interactions.

Metallophilic interactions remain controversial despite decades of study. This perspective highlights computational progress, unresolved questions, and challenges that continue to inspire the field.

This work presents the synthesis, structural characterization, and photophysical studies of a new gold-(I)-lead-(II) heterometallic polymeric complex, [{Au-(C6F5)2}2{Pb-(S-Terpy)}] n , and its solvatopolymorphs incorporating acetone and diethyl ether. The complex exhibits reversible solvatochromic behavior with significant changes in color and luminescence upon solvent inclusion. X-ray diffraction reveals that the trinuclear Au-Pb-Au units are maintained across all solvatopolymorphs, although the packing and intermetallic distances vary depending on the solvent and its coordination mode. Optical studies show that the complexes emit in the visible to near-infrared region, with emission properties strongly influenced by the nature of the solvent. DFT and TD-DFT reveal that the emission arises from metal-to-ligand or ligand-to-ligand charge transfer transitions, depending on the structure. These results highlight the potential of gold-lead supramolecular systems as responsive luminescent materials for sensing applications.

By reaction of the polymers [Au2Ag2(C6X5)4(OEt2)2]n (X = F, Cl) with the aromatic N-donor ligands pyrimidine and pyrazine, the new heterometallic complexes [Au2Ag2(C6X5)4(pym)]n (X = F (1), Cl (2)) and [Au2Ag2(C6X5)4(pyr)(CH3CN)2]n (X = F (3), Cl (4)) are obtained. The crystal structures of complexes 1 and 3 show the polymerization of the Au2Ag2 tetranuclear units via diazine bridging ligand between two silver centers, and also, in case of complex 1 via aurophilic interactions, leading to a two-dimensional polymer. In all cases, the optical properties have been studied in solid state at room temperature and 77 K, showing lifetimes in the microseconds range. Finally, this study has been completed with time-dependent density functional theory calculations in the case of complexes 1 and 3 (which present two different emissions) to ascribe the origin of their emissive properties. The molecular orbitals involved in the electronic transitions responsible for the phosphorescence in the case of complex 1 are related to a ligand (C6F5) to ligand (pyrimidine) charge transfer (3LL'CT) and to a cluster metal-centered transition (3MM'). For complex 3, these molecular orbitals consist of a mixture of a ligand-metal to ligand charge transfer ([Au(C6F5)2]-pyrazine) (3LML'CT) and an intraligand transition (within the pyrazine ligand) (3IL).

This work introduces a new family of perhalophenylgold(I) compounds containing the asymmetric P,N-donor ligand (diphenylphosphino)aniline (PNH2), which acts as a monodentate P-donor ligand in the mononuclear gold(I) derivatives [AuR(PNH2)] [R = C6F5 (1), C6Cl2F3 (2), C6Cl5 (3), o-C6BrF4 (4)]. While all complexes share the same building blocks, the research focuses on understanding how these seemingly similar molecules pack differently in their crystal structures. We employ density functional theory (DFT) calculations to analyze the intra- and intermolecular interactions responsible for these distinct arrangements. These interactions include weak N-H⋯Au bonds within a molecule, along with hydrogen bonds or π-stacking between aromatic rings of neighboring molecules.

Thiolate-protected gold nanoclusters (AuNCs) of sub-2 nm size have been synthesized through a novel bottom-up approach using the organometallic precursor [Au(C6F5)(tht)] (tht = tetrahydrothiophene) in a one-pot reaction under mild conditions. This protocol is simple, rapid (1 h), versatile (applicable to thiolate ligands of varying molecular sizes), and reproducible, yielding AuNCs with low size dispersion. Furthermore, the resulting nanomaterials exhibited remarkable catalytic activity, effectively reducing the pollutant 4-nitrophenol to 4-aminophenol, as well as promising photothermal and photodynamic properties upon exposure to an 808 nm laser, converting light into thermal energy and generating reactive oxygen species (ROS). Additionally, AuNCs stabilized with a nonapeptide demonstrated efficient catalase-like activity, thereby potentially enhancing the efficacy of photodynamic therapy. The cytotoxic effects against cancer (HeLa) and healthy cells (HDF) were also evaluated, showing greater selectivity for HeLa cells, with higher toxicity and increased ROS generation.

Unsupported metallophilic interactions remain experimentally unexplored in gold-iridium heterobimetallic complexes. To address this gap, we conducted a computational study on a series of model systems of the form [Ir(CO)X(PH3)2][AuR2], where X = Cl, Br, and I and R = H, CH3, NH3, and PH3, to evaluate their strength and feasibility. Optimizations were performed at the MP2/def2-TZVPP level of theory, and interaction energies at equilibrium distances were assessed through potential energy curves (PECs). To account for relativistic effects, calculations were complemented by spin-component-scaled (SCS)-MP2 within the zero-order regular approximation (ZORA). Further insight into the nature of these interactions was gained through analyses of NBO effective charges, bond orders, natural energy decomposition analysis (NEDA), and topological examination of electron density using QTAIM and IGMH frameworks. Our results revealed intermetallic distances consistent with significant noncovalent attraction, exhibiting unexpectedly high interaction energy values (20-60 kJ mol-1). The presence of a bond critical point (BCP) along the Au(I)···Ir(I) bond path across all model systems confirms the attractive character of these interactions, which are characterized as regular closed-shell with a partial degree of electron sharing. Overall, this study underscores the potential importance of such noncovalent interactions in the rational design of unsupported gold-iridium heterobimetallic complexes with promising properties.

We have computationally studied the attraction between gold and platinum atoms in a series of unsupported model systems with formulas cis/trans-[Pt(CH3)2(NH3)2][Au(CH3)3(NH3)] (1a/1b), cis/trans-[Pt(CH3)2(NH3)2][Au(CH3)(NH3)] (2a/2b), [Pt(CH3)(NH3)3][Au(CH3)2] (3), and {[Pt(NH3)4][Au(CH3)2]}+ (4). These systems stem from the simplification of the well-known orthometalated complexes of these metals, allowing for a clearer-as-possible description of the metallophilic interaction while reducing computation cost and keeping chemical representativeness. To achieve this goal, we fully optimized the model systems at the MP2 level of theory with the def2-TZVP basis sets. We analyzed the interaction energy at equilibrium distances through potential energy curves at the RHF and MP2 levels of theory, employing different relativistic pseudopotentials. Additionally, we examined various parameters, including natural bonding orbital effective charges or bond orders, and conducted an in-depth topological analysis of the electron density. The Au···Pt interaction has been characterized as a regular closed-shell interaction with some degree of electron sharing, but weaker (ca. 15 kJ·mol-1) than other metallophilic interactions, such as Au···Au or Au···Hg. Overall, this study sheds light on the key factors influencing the Au···Pt interaction.

The polymeric linear chain [AuTl(C6Cl5)2]n reacts with three terpyridine-type ligands substituted with thiophene groups containing N-donor centres in different relative positions (L1, L2 and L3), leading to the Au(I)/Tl(I) complexes [AuTl(C6Cl5)2(L1)]n (1), [{AuTl(C6Cl5)2}2(L2)]n (2) and [AuTl(C6Cl5)2(L3)]n (3). X-Ray diffraction studies reveal that L1 acts as a chelate, while L2 and L3 act as bridging ligands, resulting in different coordination indexes for the thallium(I) centre. These structural differences strongly influence their optical properties, and while compounds 2 and 3 emit near the limit of the visible range, complex 1 emits in the infrared region. DFT calculations have also been carried out in order to determine the origin of the electronic transitions responsible for their optical properties.

Photophysical properties of the three-fold symmetric 2,5,8-tris(phenylthiolato)heptazine molecule (1) are studied from combined experimental and computational viewpoints. The intense blue photoemission of 1 in the solid state and in toluene solution is proposed to have a fluorescent origin on the basis of a relatively short emission lifetime and no detectable triplet decay. Calculations at correlated ab initio levels of theory also show that 1 has a large inverted singlet-triplet (IST) gap, a non-vanishing spin-orbit coupling matrix element between the first excited singlet and triplet states, and a fast intersystem crossing rate constant that leads to singlet population from the higher-lying triplet state. The IST gap implies that the first excited singlet state is the lowest excited one, agreeing with the measured fluorescent behaviour of 1. IST gaps are also obtained for the oxygen-containing (2) and selenium-containing (3) analogues of 1 at the ADC(2) level of theory, but not for the tellurium one (4). Calculations of the magnetically induced current density demonstrate that the heptazine core of 1 is globally non-aromatic due to the alternation of carbon and nitrogen atoms along its external rim. The calculated energy inversion of the first excited states of a heptazine phenylthiolate molecule is consistent with the intense blue fluorescence in the solid state and in toluene solution.

Polymers can serve as an effective matrix to stabilize gold nanoparticles. These materials offer a continuous light-activated supply of subnanoclusters, which are composed of a few atoms. We report an efficient approach to enhance the catalytic activity of gold subnanoclusters by in situ feeding of these species through the generation of hot carriers via 5d-6s6p interband transitions on PEG-stabilized Au nanoparticles.

Gold nanoparticles in different proportions (0.5 and 1 %) have been grafted at the surface of a SiO2@g-C3N4 2 @g-C 3 N 4 nanotube-based composite (SiO2 2 nanotubes obtained from halloysite clay) and also g-C3N4 3 N 4 (for comparison purposes) to test their degradation capacity over the antibiotic amoxicillin proving that the introduction of these nanoparticles on the catalyst modifies the degradation mechanism followed by the pollutant. Results obtained show that the introduction of the appropriate percentage of gold NPs in the composite improves amoxicillin degradation efficiency and establish a direct correlation between the presence of gold NPs and the production of & sdot;O2 2- .

The synthesis of gold(III) and gold(I)–gold(III) complexes with phosphide bridges is still a matter that requires solutions for their marked instability, in spite of the affinity of this metal in both oxidation states for phosphorous donor ligands. In the course of our studies, we realized that the presence of perhalophenyl groups of the type pentafluorophenyl or 3,5-dichlorotrifluorophenyl in the complexes gives rise to an increase in their stability that eases their isolation and structural characterization. In this paper, we describe two new fully characterized neutral compounds of this type to extend the knowledge on this family of compounds, [{Au(C6Cl2F3)2}2(µ-PPh2)2] (1) and [{Au(C6Cl2F3)2(µ-PPh2)2Au}2] (2). In this work, we analyze the role of the perhalophenyl groups in the stability of these complexes by using quantum chemical topology methodologies, specifically employing an analysis of the non-covalent interactions (NCIs) in real space and evaluating the electrostatic potential surfaces (ESP). Our findings reveal the existence of appreciable π-stacking interactions among the perhalophenyl and phenyl groups in both compounds, significantly contributing to the stability of the systems.

4-Nitrophenol (4-NP) is an organic contaminant attached to textiles, pharmaceuticals, and pesticides. Its presence has been increasingly detected in various water bodies such as lakes, rivers, and occasionally in drinking water. The present work shows the reduction of 4-NP using a hybrid catalytic system composed of gold and silver nanoparticles supported onto the biogenic porous silica (AgAu-SiO2). The AgAu nanoparticles were fabricated in situ onto the salinized biogenic silica substrates through a green synthesis. The catalytic reaction was analyzed with NaBH4 and the proposed AgAu-SiO2 catalyst. Mimicking 4-NP reduction reaction in different spiked river/marine water samples revealed superior catalytic activity in marine water. Subsequently, interference studies performed in the presence of different metal salts and pHs (found in the marine water) showed the vital role played by NaCl in the 4-NP reduction as the increase in the NaCl concentration enhances the catalytic activity of the proposed catalyst. Additional reusability of the proposed catalyst demonstrated its efficacy up to 10 cycles. The density functional theory (DFT) results supported the experimental findings, confirming the crucial role of Na+ and Cl- in the catalytic process. Our experimental results, which have significant implications for the field, have been explained by comparing them with DFT calculations. The main reason behind the enhanced catalysis performance in our systems was deduced at the atomic scale. The study included the adsorption energies and electronic density of molecular structures (4-NP and 4-AP) on different surface coverages. In exceptional cases, at the intermediate of 4-NP on Au(111)-NaCl, a displacement of the electronic density is observed, leading to a quinoline-type ring weakening the N-O bond and favoring the catalytic performance.