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Multi‐resonance (MR) type emitters have emerged as highly promising candidates for high‐resolution organic light‐emitting diodes (OLEDs). However, thermally activated delayed fluorescence (TADF) emissions with simultaneous short excited state lifetimes and ultrapure blue color (a CIEy close to 0.046 and an emission peak >440 nm) have rarely been obtained for MR emitters. Herein, we report a design of dual gold‐coordinated MR molecules to achieve efficient and short‐lived ultrapure blue TADF emission. The dinuclear Au(I) complex, namely iPrAuBN, shows a narrowband deep‐blue emission with a peak maximum of 448 nm and a full width at half maximum (FWHM) of 29 nm in doped film. The coordination with two Au atoms significantly shortens the delayed fluorescence lifetime to 7.8 μs in comparison to 60.6 μs for the parental organic analogue. Solution‐processed OLED doped with iPrAuBN demonstrates an ultrapure blue electroluminescence with a peak maximum of 442 nm, a FWHM of 19 nm, CIE coordinates of (0.154, 0.036), and a maximum external quantum efficiency of 14.8 %. [ABSTRACT FROM AUTHOR]

To study the effect of a dye on the photoluminescence (PL) properties of metal complexes, a series of gold(I) complexes were synthesized, containing a 7‐amino‐4‐methylcoumarin luminophore. The complexes are comprised of a coumarin moiety featuring different ancillary ligands, specifically N‐heterocyclic carbenes, triphenylphosphine, and diphenyl‐2‐pyridylphosphine. The synthesized gold(I) complexes are luminescent both in solution and the solid state at room temperature and 77 K. Complexes of different nuclearity, i.e., mono‐, di‐ and trinuclear compounds were synthesized. A clear trend between the nuclearity and the quantum yields can be seen. The coumarin dye not only improves the PL properties, but also enhances the luminescence of trinuclear clusters, which are otherwise known to be weak emitters in solution. The optical absorption properties were investigated in detail by quantum chemical calculations. [ABSTRACT FROM AUTHOR]

Interactions between gold‐based materials and dioxygen (O2) have motivated researchers to understand reaction mechanisms for O2 activation by homo‐ and heterogeneous gold catalysts. In this work, gold(I) porphyrin dinuclear complexes were synthesized with a saddle‐distorted porphyrin ligand. The gold(I) porphyrin complexes showed unprecedented O2 activation in the presence of protic solvents to form gold(III) tetradentate porphyrin complexes. Mechanistic insights into the O2 activation by the gold(I) center were elucidated by spectroscopic measurements and theoretical calculations, revealing that dissociation of halides on the gold(I) center by alcohol solvents and hydrogen bonding of an N−H proton in the distorted porphyrin with dioxygen played important roles in establishing the unique reactivities of gold(I) complexes. [ABSTRACT FROM AUTHOR]

[Display omitted] Transition metal complexes of copper subgroup metals are actively studied objects for temperature sensors. Their luminescence arising from the 3ILCT, 3MLCT or 3CC excited states is characterized by emission in all ranges of visible spectra and high quantum yields. Due to the ability of the complexes to emit in a dual band mode, these complexes are attractive for the temperature sensing in the ratiometric mode. Dual emission of complexes is usually susceptible of the irregular changes in intensity of two emission bands during the temperature changes. This is an important and necessary property for the utilization of phosphors as ratiometric thermometers. The structures and emission properties of gold(i) and copper(i) complexes are considered with the aim to demonstrate the possibility to apply such complexes as ratiometric molecular luminescent thermometers for the remote control of the object's temperature. [ABSTRACT FROM AUTHOR]

This work presents the synthesis and characterization of mono‐ (1) and di‐nuclear (2) imidazolium salts stabilized by [AuPPh3]+ fragments. The presence of the gold moiety induces a significant decrease in the carbenic proton's acidic character (high pKa). This high stability is consistent with the pronounced instability of the conjugate bases obtained through deprotonation using strong bases. The formation of carbene species is accompanied by the identification of a 1,2‐rearrangement process in which a preference for the C‐bound species over the N‐bound species is observed. Experimental techniques such as NMR, single‐crystal X‐ray diffraction analysis, mass spectrometry, and computational calculations are employed to investigate the reactivity exhibited by the imidazolium salts. Additionally, the electrochemical properties of the two imidazolium salts were also investigated. This study reveals that both species 1 and 2 display two cathodic peaks which are related to two electro‐chemical irreversible reduction events. The results obtained from both experimental and theoretical studies of this system reveal a strong tendency of the [AuPPh3]+ fragment to stabilize imidazolium salts. Additionally, they demonstrate the preference of this fragment for C‐bound species over N‐bound ones, with the former proving to be highly unstable even under severe conditions of air and moisture exclusion. [ABSTRACT FROM AUTHOR]

The following new compounds of gold(III) with 1,1-dimethylbiguanide (NH2C(=NH)NHC(=NH)N(CH3)2) are prepared and studied by XRD: [Au(dmbgH)Cl2]Cl.0.5H2O, [Au(dmbgH)Cl2]ClO4.H2O, [Au(dmbgH) Cl2]ClO4, [Au(dmbg)Cl2][Au(dmbgH)Cl2]Cl.H2O (dmbgH = 1,1-dimethylbiguanide, dmbg = deprotonated 1,1-dimethylbiguanide). [ABSTRACT FROM AUTHOR]

Gold(III) complexes are widely studied as antitumor agents and show good results. The interaction with biologically active thiols (thiomalate, cysteine, glutathione (GSH) and human serum albumin) of a number of gold(III) complexes with N-containing polydentate ligands in aqueous solution with pH 7.4 and 0.2 M NaCl was studied. Complexes with 1,10-phenanthroline and 2,2′-bipyridyl, Au(phen)(OH)2+ and Au(bipy)(OH)2+, react fast with an excess of any of these thiols and in less than a few seconds transform into gold(I) bis-thiolate complexes. For complexes with deprotonated ethylenediamine and diethylenetriamine, Au(en)(en-H)2+ and Au(dien-H)(Cl,OH)+, at a significant excess of GSH, a relatively long-lived gold(III) complex AuIII(GSH)iLj is formed. At t = 37 °C, it transforms into the gold(I) bis-thiolate complex Au(GSH)2 by 90% in 4 h. However, for other thiols, the rate of decomposition of similar complexes is about 10 times higher. Some other complexes were also considered. In all cases, a fairly fast reduction of gold(III) to gold(I) occurs with the formation of the gold(I) bis-thiolates. [ABSTRACT FROM AUTHOR]

Two‐coordinate coinage metal complexes have emerged as promising emitters for highly efficient organic light‐emitting devices (OLEDs). However, achieving efficient long‐wavelength electroluminescence emission from these complexes remains as a daunting challenge. To address this challenge, molecular design strategies aimed at bolstering the photoluminescence quantum yield (Φ) of Au(I) complex emitters in low‐energy emission regions are investigated. By varying amido ligands, a series of two‐coordinate Au(I) complexes is developed that exhibit photoluminescence peak wavelengths over a broad range of 533−750 nm. These complexes, in particular, maintain Φ values up to 10% even in the near‐infrared emission region, overcoming the constraints imposed by an energy gap. Quantum chemical calculations and photophysical analyses reveal the action of radiative control, which serves to overcome the energy gap law, becomes more pronounced as the overlap between hole and electron distributions (Sr(r)) in the excited state increases. It is further elucidated that Sr(r) increases with the distance between the hole‐distribution centroid and the nitrogen atom in an amido ligand. Finally, multilayer OLEDs involving the Au(I) complex emitters exhibit performances beyond the borderline of the electroluminescence wavelength−external quantum efficiency space set by previous devices of coinage metal complexes. [ABSTRACT FROM AUTHOR]

A series of gold(I) monoisocyanide [AuCl(CNC6H4-4-X)] (X = Cl (IIa), Br (IIb), I (IIc) and bis-isocyanide [Au(CNC6H4-4-X)2](PF6) (X = Cl (IIIa), Br (IIIb), I (IIIc) complexes were prepared by the reaction of [AuCl(Tht)] (Tht = tetrahydrothiophene) with the specified isocyanide. The molecular structure of IIa–IIc was established by X-ray diffraction (CCDC no. 2253450 (IIa), 2253447 (IIb), 2253448 (IIc)). The crystals of IIb and IIc are isostructural; they were found to have several types of intermolecular interactions, particularly, C–X⋯Cl–Au halogen bonds, π-hole (CCNR)··· (Au) interactions, and Au⋯Au aurophilic contacts, which form together a two-layer 2D supramolecular polymer. The crystals of IIb, IIc and IIIa, IIIb exhibit phosphorescence at room temperature; compounds IIa and IIIc do not possess luminescent properties; and mechanical grinding of IIa‒IIc and IIIa‒IIIc powders does not change the photophysical properties. [ABSTRACT FROM AUTHOR]

Abstract Two‐coordinate coinage metal complexes have emerged as promising emitters for highly efficient organic light‐emitting devices (OLEDs). However, achieving efficient long‐wavelength electroluminescence emission from these complexes remains as a daunting challenge. To address this challenge, molecular design strategies aimed at bolstering the photoluminescence quantum yield (Φ) of Au(I) complex emitters in low‐energy emission regions are investigated. By varying amido ligands, a series of two‐coordinate Au(I) complexes is developed that exhibit photoluminescence peak wavelengths over a broad range of 533−750 nm. These complexes, in particular, maintain Φ values up to 10% even in the near‐infrared emission region, overcoming the constraints imposed by an energy gap. Quantum chemical calculations and photophysical analyses reveal the action of radiative control, which serves to overcome the energy gap law, becomes more pronounced as the overlap between hole and electron distributions (Sr(r)) in the excited state increases. It is further elucidated that Sr(r) increases with the distance between the hole‐distribution centroid and the nitrogen atom in an amido ligand. Finally, multilayer OLEDs involving the Au(I) complex emitters exhibit performances beyond the borderline of the electroluminescence wavelength−external quantum efficiency space set by previous devices of coinage metal complexes.

The worldwide increase in antibiotic resistance poses a significant challenge, and researchers are diligently seeking new drugs to combat infections and prevent bacterial pathogens from developing resistance. Gold (I and III) complexes are suitable for this purpose. In this study, we tested four gold (I and III) complexes, (1) chlorotrimethylphosphine gold(I); (2) chlorotriphenylphosphine gold(I); (3) dichloro(2-pyridinecarboxylate) gold (III); and (4) 1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene gold(I) chloride, for their antibacterial, antibiofilm, antiviral, and anti-quorum sensing activities. Results reveal that 1 significantly inhibits Escherichia coli DSM 1077 and Staphylococcus aureus ATCC 6538, while 2, 3, and 4 only inhibit S. aureus ATCC 6538. The minimum inhibitory concentration (MIC) of 1 for S. aureus ATCC 6538 is 0.59 μg/mL (1.91 μM), and for methicillin-resistant S. aureus strains MRSA 12 and MRSA 15, it is 1.16 μg/mL (3.75 μM). For E. coli DSM 1077 (Gram-negative), the MIC is 4.63 μg/mL (15 μM), and for multi-resistant E. coli I731940778-1, it is 9.25 μg/mL (30 μM). Complex 1 also disrupts biofilm formation in E. coli and S. aureus after 6 h or 24 h exposure. Moreover, 1 and 2 inhibit the replication of two enterobacteria phages. Anti-quorum sensing potential still requires further clarification. These findings highlight the potential of gold complexes as effective agents to combat bacterial and viral infections. [ABSTRACT FROM AUTHOR]

The prominent role of gold‐N‐heterocyclic carbene (NHC) complexes in numerous research areas such as homogeneous (photo)catalysis, medicinal chemistry and materials science has prompted organometallic chemists to design gold‐based synthons that permit access to target complexes through simple synthetic steps under mild conditions. In this review, the main gold‐NHC synthons employed in organometallic synthesis are discussed. Mechanistic aspects involved in their synthesis and reactivity as well as applications of gold‐NHC synthons as efficient pre‐catalysts, antitumor agents and/or photo‐emissive materials are presented. [ABSTRACT FROM AUTHOR]

Auranofin ([1-(thio-κS)-β-d-glucopyranose-2,3,4,6-tetraacetato](triethylphosphine)-gold) is a leading gold-based drug clinically used to treat arthritis. In the last years, it entered various drug reprofiling programs, and it has been found promising against various forms of tumor, including ovarian cancer. Evidence showed as its antiproliferative profile mainly depends on the inhibition of thioredoxin reductase (TrxR), being this mitochondrial system its main target. In this context, we report here the synthesis and biological evaluation of a novel complex designed as auranofin analogue obtained through the conjugation of a phenylindolylglyoxylamide ligand (which belongs to the so-called PIGA TSPO ligand family) with the auranofin-derived cationic fragment [Au(PEt3)]+. This complex is characterized by two parts. The phenylindolylglyoxylamide moiety, owing to its high affinity for TSPO (in the low nM range) should drive the compound to target mitochondria, whereas the [Au(PEt3)]+ cation is the actual anticancer-active molecular fragment. Overall, we wanted to offer the proof-of-concept that by coupling PIGA ligands to anticancer gold active moieties, it is possible to preserve and even improve anticancer effects, opening the avenue to a reliable approach for targeted therapy. [ABSTRACT FROM AUTHOR]

In the process of gold ores leaching by glycine and cyanide, the interactions between glycine and cyanide with metals are not well understood and there is little research in this area. The characterization of gold and copper complexes in the cyanide-glycine system by UV-Vis spectroscopy method is studied. Job’s method of continuous variation was applied to ascertain the stoichiometry composition of the complexes. The results showed that in the glycine-gold-copper system, although the stability constant of the gold-glycine complex is higher, the dominant species formed is the copper-glycine complex. In the cyanide-gold-copper system, gold forms complexes with cyanide and to a lesser extent glycine, which agrees with their stability constants. If the cyanide and glycine ligands are added to a gold solution, the dominant species in the system is the gold-cyanide complex. In the cyanide-glycine-copper system, the dominant species in the system is the copper-glycine complex. When cyanide and glycine ligands are added to a gold-copper solution, the dominant species in the system are the copper-glycine and the gold-cyanide complexes. [ABSTRACT FROM AUTHOR]

Altering the donor properties of phosphane ligands through substituent variation is an established tool in coordination chemistry and catalysis. This contribution describes the synthesis of two new hybrid donors (L) combining 1,3,5,7‐tetramethyl‐2,4,6‐trioxa‐8‐phosphaadamantane‐8‐yl (PCg) and nitrile donor groups at different molecular scaffolds, viz. ferrocene‐1,1′‐diyl (fc) and 1,2‐phenylene. These ligands were used to prepare dimeric Au(I) complexes [Au2(μ(P,N)‐L)2][SbF6]2, which were evaluated as silver‐free, preformed catalysts in Au‐mediated cycloisomerization of (Z)‐3‐methylpent‐2‐en‐4‐yn‐1‐ol to 2,3‐dimethylfuran. The catalyst featuring the ferrocene‐based ligand, viz. [Au2(μ(P,N)‐CgPfcCN)2][SbF6]2, showed the best catalytic performance at low catalyst loading (0.5 or 0.15 mol.%), which exceeded that of its diphenylphosphanyl analog [Au2(μ(P,N)‐Ph2PfcCN)2][SbF6]2 studied earlier and the prototypical Au(I) precatalyst [Au(PPh3)(MeCN)][SbF6]. [ABSTRACT FROM AUTHOR]

Gold(I) metal complexes are finding increasing applications as therapeutic agents against a variety of diseases. As their potential use as effective metallodrugs is continuously confirmed, the issue of their administration, distribution and delivery to desired biological targets emerges. Graphene and its derivatives possess attractive properties in terms of high affinity and low toxicity, suggesting that they can efficaciously be used as drug nanocarriers. In the present study, we computationally address the adsorption of a gold(I) N-heterocyclic monocarbene, namely, IMeAuCl (where IMe = 1,3-dimethylimidazol-2-ylidene), on graphene. The Au(I) N-heterocyclic carbene family has indeed shown promising anticancer activity and the N-heterocyclic ring could easily interact with planar graphene nanostructures. By means of high-level electronic structure approaches, we investigated the strength and nature of the involved interaction using small graphene prototypes, which allow us to benchmark the best-performing DFT functionals as well as assess the role of the different contributions to total interaction energies. Moreover, realistic adsorption enthalpies and free energy values are obtained by exploiting the optimal DFT method to describe the drug adsorption on larger graphene models. Such values (ΔHads = −18.4 kcal/mol and ΔGads= −7.20 kcal/mol for the largest C150H30 model) indicate a very favorable adsorption, mainly arising from the dispersion component of the interaction, with the electrostatic attraction also playing a non-negligible role. [ABSTRACT FROM AUTHOR]

Owing of their accessibility and wide range of reactivities, alkynes make for fascinating building blocks. Either a selective alkyne carbon-carbon triple bond reaction or activation of the terminal alkyne C-H bond may be employed to functionalize them. Monocationic coinage metal complexes with a d10 electronic configuration are effective catalysts for alkyne activation. Silver(I) and gold(I) N-heterocyclic (NHC) systems are emerging as promising catalysts in multicomponent alkyne activation reactions; this review paper focuses on A3 (aldehyde-amine-alkyne)-coupling reaction and carbon dioxide fixation, furnishing a systematic overview of the scientific advances achieved during the last two decades. This study will carefully compare the corresponding silver and gold complexes employed in the two processes. The differences in reaction routes brought about by the catalyst ligand structure will be investigated with an emphasis on evaluating the benefits provided by the easily tuneable NHC backbone, in terms of chemo- and stereo-selectivity. [ABSTRACT FROM AUTHOR]

N-Heterocyclic carbenes (NHCs) are nowadays one of the most widely employed ligands in organometallic chemistry and homogeneous catalysis due to the inherent stability of the metal-carbene bond and the ease of modification of the backbone as well as the N-wingtips substituents of these ligands. The functionalization of NHCs with hydrophilic groups offers the possibility of using NHC-metal complexes in aqueous catalysis, a hot topic within the Green Chemistry context due to the positive implications associated with the use of water as a reaction medium. In line with the enormous interest aroused by gold complexes in catalysis, significant efforts have been directed in the last years to the design and application of hydrophilic NHC-gold catalysts. This review is aimed to summarize the research in this area. The catalytic applications of water-soluble gold nanoparticles stabilized by hydrophilic NHCs are also covered. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) is currently regarded as a promising method for the treatment of oncological diseases. However, it involves a number of limitations related to the specific features of the method and the specific characteristics of photosensitizer molecules, including tumor hypoxia, small depth of light penetration into the tumor tissue, and low accumulation sensitivity. These drawbacks can be overcome by combining PDT with other treatment methods, for example, chemotherapy. In this work, we were the first to obtain agents that contain bacteriopurpurinimide as a photodynamic subunit and complexes of gold(I) that implement the chemotherapy effect. To bind the latter agents, N-heterocyclic carbenes (NHC) based on histidine and histamine were obtained. We considered alternative techniques for synthesizing the target conjugates and selected an optimal one that enabled the production of preparative amounts for biological assays. In vitro studies showed that all the compounds obtained exhibited high photoinduced activity. The C-donor Au(I) complexes exhibited the maximum specific activity at longer incubation times compared to the other derivatives, both under exposure to light and without irradiation. In in vivo studies, the presence of histamine in the NHC-derivative of dipropoxy-BPI (7b) had no significant effect on its antitumor action, whereas the Au(I) metal complex of histamine NHC-derivative with BPI (8b) resulted in enhanced antitumor activity and in an increased number of remissions after photodynamic treatment. [ABSTRACT FROM AUTHOR]

In this contribution, we provide an overview of gold compound applications against viruses or parasites during recent years. The special properties of gold have been the subject of intense investigation in recent years, which has led to the development of its chemistry with the synthesis of new compounds and the study of its applicability in various areas such as catalysis, materials, nanotechnology and medicine. Herein, thirteen gold articles with applications in several viruses, such as hepatitis C virus (HCV), influenza A virus (H1N1), vesicular stomatitis virus (VSV), coronavirus (SARS-CoV and SARS-CoV-2), Dengue virus, and several parasites such as Plasmodium sp., Leishmania sp., Tripanossoma sp., Brugia sp., Schistosoma sp., Onchocerca sp., Acanthamoeba sp., and Trichomonas sp. are described. Gold compounds with anti-viral activity include gold nanoparticles with the ligands mercaptoundecanosulfonate, 1-octanethiol and aldoses and gold complexes with phosphine and carbene ligands. All of the gold compounds with anti-parasitic activity reported are gold complexes of the carbene type. Auranofin is a gold drug already used against rheumatoid arthritis, and it has also been tested against virus and parasites.

In this study, the ligands were optimized at the B3LYP/6-31G(d) level and the complexes were optimized at the B3LYP/LANL2DZ/6-31G(d) level. Spectroscopic properties (IR, 1H NMR and 13C NMR) values ​​were taken from the calculation files. MOED was calculated using B3LYP/PBE0 methods. Egap values ​​were calculated and compared. Molecular docking study was applied to ligands and complexes and the results were interpreted. It was predicted that the ligands and complexes could be breast cancer drugs. [Display omitted] In this study, 1-(Acridin-9-yl)-3-methyl-benzimidazolium chloride (3a), 1-(Acridin-9-yl)-3-ethyl benzimidazolium bromide (3b), 1-(Acridin-9-yl)-3-benzyl benzimidazolium bromide (3c) and 1-(6-chloro-2-methoxyacridin-9-yl)-3-methyl benzimidazolium chloride (3d) ligands and Ag [1-(acridin-9-yl)- 3-methyl benzimidazolydiene] 2 (5a), Ag [1-(acridin-9-yl)-3-ethyl benzimidazolydiene] 2 (5b), Ag [1-(acridin-9-yl)-3-benzyl benzimidazolydiene] 2 (5c), Ag [1-(6-chloro-2-methoxy-acridin-9-yl)-3-methyl benzimidazolydiene] 2 (5d) complexes and hypothetical Au(I) complexes were analyzed by computational chemistry methods. The experimentally measured IR spectra of 3a, 3b, 3c, 3d ligands and their Ag(I) complexes were compared with the values calculated by the B3LYP, B3PW91, M062X methods. B3LYP/6-31G(d) for ligands and B3LYP/LANL2DZ/6-31G(d) for complexes were determined as the best computation level. By optimizing ligands and their Ag(I) and Au(I) type complexes in the gas phase, characterization calculations (IR and NMR spectra), electronic properties (MOED, HOMO and LUMO contour diagrams), some molecular properties (HOMO, LUMO, GAP, chemical hardness, chemical potential, ionization energy, electron affinity, electrophilicity index) were examined. Additionally, HOMO and LUMO energies were calculated with the PBE0 method. Energy gap values were calculated and proven by comparing with the B3LYP method.Using the Hex 8.0 docking program, the binding energies of the molecules against the breast cancer cell line (MCF7 (PDB: 3VHE)) were calculated. They were docked against the breast cancer cell line (MCF7 (PDB: 3VHE)) to predict their anticancer activities. By examining the binding energies of ligand and complexes, it was estimated that the anticancer activity of Au(I) complexes was higher. [ABSTRACT FROM AUTHOR]

The worldwide increase in antibiotic resistance poses a significant challenge, and researchers are diligently seeking new drugs to combat infections and prevent bacterial pathogens from developing resistance. Gold (I and III) complexes are suitable for this purpose. In this study, we tested four gold (I and III) complexes, (1) chlorotrimethylphosphine gold(I); (2) chlorotriphenylphosphine gold(I); (3) dichloro(2-pyridinecarboxylate) gold (III); and (4) 1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene gold(I) chloride, for their antibacterial, antibiofilm, antiviral, and anti-quorum sensing activities. Results reveal that 1 significantly inhibits Escherichia coli DSM 1077 and Staphylococcus aureus ATCC 6538, while 2, 3, and 4 only inhibit S. aureus ATCC 6538. The minimum inhibitory concentration (MIC) of 1 for S. aureus ATCC 6538 is 0.59 μg/mL (1.91 μM), and for methicillin-resistant S. aureus strains MRSA 12 and MRSA 15, it is 1.16 μg/mL (3.75 μM). For E. coli DSM 1077 (Gram-negative), the MIC is 4.63 μg/mL (15 μM), and for multi-resistant E. coli I731940778-1, it is 9.25 μg/mL (30 μM). Complex 1 also disrupts biofilm formation in E. coli and S. aureus after 6 h or 24 h exposure. Moreover, 1 and 2 inhibit the replication of two enterobacteria phages. Anti-quorum sensing potential still requires further clarification. These findings highlight the potential of gold complexes as effective agents to combat bacterial and viral infections.

Achieving large external quantum efficiencies, narrow bandwidths, and a long operational lifetime at high brightness remains the largest hurdle to developing organic blue‐emitting devices. Here, a material strategy is demonstrated that can meet these conditions. The strategy is based on linear heteroleptic Au(I) complex exciton harvesters and multiresonance thermally activated delayed fluorescence (MR‐TADF) emitters. The organic electroluminescence devices produce blue emission with Commission Internationale de l'Eclairage chromaticity coordinates of (0.108, 0.160), a narrow full‐width at half‐maximum value of 20 nm, and a maximum external quantum efficiency (EQE) as high as 30.2%. Notably, the EQE value remains 22.2% at 2000 cd m−2, whereas conventional control devices with an organic exciton harvester suffer from huge roll‐offs in quantum efficiency. An additional benefit of the device is a one‐order‐of‐magnitude improvement in its operational lifetime compared with that of the control device. Finally, the investigations reveal that the improvements are attributable to the unique ability of the Au(I) complexes for ultrafast triplet exciton harvest. In addition, the Au(I) complexes can facilitate Förster energy transfer to the MR‐TADF emitter, with effective suppression of hazardous triplet–triplet Dexter energy transfer. It is believed that the research is helpful in commercializing high‐efficiency and stable blue electroluminescence devices. [ABSTRACT FROM AUTHOR]

In this paper we describe the synthesis of new N-heterocyclic carbene (NHC) gold(I) derivatives with flavone-derived ligands with a propargyl ether group. The compounds were screened for their antimicrobial and anticancer activities, showing greater activity against bacteria than against colon cancer cells (Caco-2). Complexes [Au(L2b)(IMe)] (1b) and [Au(L2b)(IPr)] (2b) were found to be active against both Gram-positive and Gram-negative strains. The mechanism of action of 1b was evaluated by measurement of thioredoxin reductase (TrxR) and dihydrofolate reductase (DHFR) activity, besides scanning electron microscopy (SEM). Inhibition of the enzyme thioredoxin reductase is not observed in either Escherichia Coli or Caco-2 cells; however, DHFR activity is compromised after incubation of E. coli cells with complex 1b. Moreover, loss of structural integrity and change in bacterial shape is observed in the images obtained from scanning electron microscopy (SEM) after treatment E. coli cells with complex 1b. [ABSTRACT FROM AUTHOR]

This work focuses on the photocatalytic production of hydrogen from the photodehydrogenation of ethanol using several gold(I) complexes and gold(0) systems over titanium dioxide (P90 TiO 2 ) as hybrid photocatalysts. The photocatalytic systems are composed of at least one coumarin-based ligand, which can enhance the photocatalytic activity by its photon-absorbing capacity due to its chromophore properties. The photocatalytic behavior for hydrogen generation of the studied samples is compared under UV-vis light setting the total gold-based co-catalyst loading at 1 wt% onto the TiO 2 photocatalysts and when the gold content is maintained at 0.25 wt%. The incorporation of gold co-catalysts results in an enhancement of hydrogen production up to 2.7 times compared to a conventional Au/TiO 2 reference sample. The results show an increase in the total hydrogen production under UV-vis light due to the combined presence of coumarin chromophore, gold-based co-catalysts, and gold plasmonic nanoparticles. A deep characterization of the samples from each group is performed by UV-vis spectroscopy, XPS, HRTEM, and HAADF-STEM, observing the presence of plasmonic gold nanoparticles for sample "AuL1NPs" and the reduction of the gold present in sample "AuL1a," which explains the highest observed hydrogen production rates of this study., (© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)

The antitumor activity of various gold compounds is a promising field of investigation, attracting researchers seeking potential clinical candidates. To advance this research, they explore the complex mechanisms of action of these compounds. Since the discovery of the strong inhibition of thioredoxin reductase by auranofin, the primary mechanism explored has been the inhibition of this enzyme. This inhibition disrupts the redox balance in cells, promoting oxidative stress and triggering cell death. In this review, we analyzed studies from the past decade that measured cellular ROS increase and examined the coordination structures of gold compounds. We also correlate ROS increase with the inhibition of redox-regulating enzymes, thioredoxin reductase, and glutathione reductase, to elucidate the relationship between these cellular effects and chemical structures. Our data compilation reveals that different structures exhibit varying efficacy: some significantly increase ROS production and inhibit thioredoxin reductase or glutathione reductase, while others elevate ROS levels without affecting these target enzymes, suggesting alternative mechanisms of action. This review consolidates critical evidence, enhancing our understanding of the mechanisms by which these gold complexes act and providing valuable insights for developing new therapeutic strategies against tumor cells., (© 2024 Wiley-VCH GmbH.)

Cancer is widely recognized as a serious disease that poses a significant threat to human life and health. The distinctive chemical properties and pronounced antiproliferative activity of platinum drugs are considered to be responsible for their remarkable efficacy in clinical applications. However, undesirable side effects and resistance have severely hampered the treatment of various types of cancer with platinum-based drugs. Natural products (NPs) exhibit extensive pharmacological activities and represent an important source for developing cancer therapeutics. Therefore, the combination of metals and NPs is an attractive strategy for the development of new anticancer agents. Several studies have indicated that combining metals with NPs has a synergistic enhancement effect in antitumor activity. For transition metals, there has been burgeoning research output investigating NP-conjugated platinum and gold complexes. The present article reviews the progress made over the past 5-10 years on the development of NP-conjugated platinum and gold complexes, including a brief introduction to their chemistry and mechanism of action, and a summary of their benefits., Competing Interests: Declaration of competing interest The authors declare no competing financial interest., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Until the year 2000, gold compounds were considered catalytically inert. Subsequently, it was found that they are able to promote the nucleophilic attack on unsaturated substrates by forming an Au–π-system. The main limitation in the use of these catalytic systems is the ease with which they decompose, which is avoided by stabilization with an ancillary ligand. N-heterocyclic carbenes (NHCs), having interesting σ-donor capacities, are able to stabilize the gold complexes (Au (I/III) NHC), favoring the exploration of their catalytic activity. This review reports the state of the art (years 2007–2022) in the nucleophilic addition of amines (hydroamination) and water (hydration) to the terminal and internal alkynes catalyzed by N-heterocyclic carbene gold (I/III) complexes. These reactions are particularly interesting both because they are environmentally sustainable and because they lead to the production of important intermediates in the chemical and pharmaceutical industry. In fact, they have an atom economy of 100%, and lead to the formation of imines and enamines, as well as the formation of ketones and enols, all important scaffolds in the synthesis of bioactive molecules, drugs, heterocycles, polymers, and bulk and fine chemicals. [ABSTRACT FROM AUTHOR]

The use of alkynyl gold(I) complexes covers different research fields, such as bioinorganic chemistry, catalysis, and material science, considering the luminescent properties of the complexes. Regarding this last application, we report here the synthesis of three novel dinuclear gold(I) complexes of the general formula [(diNHC)(Au-C≡CPh)2]: two Au-C≡CPh units are connected by a bridging di(N-heterocyclic carbene) ligand, which should favor the establishment of semi-supported aurophilic interactions. The complexes can be easily synthesized through mechanochemistry upon reacting the pristine dibromido complexes [(diNHC)(AuBr)2] with phenylacetylene and KOH. Interestingly, we were also able to isolate the monosubstituted complex [(diNHC)(Au-C≡CPh)(AuBr)]. The gold(I) species were fully characterized by multinuclear NMR spectroscopy and mass spectrometry. The emission properties were also evaluated, and the salient data are comparable to those of analogous compounds reported in the literature. [ABSTRACT FROM AUTHOR]

The photophysical properties of two classes of porphyrins and metalloporphyrins linked to N-heterocyclic carbene (NHC) Au(I) complexes have been investigated by means of density functional theory and its time-dependent extension for their potential application in photodynamic therapy. For this purpose, the absorption spectra, the singlet–triplet energy gaps, and the spin–orbit coupling (SOC) constants have been determined. The obtained results show that all the studied compounds possess the appropriate properties to generate cytotoxic singlet molecular oxygen, and consequently, they can be employed as photosensitizers in photodynamic therapy. Nevertheless, on the basis of the computed SOCs and the analysis of the metal contribution to the involved molecular orbitals, a different influence in terms of the heavy atom effect in promoting the intersystem crossing process has been found as a function of the identity of the metal center and its position in the center of the porphyrin core or linked to the peripheral NHC. [ABSTRACT FROM AUTHOR]

• Auranofin has significant antibacterial activity against Gram-positive bacteria. • Auranofin is very effective to multidrug-resistant Gram-positive bacteria. • Cross-resistance was not found in the existing antibiotics in combination with auranofin. • The structural modification of auranofin can improve the antibacterial activity against Gram-negative bacteria. Multidrug resistance (MDR) is a significant issue associated with the clinical application of antibiotics. It is also challenging to discover and develop new antibiotics with novel scaffolds. Therefore, the repurposing of existing drugs has become a promising strategy for antibiotic drug discovery. Auranofin, an approved gold metallic drug, has been used for the treatment of rheumatoid arthritis (RA) for many years. Recent research revealed that auranofin has strong antibacterial activity against multiple Gram-positive bacteria by inhibiting thioredoxin reductase (TrxR). These results inspired the development of gold complexes as antibacterial agents. Herein, we discuss recent advances in the development of auranofin and other gold complexes as antibacterial agents, providing a new viewpoint for the treatment of bacterial infection. [ABSTRACT FROM AUTHOR]

The crystal structure of the human telomeric DNA Tel24 G-quadruplex (Tel24 = TAG 3 (T 2 AG 3) 3 T) in complex with the novel [AuL] species (with L = 2,4,6-tris(2-pyrimidyl)-1,3,5-triazine - TPymT-α) was solved by a novel joint molecular mechanical (MM)/quantum mechanical (QM) innovative approach. The quantum-refinement crystallographic method (crystallographic refinement enhanced with quantum mechanical calculation) was adapted to treat the [AuL]/G-quadruplex structure, where each gold complex in the binding site was found spread over four equally occupied positions. The four positions were first determined by docking restrained to the crystallographically determined metal ions' coordinates. Then, the quantum refinement method was used to resolve the poorly defined density around the ligands and improve the crystallographic determination, revealing that the binding preferences of this metallodrug toward Tel24 G-quadruplex arise from a combined effect of pyrimidine stacking, metal–guanine interactions and charge–charge neutralizing action of the π-acid triazine. The occurrence of interaction in solution with the Tel24 G-quadruplex DNA was further proved through DNA melting experiments, which showed a slight destabilisation of the quadruplex upon adduct formation. [Display omitted] • G4 can be characterized by non-unique positioning of ligands on the guanine tetrad. • Crystallographic refinement enhanced with QM/MM calculations • Mononuclear gold complex stacked at the 3′-end G-tetrad of the human telomeric DNA [ABSTRACT FROM AUTHOR]

Brain cancer, one of the most lethal diseases, urgently requires the discovery of novel theranostic agents. In this context, molecules based on six‐membered phosphorus heterocycles – phosphaphenalenes – are especially attractive; they possess unique characteristics that allow precise chemical engineering. Herein, we demonstrate that subtle structural modifications of the phosphaphenalene‐based gold(I) complexes lead to modify their electronic distribution, endow them with marked photophysical properties and enhance their efficacy against cancer. In particular, phosphaphenalene‐based gold(I) complexes containing a pyrrole ring show antiproliferative properties in 14 cell lines including glioblastomas, brain metastases, meningiomas, IDH‐mutant gliomas and head and neck cancers, reaching IC50 values as low as 0.73 μM. The bioactivity of this new family of drugs in combination with their photophysical properties thus offer new research possibilities for both the fundamental investigation and treatment of brain cancer. [ABSTRACT FROM AUTHOR]

In this contribution, we provide an overview of gold compound applications against viruses or parasites during recent years. The special properties of gold have been the subject of intense investigation in recent years, which has led to the development of its chemistry with the synthesis of new compounds and the study of its applicability in various areas such as catalysis, materials, nanotechnology and medicine. Herein, thirteen gold articles with applications in several viruses, such as hepatitis C virus (HCV), influenza A virus (H1N1), vesicular stomatitis virus (VSV), coronavirus (SARS-CoV and SARS-CoV-2), Dengue virus, and several parasites such as Plasmodium sp., Leishmania sp., Tripanossoma sp., Brugia sp., Schistosoma sp., Onchocerca sp., Acanthamoeba sp., and Trichomonas sp. are described. Gold compounds with anti-viral activity include gold nanoparticles with the ligands mercaptoundecanosulfonate, 1-octanethiol and aldoses and gold complexes with phosphine and carbene ligands. All of the gold compounds with anti-parasitic activity reported are gold complexes of the carbene type. Auranofin is a gold drug already used against rheumatoid arthritis, and it has also been tested against virus and parasites. [ABSTRACT FROM AUTHOR]

Since their first discovery, N-heterocyclic carbenes have had a significant impact on organometallic chemistry. Due to their nature as strong σ-donor and π-acceptor ligands, they are exceptionally well suited to stabilize Au(I) and Au(III) complexes in biological environments. Over the last decade, the development of rationally designed NHCAu(I/III) complexes to specifically target DNA has led to a new "gold rush" in bioinorganic chemistry. This review aims to summarize the latest advances of NHCAu(I/III) complexes that are able to interact with DNA. Furthermore, the latest advancements on acyclic diamino carbene gold complexes with anticancer activity are presented as these typically overlooked NHC alternatives offer great additional design possibilities in the toolbox of carbene-stabilized gold complexes for targeted therapy. [ABSTRACT FROM AUTHOR]

In the present work the reaction of hydrazone ligand with AuCl3 was investigated. The ligand that could be obtained by the condensation of thiosemicarbazide with p-diaminobenzaldehyde belong to the class of mononegative or binegative bidentate ligands. The structure of the prepared samples has been defined by infrared spectroscopy, elemental analyzes, ¹H-13C NMR, SEM, and Powder XRD techniques. The ligand is present in both solid and liquid states in the thione form. The ligand is binding to Au via, azomethine nitrogen and thione sulfur atoms. Powder XRD pattern of ligand and [AuHLCl2]Cl complex show several diffraction peaks with high intensity indicating the crystalline nature of them. The observation of new diffraction peaks at different positions indicates the successful formation of the complex. The synthesized ligand and complex have crystallites sizes of 103 and 46 nm, respectively indicating the nanostructure of them. The ligand and it complex shows different particles shapes of plates, sheets, and spheres. Optimizations of the geometries of the formed complex with gold and the ligand were carried out by using DFT in a gaseous state. The excited states of various multiplicities were examined by the TD-DFT. [ABSTRACT FROM AUTHOR]

Porphyrins bearing imidazolium salts were synthesized and used as N-heterocylic carbene (NHC) precursors for the preparation of gold(I) complexes. The dark toxicity and phototoxicity of the obtained compounds were investigated in vitro on MCF-7 breast cancer cells. The obtained data showed that porphyrins equipped with imidazolium salts are non-toxic in the dark and present interesting photodynamic properties. On the contrary, corresponding NHC-gold(I) complexes are not suitable photosensitizers for photodynamic therapy (PDT) applications. Their dark toxicity strongly depends on the nature of the linker between the porphyrin core and the NHC. This work was extended to the synthesis of a pyropheophorbide a derivative with a pendant imidazolium group for PDT applications using excitation wavelengths of 450 nm, 545 nm, and importantly of 650 nm.

The ability of gold-based complexes in diagnosis and treatment of cancers as the main worldwide health problems, along with the successful clinical reports of bioactive azole-based drugs has attracted high attention from medicinal chemists and increased the significant interest in conducting research of azole-based gold complexes. The present review gives an updated overview of the anticancer potential of nitrogen-rich azole-based gold coordination complexes with the aim of providing an insight into the correlations between the biological activity and chemical structures of these complexes to the achievement of efficient anticancer agents. Comparison of the anticancer potential of these complexes clearly indicates the role of various influencing factors in this case. Selection and designing of suitable ligands and analysis of the structure-activity relationships (SAR) of compounds is the true cornerstone and a key constituent in medicinal chemistry. The geometry of complexes, the oxidation states of the gold centers along with the effect of the donor atoms, the types of ligands and the existence of different groups in the framework of the ligands are the important parameters that determine the final bioactivity of the complexes. The synergic mechanism of action along with combination therapies of them are another approach that can overcome the limitations of some of the approved drugs. These complexes can be efficient in cancer therapy as chemotherapy agents, as photodynamic therapy (PDT) agents and as biomolecule imaging agents. We believe that this review can prompt widespread studies and progress in order to design and synthesize efficient complexes in treatment and diagnosis of cancer. Finding and concluding the molecular mechanism of action and the synergic pathway of the complexes and comparison of the corresponding data can help to the development of efficient anticancer drugs with low toxicity and least side effects with respect to the combination therapy and considering the synergic mechanism of action of them. This review will be interesting for inorganic chemists and specialists in medicinal chemistry about the discovery and development of anticancer drugs. [Display omitted] • The future perspectives of gold-based complexes as anticancer agents are outlined. • The framework of complexes and oxidation states of gold affect anticancer activity. • The majority of reported gold complexes reveal synergic mechanisms of action. • The mechanism of action of complexes was surveyed. • The majority of gold complexes revealed higher activity than corresponding ligands. [ABSTRACT FROM AUTHOR]

Gold(I) metal complexes are finding increasing applications as therapeutic agents against a variety of diseases. As their potential use as effective metallodrugs is continuously confirmed, the issue of their administration, distribution and delivery to desired biological targets emerges. Graphene and its derivatives possess attractive properties in terms of high affinity and low toxicity, suggesting that they can efficaciously be used as drug nanocarriers. In the present study, we computationally address the adsorption of a gold(I) N-heterocyclic monocarbene, namely, IMeAuCl (where IMe = 1,3-dimethylimidazol-2-ylidene), on graphene. The Au(I) N-heterocyclic carbene family has indeed shown promising anticancer activity and the N-heterocyclic ring could easily interact with planar graphene nanostructures. By means of high-level electronic structure approaches, we investigated the strength and nature of the involved interaction using small graphene prototypes, which allow us to benchmark the best-performing DFT functionals as well as assess the role of the different contributions to total interaction energies. Moreover, realistic adsorption enthalpies and free energy values are obtained by exploiting the optimal DFT method to describe the drug adsorption on larger graphene models. Such values (ΔHads = −18.4 kcal/mol and ΔGads= −7.20 kcal/mol for the largest C150H30 model) indicate a very favorable adsorption, mainly arising from the dispersion component of the interaction, with the electrostatic attraction also playing a non-negligible role.

• Biphenyl-NHC-gold(I) complexes were synthesized and characterized. • Complex Au-1 displayed strong antiproliferative activity against human ovarian cancer cells. • Complex Au-1 exhibited low toxicity to normal ovarian epithelial IOSE-80 cells. • Complex Au-1 exhibited significant inhibition of TrxR. Fifteen novel biphenyl- N -heterocyclic carbene (NHC)-gold(I) complexes were designed and synthesized to treat ovarian cancer (OC). Among these, complex Au-1 showed significant antiproliferative activity against A2780 cells and A2780/CDDP cells. Notably, Au-1 exhibited low toxicity to normal ovarian epithelial IOSE-80 cells. Further studies revealed that Au-1 strongly inhibited thioredoxin reductase (TrxR) activity. Collectively, our results demonstrated that Au-1 could be a promising candidate for the treatment of OC. We synthesized a halo-biphenyl-NHC-gold(I) complex Au-1 , which displayed significant antiproliferative activity against ovarian cancer cells and low toxicity to normal ovarian epithelial cells. [Display omitted] [ABSTRACT FROM AUTHOR]

Owing of their accessibility and wide range of reactivities, alkynes make for fascinating building blocks. Either a selective alkyne carbon-carbon triple bond reaction or activation of the terminal alkyne C-H bond may be employed to functionalize them. Monocationic coinage metal complexes with a d10 electronic configuration are effective catalysts for alkyne activation. Silver(I) and gold(I) N-heterocyclic (NHC) systems are emerging as promising catalysts in multicomponent alkyne activation reactions; this review paper focuses on A3 (aldehyde-amine-alkyne)-coupling reaction and carbon dioxide fixation, furnishing a systematic overview of the scientific advances achieved during the last two decades. This study will carefully compare the corresponding silver and gold complexes employed in the two processes. The differences in reaction routes brought about by the catalyst ligand structure will be investigated with an emphasis on evaluating the benefits provided by the easily tuneable NHC backbone, in terms of chemo- and stereo-selectivity.

Three gold(III) complexes were synthesized using 2-pyrazinecarboxamide, pyridine or bipyridine ligand. Complexes were characterized by spectroscopic and analytical techniques (IR, Raman, 1H NMR, mass spectrometry and elemental analysis). Thermogravimetry and conductivity of complexes were investigated. IR, Raman and theoretical calculations of spectral modes of vibrations using DFT and MP2 methods were performed. Biological activities of the complexes against two bacteria Escherichia coli and Staphylococcus aureus and two fungi Aspergillus flavus and Candida albicans were screened. They exhibited activities toward both bacteria and fungi. Potency assays of the complexes against two breast cancer and liver carcinoma cell lines were evaluated. They exhibited in vitro activities toward the tumors relative to cis-platin. In addition, fluorescence quenching studies viscosity measurements of the complexes are performed. Theoretical calculations based on accurate DFT were established to verify the optimized structures of complexes. Global chemical reactivity descriptors were estimated from energy of HOMO and LUMO orbitals. [ABSTRACT FROM AUTHOR]

In this work, the spectrophotometric studies on the kinetics of redox reaction between gold(III) bromide complexes and sodium nitrite, were carried out. From the kinetic curves collected under different conditions of reactants concentration, addition of bromide ions, temperature, pH and ionic strength, corresponding rate constants have been determined. The obtained results suggest the complex path of the [AuBr4]– reduction consisting of two parallel, bimolecular reactions where different reductant species (HNO2 and NO2–) take place and consecutive step with the metallic gold production. The second-order rate constants at 20oC are equal to 2.948 and 0.191 M–1·s–1, respectively. The values of activation enthalpy and activation entropy for the first and the second parallel step of the reaction were found to be ΔH‡ = 29.18 kJ·mol–1 and ΔS‡ = –13.95 J·mol–1·K, and ΔH‡ = 40.75 kJ·mol–1 and ΔS‡ = –31.06 ­J·mol–1·K, respectively. It was found that the reaction accelerates significantly with the increase of pH and is inhibited with the increase of Br– concentration. The substitutive, inner-sphere mechanism of electron transfer in the studied system was also suggested.

N-Heterocyclic carbenes (NHCs) are nowadays one of the most widely employed ligands in organometallic chemistry and homogeneous catalysis due to the inherent stability of the metal-carbene bond and the ease of modification of the backbone as well as the N-wingtips substituents of these ligands. The functionalization of NHCs with hydrophilic groups offers the possibility of using NHC-metal complexes in aqueous catalysis, a hot topic within the Green Chemistry context due to the positive implications associated with the use of water as a reaction medium. In line with the enormous interest aroused by gold complexes in catalysis, significant efforts have been directed in the last years to the design and application of hydrophilic NHC-gold catalysts. This review is aimed to summarize the research in this area. The catalytic applications of water-soluble gold nanoparticles stabilized by hydrophilic NHCs are also covered.

Photodynamic therapy (PDT) is currently regarded as a promising method for the treatment of oncological diseases. However, it involves a number of limitations related to the specific features of the method and the specific characteristics of photosensitizer molecules, including tumor hypoxia, small depth of light penetration into the tumor tissue, and low accumulation sensitivity. These drawbacks can be overcome by combining PDT with other treatment methods, for example, chemotherapy. In this work, we were the first to obtain agents that contain bacteriopurpurinimide as a photodynamic subunit and complexes of gold(I) that implement the chemotherapy effect. To bind the latter agents, N-heterocyclic carbenes (NHC) based on histidine and histamine were obtained. We considered alternative techniques for synthesizing the target conjugates and selected an optimal one that enabled the production of preparative amounts for biological assays. In vitro studies showed that all the compounds obtained exhibited high photoinduced activity. The C-donor Au(I) complexes exhibited the maximum specific activity at longer incubation times compared to the other derivatives, both under exposure to light and without irradiation. In in vivo studies, the presence of histamine in the NHC-derivative of dipropoxy-BPI (7b) had no significant effect on its antitumor action, whereas the Au(I) metal complex of histamine NHC-derivative with BPI (8b) resulted in enhanced antitumor activity and in an increased number of remissions after photodynamic treatment.

A series of gold(I) and gold(III) complexes with N‐heterocyclic carbene ligands functionalized with a pendant thioether group (NHC‐SR) was synthesized with straightforward procedures and characterized in solution with NMR spectroscopy and ESI‐MS spectrometry, as well as in the solid state by means of single crystal X‐ray diffraction analysis. Selected experimental aspects were rationalized through relativistic DFT calculations. The gold(I) and gold(III) complexes displayed moderate in vitro cytotoxicity towards breast cancer cells MCF7. [ABSTRACT FROM AUTHOR]

In this work, we show that intramolecular hydrogen bonding can be used to stabilize tri-coordinated phosphane-gold(I) complexes. Two molecular structures of 2-(diphenylphosphino)benzoic acid (L) coordinated to a gold(I) atom were determined by single-crystal X-ray diffraction. The linear L–Au–Br shows a standard linear coordination and dimerizes via hydrogen bonds of the carboxylic acid. Upon addition of two additional phosphane ligands the complex [L3Au]X is formed which is stabilized by three intramolecular –C(O)O–H...X hydrogen bonds as proven by the X-ray structure of the respective chlorido-complex. X-ray powder diffractograms suggest the same structure also for X– = Br– and I–. [ABSTRACT FROM AUTHOR]

Luminescence from a gold(I) complex with an N‐heterocycliccarbene‐based ligand, 1+⋅NTf2−, increased rapidly upon the application of one‐shot needlestick‐stimulus. The weakly orange‐emitting solid‐state of 1+⋅NTf2− was prepared by cooling its melted liquid to 90 °C. Upon applying a weak pinpoint stimulus with a needle, this weakly orange‐emitting solid state transformed into an intensively violet‐blue‐emitting state on a timescale of seconds. The emission after applying the stimulus could be visualized upon UV excitation even under ambient room light. This sequential phase transition from a stable solid to a liquid and then to a metastable solid could occur repeatedly without any measurable degradation of the complex. Various shapes could be prepared by casting the liquid‐state complex into molds of different designs. This rapid response is thought to be triggered by the flexible intermolecular interactions in the kinetically generated aggregates formed upon cooling the liquid state, and by the strong Au–Au interactions in the thermodynamically stable crystals after applying the needlestick‐stimulus. [ABSTRACT FROM AUTHOR]