Heterometallic Au(I)-Cu(I) Clusters: Luminescence Studies and 1O2 Production

Two different organometallic gold(I) compounds containing naphthalene and phenanthrene as fluorophores and 2-pyridyldiphenylphosphane as the ancillary ligand were synthesized (compounds 1 with naphthalene and 2 with phenanthrene). They were reacted with three different copper(I) salts with different counterions (PF₆^-, OTf^-, and BF₄^-; OTf = triflate) to obtain six Au(I)/Cu(I) heterometallic clusters (compounds 1a-c for naphthalene derivatives and 2a-c for phenanthrene derivatives). The heterometallic compounds present red pure room-temperature phosphorescence in both solution, the solid state, and air-equilibrated samples, as a difference with the dual emission recorded for the gold(I) precursors 1 and 2. The presence of Au(I)-Cu(I) metallophilic contacts has been identified using single-crystal X-ray diffraction structure resolution of two of the compounds, which play a direct role in the resulting red-shifted emission with respect to the gold(I) homometallic precursors. Polystyrene (PS) and poly(methyl methacrylate) (PMMA) polymeric matrices were doped with our luminescent compounds, and the resulting changes in their emissive properties were analyzed and compared with those previously recorded in the solution and the solid state. All complexes were tested to analyze their ability to produce ¹O₂ and present very good values of Φ_Δ up to 50%.

Mono- and Dinuclear Gold(I) Coumarin Complexes: Luminescence Studies and Singlet Oxygen Production

The 4-(thiolmethyl)-7-(diethylamino)-2H-chromen-2-one ligand has been synthesized and used as chromophore in several mono- and dinuclear gold(I) compounds that contain a phosphane at the second coordination position. Four final products were able to obtain in pure form containing one coumarin and one phosphane ligand in the case of PTA (1,3,5-triaza-7-phosphatricyclo[3.3.1.13.7]decane) and PPh₃ (triphenylphosphine); one coumarin and two gold(I)-phosphane groups in the case of phosphane=DAPTA (3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane) and two coumarin and two gold(I) atoms in the case of phosphane=DPEphos (bis[(2-diphenylphosphino)phenyl]ether), when it was used a diphosphane. Other diphosphane ligands used were not able to give the desired products in pure form. The luminescent properties of the compounds are governed by the fluorescence of the coumarin moiety in all compounds both for measurements carried out in solution and also immobilized in PMMA organic matrix. Phosphorescence emission can be detected in all cases at 77 K both for the uncoordinated coumarin ligand and the gold(I) derivatives, being more favoured in the presence of the gold(I) heavy atom. The compounds have been used as photosensitizers to generate ¹ O₂ with moderate quantum yields values.

Gold(i) complexes bearing a PNP-type pincer ligand: photophysical properties and catalytic investigations

The synthesis and characterization of two dinuclear and five tetranuclear gold(i) complexes bearing the 2,6-bis(diphenylphosphinomethyl)pyridine diphosphane ligand (DPPMPY) are herein reported.

Aggregation versus Biological Activity in Gold(I) Complexes. An Unexplored Concept

The aggregation process of a series of mono- and dinuclear gold(I) complexes containing a 4-ethynylaniline ligand and a phosphane at the second coordination position (PR3-Au-C≡CC6H4-NH2, complexes 1-5, and (diphos)(Au-C≡CC6H4-NH2)2, complexes 6-8), whose biological activity was previously studied by us, has been carefully analyzed through absorption, emission, and NMR spectroscopy, together with dynamic light scattering and small-angle X-ray scattering. These experiments allow us to retrieve information about how the compounds enter the cells. It was observed that all compounds present aggregation in fresh solutions, before biological treatment, and thus they must be entering the cells as aggregates. Inductively coupled plasma atomic emission spectrometry measurements showed that mononuclear complexes are mainly found in the cytosolic fraction; the dinuclear complexes are mainly found in a subsequent fraction composed of nuclei and cytoskeleton. Additionally, dinuclear complex 8 affects the actin aggregation to a larger extent, suggesting a cooperative effect of dinuclear compounds.

Comprehensive Investigation of the Photophysical Properties of Alkynylcoumarin Gold(I) Complexes

Six gold(I) complexes (R₃P-Au-Coum) containing three different alkynylcoumarin chromophores (Coum) with different electron-donating and electron-withdrawing characteristics and two different water-soluble phosphanes (PR₃ = PTA (a) and DAPTA (b)) have been synthesized (1a,b, unsubstituted coumarin; 2a,b, 4-methyl substituted coumarin; 3a,b, 3-chloro and 4-methyl substituted coumarin). A comprehensive study of the photophysical properties of the R₃P-Au-Coum, together with their propynyloxycoumarin precursors 1-3, was performed in solution at room and low temperatures. Spectral and photophysical characteristics of the R₃P-Au-Coum essentially depend on the electronic characteristics of the propynyloxycoumarin ligand. The presence of the Au(I) atom was found to be responsible for an increase of the intersystem crossing, with triplet state quantum yield values, ϕ_T, ranging from ∼0.05 to 0.35 and high coumarin phosphorescence quantum yield values for derivatives 1 and 2; fluorescence dominates the deactivation in derivatives 3. Efficient singlet oxygen photosensitization was observed for the new compounds 3a,b. From TDDFT calculations, the relevant HOMO and LUMO of the compounds, i.e., those involved in the transitions, are dominated by the frontier orbitals associated with the coumarin core. The Au(I)-phosphane structure introduces a new transition assigned to an intraligand transition involving the phosphane ligand, and π(C≡C) system, to the p orbitals of phosphorus and gold atoms.

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.

Gold(i)-doped films: new routes for efficient room temperature phosphorescent materials

The synthesis of four novel gold(i)-phosphane complexes coordinated to 9-phenanthrene chromophore has been carried out through the reaction of 9-phenanthreneboronic acid and the corresponding AuClPR₃ (PR₃ = PPh₃ for triphenylphosphane (1a); 1,4-bis(diphenylphosphanyl)butane or dppb (2b); bis(diphenylphosphanyl)acetylene or dppa (2c); (AuCl)₂(diphos) (diphos = bis(diphenylphosphanyl)methane or dppm (3)) sources. The X-ray crystal structures of compounds 1a and 2b show the existence of MOF-like intermolecular assemblies that contain empty inner cavities in the absence of aurophilic contacts. In contrast, the formation of a tetranuclear complex with intramolecular aurophilic interactions was evidenced for 3. Photophysical characterization indicates dual emission in all gold(i) complexes when oxygen is removed from the sample, while only fluorescence emission is recorded for the uncoordinated ligand. The introduction of the compounds within PMMA and Zeonex was assayed, and luminescent films containing gold(i) complexes where phosphorescence is the sole pathway for emission are obtained, instead of the dual emission (with significant fluorescence contribution) recorded in solution.

Fluorescent palladium(II) and platinum(II) NHC/1,2,3-triazole complexes: antiproliferative activity and selectivity against cancer cells

Fluorescent Pd(ii) and Pt(ii) complexes bearing 4-methylene-7-methoxycoumarin (MMC) and 2,6-diispropylphenyl (Dipp) substituted NHC/1,2,3-triazole hybrid ligands are described. Depending on the reaction conditions two different ligand coordination modes are observed, i.e., bidentate solely coordinating via NHCs or tetradentate coordinating via NHCs and 1,2,3-triazoles. All Dipp substituted complexes show antiproliferative activity against cervix (HeLa) and breast (MCF-7) human carcinoma cells. The activity significantly depends on the coordination mode, with the tetradentate motif being notably more effective (HeLa: IC50 = 3.9 μM to 4.7 μM; MCF-7: IC50 = 2.07 μM to 2.35 μM). Amongst the MMC series, only the Pd(ii) complex featuring the bidentate coordination mode is active against HeLa (IC50 = 6.1 μM). In contrast to its structurally related Dipp derivative (SI = 0.6), it shows a high selectivity for HeLa (SI > 16) compared to healthy skin cells (HaCaT). According to fluorescence microscopy, this compound is presumably located in late endosomes or lysosomes.

Effect of Gold(I) on the Room-Temperature Phosphorescence of Ethynylphenanthrene

The synthesis of two series of gold(I) complexes with the general formulae PR₃ -Au-C≡C-phenanthrene (PR₃ =PPh₃ (1 a/2 a), PMe₃ (1 b/2 b), PNaph₃ (1 c/2 c)) or (diphos)(Au-C≡C-phenanthrene)₂ (diphos=1,1-bis(diphenylphosphino)methane, dppm (1 d/2 d), 1,4-bis(diphenylphosphino)butane, dppb (1 e/2 e)) has been realized. The two series differ in the position of the alkynyl substituent on the phenanthrene chromophore, being at the 9-position (9-ethynylphenanthrene) for the L1 series and at the 2-position (2-ethynylphenanthrene) for the L2 series. The compounds have been fully characterized by ¹ H, ³¹ P NMR, and IR spectroscopy, mass spectrometry, and single-crystal X-ray diffraction resolution in the case of compounds 1 a, 1 e, 2 a, and 2 c. The emissive properties of the uncoordinated ligands and corresponding complexes have been studied in solution and within organic matrixes of different polarity (polymethylmethacrylate and Zeonex). Room-temperature phosphorescence (RTP) is observed for all gold(I) complexes whereas only fluorescence can be detected for the pure organic chromophore. In particular, the L2 series presents better luminescent properties regarding the intensity of emission, quantum yields, and RTP effect. Additionally, although the inclusion of all the compounds in organic matrixes induces an enhancement of the observed RTP owing to the decrease in non-radiative deactivation, only the L2 series completely suppresses the fluorescence, giving rise to pure phosphorescent materials.

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.

Facile morphology control of gold(0) structures from aurophilic assemblies

Different gold microstructures have been synthesized by using supramolecular gold(i) organometallic compounds as templates and Ag nanoparticles as reducing agents. The use of fibers resulting from supramolecular assemblies of neutral gold(i) compounds gives rise to the formation of microrods. The use of supramolecular assemblies from ionic molecules results in spherical or square-based prism gold microstructures, depending on the shape of the supramolecular gold(i) precursor assembly. In addition to temperature and reaction time, solvents exert a strong influence on the formation and morphology of gold structures, as borne out by the example that well-defined star-like morphologies have been obtained in chloroform.

Luminescent Tetranuclear Gold(I) Dibenzo[g,p]chrysene Derivatives: Effect of the Environment on Photophysical Properties

A new 2,7,10,15-tetraethynyldibenzo[g,p]chrysene ligand (1) and two tetranuclear gold(I) derivatives containing PPh₃ (3) and PMe₃ (4) phosphines were synthesized and characterized by ¹H and ³¹P NMR, IR spectroscopy, and high-resolution mass spectrometry. The compounds were studied in order to analyze the effect of the introduction of gold(I) on the supramolecular aggregation and photophysical properties. Absorption and emission spectra displayed broad bands due to the establishment of π π interactions as an indication of intermolecular contacts and the formation of aggregates. A decrease of the recorded quantum yield (QY) of the gold(I) derivatives was observed compared to the uncomplexed ligand. The introduction of the complexes into poly methyl methacrylate (PMMA) and Zeonex 480R matrixes was analyzed, and an increase of the measured QY of 4 in Zeonex was observed. No phosphorescent emission was detected.

An Application Exploiting Aurophilic Bonding and iClick to Produce White Light Emitting Materials

The paper focuses on exploiting aurophilic bonding to produce white light emitting materials. Inorganic Click (iClick) is employed to link two or four Au(I) metal ions through a triazolate bridge. Depending on the choice of phosphine ligand (PEt₃ or PPh₃), dinuclear Au₂-FO or tetranuclear Au₄-FO complexes can be controllably synthesized (FO = 2-(9,9-dioctylfluoreneyl-)). The iClick products Au₂-FO and Au₄-FO are characterized by combustion analysis and multinuclear NMR, TOCSY 1D, ¹H-¹³C gHMBC, and ¹H-¹³C gHSQC. In addition, the photophysical properties of Au₂-FO and Au₄-FO were examined in THF solution. Transient absorption spectroscopy was employed to elucidate the excited state features of the gold compounds. Solution processed OLEDs were fabricated and characterized, which gave white light electroluminescence with CIE coordinates (0.34, 0.36), as seen referenced to CIE standard illuminant D65 (0.31, 0.32). TDDFT computational analysis of Au₂-FO and Au₄-FO reveals the origin of light emission. In the case of Au₄-FO, direct excitation leads to increased aurophilic bonding in the excited state, and as a result the emission profile is broadened to cover a larger region of the visible spectrum, thus giving white light emission. Designing molecules that can access or increase aurophilic bonding in the excited state provides another tool for fine-tuning the emission profiles of gold complexes.

Aggregation induced emission of a new naphthyridine-ethynyl-gold(i) complex as a potential tool for sensing guanosine nucleotides in aqueous media

A new organometallic alkynyl-gold(i) complex capable of exhibiting aggregation induced emission was designed and synthesized. The linear complex structure possesses a central Au(i) atom, bearing two axial ligands: (1) 1,3,5-triaza-7-phosphaadamantane and (2) 2-acetamido-7-ethynyl-1,8-naphthyridine. While the former accounts for its partial solubility in an aqueous environment, the latter acts as a receptor unit for binding guanosine nucleotides and derivatives via multiple hydrogen bonding interactions. At high concentrations, aggregation of the complex was observed by the formation of new absorption (λ_max∼ 400 nm) and emission bands (550-700 nm). Formation of aggregates of ca. 60 nm diameter was confirmed by Small Angle X-ray Scattering (SAXS). Disruption of the aggregates in the presence of guanosine derivatives resulted in a ratiometric signal with apparent association constants in the order of 10⁵ M^-1 and high sensitivity (around 63% signal change) which are, to the best of our knowledge, in line with the highest values recorded for nucleotide sensors based on hydrogen bonding and capable of working in water. Computational studies indicate the presence of additional hydrogen bonding interactions that account for the strong binding of the Au(i) complex to phosphorylated guanosine nucleotides.

The Impact of Crystal Packing and Aurophilic Interactions on the Luminescence Properties in Polymorphs and Solvate of Aroylacetylide-Gold(I) Complexes

The influence of the chemical substitution, crystal packing, and aurophilic interactions of the gold(I) acetylide complexes of the type (ArCOC≡C)_n AuPEt₃ (n=1,2) on their luminescent properties were examined. All described complexes undergo ligand scrambling in solution, which results in the formation of stable, easily isolated crystals that contain [ArCO(C≡C)_n ]₂ Au^- (Et₃ P)₂ Au⁺ homoleptic species. In particular, we observed that the (benzoylacetylide)gold(I) complex yields three crystal forms with strikingly different luminescence properties. We monitored the conversion pathway for these forms: an orange luminescent form of homoleptic complex upon drying undergoes spontaneous transformation to bright green fluorescent form and finally to the weakly blue emissive one. In addition, we report a rare example of a helical arrangement of Au⋅Au⋅Au chains that are observed for the first time in acetylide gold(I) complexes in the case of heteroleptic (benzoylacetylide)gold(I) complex. This is a very rare case in which crystal structures and ensuing electronic properties of the heteroleptic and Au^I complexes could be directly compared.

Near-unity thermally activated delayed fluorescence efficiency in three- and four-coordinate Au(i) complexes with diphosphine ligands

The synthesis and photoluminescence properties of three-coordinate Au(i) complexes with rigid diphosphine ligands LMe {1,2-bis[bis(2-methylphenyl)phosphino]benzene}, LEt {1,2-bis[bis(2-ethylphenyl)phosphino]benzene}, and LiPr {1,2-bis[bis(2-isopropylphenyl)phosphino]benzene} are investigated. The LMe and LEt ligands afford two types of complexes: dinuclear complexes [μ-LMe(AuCl)2] (1d) and [μ-LEt(AuCl)2] (2d) with an Au(i)-Au(i) bond and mononuclear three-coordinate Au(i) complexes LMeAuCl (1) and LEtAuCl (2). On the other hand, the bulkiest ligand, LiPr, affords three-coordinate Au(i) complexes, LiPrAuCl (3) and LiPrAuI (4), but no dinuclear complexes. X-ray analysis suggests that both 3 and 4 possess a highly distorted trigonal planar geometry. Moreover, luminescence data reveal that at room temperature, 3 and 4 exhibit yellow-green thermally activated delayed fluorescence in the crystalline state with maximum emission wavelengths at 558 and 549 nm, respectively. The emission yields are close to unity. Quantum chemical calculations suggest that the emission of 4 originates from the (σ + X) → π* excited state that possesses strong intraligand charge-transfer character. The luminescent properties of four-coordinate Au(i) complex (5) possessing a tetrahedral geometry are discussed on the basis of the emission spectra and decay times measured in a temperature range of 309-77 K.

The interplay of non-covalent interactions determining the antiparallel conformation of (isocyanide)gold(i) dimers

Ligand⋯ligand contacts, including a novel n → π* interaction involving an isocyanide group as the acceptor, determine the persistent antiparallel conformation of dimers of (isocyanide)Au(i) complexes in their crystal structures.

Polarized Supramolecular Aggregates Based on Luminescent Perhalogenated Gold Derivatives

The reaction of [Au(C₆F₅)(tht)] (tht = tetrahydrothiophene) with 1,3,5-triaza-7-phosphaadamantane (PTA) and 3,7-diacetyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane (DAPTA) leads to the formation of [Au(C₆F₅)(phosph)] (phosph = PTA, 1; phosph = DAPTA, 2). The compounds are slightly soluble in water and aggregate at higher concentrations, giving rise to the formation of needle- and rodlike structures (1) and well-organized spherical aggregates (2). Compounds 1 and 2 were reacted with AgPF₆, giving rise to the formation in all cases of luminescent water-soluble 1:1 Au···Ag heterometallic complexes, as evidenced by X-ray crystal structure determination. The use of different silver salts that differ on the counterion induces changes in the resulting luminescence and aggregation morphology.

Polypyridyl-functionalizated alkynyl gold(i) metallaligands supported by tri- and tetradentate phosphanes

The synthesis of photophysical active polytopic alkynyl gold(i) metallaligands and preliminary studies of their interaction with metal cations are presented.

Aggregation induced emission of gold(i) complexes in water or water mixtures

Gold(i) complexes are an expanding area of investigation due to the possibility of giving rise to supramolecular aggregates with particular morphologies that can be modulated together with their luminescent properties.

The interplay between fluorescence and phosphorescence with luminescent gold(i) and gold(iii) complexes bearing heterocyclic arylacetylide ligands

The photophysical properties of a series of gold(i) [LAu(C 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 CR)] (L = PCy₃ (1a-4a), RNC (5a), NHC (6a)) and gold(iii) complexes [Au(C^N^C)(CCR)] (1b-4b) bearing heterocyclic arylacetylide ligands with narrow band-gap are compared. The luminescence of both series are derived from an intraligand transition localized on the arylacetylide ligand (ππ*(CCR)) but 1a-3a displayed prompt fluorescence (τ_PF = 2.7-12.0 ns) while 1b-3b showed mainly phosphorescence (τ_Ph = 104-205 μs). The experimentally determined intersystem crossing (ISC) rate constants (k_ISC) are on the order of 10⁶ to 10⁸ s^-1 for the gold(i) series (1a-3a) but 10¹⁰ to 10¹¹ s^-1 for the gold(iii) analogues (1b-3b). DFT/TDDFT calculations have been performed to help understand the difference in the k_ISC between the two series of complexes. Owing to the different oxidation states of the gold ion, the Au(i) complexes have linear coordination geometry while the Au(iii) complexes are square planar. It was found from DFT/TDDFT calculations that due to this difference in coordination geometries, the energy gap between the singlet and triplet excited states (ΔE_ST) with effective spin-orbit coupling (SOC) for Au(i) systems is much larger than that for the Au(iii) counterparts, thus resulting in the poor ISC efficiency for the former. Time-resolved spectroscopies revealed a minor contribution (<2.9%) of a long-lived delayed fluorescence (DF) (τ_DF = 4.6-12.5 μs) to the total fluorescence in 1a-3a. Attempts have been made to elucidate the mechanism for the origins of the DF: the dependence of the DF intensity with the power of excitation light reveals that triplet-triplet annihilation (TTA) is the most probable mechanism for the DF of 1a while germinate electron-hole pair (GP) recombination accounts for the DF of 2a in 77 K glassy solution (MeOH/EtOH = 4 : 1). Both 4a and 4b contain a BODIPY moiety at the acetylide ligand and display only ¹IL(ππ*) fluorescence with negligible phosphorescence being observed. Computational analyses attributed this observation to the lack of low-lying triplet excited states that could have effective SOC with the S₁ excited state.

Tuning supramolecular aurophilic structures: the effect of counterion, positive charge and solvent

The synthesis of different cationic gold(i) complexes gave rise to the formation of unexpected supramolecular assemblies in water going from rod-like structures to vesicles and square-like structures.

Supramolecular Hydrogelators and Hydrogels: From Soft Matter to Molecular Biomaterials

In this review we intend to provide a relatively comprehensive summary of the work of supramolecular hydrogelators after 2004 and to put emphasis particularly on the applications of supramolecular hydrogels/hydrogelators as molecular biomaterials. After a brief introduction of methods for generating supramolecular hydrogels, we discuss supramolecular hydrogelators on the basis of their categories, such as small organic molecules, coordination complexes, peptides, nucleobases, and saccharides. Following molecular design, we focus on various potential applications of supramolecular hydrogels as molecular biomaterials, classified by their applications in cell cultures, tissue engineering, cell behavior, imaging, and unique applications of hydrogelators. Particularly, we discuss the applications of supramolecular hydrogelators after they form supramolecular assemblies but prior to reaching the critical gelation concentration because this subject is less explored but may hold equally great promise for helping address fundamental questions about the mechanisms or the consequences of the self-assembly of molecules, including low molecular weight ones. Finally, we provide a perspective on supramolecular hydrogelators. We hope that this review will serve as an updated introduction and reference for researchers who are interested in exploring supramolecular hydrogelators as molecular biomaterials for addressing the societal needs at various frontiers.

Organogold oligomers: exploiting iClick and aurophilic cluster formation to prepare solution stable Au4 repeating units

Cluster formation via multiple gold–gold bonds provides sufficient thermodynamic driving force to overcome entropic penalties to link multiple units and create solution stable organogold oligomers.