Homoleptic Cyclic Trinuclear d10 Complexes: From Self-Association via Metallophilic and Excimeric Bonding to the Breakage Thereof via Oxidative Addition, Dative Bonding, Quadrupolar and Heterometal Bonding Interactions

Trinuclear coinage metal metallacycles are obtained when two-coordinate metals are bonded to C, N or N, N anionic ligands of the proper symmetry to form cycles where metals alternate with bridging ligands. Cyclotrimers often exhibit semiplanar structures and mostly columnar or finite stacking in the solid state by means of metallophilic interactions. They show some peculiar properties with an impact on many different fields such as supramolecular architectures, luminescence, molecular recognition, host-guest chemistry, and acid-base chemistry. The comprehensive evaluation of the data shows that, depending on the nature of the central metal and bridging ligand, there is a fine balance of the energy involved in the inter-trimer bond cleavages and the energy gained from the formation of new intermolecular electrostatic interactions, proceeding occasionally to the chemical extreme of redox processes. In this review, a number of important developments are highlighted and systematically analyzed along with structural and computational data and chemical properties to rationalize and build a unifying leitmotif for this chemistry; the focus is made on the authors’ contributions in these areas

Insights into Molecular Structures and Optical Properties of Stacked [Au-3(RN=CR ')(3)](n) Complexes

The molecular structure of stacked cyclic trinuclear gold(I) complexes [Au-3(RN=CR'(3)](n), with n = 1-4, where R = H, methyl (Me), cyclopentyl ((c)Pe), and phenyl (Ph) and R' = OH and methoxy (OMe) were studied computationally at the second-order Moller-Plesset (MP2) and density functional theory (DFT) levels of theory. At the DFT level, the aurophilic and dispersion interactions were accounted for by using the TPSS functional in combination with the semiempirical D3 correction. The structure optimizations yielded the lowest energy for a slided stacked structure of the [Au-3(HN=COH)(3)](2) dimer, where monomers are slightly shifted relative to one another. At the MP2 level, the slided structure is 32 kJ/mol more stable than the staggered dimer structure, which in turn is energetically 11 kJ/mol below the eclipsed structure. The calculations show that aromatic ligands lead to a planar and prismatic structure of [Au-3(PhN=COMe)(3)](4), whereas for [Au-3('PeN=COMe)(3)](4), a chair conformation is obtained due to steric effects. Excitation energies were calculated for [Au-3(RN=CR')(3)] and [Au-3(RN=CR'(3)](2) with R = H, Me, and 'Pe and R' = OH and OMe at the time-dependent DFT level using the optimized molecular structures of the singlet ground state. To simulate the luminescence spectra, the lowest triplet excitation energy was also calculated for the molecular structure of the lowest triplet state. The calculated excitation energies of [Au-3(HN=COH)(3)] and [Au-3(HN=COH)(3)](2) are compared with values obtained at the approximate singles and doubles coupled cluster (CC2) and the second-order algebraic diagrammatic construction (ADC(2)) levels of theory. The calculated absorption and emission energies reproduce the experimental trends, with extremely large Stokes shifts. A solvoluminescence mechanism is also proposed.Peer reviewe

Jahn - Teller Distortion in the Phosphorescent Excited State of Three-Coordinate Au(I) Phosphine Complexes

This article discusses three-coordinate Au(I) phosphine complexes

Bioinspired Synthesis of Silver Nanoparticles for the Remediation of Toxic Pollutants and Enhanced Antibacterial Activity

Article asserts that this research presents a novel and environmentally friendly approach for the synthesis of multifunctional nanobiocomposites for the efficient removal of toxic heavy metal and dye, as well as the disinfection of wastewater microorganisms. The synthesized bioinspired nanocomposite KAC-CS-AgNPs could be an innovative solution for effective and sustainable wastewater treatment and has great potential for commercial applications

Systematic Control of the Orientation of Organic Phosphorescent Pt Complexes in Thin Films for Increased Optical Outcoupling

Orienting light‐emitting molecules relative to the substrate is an effective method to enhance the optical outcoupling of organic light‐emitting devices. Platinum(II) phosphorescent complexes enable facile control of the molecular alignment due to their planar structures. Here, the orientation of Pt(II) complexes during the growth of emissive layers is controlled by two different methods: modifying the molecular structure and using structural templating. Molecules whose structures are modified by adjusting the diketonate ligand of the Pt complex, dibenzo‐(f,h)quinoxaline Pt dipivaloylmethane, (dbx)Pt(dpm), show an ≈20% increased fraction of horizontally aligned transition dipole moments compared to (dbx)Pt(dpm) doped into a 4,4′‐bis(N‐carbazolyl)‐1,1′‐biphenyl, CBP, host. Alternatively, a template composed of highly ordered 3,4,9,10‐perylenetetracarboxylic dianhydride monolayers is predeposited to drive the alignment of a subsequently deposited emissive layer comprising (2,3,7,8,12,13,17,18‐octaethyl)‐21H,23H‐porphyrinplatinum(II) doped into triindolotriazine. This results in a 60% increase in horizontally aligned transition dipole moments compared to the film deposited in the absence of the template. The findings provide a systematic route for controlling molecular alignment during layer growth, and ultimately to increase the optical outcoupling in organic light‐emitting diodes.Pt(II) complex orientation is controlled by modifying the molecular structure and structural templating. Molecules with modified structures show ≈20% increased fraction of horizontally aligned transition dipole moments (TDMs) when doped into a host. Alternatively, a highly ordered molecular template drives the alignment of a subsequently deposited polycrystalline emissive layer, showing a 60% increase in horizontally aligned TDMs versus without template.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151333/1/adma201900921.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151333/2/adma201900921_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151333/3/adma201900921-sup-0001-S1.pd

Cupriphication of gold to sensitize d10–d10 metal–metal bonds and near-unity phosphorescence quantum yields

Outer-shell s0/p0 orbital mixing with d10 orbitals and symmetry reductionuponcupriphicationofcyclic trinucleartrigonal-planargold(I) complexes are found to sensitize ground-state Cu(I)–Au(I) covalent bonds and near-unity phosphorescence quantum yields. Heterobimetallic Au4Cu2 {[Au4(μ-C2,N3-EtIm)4Cu2(μ-3,5-(CF3)2Pz)2], (4a)}, Au2Cu {[Au2(μ-C2,N3-BzIm)2Cu(μ-3,5-(CF3)2Pz)], (1) and [Au2(μ-C2, N3-MeIm)2Cu(μ-3,5-(CF3)2Pz)], (3a)}, AuCu2 {[Au(μ-C2,N3-MeIm)Cu2(μ3,5-(CF3)2Pz)2], (3b) and [Au(μ-C2,N3-EtIm)Cu2(μ-3,5-(CF3)2Pz)2], (4b)} and stacked Au3/Cu3 {[Au(μ-C2,N3-BzIm)]3[Cu(μ-3,5-(CF3)2Pz)]3, (2)} formuponreactingAu3 {[Au(μ-C2,N3-(N-R)Im)]3 ((N-R)Im = imidazolate; R =benzyl/methyl/ethyl =BzIm/MeIm/EtIm)} with Cu3 {[Cu(μ-3,5(CF3)2Pz)]3 (3,5-(CF3)2Pz = 3,5-bis(trifluoromethyl)pyrazolate)}. The crystal structures of 1 and 3a reveal stair-step infinite chains whereby adjacent dimer-of-trimer units are noncovalently packed via twoAu(I)⋯Cu(I)metallophilicinteractions,whereas 4a exhibitsa hexanuclear cluster structure wherein two monomer-of-trimer units are linked by a genuine d10–d10 polar-covalent bond with ligandunassisted Cu(I)–Au(I) distances of 2.8750(8) Å each—the shortest such an intermolecular distance ever reported between any two d10 centers so as to deem it a “metal–metal bond” vis-à-vis “metallophilic interaction.” Density-functional calculations estimate 35– 43kcal/molbindingenergy,akintotypicalM–Msingle-bondenergies. Congruently, FTIR spectra of4a showmultiple far-IR bands within 65– 200 cm−1, assignable to vCu-Au as validated by both the Harvey–Gray method of crystallographic-distance-to-force-constant correlation and dispersive density functional theory computations. Notably, the heterobimetallic complexes herein exhibit photophysical properties that are favorable to those for their homometallic congeners, due to threefold-to-twofold symmetry reduction, resulting in cuprophilicsensitizationinextinctioncoefficientandsolid-state photoluminescence quantum yields approaching unity (ΦPL = 0.90–0.97 vs. 0–0.83 for Au3 and Cu3 precursors), which bodes well for potential future utilization in inorganic and/or organic LED applications