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

New Coordination Polymers of Copper(I) and Silver(I) with Pyrazine and Piperazine: A Step Toward “Green” Chemistry and Optoelectronic Applications

Five coordination polymers and one hexanuclear cluster have been obtained, and their crystal structures were determined upon reaction of Cu­(I) or Ag­(I) precursors with pyrazine (Pyz) or piperazine (Ppz). Five complexes are mixed-imine-ligand with anionic-fluorinated pyrazolate [3,5-(CF₃)₂Pz]⁻ ([Pz^F]⁻) besides Pyz or Ppz, whereas the sixth had the neutral diimine as a single chromophore. Complexes <b>1</b>–<b>3</b> are isomers of the same Cu/Pz^F/Pyz composition with the same or different unit cell stoichiometry, namely, {Cu₆[3,5-(CF₃)₂Pz]₆­(Pyz)₃­(CH₂Cl₂)}_∞ (<b>1</b>·CH₂Cl₂), {Cu₂[3,5-(CF₃)₂Pz]}₂­(Pyz)₂­·toluene}_∞ (<b>2</b>·toluene), and {Cu₃[3,5-(CF₃)₂Pz]₃­(Pyz)_1.5­·1.5benzene}_∞ (<b>3</b>·1.5benzene), respectively. Altering only the metal attains {Ag₆[3,5-(CF₃)₂Pz]₆­(Pyz)₂­·2benzene} (<b>4</b>·2benzene), while also changing the neutral diimine attains {Ag₂[3,5-(CF₃)₂Pz]₂­(Ppz)}_∞ (<b>5</b>). Using Pyz without an anionic imine yields {[Cu­(Pyz)­(MeCN)₂]­[BF₄]}_∞ (<b>6</b>). The crystal structure of <b>1</b> shows two trimers linked together with two pyrazine ligands. Crystals of <b>2</b> represent a metal–organic framework (MOF-TW1) with significant surface area (1278 m²/g) and porosity (23.7% void volume) without considering toluene adsorbates in channels. MOF-TW1 was obtained serendipitously upon a reaction attempt to attain a mixed-metal product, instead attaining a Cu­(I)-only product with interconnected four-coordinate dinuclear units. Likewise, <b>3</b> was obtained through a transmetalation of all Ag atoms in <b>4</b> to replace them by Cu atoms. Three reactions (to obtain <b>1</b>, <b>4</b>, and <b>5</b>) were successfully carried out by both solvent-mediated and solventless transformations, whereas <b>2</b> and <b>3</b> were obtained only by solvent-mediated reactions, while <b>6</b> was attainable only by solventless transformations. The solventless transformations occurred either by sublimation and vapor diffusion or by mechanical grinding at ambient laboratory conditionswithout the aid of heating, high pressure, vacuum, or any automated equipment. All transformations could be monitored by the human eye as the reaction progresses, as evidenced by progressive discoloration and/or luminescence changes. All crystal structures were obtained with the aid of conventional crystal growth methods from organic solvents for bulk products obtained from both solvelntless and solvent-mediated reactions. Powder X-ray diffraction was used to compare bulk products with one another and the crystallographic products. All Cu­(I) products are colored and nonluminescent; the progress of their vapor diffusion-based solventless reactions can be followed by gradual discoloration of white solid reactants and/or quenching precursor’s phosphorescence. Both Ag­(I) products were colorless with <b>4</b> being luminescent but not <b>5</b>

Pyrene Bearing Azo-Functionalized Porous Nanofibers for CO2 Separation and Toxic Metal Cation Sensing

This article describes the construction of a novel luminescent azo-linked polymer from 1,3,6,8-tetra(4--aminophenyl)pyrene using a copper(I)-catalyzed oxidative homocoupling reaction