Light-Induced Photochemical Changes in Copper(I) Thiocyanate Complexes Decorated with Halopyridines: Optical Memory Manifestation

We report on the photoluminescence of {CuSCN(3-XPy)2}n crystals (X = Br, Cl; Py = pyridine). Laser excitation at 266 nm for CuSCN(3-BrPy)2 at 78 K results in a decrease in the luminescence intensity with increasing irradiation time. Heating the sample to 298 K and recooling to 78 K results in recovery of the original luminescence intensity, hence manifesting an optical memory effect. Laser irradiation at longer or shorter wavelengths fails to produce a reduction in emission intensity. Interestingly, CuSCN(3-ClPy)2, despite being isomorphic, does not undergo emission intensity changes regardless of laser irradiation wavelength variation. Density functional theory (DFT) and time-dependent DFT calculations were performed on an adjacent chain model to explore the photochemical change that occurs upon laser irradiation. The observed reduction in luminescence intensity is attributed to photoinduced electron transfer quenching in which Cu(I) is oxidized to a nonluminescent Cu(II) with capture of the halogen by a neighboring SCN ligand on the adjacent coordination polymer chain

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

Flavin-Catalyzed Insertion of Oxygen into Rhenium-Methyl Bonds

Article discussing flavin-catalyzed insertion of oxygen into rhenium-methyl bonds

Light-Induced Photochemical Changes in Copper(I) Thiocyanate Complexes Decorated with Halopyridines: Optical Memory Manifestation

We report on the photoluminescence of {CuSCN­(3-XPy)₂}_<i>n</i> crystals (X = Br, Cl; Py = pyridine). Laser excitation at 266 nm for CuSCN­(3-BrPy)₂ at 78 K results in a decrease in the luminescence intensity with increasing irradiation time. Heating the sample to 298 K and recooling to 78 K results in recovery of the original luminescence intensity, hence manifesting an optical memory effect. Laser irradiation at longer or shorter wavelengths fails to produce a reduction in emission intensity. Interestingly, CuSCN­(3-ClPy)₂, despite being isomorphic, does not undergo emission intensity changes regardless of laser irradiation wavelength variation. Density functional theory (DFT) and time-dependent DFT calculations were performed on an adjacent chain model to explore the photochemical change that occurs upon laser irradiation. The observed reduction in luminescence intensity is attributed to photoinduced electron transfer quenching in which Cu­(I) is oxidized to a nonluminescent Cu­(II) with capture of the halogen by a neighboring SCN ligand on the adjacent coordination polymer chain