Group IIB metal complexes with a multidentate N-donor tecton 3,4-bis(2-pyridyl)-5-(3-pyridyl)-1,2,4-triazole: Metal-directed assemblies, crystal structures and properties

Crystallization Induced Enhanced Emission in Two New Zn(II) and Cd(II) Supramolecular Coordination Complexes with the 1-(3,4-Dimethylphenyl)-5-Methyl-1H-1,2,3-Triazole-4-Carboxylate Ligand

Two new d¹⁰ metal supramolecular metal-organic frameworks (SMOFs) with general formula [ML₂(H₂O)₂]_n (M = Zn, Cd) have been synthetized using the sodium salt of the anionic 1-(3,4-dimethylphenyl)-5-methyl-1H-1,2,3-triazole-4-carboxylate ligand (Na⁺L^-). Both SMOFs have been structurally characterized by single-crystal X-ray diffraction analysis and IR spectroscopy. The compounds are isostructural and form supramolecular aggregates via hydrogen bonds with the presence of less common dihydrogen bonds. Interestingly, they show ionic conductivity and porosity. The luminescent properties have been also studied by means of the excitation and emission spectra. Periodic DFT and molecular TD-DFT calculations have been used to unravel the emergence of luminescence in the otherwise non-emitting 1-(3,4-dimethylphenyl)-5-methyl-1H-1,2,3-triazole-4-carboxylate ligand once incorporated in the SMOFs. Our results also illustrate the importance of considering the dielectric environment in the crystal when performing excited state calculations for isolated fragments to capture the correct electronic character of the low-lying states, a practice which is not commonly adopted in the community.

Crystal structure of catena-poly[dichlorido-(μ-ethane-1,2-diyl-bis-(pyridyl-4-carboxylate-κN:N′)mercury(II)], C15H14Cl2HgN2O4

C15H14Cl2HgN2O4, triclinic, P1̅, (no. 2), a = 7.8177(4) Å, b = 7.9757(4) Å, c = 15.2165(7) Å, α = 76.444(2)°, β = 79.660(2)°, γ = 77.353(2)°, V = 891.71(8) Å3, Z = 2, R gt(F) = 0.0300, wR ref(F 2) = 0.041, T = 297(2) K.

One-dimensional coordination polymers generated from a new triazole bridging ligand and HgX2 (X = Cl, Br and I): characterization and luminescent properties

The new 4-amino-1,2,4-triazole asymmetric bridging ligand 4-amino-5-(pyridin-3-yl)-3-[4-(pyridin-4-yl)phenyl]-4H-1,2,4-triazole (L) has been used to generate three novel isomorphic one-dimensional coordination polymers, viz. catena-poly[[tris[dichloridomercury(II)]-bis{μ(3)-4-amino-5-(pyridin-3-yl)-3-[4-(pyridin-4-yl)phenyl]-4H-1,2,4-triazole}] acetonitrile monosolvate], {[Hg(3)Cl(6)(C(18)H(14)N(6))(2)]·CH(3)CN}(n), (I), and the bromido, {[Hg(3)Br(6)(C(18)H(14)N(6))(2)]·CH(3)CN}(n), (II), and iodido, {[Hg(3)I(6)(C(18)H(14)N(6))(2)]·CH(3)CN}(n), (III), analogs. The asymmetric ligand acts as a tridentate ligand to coordinate the three different Hg(II) centers (two of which are symmetry-related). Two ligands and two symmetry-related Hg(II) centers form centrosymmetric rectangular units which are linked into one-dimensional chains via the other unique Hg atoms, which sit on mirror planes. The chains are elaborated into a three-dimensional structure via interchain hydrogen bonds. The acetonitrile solvent molecules are located in ellipsoidal cavities. The luminescent character of these three coordination complexes was investigated in the solid state.

Diaquabis[5-(pyrazin-2-yl-κN1)-3-(pyridin-4-yl)-1H-1,2,4-triazol-1-ido-κN1]cobalt(II) methanol disolvate

The Co^II ion in the title mononuclear compound, [Co(C₁₁H₇N₆)₂(H₂O)₂]·2CH₃OH, is located on an inversion center and is six-coordinated in a distorted octa­hedral geometry defined by four N atoms from two deprotonated 5-(pyrazin-2-yl-κN)-3-(pyridin-4-yl)-1H-1,2,4-triazol-1-ide (ppt) ligands and two water mol­ecules. In the crystal, the complex mol­ecules and lattice methanol mol­ecules are linked via O—H⋯N and O—H⋯O hydrogen bonds, generating a two-dimensional supra­molecular network parallel to (001). π–π inter­actions between the triazole and pyrazine rings and between the pyridine rings are present [centroid–centroid distances = 3.686 (3) and 3.929 (4) Å, respectively].