1,2,4-triazine derived binuclear lead(ii) complexes: synthesis, spectroscopic and structural investigations and application in organic light-emitting diodes (OLEDs).

Two novel binuclear complexes of Pb(ii) were synthesized by reacting a 3-(2-pyridyl)-5-(4-methoxyphenyl)-1,2,4-triazine (PMPT) ligand with different anionic co-ligands (1: bromide, 2: acetate and isothiocyanate) in a 1 : 1 molar ratio of PMPT ligands to lead(ii) salts. The complexes, [Pb2(µ-PMPT)2Br4] (1) and [Pb2(µ-PMPT)2((µ-CH3COO)2(NCS)2] (2), were characterized using various physicochemical techniques such as CHN analysis, FT-IR spectroscopy, and 1H NMR spectroscopy. Additionally, their structures were determined using single-crystal X-ray diffraction. Based on the obtained structural parameters, complex 1 exhibited a PbN3Br2 environment, while complex 2 displayed a PbN4O3 environment, with holodirected and hemidirected coordination spheres, respectively. Within the crystal network of the complexes, there were interactions involving C-H⋯X (X: O, S, N) as well as π-π stacking. The Pb(ii) complexes were further investigated for their potential use as the emitting layer in organic light-emitting devices (OLEDs). The current-voltage and luminescence-voltage characteristics, as well as the electroluminescence (EL) properties of the complexes, were studied.

Coordination of a triazine ligand with CuII and AgI investigated by spectral, structural, theoretical and docking studies.

Two complexes of 5-phenyl-3-(pyridin-2-yl)-1,2,4-triazine (PPTA), namely (ethanol-κO)bis(nitrato-κO)[5-phenyl-3-(pyridin-2-yl-κN)-1,2,4-triazine-κN2]copper(II), [Cu(NO3)2(C14H10N4)(C2H6O)] or [Cu(NO3)2(PPTA)(EtOH)] (1), and bis[µ-5-phenyl-3-(pyridin-2-yl)-1,2,4-triazine]-κ3N1:N2,N3;κ3N2,N3:N1-bis[(nitrato-κO)silver(I)], [Ag2(NO3)2(C14H10N4)2] or [Ag2(NO3)2(µ-PPTA)2] (2), were prepared and characterized by elemental analysis, FT-IR spectroscopy and single-crystal X-ray diffraction. The X-ray structure analysis of 1 revealed a copper complex with square-pyramdial geometry containing two O-donor nitrate ligands along with an N,N'-donor PPTA ligand and one O-donor ethanol ligand. In the binuclear structure of 2, formed by the bridging of two PPTA ligands, each Ag atom has an AgN3O environment and square-planar geometry. In addition to the four dative interactions, each Ag atom interacts with two O atoms of two nitrate ligands on adjacent complexes to complete a pseudo-octahedral geometry. Density functional theory (DFT) calculations revealed that the geometry around the Cu and Ag atoms in 1opt and 2opt (opt is optimized) for an isolated molecule is the same as the experimental results. In 1, O-H...O hydrogen bonds form R12(4) motifs. In the crystal network of the complexes, in addition to the hydrogen bonds, there are π-π stacking interactions between the aromatic rings (phenyl, pyridine and triazine) of the ligands on adjacent complexes. The ability of the ligand and complexes 1 and 2 to interact with ten selected biomacromolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS, Top II and B-DNA) was investigated by docking studies. The results show that the studied compounds can interact with proteins better than doxorubicin (except for TrxR and Top II).

Spectral, structural and theoretical study of the effects of thiocyanato and dicyanamido ligands on the geometry of PbII complexes containing a triazinic ligand.

Two lead(II) complexes of 5,6-bis(furan-2-yl)-3-(pyridin-2-yl)-1,2,4-triazine (DFPT), namely one-dimensional (1D) catena-poly[[bis[5,6-bis(furan-2-yl)-3-(pyridin-2-yl-κN)-1,2,4-triazine-κN2]lead(II)]-di-µ-thiocyanato-κ2N:S;κ2S:N], [Pb(NCS)2(C16H10N4O2)2]n, 1, and binuclear di-µ-dicyanamido-κ2N1:N5;κ2N5:N1-bis{[5,6-bis(furan-2-yl)-3-(pyridin-2-yl-κN)-1,2,4-triazine-κN2](nitrato-κ2O,O')lead(II)}, [Pb2(C2N3)2(NO3)2(C16H10N4O2)4], 2, as well as DFPT itself, were prepared and identified by elemental analysis, FT-IR, 1H NMR spectroscopy and single-crystal X-ray structural analyses. In the double-chain 1D coordination polymer of 1 and the binuclear structure of 2, the Pb atom has a hemidirected-PbN6S2 and a rare holodirected-PbN6O2 environment, respectively, with a distorted cubic geometry. All the coordination modes of dicyanamide ligands within lead complexes were studied using the Cambridge Structural Database (CSD) to compare them with the structures of 1 and 2. In addition to hydrogen bonds, the crystal networks are stabilized by π-π stacking interactions between the triazine, furyl and pyridine aromatic rings. The most stable theoretical structures of the title compounds predicted by density functional theory (DFT) calculations were compared with the solid-state results.

Sonochemical synthesis and characterization of three nano zinc(II) coordination polymers; Precursors for preparation of zinc(II) oxide nanoparticles.

Nanostructures of three Zinc(II) coordination polymers, [Zn(NNO)2(H2O)4]n (1), [Zn(PNNO)2(H2O)2]n (2) and [Zn(H2O)6]·(INNO)2 (3) {NNO: Nicotinic acid N-oxide, PNNO: Picolinic acid N-oxide and INNO: Isonicotinic acid N-oxide}, have been synthesized by a sonochemical process and reaction of ligands with Zn(CH3COO)2. The Zinc(II) oxide nano-particles have been synthesized from thermolysis of [Zn(NNO)2(H2O)4]n (1), [Zn(PNNO)2(H2O)2]n (2) and [Zn(H2O)6]·(INNO)2 (3) at two different methods (with surfactant and without surfactant) and two temperatures (200 and 600°C). The ZnO nanoparticles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Comparison of the SEM images of ZnO nano-particles at two different methods and temperatures shows that higher temperature results in an increasing of agglomeration and thus small and spherical ZnO particles with good separation were produced by thermolysis of compounds at 200°C and by use of surfactant.

Cd(II) and Zn(II) coordination polymers assembled from benzoyltrifluoroacetone and 1,2-bis(4-pyridyl)ethane ancillary ligands.

Two novel cadmium(II) and zinc(II) metal-organic coordination polymers with a beta-diketone and N-donor ancillary ligands, [Cd(bpe)(btfa)2]n (1) and [Zn(bpe)(btfa)2]n (2), (Hbtfa = benzoyltrifluoroacetone and bpe = 1,2-bis(4-pyridyl)ethane), have been prepared and characterized by elemental analysis, IR and 'H NMR spectroscopy, and studied by thermal gravimetric analysis as well as single crystal X-ray diffraction. The crystal and molecular structures of 1 and 2 have been solved by X-ray diffraction and they turned out to be one-dimensional polymers with zigzag (1) and linear (2) dispositions of the metal atoms. These one-dimensional polymers are further connected to form a 3D supramolecular network by C-H--O and C-H--F interactions. Thermal stabilities of these polymeric complexes have also been investigated.

µ-Pyrazine-bis-[tetra-aqua-cadmium(II)] µ-pyrazine-bis-[tetra-acetato-cadmium(II)].

In the title dinuclear ionic complex, [Cd(2)(C(4)H(4)N(2))(H(2)O)(8)][Cd(2)(CH(3)CO(2))(8)(C(4)H(4)N(2))], the cation and anion are disordered equally over a site with symmetry mmm. The Cd(II) ions and the N atoms of the bridging pyrazine ligand lie on the inter-section of two crystallographic mirror planes. The C atoms of the bridging pyrazine ligand lie on one of these mirror planes, and the acetate groups and water mol-ecules lie across the inter-secting mirror planes. Each Cd(II) atom in the cation is five-coordinated by four O atoms from four water mol-ecules and one N atom from the bridging pyrazine ligand, whereas each Cd(II) in the anion is nine-coordinated by four pairs of O atoms from the bidentate acetate ligands and one N atom from the bridging pyrazine ligand. In the crystal structure, each anion is surrounded by eight nearest-neighbour cations and vice versa. The crystal structure is stabilized by ionic inter-actions as well as by C-H⋯O inter-actions.