Synthesis,spectroscopic properties and DFT calculations of a novel multipolar azo dye and its zinc(II) complex

The synthesis and photophysical properties of 5-(diethylamino)-4-[(E)-(4-nitrophenyl)diazenyl]-2-(1,3-benzoxazol-2-yl)phenol (AB-HBO) and its zinc complex were examined. The organic molecule acts as a pH sensitive chromophore and as mononegative ligand for zinc(II) ion. Structural features and photophysical properties of AB-HBO were studied. The solvatochromic blue shift, shown by the ligand in its neutral form, is widely enhanced in its deprotonated form. The color solution ranges from red-orange to violet and blue-green as function of the electronic density deformation. Fluorescence spectra were recorded on both ligand and zinc complex solutions. (TD)DFT calculations have been performed to rationalize the absorbance of chromophore and complex.     

The synthesis and photodynamic properties of meso-substituted, cationic porphyrin derivatives in HeLa cells

A series of asymmetric porphyrins with varying substituents, such as 4-hydrophenyl and N-methyl-4-pyridyl, were synthesized and characterized and their cell uptake, intracellular localization, cytotoxicities and phototoxicities were evaluated in vitro. The most phototoxic of the porphyrins synthesized, 5,10-di-(N-methyl-4-pyridyl)-15,20-(4-hydroxyphenyl)-21,23H-porphyrin, which was mainly localized in the mitochondria and displayed low levels of dark toxicity toward human cancer HeLa cells, offers potential application in photodynamic therapy.     

One-dimensional helical Cu(II) coordination polymer: Synthesis,structures, and properties

One new Cu(II) coordination polymer (1) based on 6,6′-dihydroxy-2,2′-bipyridine (H₂dhbp) was successfully prepared, with the formula of [Cu(μ₂-OH)(Hdhbp)]_n (1). Single-crystal X-ray analysis shows that compound 1 crystallizes in orthorhombic chiral space group P2₁2₁2₁ and exhibits a left-handed (L) helical [Cu(μ₂-OH)]_n-chain. Luminescence of 1 exhibits a broad emission around 440 nm, attributing to the metal to ligand charge transfer (MLCT). Magnetic susceptibility shows antiferromagnetic coupling within compound 1. Cyclic voltammetry (CV) experiments indicate a potential water oxidation electrocatalyst.     

Synthesis,structure and properties of a new NH-1,2,3-triazole-based octanuclear copper(II) complex

An octanuclear copper complex, [Cu₈(L)₁₀(OH)₄Cl₂·(DMF)₂]·2DMF ( HL= 4-(2-bromophenyl)-2H-1,2,3-triazole) has been synthesized. Single crystal diffraction reveals that it crystallizes in the triclinic space group P − 1. The complex shows fluorescent quenching compared with the free ligand. The {Cu₈} displays overall strong antiferromagnetic (AF) coupling via hydroxyl groups, κ₂-N,N-trizaoles and κ₃-N,N,N-trizaoles, and the complex exhibits AF ordering under low temperature with T_N = 8.5 K.     

Molecular recognition of amines by a chiral Zn(II) porphyrin complex

Equilibria of the reactions of a Zn(II) `picket-fence' porphyrin complex bearing optically active substituents with chiral amines were studied. Stability constants were determined by spectrophotometric titration in dichloromethane solution. Chiral recognition in the complexation of amine to the α,β,α,β-isomer of the complex was observed for 1-(1-naphthyl)ethylamine with the ratio of the binding constant of K_S/K_R=2.4.     

Synthesis,structure, and properties of dinuclear copper (II) complex with a (H2O)12 cluster

A novel pyrazole complex, namely [Cu₂(4,4′-bpy)₂(2,2′-bpy)(L)₂]·6H₂O has been synthesized under mild condition (4,4′-bpy = 4,4′-bipyridine, 2,2′-bpy = 2,2′-bipyridine). We report the structural evidence in the solid state of discrete water hexamers chair-like conformation. These units were found to act as supramolecular glue in the aggregation of dinuclear copper (II) complex to give a three dimensional network through hydrogen-bonding. The preliminary investigation on the electrochemical property and fluorescence property of the complex are presented.     

Synthesis,crystal structure and relevant antiproliferative activity against Toxoplasma gondii of a new binuclear Co(II) complex

The crystal structure of [(HPClNOL)Co(-μ-Cl₂)Co(HPClNOL)](ClO₄)₂ 1 (HPClNOL: 1-(bis-pyridin-2-ylmethyl-amino)-3-chloropropan-2-ol) revealed a distorted octahedral geometry around both Co(II) centers. The coordination plane comprised one tertiary amine, one alcohol in the protonated form and two chloride which link the two Co(II) centers, resulting in the binuclear arrangement. Two pyridine nitrogen atoms are coordinated and occupy the axial sites. Investigations in solid state and in solution (dimethylformamide) carried out by electronic spectroscopy suggest that the arrangement in the solid state changes in solution. Furthermore, ESI(+)-MS and conductivimetry studies indicated the formation of mononuclear species in solution in agreement with the lability of the chloride ligands. Complex 1 reduced the growth of Toxoplasma gondii infecting LLC-MK2 host cells. After treatment this complex reduced T. gondii growth by 55%, the ligand HPClNOL had no effect on parasite growth and sulfadiazine (SDZ), traditional terapeutic compound for this parasite, was effective only after 48 h of treatment. These results suggest the relevance of the cobalt ion on the anti-toxoplasma activity.     

Polychelates of poly(acrylic acid-co-acrylamide)with Cu(II), Co(II), and Ni(II) Synthesis and properties

SUMMARY Polychelates were obtained by addition of an aqueous solution of the poly(acrylic acid-co-acrylamide) to an aqueous solution of Cu(II), Co(II), and Ni(II). All the polychelates were insoluble in water and in common organic solvents. The polychelates were characterized by elemental analysis, FT-IR spectroscopy thermogravimetry, and showed tetrahedral arrangement for Co(II) and Ni(II). Magnetic and conductivity studies for all the polychelates were also carried out. The poly(acrylic acid-co-acrylamide) behaved as semiconductor. Received: 25 July 1997/Revised version: 1 December 1997/Accepted: 5 December 1997     

Synthesis, crystal structure and luminescent properties of a thiocyanato bridged two-dimensional heteronuclear polymeric complex of cadmium(II) and copper(II)

A novel heteronuclear polymeric complex Cd(SCN)₃Cu(en)₂NO₃ (1) (en = ethylenediamine) has been synthesized and structurally characterized. The Cd(II) atom is surrounded by three S atoms and three N atoms from four 1,3-μ-SCN⁻ and two 1,1,3-μ-SCN⁻ to attain a distorted octahedral coordination geometry. Six Cd(II) centers are linked by twelve thiocyanato bridges to form hexagonal metallocyclic unit [Cd₆(SCN)₁₂] and extend a 2D network. Moreover, a 1,1,3-μ-SCN⁻ links two cadmium and one copper metal atoms. The luminescent properties of 1 in the solid state were investigated.     

Synthesis, characterization, and properties of polychelates of poly(maleic acid-co-olefin) with Cu(II), Co(II), Ni(II), and Zn(II)

SUMMARY Polychelates of poly(maleic acid-co-olefin) with Cu(II), Co(II), Ni(II), and Zn(II) metal ions are synthesized. These compounds are characterized by FT IR, UV-vis spectroscopy, and thermal analysis. The electrical conductivity measurements are carried out. These demonstrate that at temperature close to 130°C the electrical conductivity increased to values near to the semiconductor range. The PM3 calculations are also carried to study the geometry of the polychelates. Received: 1 November 2000/Revised version: 20 March 2001/Accepted: 21 March 2001     

Synthesis,structure and magnetic properties of a tetranuclear Mn(II) complex with carbohydrazone based ligand

A new tetranuclear complex of Mn(II), [Mn₄(L)₂(CH₃OH)₂(μ-N₃)₄(N₃)₂] ∙ 2(CH₃OH) (1), was synthesized and characterized by spectroscopic methods, single-crystal X-ray diffraction analysis and TGA analysis where HL is bis-[(E)-N′-(phenyl(pyridin-2-yl)methylene)]carbohydrazide. Single crystal X-ray analysis reveals that 1 has a Mn₄ core in which Mn(II) ions are connected by azide and enolate oxygen atoms. IR spectroscopy and X-ray analysis indicate that the carbohydrazone is coordinated to the metal cores as a mononegative ligand in the enol form. The magnetic behavior of 1 was investigated between 2 and 295 K and indicated that the magnetic coupling mediated via azide bridge is ferromagnetic whereas the enolate oxygen mediates antiferromagnetic coupling that leads to overall antiferromagnetic behavior.     

Synthesis, structure and magnetic properties of a novel lead(II) complex containing nitronyl nitroxide radicals

The lead(II) complex with nitronyl nitroxide, [Pb(NIT2Py)₂(NO₃)₂] [NIT2Py = 2-(2′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide], has been prepared and characterized by magnetic and single-crystal X-ray diffraction studies. In the complex, the lead(II) ion is coordinated with two bidentate nitronyl nitroxide and two nitrate anions. The lead(II) ion shows seven-coordinate geometry. Magnetic susceptibility data for the title complex has been measured in the range 5–300 K. There are antiferromagnetic interaction between the coordinated nitronyl nitroxides (J = −19.35 cm⁻¹) and intermolecular ferromagnetic interactions. Thus, we observe the sixth periodic IVA group metal element Pb(II) ion providing an effective pathway for the magnetic exchange interaction between nitronyl nitroxide radicals.     

Synthesis of porphyrin end-capped water-soluble poly(phenylene ethynylene) and study of its optical properties

A novel Porphyrin End-Capped poly(phenylene ethynylene) (P-PPE) was synthesized by palladium-catalyzed cross-coupling reaction. Porphyrin was successfully introduced to the polymer backbone, which was confirmed by ¹H NMR, UV–Vis and Fluorescence spectroscopy. The degree of polymerization of P-PPE was characterized by both ¹H NMR and GPC analysis. UV–Vis absorption and fluorescence studies in organic solvent indicate that there is significant energy transfer between the PPE backbone and the terminal porphyrin end group, and the PPE backbone works as an antenna transferring photo energy to ZnTPP terminal. The aggregation state of P-PPE in water was also investigated by UV–Vis and fluorescence studies.     

Synthesis and some properties of PVC-bound dimethylglyoxime complexes of Co(II), Ni(II), and Cu(II)

Poly(vinyl chloride) (PVC) has been reacted with dimethylglyoxime (DMG) in THF to form the PVC–DMG comples, which has been characterized by spectroscopic and elemental analyses. The latter indicate that there is one DMG moiety anchored on the PVC chain by displacing every 12th Cl atom in the chain. PVC–DMG has further been reacted with alcoholic solutions of Co(II), Ni(II), and Cu(II) to form the intensely colored PVC–DMG–M(II) complexes. The structures of these complexes have been analyzed by elemental and IR spectral analyses. The overall thermal stability of PVC–DMG–M(II) increases in the order: PVC < PVC–DMG–Cu(II) < PVC–DMG–Ni(II) < PVC–DMG–Co(II). The electrical conductivities are also significantly enhanced in the same order. The permittivities of these complexes are high relative to PVC at low frequency falling gradually with increasing frequency and the dielectric loss-frequency behavior is very broad.     

Synthesis, spectroscopic, and electrochemical properties of one novel hexanuclear Ru(II) polypyridyl complex

One novel hexapodal ligand 1,2,3,4,5,6-hexakis[(4,5-diazafluoren-9-yliminoxy)methyl]benzene (L) and corresponding Ru(II) polypyridyl complex [(bpy)₁₂(Ru^II)₆L](PF₆)₁₂ have been synthesized. Spectroscopic properties of the complex are investigated by UV–Vis absorption and fluorescence spectrometry. The complex shows metal-to-ligand charge transfer absorption at 438 nm and emission at 579 nm. Cyclic voltammetry of the complex comprises one Ru(II)-centered quasi-reversible oxidation at 1.31 V and three ligand-centered reductions.     

Alkoxo- and carboxylato-bridged hexanuclear copper(II) complex: Synthesis,structure and magnetic properties

Reaction of copper(II) nitrate trihydrate with N,N-dimethylethanolamine (dmea) and pivalic acid in methanol led to the hexanuclear copper(II) complex Cu₆(η¹:μ₂-C₄H₁₀NO)₄(η¹:η¹:μ₂-C₅H₉O₂)₄(η¹:μ₁-C₅H₉O₂)₂(μ₃-OH)₂ (1). The crystal structure of 1 indicates that hexametallic centers are bridged by the μ₃-alkoxo, dmea oxygens, and the μ₂-dicarboxylato oxygen atoms of pivalate ions. Furthermore, in the asymmetric unit, three types of copper ions have been found labeled as Cu₁, Cu₂ and Cu₃. The Cu₂ takes a distorted octahedral shape, whereas Cu₁ and Cu₃ adopt square pyramidal geometries. The complex 1 shows strong antiferromagnetic interactions through the oxo groups within the dimeric units (J = − 82.6 to − 25.8 cm^− 1) and weak antiferromagnetic couplings between the dimers (J = − 10.9 and 0.8 cm^− 1).     

Synthesis,crystal structure and photophysical properties of a novel Pt(II) complex with multi-functionalized cyclometalating ligand

A novel Pt(II) complex [(L)PtCl] (HL = 4-{p-[N-(4-(9-carbazole))butyl-N-phenyl] aniline}-6-phenyl-2,2′-bipyridine) has been synthesized and verified by ¹H NMR, elemental analysis and X-ray crystallography. The crystal (C₄₄H₃₅N₄ClPt, M_r = 850.30) belongs to monoclinic system, space group P2(1)/c, with a = 21.864(6), b = 9.306(3), c = 17.240(5) Å, β = 96.483(6)°, Z = 4, V = 3485.3(16) ų, D_C = 1.620 g/cm³, μ(Mo-Kα) = 4.141 mm^? 1, F(000) = 1688, R₁ = 0.0591, wR₂ = 0.0976. The coordinate geometry of the Pt atom is a distorted square planar configuration. The complex molecules are stacked by a weak π–π interaction in a head-to-tail fashion along the b axis to form 1D chain and the alternating 1D chains are packed to form the 2D lamellar system. The complex shows an intense metal-to-ligand charge transfer (¹MLCT) (dπ(Pt) → π*(L)) transitions (ε ～ 2 × 10⁴ dm³ mol^? 1 cm^? 1) at 448 nm in the UV–Vis absorption spectrum and a strong phosphorescence at 592 nm in CH₂Cl₂ solution at room temperature. An intramolecular energy transfer process from the carbazole unit to the arylamine-modified [(C^N^N)PtCl] emissive center exists in the complex.     

Synthesis,characterization of poly(allylamine)chelates with Cu(II), Co(II) and Ni(II)

Summary The parent polymer, poly(allylamine) as ligand polymer was employed to synthesize polychelates of heavy metal ions. The functional poly(allylamine) and its Ni(II), Co(II) and Cu(II) metal chelates were characterized by elemental analysis, FT-IR spectroscopy, TGA, and SEM. For the polychelates magnetic and conductivimetry studies were also carried out.     

Synthesis,structure and electrochemical properties of the cationic complex tris-(imidazolidine-1,10-phenanthroline)iron(II)

The complex [Fe^II(Imz-phen)₃](PF₆)₂, (Imz-phen = imidazolidine-[4,5-f]-1,10-phenanthroline) has been prepared and characterized using X-ray diffraction, UV–vis and IR spectroscopy, elemental analysis, fast atomic bombardment (FAB) mass spectrometry, and cyclic voltammetry. Its crystal lattice includes acetonitrile (π–π bound to phenanthroline), methanol, and water molecules. Scanning continuously between 1000 mV and 1650 mV in CH₃CN, a modified electrode that includes the iron (II) complex is obtained; after the 25th continuous cycle a stable film is formed that is electrocatalytically active in the reduction of sulfur oxoanions. When the electrocatalytic properties are evaluated in ethanol/water solution, the current achieved from the electroreduction of these sulfur species is linearly dependent on the respective concentrations, suggesting potential application in sulfite determination.