Synthesis,characterization, and fluorescence and cytotoxicity studies of a tetrarhenium molecular rectangle

An one-pot reaction of Re₂(CO)₁₀ with 4,4′-bipyridyl (4,4′-bpy) in refluxed 1-pentanol afforded the molecular rectangle, [(CO)₃Re(μ-OC₅H₁₁)₂Re(CO)₃]₂{μ-(4,4′-bpy)}₂ (I), in almost quantitative yield. The molecular rectangle, I, has been characterized spectroscopically and by X-ray crystal structure determination. Compound I exhibits fluorescence and is cytotoxic against cancer cell lines.     

Dinuclear based polymeric copper(II) complexes derived from a Schiff base ligand: effect of secondary bridging moieties on geometrical orientations and magnetic properties

[1 + 1] condensation of salicylaldehyde and 2-aminobenzenesulfonic acid led to the formation of the acyclic Schiff base o-[(o-hydroxyphenyl)methylideneamino]benzenesulfonic acid (H₂L) which, upon reaction with Cu(II) salts in the presence of triethylamine or 4,4′-bipyridine, formed a 2D polymeric species [Cu₂L₂]_n (1) via sulfonate bridge and a 1D polymeric complex [{Cu₂L₂(4,4′-bipy)}·DMF]_n (2) via 4,4′-bipyridine bridge, respectively. The copper cations sit on O₄N basal- or O₃N₂ facial-edge-sharing inverted square pyramidal environments in 1 or 2, respectively. In spite of their comparable compositions, the relative orientations of the metal polyhedra affect the magnetic properties of these polymers since 1, in contrast to 2, presents a strong exchange interaction of an antiferromagnetic nature.     

A novel helical chainlike nickel(II) coordination polymer containing 1D trigonal channels with water molecule guests

A novel 1D helical nickel coordination polymer, [Ni(TAU)₂(4,4′-bipy)]_n·2nH₂O (TAU = taurine, 4,4′-bipy = 4,4′-bipyridine), was synthesized and its crystal structure has been determined by X-ray diffraction. Each helix interlinks with six adjacent helices through extensive hydrogen bonds to form 3D supramolecular structure, in which 1D trigonal microporous channels filled with water guest molecules exist within the polymer coils. The framework remains intact on removal of guest water molecules which is proved by XPRD and TGA. Variable temperature magnetic susceptibility indicates weak anti-ferromagnetic interactions between the Ni(II) ions.     

Synthesis and spectroscopic properties of tetranuclear Re(I)(CO)4Cl complexes with tetracyanoethylene and tetracyanoquinodimethane as bridging ligands

The complexes {[Re^I(CO)₄Cl]₄(μ-TCNX)} with TCNX=tetracyanoethylene and tetracyanoquinodimethane were prepared and characterized spectroscopically. Both compounds show Re(I) to TCNX metal-to-ligand charge transfer absorptions in the near-infrared region.     

一种铜（I）的二维配合物（[CuCl（4,4′-bipy）]n）的合成、表征及晶体结构

利用水热法合成了一种CuI的二维层状聚合物：[CuCl（4,4′-bipy）]n,利用元素分析、FT-IR对其进行了表征,通过X-射线单晶衍射仪测定了其晶体结构。该晶体属于四方晶系,空间群I4（1）/acd,晶胞参数：a=14.1776（7）A, b=14.1776（7）A, c=38.490（3）A,α=90°,β=90°,γ=90°, V=7736.6（8）A^3, Z=32。     

Desulfurization and Denitrogenation Processes to Treat Diesel Using Mo(VI)-Bipyridine Catalysts

High efficiency was found for desulfurization and denitrogenation processes to treat diesel using either the hybrid material {[MoO₃(2,2′-bipy)][MoO₃(H₂O)]}_n or the octanuclear complex [Mo₈O₂₂(OH)₄(di-tBu-bipy)₄] (2,2′-bipy = 2,2′-bipyridine, di-tBu-bipy = 4,4′-di-tert-butyl-2,2′-bipyridine) as catalysts. These processes were employed in a single procedure to simultaneously remove sulfur (dibenzothiophene, 4-methyldibenzothiophene, and 4,6-dimethyldibenzothiophene) and nitrogen (indole and quinoline) compounds from diesel. A reaction time of two hours was sufficient to achieve at least 99.9 % S removal and 97 % N removal. Furthermore, the catalytic systems presented a high capacity to be reused/recycled for consecutive desulfurization/denitrogenation cycles.     

Crystal structure and novel magnetic property of a three-dimensional manganese(II)-μ-1,3-azido system

The synthesis, and crystal structure at room temperature of the three-dimensional manganese(II) complex with bridging 4,4′-bipyridine [Mn(4,4′-bipy) (N₃)₂]_n, in which the coordination mode of the azido ligand is end-to-end, are presented. The magnetic behavior for this compound is studied to show a weak antiferromagnetism to ferromagnetism transition at about 50 K, and is attributed to a canting phenomenon.     

Assembly and Property Study of a Keggin-Based Inorganic–Organic Supramolecular Compound

By introducing mixed organic ligands (pytz and 4,4′-bipy) into a Keggin POM system, a new Keggin POM-based supramolecular compound, [Cu₃(bipy)₄(pytz)₂(H₂O)₆][HSiMo₁₂O₄₀]₂·8H₂O (1) (pytz = 5-(pyridyl)tetrazolate, bipy = 4,4′-bipy) was hydrothermally synthesized and characterized by routine methods. Crystal structure analysis reveals that the title compound contains both right- and left-helical chains, and these helical chains are further connected together forming an interesting mesh network via sharing the [Cu₃(bipy)₄(pytz)₂(H₂O)₆] subunits. Finally, the 1D pillar-like chains link the mesh nets to construct a 3D supramolecular structure of 1. In addition, compound 1 shows good photocatalytic activity for the degradation of Rhodamine B dye.     

A new cyclometalated rhenium(I) complex

Reaction of Re(CO)₅Cl with 2-phenylbenzothiazole (HΦBT) afforded the cyclometalated Re(CO)₄(ΦBT) complex with the molecular structure of the obtained product confirmed by X-ray investigations. Re(CO)₄(ΦBT) shows intense, hardly dependent on environment, luminescence originating from the π–π* ΦBT intraligand electronic transition. The investigated Re(CO)₄(ΦBT) complex can be considered as a potentially applicable “triplet emitter” for OLED devices.     

Zinc(II)-Coordination Polymers Based on Isomeric Azo-Containing Anionic and Neutral Linkers

Four mixed-ligand coordination polymers, namely, [Zn(μ-3,3′-Cl₂abdc)(μ-4,4′-azobpy)]_n (1), [Zn(μ-4,4′-Cl₂abdc)(μ-3,3′-azobpy)_0.5(H₂O)]_n (2), [Zn₂(μ-4,4′-Cl₂abdc)(μ₄-4,4′-Cl₂abdc)_0.5(μ-OH)(μ-4,4′-azobpy)]_n (3) and {[Zn(H₂O)₄(μ-4,4′-azobpy)](4,4’-Cl₂abdc)}_n (4) (Cl₂abdc: dichloroazobenzenedicarboxylate and azobpy: azobispyridine) were synthesized with azo-group containing positional isomer anionic and neutral ligands in the presence of Zn(II) ion and characterized by elemental analysis, IR spectroscopy, single-crystal X-ray diffraction. X-ray results showed that the compounds displayed structural diversity depending on disposition of donor groups on ligands and solvent. Compounds 1 and 2 exhibited two-fold and five-fold interpenetrated 2D?→?2D structures, respectively, with the interchanging of positional isomer anionic and neutral ligands. Five-fold polycatenated 2D?→?3D structure was observed with the selection of 4,4′-Cl₂abdc and 4,4′-azobpy in 3. Although same ligands were used in the synthesis of 4 like compound 3, 1D structure of 4 was obtained with the use of DMF:water mixture and zinc nitrate. 4,4′-Cl₂abdc acted as a counter-ion in 4. Furthermore, topologic, thermal, optical and photoluminescence spectra of the compounds were studied in detail.

     

1D zigzag coordination polymer [Cu(tacn)(4,4′-bipy)]n·(ClO4)2n (tacn=1,4,7-triazacyclononane): structure,spectroscopic, and magnetic properties

A new one-dimensional coordination polymer, [Cu(tacn)(4,4^′-bipy)]_n ·(ClO₄)_2n (tacn = 1,4,7-triazacyclononane, 4,4^′-bipy = 4,4^′-bipyridine), has been synthesized and characterized by X-ray crystallography, elemental analysis, IR, electronic spectra, ESR and variable-temperature magnetic susceptibility (4–300 K). The Cu(II) ion is five-coordinated in a distorted square-pyramidal environment to three nitrogens of tacn and two nitrogens from two 4,4^′-bipy ligands. Each 4,4^′-bipy, in which two pyridine rings are slightly twisted, links two [Cu(tacn)]²⁺ units to form 1D zigzag chain. The magnetic behavior shows very weak interaction between metal ions.     

Two d10 coordination polymers based on 4,4′-(hexafluoroisopropylidene)diphthalic acid: Syntheses,structures and physical properties

Two novel coordination polymers, [Zn₂(FA)(4,4′-bipy)₂]·2H₂O (1) and Cd₂(FA)(2,2′-bipy) (2), (H₄FA = 4,4′-(hexafluoroisopropylidene)diphthalic acid, 4,4′-bipy = 4,4′-bipyridine, 2,2′-bipy = 2,2′-bipyridine), have been synthesized under hydrothermal conditions, and their structures were determined by single-crystal X-ray diffraction. Polymer 1 features an unusual three-dimensional (3D) network with (4 · 6² · 8³)(4² · 6² · 8²) topology. Polymer 2 has a complicated 3D framework and crystallizes in non-centrosymmetric space group (Fdd2) belonging to polar point group (C_2v), which displays a strong SHG response and ferroelectric properties. Moreover, the luminescent properties of 1 and 2 have also been investigated.     

Assembly of one 2D layer and two 3D pillared-layer structures derived from metal ions and 5-(pyridin-4-yl)isophthalic acid with or without pillars

Three new coordination polymers, [Mn(L)(H₂O)₂]₂·5H₂O (1), [Cu(L)(4,4′-bipy)]₂·H₂O (2) and [Pb(L)(4,4′-bipy)_0.5] (3) (H₂L = 5-(pyridin-4-yl)isophthalic acid; 4,4′-bipy = 4,4′-bipyridine) have been synthesized and characterized by IR, thermogravimetric analysis, X-ray powder diffraction and X-ray single crystal diffraction. Complex 1 shows a 2D layer structure which stacks with the other ones to form 1D channels to hold 1D water chains. Complex 2 displays a 3D + 3D → 3D polycatenation network. 3 shows a unique 2D + 2D → 3D polycatenation net in which each Pb center has a hemidirected coordination geometry due to the existence of “inert pair effect”. The thermal and luminescent properties of 1–3 were also examined.     

Rhenium(I) complexes with aliphatic Schiff bases appended to bio-active moieties

Novel facial tricarbonylrhenium(I) complexes, fac-[Re(urca)₂(CO)₃Cl] (1) and fac-[Re(bzta)(CO)₃Cl] (2) were isolated from the coordination reactions of 5-((5-hydroxypentylimino)methyl)uracil (urca) and 2-((5-hydroxypentylimino)methyl)benzothiazole (bzta) with [Re(CO)₅Cl], respectively. Spectral characterization of metal complexes 1 and 2 were supported by their X-ray crystal structures. DNA interactions were assessed via UV–Vis calf-thymus (CT)-DNA binding titrations and gel electrophoresis. Redox properties of the metal complexes were probed using voltammetry.     

Synthesis,crystal structure and third-order non-linear optical properties of two-dimensional supramolecular polymer [Co2(μ2-4,4′- bipy)2(μ2-be)2(be)2]n

Two-dimensional (2D) metal-organic supramolecular polymer [Co₂(μ₂-4,4′-bipy)₂(μ₂-be)₂(be)₂]_n 1 (4,4′-bipy = 4,4′-bipyridine, be = benzoate) has been synthesized by low-temperature solid-state reaction and characterized by single-crystal X-ray diffraction, elemental analyses, TGA, IR spectra and UV–visible spectra. The 2D structure is built from the linkage of secondary building units of binuclear [Co₂(μ₂-4,4′-bipy)₂(μ₂-be)₂(be)₂] clusters by a mixed connector of 4,4′-bipyridine and benzoate. The third-order non-linear optical (NLO) properties of the 1 were also investigated and they exhibit the reverse saturable absorption and self-defocusing performance with modulus of the hyperpolarizability (γ) 8.30 × 10⁻³⁰ esu for 1 in a 2.70 × 10⁻⁴ mol dm⁻³ DMF solution.     

A trimetallic supramolecular complex of osmium(II) and rhodium(III) displaying MLCT transitions in the near-IR

The mixed-metal supramolecule [{(tpy)OsCl(dpp)}₂RhCl₂](PF₆)₃ and the monometallic synthon [(tpy)OsCl(dpp)] (tpy = 2,2′:6′,2″-terpyridine, dpp = 2,3-bis(2-pyridyl)pyrazine) have been synthesized and studied by exploring redox and light absorbing properties. The complex [(tpy)OsCl(dpp)](PF₆) is synthesized by the reaction of [(tpy)OsCl₃] and dpp in ethylene glycol. The supramolecular complex [{(tpy)OsCl(dpp)}₂RhCl₂](PF₆)₃ is prepared by reaction of the monometallic synthon with RhCl₃ · 3H₂O in ethanol/water. Cyclic voltammetry shows an irreversible reduction for [{(tpy)OsCl(dpp)}₂RhCl₂](PF₆)₃ at −0.51 V (vs. Ag/AgCl) corresponding to the Rh^III/II/I couple. The Rh^III/II/I couple is anodic to the first dpp^0/− couple, predicting a lowest lying metal-to-metal charge transfer electronic excited state. Both the monometallic and trimetallic complexes absorb in the near-IR, with [{(tpy)OsCl(dpp)}₂RhCl₂](PF₆)₃ absorbing strongly throughout the 200–1000 nm region.     

Mono- and dinuclear rhenium(I) compounds with bidentate benzimidazole chelators

A mononuclear rhenium(I) complex, fac-[Re(CO)₃(bzch)Cl] (1), where bzch = 2-benzimidazole-4H-chromen-4-one, was isolated from the equimolar reaction between the Schiff base ligand 2-(2-aminophenyliminomethyl)-4H-chromen-4-one (H₂pch) and [Re(CO)₅Cl]. The 1:2 molar ratio reactions between [Re(CO)₅Cl] and N-(2-hydroxybenzylidene)-benzimidazole (Hbzp) afforded a dinuclear rhenium(I) compound, (μ-bzp)₂[Re(CO)₃]₂ (2). These new rhenium(I) compounds were characterized by NMR, UV–vis, IR, and emission spectroscopy, as well as conductance measurements and single crystal X-ray diffraction. The emission spectra for 1 in dichloromethane were well-resolved and could be deconvoluted into three main bands. The emission spectra for 2 were red-shifted by > 140 nm and markedly broadened relative to those of 1.     

Hydrothermal Crystal Growth,Structures and Thermal Properties of Co(II)-4,4′-bipyridine-Based Coordination Polymeric Materials

Hydrothermal synthetic parameters were studied and optimized for the preparation of new coordination polymeric materials based on Co(II) and 4,4′-bipy. A new polymeric compound, [Co₂(H₂O)₂(OH)₂(4,4′-bipy)₈](NO₃)₂·2(4,4′-bipy) 10(H₂O) (1), was prepared and structurally characterized by single crystal experiment. The framework of (1) is made up of two different one-dimensional substructures, i.e., the neutral chain A and positively charged chain B, both of which share the same nodes and node linkers. This is rarely found, especially from a one-pot crystal growth technique. Two other crystals were also identified, i.e., [Co(SO₄)(H₂O)₃(4,4′-bipy)]·2(H₂O), and K₂Co(H₂O)₆(SO₄)₂. The optimization of synthetic parameters apparently favors the formation of different polymeric structures, and this can be experimentally fine tuned. The influences of these parameters on phase formation, purity and crystal growth are discussed. The complicated thermogravimetric property of the new compound is also reported.     

A novel disubstituted Lindqvist-type polyoxomolybdate [Te2Mo4O19] supporting two organic vanadyl moieties: Synthesis, characterization, and crystal structure of {[V(2,2-bipy)2]2(4,4-bipy)[Te2Mo4O19]}

The first example of disubstituted Lindqvist-type polyoxomolybdate {[V(2,2-bipy)₂]₂(4,4-bipy)[Te₂Mo₄O₁₉]} has been synthesized hydrothermally and characterized by elemental analyses, XPS, IR, TG-DTA and X-ray single crystal diffraction. The structural analysis shows that the neutral molecular unit [V(2,2-bipy)₂]₂[Te₂Mo₄O₁₉] consists of a novel Lindqvist-type polyanion [Te₂Mo₄O₁₉]⁶⁻ supporting two vanadyl moieties [V(2,2-bipy)₂]³⁺, and such neutral molecules are joined together by π − π stacking interactions between the pyridine groups to form a two-dimensional grid-like network with non-coordinating “guest” 4,4-bipys encapsulated.     

Convergent synthesis of a heptaruthenium metallostar

A convergent synthesis of a heptaruthenium metallostar containing six {Ru(terpy)₂} and one {Ru(2,2′-bipy)₃} motif is described; the key intermediate is a 2,2′-bipy ligand bearing two {Ru(terpy)₂}-containing substituents which is prepared by the reaction of a coordinated ligand with a nucleophilic 2,2′-bipy derivative.