Syntheses,structures and luminescence of two cadmium entangled coordination polymers based on bis(imidazole) and biscarboxylate ligands

Two entangled coordination polymers [Cd₂(bib)(bdc)₂]_n (1) and [Cd₂(bib)(bda)₂]_n (2) were synthesized by the hydrothermal reaction (bib = 1,4-bis(2-methyl-imidazol-1-yl)butane, bdc = 1,2-benzenedicarboxylate, bda = 1,4-benzenediacetate). 1 exhibits an unusual 6-connected self-catenated 3D network based on Cd₂(COO)₂ dimer with the point symbol of (4⁴·6¹⁰·8). 2 exhibits a 3-fold interpenetrating 3D pcu network based on Cd₂(COO)₂ dimer. The different conformations of bib ligands (the anti–anti–anti conformation in 1 and gauche–anti–gauche conformation in 2) play the key role in the construction of different structures in 1 and 2. The luminescence and thermal stability were investigated.     

In situ attained CdII-coordination polymer with (3,4,9)-connected topology based on trinuclear CdII clusters

A new Cd^II-coordination polymer, namely, [Cd₃(nbtc)₂·4H₂O]_n (1), has been hydrothermally synthesized with in situ generated 5-nitrobenzene-1,2,3-tricarboxylate (nbtc^3?) ligand. Single-crystal X-ray diffraction study reveals that compound 1 is constructed from trinuclear Cd^II clusters and exhibits a previously unknown 2D (3,4,9)-connected (3.4²)(3².4³.5)(3⁶.4¹¹.5¹⁰.6⁸.8) topology as well as 3D H-bonding pillared architecture. In addition, the photoluminescent property and thermal stability of 1 were also discussed.     

Copper-assisted oxidative coupling of primary alcohol and hydrazone: A novel function model of galactose oxidase

Treatments of the MeOH, EtOH and PrOH solutions of 2-acetylpyridine, hydrazine and Cu^II salts (in molar ratio 2:3:2) afforded respectively the complexes, [Cu^II(HL)(Cl)](SO₃CF₃)H₂O (1), [Cu^II(MeL)(H₂O)](ClO₄)₂ (2) and [Cu^II(EtL)](Cl)](ClO₄) (3) (L = bis-(methyl, 2-pyridyl ketone hydrazonyl)methine), in which the ligands, HL, MeL and EtL are formed in situ from oxidative couplings of alcohols and hydrazones.     

Coordination assemblies of CdII/ZnII/CoII with the 3-(pyridin-4-yl) benzoate tecton: Structural diversity and properties

Three novel coordination polymers{[CdL₂(HL)(H₂O)]·(H₂O)}_n (1), [Zn₂(OH)L₃]_n (2) and [CoL₂(H₂O)]_n (3) have been hydrothermally synthesized from M(NO₃)₂·nH₂O (M^II = Cd^II, Zn^II and Co^II) and an unsymmetrical tecton 3-(pyridin-4-yl) benzoic acid (HL). All complexes show interesting structural patterns, namely, unprecedented 1D double-stranded supramolecular clasp for 1, novel (3,5,6)-connected helical tubular double layer for 2, 2-fold interpenetrating cds network for 3. The fluorescent and thermal properties of complexes 1, 2 and/or 3 have also been investigated.     

SOD mimic activity,DNA binding and in-vitro antibacterial studies of drug based copper(II) complexes

Square pyramidal complexes [Cu^II(PFL)(bpa)Cl]?5H₂O (1) and [Cu^II(LFL)(bpa)Cl]?5H₂O (2) have been synthesized and characterized. Compounds were checked for their in-vitro antimicrobial activity against two Gram^(+ ve) and three Gram^(–ve) bacterial species. Intrinsic binding constant (K_b) of complexes with CT DNA were determined using absorption titration. Viscosity measurement suggests that complexes bind with CT DNA through partial nonclassical intercalative mode. Superoxide dismutase (SOD) like activity of the complexes was also compared with previously reported compounds.     

Coordinate chloride and water-assisted assembly of novel 3D-cageworks of cadmium(II) complex with 4-[N,N-bis(2-cyanoethyl)]aminopyridine

Synthesis and structure of the cadmium(II) complex of [Cd^II(CEAP)₂(H₂O)(CH₃COO)Cl] {CEAP = 4-[N,N-bis(2-cyanoethyl)]aminopyridine} has been reported. The structure exhibits a novel 3D-cagework assembly with the assistance of the coordinated chloride anion and water molecule via forming multiple hydrogen bonds with the cyanoethyl arms of CEAP.     

Syntheses,structures and fluorescence studies of two new cadmium(II) pyridyl-diphosphonates

Two new cadmium diphosphonate complexes, namely, Cd₂(H₂O)₂[(C₅H₅N)CH₂C(OH)(PO₃)(PO₃H)]₂ 1 and Cd₂(H₂O)(Cl)[(C₅H₅N)CH₂C(OH)(PO₃)₂] 2, based on [1-hydroxy-2-(3-pyridyl)-ethylidene]-bis-[phosphonic acid] monosodium salt have been synthesized under hydrothermal reaction and characterized by single crystal X-ray diffraction. Both complexes show strong fluorescence emission in contrast to the free ligand, respectively, in solid state at ambient temperature.     

Syntheses,structures and luminescence of zinc and cadmium coordination polymers with bis(1,2,4-triazol-1-yl)butane and benzenedicarboxylate

The self-assembly reactions of the flexible ligand 1,4-bis(1,2,4-triazol-1-yl)butane (btb) and rigid ligand 1,4-benzenedicarboxylate (bdc) with Zn(II) or Cd(II) give two novel coordination polymers {[Zn(bdc)(btb)](H₂O)₅}_n (1) and {[Cd₂(bdc)₂(btb)(H₂O)₂](H₂O)₇}_n (2). Coordination polymer 1, a supramolecular isomer of [Zn₂(bdc)₂(btb)₂](H₂O)₂ [X.L. Wang, C. Qin, E.B. Wang, Z.M. Su, Chem. Eur. J. 12 (2006) 2680], is a special 2D (6,3) network, with six Zn(II) atoms at six corners and four bdc and two double btb at six edges. Coordination polymer 2 exhibits a distorted 3D cubic topology that is built from dimer Cd₂ units. The blue luminescent emission maxima at 420 and 439 nm for 1, 440 and 455 nm for 2 were observed in the solid state at room temperature.     

A new (3,4,7)-connected topology framework based on [Cd2(CO2)3O4N2] second building unit

A new 3D coordination polymer [Cd₂(L³)(BTC)(H₂O)] (1) (HL³ = 3,5-bis(pyridin-3-ylmethoxy)benzoic acid, H₃BTC = 1,3,5-benzenetricarboxylic acid), has been isolated under hydrothermal condition and characterized by single-crystal X-ray diffraction. Compound 1 is constructed from Cd₂-based second building units (SBUs) [Cd₂(CO₂)₃O₄N₂] and displays a 3D (3,4,7)-connected net with (4²·6)(4³·6³)(4⁵·6¹¹·8⁵) topology. In addition, the photoluminescent spectra indicate compound 1 may be a good candidate for blue-luminescent materials.     

H2mbpdc-funcationalized CdII6 cage captures protonated water clusters: Chloride-templated assembly and applications in recognition and separation

Assembly of CdCl₂ and 3,3′-dimethoxy-2,2′-bipyridine-6,6′-dicarboxylic acid (H₂mbpdc) under hydrothermal condition affords a chloride-centered discrete Cd^II₆ cage [Cd₆(mbpdc)₆Cl]·[H(H₂O)_14.5] (1), in which a cationic water cluster H⁺(H₂O)₁₀ is present. Our anion-templated assembly system exhibits exclusive encapsulation of Cl⁻ ion, and thus displays potentially applications in the separation of Cl⁻ ion with other halide ions.     

Photoinduced linkage isomerism of binuclear bis(pyrazole-3,5-dicarboxylato)-bridged {RuNO} centres

The two novel binuclear pyrazole-3,5-dicarboxylato-bridged {RuNO}⁶ complexes K₂[{Ru(NO)Cl}₂(μ-pzdc)₂] (1) and [{Ru(NO)(H₂O)}₂(μ-pzdc)₂]·4H₂O (2) (pzdc = pyrazole-3,5-dicarboxylate) were synthesized and characterized by elemental analysis, mass spectrometry and spectroscopic methods (NMR, UV–vis, IR). 2 was investigated by means of single-crystal X-ray diffraction analysis. On irradiation, in both 1 and 2 the existence of photoinduced long-lived metastable isonitrosyl states SI were detected by low-temperature infrared spectroscopy.     

Synthesis,crystal structure and water-induced reversible crystal-to-amorphous transformation property of [Co2(2,4-pydc)2(bpa)(H2O)6](H2O)2

The dinuclear Co^II coordination compound with empirical formula [Co₂(2,4-pydc)₂(bpa)(H₂O)₆](H₂O)₂ (1); bpa = 1,2-bis(2,4-pyridyl)ethane, 2,4-pydc = 2,4-pyridinedicarboxylate anion, has been synthesized and õcharacterized by elemental analysis, single crystal X-ray diffraction, IR and UV–vis spectra, TGA and XRPD. Compound 1 is a symmetry-related dinuclear compound consisting of two six coordinated cobalt atoms, one bpa ligand, two 2,4-pydc ligands and two lattice water molecules. Each Co^II ion is coordinated by one oxygen atom and one nitrogen atom from 2,4-pydc bidentate chelate ligand, one nitrogen atom of bpa bidentate bridging ligand and three water molecules, giving a distorted octahedral geometry with CoN₂O₄ chromophore. The crystal packing of this compound reveals a novel 3D supramolecular network, formed by hydrogen-bonding and C–H⋯π interactions. Investigations of the dynamic structural transformation behavior demonstrate that the title compound exhibits a solvent-induced reversible crystal-to-amorphous transformation with chromotropism when exposed to water vapor. This indicates that the dehydrated amorphous form, Co₂(2,4-pydc)₂(bpa)(H₂O)₂ (1A), may be utilized as an indicator for humidity.     

First hexanuclear manganese(II) μ6-Cl centered carboxylate anion: Synthesis,structure and magnetic properties

Reaction of manganese(II) polymer [Mn₅Cl(OH)(Piv)₈(MeCN)(HPiv)(H₂O)]_n (1, HPiv is pivalic acid) and 2-benzoylpyridine (L) in MeCN produces the ionic complex [Mn₃(Piv)₅L₂(MeCN)]⁺[Mn₆Cl(Piv)₁₂]⁻ · MeCN (3) containing the unusual hexanuclear {Mn₆(μ₆-Cl)} anion. An analogous anion was also observed in the complex [Mn₆Cl(Piv)₁₂]⁻(NEt₄)⁺ · 5MeCN (4) prepared by the reaction of the polymer [Mn(Piv)₂(EtOH)]_n (2) with NEt₄Cl in MeCN. Complexes 3 and 4 were characterized by the X-ray diffraction and magnetic susceptibility.     

Switching on the photochemical reactivity in heterodimetallic Os–Ru bipyridyl complexes containing a bis(bidentate) phosphine

For the first time the excited states of the RuP₂N₄ moiety belonging to a new heterodimetallic Os^II–Ru^II bipyridyl complex are successfully designed in order to introduce photochemical reactivity. This dramatic effect is achieved via the use of the sterically demanding bis(bidentate) phosphine cis, trans, cis-1,2,3,4-tetrakis(diphenylphosphino)cyclobutane (dppcb). Thus, the temperature dependence of the luminescence lifetimes ranging from 77 to 298 K for the novel homodimetallic species meso-(ΔΛ/ΛΔ)-[Os₂(dppcb)(bpy)₄](PF₆)₄ (1) and rac-(ΔΔ/ΛΛ)-[Os₂(dppcb)(bpy)₄](PF₆)₄ (2) clearly indicates that the d–d state responsible for photochemistry is not populated. By contrast, the analogous temperature dependence for the new heterodimetallic species ΔΛ/ΛΔ-[Os(bpy)₂(dppcb)Ru(bpy)₂](PF₆)₄ (3) and ΔΔ/ΛΛ-[Os(bpy)₂(dppcb)Ru(bpy)₂](PF₆)₄ (4) unequivocally shows that as a consequence of the population of the d–d state the photochemical reactivity is switched on. Since single crystal X-ray structure analyses are a major clue to the understanding of photophysical and photochemical properties, also the X-ray structures of 1–3 are given.     

Two-way synthesis of a double-lantern heterobimetallic complex [Pd(μ-OOCMe)4Co]2(μ-OOCMe)2Pd(py)2

The lantern complex Pd^II(μ-OOCMe)₄Co^II(NCMe) (1) was transformed into the pentanuclear double-lantern acetate-bridged heterobimetallic complex [Pd(μ-OOCMe)₄Co]₂(μ-OOCMe)₂Pd(py)₂ (py is pyridine) (2) by two routes: (i) reaction of 1 with pyridine and (ii) reaction of 1 with trans-Pd(py)₂(OOCMe)₂. Complex 2 × 3C₆H₆ was characterised by single-crystal X-ray diffraction, DTA-TG and magnetic susceptibility data.     

Controllable assembly of a 3-D metal–organic supramolecular framework with the inclusion of a well-resolved 1-D water morph

Two mixed-ligand metal–organic complexes [Cd₂(adipato)(phen)₂(NO₃)₂(H₂O)₂](H₂O)₆ (1) and {[Cd(adipato)(phen)](H₂O)₃}_n (2) have been synthesized upon the reaction of Cd(II) nitrate with 1,10-phenanthroline (phen) and adipate under similar conditions. For 1, the adipato-bridged dinuclear entities are extended into a 3-D supramolecular architecture via hydrogen bonds and π–π stacking. Interestingly, a well-resolved 1-D water morphology consisting of alternate cyclic water tetramer and hexamer is detected as the guests in each channel of this 3-D lattice. Whereas 2 represents a layered coordination polymer in which the Cd^II centers are interlinked by adipate dianions via different coordination modes.     

Six isostructural lanthanide-containing MOFs built on a semi-rigid tripodal organic ligand

By using a semi-rigid tripodal ligand 1,1′,1′′-(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)tripyridinium-4-olate) (L), six isomorphous lanthanum metal-organic frameworks (MOFs), namely, [Pr(L)₂(Cl)₂]·(Cl)(DMF)_0.5·(H₂O)·(1), [Nd(L)₂(Cl)₂]·(Cl)(2), [Tb(L)₂(Cl)₂]·(Cl)·(DMF)·(H₂O)(3), [Eu(L)₂(Cl)₂]·(Cl)(DMF)·(H₂O)(4), [La(L)₂(Cl)₂]·(Cl)(5), [Sm(L)₂(Cl)₂]·(Cl) (DMF)·(H₂O) (6), were obtained and characterized by single crystal X-ray diffraction, IR and elemental analysis. Six compounds are isostructural with Ln^3 + (Ln = Pr, Nd, Tb, Eu, La, Sm) and in which the Ln^3 + is considered as a 6-connecting node and the L ligand is a 3-connecting node to afford a (3,6)-connected 2D layer with kgd topology, which further stacks into 3D supramolecular networks through C-H^…O weak interactions. Luminescent properties of these lanthanide MOFs have also been assessed at ambient temperature, in which the Pr^3 +-1 and the La^3 +-5 are slightly blue-shifted with respect to the ligand. Series of sharp peaks characteristic of the Eu^3 +-4, the Tb^3 +-3 and Sm^3 + − 6 metal-centered luminescence appear. The Nd^3 +-2 has no emission.     

Synthesis and characterization of the zinc(II) complex of a bleomycin analogue: a unique polymeric 2-[((2-(4-imidazoyl)ethyl)amino)carbony]-6-[((2-amino-2-methylpropyl)amino)methyl]pyridine zinc(II) nitrate complex

The reaction of 2-[((2-(4-imidazoyl)ethyl)amino)carbonyl]-6-[((2-amino-2-methylpropyl)amino)methyl]pyridine (L) with Zn^II(NO₃)₂·6H₂O has afforded a novel one-dimensional polymeric Zn^II complex, (Zn^II(L)(NO₃)₂)_n (2). Complex 2 crystallizes in the space group P2₁/n with a=8.955(3), b=13.216(3), c=18.941(3) Å, β=103.39(2)°, V=2180.6(10) ų, and Z=4. The geometry of each Zn^II is approximately a trigonal bipyramid: three nitrogens and one oxygen of the amide group are coordinated to the zinc while the fifth site is occupied by the imidazole nitrogen of a neighboring unit.     

Initial use of 1,1′-oxalyldiimidazole for inorganic synthesis: Decomposition of the ligand as a means to the preparation of an imidazole- and oxalate(-2)-containing, 1D copper(II) complex

The use of 1,1′-oxalyldiimidazole, (im)COCO(im), for the synthesis of coordination complexes is explored for the first time. The [Cu₂(O₂CMe)₄(H₂O)₂]/(im)COCO(im) reaction system in 96% EtOH yields the new, 1D coordination polymer [Cu(ox)(Him)₂]_n (1), where Him is the neutral imidazole and ox^2? is the oxalate(-2) ligand. A mechanism for the hydrolytic decomposition of the ligand is proposed. Complex 1 comprises neutral, zigzag chains with the η¹:η¹:η¹:η¹:μ (2.1111 using Harris notation) ox^2? ligand bridging two neighboring Cu^II centers; two cis Him groups complete a Jahn–Teller distorted octahedral geometry at the metal. The dc, variable-temperature magnetic susceptibility data for the complex reveal antiferromagnetic Cu^II?Cu^II exchange interactions.     

Anion-directed assembly of two novel cadmium(II) complexes constructed by 2,2′-(1,4-butanediyl)bis(1H-benzimidazole) ligand

Depending on the different coordinated anions used, reaction of Cd(II) salt with 2,2′-(1,4-butanediyl)bis(1H-benzimidazole) results in the formation of two coordination polymers: a 1D chain {[Cd(H₂C4BIm)Cl₂] · (H₂C4BIm)}_n (1), and a 2D sheet [Cd(HC4BIm)(NCS)]_n (2) which features distorted 4.8² topology (H₂C4BIm = 2,2′-(1,4-butanediyl)bis(1H-benzimidazole)). The fluorescence properties for both the complexes have been studied.