A series of d transition metal coordination complexes: Structures and comparative study of surface electron behaviors (n = 9, 8, 7, 6, 5)

Ten transition metal coordination complexes [Cu₂(phen)(p-tpha)(μ-O)]_n1, [Cu(m-tpha)(imH)₂]_n2, [Ni(5-Haipa)₂(H₂O)₂]_n3, [Ni(phen)₂(H₂O)₂]·btc·[Ni(H₂O)₆]_0.5·9H₂O 4, [Co(2,5-pdc)(H₂O)₂]_n·nH₂O 5, [Co₂(2,5-pdc)₂(H₂O)₆]_n·2nH₂O 6, [Fe(2,5-Hpdc)₂(H₂O)₂]·H₂O 7, [Co(C₆H₄NO₂)₃]·H₂O 8, [Fe₂(μ₂-btec)(μ₂-H₂btec)(bipy)₂(H₂O)₂]_n9, [Mn(phen)(2,5-pdc)(H₂O)₂]·H₂O 10 (H₄btec = 1,2,4,5-benzenetetracarboxylic acid, phen = 1,10-phenanthroline, 2,5-H₂pdc = 2,5-pyridine-dicarboxylic acid, p-tpha = p-phthalic acid, m-tpha = m-phthalic acid, bipy = 2,2′-bipyridine, 5-H₂aipa = 5-aminoisophthalic acid, imH = imidazole, H₃btc = 1,3,5-benzenetricarboxylic acid) were synthesized through hydrothermal method. They were characterized by UV-Vis absorption spectra, single-crystal X-ray diffraction and surface photovoltage spectra (SPS). Structural analysis indicated that the complexes 1, 2, 3, 5, 6 and 9 were linked into infinite structures bridged by organic acid ligands. The other four complexes were molecular complexes and further connected to 2D or 3D structures by the hydrogen bonds. The SPS of complexes 1-10 indicate that there are positive response bands in the range of 300-800 nm showing different levels of photo-electric conversion properties. The intensity, position, shape and the number of the response bands in SPS are obviously different since the structure, species, valence, dⁿ electrons configuration and coordinated environment of the center metals are different. There are good relationships between SPS and UV-Vis spectra.     

Manganese(II) complexes with V-shaped sulfonyldibenzoate: The 3D structures with interpenetrated threefold or tetra-nuclear manganese(II) units

Five Mn^II-sdba coordination polymers with mono-, di-, tri-, tetra-nuclear cores based on the V-shaped 4,4′-dicarboxybiphenyl sulfone (H₂sdba) ligands: [Mn(sdba)(phen)₂(H₂O)]_n·3nH₂O (1), [Mn₂(sdba)₂(μ-H₂O)(py)₄]_n (2), [Mn₃(sdba)₂(Hsdba)₂(2,2′-bipy)₂]_n (3), [Mn₄(sdba)₄(4-mepy)₂(H₂O)₄]_n·2nH₂O (4) and [Mn₄(sdba)₄(bpp)₄(μ-H₂O)₂]_n·0.5nH₂O (5) (phen = 1,10-phenanthroline, 2,2′-bipy = 2,2′-bipyridine, 4-mepy = 4-picoline, bpp = 1,3-bi(pyridine-4-yl)propane) were hydrothermally synthesized and structurally characterized. The M-O-C metal clusters in above complexes act as SBUs, and the V-shaped sdba ligands link the SBUs to generate the novel frameworks. In complexes 1 and 3 their 1D chains are linked into the 2D planes through various hydrogen bonding. Complex 2 displays the 3D structure with interpenetrated threefold, while complexes 4 and 5 both exhibit the 3D structures with the tetra-nuclear Mn₄ units. The magnetic susceptibility studies in the 2-300 K range for these complexes reveal the existence of anti-ferromagnetic exchange interactions between the Mn^II ions.     

Syntheses, spectroscopies and structures of zinc complexes with malate

Reactions of zinc(II) ion with racemic malic acid (C₄H₆O₅ = H₃mal) result in the isolation of four new zinc(II) malato complexes: (NH₄)[Zn(R-H₂mal)₃] · H₂O (1), trans-[Zn(R-H₂mal)(S-H₂mal)(H₂O)₂] · 2H₂O (2), (NH₄)₂[Zn(R-Hmal)(S-Hmal)] · 2H₂O (3), and [Zn₂(R-Hmal)(S-Hmal)(H₂O)₄]_n · 2nH₂O (4). Three R-malic acids in 1 act as bidentate ligands via their alcoholic and the central carboxy groups with Zn(II) ion, leaving the terminal carboxylic acid groups free. The R- and S-malates of 2 coordinate in a bidentate manner with zinc ion in trans-form. In 3, Zn(II) ion is coordinated by R- and S-malates in a tridentate fashion via their alcoholic and two carboxy groups. Complex 4 forms a two-dimensional layered structure through the links of a new dimeric unit [Zn₂(R-Hmal)(S-Hmal)(H₂O)₄] with one of the oxygen atoms from the terminal carboxy group of malate ligand. The coordination of malates depends on pH variation, on Zn:malate ratio, and also on temperature. Tridentate chelation of malate in 3 is found between pH 4.5-9.0. The soluble monomeric species 1-3 have been investigated using ¹³C NMR spectra by long-time acquisition. The solution NMR spectra indicate that zinc malate complexes dissociate in H₂O (D₂O). Obvious downfield shifts of the central carboxy carbon atoms in 1-3 are observed compared with those of free malate, which indicate that these zinc malate complexes dissociate in aqueous solution.     

Syntheses, structures, and magnetic properties of 3d-4f heterometallic complexes constructed from pyrazole-bridged CuLn dinuclear units

A series of pyrazole-bridged heterometallic 3d-4f complexes, [CuDy(ipdc)₂(H₂O)₄] · (2H₂O)(H₃O⁺) (1) and [CuLn(pdc)(ipdc)(H₂O)₄] · H₃O⁺ (Ln = Ho (2), Er (3), Yb (4); H₃ipdc = 4-iodo-3,5-pyrazoledicarboxylic acid; H₃pdc = 3,5-pyrazoledicarboxylic acid), {[Cu₃Ln₄(ipdc)₆(H₂O)₁₆] · xH₂O}_n (Ln = Sm (5), x = 8.5; Ln = Eu (6), x = 7; Ln = Gd (7), Tb (8), x = 9), have been synthesized and structurally characterized. Ligand H₃ipdc was in situ obtained by iodination of ligand H₃pdc. Complexes 1-4 are pyrazole-bridged heterometallic dinuclear complexes, and 2-4 are isostructural. Complexes 5-8 are isostructural and comprised of an unusual infinite one-dimensional tape-like chain based on pyrazole-bridged heterometallic dinuclear units. The magnetic properties of compounds 1-4, 7 and 8 have been investigated through the magnetic measurement over the temperature range of 1.8-300 K.     

Hydrogen-bonded copper(II) and nickel(II) complexes and coordination polymeric structures containing reduced Schiff base ligands

Complexes [Cu(HSas)(H₂O)] · 2H₂O (H₃Sas = N-(2-hydroxybenzyl)-l-aspartic acid) (1), [Cu(HMeSglu)(H₂O)] · 2H₂O (H₃MeSglu = (N-(2-hydroxy-5-methylbenzyl)-l-glutamic acid) (2), [Cu₂(Smet)₂] (H₂Smet = (N-(2-hydroxybenzyl)-l-methionine) (3), [Ni(HSas)(H₂O)] (4), [Ni₂(Smet)₂(H₂O)₂] (5), and [Ni(HSapg)₂] (H₂Sapg = (N-(2-hydroxybenzyl)-l-aspargine) (6) have been synthesized and characterized by chemical and spectroscopic methods. Structural determination by single crystal X-ray diffraction studies revealed 1D coordination polymeric structures in 2 and 4, and hydrogen-bonded network structure in 5 and 6. In contrast to previously reported coordination compounds with similar ligands, the phenol remains protonated and bonded to the metal ions in 2 and 4, and also probably in 1. However, the phenolic group is non-bonded in 6.     

Coordination polymers and monomers based on new aminocarboxylate ligands: A cadmium(II) polymer containing dimeric aqua-bridged cadmium complex governed by polymeric chain

The synthesis and characterization of novel coordination polymers [Co(HCCB)(H₂O)₂]_n (1), [Zn(HCCB)(H₂O)₂]_n (2), {[Cd(HCCB)₂]·0.5[Cd(μ-H₂O)(H₂O)₄]₂}_n (3) and [Cu(HCCB)(H₂O)₂]_n (4) based on 3-(carboxymethylamino)-4-chlorobenzoic acid (H₃CCB) and mononuclear complexes [Cu(HBCCB)(H₂O)]·H₂O (5), [Co(HBCCB)(H₂O)]·H₂O (6), [Zn(HBCCB)(H₂O)] (7) and [Cd(HBCCB)(H₂O)] (8) containing 3-bis(carboxymethylamino)-4-chlorobenzoic acid (H₃BCCB) have been described. The compounds under investigation have been characterized by elemental analyses, spectral studies and structures of 1-3 and 5 determined crystallographically. Structural data of 1 and 2 revealed that the deprotonated HCCB²⁻ bridges metal centers leading to a double stranded 1D chain. On the other hand, the HCCB²⁻ coordinated thorough carboxylate oxygen and amino nitrogen in 3 to afford a 1D chain whose charge neutrality is maintained by inclusion of aqua-bridged dimer [{Cd(μ-H₂O)(H₂O)₄}₂]⁴⁺. Strong Cu?Cl interaction (2.754 Å) in 5 imposes a coordination geometry that is half-way between the square planar and square pyramidal. The H₃CCB, H₃BCCB and 1-3 and 5 are fluorescent at rt. Thermal studies (TG and DSC) on 1-3 suggested higher stability of 2 relative to 1 and 3 [ΔH_f (kcal/mol), ΔS_f = 152.17, 0.60, 1; 195.56: 0.86, 2; 69.33:0.36, 3].     

Construction of several d metal coordination polymers based on aromatic polycarboxylate and flexible triazole-based ligand

To investigate the effect of organic anions on the coordination frameworks, we synthesized five new complexes, namely, {[Zn₃(μ-OH₂)₂(btc)₂(btx)₃]·4H₂O}_n (1), [Zn(bdc)(btx)]_n (2), {[Ag₈(3,5-pydc)₄(btx)₄]·8H₂O}_n (3), [Ag(2,6-Hpydc)(btx)]_n (4) and [Cd₂(μ₂-OH₂)(2,6-pydc)₂(btx)]_n (5) (H₂bdc = 1,4-benzenedicarboxylic acid; H₃btc = 1,3,5-benzenetricarboxylate; 3,5-H₂pydc = pyridine-3,5-dicarboxylic acid; 2,6-H₂pydc = pyridine-2,6-dicarboxylic acid), which were obtained by the reactions of 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene (btx) as main ligand, and several aromatic polycarboxylate as organic anions with different d¹⁰ metal salts. Single crystal structure analysis shows that complexes 1, 3 and 5 possess 3D structures, 2 takes a 2D layer motif, and 4 displays a 1D chain structure. The distinct structures indicate that polycarboxylate anions with the diverse coordination modes and coordination groups can affect the topologies of metal-organic frameworks. In addition, the luminescence measurements reveal that the complexes 1, 2 and 5 exhibit strong fluorescent emissions in the solid state at room temperature.     

Syntheses and structure of heterobimetallic helical polymeric Mo-M(II) (M = Mn, Co, Zn, Cd or Ni) complexes using a flexidentate metalloligand

A series of heterobimetallic polymeric complexes of manganese, cobalt, zinc, cadmium and nickel, [M(Mo₂O₅L₂)(MeOH)₂(H₂O)₂]_n·nH₂O {M = Mn (2), n = 1, Co (3), n = 0, Zn (4), n = 1 and Cd (5), n = 1} and [Ni(Mo₂O₅L₂)(MeOH)(H₂O)₃]_n·2H₂O·MeOH (6) have been synthesized form the reaction of [{Na₄(H₂O)₄(μ-H₂O)₂} ⊂ (Mo₂O₅L₂)₂] (1) {LH₂ = 2-(3,5-di-tert-butyl-2-hydroxybenzylamino)acetic acid} with the corresponding metal salts. The complexes have been structurally characterized. The Complexes, 3 and 6 undergo thermal decomposition to afford mixed oxides of the type, MMoO₄·MoO₃ {M = Co or Ni}.     

A series of metal-organic frameworks constructed with 2,2′-bipyridine-3,3′-dicarboxylate: Syntheses, structures, and physical properties

To determine the influence of metal ion and the auxiliary ligand on the formation of metal-organic frameworks, six new coordination polymers, {[Mn₂(bpdc)(bpy)₃(H₂O)₂] · 2ClO₄ · H₂O}_n (1), {[Mn(bpdc)(dpe)] · CH₃OH · 2H₂O}_n (2), {[Cu(bpdc)(H₂O)₂]}_n (3), {[Zn(bpdc)(H₂O)₂]}_n (4), {[Cd(bpdc)(H₂O)₃] · 2H₂O}_n (5), and {[Co(bpdc)(H₂O)₃] · 0.5dpe · H₂O}_n (6) (H₂bpdc = 2,2′-bipyridine-3,3′-dicarboxylic acid, bpy = 2,2′-bipyridine, dpe = 1,2-di(4-pyridyl) ethylene), have been synthesized and characterized. Compound 1 forms 1D helical chain structure containing two unique Mn^II ions. In 2, the bridging ligand dpe links Mn-bpdc double zigzag chains to generate a layer possesses rectangular cavities. In 3, bpdc²⁻ ligand connects to three metal centers forming a 2D network. Different from the above compounds, 4 displays a 1D double-wavelike chain. Compound 5 features a helical chain. Compound 6 also displays a helical chain with guest molecule dpe existing in the structure. These diverse structures illustrate rational adjustment of metal ions and the second ligand is a good method for the further design of helical compounds with novel structures and properties. In addition, the magnetic properties of 2, 3 and 6, the thermal stabilities and photoluminescence properties of 4 and 5 were also studied.     

Novel topological nets of lanthanide metal-organic frameworks based on dicarboxylate ligands

Four novel topological nets of lanthanide metal-organic frameworks: [Sm₂(op)₃(H₂O)]_n (1), {Ln₂(op)₂(ox)(H₂O)₄] · H₂O}_n (Ln = La, 2; Sm, 3), {[La₂(mp)₂(ox)(H₂O)₄] · 2H₂O}_n (4), [La₂(op)₂(mp)(H₂O)₄]_n (5) (op = o-phthalate, mp = m-phthalate, and ox = oxalate), have been hydrothermally synthesized and characterized. Compound 1 exhibits novel (3,4,5,6)-connected five-nodal two-dimensional net, compound 2 and 3 show the (3,4)-connected V₂O₅ topologies, compound 4 has the (4,5)-connected topological net, and compound 5 shows the (4,5)-connected four-nodal three-dimensional network. Photoluminescent analyses of 1 and 3 show strong blue emission in the solid state at room temperature.     

Topological diversity in copper aromatic meta-dicarboxylate coordination polymers with bis(pyridylformyl)piperazine coligands

Hydrothermal synthesis has afforded divalent copper coordination polymers containing bis(4-pyridylformyl)piperazine (4-bpfp) tethers and aromatic meta-dicarboxylate ligands. {[Cu(ip)(4-bpfp)]·2H₂O}_n (1, ip = isophthalate) possesses a (4, 4) rectangular grid structure with an unusual ABCD stacking pattern along a 4₁ screw axis. Sterically bulky substituents in the 5-position of the isophthalate ligands reduced the coordination polymer dimensionality, with [Cu₂(tBuip)₂(4-bpfp)(H₂O)₂]_n (2, tBuip = 5-tert-butylisophthalate) and {[Cu(MeOip)(HMeOip)₂(4-bpfp)]·3H₂O}_n (3, MeOip = 5-methoxyisophthalate) displaying 1D polymeric ladder and chain motifs, respectively. Compound 3 possesses a rare twofold interpenetrated binodal supramolecular hms net with (6³)(6⁹8) topology. Longer meta-disposed acetate pendant arms induced a doubly interpenetrated 3D primitive cubic topology in {[Cu₂(1,3-phda)₂(H₂O)₂(4-bpfp)]}_n (4, 1,3-phda = 1,3-phenylenediacetate), which possesses antiferromagnetically coupled {Cu₂O₂} kernels (J = −6.14(8) cm⁻¹).     

A series of 1-D to 3-D metal-organic coordination architectures assembled with V-shaped bis(pyridyl)thiadiazole under co-ligand intervention

Six new coordination polymers based on V-shaped linkage 2,5-bis(4-pyridyl)-1,3,4-thiadiazole (bpt) and transition metal ions, [Co(bpt)(pm)_0.5(H₂O)]_n · 3nH₂O (1), [Cu₂(bpt)(pm)(H₂O)₄]_n (2), [Co(bpt)(pydc)]_n · 2nCHCl₃ · nH₂O (3), [Cu₂(bpt)(pydc)₂(H₂O)₂]_n (4), [Cu₂(bpt)(pydco)₂(H₂O)₂]_n · nH₂O (5) and [Cd(bpt)(pydco)]_n (6) (H₄pm = pyromellitic acid, H₂pydc = pyridine-2,6-dicarboxylic acid, H₂pydco = pyridine-2,6-dicarboxylic acid N-oxide), have been synthesized under the intervention of various polycarboxylate ligands. Complex 1 exhibits a 3-D 4-connected structure with 1-D nanosized open channels encapsulated lots of water molecules. Complex 2 represents a 2-D grid containing two types of rectangular windows. When pydc and pydco instead of pm, complexes 3 and 6 were obtained with highly undulated 2-D layers. The interlayers of 3 are filled with two kinds of solvent molecules, whereas 6 is a double-layered framework without free molecules. Complexes 4 and 5 consist of two distinct 1-D infinite chains held together to form different 2-D supramolecular networks. Importantly, bpt spacer shows changeful conformational geometries and generates complicated crystalline architectures with the introduction of polycarboxylate ligands. Additionally, thermal stability of complexes 1, 3 and 5, fluorescent properties of 6 and X-ray powder diffraction of 1 have also been investigated.     

N,N′-Bis(3-methoxysalicylidene)propane-1,2-diamine mononuclear 4f and heterodinuclear Cu-4f complexes: Synthesis, crystal structure and electrochemical properties

Reactions of H₂L [H₂L = N,N′-bis(3-methoxysalicylidene)propane-1,2-diamine] and Ln(NO₃)₃ · 6H₂O give rise to two different mononuclear 4f complexes, namely, {[(H₂L)La(NO₃)₃(MeOH)] · H₂O}_n (1) and [(H₂L)Nd(NO₃)₃] (2). Further additions of Cu(Ac)₂ · H₂O to the mononuclear 4f complexes yield expected heterodinuclear Cu-4f complexes [LCu(Me₂CO)Ln(NO₃)₃] (3, Ln = Nd; 4, Ln = Eu; 5, Ln = Dy). Complex 1 is a unique 1D polymeric chain structure, and 2 is one of the few structurally characterized discrete hexadentate salen-type mononuclear 4f complexes. Complexes 3-5 are similar to their analogues. However, they are prepared by a reversed synthetic route in contrast to their isomorphic complexes. Electrochemical behavior of heterodinuclear Cu-4f complexes 3-5 has been examined by cyclic voltammetry in acetonitrile. The redox potential of heterodinuclear Cu-4f complexes 3-5 shows significant anodic shift comparing to that of mononuclear copper complex (LCu). A tendency of anodic shift was observed in a sequence of 3 < 4 < 5. This results from the modulating effect of coordination geometry around Cu(II) ion on redox potential.     

Hydrothermal synthesis of two novel three-dimensional cobalt(II) metal-organic frameworks based on polycarboxylate and benzotriazole

The hydrothermal reactions of 1,4-H₂BDC or 1,4-H₂CDC, HBTA, with Co(NO₃)₂ · 6H₂O in basified solvent gave rise to two coordination polymers, Co₅(μ₃-OH)₂(1,4-BDC)₃(BTA)₂ (1), [Co(1,4-CDC)_0.5(BTA)] (2) (1,4-H₂BDC = 1,4-benzenedicarboxylic acid, 1,4-H₂CDC = 1,4-cyclohexanedicarboxylic acid, HBTA = benzotriazole) and characterized by elemental analysis, IR, single-crystal X-ray diffraction and variable-temperature magnetic measurements. Complex 1 crystallizes in the triclinic system, P space group; the structure determination reveals that 1 has a scarcely reported 8-connected 3D self-penetrating structure based on pentanuclear cobalt clusters. Complex 2 is monoclinic system, P2₁/c space group, and the X-ray structural analysis shows that 2 has a 3D infinite network with (4.6⁴.8)(4².6².8²) topology. Complex 1 exhibits moderately antiferromagnetic coupling, while complex 2 indicating strong spin-orbit coupling.     

Manganese(II) and zinc(II) compounds via amino acid derivatives: Effects of temperature and solvents

To investigate the influence of temperature and the ratios of solvents on the design and synthesis of metal-organic frameworks (MOFs), we have synthesized and structurally characterized a series of supramolecular assemblies based on different amino acid derivatives and nitrogen-containing heterocyclic ligands, namely [Mn(phen)₂(phth)(H₂O)]·4H₂O (1), [Mn(phen)₂(HL1)₂]·3.5H₂O (2), [Zn(bpp)₂(L-Me)₂] (3), and [Zn(bpp)(L-Me)₂] (4) (H₂phth = phthalic acid, H₂L¹ = phthalyl-l-valine, H₂L = (+)-N-tosyl-l-glutamic acid, phen = 1,10-phenanthroline, bpp = 1,3-bis(4-pyridyl)propane, and L-Me = C₁₂H₁₃NO₆S-CH₃). Compounds 1 and 2, which are assembled through noncovalent interactions, were obtained by controlling the temperature. In 1, π-π stacking and hydrogen-bonding interactions lead to stacking in a 3D supramolecular network, while in 2, π-π stacking interactions form 1D chains that extend along the c-axis. Depending on the solvents employed, compounds 3 and 4 could be generated, with a 1D bpp-connected Zn-bpp-Zn double chain that is further hydrogen-bonded into a 2D network that extends parallel to the ac plane in 3, and a single chain in 4.     

New examples of low-dimensional metal-pydco complexes: Syntheses, structures and magnetic properties

This work presents a systematic investigation on coordination chemistry of a novel pyridine-2,6-dicarboxylic acid N-oxide (pydco), and also reveals the significant function of supramolecular interactions in dominating the resultant crystalline nets. Assemblies of pydco with transition-metal ions under similar conditions yield a series of polymers in the absence/presence of the organonitrogen ligands {[Cu(pydco)(L)_0.5(H₂O)] · 2H₂O}_n (L = bipy (1), bpa (2) and bpe (3)), {[M(pydco)(bpp)(H₂O)] · 2H₂O}_n (M = Cu (4) and Ni (5)), [Ag₂(pydco)]_n (6) and [Ag₂Cu(pydco)₂]_n (7) (bipy = 4,4′-bipyridine, bpa = 1,2-bis(4-pyridyl)ethane, bpe = 1,2-bis(4-pyridyl)ethene, bpp = 1,3-bis(4-pyridyl)propane). 1-5 feature different structural characteristics, although they exhibit analogous chain networks. Remarkably, extended architectures are further constructed with the aid of weak interactions. Reaction of pydco with AgAc yields a 2-D polymer 6, which was reported in our recent Communication. A mixed-metal coordination polymer 7 was obtained by the self-assembly of AgAc, Cu(Ac)₂ · H₂O and pydco.In 7, two left- and right-hand helical chains are constructed by carboxylic groups of pydco and Cu centers, which are further connected by [AgCO₂]₂ cores into a 2-D network. Structural evolution under the co-ligand intervention in this series of compounds, as well as the general coordination rule of pydco, has been further discussed. Furthermore, variable temperature magnetic properties of 1, 3 and 7 are also studied. The magnetic measurements of 1 and 3 reveal the existence of weak antiferromagnetic interactions with J₁ = −4.59 cm⁻¹ and J₂ = −4.63 cm⁻¹, respectively. Whereas 7 displays weak ferromagnetic interactions with J₃ = 1.81 cm⁻¹.     

Tl benzene multicarboxylic acid coordination polymers: Structural, thermal and fluorescence studies

[Tl₃(μ-1,2,3-btc)]_n (1,2,3-H₃btc = 1,2,3-benzenetricarboxylic acid) (1), [Tl₂(μ-1,3,5-Hbtc)(H₂O)]_n (1,3,5-H₃btc = 1,3,5-benzenetricarboxylic acid) (2) and [Tl₄(μ-1,2,4,5-btc)]_n (1,2,4,5-H₄btc = 1,2,4,5-benzenetetracarboxylic acid) (3), three new Tl^I coordination polymers have been synthesized, characterized by elemental analysis and IR spectroscopy and their structures determined by single-crystal X-ray diffraction. The thermal stability of compounds 1-3 were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The single-crystal X-ray analysis of compounds 1-3 shows that the compounds are structurally diverse showing three-dimensional coordination polymers. The carboxylic groups of the ligands 1,2,3-btc³⁻, 1,3,5-Hbtc²⁻ and 1,2,4,5-btc⁴⁻ in the new Tl^I coordination polymers are not chelated and only act as bridging groups. In compounds 1-3, the lone pair of Tl(I) atoms is ‘active’ in the solid state and the coordination spheres are hemisphere type. Solution state luminescent spectra of compound 2 indicate intense fluorescent emissions at ca. 400 nm.     

Synthesis, crystal structures and properties of novel zinc(II) and cadmium(II) polymeric and cyclic bimetallic complexes with fluconazole and dicarboxylate co-ligands

Four new fluconazole-bridged zinc(II) and cadmium(II) complexes with dicarboxylate co-ligands, namely [Zn(HFlu)(TPA)]_n (1), {[Cd(HFlu)₂(TPA)]·2CH₃OH}_n (2), [Zn(HFlu)₂(Suc)(H₂O)₂]·H₂O (3), and [Cd(HFlu)₂(Suc)(H₂O)₂]·H₂O (4), have been synthesized and characterized by elemental analysis, IR, TG, and single-crystal X-ray diffraction (HFlu = 2-(2,4-difluorophenyl)-1,3-bis(1,2,4-triazol-1-yl)-propan-2-ol, H₂TPA = terephthalic acid, and H₂Suc = succinic acid). Complex 1 displays a 2-D corrugated network with common (4,4) topology, in which two types of grids constructed by two bridging TPA dianions and two HFlu ligands are found. Complex 2 shows an unusual (3,6) coordination layer consisting of alternative PMPM Cd-HFlu helical chains in which the Cd(II) nodes are also fixed by terephthalate dianions in a cis fashion. The isostructural complexes 3 and 4 have 20-membered dimeric macrocyclic motifs with the Zn···Zn and Cd···Cd distances of 11.258(2) and 11.528(2) Å, respectively. The fluorescence and thermal stability of complexes 1-4 have also been investigated.     

Divalent metal 1,3-phenylenediacetate coordination polymers with rigid or flexible dipyridyl tethers: Chains, layers, and interpenetrated networks

Hydrothermal synthesis has afforded four divalent metal 1,3-phenylenediacetate (1,3-phda) coordination polymers containing different dipyridyl-type ligands. {[Cu(1,3-phda)(dpa)(H₂O)]·H₂O}_n (1, dpa = 4,4′-dipyridylamine) exhibits a simple 2-D (4,4) rhomboid grid structure. {[Co(1,3-phda)(bpy)]·1.5H₂O}_n (2, bpy = 4,4′-bipyridine) also possesses a (4,4) layer structure, but with syn-syn bridged {Co₂(OCO)₂} dimeric kernels serving as 4-connected nodes. {[Co(H₂O)₄(3-bpmpH₂)](1,3-phda)₂·8H₂O}_n (3, 3-bpmp = bis(3-pyridylmethyl)piperazine) manifests cationic 1-D [Co(H₂O)₄(3-bpmpH₂)]_n⁴ⁿ⁺ chains linked into higher dimensionality by unligated 1,3-phda anions and curled tetrameric water molecule units. {[Ni(1,3-phda)(4-bpmp)(H₂O)₂]·2H₂O}_n (4, 4-bpmp = bis(4-pyridylmethyl)piperazine) has an underlying twofold interpenetrated 6⁵8 (cds) 3-D network topology. Variable temperature magnetic susceptibility studies revealed the presence of weak antiferromagnetic coupling and zero-field splitting (J = −1.65(4) cm⁻¹ and D = 30.9(7) cm⁻¹ with g = 2.20(1)) within the {Co₂(OCO)₂} dimers in 2.     

Synthesis, crystal structures and magnetic characterization of heterodinuclear CuGd and CuTb Schiff base complexes

Preparation, crystal structures and magnetic properties of new heterodinuclear Cu^IIGd^III (1) and Cu^IITb^III (2) complexes [CuLn(L)(NO₃)₂(H₂O)₃MeOH]NO₃·MeOH (where Ln = Gd, Tb) with the hexadentate Schiff-base compartmental ligand N,N′-bis(5-bromo-3-methoxysalicylidene)propylene-1,3-diamine (H₂L = C₁₉H₂₀N₂O₄Br₂) (0) have been described. Crystal structure analysis of 1 and 2 revealed that they are isostructural and form discrete dinuclear units with dihedral angle between the O1Cu1O2 and O1Gd1/Tb1O2 planes equal to 2.5(1)° and 2.6(1)°, respectively. The variable-temperature and variable-field magnetic measurements indicate that the metal centers in 1 and 2 are ferromagnetically coupled (J = 7.89 cm⁻¹ for 1). Crystal and molecular structure of the Schiff base ligand (0) has been also reported. The complex formation changes the conformation of Schiff base ligand molecule.