Syntheses,topological networks and properties of four complexes based on 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole ligand

Reactions of metal acetates with 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole (3-abpt) and co-ligands gave rise to four new complexes, namely [Zn₂(3-abpt)(beta)(DMF) (H₂O)₂]_n·nH₂O (1), [Zn(3-abpt)(ip)]_n·3nH₂O (2), [Zn(3-abpt)(ip)(H₂O)₂]_n·2nH₂O (3), and [Cu₂(3-abpt)₂(C₆H₅COO)₄(H₂O)₂]_n·2nH₂O (4) (ip = isophthalate, beta = 1,2,4,5-benzenetetracarboxylate). Compound 1 is a 3D coordination polymer with uncommon 3,4-connected (6².8)₂(6².8².10²) network. Compounds 2–4 are all 1D coordination polymers, which exhibit diversity structures. Compound 2 is a tubular-like chain, 3 is a ring-like network, and 4 is a zigzag chain. Their thermal stabilities and the photoluminescence of 1 have also been investigated.     

Three main group metal coordination polymers bearing imidazole-based dicarboxylates: Hydro(solvo)thermal syntheses, crystal structures and properties

Three coordination polymers [Pb(HMIDC)]_n (1), [Ba(H₂MIDC)₂]_n (2) and {[Mg(HMIDC)(H₂O)₂]·H₂O}_n (3) (H₃MIDC = 2-methyl-1H-imidazole-4,5-dicarboxylic acid) have been yielded under different hydro(solvo)thermal conditions. X-ray diffraction analysis reveals that compound 1 exhibits a 3-D framework constructed by 2-D networks joined by μ₄-HMIDC²⁻ bridges. Compound 2 also presents a 3-D structure, which is generated from 2-D layers pillared by 1-D chains along the c-axis. Compound 3 is a 1-D infinite chain and forms supramolecular layers through hydrogen bonds. The thermal and solid-state photoluminescence properties of polymers 1-3 have been determined as well. The theoretical predication of the methyl substituent effect of the ligand H₃MIDC has been investigated.     

Syntheses, crystal structures of a series of copper(II) complexes and their catalytic activities in the green oxidative coupling of 2,6-dimethylphenol

Three mixed-ligand Cu^II complexes bearing iminodiacetato (ida) and N-heterocyclic ligands, namely, [Cu₂(ida)₂(bbbm)(H₂O)₂] · H₂O (1), [Cu₂(ida)₂(btx)(H₂O)₂] · 2H₂O (2) and [Cu₂(ida)₂(pbbm)(H₂O)₂] · H₂O · 3CH₃OH (3) (bbbm = 1,1^′-(1,4-butanediyl)bis-1H-benzimidazole, btx = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene, pbbm = 1,1^′-(1,3-propanediyl)bis-1H-benzimidazole), in addition to three fcz-based Cu^II complexes, namely, {[Cu(fcz)₂(H₂O)₂] · 2NO₃}_n (4), {[Cu(fcz)₂(H₂O)] · SO₄ · DMF · 2CH₃OH · 2H₂O}_n (5) and {[Cu(fcz)₂Cl₂] · 2CH₃OH}_n (6) (fcz = 1-(2,4-difluorophenyl)-1,1-bis[(1H-1,2,4-triazol-l-yl) methyl]ethanol) have been prepared according to appropriate synthetic strategies with the aim of exploiting new and potent catalysts. Single crystal X-ray diffraction shows that 1 and 2 possess similar binuclear structures, 3 features a 2D pleated network, and 4 exhibits a 1D polymeric double-chain structure. Complexes 1-6 are tested as catalysts in the green catalysis process of the oxidative coupling of 2,6-dimethylphenol (DMP). Under the optimized reaction conditions, these complexes are catalytically active by showing high conversion of DMP and high selectivity of PPE. The preliminary study of the catalytic-structural correlations suggests that the coordination environment of the copper center have important influences on their catalytic activities.     

Synthesis, characterization and properties of some metal(II) 5-(nicotinamido)isophthalate complexes

Four new complexes, {[M(NAIP)(H₂O)₄]·2H₂O}_n (M = Co (1), M = Mn (2)), {[Zn(NAIP)]·0.5H₂O}_n (3) and {Cd(NAIP)(H₂O)₂]·1.5H₂O}_n (4) [H₂NAIP = 5-(nicotinamido)-isophthalic acid] have been prepared and structurally characterized. The ligand NAIP²⁻ exhibits different coordination modes and leads to the formation of various architectures. Complexes 1 and 2 show a one-dimensional (1D) zigzag chain, where hydrogen-bonding interactions further link these chains to a three dimensional (3D) supramolecular structure. For complex 3, a 3D coordination network with a four-coordinated Zn(II) and NAIP²⁻ as a SBU was observed. Complex 4 presents a three-connected 2-fold interpenetrated 3D network with a (10, 3)-b net topology. Their luminescent and magnetic properties have been investigated in the solid state.     

A zinc(II)-based two-dimensional MOF for sensitive and selective sensing of HIV-1 ds-DNA sequences

Coordination reaction of a known three-dimensional (3D) polymer precursor {Na₃[Na₉(Cbdcp)₆(H₂O)₁₈]}_n (A, Cbdcp = N-(4-carboxybenzyl)-(3,5-dicarboxyl)pyridinium) with Zn(NO₃)₂·6H₂O in H₂O or H₂O/DMF at 100 °C and in the presence of aspirin, 5-fluorouracil (5-FU) as modulators, trans-1,2-bis(4-pyridyl)ethylene (bpe) or 1,2-bis(4-pyridyl)ethane (bpea) as ancillary ligands afforded six novel Zn(II)-based metal-organic frameworks (MOFs), that is, {[Zn(Cbdcp)(H₂O)₃]·H₂O}_n (1, 1D zigzag chain), {[Zn(HCbdcp)₂]·H₂O}_n (2, 2D sheet), {[Zn(Cbdcp)(bpe)_1/2]·2H₂O}_n (3, 3D polymer), {[Zn(Cbdcp)(bpe)_1/2]·2H₂O}_n (4, 2D network), {[Zn(Cbdcp)(bpea)_1/2]·2H₂O}_n (5, 3D polymer) and {[Zn(Cbdcp)(bpea)_1/2]·2H₂O}_n (6, 2D network). Among them, compound 2 contains aromatic rings, positively charged pyridinium, Zn²⁺ cation centers and carboxylic acid groups lined up on the 2D sheet structure with a certain extended surface exposure. The unique structure of 2 facilitates effective association with carboxyfluorescein (FAM) labeled probe single stranded DNA (probe ss-DNA, delineates as P-DNA) to yield a P-DNA@2 system, and leads to fluorescence quenching of FAM via a photoinduced electron transfer process. The P-DNA@2 system is effective and reliable for the detection of human immunodeficiency virus 1 ds-DNA (HIV ds-DNA) sequences and capable of distinguishing complementary HIV ds-DNA from mismatched target sequences with the detection limit as low as 10 pM (S/N = 3).     

Crystal structures and properties of four coordination polymers constructed from flexible pamoic acid

Four novel coordination polymers constructed from flexible pamoic acid, namely [Co(pam)(4,4′-bipy)]_n·nH₂O (1), [Ni(pam)(4,4′-bipy)(H₂O)₂]_n·2nCH₃CN (2), [Cd(pam)(py)₂]_n·npy (3) and [Mn₂(pam)₂(py)₆(H₂O)₂]_n·2npy (4), (H₂pam = pamoic acid, 4,4′-bipy = 4,4′-bipyridine, py = pyridine), have been synthesized and characterized by elemental analysis, infrared spectra and X-ray crystallography. Complex 1 is a 2-D coordination polymer constructed from chelating bis-bidentate pam and 4,4′-bipyridine bridging ligands. Complex 2 is a 2-D coordination polymer assembled by bis-monodentate pam and 4,4′-bipyridine, where acetonitrile is filled in the rectangle channels. Both 2-D coordination polymers display undulated (4,4) grid layers as sql topology. Complex 3 displays a 1-D polymeric chain using chelating bis-bidentate pam as bridging ligand. Complex 4 exhibits an interesting bis-monodentate pam-Mn(II) 1-D polymeric chain, in which exist two-type six-coordinated manganese centers. Mn(1) is bound to four pyridine ligands, whereas Mn(2) is combined to two pyridine and two H₂O molecules. Their thermal stabilities have been investigated. Cadmium complex 3 displays strong green luminescence with emission maximum at 543 nm.     

Synthesis, structures, luminescent and magnetic properties of four coordination polymers with the flexible 1,3-phenylenediacetate ligands

Four coordination polymers, [Zn(pda)(bpy)(H₂O)]_n·nH₂O (1), [Cd(pda)(prz)(H₂O)]_n (2), [Co₃(μ₃-OH)₂(pda)₂(pyz)]_n·2nH₂O (3) and [Pr₂(pda)₃(H₂O)₂]_n (4) (H₂pda=1,3-phenylendiacetic acid, bpy=4,4′-bipyridine, prz=piperazine and pyz=pyrazine) have been hydrothermally synthesized and characterized. Complex 1 is a 1D wheel-like chain structure, which is further extended into a 3D metal-organic supramolecular framework by H-bonds and π-π stacking interactions. Complex 2 is a 1D ladder-like chain structure, which is also further extended into a 3D metal-organic supramolecular framework by H-bonds. Complex 3 possess a 2D sheet structure with infrequent two pairs of double-helix chains. Complex 4 features a 3D structure. Both 1 and 2 display strong blue fluorescent emission at room temperature. Magnetic susceptibility measurements of complexes 3 and 4 exhibit antiferromagnetic interactions between the nearest metal ions, with C=9.99 and 3.43 cm³ mol⁻¹ K, and θ=−23.9 and −46.3 K, respectively.     

Synthesis,crystal structures and spectroscopic studies of praseodymium(III) malonate complexes

Reactions of malonic acid (H₂mal) with PrCl₃·6H₂O afforded the known complex [Pr₂(mal)₃(H₂O)₆]_n (1), and compounds [Pr₂(mal)₃(H₂O)₆]_n·2nH₂O (2·2nH₂O), [PrCl(mal)(H₂O)₃]_n·0.5nH₂O (3·0.5nH₂O) and [Pr(mal)(Hmal)(H₂O)₃]_n·nH₂O (4·nH₂O) using various reaction ratios, reaction media (H₂O, MeOH) and pH values. Analogous reactions with CeCl₃·7H₂O afforded compounds [Ce₂(mal)₃(H₂O)₆]_n (5), [CeCl(mal)(H₂O)₃]_n·nH₂O (6·nH₂O) and [Ce(mal)(Hmal)(H₂O)₃]_n·nH₂O (7·nH₂O). Compounds 2·2nH₂O and 3·0.5nH₂O were characterized by X-ray crystallography, and 4–7 by microanalytical and spectroscopic data. The malonate(-2) ligand adopts three different coordination modes in the structures of 1–3, i.e., the μ₂-κO:κO′:κO″ and the μ₄-κ²O:κO′:κ²O″:κO? in 1 and 2 leading to a 3D network structure, and the μ₃-κ²O:κO′:κ²O″:κO? in 3 promoting an 1D structure. The thermal decomposition of 1 and 3·0.5nH₂O was monitored by TG/DTA and TG/DTG measurements. The structural features of 1–3 are discussed in terms of known malonato(-2) Ln^III and Ca^II complexes. The bioinorganic chemistry relevance of our results is discussed.     

A series of 2D lanthanide (III) coordination polymers constructed from 2-(pyridin-3-yl)-1H-imidazole-4,5-dicarboxylate

Reactions of 2-(pyridine-3-yl)-1H-4,5-imidazoledicarboxylic acid (H₃PyIDC) with a series of Ln(III) ions affords ten coordination polymers, namely, {[Ln(H₂PyIDC)(HPyIDC)(H₂O)₂]·H₂O}_n [Ln=Nd (1), Sm (2), Eu (3) and Gd (4)], {[Ln(HPyIDC)(H₂O)₃]·(H₂PyIDC)·H₂O}_n [Ln=Gd (5), Tb (6), Dy (7), Ho (8) and Er (9)], and {[Y₂(HPyIDC)₂(H₂O)₅]·(bpy)·(NO₃)₂·3H₂O}_n (10) (bpy=4,4′-bipyridine). They exhibit three types of networks: complexes 1-4 are isomorphous coordination networks containing neutral 2D metal-organic layers, while complexes 5-9 are isomorphous, which consist of cationic metal-organic layers and anionic organic layers, and complex 10 is a 2D network built up from 4-connected HPyIDC²⁻ anion and 4-connected Y(III) ions. In addition, thermogravimetric analyses and solid-state luminescent properties of the selected complexes are investigated. They exhibit intense, characteristic emissions in the visible region at room temperature.     

Monomer,dimer, tetramer and salt: Structural variations in Zn(II) complexes of 4,4′-bipyridine-N,N′-dioxide

Complexes of Zn^II salts with 4,4′-bipyridine-N,N′-dioxide (bpdo) have been prepared by solvathermal and solvent layering methods. Three complexes were obtained from ZnBr₂: 1 is a 2D coordination polymer [Zn₂Br₄(bpdo)₂]_n, (2) a discrete trimetallic molecule [Zn₃Br₆(H₂O)₂(bpdo)₄] and 3 a salt [ZnBr₄][Zn(H₂O)₅(bpdo)]. Complexes 2 and 3 contain Zn^II ions in both octahedral and tetrahedral coordination geometry. While in 2, these are covalently linked by bridging bpdo ligands forming zwitterionic trimetallic molecules, in 3 there is complete charge separation into [ZnBr₄]²⁻ anions and [Zn(H₂O)₅(bpdo)]²⁺ cations. When Zn(NCS)₂ is used as starting material, a 1D coordination polymer [Zn(H₂O)₂ (bpdo)(NCS)₂]_n is obtained.     

Syntheses and characterization of inorganic–organic hybrids with 4-(isonicotinamido)phthalate and some divalent metal centers

Four new inorganic–organic hybrid frameworks [Mn(L)(H₂O)₂]_n (1), {[Co(L)(H₂O)₃]·2H₂O·CH₃OH}_n (2), {[Zn(L)(H₂O)]·H₂O}_n (3) and [Cd(HL)₂]_n (4) [H₂L = 4-(isonicotinamido)phthalic acid] have been synthesized and characterized by single-crystal X-ray diffraction analysis. Complex 1 has three-dimensional (3D) structure and topology related to SrAl₂ (sra) with Schläfli symbol of (4²·6³·8). And 2 displays (3,3)-connected two-dimensional (2D) network with (4,8²) topology, while 3 exhibits a uninodal (3,3)-connected (6,3) 2D network, which is further linked by N–H?O hydrogen bonding interactions to give 3D structure with hms topology and Schläfli symbol of (6³)(6⁹·8). Complex 4 with partial deprotonated HL⁻ ligands also has a 2D network structure. In addition, the magnetic property of 1, nonlinear optical property of 3 and photoluminescence of 3 and 4 were investigated.     

Co(II), Mn(II) and Cu(II) complexes of fluoroquinolones: Synthesis, spectroscopical studies and biological evaluation against Trypanosoma cruzi

[MnCl₂(NOR)(H₂O)₂] (1), [MnCl₂(SPAR)(H₂O)₂] (2), [CoCl₂(NOR)(H₂O)₂] (3) [CoCl₂(SPAR)(H₂O)₂] (4), [CuCl₂(phen)(NOR)] (5) and [CuCl₂(phen)(SPAR)] (6) complexes with norfloxacin (NOR) and sparfloxacin (SPAR) were obtained from MnCl₂·4H₂O, CoCl₂·4H₂O and CuCl₂(phen). In all cases the NOR and SPAR coordinate in the neutral zwitterionic form. The electron paramagnetic resonance spectra of the Cu(II) complexes (5) and (6) in aqueous and DMSO solutions indicate mixture of mononuclear and binuclear complex. Complexes (1-6), together with the corresponding ligands were evaluated for their in vitro trypanocidal effect, against both bloodstream trypomastigotes and intracellular forms of Trypanosoma cruzi. SPAR and NOR were poorly effective upon T. cruzi, complexes (3) and (4) were active against intracellular forms of the parasite. The complexes (5) and (6) displayed a higher activity upon both bloodstream and intracellular forms. The potency of fluoroquinolones, specially those coordinated to Cu(II)-phen justify further trypanocidal screening assays with this compounds in vitro as well as upon experimental models of T. cruzi infection.     

Polynuclear Cu(II), Ni(II) and Cd(II) coordination compounds with bis(pyrimidin-2-yl)amine and dicyanamide

In this study the synthesis, crystal structure and characterization of three new transition metal polynuclear compounds with formula [Cu(dipm)(μ-dca)₂]_n(H₂O) (1), [Ni(dipm)(μ-dca)₂]_n(C₂H₆O)_1/2 (2) and [Cd(dipm)(μ-dca)₂]_n (3) (in which dipm = bis(pyrimidin-2-yl)amine and dca = dicyanamide) are reported. The isostructural compounds 1 and 2 contain a double-bridging end-to-end dca unit connecting two metal ions and a single bridging end-to-end dca unit between subsequent metals. Compound 3 exhibits only single bridging end-to-end dca units, oriented in three directions, giving rise to a 3D framework.     

Syntheses and characterization of different zinc(II) oxide nano-structures from direct thermal decomposition of 1D coordination polymers

Three zinc(II) nitrite coordination polymers, [Zn(4-bpdb)(NO₂)₂]_n (1), {[Zn(3-bpdb)(NO₂)]·0.5H₂O}_n (2) and [Zn(3-bpdh)(NO₂)₂]_n (3), 4-bpdb = 1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene, 3-bpdb = 1,4-bis(3-pyridyl)-2,3-diaza-1,3-butadiene and 3-bpdh = 2,5-bis(3-pyridyl)-3,4-diaza-2,4-hexadiene} were prepared and characterized by elemental analyses and IR spectroscopy. Compound 3 was structurally characterized by single-crystal X-ray diffraction and is one-dimensional polymer with coordination environments of distorted octahedral, ZnN₂O₄. The thermal stabilities of compounds 1–3 were studied by thermal gravimetric (TG) and differential thermal analyses (DTA). Direct calcination of the compounds 1–3 at 600 °C under air atmospheres yields different morphologies of nano-sized ZnO.     

Blue fluorescence of three metal-organic zinc polymers containing tetrazinc units and asymmetric ligand of btc

Three new zinc coordination polymers [Zn₂(btc)₂(H₂O)₂]_n·n[Zn(H₂O)₆] (1), [Zn₃(btc)₂(2,2′-bipy)₂(H₂O)₃]_n·2nH₂O (2) and [Zn₃(btc)₂(H₂O)₆]_n·nH₂O (3) (H₃btc=1,2,4-benzenetricarboxylic acid, 2,2′-bipy=2,2′-bipyridine) were obtained by the diffusion method and their crystal structures were determined by single-crystal X-ray diffraction. Compounds 1-3 have the similar tetrametallic unit [Zn₄(btc)₂] SBUs and these SBUs are further connected into stair-like structure, 2-D layer and 3-D framework for 1, 2 and 3, in which the btc³⁻ ligands adopt μ₃, μ₄ and μ₅ coordination modes, respectively. The title compounds show strong blue fluorescence, which may be assigned as π*→n transition of the ligand mixed with the ligand-to-metal change transfer (LMCT), indicating the fluorescence, indicates the title compounds may be good candidates for blue-light photoactive materials.     

Four distinctive 1-D lanthanide carboxylate coordination polymers: Synthesis,crystal structures and spectral properties

Four novel lanthanide coordination polymers [Pr(mal)(OH)(bipy) · 2H₂O]_n (1), {[Dy¹(SBA)₃(H₂O)₂][Dy²(SBA)₃(H₂O)₂] · 4H₂O}_n (2), {[Tb(OHnic)(Onic)(H₂O)₅ · (OHnicH)] · H₂O}_n (3) and {[Sm(OHnic)(Onic)(H₂O)₅ · (OHnicH)] · H₂O}_n (4) (Hmal = maleic acid, HSBA = 4-sulfobenzoic acid, OHnicH = 6-hydroxynicotinic acid and bipy = 2,2′-bipyridine) have been synthesized and determined by single crystal X-ray diffraction. Complex 1 is a 1-D helical chain with seven-coordinated praseodymium centers. Complex 2 forms 1-D chain-like molecular structure containing two crystallographically unique dysprosium centers, the Dy¹ center is seven-coordinated while Dy² is eight-coordinated. The isomorphous complexes 3 and 4 exhibit an unprecedented 1-D chain-like polymeric structure through hydroxyl oxygen atoms of bridging Onic²⁻ anions linking up the neighboring central ions, and there exist three types of 6-OHnicH ligands in the structural unit which is rare for lanthanide carboxylate complexes. The photophysical properties of these complexes were studied using ultraviolet absorption spectra, fluorescence excitation and emission spectra.     

Three novel lanthanide complexes with imidazole-4,5-dicarboxylate ligand: Hydrothermal syntheses, structural characterization, and properties

Three novel lanthanide complexes, namely, [Ce(Himdc)(H₂imdc)(H₂O)₃]·H₂O (1), {[Dy(Himdc)(Ox)_0.5(H₂O)₂]·H₂O}_n (2), and {[Nd(Himdc)(Ox)_0.5(H₂O)₂]·H₂O}_n (3) (H₃imdc = imidazole-4,5-dicarboxylic acid, Ox = oxalate), have been successfully prepared by the assembly of lanthanide ions and H₃imdc ligand under different synthetic conditions. All of the complexes have been characterized by means of elemental analysis, IR, TG analysis, luminescence spectroscopy as well as single-crystal X-ray diffraction analysis. The 3D supramolecular structure of 1 is constructed from 1D zig-zag chains through the hydrogen bonding interactions. Complex 2 possesses the chair-shaped secondary building units (SBUs) with Dy₆(Himdc)₄(Ox)₂ and meso-helical chains (P + M), resulting in a novel 2D structure based on the linkages of oxalate ligand. Complex 3 also presents 2D layer structure with uninodal 6-connected net topology, but crystallizes in the different space group and owns higher coordination number of the central metal atom than complex 2. The luminescence property of 2 is investigated in the solid state at room temperature.     

Co(II), Ni(II) and Zn(II)-orotate complexes with N-methylimidazole: Synthesis, crystal structures and antimicrobial activities

Three Co(II), Ni(II) and Zn(II) complexes of orotate with the N-methylimidazole ligand were synthesized and characterized by means of elemental and thermal analysis, magnetic susceptibilities, IR, UV-Vis spectroscopic and antimicrobial activity studies. The crystal structures of [Co(HOr)(H₂O)₂(Nmeim)₂]₃·H₂O (1), [Ni(HOr)(H₂O)₂(Nmeim)₂] (2) and [Zn(HOr)(H₂O)(Nmeim)₂] (3) were determined by the single crystal X-ray diffraction technique (H₃Or = orotic acid and Nmeim = N-methylimidazole). In complexes 1 and 2, the Co(II) and Ni(II) ions have distorted octahedral geometries with two Nmeim, one orotate and two aqua ligands. Complex 3 has a distorted trigonal bipyramidal geometry with two N-methylimidazole, one orotate and one aqua ligands. In the complexes, the orotate is coordinated to the metal(II) ions through the deprotonated nitrogen atom of the pyrimidine ring and the oxygen atom of the carboxylate group as a bidentate ligand. The complexes form a three-dimensional framework by hydrogen bonding, C-H?π and π?π stacking interactions. The MIC values of the complexes against selected microorganisms were determined to be in range 300-2400 μg/mL.     

All-cis-1,2,3,4,5,6-cyclohexanehexacarboxylate two-dimensional gadolinium(III) complexes: Synthesis,X-ray crystal structure and magnetic properties

The first gadolinium(III) complexes with the trideprotonated form of the 1,2,3,4,5,6-cyclohexanehexacarboxylic acid (H₃clhex³⁻) of formulae [Gd(H₃clhex)(H₂O)₄]_n·3nH₂O (1) and [Gd(H₃clhex)(H₂O)₄]_n·6nH₂O (2) have been prepared through the gel technique and their structures determined by single crystal X-ray diffraction. The structure of 1 is made up of 6³ honey-comb layers which are generated by [Gd(H₂O)₄]³⁺ cations and H₃clhex³⁻ anions acting as three-fold nodes and three-fold connectors, respectively. The structure of 2 consists of a [4⁴,6²] two-dimensional network extended in the ac plane where the H₃clhex⁻³ groups act as four-fold connectors and the [Gd(H₂O)₄]³⁺ units as four-fold nodes. Compound 1 crystallises in a non-centrosymmetric space group P2₁. Its absolute structure could be determined reliably, indicating the spontaneous resolution of a homochiral crystal and the freezing of one of the conformations of the all-cis H₃clhex⁻³ ligand. Compound 2 crystallises in the P2₁/n space group, the presence of an inversion centre making both conformations to occur. 1 and 2 are different solvates of the same system, the latter one synthesised under a higher pH value of the gel than the former. The investigation of the magnetic properties of 1 and 2 in the temperature range 1.9–300 K reveals a Curie law behaviour for the two compounds.     

Silver nitrate molecular species and coordination polymers with divergent supramolecular morphology constructed from hydrogen-bonding capable dipyridyl ligands

Solution phase reaction of silver nitrate with various hydrogen-bonding capable dipyridyl ligands has resulted in three 1-D coordination polymers and one discrete cationic species with diverse silver coordination spheres. [Ag(NO₃)(4,4′-dpk)]_n (1, 4,4′-dpk = 4,4′-dipyridylketone), {[Ag(4-bpmp)](NO₃) · 6H₂O} (2, 4-bpmp = bis(4-pyridylmethyl)piperazine) and {[Ag₂(NO₃)(3-bpmp)(H₂O)₂]NO₃}_n (3, 3-bpmp = bis(3-pyridylmethyl)piperazine) all display 1-D coordination polymer chain or ribbon motifs. Long-range Ag?O interactions and/or hydrogen-bonding promote the formation of different supramolecular aggregations such as a 2-D double layer slab in 1, a threefold interpenetrated 3-D diamondoid network in 2, and a 2-D single layer in 3. Compound 2 manifests “infinite” 1-D T(5)2 water molecule tapes within its incipient voids. {[Ag(2,4′-pmpp)₂](NO₃) · H₂O} (4, 2,4′-pmpp = 2-pyridyl(4′-methylpyridyl)piperazine) contains discrete cationic species connected by nitrate-mediated Ag?O interactions into a supramolecular 1-D zig-zag chain. Complexes 1 and 4 undergo weak blue–violet luminescence upon irradiation with ultraviolet light.