3D pillar-layered 4d–4f heterometallic coordination polymers based on pyridine-3,5-dicaboxylate and oxalate mixed ligands

Three 4d–4f heterometallic polymers, Ln₂Ag₂(Hpydc)₂(pydc)₂(ox) · 4H₂O (Ln = Nd (1), Eu (2) and Er (3); H₂Pydc = pyridine-3,5-dicarboxylic acid, H₂ox = oxalic acid), have been successfully synthesized under hydrothermal condition and structurally characterized. Single-crystal X-ray diffraction analyses reveal that three compounds are isomorphous and exhibit 3D pillar-layered coordination frameworks constructed from two-dimensional lanthanide-carboxylate layers and [Ag(pydc)]^? pillars. Furthermore, the luminescent property of compound 2 was studied.     

Construction of three isostructural 3d–4f microporous coordination frameworks based on mixed nicotinate and oxalate ligands

The self-assembly of nicotinic acid and sodium oxalate with mixed 3d–4f metal salts under hydrothermal conditions gave three isostructural 3D 3d–4f coordination polymers, [LnCu(nic)₂(ox)] · xH₂O [Ln = La, x = 1 (1); Ln = Eu, x = 2 (2); Ln = Gd, x = 2 (3)] [ox = oxalate, nic = nicotinate]. All three structures exhibit same unusual 3D microporous heterometallic coordination frameworks that are built up by rare tetranuclear Ln₂Cu₂ clusters and mixed ox and nic linkers. Furthermore, the luminescent property of complex 2 has also been investigated.     

A novel three-dimensional 3d–4f heterometallic coordination polymer with unique (3,4)-connected topology and helical units: Synthesis,crystal structure and photoluminescence property

One new three-dimensional 3d–4f heterometallic coordination polymer, namely, {[EuZn₂(imdc)₂(C₂O₄)_0.5(H₂O)₄]·2H₂O}_n (1) (H₃imdc = imidazole-4,5-dicarboxylic acid), has been successfully synthesized by the hydrothermal reactions of Eu₂O₃, Zn(NO₃)₂·6H₂O, H₃imdc, H₂C₂O₄·2H₂O and H₂O. Single-crystal X-ray diffraction analysis reveals that complex 1 possesses 3D heterometallic framework containing 2D layer based on L–Zn2–L (L = imdc) helical chains and L–EuZn1–L chains. Complex 1 exhibits unprecedented (3,4)-connected four-nodal topology with Schläfli symbol (6·7·8) (6·7·9) (6·7²·8²·10) (7·8²). Moreover, the photoluminescence property of 1 was investigated in the solid-state at room temperature.     

Three-dimensional 3d–4f heterometallic coordination polymer containing Sm2Mn4 clusters: Synthesis,crystal structure and properties

Heterometallic coordination polymers of the form {[SmMn₂(imdc)₂(OAc)(H₂O)]·2H₂O}_n (1) (H₃imdc = 4,5-imidazoledicarboxylic acid, HOAc = acetic acid) were hydrothermally synthesized and characterized by elemental analysis, IR, and single-crystal X-ray diffraction. The results reveal that 1 has a three-dimensional framework containing Sm₂Mn₄ clusters. The luminescence and magnetic properties of 1 were also investigated.     

Syntheses,structures and photoluminescence of Ln(III)–Cu(I) coordination polymers based on benzimidazole-5-carboxylate and oxalate ligands

Three novel Ln(III)–Cu(I) coordination polymers, namely [LnCu(Hbic)₃(ox)_0.5] [Ln = Sm (1), Dy (2), Hbic = benzimidazole-5-carboxylate, ox = oxalate] and [EuCu(Hbic)₂(ox)H₂O]·2H₂O (3) have been hydrothermally synthesized and stucturally characterized. Both complexes 1 and 2 display the same unusual 2D layer heterometallic coordination frameworks that are built up by dimeric [Ln₂(Hbic)₆] cores and oxalate ligands by sharing Cu(I) ions. Complex 3 represents 1D polymeric chain architecture constructed from Eu₂Cu₂ ring units and oxalate ligands. Furthermore, the luminescent property of complex 3 has also been investigated.     

Synthesis,characterization and luminescence of two unusual 4d–4f Ln–Ag coordination compounds

Two novel Ln–Ag coordination compounds with the formula [LnAg₂(IN)₄(OAC) · 5H₂O] · 2H₂O (Ln = Gd 1, Eu 2; HIN = isonicotinic acid; HOAC = acetic acid) have been synthesized under hydrothermal condition and characterized by single-crystal X-ray diffraction, thermal analysis, IR absorption spectroscopy, ultraviolet excitation and emission spectrum. The two compounds show isostructural architectures and exhibit an unusual 1-D structure, which is formed by the linkages of Ag–Ag.     

One-dimensional salen-type heterospin trimetallic (3d–4f–3d′) chain-like coordination polymers: Syntheses,crystal structures and magnetic properties

Three one-dimensional (1D) heterospin trimetallic chain-like polymers [{LCu(H₂O)}Ln(MeOH)(H₂O)₂{(μ-CN)₂Fe(CN)₄}]·2H₂O (1, Ln = La; 2, Ln = Nd; 3, Ln = Gd) were prepared by substitution of the nitrato ligands in [LCuLn] complexes with [Fe(CN)₆]^3? ions (H₂L = N,N′-bis(3-methoxysalicylidene)propane-1,2-diamine). Single-crystal X-ray diffraction analysis revealed that the methyl on the salen-type ligand impeded the connection between cyanide groups and Cu(II) ions efficiently. Consequently, three novel one-dimensional (1D) trimetallic chain-like polymers were obtained with the linker [Fe(CN)₆]^3? ions interacting only with the lanthanide ions. The magnetic investigation for 3 indicated a ferrimagnetic chain may form.     

A series of unusual three-dimensional 3d–4f (Ln/Cu/Cl/Br) cyanide heterometallic coordination polymers: Synthesis,crystal structure and magnetic properties

A series of unusual three-dimensional (3D) 3d–4f cyanide heterometallic coordination polymers (HCPs), namely [Ln_1.5Cu₃(ina)₃(ga)(CN)_1.5(X)(H₂O)] [Ln = Dy, X = Cl (1), Ln = Tb, X = Br (2), Ln = Dy, X = Br (3); ina = isonicotinic acid; ga = glycolic acid] have been synthesized via hydrothermal reaction and characterized by single crystal X-ray diffraction, elemental analyses, FT–IR spectroscopy, powder X-ray diffraction (PXRD) and thermogravimetric analyses (TGA). X-ray structural analysis reveals that HCPs 1 to 3 are constructed from the linkage between Ln–organic layer motifs and double-stranded cyano-containing Cu-inorganic ribbon motifs. In these complexes, the carboxyl group and hydroxyl group of H₂ga are all deprotonated and the coordinated ga ligands adopt a very interesting μ₃-kO:kO,O′:kO′,O″ coordination mode. Moreover, magnetic properties of HCP 1 were investigated.     

A novel 12-tungstovanadate and 3d–4d heterometallic complex hybrid compound [V1W12O40][VO2Ag(phen)3]2

A novel organic–inorganic hybrid compounds containing 12-tungstovanadate and 3d–4d heterometallic complex, [V₁W₁₂O₄₀][VO₂Ag(phen)₃]₂ (1), have been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction and IR analysis. The complex is an uncommon bisupporting polyoxometalate derivative in which the saturated Keggin type polyoxoanions are covalently linked by bimetallic complex [VO₂Ag(phen)₃]²⁺. The neighboring Ag⁺ and V⁵⁺ cations are bridged by the oxo atom forming heterometallic cations with the Ag–V distances of 3.556(2) Å in [VO₂Ag(phen)₃]²⁺ cations. Furthermore, the title compound shows good photocatalytic activity for reduction of Rhodamine B (RB) in a liquid–solid system.     

Synthesis of ferroelectric liquid crystalline polysiloxanes containing (S)-2-methylbutyl 4-alkyloxybiphenyl-4′-carboxylate and (2S, 3S)-2-chloro-3-methylpentyl 4-alkyloxybiphenyl-4′-carboxylate

The synthesis of side-chain liquid crystalline polysiloxanes containing (S)-2-methylbutyl-4-alkyloxybiphenyl and (2S, 3S)-2-chloro-3-methylpentyl 4-alkyloxybiphenyl-4-carboxylate moieties as mesogenic units and aliphatic spacers containing respectively three to eleven methylene units is presented. Differential scanning calorimetry, optical polarizing microscopy and X-ray diffraction measurements reveal chiral smectic mesomorphism for most of the obtained polymers. Two polysiloxanes that contain respectively three methylene units in their spacers exhibit an enantiotropic smectic A phase or no mesophase. Four polysiloxanes that contain respectively five, six and eleven methylene units in their spacers exhibit enantiotropic smectic A and chiral smectic C phases. The results seem to demonstrate that the tendency toward chiral smectic C mesomorphism increases with increasing spacer length. Incorporation of a chloro-containing chiral end group into the mesogenic core of a polymer will decrease the thermal stability of the mesophase formed.     

A novel 1-D mixed-valence cobalt coordination polymer bridged with (μ-Oalkoxo) and (μ-carboxylate) units: Synthesis,structure and properties

A novel one-dimensional helical mixed-valence cobalt coordination polymer (1) {[Co^IICo^III(HL)₂(OAc)]·CH₃OH·H₂O}_n, (H₃L = 2-ethyl-2-((2-hydroxynaphthalen-1-yl)methyleneamino)propane-1,3-diol) has been synthesized and characterized. Single-crystal X-ray diffraction analyses reveal that complex 1 crystallizes in the tetragonal I4(1)/a space group. It consists of a bimetallic Co^IICo^III(μ₂-O)₂ core, and the adjacent Co^II(2) centers are sequentially bridged by carboxylate groups in the syn–anti fashion, affording to a one-dimensional infinite helical chain along the c-axis. Adjacent chains are stacked via CH···π interactions to form the overall three-dimensional supramolecular networks. Magnetic and in vitro anticancer activities of the complex have been investigated in detail.     

A3Y2Ge3O12 (A = Ca,Mg): Two novel microwave dielectric ceramics with contrasting τf and Q × f

Two garnet-structured microwave dielectric ceramics of A₃Y₂Ge₃O₁₂ (A = Ca, Mg; called CYG and MYG, respectively) were synthesized. CYG was crystallized in a normal cubic garnet structure with Ca²⁺ fully occupying the dodecahedral (A) site, whereas MYG was an inverse garnet with mixed distribution of Mg²⁺/Y³⁺ at the A site. The difference in ionic occupation resulted in anomalies in microwave dielectric properties, with dielectric constant (ε_r) = 14.1, quality factor (Q × f) = 12,600 GHz and positive temperature coefficient of resonant frequency (τ_f) =120.5 ppm/°C for MYG ceramic and ε_r = 10.8, Q × f = 97,126 GHz and τ_f = −40.6 ppm/°C for CYG ceramic. The large deviations in measured ε_r from theoretical ε_th possibly resulted from the garnet structural constraints leading to ‘rattling’ Mg²⁺ and Y³⁺ in A site of MYG. Infrared reflectivity spectra analysis revealed ion polarization contributed mostly to the permittivity of both ceramics in microwave frequency ranges.     

A novel 3D silver(I) coordination polymer exhibiting unprecedented μ3- and μ4-bonding modes of 2-aminopyrazines

The unprecedented μ₃- and μ₄-bonding modes of NH₂pyz (NH₂pyz = 2-aminopyrazine) are observed for the first time in a novel 3D Ag(I) coordination polymer [Ag₇(NHpyz)₆(ClO₄)]_n (1) which was obtained by reaction of Ag₂O, NH₂pyz and NaClO₄ in H₂O/CH₃OH/NH₃ media under ultrasonic treatment. Compound 1 is a 3D framework with infinite 1D Ag belts incorporating diverse Ag···Ag interactions. Moreover, 1 exhibits photoluminescence maximized at 494 nm upon 300 nm excitation at room temperature, which may be mainly assigned to ligand-to-metal charge transfer (LMCT) mixed with metal-centered (d-s/d-p) transitions. Semiconducting behavior of 1 was also measured at room temperature with σ value of 6.78 × 10^?6 S cm^?1.     

Syntheses,structures and properties of a series of 3s–5d–4f mixed metal substituted sandwich-type arsenotungstates

A class of 3s–5d–4f mixed metal substituted sandwich-type arsenotungstates [H₂N(CH₃)₂]₈H₃[LnNa(H₂O)₄(OH)WO(H₂O) (B-α-AsW₉ O₃₃)₂]·8H₂O [Ln = La^III (1), Ce^III (2), Pr^III (3)] have been isolated from an aqueous solution reaction system (pH = 4) of Na₂WO₄·2H₂O, C₂H₇N·HCl, NaAsO₂ and Ln(NO₃)₃·6H₂O and structurally characterized by elemental analyses, IR spectra, UV spectra and single-crystal X-ray diffraction. It is the most prominent in 1–3 that the [LnNa(H₂O)₄(OH) WO(H₂O)(B-α-AsW₉O₃₃)₂]^11 − polyanion consists of two trivacant Keggin [B-α-AsW₉O₃₃]^9 − moieties linked by one [WO(H₂O)]^4 + group and a dimeric [LnNa(H₂O)₄(OH)]^3 + group resulting in the special 3s–5d–4f mixed metal substituted sandwich-type assembly. Interestingly, lanthanide and sodium ions simultaneously occupy the two positions located at the central belt of 1–3 with the site occupancy of 50% for each position. Moreover, the electrochemical and electrocatalytic properties of only 1 and 2 have been measured by cyclic voltammetry (CV) in 0.5 mol·L^− 1 Na₂SO₄ + H₂SO₄ aqueous solution. 1 and 2 illustrate electrocatalytic activities for the hydrogen peroxide reduction.     

Two novel cadmium(II) coordination polymers based on bis-functionalized ligand 4′-(4-carboxyphenyl)-2, 2′:6′, 2″-terpyridine

Two novel cadmium(II) coordination polymers [Cd(cptpy)₂]_n·nH₂O (1) with a 1D double chain structure and [Cd₂(cptpy)₂(ox)]_n·2.5nH₂O (2) with an interesting 3-connected uninodal six-fold interpenetrating ths network (Hcptpy = 4′-(4-carboxyphenyl)-2,2′:6′,2″-terpyridine, H₂ox = oxalic acid) have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR, single crystal X-ray diffraction and fluorescence spectra.     

Synthesis and mesomorphic behavior of poly[(2S, 3S)-(+)-2-chloro-3-methylpentyl 4′-(ω-vinyloxyalkyloxy)biphenyl-4-carboxylate]s with ethyl and propyl alkyl groups

Summary The synthesis and cationic polymerization of (2S, 3S)-(+)-2-chloro-3-methylpentyl 4-(2-vinyloxyethyloxy)biphenyl-4-carboxylate (15–2) and (2S, 3S)-(+)-2-chloro-3-methylpentyl 4-(3-vinyloxypropyloxy)biphenyl-4-carboxylate (15–3) are described. The mesomorphic behavior of the resulting polymers is discussed as a function of the molecular weight and spacer length. Based on the second and subsequent heating and cooling scans, poly(15–2)s exhibit an enantiotropic S_X (unidentified smectic) phase. Poly(15–2) with DP=4 is only crystalline. Poly(15–3)s show an enantiotropic cholesteric phase and an inverse monotropic S_X phase.     

Mesoporous CaO–ZrO2 nano-oxides: A novel solid base with high activity and stability

A new solid base, mesoporous CaO–ZrO₂ nano-oxides, was prepared via appropriate sol–gel process. It was found that such solid base showed high basicity and stability. Temperature programmed desorption of CO₂ confirmed that both weak and strong basic sites coexisted on the surface of CaO–ZrO₂ and the basicity could be modified by adjusting Ca/Zr molar ratio of the nano-oxides. The mesoporous CaO–ZrO₂ nano-oxides showed high thermal stability, since X-ray diffraction (XRD) and transmission electron microscopies (TEM) proved that the mesoporous network of this material preserved well even up to 700 °C. At the same time, XRD and Raman spectra indicated that Ca²⁺ incorporated into t-ZrO₂ lattice and the basic sites were firmly anchored to the substrate. As a result, this novel solid base showed remarkable activity and durability in the synthesis of dimethyl carbonate from methanol and propylene carbonate.     

A porous lanthanide metal–organic framework with luminescent property,nitrogen gas adsorption and high thermal stability

A novel lanthanide metal–organic framework, [Eu₂(BDC)₃(DMF)₂]·(DMF)_1.7(BDC = 1,3-benzenediacarboxylate) 1 has been synthesized under solvothermal condition and characterized by single-crystal X-ray structure determination, luminescent property, nitrogen gas adsorption, powder X-ray diffraction, IR, and TGA.     

A novel dirhenium(III) complex with bridging picolinate and methoxide ligands from the reaction between cis-Re2(μ-O2CCH3)2Cl4(H2O)2 and picolinic acid

The reaction of cis-Re₂(μ-O₂CCH₃)₂Cl₄(H₂O)₂ with picolinic acid (Hpic) affords either the diamagnetic, metal–metal bonded, dirhenium(III) complex Re₂(μ-OMe)(μ:η²-pic)(η²-pic)₃Cl (1) or the mononuclear rhenium(V) complex ReO(η²-pic)₂Cl (2), depending on whether mixed methanol/ethanol or acetone/ethanol solvent mixtures are used. The structures of 1 and 2 have been established by X-ray crystallography. Complex 1 is unusual in having a bridging methoxide and bridging picolinate ligand in an edge-sharing bioctahedral structure in which the Re–Re bond distance of 2.4588(4) Å is unusually short for what is a formal Re–Re double bond.