Synthesis, crystal structure, and magnetic properties of two 3d-4f heterometallic coordination polymers

Two new 4f-3d heterometallic coordination polymers, [Gd₂^IIICo^II(pydc)₃(ox)(H₂O)₄)·2H₂O] (1) and [Dy^IIICu^II(pydc)₂(ox)_1/2(H₂O)₂·H₂O] (2) (pydc = pyridine-2,5-dicarboxylate anion, ox = oxalate dianion) were successfully synthesized under hydrothermal condition. Structure and magnetism of the two coordination polymers were characterized by single crystal X-ray diffraction and Quantum Design (MPMS) SQUID magnetometer. In both compounds, metal centers were connected by double ligand bridges. In 1 the gadolinium ions were linked in sheets by OCO ligand bridges and these sheets were connected by separated cobalt coordination spheres to generate the overall 2-D structure. In 2 the dysprosium centers were constructed into one dimensional chain by OCO bridges from pydc ligand bridges and these chains were linked by oxalate bridges to form sheets and different sheets were connected by copper coordination planes. The copper centers in 2 were linked in chain by elongated OCO brides and the chains were connected by hydrogen bond to generate 3-D structure. Magnetic properties of the two complexes were investigated by variable temperature magnetic susceptibility. The magnetic data suggest that overall antiferromagnetic interactions are present in the two compounds.     

Three-dimensional 3d-4f heterometallic coordination polymers: synthesis, structures, and magnetic properties

Three new 3d-4f heterometallic coordination polymers, [Ln(2)(H(2)O)(4)M(2)(H(2)O)(2)(QA)(5)].nH(2)O (H(2)QA = quinolinic acid; Ln = Gd, M = Ni, n = 7 (1); Ln = Gd, M = Co, n = 6.5 (2); Ln = Dy, M = Co, n = 6.5 (3)), have been synthesized through hydrothermal pretreatment and cooling-down crystallization. These compounds possess the isostructural 3D frameworks with 1D chairlike channels along the c axis, which are occupied by noncoordinating water molecules. Crystal data: for 1, C(35)H(41)Gd(2)Ni(2)N(5)O(33), orthorhombic, space group Pna2(1), with a = 28.567(6) A, b = 14.498(3) A, c = 12.250(2) A, and Z = 4; for 2, C(35)H(40)Gd(2)Co(2)N(5)O(32.5), orthorhombic, space group Pna2(1), with a = 28.843(3) A, b = 14.4325(13) A, c = 12.2275(9) A, and Z = 4; for 3, C(35)H(40)Dy(2)Co(2)N(5)O(32.5), orthorhombic, space group Pna2(1), with a = 28.8471(14) A, b = 14.4534(10) A, c = 12.2520(7) A, and Z = 4. The magnetic behaviors for the three compounds have been investigated.     

Delicate crystal structure changes govern the magnetic properties of 1D coordination polymers based on 3d metal carboxylates

Homo- and heterometallic 1D coordination polymers of transition metals (Co II, Mn II, Zn II) have been synthesized by an in-situ ligand generation route. Carboxylato-based complexes [Co(PhCOO)2]n (1 a, 1 b), [Co(p-MePhCOO)2]n (2), [ZnMn(PhCOO)4]n (3), and [CoZn(PhCOO)4]n (4) (PhCOOH=benzoic acid, p-MePhCOOH=p-methylbenzoic acid) have been characterized by chemical analysis, single-crystal X-ray diffraction, and magnetization measurements. The new complexes 2 and 3 crystallize in orthorhombic space groups Pnab and Pcab respectively. Their crystal structures consist of zigzag chains, with alternating M(II) centers in octahedral and tetrahedral positions, which are similar to those of 1 a and 1 b. Compound 4 crystallizes in monoclinic space group P2 1/c and comprises zigzag chains of M II ions in a tetrahedral coordination environment. Magnetic investigations reveal the existence of antiferromagnetic interactions between magnetic centers in the heterometallic complexes 3 and 4, while ferromagnetic interactions operate in homometallic compounds (1 a, 1 b, and 2). Compound 1 b orders ferromagnetically at TC=3.7 K whereas 1 a does not show any magnetic ordering down to 330 mK and displays typical single-chain magnet (SCM) behavior with slowing down of magnetization relaxation below 0.6 K. Single-crystal measurements reveal that the system is easily magnetized in the chain direction for 1 a whereas the chain direction coincides with the hard magnetic axis in 1 b. Despite important similarities, small differences in the molecular and crystal structures of these two compounds lead to this dramatic change in properties.     

Yttrium-succinates coordination polymers: Hydrothermal synthesis, crystal structure and thermal decomposition

New polymeric yttrium-succinates, Y₂(C₄H₄O₄)₃(H₂O)₄·6H₂O and Y₂(C₄H₄O₄)₃(H₂O)₂, have been synthesized, and their structures (solved by single crystal XRD) are compared with that of Y₂(C₄H₄O₄)₃(H₂O)₂·H₂O. Three compounds were obtained as single phases, and their thermal behaviour is described.     

Two coordination polymers based on semicarbazone Schiff base and azide: synthesis,crystal structure,electrochemistry, magnetic properties and biological activity

[Mn(L)(μ_1,1–N₃)₂]_{2 n} [Mn(H₂O)₂(μ_1,1–N₃)₂] _n (1) and [Cd(HL)(μ_1,1–N₃)₂] _n (2) have been synthesized from HL (HL: pyridine-2-carbaldehyde semicarbazone) and azide ligands, characterized by FT-IR, UV–vis spectroscopy and X-ray crystallography. Single crystal X-ray diffraction revealed that 1 is a coordination polymer consisting of two infinite 1-D chains: chain A with [Mn(L)(μ_1,1–N₃)₂]_{2 n} and chain B with [Mn(H₂O)₂(μ_1,1–N₃)₂] _n . In both chains, Mn centers are connected via two double end-on (EO) azide bridges. 2 is a coordination polymer consisting of a 1-D infinite chain, where Cd centers are connected via two double EO azide bridges. The electrochemistry of HL, 1 and 2 were studied by cyclic voltammetry. Magnetic susceptibility measurements indicate bulk ferromagnetic coupling for 1 below 5?K. Antimicrobial activities of both compounds 1 and 2 were greater than HL, with the strongest effect for 2 consistent with its larger radius and electronegativity of Cd(II) ions.     

Two 1-D europium coordination polymers: synthesis,crystal structure and fluorescence

Two new complexes {[Eu(2, 4-DFBA)₃ · (H₂O)₂] · H₂O} _n (1) and [Eu(2-BrBA)₃ · H₂O] _n (2) (2, 4-DFBA = 2, 4-difluorobenzoate, 2-BrBA = 2-bromobenzoate) have been synthesized and characterized by single crystal X-ray diffraction. 1 has a 1-D chain structure, in which Eu(III) ions are bridged by single COO^? groups and a 2-D supramolecular network is formed by hydrogen bond interactions. In 1, each Eu(III) is eight-coordinate with six oxygens from four 2,4-DFBA ligands and two waters. 2 has a 1-D chain structure, in which Eu(III) ions are bridged by bridging-chelating-bridging COO^? groups. In 2, each Eu(III) ion is nine-coordinate with eight oxygens from five 2-BrBA ligands and one water. The two complexes exhibit intense luminescence at room temperature. The ⁵D₀ → ⁷F _j (j = 0–4) transition emissions of Eu(III) have been observed.     

Syntheses,crystal structures,and magnetic properties of 1-D coordination polymers

Three coordination polymers of Robson-type macrocycles, {[Cu₄L¹(4,4′-bipy)₂]·4ClO₄·H₂O}_∞ (1), {[Cu₄L²(4,4′-bipy)₄]·2CH₃CN·4ClO₄·2H₂O}_∞ (2), and {[Zn₂L²(4,4′-bipy)₂]·(ClO₄)₂}_∞ (3) (where H₂L¹ and H₂L² are the [2?+?2] condensation products of 1,3-diaminopropane with 2,6-diformyl-4-methylphenol and 2,6-diformyl-4-fluorophenol, respectively), have been synthesized and characterized. Magnetic susceptibility was measured for 1 and 2 from 2 to 300?K. The optimized magnetic data were J?=?–368.5?cm^?1, J′?=?40.5?cm^?1 with R?=?1.69?×?10^?6 for 1 and J?=?–291.22?cm^?1, J′?=?83.74?cm^?1, ρ = 0.00168 with R?=?1.8?×?10^?11 for 2, respectively. The data reveal strong antiferromagnetic interactions between two Cu(II) ions in the macrocyclic unit and ferromagnetic interaction between the Cu(II) ions in two adjacent macrocyclic units for 1 and 2.     

A novel sheet 4f-3d mixed-metal pyridine dicarboxylate: synthesis, structure, photophysical properties and its transformation to a perovskite oxide

The synthesis, characterization and photophysical properties of a 4f-3d mixed metal compound, Gd(H2O)3Co[C5N1H3(COO)2]3, are described; the structure is unique, consisting of sheets with large pores (ca. 7 Angstroms diameter) in the sheets and transforms to a perovskite oxide at moderate temperatures.     

1,2,4,5-benzenetetracarboxylate- and 2,2'-bipyrimidine-containing cobalt(II) coordination polymers: preparation, crystal structure, and magnetic properties

Three new mixed-ligand cobalt(II) complexes of formula [Co2(H2O)6(bta)(bpym)]n.4nH2O (1), [Co2(H2O)2(bta)(bpym)]n (2), and [Co2(H2O)4(bta)(bpym)]n.2nH2O ( 3) (bpym = 2,2'-bipyrimidine and H 4bta = 1,2,4,5-benzenetretracaboxylic acid) have been synthesized and characterized by single crystal X-ray diffraction. 1 is a chain compound of mer-triaquacobalt(II) units which are linked through regular alternating bis-bidentate bpym and bis-monodentate bta groups. 2 and 3 are three-dimensional compounds where aquacobalt(II) ( 2) and cis-diaquacobalt(II) ( 3) entities are linked by bis-bidentate bpym ( 2 and 3) and tetrakis- ( 2 and 3) and octakis-monodentate ( 2) bta ligands. The cobalt atoms in 1- 3 exhibit somewhat distorted octahedral surroundings. Two bpym-nitrogen atoms ( 1- 3) and either two bta-oxygens ( 2) or one bta-oxygen and a water molecule ( 1 and 3) build the equatorial plane, whereas the axial positions are filled either by two water molecules ( 1) or by a bta-oxygen atom and a water molecule ( 2 and 3). The values of the cobalt-cobalt separation across the bridging bpym vary in the range 5.684(2)-5.7752(7) A, whereas those through the bta bridge cover the ranges 5.288(2)-5.7503(5) A (across the anti-syn carboxylate) and 7.715(3)-11.387(1) A (across the phenyl ring). The magnetic properties of 1- 3 have been investigated in the temperature range 1.9-290 K. They are all typical of an overall antiferromagnetic coupling with the maxima of the magnetic susceptibility at 14.5 ( 1) and 11.5 K ( 2 and 3). Although exchange pathways through bis-bidentate bpym and carboxylate-bta in different coordination modes are involved in 1- 3, their magnetic behavior is practically governed by that across the bpym bridge, the magnitude of the exchange coupling being J = -5.59(2) ( 1), -4.41(2) ( 2), and -4.49(2) ( 3) with the Hamiltonian H = - JS 1 S 2.     

Synthesis,crystal structures,and magnetic properties of three isomorphous helical coordination polymers

Three isomorphous coordination polymers of general formula {[M(H₂bna)·(DMF)₂·(H₂O)₂]·DMF}_n (M = Co for 1, Mn for 2, Ni for 3, respectively, where H₄bna = 2,2′-dihydroxy-[1,1′]-binaphthalene-3,3′-dicarboxylate) were synthesized under solvothermal conditions and characterized by FTIR, single crystal X-ray diffraction, thermogravimetric analysis, and X-ray power diffraction analysis. All three polymers crystallize in the same monoclinic space group P2₁/n. The complexes are assembled into 1D helical chains, and each adjacent helical chain of the same chirality is further connected to form a chiral layer by hydrogen bond interactions. The layers are packed in alternating left-(M) and right-handed (P) chirality arrays. Magnetic studies reveal the presence of antiferromagnetic coupling interactions in complexes 1 and 2.     

A series of novel metal-ferrocenedicarboxylate coordination polymers: crystal structures, magnetic and luminescence properties

Novel two-dimensional layered lanthanide(III)-ferrocenedicarboxylate coordination polymers {[M(η²-O₂CFcCO₂-η²)(μ₂-η²-O₂CFcCO₂-η²-μ₂)_0.5(H₂O)₂]·mH₂O}_n (Fc=(η⁵-C₅H₄)Fe(η⁵-C₅H₄), M=Tb³⁺, m=2, 1; M=Eu³⁺, m=2, 2; M=Y³⁺, m=1, 3) with trapezium-shaped units and one-dimensional wave-shaped Cd(II)-ferrocenedicarboxylate polymer {[Cd(η²-O₂CFcCO₂-η²)(H₂O)₃]·4H₂O}_n (4) have been prepared and structurally characterized by single crystal diffraction. In polymers 1-3, each central metal ion (Tb(III), or Eu(III) or Y(III)) is located in a pseudo-capped-tetragonal prism coordination geometry, and ferrocenedicarboxylate anion ligands have two coordination modes (bidentate-chelating mode and tridentate-bridging mode). The magnetic behaviors for 1 and 2 are studied in the temperature range of 5.0-300 K. The results show that the paramagnetic behavior of 2 is mainly due to the effective spin-orbital coupling between the ground and excited states through the Zeeman perturbation, and the weak magnetic interaction between Eu³⁺ centers can be observed. In addition, compared with sodium ferrocenedicarboxylate, the fluorescent intensities of the polymers 1-4 are enhanced in the solid state.     

Heterotrimetallic oxalato-bridged ReIV2MII complexes (M=Mn, Co, Ni, Cu): synthesis, crystal structure, and magnetic properties

The use of the (NBu4)2[ReIVCl4(ox)] mononuclear species as a ligand toward divalent first row transition metal ions in the presence of imidazole affords the new trinuclear compounds of formula (NBu4)2[{ReIVCl4(mu-ox)}2MII(Him)2] [NBu4+=tetra-n-butylammonium cation, ox=oxalate dianion, Him=imidazole; M=Mn (1), Co (2), Ni (3), Cu (4)] whose preparation, crystal structures, and magnetic properties are reported. 1-4 are isostructural complexes which are made up of discrete trinuclear [{ReIVCl4(mu-ox)}2MII(Him)2]2- anions and bulky NBu4+ cations. The Re and M atoms exhibit somewhat distorted octahedral surroundings which are built by four chloro and two oxalate oxygens (Re) and two imidazole nitrogen and four oxalate oxygen atoms (M), the central M atom being linked to the two peripheral Re atoms through bis-bidentate oxalate. The values of the Re...M separation across bridging oxalate vary in the range 5.646(2) (M=Ni) to 5.794(2) A (M=Mn). Magnetic susceptibility measurements on polycrystalline samples of 1-4 in the temperature range 1.9-300 K show the occurrence of significant intramolecular antiferro- (1) and ferromagnetic (2-4) interactions. The nature and magnitude of the magnetic coupling in 1-4 are qualitatively understood through orbital symmetry considerations.     

3d and 4d coordination complexes and coordination polymers involving electroactive tetrathiafulvalene containing ligands

The “through bond” approach has been recently developed to increase the interaction between the mobile π and localized d electrons in multifunctional molecular materials involving tetrathiafulvalene-based ligands. This article reviews the 3d and 4d coordination complexes and polymers elaborated from a library of tetrathiafulvalene derivatives containing ligands obtained recently in our group. The different synthetic ways of the complexes are highlighted as well as their chemical and physical properties.     

Coordination polymer gels: synthesis, structure and mechanical properties of amorphous coordination polymers

The synthesis and mechanical properties of a new class of coordination polymer based materials, amorphous coordination polymer sol-gels and xerogels, is presented.     

Synthesis,structure, photoluminescence and magnetic properties of lanthanide-pyridine-2,4,6-tricarboxylate coordination polymers

Two new lanthanide-pyridine-2,4,6-tricarboxylate coordination polymers [Pr(H₂O)₃(ptc)]⋅H₂O (1) and [Tb₂(H₂O)₉(ptc)₂]·3H₂O (2) (H₃ptc = pyridine-2,4,6-tricarboxylic acid) have been synthesized and structurally characterized by single crystal X-ray diffraction. The compound (1) crystallize as 2D layer, which are further engaged in hydrogen bonding leading to a novel 3D supramolecular architecture. Complex (2) exists as a centrosymmetric tetranuclear unit, which are assembled into a 3D supramolecular architecture via extensively hydrogen bonding interaction. The luminescence experiments show that Pr(III) and Tb(III) compounds exhibit typical luminescence in the visible region. Besides luminescence, the magnetic properties of (1) and (2) were investigated and indicate the anti-ferromagnetic couplings between the Ln(III) ions.     

A series of 3d-4f heterometallic three-dimensional coordination polymers: syntheses, structures and magnetic properties

Seven lanthanide-cobalt heterometallic three-dimensional coordination polymers: {[Ln(3)Co(2)(BPDC)(5)(HBPDC)(H(2)O)(5)](ClO(4))(2)·mH(2)O}(n) (Ln = Eu (1, m = 10.25), Gd (2, m = 8), Tb (3, m = 9.5), Dy (4, m = 11), Ho (5, m = 10.5), Tm (6, m = 11), Lu (7, m = 10.25); BPDC = 5,5'-dicarboxylate-2,2'-dipyridine anion) were structurally and magnetically characterized. Compounds 1-7 crystallize in the orthorhombic space group Pbca, featuring a 3D sandwich framework. Magnetic properties of 2-6 have been investigated by using DC (direct current) and AC (alternating current) susceptibility measurements. Among these compounds, only compound 4 displays significant frequency dependence, albeit without reaching the characteristic maxima above 2 K, implying slow magnetic relaxation behavior in 4. After the application of a DC field, good peak shapes of AC signals were obtained and the energy barrier ΔE/k(B) = 62.89 K and the preexponential factor τ(0) = 6.16 × 10(-8) s. To our knowledge, 4 has the highest energy barrier in Ln-Co SMM systems hitherto.     

Synthesis, crystal structure and photoluminescent properties of four lanthanide 5-nitroisophthalate coordination polymers

Four new lanthanide coordination polymers, [Y(Hnip)(nip)(H₂O)]·H₂O (1), [Ln(Hnip)(nip)(H₂O)₂]·2H₂O [Ln=Eu(2), Tb(3)] and [Y(nip)₂]·(H₂4,4′-bpy)_0.5 (4) [5-nip=5-nitroisophthalate, 4,4′-bpy=4,4′-bipyridine], have been hydrothermally synthesized and structurally characterized. Compound 1 features novel lanthanide-carboxylate groups chains composed of three samehanded helical strands intersecting each other through hinged lanthanide atoms, and these chains are cross-linked by phenylene moieties of carboxylate ligands into a 2D layer structure. Compounds 2 and 3 are isomorphous, and contain 1D catenanelike Ln-O-C-O-Ln chains, which are interconnected by phenylene moieties into 2D layer structures. Compound 4, however, displays a 3D architecture sustained by strong hydrogen bonding interactions between the protonated 4,4′-bpy and the carboxyl oxygen atom from [Y₂(nip)₄]²⁻ with 2D layer structure, and 4,4′-bpy as the guest molecules exist in bilayer channel. The studies for the thermal stabilities of the four compounds show that compound 4 is more stable than other compounds. Compound 2 emits characteristic red luminescence of Eu³⁺ ions at room temperature, and its luminescent lifetime and quantum efficiency has been determined.     

Synthesis, crystal structure, and luminescence properties of coordination polymers based on cadmium isonicotinates

Heating a solution of cadmium nitrate and isonicotinic acid in N,N′-dimethylformamide or dimethyl sulfoxide gave three new coordination polymers, [Cd(Inic)₂] · 0.5DMF (I), [Cd₃(DMSO)₆(Inic)₂(SO₄)₂] (II), and [{Cd(DMSO)(Inic)}₂(SO₄)] · 2H₂O (III), which were studied by X-ray crystallography. Compounds I and III were characterized by IR spectroscopy and elemental and thermogravimetric analyses and luminescence spectroscopy.     

Dipyridyl bridged coordination polymers of Cu(II): Synthesis,crystal structure and magnetic study

Two coordination polymers, [Cu(bpp)(H₂O)₂(ClO₄)₂]_n (1) and {[Cu(bpds)₂(ClO₄)₂] · 1.5(H₂O)}_n (2) [bpp, 1,3-bis(4-pyridyl)propane and bpds, 4,4′-bipyridyl disulfide] have been synthesized and characterized by X-ray single crystal diffraction study and magnetic measurement. Both the coordination polymers display 1D chains with perchlorate anions acting as pendant ligands. In 1 undulated polymers are built by Cu(H₂O)₂(ClO₄)₂ units connected by single bpp and in complex 2 Cu(ClO₄)₂ fragments are linked by pairs of bpds ligands to form a double-stranded chain. The crystal packing evidences polymers of 1 involved in weak H-bonding interactions leading to a 3D supramolecular network. Magnetic study reveals weak antiferromagnetic interactions in both complexes.     

Two lead coordination polymers with nitrilotriacetic acid and oxydiacetic acid: synthesis,characterization, and crystal structure

Two lead coordination compounds [Pb₂(nta)]NO₃ (1) and [Pb(oda)] (2) have been synthesized by slow evaporation or hydrothermal conditions using nitrilotriacetic acid (nta) and 2,2′-oxydiacetic acid (oda) as ligands, respectively. Their structures were determined by single-crystal X-ray diffraction and further characterized by X-ray powder diffraction, infrared absorption spectrum, and thermogravimetric analysis. Compound 1 is a 2-D honeycomb-like layer structure with (6,3) topology. When the bonding limit of Pb–O extends from 2.76 to 2.90 Å, potential weak Pb–O bonds can be found in 1, and the 2-D layer structure can be further linked to generate a 3-D 4-connected supramolecular sra net with the (4².6³.8) Schläfli symbol. Compound 2 contains a 1-D infinite Pb–O chain which is connected through µ₃-, µ₄-, and µ₅-coordination modes of oda to form a new 3-D structure.