Syntheses,crystal structures and luminescent investigations of cobalt(II) and zinc(II) complexes with 2-propyl-4,5-dicarboxylate-imidazole (H3PIDC)

Presented in this communication are four metal complexes based on 2-propyl-4,5-dicarboxylate-imidazole (H₃PIDC), including two Co(II) coordination compounds, [Co(H₂PIDC)₂(H₂O)₂] · 4H₂O (1) and 2[Co(H₂PIDC)₂(H₂O)₂] · 5H₂O (2), as well as two Zn(II) coordination compounds, [Zn(H₂PIDC)₂(H₂O)₂] · 4H₂O (3) and 2[Zn(H₂PIDC)₂(H₂O)₂] · 7H₂O (4). They contain the same coordinated unit of [M(H₂PIDC)₂(H₂O)₂] (M = Zn or Co). Interestingly, among these four complexes, 1 and 2, or 3 and 4 crystallized in different space group, which may be related with the number of the crystallized H₂O molecules.     

Absolute helicity of 1D chains influenced by enantiopure ligands

Two novel coordination polymers, [Cd(D-1-Hcam)(nta)(H₂O)₂]₂[Cd(D-3-Hcam)(nta)(H₂O)₂]₂·4H₂O (1) and [Cd(DL-Hcam)(nta)(H₂O)₂]·H₂O (2) (D-1-Hcam/D-3-Hcam = monodehydrated d-camphoric acid, Hnta = nicotinic acid and DL-Hcam = monodehydrated dl-camphoric acid), have been synthesized under hydrothermal conditions. Complex 1 is a three-dimensional hydrogen bonding framework composed of two kinds of 1D helical chains which exhibit the same right-handed helix, whereas complex 2 is constructed with one kind of 1D racemic chains. Interestingly, both two chiral molecules in the structures play important roles in the absolute helicity although they are not in the backbones of the helix which are made of rigid achiral ligands. Furthermore, different coordination modes of chiral ligands regulated the fluorescent emission.     

Copper(II) and cadmium(II) complexes with an imide tethered imidazole and a copper(II) coordination polymer through ring opening reaction

The reactions of 2-(3-(1H-imidazol-1-yl)propyl)isoindoline-1,3-dione (L) with copper (II) chloride or copper(II) nitrate resulted in mononuclear complexes [CuL₄Cl₂]·12H₂O (1) or [CuL₄(H₂O)NO₃]NO₃·2H₂O (2) respectively; whereas the copper(II) acetate reacted with L to give a three dimensional coordination polymer {[Cu(L′)₂]·4H₂O}n (3), (where L′ = 2-(3-(1H-imidazol-1-yl)propylcarbamoyl)benzoate). The reaction of cadmium(II) acetate with L led to the formation of a seven-coordinated complex [CdL₃(O₂CCH₃)₂]·2H₂O (4).     

Six-, seven- and eight-coordinated Cd(II) ions with N-heterocyclic multicarboxylic acids

Two novel cadmium complexes [Cd₃(pta)₂(H₂O)₄]_n (1) (H₃pta = 2,4,6-pyridinetricarboxylic acid) and {[Cd(H₂pza)(H₂O)₂] · 2H₂O}_n (2) (H₄pza = 2,3,5,6-pyrazinetetracarboxylic acid) were synthesized. In both complexes, Cd(II) ions show three different coordination numbers of six and seven in 1 and eight in 2, respectively. Complex 1 displays a three-dimensional network structure and 2 shows a one-dimensional chain structure. The one-dimensional chains in 2 are vertical or parallel to each other and form a three-dimensional network structure by hydrogen bonds. In addition, 1 emits intense fluorescence on excitation of 342 nm.     

Synthesis,crystal structure and nonlinear optical property of cadmium(II) and copper(II) complexes with novel chiral ligand

Two novel metal-organic frameworks (MOFs) [Cd(3-MPCA)₂ · H₂O] · 5.5H₂O (1) and [Cu(3-MPCA)₂ · H₂O] · 4H₂O (2) [3-MPCA⁻ = (1R, 3S)-1,2,2-trimethyl-3-(pyridin-3-ylmethylcarbamoyl)cyclopentanecarboxylate] were hydrothermally synthesized and characterized by X-ray crystallography. Complexes 1 and 2 are homochiral and have similar one-dimensional (1D) chain structure, which are further linked by strong hydrogen bonds to give 3D architectures. There are oxygen hexmers and heptamers from water molecules and carbonyl group in 1 with O⋯O distances and O–O–O angles comparable to the corresponding values in ice. Nonlinear optical measurements on powdered sample of 1 and 2 revealed that they display second-harmonic-generation (SHG) response of 0.8 and 0.3 times of that for urea, respectively.     

Formation of a 1D water chain into the channel of a unique 3D hydrogen-bound coordination polymer {[Cd(μ-Cl)(4-pya)(H2O)]2 · 4H2O}∞ (4-pya = trans-4-pyridylacrylate)

A novel Cd(II)/4-pya coordination polymer {[Cd(μ-Cl)(4-pya)(H₂O)]₂ · 4H₂O}_∞ (1) (4-pya = trans-4-pyridylacrylate) was synthesized and structurally characterized. Single-crystal X-ray diffraction revealed that 1 consists of a 2D (4, 4) network constructed from the 4-pya bridging ligand and the dimeric [Cd(μ-Cl)]₂ cores, in which each six-coordinated Cd(II) ion adopts an octahedral coordination geometry. Each 2D layer is further stacked along the a axis through hydrogen bonding interactions to afford a 3D hydrogen-bound network. An infinite water chain is generated via hydrogen bonds into each resulting 1D channel. The luminescent properties of 1 in the solid state were investigated.     

Three new coordination polymers based on 4-oxo-1(4H)quinolineacetate: Synthesis,structures and luminescent properties

Reactions of 4-oxo-1(4H)-quinolineacetic acid (Hoqa) and varied metal salts of Zn(II), Cd(II) and Ag(I) resulted in the formation of three new coordination polymers, namely, [Zn(oqa)₂]·H₂O (1), [Cd(bpy)(oqa)₂(H₂O)₂]·4H₂O (2) and [Ag(bpy)(oqa)]·2H₂O (3) (bpy = 4,4′-bipyridine). Complex 1 has a three-dimensional (3D) polymeric network with diamondoid topology; compounds 2–3 exhibit one-dimensional (1D) chain structure characteristics, which are further assembled through π–π stacking attractions and hydrogen bonds, forming the 3D supramolecular frameworks. In addition, the solid-state luminescent properties of the ligand Hoqa and complexes 1–2 have been investigated at room temperature.     

Low-dimensional compounds containing bioactive ligands. Part VI. Spectral and structural characterizations of a unique zinc(II) compound with biologically active ligand — clioquinol

The investigated compound of {[Zn(CQ)₂(H₂O)₂]₂[Zn(CQ)₂(H₂O)]₃}·5DMF·2H₂O (1) composition (where CQ = 5-chloro-7-iodo-quinolin-8-ol, DMF = N,N-dimethylformamide) was prepared by simple mixing of ZnCl₂ and CQ. Infrared spectroscopy confirmed the presence of CQ, DMF and H₂O molecules in the prepared compound. X-ray structural analysis revealed that the structure of the title compound consists of five independent Zn(II) atoms, which are coordinated by two bidentately coordinated molecules of CQ. Three of these central atoms are also coordinated by one water molecule, while the other two have two water molecules in the coordination sphere. The structure of 1 also includes five solvated DMF and two water molecules involved in thirteen hydrogen bonds, which interconnect different complex species to form four “triplets”, in the centre of which are units with hexacoordinated Zn atoms surrounded by two units with pentacoordinated Zn atoms. These triplets are linked together to chains parallel with the b axis by two kinds of π–π interactions.     

Synthesis,crystal structure and properties of Zn(II) and Cd(II) complexes with 2-(4-isopropyl-4-methyl-5-oxo-4,5-dihydro-1H-imidazol-2-yl)nicotinic acid ligand

Two novel complexes, namely [Cd(L)₂] (1) and [Zn(L)₂(H₂O)₂] (2) have been synthesized (HL = 2-(4-isopropyl-4-methyl-5-oxo-4,5-dihydro-1H-imidazol-2-yl)nicotinic acid), which are characterized by elemental analysis, infrared spectrum and X-ray crystal diffraction. While strong hydrogen bonds play central roles in the formation of the 3D structure, the combined influence of the weak interactions such as C–H?O bonds, carbonyl?π and C–H?π interactions are also evident in the structures. The preliminary investigation on the thermal and fluorescence property of the complexes are presented.     

Construction and photoluminescence properties of two novel zinc(II) and cadmium(II) benzyl-tetrazole coordination polymers

Two new d¹⁰ coordination polymers, Zn(Beta)₂ (1) and Cd₂(Beta)₃Cl(H₂O) (2) (Hbeta = 5-benzyl-tetrazole) have been synthesized by the in situ [3 + 2] cycloaddition reaction of 5-benzylacetonitrile, sodium azide and MCl₂ [M = Zn (1); M = Cd (2)] under hydrothermal condition. Complex 1 is a coordination polymer comprised of numerous mildly undulated two-dimensional (2D) layers with a (4, 4) topological network; while complex 2 is a 3D coordination framework constructed from the interconnection of various helical chains through cadmium–chlorine bridges. Furthermore, the luminescence properties of two complexes have been investigated.     

Spectroscopic studies on bis(1-amidino-O-alkylurea) copper(II) sulfate complexes where alkyl = methyl,ethyl, n-propyl or n-butyl: EPR evidence for binuclear complexes

Four new Cu(II) Complexes viz. [Cu(II)(1-amidino-O-methylurea)₂]SO₄·2H₂O (1), [Cu(II)(1-amidino-O-ethylurea)₂](SO₄)₂·2H₂O (2), [Cu(II)(1-amidino-O-n-propylurea)₂] SO₄·2H₂O (3), [Cu(II)(1-amidino-O-n-butylurea)₂]₂(SO₄)₂·2H₂O (4) have been synthesized and characterized. EPR spectrum of complex 4 at RT consisted of fine-structure transitions (ΔMs = ±1) with zero-field splitting (ZFS) of 0.0485 cm^?1 and a half-field signal (ΔMs = ±2) at ca. 1600 G, revealed formation of binuclear complex (S = 1). Whereas EPR spectrum of complex 2 in DMSO showed a mixture of mononuclear and binuclear complex in the ratio 0.75:1.0 with ZFS of 0.0385 cm^?1. From the temperature dependence of the EPR signal intensity, the isotropic exchange-interaction constant J was evaluated.     

Syntheses and physical properties of three-dimensional coordination polymers with the flexible tripodal ligand 1,3,5-tris(1,2,4-triazol-1-ylmethyl)benzene

Two 3D organic–inorganic hybrid coordination polymers, [M₂(ttmb)₂(SO₄)₂(H₂O)₂] · 7H₂O (M = Cd, 1; M = Mn, 2; ttmb = 1,3,5-tris(1,2,4-triazol-1-ylmethyl)benzene), have been synthesized and structurally characterized. They are isostructural and possess a 3D architecture fused from 2D (4,4) M(ttmb) networks and MSO₄ chains by sharing “hinge” metal atoms. The thermal properties of 1 and 2, luminescent property of 1 as well as magnetic property of 2 have been investigated.     

Unusual metal–organic network constructed from Zn(II), benzenetricarboxylate and bis(1,2,4-triazolyl)pyridine

Hydrothermal reaction of ZnSO₄ · 7H₂O with 1,3,5-benzenetricarboxylic acid (H₃btc) and 2,6-bis(1,2,4-triazolyl)pyridine (btp) afforded a novel metal–organic network {[Zn₃(btc)₂(btp)₂(H₂O)₂] · 4H₂O}_n (1) with a supramolecular cocrystal [H₃btc · btp · H₂O]_n (2). The complex 1 exhibits an unusual network containing two molecular squares and a rectangle. The networks interpenetrate to make a 3D metal–organic framework, which is quite thermal stable. Compound 2 shows a 2D supramolecular network assembled through strong hydrogen bonds.     

Tuning the valence of 3,3-di(1H-tetrazol-5-yl)pentanedioic acid: Solvothermal synthesis of Eu(III) and bimetallic Eu(III)/Cu(II) compounds

3,3-Di(1H-tetrazol-5-yl)pentanedioic acid (H₄dtzpda) with four acidic hydrogen atoms can display different valence when reacted with different metal ions. Solvothermal reactions of H₄dtapda with Eu(NO₃)₃·6H₂O or Eu(NO₃)₃·6H₂O/Cu(NO₃)₂·6H₂O afford [Eu(Hdtzpda)(H₂O)₄]·4H₂O (1) and [Eu₂Cu(dtzpda)₂(H₂O)₁₀]·6H₂O (2), respectively, where only three acidic hydrogen atoms of H₄dtzpda are deprotonated in compound 1 while all the four acidic ones are deprotonated in compound 2. In compound 1, Hdtzpda^3 − acts as a pentadentate ligand to bridge Eu(III) centers via the oxygen atoms of the carboxylate group while in compound 2, dtzpda^4 − is a hepadentate one via not only the oxygen atoms of the carboxylate group but also the nitrogen atoms of the tetrazole rings. The luminescence properties of the two compounds in the solid state show both intraligand and characteristic peaks of Eu^3 + at room temperature.     

Nested [Na6(H2O)]6+ encapsulation of nickel(II) coordination framework assembled from pyridyl-2,6-dicarboxylic acid

Hydrothermal reactions of pyridyl-2,6-dicarboxylic acid (H₂PDC) and NiCl₂ · 6H₂O in the presence of NaOH and KOH, respectively afforded the products, {[Ni(PDC)(Cl)](Na)(H₂O)/3}_n (1) and K₂[Ni(PDC)₂] · 7H₂O (2), of which 1 was characterized consisting of 3-D porous framework and [Na₆(H₂O)]⁶⁺ inclusions, and 2 was a mononuclear complex with potassium hydrate as counterion.     

One-dimensional nanoporous M2L2 rhombohedral molecular square with strong blue fluorescent emission

The hydrothermal reactions of Zn(ClO₄)₂ · 6H₂O and Cd(ClO₄)₂ · 6H₂O with the ligand N,N^′-bis(pyridylcarbonyl)-4,4^′-diaminodiphenyl ether (L) afford two one-dimensional (1D) coordination polymers, ([CdL(ClO₄)₂ · (H₂O)₂] · 2H₂O) (1) and [ZnL(ClO₄)₂ · (H₂O)₂] · 2H₂O, (2) having a nanoporous M₂L₂ rhombohedral molecular square with an approximately accessible cavity of 12.9 × 12.9 (1) and 12.7 × 12.7 (2) Å without any interpenetrations. Both 1 and 2 are isostructural and display very strong blue fluorescent emission in the solid state at room temperature.     

Diversity of carboxylate coordination in two novel zinc(II) cinnamate complexes

Two novel mixed-ligand zinc(II) complex compounds [Zn(cinn)₂(mpcm)]_n (1) and [Zn(p-HO-cinn)₂(nia)(H₂O)₂] · H₂O (2) (cinn = cinnamato, mpcm = methyl-3-pyridylcarbamate, nia = nicotinamide) were prepared and characterized by elemental analysis, infrared spectroscopy, single crystal X-ray diffraction and thermal analysis. Diverse modes of carboxylate coordination were found in the complexes. In 1 the cinnamate ligands coordinate as monodentate and bridging (syn–anti), respectively. The syn–anti carboxylate bridges connect the molecules of 1 to infinite polymeric helical chains. The structure of 2 is monomeric. One of the carboxylate oxygens of p-hydroxycinnamate is semi-coordinated (Zn–O = 2.549(2) Å).     

Two Mn(II)–Au(I) supramolecular assemblies bonded by coordination,aurophilicity and hydrogen-bonding, π–π interactions and their magnetic properties

Two Mn(II)–Au(I) supramolecular assemblies {{Mn[Au(CN)₂]₂(H₂O)₄} [Au(CN)₂]₂(H₂bpy) · H₂O}(bpy = 4,4′-bipyridine) 1 and {Mn(4,4′-dmbpy) [Au(CN)₂]₂(CH₃OH)} (4,4′-dmbpy = 4,4′-dimethyl-bipyridine) 2 have been synthesized and magnetic properties have been investigated The interplay of aurophilicity, coordination, hydrogen-bonding and π–π interactions in two complexes result in three-dimensional network.     

1D chain lanthanide coordination polymers with 6-hydroxynicotinic acid: Crystal structures and luminescent properties

Four new lanthanide coordination polymers {[Ln(HL)₂(H₂O)₅] · HL ·  H₂O}_n (Ln = Sm for 1, Eu for 2, Tb for 3 and Dy for 4) (H₂L = 6-hydroxynicotinic acid) have been synthesized and characterized by elemental analysis, FT-IR spectra and X-ray single-crystal diffraction. They all exhibit 1D chain structure, which are further linked via hydrogen bonds to form 3D supramolecular architecture. Luminescent properties of these lanthanide coordination polymers are studied.     

A novel three-dimensional cadmium(II) coordination polymer constructed from dinuclear molecular building block,syntheses, structure and photoluminescence property

A novel cadmium(II) coordination polymer, [Cd₂(pzdc)₂(4,4′-bpy)₂]·4H₂O (1) (H₂pzdc = pyrazine-2,3-dicarboxylic acid; 4,4′-bpy = 4,4′-bipyridine), has been synthesized by hydrothermal reaction of Cd(OAC)₂, H₂pzdc and 4,4′-bpy. Single-crystal X-ray diffraction analysis reveals that 1 constructed from dinuclear building blocks has a three-dimensional (3-D) structure with rob topology. Fluorescent measurement of 1 exhibits strong blue-green emission in the solid state at room temperature, and its framework possess remarkable thermal stability.