Hydrothermal synthesis, crystal structure, and properties of two novel binuclear complexes based on Zaltoprofen and 2,2′-bipyridine ligands

Two novel binuclear metal-organic coordination complexes [M₂(Zaltoprofen)₂(Bipy)₂] [M = Cd (I), Zn (II); Zaltoprofen = 5-(1-carboxyethyl)-2-(phenylthio)phenylacetic acid, Bipy = 2,2′-bipyridine) have been synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction, elemental analysis, IR and electronic spectroscopy, powder X-ray diffraction, and fluorescent properties. Complexes I, II crystallize isomorphously in the monoclinic space group P2₁/c. Structural analysis shows that the M(II) atom of I and II is coordinated with four oxygen atoms from the carboxyl group of the Zaltoprofen together with two nitrogen atoms from the Bipy. The 3D structures of the complexes are stabilized by π-π stacking interactions.     

Synthesis,crystal structure and properties of two terbium complexes with 2,2′-bipyridine

Two new complexes {[Tb(2-IBA)₃ · 2,2′-bipy]₂ · C₂H₅OH} (1) and [Tb(2-ClBA)₃ · 2,2′-bipy]₂ (2) (2-IBA = 2-iodobenzoate; 2-ClBA = 2-chlorobenzoate; 2,2′-bipy = 2,2′-bipyridine) were prepared and their crystal structures determined by X-ray diffraction. Complex 1 is composed of two types of binuclear molecules, [Tb(2-IBA)₃ · 2,2′-bipy]₂ (a) and [Tb(2-IBA)₃ · 2,2′-bipy]₂ (b), and an uncoordinated ethanol molecule. In molecule (a), two Tb³⁺ ions are linked by four 2-IBA groups, all bidentate-bridging. In molecule (b), two Tb³⁺ ions are held together by four 2-IBA groups in two coordination modes, bidentate-bridging and chelating-bridging. In the two molecules, each Tb³⁺ ion is further bonded to one chelating 2-IBA group and one chelating 2,2′-bipy molecule, resulting in coordination numbers of eight for (a) and nine for (b). The structural characteristics of 2 are similar to that of molecule (b) in 1. The two complexes, 1 and 2, both emit strong green fluorescence under ultraviolet light with the ⁵D₄ → ⁷F _j (j = 6–3) emission of Tb³⁺ ion observed.     

Synthesis,structure, luminescence and electrochemical and antioxidant properties of anion-controlled silver(I) complexes with 2,2′-(1,4-butanediyl)bis-1,3-benzoxazole

To explore the influence of various anions on the self-assembly and properties of silver complexes, reactions of anions of silver salts with 2,2′-(1,4-butanediyl)bis-1,3-benzoxazole (BBO) afforded four complexes, formulated as [Ag₂(BBO)₂(p-toluenesulfonate)₂] ( 1 ), {[Ag(BBO)(picrate)]}_∞ ( 2 ), {[Ag(BBO)_1/2(o-coumarate)]·DMF}_∞ ( 3 ) and {[Ag₂(BBO)₃](PF₆)₂}_∞ ( 4 ). These complexes were characterized using elemental analysis, infrared spectroscopy and single-crystal X-ray diffraction. The crystal analysis results show that under the influence of coordination modes and steric hindrance of anions, the complexes exhibited binuclear ( 1 ), one-dimensional polymeric ( 2 and 3 ) and two-dimensional polymeric ( 4 ) structures. Compared with the BBO ligand, only complex 1 has a new emission peak at 428 nm, which is attributed to ligand–metal charge transfer. The emission peaks of complexes 2 – 4 are similar to those of the BBO ligand, which can be due to π–π* and n–π* transitions. These results indicate that anions can modulate the structures and luminescent properties of silver complexes. Moreover, cyclic voltammograms of 1 – 4 indicated an irreversible Ag⁺/Ag couple with the order of reversibility being 2 > 1 > 4 > 3 . In vitro antioxidant experiments showed that complex 3 has significant antioxidant activity against superoxide and hydroxyl radicals.     

Synthesis and crystal structure of two coordination polymers based on N,N′-bis(3-pyridylmethyl)pyromellitic diimide and fluorescence thiocyanate sensing

Transition Metal Chemistry - Two N,N′-bis(3-pyridylmethyl)pyromellitic diimide (3-pmpmd) coordination polymers, namely{[Hg(3-pmpmd)I2]·H2O)}n (1), {[Ni2(3-pmpmd)3 (NO3)4]·2CH3OH}n...     

Synthesis,characterization, and crystal structures of two Ag (I) coordination polymers based on biphenyl-2,2′,4,4′-tetracarboxylate

In this article, [Ag₈(btc)₂(2,2′-bpy)₂] _n (1) and [Ag₄(btc)(phen)₂] _n (2) (H₄btc?=?biphenyl-2,2′,4,4′-tetracarboxylic acid, 2,2′-bpy?=?2,2′-bipyridine, phen?=?1,10-phenanthroline) have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR spectra, thermogravimetric analyses, and single-crystal X-ray diffraction. Complex 1 shows a 3-D framework containing a 2-D bilayer network constructed from (btc)^4? with Ag (I), whereas 2 features a 2-D supramolecular bilayer network. The differences of the two complexes demonstrate that nitrogen-containing chelating ligands have a significant effect on the formation and structure of the resulting complexes. Electrochemistry properties of 1 were also studied.     

Synthesis,structures and electrochemical properties of two novel metal–organic coordination complexes based on trimesic acid (H3BTC) and 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (BPO)

Two novel metal–organic coordination complexes [Cu(HBTC)(BPO)]·H₂O (1) and [Co₃(BTC)₂(BPO)₃(H₂O)₂]·5.25H₂O (2), have been synthesized from hydrothermal reaction of metal chloride with the mixed ligands 1,3,5-benzenetricarboxylate (H₃BTC) and bent dipyridyl based ligand 2,5-bis(3-pyridyl)-1,3,4-oxadiazole (BPO), and structurally characterized by elemental analyses, IR, TG and single-crystal X-ray diffraction analysis. The results reveal that each dinuclear Cu^II unit is bridged by two kinds of different ligands (H₃BTC and BPO) to form one-dimensional (1-D) chain structure in complex 1. The adjacent chains for 1 are further linked by π–π stacking interactions and hydrogen bonding interactions to form a three-dimensional (3-D) supramolecular framework. Complex 2 possesses a 3-D network composed of three different cobalt(II) centers [carboxylate-bridged dinuclear cobalt units and mononuclear cobalt ion] and bridging ligands BTC and BPO, which presents the first example of 3-D coordination polymer constructed from the BPO ligands simultaneously showing three different coordination modes. Moreover, the electrochemical behaviors of the two complexes bulk-modified carbon paste electrodes (1-CPE and 2-CPE) have been reported.     

Synthesis, structure, and luminescent properties of three silver(I) complexes with organic carboxylic acid and 4,4′-bipyridine-like ligands

The reactions of AgNO₃ with combinations of 1,2-bis(4-pyridyl)ethane(bpa)/4,4′-bipyridine (bpy), 4,4′-stilbenedicarboxylic acid (H₂sda)/2,2′-diphenylaminedicarboxylic acid (H₂dpadc)/2,6-naphthalenedicarboxylic acid (H₂ndc) in aqueous alcohol/ammonia at room temperature produce block-like crystals of [Ag₂(bpa)_1.5(sda)_0.5](sda)_0.5·7H₂O, [Ag₂(bpa)₂(H₂O)₃](dpadc), [Ag₂(bpy)₂](ndc)·4H₂O. All three complexes consist of 1D infinite silver–ligand cationic chains, interspersed with organic carboxylate anions that provide charge compensation in the crystal structures. The lattice water molecules are situated among the framework of the crystal structure and show rich hydrogen-bonding interactions, which help to orientate the organic carboxylate anions in the crystal packing, and the presence of Ag···N and Ag···Ag contacts contributes to strengthen the frameworks. The luminescent properties and thermogravimetric analyses of the three complexes are also presented.     

Synthesis,crystal structures,and photoluminescence of two new zinc complexes based on 2,2′-thiodibenzoic acid

{[Zn₂(tdba)₂(phen)₂(H₂O)₂]?·?2H₂O?·?2DMF} _n (1) and [Zn(tdba)(bpy)] _n (2) (H₂tdba?=?2,2′-thiodibenzoic acid, phen?=?1,10-phenanthroline, bpy?=?2,2′-bipyridine, DMF?=?dimethylformamide) were hydrothermally synthesized, and characterized by single-crystal X-ray diffraction analysis, FT-IR, and elemental analysis. The obtained complexes exhibit different structures. Compound 1 is 0-D with tdba connecting two Zn ions in a μ ₁–η ¹/μ ₁–η ¹ coordination forming a dinuclear molecule. Each molecule is further connected with neighbors via hydrogen-bonding and π?···?π interactions. Compound 2 displays a 1-D structure in which Zn²⁺ centers are connected via tdba anions into 1-D chains propagating along the a-axis; these chains are further packed via π?···?π interactions. In addition, photoluminescence for 1 and 2 has been investigated.     

Synthesis,crystal structure and magnetic properties of new MnIII–CuII heterometallic aggregates based on multidentate Schiff-base ligands

Reaction of copper powder, manganese(II) nitrates and multidentate Schiff-base ligands in hot methanol solution led to the isolation of two new Mn^III–Cu^II heterometallic aggregates, [Mn₂ ^IIICu₂ ^II(H₂L)₄] · (NO₃)₂ · 2CH₃OH (1) (H₄L=2-[(2-hydroxy-benzylidene)-amino]-2-hydroxymethyl-proane-1,3-diol) and [Mn^IIICu^II ₃(sae)₄(MeOH)(H₂O)₃] · NO₃ · MeOH (2) (H₂sae = salicylidene-2-ethanolamine). Both compounds were characterized by elemental analysis, IR, XPS, EPR, XRPD and single crystal X-ray diffraction. Compound 1 crystallizes in the triclinic space group P 1 with a = 11.1268(4) Å, b = 11.6153(4) Å, c = 11.8129(5) Å, α = 88.435(10)°, β = 80.203(10)°, γ = 77.572(10)°, V = 1469.13(10) ų, Z = 1, R1(wR2) =0.0300(0.0771). Compound 2 crystallizes in the monoclinic space group P2₁/n with a = 18.1715(7), b = 12.9931(5), c = 19.5903(8) Å, β = 97.1980(10)°, V = 4588.9(3) ų, Z = 4, R1(wR2) = 0.0667 (0.1998). The magnetic susceptibilities of 1 and 2 display the antiferromagnetic interactions in both compounds.     

Synthesis and crystal structure of Ni(II) complexes of 2′-(3,5-dibromo-2-hydroxybenzylidene)-3,5-dihydroxybenzoylhydrazide

A new mononuclear nickel(II) complex incorporating a Schiff-base ligand, [NiL₂](DMF)₄ (HL = 2′-(3,5-dibromo-2-hydroxybenzylidene)-3,5-dihydroxybenzoylhydrazide), has been synthesized and characterized by IR, UV-Vis, elemental analysis and X-ray crystal structure analysis. HL is an anionic tridentate ligand. The nickel atom is hexacoordinated with two oxygen atoms from keto group and two oxygen atoms from hydroxy group and two nitrogen atoms from amide, with the two nitrogen atoms occupying the axial positions forming a distorted octahedral coordination sphere.     

Synthesis,structure, and spectroscopy of two benzil-based α-diimine ligands and their palladium(II) complexes

Two α-diimine ligands were prepared in 60–70% yield via p-toluenesulfonic acid-catalyzed condensation reactions from benzil with 4-bromoaniline and with p-anisidine. Palladium(II) complexes were prepared from both ligands in 70–80% yield. X-ray structures were obtained for the ligand prepared from p-anisidine and its palladium(II) complex. A notable feature observed in the former was its unconjugated C–N double bonds, both in the (E)-configuration. The latter structure possessed two molecules of the metal complex in its unit cell, both of which have diimine cores with a degree of conjugation and a nonideal square-planar geometry around palladium caused by the small bite angles (79.61(3) and 79.15(3)°) of the diimine ligands. Solution-phase electronic absorption spectra of the ligands in chloroform have two bands from π→π ^? and n→π ^? transitions at 269–345?nm. Absorption spectra of the complexes in chloroform exhibited bands attributed to ligand-centered transitions that were red-shifted as compared to free ligands. Only the spectrum obtained from a chloroform solution of the palladium(II) complex with the diimine ligand prepared from p-anisidine featured a band at approximately 520?nm, which was assigned to a combination of d _π(Pd)→π ^? and n(Cl)→π ^? transitions.     

Synthesis and liquid crystal properties of dinuclear cyclopalladated 5-alkyl-2-(4′-alkoxyphenyl)pyrimidine and 3-(4′-alkoxyphenyl)-6-alkoxypyridazine complexes

The dinuclear cyclopalladated complexes [Pd(L₁ or L₂)(µ-X)]₂ (HL₁=5-alkyl-2-(4′-alkoxyphenyl)pyrimidine, HL₂=3-(4′-alkoxyphenyl)-6-alkoxypyridazine, X=Cl^?, CH₂ClCOO^?, CH₂BrCOO^?, CH₃CHBrCOO^?, CH₂BrCH₂COO^?, CH₃COO^?) have been synthesized and characterized; their mesogenic properities were determined by DSC and polarizing microscopy. The effect of the bulk and the polarity of the bridging ligands on their mesogenic properties is discussed. The effect of the length of the alkyl chains on the mesogenic properties of these organometallic complexes has also been investigated.     

Syntheses, crystal structures, and magnetic and fluorescence properties of three complexes of mixed flexible N,N′-bis(3-pyridylmethyl)amine and rigid pyromellitate ligands

Three new complexes, {[Mn(Hbpma)₂(pm)(H₂O)₂]·8H₂O}_n, {[Co(Hbpma)₂(pm)(H₂O)₂]·8H₂O}_n and {[Zn(Hbpma)₂(pm)(H₂O)₂]·8H₂O}_n (bpma = N,N′-bis(3-pyridylmethyl)amine and H₄pm = pyromellitic acid) were synthesized and structurally characterized by single-crystal X-ray diffraction. All three complexes are isomorphous consisting of one-dimensional coordination polymers bridged by rigid pm ligands, while the flexible dipyridyl bpma only acts as a terminal ligand. The bpma ligand adopts the trans–trans conformation in all three complexes. The magnetic properties of the Mn(II) and Co(II) complexes show the occurrence of antiferromagnetic interactions between adjacent metal atoms. The Zn(II) complex exhibits fluorescent emission in the solid state at room temperature.     

Synthesis,crystal structures,and magnetic properties of two manganese(II) coordination polymers bearing 1,1′-biphenyl-3,3′-dicarboxylate ligands

Two Mn(II) coordination polymers, namely [Mn(bpda)] _n (1) and [Mn(bpda)(bpy)_0.5] _n (2) (H₂bpda = 1,1′-biphenyl-3,3′-dicarboxylic acid and bpy = 4,4′-bipyridine), have been synthesized from H₂bpdc, bpy, and MnSO₄·2H₂O under hydrothermal conditions. The complexes were characterized by physicochemical and spectroscopic methods, as well as by X-ray crystallography. Compound 1 possesses a 3D structure consisting of carboxylate-bridged edge-sharing Mn–O–Mn double chains. Compound 2 features a 3D open structure with a dinuclear Mn(II) secondary building unit. Magnetic susceptibility measurements of compounds 1 and 2 exhibit antiferromagnetic interactions between the nearest Mn(II), with J = –11.3 cm⁻¹ and g = 2.12 for 1, and J = –13.5 cm⁻¹ and g = 2.12 for 2.     

Synthesis,crystal structures and photoluminescent properties of two Cd(II)/Zn(II) coordination polymers with rarely 8-/2-fold interpenetrated based on 4,4′-stilbenedicarboxylic acid and imidazole ligands

Two coordination polymers, [Cd(sbdc)(bmib)]_n (1) and {[Zn(sbdc)(tib)]·0.5H₂O}_n (2) (H₂sbdc = 4,4′-stilbenedicarboxylic, bmib = 1,4-bis(2-methylimidazol-1-yl)butane, tib = 1,3,5-tris(1-imidazolyl)benzene), have been synthesized under solvothermal conditions, characterized by elemental analysis, infrared spectra, thermogravimetric analysis, and single-crystal X-ray diffraction. Single-crystal X-ray diffraction analysis reveals that 1 and 2 show 8-fold and 2-fold interpenetrating 3-D frameworks, respectively. Complexes 1 and 2 display a 4-connected (6⁶) sqc6 and a 4-connected (4⁴·6²) sql topology, respectively. Photoluminescent and thermal properties of 1 and 2 have also been investigated.     

Ruthenium(II) 2,2′-bipyridine complexes incorporating substituted phenylazo-(2-(phenylthio))phenylmethine ancillary ligands. Synthesis,crystal structure,spectroscopic and redox properties

Abstract  

Five ruthenium complexes bearing phenylazo-(2-(phenylthio))phenylmethine ligands of the general type trans-[Ru^II(bpy)(L)(Cl)₂] (C1–C5) {L = YC₆H₄N=NC(COCH₃)=NC₆H₄(2-SC₆H₅), H (L1), Cl (L2), OCH₃ (L3), Br (L4), or NO₂ (L5)} have been synthesized. The crystal structure of trans-[Ru(bpy)(L1)(Cl)₂] (C1) is reported and shows no direct metal–S interaction. The complexes have been characterized through spectroscopic (IR, UV/vis and NMR) and electrochemical (CV) techniques. The electrochemical parameters (E _L(L)) of the azoimine ligands are reported.     

1H-3-(2-pyridyl)-5-(3-pyridyl)-1,2,4-triazole (2,3′-Hbpt) as ligand in Cd(II) complexes: synthesis,crystal structures,and fluorescence

Hydrothermal reactions of 1H-3-(2-pyridyl)-5-(3-pyridyl)-1,2,4-triazole (2,3′-Hbpt) with CdCl₂ and CdI₂ yielded three new coordination polymers, {[CdCl(2,3′-bpt)(H₂O)]·2H₂O}_n (1), {[Cd₂I₃(2,3′-H_0.5bpt)₂]}_n (2), and [CdI₃(2,3′-Hbpt)](2,3′-H₂bpt)·H₂O (3). Structural analysis reveals that 1 has a 1-D double chain structure; in 2, 2,3′-bpt bridges adjacent Cd(II) ions to form a 1-D twofold helical chain, which further connects via μ₂-I^-, giving a 2-D grid structure in the ab plane; 3 is mononuclear. These complexes are further connected through weak hydrogen bonding interactions, and/or weak π···π stacking interactions, to generate 3-D supramolecular structures. The fluorescence properties of 1 and 2 have been investigated in the solid state at room temperature.     

Syntheses,crystal structures and fluorescent properties of two 4,4′-dipyridylsulfide based zinc(II) and cadmium(II) helical complexes

Two allomeric helical coordination polymers, {[Zn(4,4′-dps)₂(HSSA)(H₂O)₂] · 3(H₂O)} _n (1) and {[Cd(4,4′-dps)₂(HSSA)(H₂O)₂] · 3(H₂O)} _n (2) (4,4′-dps = 4,4′-dipyridylsulfide, H₃SSA = 5-sulfosalicylic acid), have been synthesized by similar experimental methods and characterized by elemental analysis, single-crystal X-ray diffraction, and fluorescence spectra. Both crystallize in monoclinic system, space group P₂1/n, with a = 11.7947(13) Å, b = 13.7475(15) Å, c = 20.183(2) Å, and Z = 4 for 1 and a = 11.940(7) Å, b = 14.068(8) Å, c = 20.323(12) Å, and Z = 4 for 2. In both complexes, the metal (Zn^II for 1 and Cd^II for 2) are six-coordinate with a N₃O₃ donor set in a distorted octahedron. Half of the 4,4′-dps are μ ₂-bridging, linking adjacent metal centers and forming P₂1/n dimensional helical structures along the b-axis. Fluorescence measurements show that 1 and 2 have medium fluorescent emission at 402 and 405 nm, respectively.