Metal(II) Ion Complexes with 5‐(Pyrazin‐2‐yl)‐2,4‐dihydro‐3H‐1,2,4‐triazole‐3‐thione; Synthesis,Structural Characterization,Acid‐base,and Complexing Properties in Solution

The study reports the synthesis of complexes Co(HL)Cl₂ ( 1 ), Ni(HL)Cl₂ ( 2 ), Cu(HL)Cl₂ ( 3 ), and Zn(HL)₃Cl₂ ( 4 ) with the title ligand, 5‐(pyrazin‐2‐yl)‐1,2,4‐triazole‐5‐thione (HL), and their characterization by elemental analyses, ESI‐MS (m/z), FT‐IR and UV/Vis spectroscopy, as well as EPR in the case of the Cu^II complex. The comparative analysis of IR spectra of the metal ion complexes with HL and HL alone indicated that the metal ions in 1 , 2 , and 3 are chelated by two nitrogen atoms, N(4) of pyrazine and N(5) of triazole in the thiol tautomeric form, whereas the Zn^II ion in 4 is coordinated by the non‐protonated N(2) nitrogen atom of triazole in the thione form. pH potentiometry and UV/Vis spectroscopy were used to examine Co^II, Ni^II, and Zn^II complexes in 10/90 (v/v) DMSO/water solution, whereas the Cu^II complex was examined in 40/60 (v/v) DMSO/water solution. Monodeprotonation of the thione triazole in solution enables the formation of the L:M = 1:1 species with Co^II, Ni^II and Zn^II, the 2:1 species with Co^II and Zn^II, and the 3:1 species with Zn^II. A distorted tetrahedral arrangement of the Cu^II complex was suggested on the basis of EPR and Vis/NIR spectra.     

A Dynamic Crystal‐to‐Amorphous Transformation Microporous ZnII Mixed Neutral‐ligand Metal‐organic Polymer {[Zn(bpp)2(μ‐4,4′‐bipy)(H2O)2](ClO4)2·H2O}n

A new rarely reported Zn^II mixed‐polypyridine coordination polymer with both rigid and flexible spacers, {[Zn(bpp)₂(μ‐4,4′‐bipy)(H₂O)₂](ClO₄)₂ · H₂O}_n ( 1 ), has been synthesized and characterized by elemental analysis, IR‐, ¹H NMR‐, ¹³C NMR spectroscopy and single‐crystal X‐ray diffraction. The thermal stability of compound 1 was studied by thermal gravimetric (TG) and differential thermal analyses (DTA). The single‐crystal X‐ray structure of 1 shows that the complex has been formed from a 1D polymer as a result of bridging by the 4,4′‐bipy ligands. Solution and solid‐state luminescent spectra of the compound 1 indicate intense fluorescent emissions at ca. 353.6 and 468.8 nm, respectively. Removal of the interstitial water guest molecules results in a loss of crystallinity, but exposure to water vapor reestablishes the original structure, thus constituting 1 as a third‐generation porous framework.     

Synthesis,Crystal Structures and Fluorescent Properties of Two 2,2′‐Biquinoline‐4,4′‐dicarboxylate‐based Cadmium(II) and Cobalt(II) Complexes

Two metal‐organic coordination polymers with one‐dimensional infinite chain motif, [Cd(bqdc)(phen)₂]_n ( 1 ) and [Co(bqdc)(phen)(H₂O)₂]_n ( 2 ) (H₂bqdc = 2,2′‐biquinoline‐4,4′‐dicarboxylic acid, phen = 1,10‐phenanthroline), have been synthesized under similar solv/hydrothermal conditions and fully structural characterized by elemental analysis, IR, and single‐crystal X‐ray crystallography. Their thermal stability and photoluminescence properties were further investigated by TG‐DTA and fluorescence spectra. In both complexes, the adjacent metal ions (Cd^II for 1 and Co^II for 2 ) are linked together by dicarboxylate groups of bqdc dianions in chelating bidentate and monodentate modes, respectively, generating a zigzag chain for 1 and linear chain for 2 . The relatively higher thermal stability up to 324 °C for 1 and strong fluorescence emissions jointly suggest that they are good candidates for luminescent materials.     

Syntheses,Spectra, Thermal Studies and Crystal Structures of Vitamin B13 Complexes of Nickel(II) with N,N,N′,N′‐Tetramethylethylenediamine and 2,2‐Dimethylpropane‐1,3‐diamine

Two nickel(II) complexes of vitamin B13 (H₃Or) with N,N,N′,N′‐tetramethylethylenediamine (tmen) and 2,2‐dimethylpropane‐1,3‐diamine (dmpen) were synthesized and characterized by means of elemental and thermal analyses, magnetic susceptibility, and IR and UV/Vis spectroscopic studies. The crystal structures of mer‐[Ni(HOr)(H₂O)₂(tmen)] · H₂O ( 1 ) and [Ni(HOr)(dmpen)₂] ( 2 ) were determined by using single‐crystal X‐ray diffraction. In the complexes, which crystallize in the triclinic system (space group for 1 ) and the monoclinic system (space group P2₁/c for 2 ), the Ni^II ions exhibit a distorted octahedral coordination. Ni^II ions are chelated by the deprotonated nitrogen atom of the pyrimidine ring and the oxygen atom of the carboxylate group, the distorted octahedral coordination completed by one tmen and two aqua ligands for 1 or two dmpen ligands for 2 .     

Synthese,Struktur und EPR‐Untersuchungen von binuklearen Bis(N,N,N‴,N‴‐tetraisobutyl‐N′,N″‐isophthaloylbis(thioureato))‐Komplexen des CuII,NiII, ZnII,CdII und PdII

Synthesis, Structure and EPR Investigations of binuclear Bis(N,N,N?,N?‐tetraisobutyl‐N′,N″‐isophthaloylbis(thioureato)) Complexes of Cu^II, Ni^II, Zn^II, Cd^II and Pd^II The synthesis of binuclear Cu^II‐, Ni^II‐, Zn^II‐, Cd^II‐ and Pd^II‐complexes of the quadridentate ligand N,N,N?,N?‐tetraisobutyl‐N′,N″‐isophthaloylbis(thiourea) and the crystal structures of the Cu^II‐ and Ni^II‐complexes are reported. The Cu^II‐complex crystallizes in two polymorphic modifications: triclinic, (Z = 1) and monoclinic, P2₁/c (Z = 2). The Ni^II‐complex was found to be isostructural with the triclinic modification of the copper complex. The also prepared Pd^II‐, Zn^II‐ and Cd^II‐complexes could not be characterized by X‐ray analysis. However, EPR studies of diamagnetically diluted Cu^II/Pd^II‐ and Cu^II/Zn^II‐powders show axially‐symmetric g and A ^Cu tensors suggesting a nearly planar co‐ordination within the binuclear host complexes. Diamagnetically diluted Cu^II/Cd^II powder samples could not be prepared. In the EPR spectra of the pure binuclear Cu^II‐complex exchange‐coupled Cu^II‐Cu^II pairs were observed. According to the large Cu^II‐Cu^II distance of about 7,50Å a small fine structure parameter D = 26·10^?4 cm^?1 is observed; T‐dependent EPR measurements down to 5 K reveal small antiferromagnetic interactions for the Cu^II‐Cu^II dimer. Besides of the dimer in the EPR spectra the signals of a mononuclear Cu^II species are observed whose concentration is T‐dependent. This observation can be explained assuming an equilibrium between the binuclear Cu^II‐complex (Cu^II‐Cu^II pairs) and oligomeric complexes with “isolated” Cu^II ions.     

Synthesis,Spectral, Thermal Studies of Co(II), Ni(II), Cu(II) and Zn(II)‐arginato Complexes. Crystal Structure of Monoaquabis(arginato‐κO,κN)copper(II). [Cu(arg)2(H2O)].NaNO3

Transition metal complexes of arginine (using Co(II), Ni(II), Cu(II) and Zn(II) cations separately) were synthesized and characterized by FTIR, TG/DTA‐DrTG, UV‐Vis spectroscopy and elemental analysis methods. Cu(II)‐Arg complex crystals was found suitable for x‐ray diffraction studies. It was contained, one mole Cu^II and Na⁺ ions, two arginate ligands, one coordinated aqua ligand and one solvent NO₃^? group in the asymmetric unit. The principle coordination sites of metal atom have been occupied by two N atoms of arginate ligands, two carboxylate O atoms, while the apical site was occupied by one O atom for Cu^II cation and two O atoms for Co^II, Ni^II, Zn^II atoms of aqua ligands. Although Cu^II ion adopts a square pyramidal geometry of the structure. Co^II, Ni^II, Zn^II cations have octahedral due to coordination number of these metals. Neighbouring chains were linked together to form a three‐dimensional network via hydrogen‐bonding between coordinated water molecule, amino atoms and O atoms of the bridging carboxylate groups. Cu^II complex was crystallized in the monoclinic space group P2₁, a = 8.4407(5) Å, b = 12.0976(5) Å, c = 10.2448(6) Å, V = 1041.03(10) ų, Z = 2. Structures of the other metal complexes were similar to CuII complex, because of their spectroscopic studies have in agreement with each other. Copper complex has shown DNA like helix chain structure. Lastly, anti‐bacterial, anti‐microbial and anti‐fungal biological activities of complexes were investigated.     

Synthesis and Structural Characterization of Cadmium(II) and Mercury(II) Complexes Derived from 3‐Aminoquinoline

Two novel metal complexes derived from interactions of Cd²⁺ and Hg²⁺ ions with 3‐aminoquinoline in the molar ratio 1 : 2 are reported. The synthesized and isolated metal complexes were characterized by UV/VIS, FT‐IR, ¹H‐ and ¹³C‐NMR, and ESI‐MS spectroscopic studies, and elemental analyses. FT‐IR and NMR studies confirmed that the NH₂ group remains uncoordinated in both synthesized complexes. The molecular structure of the Cd^II complex was additionally determined by X‐ray single‐crystal analysis. The Cd complex crystallizes in the triclinic centrosymmetric P$\bar 1$ space group. Moreover, the Cd^II complex exists as neutral discrete molecule and was found to show tetrahedral geometry.     

[Bis(3,5‐dimethylpyrazol‐1‐yl‐κN2)hydro(pyrazol‐1‐yl‐κN2)borato][(3,5‐dimethylpyrazol‐1‐yl‐κN2)dihydro(pyrazol‐1‐yl‐κN2)borato]nickel(II)

The title compound, [Ni(C₈H₁₂BN₄)(C₁₃H₁₈BN₆)] or Bp′Tp′Ni^II, where Bp′ is (3,5‐dimethylpyrazol‐1‐yl)dihydro(pyrazol‐1‐yl)borate and Tp′ is bis(3,5‐dimethylpyrazol‐1‐yl)hydro(pyrazol‐1‐yl)borate, contains a divalent Ni^II centre bound by the chelating N atoms of the polysubstituted pyrazolylborate ligands. It is shown to lack a strong agostic B—H...Ni interaction, implying that the sixth coordination site is unoccupied in the solid state. This square‐pyramidal complex is the only known crystal structure where the Ni^II centre is pentacoordinated while bonded exclusively to pyrazolyl units. This is of interest with respect to electrochemical and catalytic properties.     

An Extremely Simple Dibenzopentalene Synthesis from 2‐Bromo‐1‐ethynylbenzenes Using Nickel(0) Complexes: Construction of Its Derivatives with Various Functionalities

Nice and easy : A very simple synthesis for dibenzopentalenes, which starts from 1‐bromo‐2‐ethynylbenzenes, has been developed. It uses Ni⁰ complexes (see scheme), from which a relatively stable Ni^II complex as an important intermediate has been isolated. Dibenzopentalenes with various functional groups can be prepared by the procedure, and their electronic properties are consistent with theoretical calculations.

     

Synthesis and Structural Characterization of a Binuclear Mixed‐Ligand (Salicylate and N,N‐diethylnicotinamide) Nickel(II) Complex,Its Magnetic Properties. [Ni2(µ‐Sal)4(Dena)2]H2O

The title complex of [Ni₂(µ‐Sal)₄(Dena)₂]H₂O, [( µ‐tetrakissalicylato‐κ‐O,O)(bis‐N,N‐diethylnicotinamide‐κ‐N)(binickel(II))]hydrate, C₄₈H₅₂Ni₂N₄O₁₆, has been synthesized and explained as structural using some elemental analysis, FT‐IR spectra, UV‐Vis reflectance, magnetic measurements, thermal analysis and x‐ray diffraction methods. The analysis results showed that the unit cell of complex includes two molecules Ni^II cation, four molecules salicylates as bridge and two molecules N,N‐diethylnicotinamide ligands, also there is one molecule hydrated aqua. The compound crystallizes in the monoclinic space group P2₁/c with the following unit‐cell parameters: a =13.6776(6) Å, b =10.5238(3) Å, c =21.8165(9), α=90.00°, β=126.546(3)°, γ=90.00º and Z=2. The compound [Ni₂(µ‐Sal)₄(Dena)₂]H₂O is a typical paddle‐wheel complex structure. Two Ni^II ions are bridged by four salicylate ligands (O2, O2ⁱ, O3, O3ⁱ, O5, O5ⁱ, O6 and O6ⁱ) using a µ‐COO^? coordination mode [symmetry code: (i) 1‐x, 1‐y, 1‐z]. Each Ni^II also coordinates to one nitrogen atom (N1 and N1ⁱ) from one N,N‐diethylnicotinamide ligand molecule in the axial position. The complex has strong paramagnetic properties.     

Synthesis,IR Spectrum,Thermal Analysis,and Crystal Structure of the Cyano‐bridged Heteronuclear Polymeric Complex: [Zn(teta)Ni(μ‐CN)2(CN)2]n

The heteronuclear polymeric complex, [Zn(teta)Ni(μ‐CN)₂(CN)₂]_n (teta: triethylenetetramine), was synthesized and characterized by elementel analysis, FT‐IR spectroscopy, thermal analysis and single crystal X–ray diffraction techniques. The complex crystallizes in the monoclinic system, space group P2₁/c and in which the Zn^II ion exhibits a distorted octahedral coordination by one tetradentate teta ligand and two bridging cyano groups as a trans position, whereas the Ni^II ion has square planer coordination and is coordinated by four cyano ligands. The decomposition reaction takes places in the temperature range 30–600 °C in the static air atmosphere.     

EPR Spectroscopy of 4, 4′‐Bis(tert‐butyl)‐2, 2′‐bipyridine‐1, 2‐dithiolatocuprates(II) in Host Lattices with Different Coordination Geometries

A series of new heteroleptic MN₂S₂ transition metal complexes with M = Cu²⁺ for EPR measurements and as diamagnetic hosts Ni²⁺, Zn²⁺, and Pd²⁺ were synthesized and characterized. The ligands are N₂ = 4, 4′‐bis(tert‐butyl)‐2, 2′‐bipyridine (tBu₂bpy) and S₂ =1, 2‐dithiooxalate, (dto), 1, 2‐dithiosquarate, (dtsq), maleonitrile‐1, 2‐dithiolate, or 1, 2‐dicyanoethene‐1, 2‐dithiolate, (mnt). The Cu^II complexes were studied by EPR in solution and as powders, diamagnetically diluted in the isostructural planar [Ni^II(tBu₂bpy)(S₂)] or[Pd^II(tBu₂bpy)(S₂)] as well as in tetrahedrally coordinated[Zn^II(tBu₂bpy)(S₂)] host structures to put steric stress on the coordination geometry of the central CuN₂S₂ unit. The spin density contributions for different geometries calculated from experimental parameters are compared with the electronic situation in the frontier orbital, namely in the semi‐occupied molecular orbital (SOMO) of the copper complex, derived from quantum chemical calculations on different levels (EHT and DFT). One of the hosts, [Ni^II(tBu₂bpy)(mnt)], is characterized by X‐ray structure analysis to prove the coordination geometry. The complex crystallizes in a square‐planar coordination mode in the monoclinic space group P2₁/a with Z = 4 and the unit cell parameters a = 10.4508(10) Å, b = 18.266(2) Å, c = 12.6566(12) Å, β = 112.095(7)°. Oxidation and reductions potentials of one of the host complexes, [Ni(tBu₂bpy)(mnt)], were obtained by cyclovoltammetric measurements.     

Cyano‐bridged Molecular Square: [Ni(iprtacn)Fe(phen)2(CN)2]2(PF6)4·6CH3CN – Preparation,Structure, Magnetic Properties and Binding with DNA

The cyano‐bridged molecular square Ni(iprtacn)]₂[Fe(phen)₂(CN)₂]₂(PF₆)₄ · 6CH₃CN ( 1 ) (iprtacn = 1,4,7‐triisopropyl‐1,4,7‐triazacyclononane, phen = 1, 10‐phenanthroline) was prepared and its crystal structure, magnetic properties, and binding with DNA were characterized. The four metal ions Ni^IIFe^IINi^IIFe^II of the complex 1 are almost coplanar. Magnetic susceptibilities measured over the range of 2–300 K show weak antiferromagnetic interactions between the two nickel(II) ions; best fitting for the experimental data leads to J = –1.27 cm^–1. UV/Vis and fluorescence spectra show that the complex is able to displace DNA‐bound EB and bind to DNA with strong interactions.     

Bis(1,2‐diselenoquadratato)metallate

Bis(1,2‐diselenosquarato) Metalates A series of 1,2‐diselenosquarato metalates [M(dssq)₂]^2– (M = Pd²⁺, Pt²⁺, Cu²⁺, Ni²⁺, Zn²⁺, Cd²⁺, Pb²⁺, VO²⁺) was available by direct synthesis from the appropriate metal salt with dipotassium 1,2‐diselenosquarate in deoxygenized water under an argon athmosphere. The copper(II)complex, [Cu(dssq)₂]^2–, and the oxovanadium(IV)complex, [VO(dssq)₂]^2–, were identified in solution by EPR spectroscopy (parameters: [Cu(dssq)₂]^2–: g₀ = 2.073; a = –76.0 · 10^–4 cm^–1, a = 47.0 · 10^–4 cm^–1; [VO(dssq)₂]^2–: g₀ = 1.986; a = 74.9 · 10^–4 cm^–1). The complexes bis(tetraphenylphosphonium)[bis(1,2‐diselenosquarato)nickelate(II)], (Ph₄P)₂[Ni(dssq)₂], and bis(tetraphenylphosphonium)[bis(1,2‐diselenosquarato)zincate(II)], (Ph₄P)₂[Zn(dssq)₂], were characterized by X‐ray structure analysis. The square‐planar Ni^II complex (Ph₄P)₂[Ni(dssq)₂] crystallizes in the monoclinic spacegroup P2₁/n with the unit cell parameters a = 11.1472(8) Å, b = 15.331(1) Å, c = 14.783(1) Å, β = 94.441(1)° and Z = 2. The Zn^II‐complex (Ph₄P)₂[Zn(dssq)₂] is tetrahedral coordinated and crystallizes in the monoclinic spacegroup P2₁/c with the unit cell parameters a = 9.4238(1) Å, b = 18.5823(3) Å, c = 29.5309(5) Å, β = 96.763(1)° and Z = 4.     

A new one‐dimensional nickel metal–organic framework: catena‐poly[[[diaquabis(4‐{[(1‐phenyl‐1H‐tetrazol‐5‐yl)sulfanyl]methyl}benzoato‐κO)nickel(II)]‐μ‐4,4′‐bipyridine‐κ2N:N′] monohydrate]

The title complex, {[Ni(C₁₅H₁₁N₄O₂S)₂(C₁₀H₈N₂)(H₂O)₂]·H₂O}_n, was synthesized by the reaction of nickel chloride, 4‐{[(1‐phenyl‐1H‐tetrazol‐5‐yl)sulfanyl]methyl}benzoic acid (HL) and 4,4′‐bipyridine (bpy) under hydrothermal conditions. The asymmetric unit contains two half Ni^II ions, each located on an inversion centre, two L⁻ ligands, one bpy ligand, two coordinated water molecules and one unligated water molecule. Each Ni^II centre is six‐coordinated by two monodentate carboxylate O atoms from two different L⁻ ligands, two pyridine N atoms from two different bpy ligands and two terminal water molecules, displaying a nearly ideal octahedral geometry. The Ni^II ions are bridged by 4,4′‐bipyridine ligands to afford a linear array, with an Ni...Ni separation of 11.361 (1) Å, which is further decorated by two monodentate L⁻ ligands trans to each other, resulting in a one‐dimensional fishbone‐like chain structure. These one‐dimensional fishbone‐like chains are further linked by O—H...O, O—H...N and C—H...O hydrogen bonds and π–π stacking interactions to form a three‐dimensional supramolecular architecture. The thermal stability of the title complex was investigated via thermogravimetric analysis.     

2‐Amino‐5‐(2‐pyridyl)‐thiadiazole as Bidentate Ligand

The amino substituted bidentate chelating ligand 2‐amino‐5‐(2‐pyridyl)‐1,3,4‐thiadiazole (H₂ L ) was used to prepare 3:1‐type coordination compounds of iron(II), cobalt(II) and nickel(II). In the iron(II) perchlorate complex [Fe^II(H₂ L )₃](ClO₄)₂·0.6MeOH·0.9H₂O a 1:1 mixture of mer and fac isomers is present whereas [Fe^II(H₂ L )₃](BF₄)₂·MeOH·H₂O, [Co^II(H₂ L )₃](ClO₄)₂·2H₂O and [Ni^II(H₂ L )₃](ClO₄)₂·MeOH·H₂O feature merely mer derivatives. Moessbauer spectroscopy and variable temperature magnetic measurements revealed the [Fe^II(H₂ L )₃]²⁺ complex core to exist in the low‐spin state, whereas the [Co^II(H₂ L )₃]²⁺ complex core resides in its high‐spin state, even at very low temperatures.     

A cyanide‐bridged heterometallic coordination polymer constructed from square‐planar [Ni(CN)4]2−: synthesis,crystal structure,thermal decomposition,electron paramagnetic resonance (EPR) spectrum and magnetic properties

Square‐planar complexes are commonly formed by transition metal ions having a d⁸ electron configuration. Planar cyanometallate anions have been used extensively as design elements in supramolecular coordination systems. In particular, square‐planar tetracyanometallate(II) ions, i.e. [M(CN)₄]²⁻ (M^II = Ni, Pd or Pt), are used as good building blocks for bimetallic Hofmann‐type assemblies and their analogues. Square‐planar tetracyanonickellate(II) complexes have been extensively developed with N‐donor groups as additional co‐ligands, but studies of these systems using O‐donor ligands are scarce. A new cyanide‐bridged Cu^II–Ni^II heterometallic compound, poly[[diaquatetra‐μ₂‐cyanido‐κ⁸C:N‐nickel(II)copper(II)] monohydrate], {[Cu^IINi^II(CN)₄(H₂O)₂]·H₂O}_n, has been synthesized and characterized by X‐ray single‐crystal diffraction analyses, vibrational spectroscopy (FT–IR), thermal analysis, electron paramagnetic resonance (EPR) and magnetic moment measurements. The structural analysis revealed that it has a two‐dimensional grid‐like structure built up of cationic [Cu(H₂O)₂]²⁺ and anionic [Ni(CN)₄]²⁻ units connected through bridging cyanide ligands. The overall three‐dimensional supramolecular network is expanded by a combination of interlayer O—H…N and intralayer O—H…O hydrogen‐bond interactions. The first decomposition reactions take place at 335 K under a static air atmosphere, which illustrates the existence of guest water molecules in the interlayer spaces. The electron paramagnetic resonance (EPR) spectrum confirms that the Cu^II cation has an axial coordination symmetry and that the unpaired electrons occupy the d orbital. In addition, magnetic investigations showed that antiferromagnetic interactions exist in the Cu^II atoms through the diamagnetic [Ni(CN)₄]²⁻ ion.     

Synthesis,Spectroscopic Properties,and Crystal Structure of 2,2′‐Bipyridyldimesitylnickel(II)

The dimesitylnickel(II) complex [(bpy)NiMes₂] (Mes = mesityl = 2,4,6‐trimethylphenyl) was prepared and examined spectroscopically and electrochemically. The crystal and molecular structure was determined from single crystal X‐Ray diffraction experiments (monoclinic, P2₁/n, Z = 4, a = 8.3092(8) Å, b = 18.233(2) Å, c = 15.226(2) Å, β = 98.035(6)°). The nickel atom displays a distorted square planar environment. The axial positions of the square plane are shielded by each one of the methyl groups on the mesityl substituents. The complex shows electrochemical reduction processes that are mainly centered on the bpy ligand as inferred from spectroelectrochemical investigations (EPR and UV/Vis/NIR absorption) of the radical anion or dianion. The observed oxidation is assigned to a Ni^II/Ni^III couple. The title complex exhibits strongly solvatochromic longwavelength electronic absorptions.     

Two Bulky Conjugated 4′‐(4‐Hydroxyphenyl)‐4,2′:6′,4′′‐terpyridine‐based Layered Complexes: Synthesis,Structure, and Photocatalytic Hydrogen Evolution Activity

Two new layered complexes with the formulas of {[Cu(H₂O)(HL)₂Cl](NO₃)}_n ( 1 ) and {[Cu(H₂O)₂(HL)₂](NO₃)₂}_n ( 2 ) were solvothermally synthesized by the reactions of the bulky conjugated 4′‐(4‐hydroxyphenyl)‐4,2′:6′,4′′‐terpyridine ligand (HL) with different Cu^II salts, which were further used as photocatalysts to achieve hydrogen production from water splitting. Single‐crystal structural analyses reveal that both complexes feature coplanar (4 4) layers with different connection manners between the HL extended Z‐shaped chains. More interestingly, 1 possessing more negative conduction band potential and higher structural stability exhibits a large hydrogen production rate of 2.43 mmol · g^–1 · h^–1, which is four times higher than that of 2 . Thus, the Cu^II‐based coordination polymers modified by the bulky conjugated organic ligand can become potentially promising non‐Pt photocatalysts for hydrogen production from water splitting.     

Hydrothermal Synthesis,Structure, and Magnetic Properties of a Three‐dimensional Polymeric NiII Complex, [Ni(bpp)(NIP)(H2O)]n (bpp = 1,3‐di(4‐pyridyl)propane,NIP = 5‐nitroisophthalate)

A three‐dimensional polymeric Ni^II complex, [Ni(bpp)(NIP)(H₂O)]_n (bpp = 1,3‐di(4‐pyridyl)propane and NIP = 5‐nitroisophthalate), has been synthesized and characterized. The coordination number of the nickel atom is six (NiN₂O₄) and the coordination environment around the Ni^II atom may be described as a distorted octahedron in which two nitrogen atoms of “bpp” ligand occupy the cis positions. The effective magnetic moment for this complex indicate that the interactions between two Ni^II atoms through the effective exchange media are antiferromagnetic. Self‐assembly of these compounds in the solid state via π–π‐stacking interactions is discussed.