Guang-Ming Yang

Synthesis and magnetism of the first tetranuclear copper(II)–iron(III) complexes of macrocyclic oxamides

Abstract Four novel tetranuclear macrocyclic complexes of the formula [(CuLi)3Fe](ClO4)3·3H2O (i=1–4, Li are the dianions of the [14]N4 and [15]N4 macrocyclic oxamides, namely 2,3-dioxo-5,6:13,14-dibenzo-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene, 2,3-dioxo-5,6:13,14-dibenzo-9-methyl-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene and 2,3-dioxo-5,6:14,15-dibenzo-7,13-bis(ethoxycarbonyl)-1,4,8,12-tetraazacyclotetradeca-7,12-diene] have been prepared and characterized. These complexes are the first examples of oxamido-bridged Cu(II)–Fe(III) heterometallic species. Cryomagnetic studies on [(CuL1)3Fe](ClO4)3·3H2O (1) and [(CuL3)3Fe](ClO4)3·3H2O (3) (77–300 K) revealed that the Cu(II) and Fe(III) ions interact antiferromagnetically through the oxamido bridge, with the exchange integral J=−30.8 cm−1 for 1 and J=−28.7 cm−1 for 3 based on H =−2J ∑ S i S j . The interaction parameters have been compared with that of the related [Cu3Mn] compound.

A dinuclear cyano-bridged complex based on hexacyanoferrate(III) and samarium(III) nitrate : Synthesis and crystal structure

A new complex, [Sm(DMF)4(H2O)4Fe(CN)6]·H2O (DMF = N, N-dimethylformamide), has been synthesized and characterized by X-ray single crystal structure and thermogravimetric analyses. The complex crystallizes in the P21/n space group, with lattice parameters a = 17.583(4) Å, b = 8.870(2) Å, c = 19.845(6) Å, β = 95.98(3)°, V = 3078(1) Å3, Dx = 1.679 Mg m−3, Dm = 1.65(1) Mg m−3, Z = 4. The molecular structure shows that a cyano-bridged bimetallic structure is obtained. The Sm atom is coordinated by eight oxygen atoms of four water molecules and four DMF molecules and one nitrogen atom of the bridging cyanide ligand. The iron atom assumes approximately an octahedral environment surrounded by six CN ligands. The hydrate water molecule is hydrogen-bonded to one of the O atoms bound to Sm. Each terminal CN ligand of the Fe(CN)63− entity is hydrogen-bonded to some O atoms of water molecules. An infrared spectrum is also reported.

Magnetic properties of new copper(II) and [copper(II)]3-manganese(II) complexes of [14]N4 macrocyclic oxamides

Four new complexes of [14]N4 macrocyclic oxamides, namely [CuL1], [CuL2], [(CuL1)3Mn](ClO4)3 and [(CuL2)3 Mn](ClO4)3 [L1 and L2 are the dianions of 2,3-dioxo-5,6: 3,14-dibenzo-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene (H2L1) and 2,3-dioxo-5,6:13,14-dibenzo-9-methyl-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclo-tetradeca-7,11-diene (H2L2), respectively], have been prepared and characterized. The observed magnetic susceptibilities of the [(CuL1)3Mn] (ClO4)3 complex over the ca. 2–300 K range have been fitted to theoretical equations based on the Heisenberg spin Hamiltonian Ĥ=−2JŜMn(ŜCu1+ ŜCu2+ŜCu3) and molecular field approximation. The results indicated that both the intramolecular and intermolecular magnetic interactions are antiferromagnetic with JCuMn= −19.8cm−1 and zJ′=−1.41cm−1.

Synthesis, structure and magnetic properties of oxalate-bridged complex [Cu2(bpy)2(C2O4)(H2O2)][Cu(bpy)(C2O4)](NO3)2

Abstract The complex [Cu2(bpy)2(C2O4)(H2O)2][Cu(bpy)(C2O4)](NO3)2 has been synthesized by electrophilic attack of [Cu(bpy)(H2O)2]2+ on K3[Cr(C2O4)3] (where bpy stands for 2,2′-bipyridyl). The crystal structure of the complex consists of a binuclear species [Cu2(bpy)2(C2O4)(H2O)2]2+ and a mononuclear species [Cu(bpy) (H2O)(C2O4)]. The temperature dependences of the magnetic susceptibilities of the complex have been studied in the 4.2–300 K range, giving the exchange integral J = −340 cm−1, indicating rather strong antiferromagnetic interaction between the copper(II) ions within the binuclear unit.

Hydrolytic synthesis and structural characterization of five hexanuclear oxo-hydroxo lanthanide clusters

Five hexanuclear oxo-hydroxo lanthanide clusters are synthesized by hydrolysis of the lanthanide ions together with 4-amido-3,5-dimethyl-1,2,4-triazole (L). They all have a [Ln6(µ6–O)(µ3–OH)8]8+ core structure and the triazole groups stabilize the core structure in different fashions. The oxo group functions as an anion template to induce the self-assembly of lanthanide ions.

Novel oxalate-bridged trinuclear FeIII-MII-FeIII (M = Cu and VO) complexes: synthesis and magnetism

Two new heterotrinuclear FeIII-MII-FeIII oxalate-bridged complexes have been prepared, and characterized, namely MII[(ox)FeIII(Salen)]2, [Salen = N,N′-ethylenebis(salicylideneiminate), ox = oxalate, M = Cu (1) and VO (2)]. Based on elemental analysis, conductivity measurements and i.r. spectra, the complexes are proposed to have an oxalate-bridged structure. The magnetic susceptibilities of the complexes were measured over the 4.2–300 K range, giving the exchange integrals JAB = −4.23 cm−1, JAA = −2.47 cm−1 for (1) and JAB = −5.42 cm−1, JAA = −1.55 cm−1 for (2). These results revealed the operation of an antiferromagnetic spin-exchange interaction between the metal ions.

A Metal-Organic Framework Approach toward Highly Nitrogen-Doped Graphitic Carbon as a Metal-Free Photocatalyst for Hydrogen Evolution

Zeolitic imidazolate framework-8 (ZIF-8)-derived N-doped graphene analogous polyhedrons (ZNGs) obtained via the direct carbonation of ZIF-8 are applied to photocatalytic hydrogen evolution for the first time. The contents of different types of nitrogen atoms in ZNGs can be fine-tuned via the calcination temperature, which significantly influences the hydrogen evolution rate of the ZNGs.

Hydrothermal synthesis and crystal structure of oxamidato-bridged pentanuclear CuII4LaIII complex containing macrocyclic ligand

Abstract A novel oxamidato-bridge CuII4LaIII pentanuclear complex incorporating a macrocyclic oxamide of formula [(CuL)3(CuLC2H5OH)La(H2O)](ClO4)3·1.5H2O has been hydrothermally synthesized, spectroscopically, structurally, and magnetically characterized.

Synthesis, structure and magnetic properties of a quasi-one-dimensional copper(II) compound. An unusual oxalato-bridged copper dimer

Abstract A new compound [Cu(Him)2(ox)]2[Cu(Him)2(H2O)]2 (Him=imidazole, ox=dianion of oxalic acid) has been prepared and structurally determined. The structure consists of quasi-one-dimensional chains built from two different neutral [Cu(Him)2(ox)]2 and [Cu(Him)2(H2O)(ox)]2 units linked by hydrogen bonds. Two centrosymmetrically related copper ions in the former unit are five-coordinated by two nitrogen atoms from the imidazole ligands and two oxygen atoms from the oxalate anion occupying the basal plane and the oxygen atom of another chelating oxalate situated at the apical position with a weak contact of 2.837(2) A. The coordination environment of the other two copper ions connected by O–H · · · O hydrogen bonds in the other unit can be described as a distorted square pyramid, with two oxygen atoms of the oxalate ion and two nitrogen atoms from the imidazole ligands in the basal plane and one oxygen atom of the coordinated water molecule in the apical position. The (Him)N–H · · · O(ox) hydrogen bonds connect the adjacent units to give rise to a quasi-one-dimensional structure. The room-temperature ESR study gives a g↑ value of 2.07 and a g∥ value of 2.23. From magnetic susceptibility measurements the compound was found to exhibit a weak antiferromagnetic interaction (J=−2.64 cm−1) between the copper(II) ions through the Cu–O–Cu pathways.

A rhodamine-based fluorescent sensor for the highly selective and sensitive detection of mercury in aqueous solution and living cells

A novel Hg2+-selective fluorescent sensor (Sensor-Hg) based on a rhodamine scaffold, with N-Ethylthioethyl-N-[N′,N′-(2′-Diethylthioethylamino)-5′-methyl-Phenoxyethyl]-2-Methoxy Aniline (EDPMA) as a receptor, has been developed. Sensor-Hg exhibited ∼35-fold enhancement in fluorescence emission upon binding with Hg2+, with a characteristic emission band of rhodamine at ∼585 nm. It demonstrates high selectivity and sensitivity for detecting Hg2+ in aqueous solution and living cells.