Search

Abstract: Recently, the emergence of photoactive metal–organic frameworks (MOFs) has given great prospects for their applications as photocatalytic materials in visible‐light‐driven hydrogen evolution. Herein, a highly photoactive visible‐light‐driven material for H2 evolution was prepared by introducing methylthio terephthalate into a MOF lattice via solvent‐assisted ligand‐exchange method. Accordingly, a first methylthio‐functionalized porous MOF decorated with Pt co‐catalyst for efficient photocatalytic H2 evolution was achieved, which exhibited a high quantum yield (8.90 %) at 420 nm by use sacrificial triethanolamine. This hybrid material exhibited perfect H2 production rate as high as 3814.0 μmol g−1 h−1, which even is one order of magnitude higher than that of the state‐of‐the‐art Pt/MOF photocatalyst derived from aminoterephthalate. [ABSTRACT FROM AUTHOR]

An alternative approach to fabricate color-tunable and white-light-emitting lanthanide(iii) coordination polymers (LnCPs) is demonstrated by employing a selective light-emitting tetrazolate–dicarboxylate ligand, which displays different color emissions when coordinated to different lanthanide(iii) ions. The emission colour of the obtained LnCPs can be modulated from orange to white by simply adjusting the excitation wavelengths. White-light emissions, with high color rendering index and favorable correlated color temperature, have been successfully realized in new 2D single-component Sm(iii) and two-component Eu(iii)-doped Gd(iii) coordination polymers excited at specific excitation wavelengths. [ABSTRACT FROM AUTHOR]

Two new lead(ii) coordination polymers, [Pb(NO3)(tzib)]n (1) and [Pb(tzib)2]n (2), were successfully synthesized from the reaction of a rigid ligand 1-tetrazole-4-imidazole-benzene (Htzib) and lead(ii) nitrate in different solvents. The obtained polymers have been characterized by single-crystal X-ray diffraction analyses, which show that both polymers feature 2D layer structures. The inorganic anion nitrate in 1 shows a μ2–κO3:κO3 bridging mode to connect adjacent lead ions into a zigzag chain, and then the organic ligands tzib− join the neighboring chains into a 2D layer by a μ3–κN1:κN2:κN6 connection mode. In 2, there are two different bridging modes of the tzib− ligand: μ3–κN1:κN2:κN6 and μ3–κN1:κN6 to coordinate the lead ions into a 2D layer structure. Interestingly, both polymers displayed broadband emissions covering the entire visible spectra, which could be tunable to near white-light emission by varying excitation wavelengths. [ABSTRACT FROM AUTHOR]

A series of one-dimensional (1-D) N-succinopyridine-based complexes: [Cu(L−)(H2O)2]Cl·2H2O (1), [Pr(L−)(H2O)4]Cl2 (2), [Ln(L−)(H2O)5]Cl2·3H2O (Ln = Eu (3), Gd (4)), and [Er(L−)(H2O)4]Cl2·H2O (5) (HL = N-succinopyridine (−OOC–CH(N+C5H5)–CH2–COOH)) have been prepared and characterized by single-crystal X-ray diffraction. The frameworks of complexes 1, 2 and 5 constructed from dinuclear metal building blocks exhibit 1-D double-strand loop-like chains; these chains are further connected to each other by hydrogen bonds forming a 3-D supramolecular architecture. Whereas complexes 3 and 4 feature hydrogen bonding 2-D supramolecular networks assembled from 1-D chains that are constructed from mononuclear metal building blocks. The effects of different metal ions, steric hindrance and coordination diversities of HL on the polymeric architectures have been discussed. In addition, thermogravimetric and magnetic properties of these complexes were also investigated in this paper. [ABSTRACT FROM AUTHOR]

Abstract: Five new thiogermanates, [NiII(dien)2]2(Ge2S6) (dien=diethylenetriamine) (1), [NiII(dien)2](H2pipe)(Ge2S6) (pipe=piperazine) (2), {[MnII(tren)]2(μ 2-Ge2S6)} (tren=N,N,N-tris(2-aminoethyl)amine) (3) and {[MII(tepa)]2(μ 2-Ge2S6)} (M=Mn (4a), Ni (4b); tepa=tetraethylenepentamine), have been obtained solvothermally in the presence of tri-(L3), tetra-(L4) and penta-dentate (L5) chelating amines and transition metal (TM) ions. Single-crystal X-ray diffraction analyses show that compounds 1–2 are comprised of discrete (Ge2S6)4− anions and TM complex (TMC) cations, while compounds 3–4b are composed of each dimeric (Ge2S6)4− anion bridging two TMC cations via TM–S bonds to form a neutral molecule. Notably, two interesting in situ metal/ligand reactions were observed in the solvothermal syntheses of 2 and 3. The present compounds exhibit wide optical gap ranging from 2.94 to 3.39eV and photoluminescence with the emission maxima occurring around 440 (1, 2, 3 and 4b) and 489nm (4a). Magnetic measurements show the presence of weak antiferromagnetic interactions between magnetic centers in the five compounds. [ABSTRACT FROM AUTHOR]

Abstract: Assembly of isonicotinic acid ligand (HL) with metal halide, five new hybrid complexes [CdI2(C5H4NCOOH)(C5H4NHCOO)]·H2O (1), Na n [ZnCl2(C5H4NCOO)] n ·2nH2O (2), [CdX(C5H4NCOO)] n (X=Br (3), I (4)) and [Cd3Cl2(OH)2(C5H4NCOO)2] n (5) were obtained, which display a variety of structural motifs, ranging from zero-dimensional to complicated three-dimensional networks. Complex 1 possesses an isolated unit MX2 that is further connected into 3D networks through hydrogen bonding and π–π stacking interactions. Complex 2 is characterized by an infinite one-dimensional chain of zinc atoms bridged by L− ligands. While complexes 3 and 4 possess X-bridging inorganic chains connected by L− ligands to form a 2D hybrid network structure. In the case of 5, the cadmium(II) cation is bridged by μ3-Cl atom and μ3-OH− group to form a 2-D inorganic layer which is further extended into 3-D framework by bridging L− ligand via Cd–N and Cd–O bonds. The optical properties of 1, 4, and 5 in the solid state are investigated at room temperature and time-dependent DFT (TDDFT) calculation using the B3LYP functional has been performed on 1. The result indicated that the emission band of 1 is attributed to an admixture of MLCT (metal-to-ligand charge–transfer) and LLCT (ligand-to-ligand charge-transfer). [Copyright &y& Elsevier]

Abstract: Four triazole-bridging coordination complexes, [Zn4(ptr)2(SO4)3(μ 3-OH)2(H2O)4] n (1), [Hg(CN)2(ptr)] n (2), [Hg(Cl)2(ptr)] n (3), and [Cu2(μ 2-ptr)2(μ 2-F)2] n (SiF6) n ·2nH2O (4), were synthesized with (m-phenol)-1,2,4-triazole (ptr). Compounds 1–4 with extended structures of 4-substituted 1,2,4-triazole are rarely reported. The layered structure of 1 can be regarded as constructed from the 2-D inorganic backbone of SO4 2−(2) anions bridging [Zn4(μ 3-OH)2(H2O)2]6− subunits with the ptr ligands anchoring to both sides of backbone. Compounds 2 and 3 are the first mercury(II) complexes with 4-substituted 1,2,4-triazole, which feature the ptr ligand acting as a bidentate ligand bridging the Hg(II) atoms to form arciform –Hg–ptr–Hg–ptr chains. The structure of 4 is constructed from the F atoms bridging Cu atoms in symmetrical μ 2-coordination mode to form a zigzag cationic chain with each ptr ligand bridging a pair of Cu atom on the both sides, resulting in a nonplanar 5-membered [Cu2N2F] ring. Fluorescent properties of 1–4 were characterized and the magnetic property of 4 shows antiferromagnetic interaction between the copper(II) ions. [Copyright &y& Elsevier]

The first bulk electron-transfer photochromic compound with intrinsic second-order nonlinear optical (NLO) photoswitching properties has been synthesized. This system employs an electron-transfer photoactive asymmetric viologen ligand coordinated to a zinc(II) center. [ABSTRACT FROM AUTHOR]

Less attention has been paid to the solvent-dependent chirality transformation behavior of coordination compounds when using achiral precursors. We have successfully prepared one known helical achiral compound ( α -[AgL] n ∙ n H 2 O, 1 ) using water or DMSO as a solvent, one new helical homochiral MOF ( β -[AgL] n ∙ n H 2 O, 2 ) using DMF, dimethyl acetamide or ethanol as a solvent, and one new non-helical achiral compound ([Ag 2 L(NO 3 )] n , 3 ) using n -propyl alchohol or cyclohexanol as a solvent, with the V-shaped achiral ligand 3-aminobenzoic acid (HL) as a ligand. Achiral 1 can be converted from chiral isomeric 2 through recrystallization in water. Such successive chirality transformation (achirality → chirality → achirality) behavior is probably proportional the polarity of the used solvent: cyclohexanol ( 3 ) < n -propyl alchohol ( 3 ) < ethanol ( 2 ) < dimethyl acetamide ( 2 ) < DMF ( 2 ) < DMSO ( 1 ) < water ( 1 ). A preliminary study revealed that the isomeric compounds 1 and 2 displayed significantly different photoluminescence. [ABSTRACT FROM AUTHOR]

Abstract: Four homotrinuclear linear coordination compounds with bridging ligand of (m-phenol)-1,2,4-triazole, [Mn3(L)6(H2O)6](ClO4)6 (1), [Ni3(L)6(H2O)6](BF4)6·4DMF (2), [Cd3(L)6(H2O)6](ClO4)6· 2H2O·2DMF·2EtOH (3), [Zn3(L)8(H2O)4](BF4)4(SiF6)·2EtOH·12H2O (4), have been synthesized and structurally determined. The structures consist of three metal ions in linear arrangements, linked to each other by two pairs of three N1, N2 bridging triazole ligands. The negative value of J suggests that antiferromagnetic interaction exists in 1. Green fluorescence of 2 and 4 with emissions at 518nm for 2 and 524 for 4 is possibly assigned to LMCT. The energy gaps of the compounds 2 and 4 are 1.82 and 1.97eV, respectively, which suggests that the two materials behave as semiconductors. [Copyright &y& Elsevier]

Abstract: Reaction of the 2-D MOF [AgL] n ·nH2O (1; L=4-cyanobenzoate) with pyrazine (L′) in water yielded [Ag2L2L′] n ·2nH2O (2) with a chain-like structure. Compound 1 features tunable yellow-to-white photoluminescence when its wavelength of excitation light varies. The photoluminescence of 2 obviously differs from that of 1: the former displays intense yellowish green phosphorescence with a shorter lifetime of ~3.58μs and an unresolved peak shape, and does not exhibit tunable photoluminescence upon irradiation of 280–380nm UV light. Electron transition from the [Ag2(COO)2] cluster to pyrazine is probably responsible for the phosphorescence of 2 based on the experimental and theoretical results. [Copyright &y& Elsevier]

The pentadentate N4O amine-imine-naphthol ligand (HLD) containing rigid 8,16-imino-8H,16H-dinaphtho[2,1-b:2,1-f][1,5]dioxocin is formed preferentially, under visible light irradiation conditions, instead of the product H3L, expected from imidazolidine ring formation. A strained chelate bite enforces the first bridgehead nitrogen coordination to a copper(II) ion from the bicyclic iminodioxocin part of the ligand as shown by X-ray crystallography. [ABSTRACT FROM AUTHOR]

Abstract: We report a new non-interpenetrated 2D zinc coordination polymer, [Zn(AA)(BPHY)] n (1) (H2AA=adipic acid, BPHY=1,2-bis(4-pyridyl)hydrazine), which is a mixed ligand complex. The solid-state sample of 1 exhibits tunable blue emission excited by UV light with the wavelengths from 320nm to 380nm. The luminescent mechanism of 1 has been studied by theoretical calculation. [Copyright &y& Elsevier]

Abstract: Two polycatenated coordination polymers, {[Zn3(adc)3(bpp)4]2 ·3H2O} n (1) and [Zn(adc)(bphy)] n (2) (adc=azobenzene-4,4′- dicarboxylate, bpp=1,3-bis(4-pyridyl)propane, bphy=1,2-bis(4-pyridyl)hydrazine), have been obtained from Zn(NO3)2∙6H2O, linear H2adc ligand and arched bpp/azpy (azpy=4,4′-azobispyridine) ligands by hydro(solvo)thermal reactions. Compound 1 presents a 2-D structure catenated from 1-D double ladders (1-D→2-D polycatenation), while compound 2 displays a 3-D structure catenated from 2-D (4,4) stair-stepping layers (2-D→3-D polycatenation). Luminescence properties of 1 and 2 have been explored, together with study of photoluminescent mechanism by density of states (DOS) calculation. [Copyright &y& Elsevier]

Abstract: Hydrothermal reaction of NaN3, Na(4-cba) (4-Hcba = 4-cyanobenzoic acid) and ZnBr2 afforded a novel 3D Zn(II) coordination polymer [Zn2(4-tzba)2(H2O)]n 1 (4-H2tzba = 4-(5H-tetrazol)benzoic acid). In situ [2+3] cycloaddition reaction of nitrile and azide in the presence of ZnBr2 yielded tetrazolate-5-carboxylate 4-tzba2− ligand. Compound 1 displays an unprecedented four-connected topological network with 1D hexagonal channels constructed from trigonal rings [Zn3(4-tzba)6]. The solid-state photoluminescent studies revealed that 1 exhibits a strong blue emission mainly originating from 4-tzba2− ligand-centered charge transition. [Copyright &y& Elsevier]

Abstract: Hydrothermal reaction of diethyl 2-(2-cyanoethyl) malonate, ZnCl2, NaN3 and NaOH yielded a new 1H-tetrazolate-5-butyrate coordination polymer, [Zn(tzb)]n (1) (H2tzb=1H-tetrazolate-5-butyric acid), which presents a 3-D noninterpenetrating diamond network. The in situ generated tzb2− ligand adopts a μ4-bridging mode with carboxylate group in a syn–anti fashion and tetrazolate group in a 1,4-N manner. Polymer 1 exhibits a weak second-order nonlinear optical coefficient about 0.5 times that of potassium dihydrogen phosphate (KDP), and also displays strong blue photoluminescence at room temperature and a high thermal stability up to 400°C. [ABSTRACT FROM AUTHOR]

Abstract: A series of lanthanide(III) complexes with chelidamic acid ligand, [Ln(C7H2NO5)·3H2O] n ·nH2O (Ln=La (1), Y (2), Sm (3), and Nd (4)), [Gd2(C7H2NO5)3·4H2O] n ·2nH2O (5) and [Ce(C7H2NO5)·1.5H2O] n (6), have been synthesized by hydrothermal method and structurally characterized by single-crystal X-ray diffraction. Complexes 1–4 are isostructural and possess 2D framework. Complex 5 contains two different Gd(III) ions linked through carboxylate group to form a 2D framework. Complex 6 exhibits a (44) topology 2D network. The variable-temperature magnetic properties of 3 and 5 have been investigated. Furthermore, the photoluminescent properties of 1, 2, 3, and 5 at room temperature were also studied. [Copyright &y& Elsevier]

Abstract: Hydrothermal reaction of Cd(NO3)2, Co(NO3)2, Na(3-cba) and NaN3 yielded a 3D heterometallic coordination polymer, [Cd(μ5-3-tzba)(μ2-3-cba)(μ3-OH)Co(H2O)] n ·2nH2O 1 (3-H2tzba=3-(5H-tetrazol)benzoic acid and 3-Hcba=3-cyanobenzoic acid), which was characterized by single-crystal X-ray diffraction. The in situ [2+3] cycloaddition reaction of nitrile and azide in presence of Cd(II) salt afforded tetrazolate-based 3-tzba2− ligand. In 1, metal-oxo chains [Cd(μ3-OH)Co] n are linked by 3-tzba2− in an unprecedented μ5-κN1:κN2:κN3:κN4:κO1,O2 coordination mode to form 2D layers, which are further pillared by 3-cba− to generate a 3D open framework encapsulating 1D chiral channels. Variable-temperature magnetic studies show that 1 exhibits antiferromagnetic interactions between Co(II) ions bridged by μ3-OH group. [Copyright &y& Elsevier]

Abstract: Compared to previously reported methods, a less hazardous approach has been used to synthesize N-methylpyrazinium cation (mpz+) by the reaction of pyrazine and ClCH2COONa. Although a few mpz+-containing complexes have been documented, there is no example of mpz+-containing group IIB metal complexes. Three novel complexes containing mpz+, (mpz)ZnI3 (1), [(mpz)CdCl3] n (2), and [(mpz)CdBr3] n (3), have been successfully obtained via a solution or hydrothermal method by reactions of ZnI2, CdCl2·2.5H2O, and CdBr2·4H2O with the mpz+ ligand, respectively. Complex 1 features an isolated structure, with each zinc atom coordinated by one mpz+ ligand and three terminal iodine atoms. The CD spectra of 1 reveal that it exhibits spontaneous resolution. Complexes 2 and 3 are isotypic, and exhibit chain structures made by linear arrays of Cd(II) bridged by halogen atoms. Photoluminescent analyses reveal that complexes 1–3 exhibit strong blue emissions originating from intra-ligand π–π∗ transition of the mpz+ ligand. [Copyright &y& Elsevier]

Abstract: Hydrothermal reaction of 1H-tetrazolate-5-ethyl acetate (Htzea), MCl2 (M=Zn, Cd) and NaOH at different reaction temperatures produced three new coordination polymers: 2-D layered polymer [Zn(tza)(H2O)2] n 1, and 1-D chained supramolecular isomers 2 and 3 formulated as [Cd(tza)(H2O)2] n (H2tza=1H-tetrazolate-5-acetic acid), respectively. In these obtained polymers, tza2− ligand adopts variable coordination modes: μ 3-κN3:κO1:κO2,N1 and μ 3-κN1:κN3:κO2 for 1, and μ 3-κN2:κN1,O2:κO1,O2 for 2 and 3. The effects of reaction temperature and metal centers on the final polymeric frameworks have been discussed. Polymers 1–3 exhibit blue photoluminescence mainly arising from intraligand transitions of tetrazolate rings in tza2− ligand. [Copyright &y& Elsevier]

A 3-D metal-organic framework [Cd(BPHY)(SA)] n 1 (BPHY = 1,2-bis(4-pyridyl)hydrazine, H 2 SA = succinic acid) has been solvothermally synthesized. Compound 1 features a 2-fold pillar-layered structure and crystallizes in a non-centrosymmetric space group ( I 2). It is testified to be second harmonic generation (SHG) active. The blue photoluminescence of 1 is attributed to BPHY-centered charge transition demonstrated by theoretical calculation. [ABSTRACT FROM AUTHOR]

Abstract: A 1D coordination polymer, {[Cu3(C7H2NO5)2(H2O)7]·2(H2O)} n (1), has been synthesized and characterized by X-ray single-crystal diffraction. The crystal structure of 1 features that distorted square–pyramidal coordination polyhedra composed of Cu atoms and chelidamic acid ligands are interlinked into a 1D polymer, further linked by hydrogen bonds into a 3D network. The optical properties were investigated in terms of diffuse reflectance and fluorescent spectra, which exhibit strong luminescence. The electronic band structure along with the density of states (DOSs) calculated by the DFT method indicate that compound 1 pose an energy band gap of 1.89eV and that the origin of the emission band may be mainly ascribed to metal-to-ligand charge transfer (MLCT) where the electrons are transferred from the Cu-3d to O-2p and C-2p states. [Copyright &y& Elsevier]

Abstract: A large family of crystalline compounds with silver acetylenediide (Ag2C2) as a component have been synthesized and characterized. In most cases the C2 2− species is enclosed in a silver(I) polyhedron of 6–10 vertices, which may be symbolized as C2@Ag n (n =6–10). In the present review, emphasis is laid on our systematic studies in the controlled generation and supramolecular assembly of C2@Ag n polyhedra to form discrete molecules and higher-dimensional aggregates with the aid of co-existing anions and ancillary ligands. [Copyright &y& Elsevier]

Abstract: Two silver(I) complexes, [Mg(H2O)6][Ag2(HL)2] (1) and Sr2Ag4(HL)(H2O)14 ·2H2O (2) (H3L=5-sulfo-salicylic acid), have been synthesized by use of alkaline-earth metals (Mg2+ and Sr2+, respectively) as templates. Single-crystal X-ray diffractions reveal that compound 1 is a 1-D chain polymer built from [Ag2(HL)2] dimers and compound 2 is a 2-D framework constructed from unusual tetramer units of [Ag2(HL)2] dimers. The two complexes are both further linked into 3-D networks by the extensive intermolecular hydrogen bonding interactions. [Copyright &y& Elsevier]

Abstract: Three new zinc coordination polymers [Zn2(btc)2(H2O)2] n ·n[Zn(H2O)6] (1), [Zn3(btc)2(2,2′-bipy)2(H2O)3] n ·2nH2O (2) and [Zn3(btc)2(H2O)6] n ·nH2O (3) (H3btc=1,2,4-benzenetricarboxylic acid, 2,2′-bipy=2,2′-bipyridine) were obtained by the diffusion method and their crystal structures were determined by single-crystal X-ray diffraction. Compounds 1–3 have the similar tetrametallic unit [Zn4(btc)2] SBUs and these SBUs are further connected into stair-like structure, 2-D layer and 3-D framework for 1, 2 and 3, in which the btc3− ligands adopt μ 3, μ 4 and μ 5 coordination modes, respectively. The title compounds show strong blue fluorescence, which may be assigned as π*→n transition of the ligand mixed with the ligand-to-metal change transfer (LMCT), indicating the fluorescence, indicates the title compounds may be good candidates for blue-light photoactive materials. [Copyright &y& Elsevier]

A new dinuclear oxomolybdate complex [(C6H4OCHN(CH2)3NHCOC6H4)2Mo2O3]·2H2O was obtained as black needle crystals by the reaction of MoCl3·3H2O with a specially designed tetradentate Schiff base ligand under solvothermal conditions. Single-crystal X-ray diffraction analysis indicates that it crystallizes in a monoclinic P21/c space group with a rare oxo-bridged dinuclear molybdenum structure. The structure is characterized by two MoO4N2 octahedra sharing a corner oxygen atom in a completely linear Mo&z.sbnd;O&z.sbnd;Mo arrangement. In addition to being the first example of nearly linear O&z.sbnd;Mo&z.sbnd;O&z.sbnd;Mo&z.sbnd;O arrangements, the present structure features a Mo&z.sbnd;O single bond at two ends, in sharp contrast with the known O&z.dbnd6;M&z.sbnd;O&z.sbnd;M&z.dbnd6;O (M=W, Re) units that contain M&z.dbnd6;O double bonds for terminal oxygen, due to the spatial chelating requirement of the long tetradentate Schiff base ligand. The completely linear Mo&z.sbnd;O&z.sbnd;Mo structure together with the relatively short Mo&z.sbnd;O distance of 1.8819(7) A˚ suggests the involvement of metal–oxygen π bonding. [Copyright &y& Elsevier]