Diverse architectures of hybrid materials induced by different mixed-ligands and applications in luminescence

For investigating the effects of different azacyclo-assisting ligands and O-donor bridging ligands on the structural construction, three different structural complexes, namely, {Zn(DBTA)(phen)(H₂O)}_n (1) (DBTA = 2, 5-Dibromo-terephthalic acid, phen = 1,10-Phenanthroline), [Zn(DBTA)(bimb)]_n (2) (bimb (1,4-bis(imidazole-1-ylmethyl)benzene) and {[Zn₂(bmimb)(PO₄)₂]·(H₂O)₂}_n (3) (bmimb = 1,2-bis(methylimidazole-1-ylmethyl) benzene) have been constructed by different mixed-ligands and Zn atoms. Their structures have been characterized by single-crystal X-ray diffraction analysis, elemental analysis, and Infrared spectroscopy. Complex 1 exhibits a common 2D layer with 4,4-connected topology. Complex 2 features an interesting 2-fold interpenetrating net with the aid of long-chain flexible azacyclo-assisting ligands. Complex 3 shows 3D supramolecular architecture with tetranuclear water cluster filling in the pores. Their fluorescence properties were also measured.     

Metal ions directed self-assembly based on rigid polycarboxylate ligand 5-tert-butyl isophthalic acid and flexible N-heterocyclic ligand 1,4-bis(2-methylimidazol-1-ylmethyl)-2,3,5,6-tetramethylbenzene

Two new complexes {[Cd(bmimx)_0.5(tbip)(H₂O)] · H₂O}_n (1) and [Zn(bmimx)(tbip)]_n (2) (bmimx = 1,4-bis(2-methylimidazol-1-ylmethyl)-2,3,5,6-tetramethylbenzene, H₂tbip = 5-tert-butyl isophthalic acid) based on mixed ligands have been hydrothermally synthesized by varying the metal ions. Structural analysis reveals that complex 1 displays a 2D layer structure with a 4⁴-sql topology; complex 2 exhibits a 3D 4-fold interpenetrated framework with sra topology. The structural differences between 1 and 2 indicate that metal ions have significant effects on the formation of the final architectures. In addition, the thermal stabilities and photoluminescent properties of the two complexes were also investigated.     

Pillar-layered Zn–triazolate–carboxylate frameworks tuned by the bend angles of ditopic ligands

In the utilization of three ditopic ligands with different bend angles as pillars, we reported herein three pillar-layered Zn–triazolate–carboxylate frameworks, namely, [Zn₂(ATRZ)₂(BDC)]_n (1), [Zn₂(ATRZ)₂(TPDC)]_n·2nDMF (2) and [Zn₂(ATRZ)₂(ADDC)]_n (3) (ATRZ = 3-amino-1,2,4-triazole, H₂BDC = 1,4-benzenedicarboxylic acid, H₂TPDC = 2,5-thiophenedicarboxylic acid, and H₂ADDC = 1,3-adamantanedicarboxylic acid). Single crystal structural analyses demonstrate that different geometries of ditopic carboxylate pillars not only result in Zn–ATRZ layers adopting various corrugated configurations, but also give rise to 3,4-connected self-interpenetrated net of 1 and non-interpenetrated nets of 2 and 3. All these compounds exhibit high thermal stability and blue photoluminescence.     

A series of lanthanide (III) coordination polymers derived via in situ hydrothermal decarboxylation of quinoline-2,3-dicarboxylic acid

A series of one-dimensional coordination polymers assembled from LnNO₃ · 6H₂O (Ln = Sm(1), Eu(2), Tb(3), La(4), Ce(5), Pr(6), Nd(7), Dy(8)), quinoline-2,3-dicarboxylic acid (2,3-H₂qldc) and 1,10-phenanthroline (phen) formulated as [Ln(2,3-qldc)(3-qlc)(phen)]_n (3-Hqlc = quinoline-3-carboxylic acid) were obtained under hydrothermal conditions. It is remarkable that in situ hydrothermal decarboxylation was observed during preparing these polymers. Complexes 1–8 were characterized by elemental analyses, IR spectroscopy and single crystal X-ray diffraction analyses. The thermal stabilities and photoluminescence properties of these complexes have been investigated.     

Structures and photoluminescence of coordination polymers assembled from bifunctional ligand containing both tetrazole and imidazole groups

Three new coordination polymers, namely, {[Cu₂(IPT)(SO₄)(OH)(H₂O)]·H₂O}_n (HIPT = 5-(4-(1H-imidazol-1-yl)phenyl)- 1H-tetrazolate, 1), {[Cd₂(IPT)(NPA)(OH)]·H₂O}_n (H₂NPA = 5-nitroisophthalic acid, 2), and {[Zn₂(IPT)(IDC)(H₂O)]·3H₂O}_n (H₃IDC = 1H-imidazole-4,5-dicarboxylic acid, 3), were assembled from a bifunctional organic ligand containing both tetrazole and imidazole groups with/without the aid of carboxylate coligands. Compound 1 possesses 2D structure built by 1D [Cu₂(IPT)(SO₄)(OH)]_n secondary building blocks and IPT⁻ linkers. The 2D networks are linked into 3D supramolecular framework via water chains in helical conformation. Compound 2 displays 3D pillar-layer framework with 2D layers based on tetranuclear Cd(II) SBUs and NPA^2 − pillars. Compound 3 exhibits a 3D framework constructed from the interconnection of 1D [Zn-IDC]_n chains and binuclear Zn₂(IPT)₂ rings. The thermal stabilities of porous compound 3 and luminescent properties of compounds 2 and 3 have also been studied in detail. They exhibit intense solid-state fluorescent emissions at room temperature.     

Synthesis of diiron sulfur clusters containing thiolato-1,8-naphthalene imide ligand

Three diiron sulfur clusters containing thiolato-1,8-naphthalene imide ligand, [Cp*Fe(μ-4,5-S₂-ⁿBu-NMI)(μ-CO)FeCp*] (3a), [Cp′Fe(μ-4,5-S₂-ⁿBu-NMI)(μ-CO)FeCp′] (3b), [CpFe(ⁿBu-NMI-S)]₂ (4) (3a: Cp* = η⁵-C₅Me₅; 3b: Cp′ = η⁵-C₅HMe₄; 4: Cp = η⁵-C₅H₅; ⁿBu-NMI = N-butyl-1,8-naphthalene imide) were synthesized via the reaction of N-butyl-4,5-disulfide-1,8-naphthalene imide and [Cp2Fe(μ-CO)CO]₂ (Cp2 = Cp*, Cp′, Cp). A partially desulfurated product [CpFe(ⁿBu-NMI-S)]₂ was determined in the reaction of [CpFe(μ-CO)CO]₂ with ⁿBu-NMI 4,5-dithiolate. The new complexes were structurally characterized by X-ray analysis.     

A series of novel indium complexes derived from aromatic carboxylic acids: Hydrothermal syntheses,crystal structures,supramolecular networks and fluorescent properties

Five new compounds with mixed-ligand formulated as (H₄bptc)(phen) (1), [In(phen)₂Cl₂](H₄bptc)(NO₃)(H₂O) (2), [In(Hbptc)(phen)(H₂O)]₂ (3), In(2,6-pydc)(phen)(H₂O)Cl (4), and {[In(2,6-pydc)(Ox)_0.5(H₂O)₂](H₂O)}₂ (5) have been synthesized under hydrothermal conditions. Compounds 1–5 display white, green and blue fluorescence at 298 K in the solid state, respectively. It is shown that 1 assumes solvent-dependent photoluminescence. By contrast, the different polarities of solvents do not alter the luminescence position of 3 and 5. The thermogravimetric curves show that binuclear compounds 3 and 5 have excellent thermal stability, whose structures are stable up to 190 and 272 °C, respectively.     

Synthesis,crystal structure and luminescence of novel two-dimensional interpenetrating frameworks

Two novel metal coordination polymers, [Zn(nic)(isonic)]_n (1) and [Cu(nic)(isonic)]_n (2) (H₂nic = nicotinic acid, H₂isonic = isonicotinic acid), have been hydrothermally synthesized and characterized by elemental analysis, IR, and single crystal X-ray diffraction. X-ray single-crystal structural analyses reveal that 1 and 2 are isomorphous, two-dimensional interpenetrating (4, 4) frameworks bridged by nic and isonic ligands, and further assembled into a three-dimensional supramolecular structure via π–π stacking interaction. Moreover, 1 displayed photoluminescent properties in the blue range at room temperature.     

Three new d10 coordination polymers based on 2-(2-pyridyl)benzimidazole ligand: Synthesis,structures and properties

Three coordination polymers containing 2-(2-pyridyl)benzimidazole (PyHBIm) ligand, namely {[Zn₃(PyBIm)₃(PyHBIm)₂(tma)(H₂O)]?H₂O}_n (1), [Zn(PyHBIm)(oba)]_n (2), [Cd(PyHBIm)(oba)]_n (3), (tma = trimesate, oba = 4,4′-oxybis-(benzoate)), have been prepared through hydrothermal reaction. Compound 1 exhibits one-dimensional (1D) helical structure. However, compounds 2 and 3 display 1D meso-helical structure. These 1D structures are further assembled into three-dimensional (3D) networks through aromatic π–π stacking interactions and hydrogen bonding interactions. Moreover they all exhibit strong photoluminescence at room temperature and may be good candidates for potential luminescence materials.     

Synthesis,structure and near-infrared (NIR) luminescence of three solvent-induced pseudo-polymorphic complexes from a bimetallic Zn–Nd Schiff-base molecular unit

Three solvent-induced pseudo-polymorphic bimetallic Zn–Nd complexes [ZnNdL(OAc)(NO₃)₂(DMF)] · solvate (solvate: MeCN (1), THF (2), EtOH (3); H₂L = N,N′-bis(3-methoxy-salicylidene)phenylene-1,2-diamine) were obtained, and their solid NIR luminescence related to the packing structure from the intermolecular π–π interactions was discussed.     

N-heterocyclic dithiocarbamate platinum(II) complexes: Unexpected transformation of dithiocarbamate to oxodithiocarbonate in phosphinoplatinum complexes in solution

[PtCl₂(dppe)] (dppe = 1,2-bis(diphenylphosphino)ethane) reacts with pyrazol-1-yl- (L1), 3,5-dimethylpyrazol-1-yl- (L2), and indazol-1-yl- (L3) dithiocarbamate to form [Pt(L1)₂(dppe)] (1), [Pt(L2)₂(dppe)] (2) and [Pt(L3)₂(dppe)] (3). These complexes readily transform into [Pt(S₂CO)(dppe)] (4) in chloroform and dichloromethane at room temperature. Stability of the bis(dithiocarbamate)platinum complex from L2, [Pt(L2)₂] (5) suggests that the transformation of 1–3 to 4 is facilitated by the phosphine ancillary ligand.     

Two novel lead-carboxylate complexes based on nicotinic acid N-oxide: Synthesis,crystal structures and luminescent properties

Two new lead-carboxylate complexes based on nicotinic acid N-oxide ligand, [Pb(NNO)(FA)_0.5] (1) (HNNO = nicotinic acid N-oxide, FA = fumaric acid) and [Pb₂(NNO)(BTC)] (2) (H₃BTC = 1,3,5-benzenetricarboxylic acid) were hydrothermally synthesized and characterized by the elemental analyses, IR spectra and single crystal X-ray diffraction. Significant phosphorescent properties of two compounds were observed at room temperature.     

Two new isomeric complexes containing a well-resolved 1D water morph and (6, 3)-connected framework through hydrogen bonding interactions

Two new isomeric complexes, namely {[Cu(fum)(tpy)] · 5H₂O}_n (1) and [Cu₂(fum)₂(tpy)₂] · 4H₂O (2), have been synthesized simultaneously from the reaction of Cu(fum) with tpy (where fum = fumarate, tpy = 2,2′:6′,2″-terpyridine) under mild condition. The crystal structures of complexes were determined by X-ray single-crystal diffraction. Complex 1 stabilizes in an unusual 1D water tape notated T4(2)10(2), which is directed by two chiral helical water chains; binuclear complex 2 represents a complicated (6, 3)-connected framework via supramolecular interactions. Additionally, complex 1 exhibits weak ferromagnetic behavior.     

The first lanthanide–tetraselenidoantimonate complexes with hexadentate polyamine co-ligand: Solvothermal syntheses of [Sm(peha)(SbSe4)]n and [Eu(peha)(SbSe4)]

Two lanthanide(III) complexes containing tetraselenidoantimonate ligand [Sm(peha)(μ-1κ²:2κ-SbSe₄)]_n (1), and [Eu(peha)(1κ²-SbSe₄)] (2) (peha = pentaethylenehexamine) were solvothermally prepared by reactions Sb, Se and LnCl₃ in pentaethylenehexamine (peha). The tetrahedral [SbSe₄]^3 − unit connects [Sm(peha)]^3 + into the neutral 1-D coordination polymer 1 as a tridentate μ-1κ²:2κ-SbSe4 bridging and chelating ligand. It coordinates to [Eu(peha)]^3 + with a 1κ²-SbSe₄ chelating mode, forming the mononuclear complex 2. The tridentate μ-1κ²:2κ-SbSe₄ bridging and chelating mode and 9-coordinate Sm(III) center in 1 are firstly observed in the systematic syntheses of the Sm/Sb/Se system in different polyethylenediamines. Compounds 1 and 2 exhibit steep band gaps at 2.04 and 2.11 eV at room temperature, respectively.     

A lead(II)-orotate coordination polymer with a new coordination mode: Synthesis,structure and luminescent property

A lead(II) orotate complex [Pb(HOr)(H₂O)]_n (1), (H₃Or = orotic acid) was synthesized under hydrothermal condition and characterized by X-ray diffraction, IR, solid-state photoluminescence and thermogravimetric analysis. Lead atom in 1 is in a holodirected eight-coordinated polyhedron and the orotate ligand exhibits a new and unique hexametallic coordination mode. The lead complex shows a 6,6-connected (4⁸, 6⁶, 8)(4¹³, 6²) topology. The complex exhibits photoluminescence at 546 nm (λ_ex = 350 nm).     

Temperature dependence of dual emission in ruthenium(II) complexes containing 3,3′-bi-1,2,4-triazine derivatives

Three new ruthenium(II) polypyridyl complexes with highly π-deficient ligands, [Ru(bpy)₂(btm)]²⁺ (1), [Ru(bpy)₂(btb)]²⁺ (2) and [Ru(bpy)₂(btp)]²⁺ (3) (bpy = 2,2′-bipyridine, btm = 3,3′-bis(5,6-dimethyl-1,2,4-triazine, btb = 3,3′-bis(5,6-diphenyl-1,2,4-triazine, btp = 3,3′-bis(phenanthro[9,10-e][1,2,4]triazine) were synthesized and characterized. Electrochemical data together with molecular calculations show that the first redox process in these complexes is not bpy based. Complexes 1, 2 and 3 display luminescence in ethanol/methanol (4/1, V/V) at 80 K, and all three complexes exhibit a temperature switch from single (150 K) to dual (80 K) emission behavior.     

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.     

Co-existence of heterometallic Zn2Er and ZnEr arrayed chromophores for the sensitization of near-infrared (NIR) luminescence

With the Zn-Schiff-base [ZnL(Py)] from the simple Salen-type Schiff-base ligand H₂L (H₂L = N,N′-bis(salicylidene)ethylene-1,2-diamine) as the precursor, two co-crystallized heterometallic (Zn₂Ln and ZnLn array) complexes [Zn₂Ln(L)₂(Py)₂(NO₃)₂]·[ZnLn(L)(Py)(NO₃)₃(H₂O)]·NO₃·mMeOH·nS (Ln = Er(1), S = CH₃CN, m = 2, n = 1 or Gd(2), S = H₂O, m = 1, n = 3) were obtained by the further reaction with Ln(NO₃)₃·6H₂O, respectively. The result of their photophysical properties shows the intramolecular effective energy transfer has been demonstrated in the Zn₂Er and ZnEr arrayed complex 1, and the co-existence of different chromophores should be a potentially new way to the fine-tuning properties of NIR luminescence from Er³⁺ ions.     

Two novel 2D organic–inorganic hybrid silicotungstates assembled by {Cu2Ln2(ox)(SiW11)2} dimers and [Cu(en)(ox)]/[Cu(en)2] linkers

Two novel 2-D organic–inorganic hybrid silicotungstates [H₂en][Cu(en)₂(H₂O)]₂{[Cu(en)₂]₃[Cu(en)(ox)]₂[Ln₂(ox)(α-SiW₁₁O₃₉)₂]}·nH₂O (Ln = Er^III, n = 10 for 1, Ln = Sm^III, n = 8 for 2) with mixed organic ligands of ox and en (ox = oxalate, en = ethylenediamine) have been hydrothermally synthesized and characterized by IR spectrum, thermogravimetric analysis (TGA), power X-ray diffraction (PXRD) and X-ray single-crystal diffraction, respectively. Notably, 1 and 2 are isomorphic and exhibit the first novel 2D organic–inorganic hybrid silicotungstates assembled by {Cu₂Ln₂(ox)(SiW₁₁)₂} dimers and [Cu(en)(ox)]/[Cu(en)₂] linkers. Furthermore, the TG curve of 1 and 2 display three steps of weight loss in the range of 25–1000 °C.     

Synthesis,structure, stability and DNA cleavage activities of three Cr(III) complexes with salicylate and ammonium ligands

Complexes [Cr(III)(SA)(en)₂]⁺ (1), [Cr(III)(SA)(DETA)(H₂O)]⁺ (2) and [Cr(III)(SA)(TETA)]⁺ (3) were synthesized (H₂SA = salicylic acid, en = ethylenediamine, DETA = diethylenetriamine, TETA = triethylenetetramine). Kinetics studies show that 2 is the most instable one among these complexes. In addition, only 2 is found to be a very efficient catalyst of the cleavage of PBR322 DNA in the absence of any added cofactor. The degradation rate from supercoiled form to nicked form was 1.05 ± 0.081 h^− 1 (10^− 5 M) at pH 7.4 and 37 °C. Thiobarbituric acid-reactive substances assay shows 2 fail to produce OH causing any degradation of deoxyribose ring even in the presence of ascorbic acid. Ethidium bromide displacement assay suggests that only 2 can kick out EB from the groove of DNA. The interaction with DNA causes a blue shift of the d → d transition spectra of 2.