Guang-Bo Che

Syntheses, structures and photoluminescence of a series of metal-organic complexes with 1,3,5-benzenetricarboxylate and pyrazino[2,3-f][1,10]-phenanthroline ligands

A series of new metal-organic coordination complexes, [Co2(HBTC)2(Pyphen)2(H2O)4]·4H2O (1), [Mn(HBTC)(Pyphen)(H2O)] (2), [Cd2(OH)(BTC)(Pyphen)2]·H2O (3), [Cu2(OH)(BTC)(Pyphen)] (4), and [Zn2(OH)(BTC)(Pyphen)] (5) were prepared through hydrothermal reactions of pyrazino[2,3-f][1,10]-phenanthroline (Pyphen) and 1,3,5-benzenetricarboxylic acid (H3BTC) with different metal salts. All these compounds were structurally determined by X-ray single-crystal diffraction. In the dinuclear Co(II) compound (1) π–π interactions exist between Pyphen and HBTC2− ligands, resulting in interesting 2D supramolecular layers. For complex (2), the Mn(II) centers are linked by HBTC2− ligands to form a 2D (4,4) coordination layer, and these layers are interdigitated in pairs. Polymer (3) also possesses a 2D network structure composed of the tetrametallic clusters [Cd4(µ2-OH)2], which is extended to 3D arrays through the π–π interactions between Pyphen ligands. The isostructural coordination polymers (4) and (5) show the same 3D framework structure. Solid-state luminescent spectra of the Cd(II) and Zn(II) complexes indicate intense fluorescent emissions.

Synthesis, structure and characterization of two Cd(II) coordination polymers with helical structures

Two coordination polymers, [Cd2Cl2(1,3-BDC)(TTBT)(H2O)] (1) and [CdCl(1,4-HBDC)(TTBT)] (2) (1,3-BDC = 1,3-benzenedicarboxylate, 1,4-BDC = 1,4-benzenedicarboxylate, and TTBT = 10,11,12,13-tetrahydro-4,5,9,14-tetraaza-benzo[b]triphenylene), have been prepared under hydrothermal conditions and characterized by elemental analyses, IR spectra, thermal gravimetry (TG), fluorescence emission and single crystal X-ray diffraction analyses. The crystal structures were determined by X-ray diffraction and refined by full-matrix least-squares methods to R = 0.0621 and wR = 0.1543 using 4937 reflections with I > 2σ(I) for 1; and R = 0.0525 and wR = 0.1427 using 3386 reflections with I > 2σ(I) for 2. Compound 1 possesses a chiral chain structure. Adjacent chiral chains are further linked through π–π interactions between TTBT ligands to give a three-dimensional supramolecular architecture. Compound 2 displays a helical chain structure, with neighboring chains stacked by π–π interactions, generating an unusual three-dimensional supramolecular structure.

Solvothermal syntheses, structures, and luminescence of two heterometallic metal-organic frameworks constructed from m -BDC ( m -BDC = 1,3-benzene-dicarboxylate)

The reactions of m-H2BDC, NaOH with Cd(NO3)2 · 4H2O and Co(NO3)2 · 4H2O (m-BDC = 1,3-benzene-dicarboxylate) in DMF gave two isostructural three-dimensional (3D) heterometallic coordination polymers: [CdNa(m-BDC)2] · [NH2(CH3)2] (1) and [CoNa(m-BDC)2] · [NH2(CH3)2] (2), respectively. The compounds were characterized by single-crystal X-ray diffraction, X-ray powder diffraction, ICP, TGA, IR, and photoluminescence spectroscopy. The crystal structures were determined by X-ray diffraction and refined by full-matrix least-squares methods to R = 0.0221 and wR = 0.0579 using 1925 reflections with I > 2σ(I) for 1; and R = 0.0654 and wR = 0.1591 using 1881 reflections with I > 2σ(I) for 2. Their frameworks are constructed from M–O–C (M = Na, Cd and Co) chains composed of alternating six-coordinate Na(I) centers and four-coordinate Cd(II) or Co(II) centers. These chains are further linked by m-BDC to form unusual 3D open-framework structures.

Syntheses, crystal structures, and characterization of three metal–organic complexes with 2,2′-biphenyldicarboxylic acid and phenanthroline ligands

Three complexes constructed with 2,2′-biphenyldicarboxylic acid, multidentate nitrogen donors, and metal salts, {[Cd(2,2′-dpdc)(tppp)(H2O)]2 · 2H2O} n (1), {[Pb(2,2′-dpdc)(pyphen)]2} n (2), and {[Pb(2,2′-dpdc)(dppz)]} n (3) (H2dpdc = 2,2′-diphenyldicarboxylic acid; tppp = 4-(1H-1,3,7,8-tetraazacyclopenta[l]phenanthren-2-yl)phenol; pyphen = pyrazino[2,3-f]-[1,10]phenanthroline; and dppz = dipyrido[3,2-a:2′,3′-c]phenazine), are synthesized under hydrothermal conditions. These complexes are characterized by single-crystal X-ray diffraction, elemental analysis, IR, TGA, and photoluminescence. In 1, two 2,2′-dpdc ions bridge two Cd(II) ions to form an isolated cluster with Cd ··· Cd distance of 5.023(4) Å. These clusters are further linked by intermolecular hydrogen bonds, yielding a 2-D supramolecular structure. Complex 2 contains two crystallographically independent Pb(II) ions in the asymmetric unit. Pb1 ions are bridged by 2,2′-dpdc anions to form a chain along the x-axis. Two Pb2 ions are coordinated by two 2,2′-dpdc anions and two pyphen ligands to form a cluster. These clusters are linked by π–π interactions to yield a 1-D supramolecular chain along the y-axis. In 3, neighboring Pb(II) atoms are bridged by 2,2′-dpdc anions to form a 1-D chain structure. Further, the chains are linked into a 3-D supramolecular network through aromatic π–π interactions.

Bis[3,5-difluoro-2-(2-pyrid-yl)phen-yl](picolinato)iridium(III).

The Ir centre in the title complex, [Ir(C11H6F2N)2(C6H4NO2)], is six-coordinated in a slightly distorted octahedral IrC2N3O fashion.

A series of silver(I) coordination polymers of a new linear 4-((pyridin-4-ylthio)methyl)pyridine ligand: the role of organic and inorganic anions

Ten silver(I) coordination polymers {[Ag2(PTMP)2(L1)2]·3H2O}∞ (1), {[Ag2(PTMP)2(L2)]·7H2O}∞ (2), {[Ag2(PTMP)2(L3)]·2CH3OH}∞ (3), {[Ag2(PTMP)2(L4)]·5H2O}∞ (4), {[Ag(PTMP)]·0.5(L5)·2H2O}∞ (5), {[Ag(PTMP)(L6)0.5]·H2O}∞ (6), {[Ag3(PTMP)3(L7)]·2.25H2O}∞ (7), [Ag(PTMP)(NO3)]∞ (8), {[Ag(PTMP)]·(BF4)}∞ (9) and {[Ag(PTMP)]·(CF3SO3)·0.5H2O}∞ (10) derived from a new flexible 4-((pyridin-4-ylthio)methyl)pyridine ligand (abbreviated as PTMP) have been synthesized and fully characterized (L1 = pentafluoropropionate, L2 = malonate, L3 = 2,2,3,3,4,4-hexafluoropentanedioate, L4 = 1,4-cyclohexanedicarboxylate, L5 = 1,4-benzenedicarboxylate, L6 = 1,1′-biphenyl-4,4′-dicarboxylate and L7 = 2-hydroxypropane-1,2,3-tricarboxylate). These coordination polymers exhibit fascinating 1-D chains and 2-D and 3-D network structures with the PTMP functioning as a linear building block. Under a solvent medium with small van der Waals volume, the tuning effect of various anions from monocarboxylate to polycarboxylate (L1–L7) and the inorganic NO3−, BF4− and CF3SO3− on the construction of complexes 1–10 have been systematically investigated and discussed.

Syntheses and characterization of four coordination compounds derived from 10,11,12,13-tetrahydro-4,5,9,14-tetraaza-benzo[b]triphenylene and benzene-dicarboxylic acids

[Co2(TTBT)4(1,2-BDC)2] n  · 4nH2O (1), [Pb2(TTBT)2(1,3-BDC)2] n  · nTTBT · 2nH2O (2), [Fe(TTBT)(1,4-BDC)(H2O)] n (3), and [Zn(TTBT)(1,4-BDC)(H2O)] n (4) have been hydrothermally synthesized by self-assembly of TTBT (TTBT = 10,11,12,13-tetrahydro-4,5,9,14-tetraaza-benzo[b]triphenylene), benzene-dicarboxylic acid ligands 1,2-H2BDC, 1,3-H2BDC or 1,4-H2BDC (1,2-H2BDC = 1,2-benzenedicarboxylic acid, 1,3-H2BDC = 1,3-benzenedicarboxylic acid, 1,4-H2BDC = 1,4-benzenedicarboxylic acid), and various metal salts. Compound 1 has dinuclear cluster units, four dimeric Co2 units connected to form a 32-membered ring via weak offset π–π interactions, which are further stacked via strong π–π interactions to form a 3-D supramolecular framework. Complex 2 contains 2-D layers with rhombohedral grids, which are connected to a 3-D structure by π–π interactions. 3 and 4 feature 1-D infinite chains, which are further extended by strong π–π interactions and O–H···O hydrogen bonds resulting in 3-D supramolecular architectures. The photoluminescent properties of 2 and 4 have also been investigated.

Hydrothermal syntheses, structural characterization, and photoluminescent properties of five lanthanide coordination polymers

Five mixed-ligand coordination polymers, [Ln2(PTCP)2(m-BDC)3] n  · nH2O (Ln = Pr (1), Sm (2), Eu (3), Tb (4), Dy (5); m-BDC = 1,3-benzenedicarboxylate; PTCP = 2-phenyl-1H-1,3,7,8-tetraazacyclopenta[l]phenanthrene), were synthesized and characterized by IR spectra, elemental analyses, thermogravimetric analyses, single-crystal X-ray diffraction, and solid-state photoluminescent spectra. X-ray crystallographic analyses reveal that the five complexes are 1-D structures based on dinuclear [Ln2O12N4] units and further assembled into 3-D supramolecular networks by hydrogen bonds and π···π stacking interactions. The solids possess high thermal stabilities, with 3 and 4 exhibiting strong pure red and green characteristic emissions of Eu(III) and Tb(III) at room temperature.

Supramolecular helical nanofibers formed by an achiral monopyrrolotetrathiafulvalene derivative: water-triggered gelation and chiral evolution

Chiral nanostructures have attracted increasing attention, which would provide not only a better understanding of the bio self-assembly process, but also open a route for new applications. In this research study, the organogel formation and self-assembly of an achiral MPTTF-based molecule were investigated. It was found that the compound could not gelate any single solvent either through a heating and cooling process or by ultrasonic treatment, but formed certain ordered supramolecular self-assembled aggregates in pure DMF with left- (M) and right- (P) helicities. Interestingly, supramolecular gelation was triggered by adding a small amount of water in its DMF solution, and the structure of the fibers was almost entirely turned into right-handed helicity. The twisted superstructure was visualised by AFM, and CD was used to observe chirality within the assembly. Also, the investigation of UV-Vis spectra, FTIR and SAXS indicated that these supramolecular assemblies were induced by hydrogen bonding, π–π stacking and S⋯S interaction between the molecules. Furthermore, the formed organogel underwent a reversible gel–sol phase transition via a chemical redox reaction. This work sheds new light on the hierarchical transformation of chiral structures from achiral molecules by controlling the solvent composition and polarity.

catena-Poly[[aqua­(dipyrido[3,2-a:2′,3′-c]phenazine-κ2N4,N5)iron(II)]-μ-pyrazine-2,3-dicarboxyl­ato-κ3N1,O2:O3]

In the title compound, [Fe(C6H2N2O4)(C18H10N4)(H2O)]n, the FeII ion adopts a slightly distorted octahedral mer-FeN3O3 geometry, arising from one N,N′-bidentate dipyrido[3,2-a:2′,3′-c]phenazine ligand, one N,O-chelating pyrazine-2,3-dicarboxylate dianion and one water molecule. An O-bonded symmetry-related dianion completes the coordination of the metal. The bridging dianion results in a one-dimensional polymeric chain. Aromatic π–π stacking interactions between ligands [centroid–centroid separations = 3.528 (2) and 3.741 (2) Å] and O—H⋯O and O—H⋯N hydrogen bonds link the chains together, leading to a three-dimensional supramolecular network.