A pair of nonporous homochiral cobalt-based coordination polymers for enantioselective recognition and electrocatalysis

A pair of nonporous enantiomers [Co(H₂O)(bpy)(L-Mand)]•H₂O•Cl (L-1) and [Co(H₂O)(bpy)(L-Mand)]•H₂O•Cl (D-1) (L-Mand = L-Mandelic acid, D-Mand = D-Mandelic acid, bpy = 4,4′-bipyridine) with 3D supermolecule framework possess excellent enantioselective recognition and electrocatalysis ability towards L- and/or D-tart.     

Six-, seven- and eight-coordinated Cd(II) ions with N-heterocyclic multicarboxylic acids

Two novel cadmium complexes [Cd₃(pta)₂(H₂O)₄]_n (1) (H₃pta = 2,4,6-pyridinetricarboxylic acid) and {[Cd(H₂pza)(H₂O)₂] · 2H₂O}_n (2) (H₄pza = 2,3,5,6-pyrazinetetracarboxylic acid) were synthesized. In both complexes, Cd(II) ions show three different coordination numbers of six and seven in 1 and eight in 2, respectively. Complex 1 displays a three-dimensional network structure and 2 shows a one-dimensional chain structure. The one-dimensional chains in 2 are vertical or parallel to each other and form a three-dimensional network structure by hydrogen bonds. In addition, 1 emits intense fluorescence on excitation of 342 nm.     

Two unusual copper complexes with nitrilotriacetate and 4,5-diazafluoren-9-one or trans-1,2-bis(4-pyridyl)ethylene mixed-ligands

Two unusual copper complexes [Cu(Hnta)(afo)] (1) and [Cu₃(nta)₂(bpe)₂(H₂O)₄] · bpe·10H₂O (2) were synthesized and characterized. 1 displays a novel zigzag chain structure via tetradentate Hnta ligands and 2 forms two-dimensional network via hydrogen bonds interactions between the coordination water molecules and nta or free bpe ligands.     

Syntheses and characterizations of two-dimensional polymers based on tetraimidazole tetraphenylethylene ligand with aggregation-induced emission property

Two new coordination polymers [Co(TIPE)(H₂O)₂]·Hbtc·CH₃CN·3H₂O (1) and [Cd(TIPE)_0.5(m-bdc)(H₂O)]·CH₃OH·H₂O (2) (TIPE = tetra(3-imidazoylphenyl)ethylene, H₃btc = 1,3,5-benzenetricarboxylate, m-H₂bdc = 1,3-benzenedicarboxylate) have been synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction, elemental analysis, IR, TGA, and PXRD. Furthermore, the luminescent properties of complexes 1, 2 and TIPE ligand have also been investigated in the solid at room temperature.     

Three-dimensional fivefold interpenetrating microporous metal–organic framework based on mixed flexible ligands

The chiral diamondoidlike Cd(II) containing coordination polymer {[Cd(oba)(bib)]·2H₂O}_n (1) (oba = 4,4′-oxybis(benzoate), bib = 1,4-bis(2-methyl-imidazol-1-yl)butane) is reported; the 3D networks interpenetrate fivefold, nevertheless leave cavities capable of including sizable guest molecules. This compound also exhibits high thermal stability and blue-shift emission, and can be explored for potential blue luminescent materials.     

Blue-green photoluminescent 5- and 10-connected metal 5-(4′-carboxy-phenyl)tetrazolate coordination polymers

Hydrothermal reaction of Zn/Cd salts, NaN₃ and 4-cyanobenzoic acid via in situ [2 + 3] cycloaddition generated two blue-green photoluminescent coordination polymers [Zn(cptta)(H₂O)] (1) and [Cd(cptta)(H₂O)] (2) (H₂cptta = 5-(4′-carboxy-phenyl)tetrazole). When only metal ions are considered as nodes, 1 shows rare 5-connected Shubnikov plane topological type and 2 has unprecedented 10-connected {3¹².4²⁴.5⁹} topological type.     

Assembly of one 2D layer and two 3D pillared-layer structures derived from metal ions and 5-(pyridin-4-yl)isophthalic acid with or without pillars

Three new coordination polymers, [Mn(L)(H₂O)₂]₂·5H₂O (1), [Cu(L)(4,4′-bipy)]₂·H₂O (2) and [Pb(L)(4,4′-bipy)_0.5] (3) (H₂L = 5-(pyridin-4-yl)isophthalic acid; 4,4′-bipy = 4,4′-bipyridine) have been synthesized and characterized by IR, thermogravimetric analysis, X-ray powder diffraction and X-ray single crystal diffraction. Complex 1 shows a 2D layer structure which stacks with the other ones to form 1D channels to hold 1D water chains. Complex 2 displays a 3D + 3D → 3D polycatenation network. 3 shows a unique 2D + 2D → 3D polycatenation net in which each Pb center has a hemidirected coordination geometry due to the existence of “inert pair effect”. The thermal and luminescent properties of 1–3 were also examined.     

Three d10 coordination polymers based on rigid ligands with flexible functional groups: Syntheses,structures and luminescence

Three coordination polymers, namely, {[Zn(L)(BPY)]·DMF·H₂O}_n (1), {[Zn(L)(TPY)]·0.5H₂BDC·H₂O}_n (2), {[Cd(L)(H₂O)₂]·DMF}_n (3), have been synthesized based on a rigid linear carboxylate ligand (H₂L = 2′,5′-dimethoxy-[1,1′:4′,1″-terphenyl]-4,4″-dicarboxylic acid) and different lengths of pyridine ligands (TPY = 4,3′:5′,4″-terpyridine; BPY = 4,4′-bipyridine). These complexes have been characterized by single crystal X-ray diffraction, infrared spectroscopy, thermogravimetry, elemental analysis, and powder X-ray diffraction measurements. Complex 1 is a 6-connected 3-fold interpenetrating pcu net with point symbol {4¹² ∙ 6³}, 2 and 3 can be simplified as 4-connected sql nets with point symbol {4⁴ ∙ 6²}. In addition, their photoluminescent properties are also investigated in detail.     

Solvent-free synthesis of new open-framework metal oxalates with different 4-connected topologies

Three open-framework metal oxalates, formulated as (Hdbu)[In₂(OH)(ox)₃] (1), (Hthfa)[Eu₂(Hthfa)(H₂O)(ox)₄]⋅ 3H₂O (2), and (Hepc)[Bi(ox)₂] (3), were prepared under solvent-free conditions, where dbu = 1,8-diazabicyclo[5.4.0]undec-7-ene, ox = oxalate, thfa = tetrahydrofurfurylamine, and epc = 4-ethylpiperazine-1-carbaldehyde. Topological analyses reveal that these compounds have different 4-connected networks with sra (for 1), lon (for 2), and dia (for 3) topologies. Compound 2 displays a bright red luminescence as a result of excitation at 397 nm.     

Three new coordination polymers based on 4-oxo-1(4H)quinolineacetate: Synthesis,structures and luminescent properties

Reactions of 4-oxo-1(4H)-quinolineacetic acid (Hoqa) and varied metal salts of Zn(II), Cd(II) and Ag(I) resulted in the formation of three new coordination polymers, namely, [Zn(oqa)₂]·H₂O (1), [Cd(bpy)(oqa)₂(H₂O)₂]·4H₂O (2) and [Ag(bpy)(oqa)]·2H₂O (3) (bpy = 4,4′-bipyridine). Complex 1 has a three-dimensional (3D) polymeric network with diamondoid topology; compounds 2–3 exhibit one-dimensional (1D) chain structure characteristics, which are further assembled through π–π stacking attractions and hydrogen bonds, forming the 3D supramolecular frameworks. In addition, the solid-state luminescent properties of the ligand Hoqa and complexes 1–2 have been investigated at room temperature.     

Novel heterobimetallic Cu/Mn coordination polymers prepared by “direct permanganate” synthesis

Two heterometallic Cu/Mn complexes [Cu(Me₂en)₂][Mn₂(ox)₃] · 2H₂O (1) (Me₂en = N,N-dimethylethylenediamine, H₂ox – oxalic acid) and [Cu(1,3-pn)(ox)(H₂O)][Mn(ox)(H₂O)₂] · H₂O (2) (1,3-pn = 1,3-diaminopropane) are prepared by the one-pot reaction of copper powder, tetrabutylammonium permanganate, oxalic acid and N-chelating ligands. Their structures are investigated by single-crystal X-ray analysis that reveals interesting variation in bridging motives of the oxalate groups composing the Mn-polymeric fragments.     

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.     

Two new luminescent Cd(II)/Zn(II) metal–organic frameworks for exceptionally selective detection of picric acid explosives

Two new coordination polymers, {[Cd(BIDPT)(oba)]·0.5H₂O}_n (1) and {[Zn(BIDPT)(4,4′-sdb)]·2.25H₂O}_n (2) (BIDPT = 4,4′-bis(imidazol-l-yl)diphenyl thioether, H₂oba = 4,4′-oxydibenzoic acid, 4,4′-H₂sdb = 4,4′-sulfonyldibenzoic acid), have been solvothermally synthesized and characterized. Both 1 and 2 show 2-fold interpenetrating 3D frameworks with {6⁵ ∙ 8} cds and {6⁶} dia topology, respectively. These two coordination polymers show strong luminescence and their luminescence could be quenched by a series of nitro explosives. Importantly, they exhibit very highly sensitive and selective detection of picric acid compared to other nitro explosives.     

An effective approach for constructing acentric heterometallic-organic framework with catalytic activity

A new acentric heterometallic–organic framework, [CdMg (btec)(DMF)(H₂O)₃] (1) (H₄btec = 1,2,4,5-benzene tetracarboxylic acid), has been solvothermally synthesized. It features a 4-connected net with typical pts topology. To the best of our knowledge, compound 1 is the first example of Cd–Mg heterometallic organic framework based on the H₄btec ligand. Compound 1 has potential unsaturated metal sites after the removal of coordination water molecules, so it shows good catalytic activity on the diethylzinc addition to benzaldehyde. The photoluminescent property of 1 is also investigated.     

Three cobalt (II) complexes with triethylenetetraaminehexaacetic acid: From binuclear complex to 3d-4f coordination polymers

The cobalt(II)–lanthanide(III) heteronuclear complexes [Ln(H₂O)₄Co₂(TTHA)(SCN)₂]·H₃O⁺ (H₆TTHA = triethylenetetraaminehexaacetic acid, Ln = La(2), Ce(3)) have been synthesized based on a binuclear building block of [Co₂(H₂TTHA)(H₂O)₂] in [Co₂(H₂TTHA)(H₂O)₂]·4H₂O (1). Single-crystal structures show that complex 1 is a binuclear complex, containing the [Co₂(H₂TTHA)(H₂O)₂] unit as a useful building block. Adding the La^3 + and Ce^3 + ions to this synthesis system, two new 3d-4f mixed complexes 2 and 3 were obtained. Complexes 2 and 3 show 3D framework, comprising an infinite 1D (one-dimensional) chain based on heterometallic Ln₂Co₂ (Ln = La(2), Ce(3)). Further investigations such as IR spectra, UV–vis spectra, TGA, XRD and magnetic properties were studied.     

Novel silver(I) compounds assembled from hybrid ligands based on linear or T-shaped coordination environment

Two novel 1D compounds {[Ag₃(Hbptc)(bpa)₂]·H₂O}_n (1) and [Ag₂(H₂bptc)(bpp)₂]_n (2) (H₄bptc = 3,3′,4,4′-benzophenonetetracarboxylic acid, bpa = 1,2-bis(4-pyridyl)ethane and bpp = 1,3-bis(4-pyridyl)propane) were synthesized and structurally characterized. The crystal structures of compounds exhibit two kinds of ladder-like chains based on linear or T-shaped coordination environment of Ag(I). Fluorescence spectra of compounds 1 and 2 indicate the unusual intensity of fluorescent emission upon photoexcitation which may be attributed to ligand-to-metal charge transfer and Ag–Ag interactions.     

Polycatenated (4, 4) lanthanide(III) coordination networks based on apidate: Synthesis,structure and properties

Three rare earth coordination polymers, {[Ln₂(μ₃-ADI)₂(μ₂-ADI)(H₂O)₄]·H₂O}_n (Ln = Tb, 1; Eu, 2; Er, 3; ADI = adipate), which show the inclined interpenetration of (4, 4) nets and bright luminescence, were isolated from H₂PDC-assisted (H₂PDC = pyridine-2,3-dicarboxylatic acid) hydrothermal reactions of H₂ADI and Ln₂O₃.     

A new 3D helical silver(I) cluster metal–organic framework with microporous structure and luminescent property

A new 3D helical silver(I) metal–organic polymer of {[Ag₂(ADC)(bib)_0.5]·H₂O}_n (1) (H₂ADC = 1,3-adamantanedicarboxylic acid, bib = 1,4-bis(2-methyl-imidazol-1-yl)butane), has been synthesized and characterized. Compound 1 exhibits significant void space that may be filled with guest H₂O molecules in spite of the metal-cluster that occurs in the solid. Preliminary thermal and fluorescence experiments show that compound 1 possesses strong fluorescent property and thermal stability, respectively.     

A luminescent europium metal–organic framework with free phenanthroline sites for highly selective and sensitive sensing of Cu2 + in aqueous solution

A luminescent europium metal–organic framework [Eu(HL)(L)(H₂O)₂]·2H₂O (1) (H₂L = (2,3-f)-pyrazino(1,10)phenanthroline-2,3-dicarboxylic acid) with uncoordinated phenanthroline nitrogen sites was hydrothermally synthesized. It exhibits highly sensitive and selective sensing of Cu^2 + in aqueous solution. To the best of our knowledge, complex 1 is the first luminescent Eu-MOF with uncoordinated phenanthroline nitrogen sites for selective sensing of Cu^2 + in aqueous solution. The probable sensing mechanism was discussed in detail.     

Hydrothermal syntheses,structures and luminescent properties of group IIB metal coordination polymers based on bifunctional 1H-tetrazolate-5-acetic acid ligand

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, tza^2? ligand adopts variable coordination modes: μ₃-κN3:κO1:κO2,N1 and μ₃-κN1:κN3:κO2 for 1, and μ₃-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 tza^2? ligand.