Synthesis, characterization and properties of some metal(II) 5-(nicotinamido)isophthalate complexes

Four new complexes, {[M(NAIP)(H₂O)₄]·2H₂O}_n (M = Co (1), M = Mn (2)), {[Zn(NAIP)]·0.5H₂O}_n (3) and {Cd(NAIP)(H₂O)₂]·1.5H₂O}_n (4) [H₂NAIP = 5-(nicotinamido)-isophthalic acid] have been prepared and structurally characterized. The ligand NAIP²⁻ exhibits different coordination modes and leads to the formation of various architectures. Complexes 1 and 2 show a one-dimensional (1D) zigzag chain, where hydrogen-bonding interactions further link these chains to a three dimensional (3D) supramolecular structure. For complex 3, a 3D coordination network with a four-coordinated Zn(II) and NAIP²⁻ as a SBU was observed. Complex 4 presents a three-connected 2-fold interpenetrated 3D network with a (10, 3)-b net topology. Their luminescent and magnetic properties have been investigated in the solid state.     

Syntheses,crystal structures,and magnetic and luminescent properties of a series of lanthanide coordination polymers with chelidamic acid ligand

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.     

Modelling the use of lanthanides(III) as probes at calcium(II) binding sites in biological systems: Preparation and characterization of neodymium(III) and calcium(II) malonamato(-1) complexes

A bioinorganic approach into the problem of the isomorphous substitution of calcium(II) by lanthanide(III) ions in biological systems is discussed. Reactions of malonamic acid (H₂malm) with Ca^II and Nd^III sources under similar conditions yielded the compounds [Ca(Hmalm)₂]_n (1), [Nd(Hmalm)₂(H₂O)₂]_n(NO₃)_n (2) and [Nd(Hmalm)₂(H₂O)₂]_nCl_n·2nH₂O (3·2nH₂O). Their X-ray crystal structure data show that the malonamate(-1) ligand presents two different ligation modes and coordinates through the two carboxylate and the amide-O atoms, thus bridging three Ca^II ions in 1 and two Nd^III ions in 2 and 3·2nH₂O. Complex 1 is a 3D coordination polymer based on neutral repeating units, whereas 2 and 3·2nH₂O are 1D coordination polymers based on the same cationic repeating unit. Hydrogen bonding interactions further stabilize the 3D framework structure of 1 and assemble the 1D chains of 2 and 3·2nH₂O into 3D networks. The three complexes were characterized spectroscopically (IR, far-IR, and Raman) and the thermal decomposition of 2 and 3·2nH₂O was monitored by TG/DTA and TG/DTG measurements. Variable-temperature magnetic susceptibility data for 2 are also reported. The bioinorganic chemistry relevance of our results is discussed.     

Chiral self-assembly of triorganotin complexes: Syntheses, characterization, crystal structures and antitumor activity of organotin(IV) complexes containing (R)-(+)-methylsuccinic acid, (S)-(+)-methylglutaric acid and l-(−)-malic acid ligands

Six new chiral triorganotin(IV) complexes, {(R₃Sn)₂[C₃H₆(COO)₂]}_n (R = Me: 1; Bu: 2), {(R₃Sn)₂[C₄H₈(COO)₂]}_n (R = Me: 3; Bu: 4), and {(R₃Sn)₂[C₂H₄O(COO)₂]}_n (R = Me: 5; Bu: 6) have been prepared by treatment of (R)-(+)-methylsuccinic acid, (S)-(+)-methylglutaric acid and l-(−)-malic acid, with the corresponding R₃SnCl (R = Me, Bu) and sodium ethoxide in methanol. All the complexes were characterized by elemental analysis, FT-IR, NMR (¹H, ¹³C, ¹¹⁹Sn) spectroscopy and TGA. Except for 3, all of the complexes were also characterized by X-ray crystallography. The structural analyses reveal that complexes 1 and 5 have 2D network structures in which (R)-(+)-methylsuccinic acid and l-(−)-malic acid act as tetradentate ligands coordinated to trimethyltin(IV) ions. Complexes 2 and 4 have 3D metal-organic framework structures in which the deprotoned acids serve as tetradentate ligands. Complex 6 adopts a 1D zigzag chain structure and forms a 2D supramolecular framework through intermolecular C-H?O interactions. In addition, the antitumor activities of complexes 1-6 have been studied. We also have measured the specific rotation of the chiral dicarboxylic acids and the organotin derivatives.     

A series of 2D lanthanide (III) coordination polymers constructed from 2-(pyridin-3-yl)-1H-imidazole-4,5-dicarboxylate

Reactions of 2-(pyridine-3-yl)-1H-4,5-imidazoledicarboxylic acid (H₃PyIDC) with a series of Ln(III) ions affords ten coordination polymers, namely, {[Ln(H₂PyIDC)(HPyIDC)(H₂O)₂]·H₂O}_n [Ln=Nd (1), Sm (2), Eu (3) and Gd (4)], {[Ln(HPyIDC)(H₂O)₃]·(H₂PyIDC)·H₂O}_n [Ln=Gd (5), Tb (6), Dy (7), Ho (8) and Er (9)], and {[Y₂(HPyIDC)₂(H₂O)₅]·(bpy)·(NO₃)₂·3H₂O}_n (10) (bpy=4,4′-bipyridine). They exhibit three types of networks: complexes 1-4 are isomorphous coordination networks containing neutral 2D metal-organic layers, while complexes 5-9 are isomorphous, which consist of cationic metal-organic layers and anionic organic layers, and complex 10 is a 2D network built up from 4-connected HPyIDC²⁻ anion and 4-connected Y(III) ions. In addition, thermogravimetric analyses and solid-state luminescent properties of the selected complexes are investigated. They exhibit intense, characteristic emissions in the visible region at room temperature.     

Synthesis, structures, luminescent and magnetic properties of four coordination polymers with the flexible 1,3-phenylenediacetate ligands

Four coordination polymers, [Zn(pda)(bpy)(H₂O)]_n·nH₂O (1), [Cd(pda)(prz)(H₂O)]_n (2), [Co₃(μ₃-OH)₂(pda)₂(pyz)]_n·2nH₂O (3) and [Pr₂(pda)₃(H₂O)₂]_n (4) (H₂pda=1,3-phenylendiacetic acid, bpy=4,4′-bipyridine, prz=piperazine and pyz=pyrazine) have been hydrothermally synthesized and characterized. Complex 1 is a 1D wheel-like chain structure, which is further extended into a 3D metal-organic supramolecular framework by H-bonds and π-π stacking interactions. Complex 2 is a 1D ladder-like chain structure, which is also further extended into a 3D metal-organic supramolecular framework by H-bonds. Complex 3 possess a 2D sheet structure with infrequent two pairs of double-helix chains. Complex 4 features a 3D structure. Both 1 and 2 display strong blue fluorescent emission at room temperature. Magnetic susceptibility measurements of complexes 3 and 4 exhibit antiferromagnetic interactions between the nearest metal ions, with C=9.99 and 3.43 cm³ mol⁻¹ K, and θ=−23.9 and −46.3 K, respectively.     

Influence of the anion on the coordination mode of an unsymmetrical N-heterocyclic ligand in Cd(II) complexes: From discrete molecule to one- and two-dimensional structures

Five new 0D–2D Cd(II) complexes, [Cd₂(Hbimt)₂I₄] (1), [Cd(bimt)(Hbimt)Br]_n (2), [Cd(Hbimt)Cl₂(H₂O)]_n (3), {[Cd(Hbimt)(SO₄)(H₂O)₂]·1.5H₂O}_n (4) and [Cd(Hbimt)(SCN)₂]_n (5) (Hbimt = 2-((benzoimidazol-yl)methyl)-1H-tetrazole) have been synthesized by the reactions of Hbimt with suitable cadmium salts. Employment of different anions can influence the coordination modes of the Hbimt ligand, and accordingly result in different structures ranging from 0D to infinite 1D and 2D networks. Complex 1 displays a dimeric structure in which two Cd(II) ions are bridged through two iodine atoms. Complex 2 was caused by deprotonation of the Hbimt ligand, resulting in a 1D helical chain. While in complexes 3 and 4, Hbimt acts as a bidentate bridging ligand which joins two Cd(II) ions, leading to 1D stair-like chains. Complex 5 exhibits a 2D network structure with infinite 1D [Cd₂(SCN)₂]_n chains. The distinct structures of 1, 2, 3, 4 and 5 reveal that the anions and the versatile coordination modes of the ligand play an important role in the structures of the complexes. In addition, the luminescent properties of complexes 1–5 have been investigated in the solid state at room temperature.     

Syntheses,topological networks and properties of four complexes based on 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole ligand

Reactions of metal acetates with 4-amino-3,5-bis(3-pyridyl)-1,2,4-triazole (3-abpt) and co-ligands gave rise to four new complexes, namely [Zn₂(3-abpt)(beta)(DMF) (H₂O)₂]_n·nH₂O (1), [Zn(3-abpt)(ip)]_n·3nH₂O (2), [Zn(3-abpt)(ip)(H₂O)₂]_n·2nH₂O (3), and [Cu₂(3-abpt)₂(C₆H₅COO)₄(H₂O)₂]_n·2nH₂O (4) (ip = isophthalate, beta = 1,2,4,5-benzenetetracarboxylate). Compound 1 is a 3D coordination polymer with uncommon 3,4-connected (6².8)₂(6².8².10²) network. Compounds 2–4 are all 1D coordination polymers, which exhibit diversity structures. Compound 2 is a tubular-like chain, 3 is a ring-like network, and 4 is a zigzag chain. Their thermal stabilities and the photoluminescence of 1 have also been investigated.     

Syntheses and characterization of inorganic–organic hybrids with 4-(isonicotinamido)phthalate and some divalent metal centers

Four new inorganic–organic hybrid frameworks [Mn(L)(H₂O)₂]_n (1), {[Co(L)(H₂O)₃]·2H₂O·CH₃OH}_n (2), {[Zn(L)(H₂O)]·H₂O}_n (3) and [Cd(HL)₂]_n (4) [H₂L = 4-(isonicotinamido)phthalic acid] have been synthesized and characterized by single-crystal X-ray diffraction analysis. Complex 1 has three-dimensional (3D) structure and topology related to SrAl₂ (sra) with Schläfli symbol of (4²·6³·8). And 2 displays (3,3)-connected two-dimensional (2D) network with (4,8²) topology, while 3 exhibits a uninodal (3,3)-connected (6,3) 2D network, which is further linked by N–H?O hydrogen bonding interactions to give 3D structure with hms topology and Schläfli symbol of (6³)(6⁹·8). Complex 4 with partial deprotonated HL⁻ ligands also has a 2D network structure. In addition, the magnetic property of 1, nonlinear optical property of 3 and photoluminescence of 3 and 4 were investigated.     

Coordination polymers with the chiral ligand N-p-tolylsulfonyl-l-glutamic acid: Influence of metal ions and different bipyridine ligands on structural chirality

Four new polymers, namely [Ni(-tsgluO)(2,4′-bipy)₂(H₂O)₂]_n·5nH₂O (1), [Co(-tsgluO)(2,4′-bipy)₂(H₂O)₂]_n·5nH₂O (2), [Ni(-tsgluO)(4,4′-bipy)]_n·0.5nH₂O (3), and [Co(-tsgluO)(4,4′-bipy)]_n·0.5nH₂O (4), where tsgluO²⁻=(+)-N-p-tolylsulfonyl-l-glutamate dianion, 2,4′-bipy=2,4′-bipyridine, and 4,4′-bipy=4,4'-bipyridine, have been prepared and structurally characterized. Compounds 1 and 2 are isostructural and mononuclear, and crystallize in the acentric monoclinic space group Cc, forming 1D chain structures. Compound 3 is also mononuclear, but crystallizes in the chiral space group P2₁, forming a homochiral 2D architecture. In contrast to the other complexes, compound 4 crystallizes in the space group P−1 and is composed of binuclear [Co₂O₆N₂]_n⁴⁻ units, which give rise to a 2D bilayer framework. Moreover, compounds 1, 2, and 4 self-assemble to form 3D supramolecular structures through π-π stacking and hydrogen-bonding interactions, while compound 3 is further hydrogen-bonded to form 3D frameworks. We have demonstrated the influence of the central metal and bipyridine ligands on the framework chirality of the coordination complexes.     

Syntheses,structures, photoluminescences of silver(I) coordination polymers with 2-aminopyrazine and varied dicarboxylate ligands

Four new silver(I) coordination polymers, namely [Ag(NH₂pyz)(ox)_0.5]_n (1), [Ag(NH₂pyz)(adp)_0.5·2H₂O]_n (2), [Ag₂(NH₂pyz)₂(bdc)·H₂O]_n (3) and [Ag₂(NH₂pyz)_2.5(ndc)]_n (4) [NH₂pyz = 2-aminopyrazine, ox = oxalate anion, adp = adipate anion, bdc = 1,4-benzenedicarboxylate anion, ndc = 1,4-naphthalenedicarboxylate anion] have been synthesized by solution phase ultrasonic reactions of Ag₂O with heterocyclic NH₂pyz and various dicarboxylates under ammoniacal conditions. The complexes were characterized by elemental analyses, IR spectra and single-crystal X-ray diffraction. Complex 1 is a three-dimensional (3D) framework with an α-ThSi₂ topology. Complex 2 features a 2D 4⁴-sql net involving infinite 1D double Ag-NH₂pyz chains and flexible adp anion spacers. Complex 3 is a 3D framework in which 1D single Ag-NH₂pyz chains are pillared by bdc anions to form a 2D 6³-hcb network, adjacent 2D networks are packed into a 3D framework through bridging O atoms of dbc anions. Complex 4 is a 2D structure built from infinite 1D stair-like chains containing finite Ag₄(NH₂pyz)₅ subunits. The results show that the structural diversity of the complexes result from the nature of the dicarboxylate ligands. The photoluminescence properties of the complexes were also investigated in the solid state at room temperature.     

Synthesis,crystal structures and spectroscopic studies of calcium(II) succinamate(-1) complexes

The reaction of succinamic acid (H₂sucm) with Ca(NO₃)₂·4H₂O yielded compounds [Ca(Hsucm)(NO₃)(H₂O)]_n (1) and [Ca(Hsucm)₂]_n (2). The succinamate(-1) ligand presents two new ligation modes and coordinates through the two carboxylato and the amide O-atoms, thus bridging three Ca^II ions which assemble into zig-zag 1D chains in 1 and 2D networks in 2. Intermolecular hydrogen bonding interactions in the crystal structures of 1 and 2 result in overall 3D framework structures. Both compounds have been characterized by IR and ¹H NMR spectroscopy, and their thermal decomposition was monitored by TG/DTG and DSC measurements. The structural comparison of 1 and 2 with known lanthanide(III) succinamate(-1) complexes reveals differences in the coordination mode of the ligand and in the coordination number of the metal ions; the biological relevance of these differences is discussed.     

Syntheses,structures and luminescent properties of four copper(I) cyanide coordination polymers based on 2-(n-pyridyl)benzimidazole ligands (n = 2, 3, 4)

Four copper(I) cyanide coordination polymers containing 2-(n-pyridyl)benzimidazole ligands, namely [Cu₂(CN)(2-PyBIm)]_n (1), [Cu₂(CN)₂(3-PyHBIm)]_n (2), {[Cu₃(CN)₃(4-PyHBIm)₄] · 2H₂O}_n (3) and [Cu₅(CN)₃(4-PyBIm)₂]_n (4), have been synthesized and characterized by X-ray crystallography. Complex 1 is a one-dimension coordination polymer in which 2-(2-pyridyl)benzimidazole is deprotonated and adopts a bridging tridentate coordination mode. Complex 2 has ladder-like structure in which 2-(3-pyridyl)benzimidazole does not deprotonate and acts as a bidentate bridge. Complex 3 displays a saddle-shaped helical chain constructed through μ₂-cyanide group and the outstretched neutral 2-(4-pyridyl)benzimidazole monodentate ligand. Complex 4 shows two-dimension layer polymeric structure in which deprotonated 2-(4-pyridyl)benzimidazole acts as a tridentate bridging ligand. The cyanide groups in four complexes all act as bidentate bridging ligands. These complexes are thermal stable and display luminescence in the solid states.     

Solvothermal syntheses and structures of indium(III)-binaphthalenyl dicarboxylate complexes with yellow/blue luminescence

Two novel In(III) complexes, [In(bna)(Hbna)]_n (1) and [In₂(bna)₂(μ₂-OH)₂]_n·4nH₂O (2) (H₂bna=2,2′-dihydroxy-1,1′-binaphthyl-3,3′-dicarboxylate acid), have been reported. Complex 1 adopts a 2D layer structure, where each layer composed from homochiral ligands is chiral while the ligands in two neighboring layers are enantiomer. Complex 2 is constructed by individual -In-O-In- chains, which are further connected by bna²⁻ into a 3D honeycomb framework. As a derivative of H₂bna ligand, dmbna (3) was recrystallized for structurally comparison with 1-2 (dmbna=dimethyl 2,2′-dihydroxy-1,1′-binaphthyl-3,3′-dicarboxylate). X-ray powder diffractions (XRD) and thermogravimetric analyses (TGA) for 1-2 show that they are highly thermally stable in the solid state. Complexes 1 and 2 exhibit the intense yellow luminescence at 573 nm and blue luminescence at 459 nm at room temperature, respectively. And an astonishing blue shift of 105 nm is observed for complex 1 when it is measured at 10 K.     

Three novel lanthanide complexes with imidazole-4,5-dicarboxylate ligand: Hydrothermal syntheses, structural characterization, and properties

Three novel lanthanide complexes, namely, [Ce(Himdc)(H₂imdc)(H₂O)₃]·H₂O (1), {[Dy(Himdc)(Ox)_0.5(H₂O)₂]·H₂O}_n (2), and {[Nd(Himdc)(Ox)_0.5(H₂O)₂]·H₂O}_n (3) (H₃imdc = imidazole-4,5-dicarboxylic acid, Ox = oxalate), have been successfully prepared by the assembly of lanthanide ions and H₃imdc ligand under different synthetic conditions. All of the complexes have been characterized by means of elemental analysis, IR, TG analysis, luminescence spectroscopy as well as single-crystal X-ray diffraction analysis. The 3D supramolecular structure of 1 is constructed from 1D zig-zag chains through the hydrogen bonding interactions. Complex 2 possesses the chair-shaped secondary building units (SBUs) with Dy₆(Himdc)₄(Ox)₂ and meso-helical chains (P + M), resulting in a novel 2D structure based on the linkages of oxalate ligand. Complex 3 also presents 2D layer structure with uninodal 6-connected net topology, but crystallizes in the different space group and owns higher coordination number of the central metal atom than complex 2. The luminescence property of 2 is investigated in the solid state at room temperature.     

Various coordination architectures constructed from N-[(carboxyphenyl)-sulfonyl]glycine: Structural variation via ligand isomerism effects and metal-directed assembly

Using Cu(II), Mn(II) or Co(II) salt and the flexible ligands, N-[(4-carboxyphenyl)-sulfonyl]glycine (H₃L₁) and N-[(3-carboxyphenyl)-sulfonyl]glycine (H₃L₂), a series of new coordination polymers, [Mn(phen)(H₂O)₄][HL₁] (1), [Co₃(L₁)₂(bipy)₃(H₂O)₆]_n·8nH₂O (2), [Cu₄(L₁)₂(OH)₂(bipy)₄]_n·12nH₂O (3), [Na(H₂L₁)(H₂O)]_n (4), [Mn₂(HL₂)₂(dpe)₃(H₂O)₂]_n·ndpe (5), (phen = 1,10-phenanthroline, bipy = 4,4′-bipyridine, dpe = 1,2-di(4-pyridyl)ethylene), varying from 0D to 3D, have been synthesized and structurally characterized. Compound 1 has a [Mn(phen)(H₂O)₄]²⁺ cation and a HL₁²⁻ anion. Compound 2 features a new 1D triple chain, based on octahedral cobalt atoms bridged by bipy molecules and terminally coordinated by two H₃L₁ ligands. Compound 3 has a 2D layered structure, constructed from new alternating chains where H₃L₁, hydroxyl and water molecules simultaneously act as bridging ligands. Compound 4 possesses a bilayer structure in which two adjacent layers are pillared by H₃L₁ ligands into a 2D bilayer network. Compound 5 is a unique 3D coordination polymer in which each Mn center binds two trans-located dpe molecules. The thermal stability as well as magnetic properties of 5 was also studied. This work and our previous work indicate that the positional isomer of the anionic N-[(carboxyphenyl)-sulfonyl]glycine is important in the construction of these network structures, which are also significantly regulated by the metal centers.     

The tunable coordination architectures of a flexible multicarboxylate N-(4-carboxyphenyl)iminodiacetic acid via different metal ions, pH values and auxiliary ligand

{[Pb₃(CPIDA)₂(H₂O)₃]·H₂O}_n1, {[Cd₃(CPIDA)₂(H₂O)₄]·5H₂O}_n2, [Cd(HCPIDA)(bpy)(H₂O)]_n3 (bpy=4,4′-bipyridine) and {[Co₃(CPIDA)₂(bpy)₃(H₂O)₄]·2H₂O}_n4 were synthesized with N-(4-carboxyphenyl) iminodiacetic acid (H₃CPIDA). In 1, the CPIDA³⁻ ligands adopt chelating and bridging modes with Pb(II) to possess a 3D porous framework. In 2D-layer 2, the CPIDA³⁻ ligands display a simple bridging mode with Cd(II). The 2D layers have parallelogram-shaped channels along a axis. With bpy ligands, the HCPIDA²⁻ ligands in 3 show more abundant modes, but 3 still displays a 2D sheet on bc plane for the unidentate bpy molecules. However, in 3D-framework 4, the bpy ligands adopt bridging bidentate at a higher pH value and the CPIDA³⁻ ligands show bis-bidentate modes with Co(II). Additionally, 2D correlation analysis of FTIR was introduced to ascertain the characteristic adsorptions location of the carboxylate groups with different coordination modes in 4 with thermal and magnetic perturbation. Compounds 1, 2 and 4 exhibit the fluorescent emissions at room temperature.     

Synthesis, crystal structures and characterization of four coordination polymers based on 5-amino-2,4,6-triiodoisophthalic acid

One homochiral 1D coordination polymer [Cu(ATIBDC)(2,2′-bipy)]·3H₂O·CH₃OH (1) and three achiral 1D coordination polymers: [Cd(ATIBDC)(2,2′-bipy)(H₂O)]·3H₂O (2), [Cd(ATIBDC)(phen)(H₂O)]·4H₂O (3), and [Mn(ATIBDC)(phen)₂]·5H₂O (4) have been synthesized and characterized (H₂ATIBDC=5-amino-2,4,6-triiodoisophthalic acid, 2,2′-bipy=2,2′-bipyridine, and phen=1,10-phenanthroline). Extended high dimensional network architectures are further constructed with the help of weak secondary interactions, such as hydrogen bonding, aromatic stacking, and halogen bonding (C-I…π and C-I…N/O). Complex 1 crystallizes in the monoclinic system with chiral space group P2(1) and exhibits a right-handed 2₁ helical chain structure. The homochirality of 1 was confirmed by CD spectrum. Interestingly, two new configurations of decameric water cluster are found in 3 and 4. The acyclic tetrameric cluster (H₂O)₃(CH₃OH) in 1 and (H₂O)₄ in 2 array into highly ordered helical infinite chains. Thermal stabilities of all the complexes have been studied. Solid state fluorescent properties of the Cd(II) complexes have been explored.     

Syntheses and characterization of triorganotin complexes: X-ray crystallographic study of triorganotin pyridinedicarboxylates with trinuclear, 1D polymeric chain and 2D network structures

A series of new triorganotin(IV) pyridinedicarboxylates [(C₂H₅)₃NH][(Me₃Sn)₃(2,6-pdc)₂(H₂O)₂] (1), [(C₂H₅)₃NH][(Ph₃Sn)₃(2,6-pdc)₂(H₂O)₂] (2), [(C₂H₅)₃NH]{[(PhCH₂)₃Sn]₃(2,6-pdc)₂(H₂O)₂} (3), [Me₃Sn(3,5-pdc)]_n (4), [Ph₃Sn(3,5-pdc)]_n (5), [(PhCH₂)₃Sn(3,5-pdc)]_n (6), [(Me₃Sn)₂(2,5-pdc)]_n (7), [(Ph₃Sn)₂(2,5-pdc)]_n (8) and {[(PhCH₂)₃Sn]₂(2,5-pdc)}_n (9) were synthesized by the reaction of trimethyltin(IV), triphenyltin(IV) or tribenzyltin(IV) chloride with 2,6(3,5 or 2,5)-H₂pdc (pdc = pyridinedicarboxylate) when triethylamine was added. Complexes 1-9 have been characterized by elemental, IR, ¹H, ¹³C and ¹¹⁹Sn NMR analyses. Among them complexes 1, 5 and 7 have also been characterized by X-ray crystallographic diffraction analyses. Complex 1 has a trinuclear structure and forms a 2D supramolecular structure due to the coordinated water molecules via hydrogen bonds to the pendant O atoms of the carboxyl groups and the N atoms derived of the pyridine ring. Complex 5 forms a 1D polymeric chain by the intermolecular Sn?N (N atom derived of pyridine ring) interactions. Complex 7 has a network structure where 2,5-pyridinedicarboxylate acts as a tetradentate ligand coordinated to trimethyltin(IV) ions.     

Syntheses, structures, and photoluminescence of three-dimensional lanthanide coordination polymers with 2,5-pyridinedicarboxylic acid

Four new open-framework coordination polymers of lanthanide 2,5-pyridinedicarboxylates, with the formulas Pr2(pydc)₃(H₂O)₂ (1), Ln(pydc)(Hpydc) (Ln=Tb (2), Er (3), Eu (5)), and Gd(pydc)(nic)(H₂O) (4) (H₂pydc=2,5-pyridinedicarboxylic acid, Hnic=nicotinic acid), have been hydrothermally synthesized and four of them (except Eu (5)) have been structurally characterized. Complex 1 consists of two types of ligand-binding modes contributing to link the PrO₇N(H₂O) polyhedral chains to three-dimensional (3D) open-framework architecture. Complexes 2 and 3 are isostructural and feature unique 3D cage-like supramolecular frameworks remarkably different from that of 1, owing to the different ligand-bridging pattern. Complex 4, however, has the distinct 3D open-framework architecture due to the presence of unexpected nicotinate ligands, which may be derived from pydc ligands via in-situ decarboxylation under the hydrothermal condition.