Formation Of 1D Coordination Polymer Research Articles

Solvent-dependent formation of 1D coordination polymers based on polynuclear copper(II)-carboxylate fragments and 4-(pyridine-3-yl)methyleneamino-1,2,4-triazole linkers

The solvent used for the synthesis and crystallization was shown to affect the composition and structure of compounds formed in the reaction of copper(II) trimethylacetate with a Schiff base, 4-(pyridin-3-yl)methyleneamino-1,2,4-triazole (L). The reaction of [Cu2(piv)4(Hpiv)2] (Hpiv – trimethylacetic acid) in MeCN was found to give the crystals of 1D coordination polymer {[Cu2(piv)4(L)]·MeCN}n (1), the structure of which contains binuclear {Cu2(piv)4} units linked by the bridging organic ligand L. A similar reaction in MeOH or EtOH gave 1D coordination polymers {[Cu6(OH)2(piv)10(L)2(ROH)2]∙4ROH}n (2: R = Me, 3: R = Et) whose structure is composed of alternating binuclear {Cu2(piv)4} and tetranuclear {Cu4(OH)2(piv)6(L)2(ROH)2} units bound by N-donor ligand L. Storage of the mother liquor obtained after the isolation of the crystals of 3 leads to the crystallization of chained polymer [Cu(piv)2L]n (4). The structures of new complexes 1–4 were determined by single crystal X-ray diffraction. According to magnetochemical measurements for 1 and 3, antiferromagnetic exchange interactions are observed in these compounds between CuII ions (S = ½) in binuclear {Cu2(piv)4} units (J = −190.5 and −215 cm−1, respectively), as well as dominate in tetranuclear {Cu4(OH)2(piv)6(L)2(EtOH)2} units of 3 (J1 = −202 cm−1, J2 = –23 cm−1, J3 = 18 cm−1).

Binuclear Triphenylantimony(V) Catecholates through N-Donor Linkers: Structural Features and Redox Properties.

A series of binuclear triphenylantimony(V) bis-catecholato complexes 1–11 of the type (Cat)Ph3Sb-linker-SbPh3(Cat) was prepared by a reaction of the corresponding mononuclear catecholates (Cat)SbPh3 with a neutral bidentate donor linker ligands pyrazine (Pyr), 4,4′-dipyridyl (Bipy), bis-(pyridine-4-yl)-disulfide (PySSPy), and diazobicyclo[2,2,2]octane (DABCO) in a dry toluene: Cat = 3,6-di-tert-butyl-catecholate (3,6-DBCat), linker = Pyr (1); PySSPy (2); Bipy (3); DABCO (4); Cat = 3,5-di-tert-butyl-catecholate (3,5-DBCat), linker = Bipy (5); DABCO (9); Cat = 4,5-(piperazine-1,4-diyl)-3,6-di-tert-butylcatecholate (pip-3,6-DBCat), linker = Bipy (6); DABCO (10); Cat = 4,5-dichloro-3,6-di-tert-butylcatecholate (4,5-Cl2-3,6-DBCat), linker = Bipy (7); DABCO (11); and Cat = 4,5-dimethoxy-3,6-di-tert-butylcatecholate (4,5-(MeO)2-3,6-DBCat), linker = Bipy (8). The same reaction of (4,5-Cl2-3,6-DBCat)SbPh3 with DABCO in an open atmosphere results in a formation of 1D coordination polymer {[(4,5-Cl2-3,6-DBCat)SbPh3·H2O]·DABCO}n (12). Bis-catecholate complex Ph3Sb(Cat-Spiro-Cat)SbPh3 reacts with Bipy as 1:1 yielding a rare macrocyclic tetranuclear compound {Ph3Sb(Cat-Spiro-Cat)SbPh3∙(Bipy)}2 (13). The molecular structures of 1, 3, 4, 5, 8, 10, 12, and 13 in crystal state were established by single-crystal X-ray analysis. Complexes demonstrate different types of relative spatial positions of mononuclear moieties. The nature of chemical bonds, charges distribution, and the energy of Sb...N interaction were investigated in the example of complex 5. The electrochemical behavior of the complexes depends on the coordinated N-donor ligand. The coordination of pyrazine, Bipy, and PySSPy at the antimony atom changes their mechanism of electrooxidation: instead of two successive redox stages Cat/SQ and SQ/Cat, one multielectron stage was observed. The coordination of the DABCO ligand is accompanied by a significant shift in the oxidation potentials of the catecholate ligand to the cathodic region (by 0.4 V), compared to the initial complex.

Effect of the flexible chain length of a dimetal subunit on the formation of 1D coordination polymers to molecular rectangles.

Utilizing the angular and rigid furan dicarboxylate (fdc2-) ion, a new series of four (1-4) metal-organic coordination networks (MOCNs) is synthesized in good yields through a one-pot self-assembly reaction in methanol under ambient conditions to demonstrate the effect of Cu2 dimetal subunits, connected by flexible polypyridyl bis(tridentate) ancillary ligands, tpxn, where x refers to the number of methylene groups connecting the alkyl nitrogen atoms in the ancillary ligands and is equal to 2, 4, 6, and 7. The solid-state molecular structures of 1-4 are determined by single-crystal X-ray diffraction. A change in the dimensionality of the resultant MOCN is observed from a 1D coordination polymer (CP) for 1, 2, and 3 to a molecular rectangle for 4. Furthermore, each unit of 4 contains one NaClO4. Using electrospray ionization (ESI) mass spectrometry, their structural integrity in solution and their purity of existence as a single product are confirmed. Further characterization of 1-4 by FTIR and UV-vis (in solution and solid-state) spectroscopy, and FESEM and TEM is also reported. The presence of unsaturated metal centers in 1-4 provided an opportunity to compare their Lewis acid catalytic activities for the Knoevenagel condensation reaction of malononitrile with various aldehydes.

Formation of 1D coordination polymers by reaction of a tetrazine ligand and PbX2 (X: Br, I) salts: Spectral, structural and theoretical studies

Two lead(II) 1D-coordination polymers, [Pb3(μ-BPTZ)2(μ4-Br)(μ3-Br)(μ-Br)3Br]n (1) (BPTZ = 3,6-di(pyridin-2-yl)-1,2,4,5-tetrazine) and [Pb(HPMPHz)(μ-I)2]n (2) (HPMPHz = zwitterionic form of N-(pyridin-2-ylmethylene)picolinohydrazonic acid, HPMPH) were prepared and identified by elemental analysis, FT-IR spectroscopy and single-crystal X-ray diffraction. The crystal structure of 1, is the first example for coordination of a tetrazine ligand to the lead(II) ion. The 1D chain in 1 is expanding by BPTZ and bromide bridges. Three different coordination environments were found for lead atoms: PbN4(μ4-Br)(μ3-Br)(μ-Br)2 with cube geometry; PbN2(μ4-Br)(μ3-Br)(μ2-Br)Br and PbN2(μ4-Br)(μ3-Br)2(μ2-Br)2 with capped octahedral geometries. Ligands around these lead(II) ions are arranged in hemidirected mode. X-ray analysis of 2 revealed a ring opening hydrolysis reaction that converts BPTZ ligand to the HPMPHz. This structure is the first example for a PbN2OI4 coordination environment which is extended by iodide bridges and contains hemidirected pentagonal bipyramidal coordinated lead(II) ions. Also 2 is the first example containing zwitterionic form of HPMPH. In the crystal network of the complexes, in addition to hydrogen bonds there are π–π stacking interactions between pyridine rings. Optical properties of the compound 1 were investigated by UV–Vis diffuse reflectance and emission spectroscopy methods in solid state. According to the DFT calculated electronic band structures, the compounds are indirect band gap semiconductors. Linear optical properties of the compounds (including the dielectric function, absorption coefficient, reflectivity, refractive index, optical conductivity and energy loss function) are also investigated by DFT method.

Crystal formation of 1D coordination polymers based on chiral, achiral and racemic 1,2-cyclohexane scaffolds

Enantiomerically pure ligands (1a and 1b) and meso1c based on trans-1,2-cyclohexanediol and cis-1,2-cyclohexanediol, respectively, were used for the formation of zigzag 1D coordination polymers, when combined with bent HgCl2.

Coordination Polymers Formed by the Reactions between Zn(II), Co(II), and Ni(II) Cimantrenates and γ,γ'-Dipyridyl in Methanol

Reactions between methanol adducts of Zn(II), Co(II), and Ni(II) cimantrenates and γ,γ′-dipyridyl in methanol have been found to result in the formation of 1D coordination polymers, whose structure is governed, according to X-ray diffraction data, by the nature of the transition metal.

1D Chains of Diruthenium Tetracarbonyl Sawhorse Complexes

The syntheses of five 1D coordination polymers containing the sawhorse‐type unit [Ru2(µ‐OAc)2(CO)4] linked by various bridging N,N‐donor ligands are reported. Various π‐conjugated linkers, such as trans‐[1,2‐bis(N‐methyl)imidazol‐2‐yl]ethylene (trans‐bie), pyrazine (pyz), 4,4′‐bipyridine (4,4′‐bipy) and 1,2‐bis(4‐pyridyl)ethylene (bpe) as well as the aliphatic linker 1,4‐diazabicyclo[2.2.2]octane (DABCO), were applied in the syntheses. The formation of 1D coordination polymers was proven by crystal structure determinations of two of the polymeric materials. The geometries and electronic structures of all polymers were analysed further by CASSCF/CASPT2 and DFT calculations based on monomeric model compounds. Finally, first attempts regarding deposition of the 1D chain, the sawhorse fragment and/or the ligands on a highly ordered pyrolytic graphite surface, analysed by STM measurements, are also reported.

Synthesis, structural analyses and antimicrobial activity of the water soluble 1D coordination polymer [Ag(3-aminopyridine)]ClO4

The synthesis, characterization and molecular structure aspects of the [Ag(3-aminopyridine)]ClO4 coordination polymer have been presented. Single crystal X-ray diffraction (SC-XRD) analysis showed that the asymmetric unit consists of two Ag, one 3-aminopyridine (3APy) and one ionic perchlorate anion. The 3-aminpyridine (3APy) acts as a bridged ligand connecting the Ag-atoms via the amine and pyridine ring N-atoms leading to the formation of 1D coordination polymer. The perchlorate anion connects the 1D chains via a complicated set of NH⋯O and CH⋯O hydrogen bonding interactions. Strong FTIR spectral bands at 1143.1, 1116.7 and 1085.6 cm−1 and a weak band at 932.9 cm−1 revealed the ionic character of the complex. Single point DFT calculations combined with atoms in molecules (AIM) and natural bond orbital (NBO) analyses indicated stronger AgN(py) than AgN(NH2) interaction. The former has more covalent character according to the AIM topological parameters. The Ag⋯O interactions are weak and are mainly affected by dispersion interactions. Of the six DFT methods used for geometry optimizations, the TPSSTPSS then PBEPBE are the most powerful DFT methods to predict the AgN distances. Effect of methods on the frontier molecular orbitals energies and shapes are also presented. Preliminary antimicrobial studies showed that the [Ag(3APy)]ClO4 complex has more activity against all the studied microorganisms than the free 3APy.

Coordination polymers and metal-organic frameworks: materials by design.

The field of coordination polymers and metal–organic frameworks (MOFs) has evolved over a period of approximately 25 years to a stage where it is one of the most widely investigated areas of materials chemistry. The field has impacted many areas of science including commercial applications from

Complexes of non-lacunary Keggin- and Dawson-type polyoxometalates with Pb(ii): formation of 1D coordination polymers with different bonding modes

A new coordination polymer based on Keggin-type [SiW12O40]4− and Pb2+ ions, {Pb2(μ2-DMF)2(DMF)8(SiW12O40)} (1a), was prepared by a reaction between H4[SiW12O40] and Pb(NO3)2 in N,N-dimethylformamide (DMF). Varying the crystallization conditions, a complex with a slightly different coordination mode of the {Pb2} unit and solvate composition, {Pb2(μ2-DMF)2(DMF)8(SiW12O40)}·DMF (1b), can be obtained. The complex containing Well–Dawson polyoxoanions, {(Pb(μ2-DMF)3(DMF)6)(Pb(DMF)5)(P2W18O62)}·0.5DMF·1.3H2O (2), was prepared by a similar strategy.

Chalcogenated (S)-(−)-nicotine derivatives as chiral linkers for 1D coordination polymers

Reactions of zinc(II) chloride with (S)-(−)-nicotine (Nic), cotinine, thionicotine and selenonicotine in 1:1molar ratio yielded new metal complexes, which were characterized by elemental analysis, infrared, 13C and 1H NMR spectral methods. Single crystal X-ray diffraction studies of ZnCl2 complexes with thionicotine and selenonicotine revealed that the two complexes form isostructural crystals build of 1D coordination polymers (CP) and that coordination to metal centers alters the conformation of the parent organic ligand from syn to anti. Quantum chemical calculations indicate that in the isolated state the anti conformation of the uncoordinated chalcogen nicotine lactams is slightly more preferred energetically and it does not undergo substantial changes upon coordination to the metal center. The preference for the syn conformation in crystals of thio- and selenolactams of nicotine might be ascribed to their involvement in columnar stacking interactions, which do not operate in the isolated state and are also absent in crystals of their adducts with ZnCl2. This study has provided useful information regarding functionalization of (S)-(−)-nicotine molecule as a mixed-donor-atom ligand to enforce formation of 1D coordination polymers.

Bis(methyl)(thia/selena)salen Ag(i) complexes: counter-ion induced structural diversity

The complexation behaviour of bis(methyl)(thia/selena)salen ligands towards Ag(I) ions in the presence of PF6−, ClO4− and NO3− ions, and the self-assembling of the resultant complexes were explored. Changes in counter anion and coordinating sites (S/Se) led to a structural diversity of complexes as determined using single-crystal X-ray diffraction. The crystallographic study of silver complexes 1 and 2 derived from La and Lb, respectively, in the presence of PF6− ions, revealed the formation of 1D coordination polymers. In the cationic polymer 1, the metal center adopts a distorted square pyramidal geometry where the N2S2 donor set of a ligand molecule forms a basal plane while the S atom from another ligand molecule forms an axial bond, which is responsible for the establishment of the coordination polymer. Unlike complex 1 (with a S-ligating site), complex 2 (with a Se-ligating site) is a polymer with a bimetallic unit where the two metal centers (Ag1 and Ag2) differ in their coordination spheres. In the analogous complexes 3 and 4 involving ClO4− as the counter anion, the polymeric frameworks resemble that of 1 but the existence of π–π interactions between the aromatic rings of the two distinct polymeric chains construct a 2D-sheet, while no direct interaction was observed between the polymeric chains in 1 and 2. The presence of NO3− ions yielded the bimetallic metallacycle 5 possessing a center of inversion. The ligand molecules are coordinated in a tridentate mode and the tetrahedral environment around the silver ion was established with the coordination of a nitrate ion.

Crystal Engineering with 2-Aminopurine Containing a Carboxylic Acid Pendant

This article reports synthesis, design, and luminescent properties of a series of structurally interesting coordination frameworks prepared from a modified purine ligand, 3-(2-amino-9H-purin-9-yl) propanoic acid (L). Corresponding transition metal complexes reported in this study were unambiguously characterized by X-ray crystallography to reveal an array of diverse crystallographic signatures reflecting crystal design around varying coordination geometries of a central metal ion. While silver complex 1 [C16H18Ag2N10O5] affords formation of coordination framework with embedded dimeric, tetrameric, and pentameric metallacycles, corresponding copper complexation results in a discrete dimer 2 [C32H46Cl2Cu2N20O14]. Changing the counteranion from strongly coordinating chloride ion to weakly coordinating perchlorate anion resulted in the formation of a 1D coordination polymer 3 [C18H26Cl2CuN10O14]. Cobalt complexes 4 [C16H32CoN10O12] and 5 [C16H30CoN12O16] yielded 2D grid-type assembly and a discrete dimer, respectively. Change in pH offered an interesting effect on the structural outcome of cadmium complexes: acidic and neutral conditions lead to the formation of 1D coordination polymer 6 [C8H12CdCl2N6O6] and 7 [C16H24Cd2N12O14], while basic conditions yielded an unusual porous metal organic framework 8 [C9H15CdN5O5.5].

Fluorescence Enhancement of a Porphyrin–Viologen Dyad by Pseudorotaxane Formation with Cucurbit[7]uril

AbstractDicationic viologen species are known to form strong supramolecular complexes with cucurbit[7]uril, as well as participate in electron‐transfer processes with donor systems. We describe the use of cucurbit[7]uril to modulate the electron transfer between a hybrid porphyrin (donor) and a viologen (acceptor) dyad. The X‐ray crystal structure of these hybrids reveals the formation of 1D coordination polymers held together through zinc coordination in the solid state.

A supramolecular dual-host based ion-pair induced formation of 1D coordination polymer

An N-bridged tripodal urea receptor (L1) in combination with 18-crown-6-ether (LC) has been structurally authenticated to self-assemble into an integrated 1D coordination polymer in the presence of potassium carbonate (K2CO3). The tripodal receptor (L1) encapsulates a carbonate anion within a dimeric capsular assembly. A carbonyl group and a nitro group from each tripodal unit of the dimeric assembly are coordinated to each crown ether bound potassium ion, generating a 1D coordination polymer. Thus, an anion-pair induced 1D integrated polymeric assembly is formed based on two hosts in combination.

Thermally reversible single-crystal to single-crystal transformation of mononuclear to dinuclear Zn(ii) complexes by [2+2] cycloaddition reaction

Two Zn(II) complexes of trans-4-styrylpyridine ligands undergo [2+2] cycloaddition reaction forming Zn(II) complex dimers in a single-crystal to single-crystal (SCSC) manner which were thermally reversible. The dimers are presumed to be the stable intermediates in the formation of 1D coordination polymers upon prolonged exposure to UV light.

Combination of covalent and hydrogen bonding in the formation of 3D uranyl-carboxylate networks

Four compounds containing uranyl cation [UO 2] 2+ have been synthesized hydrothermally by reacting uranyl acetate and uranyl nitrate with various N/O donor ligands. The structure of all compounds was elucidated by single crystal X-ray diffraction study. Compound [(UO 2)(6-methylnicotinato) 3](H 3O)·4H 2O ( 1) is a discrete complex (0D), that gives rise in the crystal to hydrophilic channels, while [(UO 2)(OH)( μ 2-3-pyridylpropionato)] n ( 2) and [(UO 2)(H 2O)( μ 3-4,4′-oxybis(benzoato)] n ( 3) show the formation of 1D coordination polymers. Moreover, oxalate anions, formed in situ by using 5-methylisophthalic or 2,3-pyrazinedicarboxylic acid as reactant ligands, gave rise to a 2D coordinating network [(UO 2) 2( μ 2-oxalate)( μ 2-OH) 2(H 2O) 2] n · nH 2O ( 4). All the complexes expanded their dimensionality to 3D through hydrogen bonds.

Binding of zinc(II) macrocycles toward carboxylate ligands

Three new zinc(II) complexes, Zn(L1)(NO3)2(1), {[Zn(L1)(fumarate)]·2H2O}n(2) and {[Zn(L2)(fumarate)]·DMF}n(3) (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo [14,4,01.18,07.12]docosane) have been synthesized and characterized by analytical, spectroscopic, thermal and X-ray diffraction methods. The structure of the discrete neutral complex (1) shows that the central zinc(II) ion is coordinated axially by two nitrate ligands. In the structures (2) and (3), the carboxylate groups of the bridging fumarate ligands are coordinated to zinc(II) macrocycles, resulting in the formation of 1D coordination polymers. Apart from the fairly strong Zn–O bonds in (2) and (3), it is observed that the hydrogen bonds between the pre-organized N–H groups of the macrocycle and axial ligands appear to be important for the design and development of metal complexes having a strong Zn–O bond.

New copper(II) 1D polymer containing dimethyl(phenylsulfonyl)amidophosphate: Synthesis, crystal structure and magnetic properties

The reaction of sodium dimethyl(phenylsulfonyl)amidophosphate Na L (H L = C 6H 5SO 2NHP(O)(OCH 3) 2) with Cu(NO 3) 2 · 6H 2O and o-bpe (1,2-bis(pyridine-2-yl)ethane) in appropriate ratios, afford the formation of 1D coordination polymer [Cu( L) 2 · o-bpe] n in good yield. The crystal structures of H L ( 1) and [Cu( L) 2 · o-bpe] n ( 2) are reported. In the crystal package the molecules of 1 are linked by intermolecular hydrogen bonds formed by the phosphoryl oxygen atoms which serve as acceptors and nitrogen atoms of amide groups as donors. The crystal structure of 2 indicates the presence of unsaturated Cu( L) 2 unit bridged by o- bpe ligand in the one-dimensional polymeric chain. The Cu(II) atoms have distorted 4 + 2 octahedral CuO 4N 2 environment formed by the oxygen atoms belonging to the sulfonyl and phosphoryl groups of two deprotonated chelate ligands and nitrogen atoms of the bridging o-bpe ligands. The magnetic study of 2 has revealed the presence of a weak intrachain antiferromagnetic exchange interaction between copper ions.

Self-assembly of silver(i) and bis-bidentate N,N-donor ligands: from a tetranuclear complex to coordination polymers

The supramolecular self-assembly structures of one tetranuclear silver(i) complex and three silver(i) coordination polymers derived from bis-bidentate imino-pyridine ligands and their reduced N-methyl derivatives are discussed. Six new ligands were synthesised, and the X-ray structural analysis of L(1), L(2) and L(5) with silver(i) ions indicated the formation of 1D coordination polymers, namely {[AgL(1)]BF(4)}(n) (1), {[AgL(2)]ClO(4)}(n) (2), and {[AgL(5)]ClO(4).H(2)O}(n) (5), whereas ligand L(4) led to a tetranuclear complex {[AgL(4)]ClO(4)}(4) (4). L(1) is the Schiff-base derived from the condensation of alpha,alpha'-diamino-m-xylene and pyridine-2-carboxaldehyde and L(4) that resulting from the reaction of 2-(4-aminophenyl)ethylamine with 6-methyl-pyridine-2-carboxaldehyde, while L(2) and L(5) are the reduced N-methyl derivatives. The structural determination shows achiral syndiotactic polymers for 1 and chiral isotactic for 2 and 5. The 1D coordination chains of 1 are stabilised by intramolecular pi-pi stacking interactions between the phenyl ring of a spacer with the pyridine of a symmetry related adjacent ligand, while the crystal packing of 5 show inter-chain pi-pi interactions. Compound 4 comprises discrete tetranuclear [AgL(4)](4)(4+) complex cations and the rhomboid disposition of the metal ions leads to a globular arrangement of the silver(i) complex. The results provide an insight about the effect of ligand spacer length and flexibility in stabilising the metallo-supramolecular architecture.