Assembly Of Coordination Polymers Research Articles

Supramolecular Assembly of One-Dimensional Coordination Polymers for Efficient Separation of Xenon and Krypton.

Efficient separation and purification of xenon (Xe) from krypton (Kr) represent an industrially crucial but challenging process. While the adsorption-based separation of these atomic gases represents an energy-efficient process, achieving highly selective adsorbents remains a difficult task. Here, we demonstrate a supramolecular assembly of coordination polymers, termed as M(II)-dhbq (M = Mg, Mn, Co, and Zn; dhbq = 2,5-dihydroxy-1,4-benzoquinone), with high-density open metal sites (5.3 nm-3) and optimal pore size (5.5 Å), which are able to selectively capture Xe among other chemically inert gases including Kr, Ar, N2, and O2. Among M(II)-dhbq materials, Mn-dhbq exhibits the highest Xe uptake capacity of 3.1 mmol/g and a Xe/Kr selectivity of 11.2 at 298 K and 1.0 bar, outperforming many state-of-the-art adsorbents reported so far. Remarkably, the adsorption selectivity of Mn-dhbq for Xe/O2, Xe/N2, and Xe/Ar at ambient conditions reaches as high as 70.0, 139.3, and 64.0, respectively. Direct breakthrough experiments further confirm that all M(II)-dhbq materials can efficiently discriminate Xe atoms from other inert gases. It is revealed from the density functional theory calculations that the strong affinity between Xe and the coordination polymer is mainly attributed to the polarization by open metal sites.

Designing of Interdigitated Coordination Polymer for Fluorogenic Sensing of Pd(II) in Water with Reversible Nonphase Mechanochromism

AbstractIn the present study, a novel interdigitated coordination polymer (CP) [Zn(cit)(4‐nvp)]n (1) is synthesized using citraconic acid (H2cit) and 4‐(1‐naphthylvinyl)pyridine (4‐nvp) mixed ligands. The efficient dipolar interactions between CP and polar solvents cause the observed redshift in emission spectra and rationalize the positive solvatochromism effect with increased Stokes shift (Δδ) from 5643 to 8547 cm−1 on going from less‐polar to more‐polar solvents. Supramolecular assembly of CP acts as a selective optical sensor toward Pd(II) even in the presence of other relevant contending metal ions in water. Inspired from the solution‐phase sensor activity, the CP is further employed for an on‐site and ecologically green contact mode detection of Pd(II) from water upon readily fabricating cost‐effective and portable thin film via simply drop‐casting aqueous suspension of material (1 mm) on filter paper. Interestingly, the compound exhibits the rare mechanochromic behavior upon external pressure. Hence, the synthesized CP reveals sensing activity in diverse way; in one hand, it demonstrates solvatochromism and, in other hand, it unveils mechanochromism accompanied by the detection of Pd(II) in aqueous medium.

Aquaporin-Inspired CPs/AAO Nanochannels for the Effective Detection of HCHO: Importance of a Hydrophilic/Hydrophobic Janus Device for High-Performance Sensing.

Probe reactivity has long been considered to play a key role in artificial nanochannel sensors, but systematic studies of membrane wettability on detection performance are currently lacking. Inspired by biological aquaporins, we developed an effective strategy to regulate the hydrophilic/hydrophobic balance by the controllable in situ assembly of coordination polymers (CPs) using BDC-NH2 on anodic aluminum oxide (AAO) nanochannels to promote HCHO detection. We found that the hydrophobic/hydrophilic balance in CP/AAO heterosomes plays significant roles in the effective detection of HCHO. The hydrophobic AAO barrier layer is necessary to support the confinement effect, while the hydrophilic CP surface is favorable for HCHO to access the channels and then condense with the responsive amine to generate a new imine. The optimized CP/AAO Janus device shows excellent performance in the quantitative analysis of HCHO over a wide range from 100 pM to 1 mM by monitoring the rectified ionic current.

Isomeric 4,2′:6′,4″- and 3,2′:6′,3″-Terpyridines with Isomeric 4′-Trifluoromethylphenyl Substituents: Effects on the Assembly of Coordination Polymers with [Cu(hfacac)2] (Hhfacac = Hexafluoropentane-2,4-dione)

The isomers 4′-(4-(trifluoromethyl)phenyl)-4,2′:6′,4″-terpyridine (1), 4′-(3-(trifluoromethyl)phenyl)-4,2′:6′,4″-terpyridine (2), 4′-(4-(trifluoromethyl)phenyl)-3,2′:6′,3″-terpyridine (3), and 4′-(3-(trifluoromethyl)phenyl)-3,2′:6′,3″-terpyridine (4) have been prepared and characterized. The single crystal structures of 1 and 2 were determined. The 1D-polymers [Cu2(hfacac)4(1)2]n·2nC6H4Cl2 (Hhfacac = 1,1,1,5,5,5-hexafluoropentane-2,4-dione), [Cu(hfacac)2(2)]n·2nC6H5Me, [Cu2(hfacac)4(3)2]n·nC6H4Cl2, [Cu2(hfacac)4(3)2]n·nC6H5Cl, and [Cu(hfacac)2(4)]n·nC6H5Cl have been formed by reactions of 1, 2, 3 and 4 with [Cu(hfacac)2]·H2O under conditions of crystal growth by layering and four of these coordination polymers have been formed on a preparative scale. [Cu2(hfacac)4(1)2]n·2nC6H4Cl2 and [Cu(hfacac)2(2)]n·2nC6H5Me are zig-zag chains and the different substitution position of the CF3 group in 1 and 2 does not affect this motif. Packing of the polymer chains is governed mainly by C–F...F–C contacts, and there are no inter-polymer π-stacking interactions. The conformation of the 3,2′:6′,3″-tpy unit in [Cu2(hfacac)4(3)2]n·nC6H4Cl2 and [Cu(hfacac)2(4)]n·nC6H5Cl differs, leading to different structural motifs in the 1D-polymer backbones. In [Cu(hfacac)2(4)]n·nC6H5Cl, the peripheral 3-CF3C6H4 unit is accommodated in a pocket between two {Cu(hfacac)2} units and engages in four C–Hphenyl...F–Chfacac contacts which lock the phenylpyridine unit in a near planar conformation. In [Cu2(hfacac)4(3)2]n·nC6H4Cl2 and [Cu(hfacac)2(4)]n·nC6H5Cl, π-stacking interactions between 4′-trifluoromethylphenyl-3,2′:6′,3″-tpy domains are key packing interactions, and this contrasts with the packing of polymers incorporating 1 and 2. We use powder X-ray diffraction to demonstrate that the assemblies of the coordination polymers are reproducible, and that a switch from a 4,2′:6′,4″- to 3,2′:6′,3″-tpy metal-binding unit is accompanied by a change from dominant C–F...F–C and C–F...H–C contacts to π-stacking of arene domains between ligands 3 or 4.

Emergence of Metallic Conductivity in Ordered One-Dimensional Coordination Polymer Thin Films upon Reductive Doping.

The prospect of introducing tunable electric conductivity in metal-organic coordination polymers is of high interest for nanoelectronic applications. As the electronic properties of these materials are strongly dependent on their microstructure, the assembly of coordination polymers into thin films with well-controlled growth direction and thickness is crucial for practical devices. Here, we report the deposition of one-dimensional (1D) coordination polymer thin films of N,N'-dimethyl dithiooxamidato-copper by atomic/molecular layer deposition. High out-of-plane ordering is observed in the resulting thin films suggesting the formation of a well-ordered secondary structure by the parallel alignment of the 1D polymer chains. We show that the electrical conductivity of the thin films is highly dependent on their oxidation state. The as-deposited films are nearly insulating with an electrical conductivity below 10-10 S cm-1 with semiconductor-like temperature dependency. Partial reduction with H2 at elevated temperature leads to an increase in the electrical conductivity by 8 orders of magnitude. In the high-conductance state, metallic behavior is observed over the temperature range of 2-300 K. Density functional theory calculations indicate that the metallic behavior originates from the formation of a half-filled energy band intersecting the Fermi level with the conduction pathway formed by the Cu-S-Cu interaction between neighboring polymer chains.

Synthesis, structure and photoluminescence properties of a three-dimensional cadmium(II) (4,5)-connected coordination network.

The assembly of coordination polymers from metal ions and organic moieties is currently attracting considerable attention in crystal engineering due to their intriguing architectures and potential applications as functional materials. A new coordination polymer, namely poly[[μ2-trans-1,2-bis(pyridin-3-yl)ethylene-κ2N:N']bis(μ4-4,4'-oxydibenzoato-κ6O:O,O':O'':O'',O''')dicadmium(II)], [Cd2(C14H8O5)2(C12H10N2)]n or [Cd2(4,4'-OBB)2(3,3'-BPE)]n, has been synthesized by the the self-assembly of Cd(NO3)2·4H2O, 4,4'-oxydibenzoic acid (4,4'-H2OBB) and trans-1,2-bis(pyridin-3-yl)ethene (3,3'-BPE) under hydrothermal conditions. The title compound was structurally characterized by IR spectroscopy, elemental analysis and single-crystal X-ray diffraction analysis. Each CdII centre is coordinated by six carboxylate O atoms from four different 4,4'-OBB2- ligands and by one pyridyl N atom form a 3,3'-BPE ligand. Adjacent crystallographically equivalent CdII ions are bridged by 4,4'-OBB2- ligands, affording a two-dimensional [Cd(4,4'-OBB)]n net extending in the ac plane. Neighbouring [Cd(4,4'-OBB)]n nets are interlinked by 3,3'-BPE along the b axis to form a three-dimensional (3D) [Cd2(4,4'-OBB)2(3,3'-BPE)]n coordination network. In the network, each CdII centre is linked by four different 4,4'-OBB2- ligands and one 3,3'-BPE ligand. Meanwhile, each 4,4'-OBB2- ligand connects four separate CdII ions. Therefore, if the 4,4'-OBB2- ligands and CdII ions are considered as 4- and 5-connecting nodes, the structure of the title compound can be simplified as a 3D (4,5)-connected binodal framework with the rare (4462)(4466) TCS topology (Pearson, 1985; Blake et al., 2011). The thermal stability and photoluminescence properties of the title compound have also been investigated.

Chiral expression from molecular to macroscopic level via pH modulation in terbium coordination polymers

Chiral expression from the molecular to macroscopic level is common in biological systems, but is difficult to realise for coordination polymers (CPs). The assembly of homochiral CPs in both crystalline and helical forms can provide a bridge for understanding the relationship between the molecular and macroscopic scales of chirality. Herein, we report homochiral helices of [Tb(R- or S-pempH)3]∙2H2O (R- or S-1) (pempH2 = (1-phenylethylamino)methylphosphonic acid) and their crystalline counterparts (R- or S-3), which are formed at different pH of the reaction mixtures under hydrothermal conditions. By combining the experiments and molecular simulations, we propose that the formation of helices of R-1 or S-1 occurs via a hierarchical self-assembly route, which involves twisted packing due to the geometric incompatibility of the different types of chains. The observed chiral transcription from molecules to morphologies is significant for understanding bio-related self-assembly processes on the nano- to macro-scale.

Tetratopic bis(4,2′:6′,4′′-terpyridine) and bis(3,2′:6′,3′′-terpyridine) Ligands as 4-Connecting Nodes in 2D-Coordination Networks and 3D-Frameworks

Ditopic, 4,2′:6′,4′′-terpyridine (4,2′:6′,4′′-tpy) and 3,2′:6′,3′′-terpyridine (3,2′:6′,3′′-tpy) present a divergent N,N′-donor set (the central N atom typically being non-coordinated) and are ideal building blocks for the assembly of coordination polymers and networks. The step from ditopic to tetratopic ligands which contain two interconnected 4,2′:6′,4′′-tpy or 3,2′:6′,3′′-tpy metal-binding domains renders the ligand capable of acting as a 4-connecting node and is a successful route to increasing the dimensionality of the assembly. In this short overview, we illustrate the recent development of the use of bis(4,2′:6′,4′′-tpy) and bis(3,2′:6′,3′′-tpy) ligands and compare strategies using either ditopic or tetratopic ligands.

Alkyl group-directed assembly of coordination polymers based on bis-(4-imidazol-1-yl-phenyl)-amine and their photocatalytic properties

Four new coordination polymers have been solvothermally synthesized to explore their diverse networks and photocatalytic properties.

Assembly of 1,3,5-tris(2-alkylthiol-pyrimidin-4-yl)benzene) (alkyl = Me, n-Pr) with copper(I) iodide: effect of alkyl side chain

Two π-conjugated organic building blocks, TMPB and TPPB (TMPB = 1,3,5-tris(2-methylthiol-pyrimidin-4-yl)benzene; TPPB = 1,3,5-tris(2-propylthiol-pyrimidin-4-yl)benzene), have been prepared which only differ in the length of linear side chain attached to sulfur. Structural comparison between complexes of TMPB and TPPB reveals that the side chain has a great effect in modulating both the molecular structure and the molecular alignment. Reactions of TMPB and TPPB with CuI under the same conditions show that the side chain can exert impact on the assembly of coordination polymer. Assembly reaction with CuI is sensitive to the change in length of side chain, that is the shorter the side chain, the faster the reaction. Reaction of TPPB with CuI gives a 1-D chain structure of [Cu4I4(TPPB)2]n (1) based on two distinctive Cu4I4 clusters, whilst only microcrystalline powder or precipitate can be obtained for TMPB. The side chain can, thus, tune the assembly of coordination polymer in terms of the assembly structure as well as its packing manner.

Construction of Cu(ii), Zn(ii) and Cd(ii) metal–organic frameworks of bis(1,2,4-triazol-4-yl)ethane and benzenetricarboxylate: syntheses, structures and photocatalytic properties

Three coordination polymers {[Cu4(OH)2(btre)(1,2,3-btc)2(H2O)2]·2H2O}n (1), {[Zn4(OH)2(btre)(1,2,3-btc)2(H2O)4]·4H2O}n (2) and {[Cd3(btre)(1,2,3-btc)2(H2O)3]·3H2O}n (3) were synthesized by the hydrothermal method using 1,2-bis(1,2,4-triazol-4-yl)ethane (btre), 1,2,3-benzenetricarboxylate (1,2,3-btc) and metal ions (Cu(II), Zn(II), and Cd(II)). 1 shows a (3,8)-connected 3D metal–organic framework based on the tetranuclear copper(II) cluster [Cu4(μ3-OH)2] with the point symbol of (4·52)3(44·55·612·73·83·9). 2 exhibits a (3,8)-connected 3D metal–organic framework based on the tetranuclear zinc(II) cluster [Zn4(μ3-OH)2] with the point symbol of (42·6)3(46·618·83·10). In 3, each [Cd3(1,2,3-btc)2(H2O)]n chain connects four adjacent identical [Cd3(1,2,3-btc)2(H2O)]n chains through the btre bridges in four different directions, leading to an unusual 3D network. 3 shows a 4-connected 66dia topological net based on the [Cd3(H2O)(COO)4] trimer Cd(II) clusters. The diverse structures demonstrate that the central metal ions play the key role in the assembly of coordination polymers. 1 and 2 show good photocatalytic activity for the degradation of methyl orange. The luminescence of 2 and 3 was investigated.

Supramolecular Assembly of Organophosphonate Diesters Using Paddle-Wheel Complexes: First Examples in Porphyrin Series

The reactions of dicopper tetrapivalate complex Cu2(μ-OOC-t-Bu)4(NCMe)2 (1) with triphenylphosphine oxide and diethyl phosphite allow paddle-wheel (PW) copper(II) complexes with phosphorus-containing axial ligands (2, 3) to be obtained. When meso-bis(diethoxyphosphoryl)porphyrins 4M were employed in this ligand exchange reaction, a series of one-dimensional (1D) homo- and heterometallic coordination polymers 5M composed of PW subunits and organophosphonate diesters were prepared and characterized by means of single crystal X-ray analysis. Planar porphyrinate 4Pd and nonplanar metalloporphyrinates 4Cu and 4Ni proved to be appropriate molecular structural blocks for assembly of coordination polymers. The structural parameters of the tetrapyrrolic macrocycles incorporated into the polymer chain are determined by the nature of the metal center of the porphyrin moiety. While the geometry of palladium(II) and nickel(II) porphyrinates 4Pd and 4Ni does not change significantly in the polymer chain, saddle-shaped Cu(II) porphyrinate 4Cu exhibits a nearly planar core configuration, being coordinated to the copper centers of PW fragments by two peripheral phosphoryl groups in the polymer chain. The geometry of the tetrapyrrolic core is a key parameter influencing the structural properties of the polymeric materials. For 5Pd and for isostructural 5Cu, all metal centers of the polymeric chain are aligned. The planar macrocycles of adjacent chains are parallel and are shifted one to another in such a way that the angle between the Pd···P and Pd···Pd directions is 40.4°, and the distance between the nearest palladium(II) atoms of neighboring chains is 11.668 Å. There is no free volume in these crystals. In the crystals of 5Ni, formed by nonplanar porphyrinates, only copper atoms of the PW pivalate moiety are located in one plane, and zigzag chains are formed so that two adjacent tetrapyrrolic macrocycles are located in alternating positions with respect to this plane, the nickel atoms being displaced from this plane by 1.548 Å. This arrangement naturally leads to the formation of regular pores. The resulting channels have an effective cross-section of about 10 × 12 Å and represent ca. 18% of the volume of the crystal. The exchange reaction between the free-base porphyrin 4H2 and an excess of copper(II) pivalate complex 1 is accompanied by the metalation of the porphyrin core affording the polymer 5Cu. Moreover, self-assembly of metalloporphyrinate 4Zn is observed under studied experimental conditions, which interferes with the formation of the target mixed coordination polymers.

New terpyridine-(β-diketonate)-copper(II) complex. Structure and magnetism

Over the last decade the design and synthesis of metal-organic compounds with fascinating structural properties and potential applications as functional materials has been a major challenge in various fields of research.1Strategies for preparing these compounds are based on the careful selection of the constituent building blocks. 4'-(substituted)-4,2':6',4''-terpyridine ligands are considered versatile building blocks for the assembly of coordination polymers and networks with useful solid-state properties, such as magnetism, luminescence, redox activity, etc.2The divergent arrangements of N-donor atoms and the attachment of aryl substituents into the 4'-position of 4,2':6',4''-terpyridine allow to bridge two or more metal centers, giving rise to molecular assemblies of 1, 2 or 3 dimensions.3Our line of interest is the obtainment of compounds with emergent magnetic properties. Herein we present a copper complex surveying the new 4'-(quinolin-4-yl)-4,2':6',4''-terpyridine ligand (L), and formulated as [Cu(C5H1F6O2)2(C25H16N4·CHCl3)]n which was produced from the reaction of two equivalents of L with Cu(hfac)2, (hfac=hexafluoroacetylacetonate). The copper ion in trans-{CuN2(hfac)2} has an octahedral environment. The nitrogen atoms of the terminal pyridine rings coordinate to the paramagnetic centres, while the central ring remains uncoordinated. The linkage of the resulting polyhedra gives raise to an undulating 1D polymeric structure. Within these chains there are two main non-covalent interactions: π-stacking between the quinoline substituents and the pyridine rings and CH···F interactions due to CF3group of the hfac ligand. There are also weak CH···N, CH···π and π-π intermolecular interactions linking the L and CHCl3groups, which give stability to the crystal structure. Finally, we performed magnetic measurements, in order to determine the magnetic behaviour of our system. Acknowledgments: FONDECYT 1130433 project, CIPA of University of Concepción, LIA-MIF 836

Metal-directed assembly of coordination polymers with the versatile ligand 2-(1H-benzotriazol-1-yl) acetic acid: from discrete structures to two-dimensional networks

Eight new metal coordination complexes, namely, [Co(BTA)2(H2O)4]·6H2O (1), [Ni(BTA)2(H2O)4]·6H2O (2), [Cu2(HBTA)4(BTA)2]·2H2O (3), [Ag(BTA)(H2O)]n (4), [Zn(BTA)2(H2O)]n (5), [Cd(BTA)2(H2O)]n (6), [Cu2(μ3-OH)(BTA)3]n (7), and [Mn(BTA)2(H2O)2]n (8) [HBTA = 2-(1H-benzotriazol-1-yl)acetic acid], were obtained under hydrothermal conditions, by reacting the different metal salts with HBTA. The ligand HBTA was characterized by melting point (m.p.), elemental analysis (EA), infrared spectroscopy (IR), 1H NMR, and X-ray single-crystal diffraction. Complexes 1–8 were structurally characterized by X-ray single-crystal diffraction, EA, IR, PXRD, and thermogravimetry analysis (TGA). These complexes all display low-dimensional features displaying various zero-dimensional (0D), one-dimensional (1D), and two-dimensional (2D) coordination motifs. Complexes 1 and 2 are isostructural and mononuclear; they show unique decamer water clusters with bis-boat conformations, which further extend to a 1D metal–water chain. Through intermolecular hydrogen bonds, these 1D metal–water chains extend to 3D supramolecular networks. Complex 3 shows a bi-nuclear structure. Complex 4 displays a 1D tape structure. There exist weak interactions between Ag⋯Ag. Complexes 5 and 6 form a 1D linear chain bridged by BTA anions. Complex 7 exhibits a 2D layer containing tetranuclear butterfly [Cu4(CO2)4(μ3-OH)] secondary building units (SBUs). Complex 8 possesses a 2D layer and further stacks via hydrogen bonding interactions to generate a three-dimensional supramolecular architecture. These results suggest that both the coordination preferences of the metal ions and the versatile nature of this flexible ligand play a critical role in the final structures. The luminescent spectra show strong emission intensities in complexes 3, 4, 5, and 6. Complexes 3, 5 and 6 display blue photoluminescence. However, complex 4 exhibits green fluorescence. Variable-temperature magnetic susceptibility measurements reveal the existence of antiferromagnetic interactions in both 7 and 8. Additionally, the ferroelectric and second-harmonic generation (SHG) properties of 5 are discussed in detail.

Molecular recognition between 4′-(4-biphenylyl)-4,2′:6′,4″-terpyridine domains in the assembly of d9 and d10 metal ion-containing one-dimensional coordination polymers

Assembly of [{Zn2(μ-OAc)4(1)}n] from reaction of zinc(II) acetate and 4′-(4-biphenylyl)-4,2′:6′,4″-terpyridine (1) using 1:1, 2:1 and 1:2 ratios of Zn(II): 1 is independent of the conditions tested. Free ligand 1 is a rare example of a compound that crystallizes with five independent molecules in the unit cell (Z′=5). Single crystal X-ray diffraction confirms that [{Zn2(μ-OAc)4(1)}n] is a one-dimensional coordination polymer in which 1 bridges {Zn2(μ-OAc)4} nodes. Each polymer chain has a zigzag configuration and chains associate through face-to-face π stacking of pairs of biphenyl domains and pairs of tpy units. The solid state structure of [{Zn2(μ-OAc)4(1)}n] is compared to those of related compounds. Moving from zinc(II) to copper(II) has little effect on the assembly of a coordination polymer with 1, and [{Cu2(μ-OAc)4(1)}n] is isostructural with [{Zn2(μ-OAc)4(1)}n]. With cadmium(II) acetate, a ladder-like polymer chain forms which contains {Cd2(μ,κ3-O,O′:O′-OAc)2(κ2-O,O′-OAc)2} nodes. The electronic absorption and emission properties of 1, [{Zn2(μ-OAc)4(1)}n], [{Cu2(μ-OAc)4(1)}n] and [{Cd2(μ,κ3-O,O′:O′-OAc)2(κ2-O,O′-OAc)2(1)2}n] are discussed. Binding zinc(II) or cadmium(II) red-shifts the ligand-based solid state emission, while the latter is quenched by coordination to copper(II); solution electronic spectroscopic data are consistent with dissembly of the polymer chain.

Time-resolved monitoring of dynamic self-assembly of Au(i)-thiolate coordination polymers

Research interest in dynamic assemblies of coordination polymers (CPs) has been rising in recent years for the similarity with life systems in their self-adaptable morphologies and properties. However, monitoring of the assembly process and elucidating the nature for the morphological transformation are very challenging. Here, UV-Vis spectroscopy has been explored as a time-resolved method for monitoring the self-assembly of Au(I)–thiolate CPs in situ. Both step-wise and synergetic effects of the weak interactions in Au(I)–3-mercaptopropionic acid (MPA) CPs, such as H-bonding, coordination bonding, Au(I)–Au(I) interactions and static interactions have been found from the spectral fingerprints, which elucidated the driving forces for the unique morphological transformations from strings to lamellar structures. This work represents a breakthrough in that dynamic self-assembly behaviours can be explained by molecular interactions from molecular level evidences. Based on the spectral fingerprint–structure relationship the reversible and dynamic assembly of Au(I)–MPA CPs can be easily probed.

Hydroquinone-assisted assembly of coordination polymers from lanthanides and cucurbit[5]uril

Coordination polymers have been assembled from a series of eight different lanthanide ions (Ln3+) and cucurbit[5]uril (Q[5]) in the presence of hydroquinone (Hyq) as an organic structure inducer. X-ray diffraction analysis has revealed three distinct configurations of the coordination polymers formed with increasing atomic number of the lanthanide. The coordination of light lanthanide cations to Q[5] leads to the formation of linear one-dimensional coordination polymers; the coordination of intermediate lanthanide cations such as Eu(III) or Gd(III) leads to the formation of Q[5] pairs in which the two Q[5] molecules are connected by the Eu(III) or Gd(III) ions; and the coordination of heavy lanthanide cations to Q[5] leads to the formation of homochiral one-dimensional helical coordination polymers.

Halogen Bonding in the Assembly of Coordination Polymers Based on 5-Iodo-Isophthalic Acid

A series of seven divalent coordination polymers based on 5-iodo-isophthalic acid (5-iipa) and ancillary nitrogen ligands (phen = 1,10-phenanthroline, bpe = 1,2-bis(4-pyridyl)ethene, p-bix = 1,4-bis(imidazol-1-ylmethyl)-benzene, m-bix = 1,3-bis(imidazol-1-ylmethyl)-benzene), namely, [Zn2(5-iipa)2(phen)2(H2O)]n (1), [Zn(5-iipa)(bpe)1.5]n (2), [Cd2(5-iipa)2(phen)2]n (3), [Mn2(5-iipa)2(phen)2]n (4), [Mn4(5-iipa)4(bpe)4·5H2O]n (5), [Co(5-iipa)(p-bix)]n (6), and [Co(5-iipa)(m-bix)]n (7), have been synthesized. The structure of compound 1 exhibits a double zigzag metal–organic chain, and such chains are further united together to generate a three-dimensional (3D) supramolecular structure through interchain I···π interactions. Compound 2 features interesting 3-fold parallel interpenetrated two-dimensional (2D) → 3D network motifs which are stabilized by interlayer I···π, π···π, and C–H···π interactions. In isomorphous compounds 3 and 4, the 5-iipa2– ligand acts as a μ3-bridge to connect metal atoms to form a 2D metal–organic layer, and such layers are united together to yield a 3D supramolecular structure through interlayer I···π and C–H···π interactions. In the structures of 5 and 7, the rare 2-fold interpenetrating 3D supramolecular architectures based on I···I interactions or O···I halogen bonding are found, respectively. In compound 6, 3-fold interpenetrated 2D → 3D network motifs based on covalent bonding are expanded to a rare 3D supramolecular structure based on O···I halogen bonding. The above results demonstrate a useful guideline in the crystal engineering of supramolecular architectures in coordination network assembly under the influence of halogen bonding as well as related I···I and I···π interactions. Their thermal analysis, X-ray diffraction, UV–vis absorption spectra, and photoluminescent properties have been investigated as well.

Controlling interpenetration in CuCN coordination polymers by size of the pendant substituents of terpyridine ligands

To systematically investigate the effect of the pendant groups of ligands on the assembly of coordination polymers (e.g, controlling interpenetration), four terpyridine ligands with bulky pendant groups, namely, 4′-(4-tolyl)-4,2′:6′,4′′-terpyridine (L1), 4′-(4-ethylphenyl)-4,2′:6′,4′′-terpyridine (L2), 4′-(4-isopropylphenyl)-4,2′:6′,4′′-terpyridine (L3), and 4′-biphenyl-4,2′:6′,4′′-terpyridine (L4) have been synthesized for comparative purposes. The reactions of CuCN and L1–L4 under the same solvothermal conditions provided four CuCN coordination polymers: [(CuCN)2L1]n (1), [(CuCN)2L2]n (2), [(CuCN)2L3]n (3), and {[(CuCN)3L41.5]·H2O}n) (4), respectively. Single-crystal X-ray analyses reveal that compounds 1–3 are isostructural with the same topological 4-fold interpenetrated 3D CuCN networks, and compound 4 is a non-interpenetrated CuCN network. This success demonstrates that the interpenetration is suppressed by the alteration of the size of the pendant groups of terpyridine ligands.

Ligand geometry-driven formation of different coordination polymers from Zn(NO3)2, 1,4-bpeb and phenylenediacetic acids

The hydrothermal reactions of Zn(NO3)2·6H2O with 1,4-bis[2-(4-pyridyl)ethenyl]benzene (1,4-bpeb), NaOH, and 1,4-phenylenediacetic acid (1,4-H2PDA), 1,3-phenylenediacetic acid (1,3-H2PDA) or 1,2-phenylenediacetic acid (1,2-H2PDA) afforded three coordination polymers {[Zn(1,4-PDA)(1,4-bpeb)]·2H2O}n (1), [Zn(1,3-PDA)(1,4-bpeb)]n (2) and [Zn4(μ-OH)2(1,2-PDA)3(1,4-bpeb)2]n (3), respectively. All these compounds were characterized by elemental analysis, IR, powder X-ray diffraction, and single-crystal X-ray diffraction. 1 exhibits a five-fold interpenetrating 3D diamondoid framework constructed by linking Zn atoms with trans-1,4-PDA and trans-trans-trans-1,4-bpeb ligands. 2 has a 2D (4,4) network formed by connecting dinuclear [Zn2(1,3-PDA)2] (1,3-PDA serving as a trans conformation) units with trans-cis-trans-1,4-bpeb ligands. 3 could be considered as a 2D 5-connected network derived from linking tetranuclear [Zn4(μ-OH)2(1,2-PDA)3] (1,2-PDA acting as cis and trans conformations) units via trans-cis-trans-1,4-bpeb bridges. The results provided some insight into the ligand geometry-driven assembly of coordination polymers. Thermal stability and photoluminescent properties of 1–3 were also investigated.