Metal Coordination Stoichiometry Controlled Formation of Linear and Hyperbranched Supramolecular Polymers

Controlling the topologies of polymers is a hot topic in polymer chemistry because the physical and/or chemical properties of polymers are determined (at least partially) by their topologies. This study exploits the host–guest interactions between dibenzo‐24‐crown‐8 and secondary ammonium salts and metal coordination interactions between 2,6‐bis(benzimidazolyl)‐pyridine units with metal ions (Zn^II and/or Eu^III) as orthogonal non‐covalent interactions to prepare supramolecular polymers. By changing the ratios of the metal ion additives (Zn(NO₃)₂ and Eu(NO₃)₃) linkers to join the host–guest dimeric complex, the linear supramolecular polymers (100 mol% Zn(NO₃)₂ per ligand) and hyperbranched supramolecular polymers (97 mol% Zn(NO₃)₂ and 3 mol% Eu(NO₃)₃ per ligand) are separately and successfully constructed. This approach not only expands topological control over polymeric systems, but also paves the way for the functionalization of smart and adaptive materials.

     

Use of a cyclo-P4 building block – a way to networks of host–guest assemblies

Despite the proven ability to form supramolecular assemblies via coordination to copper halides, organometallic building blocks based on four-membered cyclo-P₄ ligands find only very rare application in supramolecular chemistry. To date, only three types of supramolecular aggregates were obtained based on the polyphosphorus end-deck complexes Cp^RTa(CO)₂(η⁴-P₄) (1a: Cp^R = Cp′′; 1b: Cp^R = Cp′′′), with none of them, however, possessing a guest-accessible void. To achieve this target, the use of silver salts of the weakly coordinating anion SbF₆⁻ was investigated as to their self-assembly in the absence and in the presence of the template molecule P₃Se₄. The two-component self-assembly of the building block 1a and the coinage-metal salt AgSbF₆ leads to the formation of 1D or 3D coordination polymers. However, when the template-driven self-assembly was attempted in the presence of an aliphatic dinitrile, the unprecedented barrel-like supramolecular host–guest assembly P₃Se₄@[{(Cp′′Ta(CO)₂(η⁴-P₄))Ag}₈]⁸⁺ of 2.49 nm in size was formed. Moreover, cyclo-P₄-based supramolecules are connected in a 2D coordination network by dinitrile linkers. The obtained compounds were characterised by mass-spectrometry, ¹H and ³¹P NMR spectroscopy and X-ray structure analysis.

A one-pot self-assembly template-controlled reaction is reported to result in a 2D coordination network of first host-guest assemblies P₃Se₄@[{(Cp′′Ta(CO)₂(η⁴-P₄))Ag}₈]⁸⁺ of 2.49 nm in size based on an organometallic complex with a cyclo-P₄ end-deck.     

Structure and characterization of organotin bimetallic supramolecular coordination polymers based on copper cyanide building blocks and pyrazine or pyrazine-2-carboxylic acid as new promising anticancer agents

The supramolecular coordination polymers (SCP); _∞³[Cu (CN)₂(Me₃Sn)(pyz)], pyrazine-trimethyltin-bis (cyanide) copper^I SCP 1 , [Cu₂(CN)₃(Ph₃Sn)(pyz)], pyrazine-triphenyltin-tris (cyanide) dicopper^I SCP 3 and [Cu₂(CN)₄(Ph₃Sn)(Pyz2caH)₂], bis-pyrazine-2-carboxylic acid- triphenyltin-tetrakis (cyanide) dicopper^I SCP 4 and the coordination complex (CC), [Cu^II (Pyz2-ca)₂(H₂O)₂]; diaquo-bis-(pyrazine-2-carboxylato) copper^(II) complex: CC 2 , are synthesized by self-assembly method at ambient conditions. Single crystal X-ray structures of SCP 1 and CC 2 indicate the presence of Cu^I and Cu^II which adopt tetrahedral and octahedron geometry, respectively. The structures of SCP 3 and SCP 4 are solved by the density functional theory (DFT) calculations and spectroscopic methods. The Cu centers acquire triagonal plane, linear and tetrahedral geometry, respectively. The CN-R₃Sn-NC spacer and pyrazine or pyrazine-2-carboxylic acid ligands extend the structures to 3D-network. The tested compounds 1–4 are designed and synthesized to examine their effects on viability and proliferation of five human cancer cell lines. Also, they are tested for antioxidant activity using ABTS assay and rate erythrocyte hemolysis.     

Main‐Chain Supramolecular Polymers Based on Orthogonal Benzo‐21‐Crown‐7/Secondary Ammonium Salt and Terpyridine/Metal Ion Recognition Motifs

Orthogonal self‐assembly of multiple components represents an efficient strategy to afford hierarchical and multifunctional assemblies. Here, we demonstrate the orthogonal recognition behaviors between benzo‐21‐crown‐7/secondary ammonium salt and terpyridine/metal ions (Fe²⁺ or Zn²⁺) recognition motifs. Main‐chain supramolecular polymers are subsequently achieved via “one‐pot” mixing of the three monomers together (heteroditopic monomer 1 , homoditopic secondary ammonium salt monomer 2, and Fe(BF₄)₂•6H₂O or Zn(OTf)₂), which are confirmed by ¹H NMR, UV–Vis, DOSY, and viscosity measurements. Moreover, different metal ions (Fe²⁺ or Zn²⁺) exert considerable effects on the size of the resulting supramolecular polymers. Integration of two different types of non‐covalent interactions renders dynamic and responsive properties for the resulting supramolecular polymers, as triggered by a variety of external stimuli such as temperature, potassium cation, as well as stronger chelating ligands. Therefore, the current work is a prerequisite for the future application of such orthogonal assemblies as intelligent supramolecular materials.

     

Host–guest supramolecular polymers constructed of aniline derivatives and three-dimensional coordination polymers [(n-Bu3Sn)2(R3Sn)Fe(CN)6] n,R = n-Bu or Ph

The straightforward self-assembly reaction of R₃Sn⁺ and [Fe(CN)₆]^3? affords three-dimensional (3-D) coordination polymers [(n-Bu₃Sn)₂(R₃Sn)Fe(CN)₆] _n , R = n-Bu(I) or Ph(II). The architecture of these coordination polymers is closely related to zeolite and acts as a host with wide internal cavities or channels capable of encapsulating voluminous organic compounds. Aniline derivatives acting as guest are encapsulated within the cavities of the 3-D-polymeric hosts I and II by tribochemical reaction producing host–guest supramolecular polymers. The structures and physical properties of these hosts and their host–guest systems were investigated by elemental analysis, X-ray powder diffraction, IR, UV-vis, EPR, and magnetic measurements. The morphology of these systems was examined by scanning electron microscopy (SEM). The interesting feature of these host–guest supramolecular polymers is the enhanced electrical conductivities over those of the 3-D-coordination polymeric hosts upon encapsulation of conductive polymers within their cavities.     

Orthogonal chain length control in calix[5]arene-based AB-type supramolecular polymers

New AB-type supramolecular polymers have been prepared by acid-promoted self-assembly of an aminododecyloxy-calix[5]arene monomer precursor. The number-average degree of polymerization has been found to be dependent on the concentration of the salt monomer and on the nature of the counterion (i.e., chloride, picrate or hexafluorophosphate).Chain-length regulation experiments have been carried out, employing orthogonal chain stoppers capable of selectively interacting with a given moiety of the AB-type monomer/polymer. Competitive calix[5]arene ‘caps’ and n-butylammonium ion ‘plugs’ have been used to control the extent of self-assembly of the polymer, in turn interacting with the ammoniumdodecyloxy or with the cavity end-groups of the supramolecular calixarene assembly. These experiments, conveniently carried out at a 10 mM concentration, can be easily followed by ¹H NMR spectroscopy.     

Supramolecular Paradigm for Capture and Co-Precipitation of Gold(III) Coordination Complexes

A new supramolecular paradigm is presented for reliable capture and co-precipitation of haloauric acids (HAuX₄) from organic solvents or water. Two classes of acyclic organic compounds act as complementary receptors (tectons) by forming two sets of directional non-covalent interactions, (a) hydrogen bonding between amide (or amidinium) NH residues and the electronegative X ligands on the AuX₄⁻, and (b) electrostatic stacking of the electron deficient Au center against the face of an aromatic surface. X-ray diffraction analysis of four co-crystal structures reveals the additional common feature of proton bridged carbonyls as a new and predictable supramolecular design element that creates one-dimensional polymers linked by very short hydrogen bonds (CO⋅⋅⋅OC distance <2.5 Å). Two other co-crystal structures show that the amidinium-π⋅⋅⋅XAu interaction will reliably engage AuX₄⁻ with high directionality. These acyclic compounds are very attractive as co-precipitation agents within new “green” gold recovery processes. They also have high potential as tectons for controlled self-assembly or co-crystal engineering of haloaurate composites. More generally, the supramolecular paradigm will facilitate the design of next-generation receptors or tectons with high affinity for precious metal square planar coordination complexes for use in advanced materials, nanotechnology, or medicine.     

Supramolecular Fullerene Polymers and Networks Directed by Molecular Recognition between Calix[5]arene and C60

A biscalix[5]arene–C₆₀ supramolecular structure was utilized for the development of supramolecular fullerene polymers. Di‐ and tritopic hosts were developed to generate the linear and network supramolecular polymers through the complexation of a dumbbell‐shaped fullerene. The molecular association between the hosts and the fullerene were carefully studied by using ¹H NMR, UV/Vis absorption, and fluorescence spectroscopy. The formation of the supramolecular fullerene polymers and networks was confirmed by diffusion‐ordered ¹H NMR spectroscopy (DOSY) and solution viscometry. Upon concentrating the mixtures of di‐ or tritopic hosts and dumbbell‐shaped fullerene in the range of 1.0–10 mmol L^?1, the diffusion coefficients of the complexes decreased, and the solution viscosities increased, suggesting that large polymeric assemblies were formed in solution. Scanning electron microscopy (SEM) was used to image the supramolecular fullerene polymers and networks. Atomic force microscopy (AFM) provided insight into the morphology of the supramolecular polymers. A mixture of the homoditopic host and the fullerene resulted in fibers with a height of (1.4±0.1) nm and a width of (5.0±0.8) nm. Interdigitation of the alkyl side chains provided secondary interchain interactions that facilitated supramolecular organization. The homotritopic host generated the supramolecular networks with the dumbbell‐shaped fullerene. Honeycomb sheet‐like structures with many voids were found. The growth of the supramolecular polymers is evidently governed by the shape, dimension, and directionality of the monomers.     

Recent Progress in Azobenzene-Based Supramolecular Materials and Applications

Azobenzene-containing small molecules and polymers are functional photoswitchable molecules to form supramolecular nanomaterials for various applications. Recently, supramolecular nanomaterials have received enormous attention in material science because of their simple bottom-up synthesis approach, understandable mechanisms and structural features, and batch-to-batch reproducibility. Azobenzene is a light-responsive functional moiety in the molecular design of small molecules and polymers and is used to switch the photophysical properties of supramolecular nanomaterials. Herein, we review the latest literature on supramolecular nano- and micro-materials formed from azobenzene-containing small molecules and polymers through the combinatorial effect of weak molecular interactions. Different classes including complex coacervates, host-guest systems, co-assembled, and self-assembled supramolecular materials, where azobenzene is an essential moiety in small molecules, and photophysical properties are discussed. Afterward, azobenzene-containing polymers-based supramolecular photoresponsive materials formed through the host-guest approach, polymerization-induced self-assembly, and post-polymerization assembly techniques are highlighted. In addition to this, the applications of photoswitchable supramolecular materials in pH sensing, and CO₂ capture are presented. In the end, the conclusion and future perspective of azobenzene-based supramolecular materials for molecular assembly design, and applications are given.     

Syntheses,Crystal Structures,and Photoluminescence of Zinc(II) and Cobalt(II) Coordination Polymers Based on Semiflexible 1,4‐Bis(4‐phenoxy)benzenedicarboxylate

Hydrothermal reactions of Co(NO₃)₂ · 6H₂O and Zn(NO₃)₂ · 6H₂O with 1,4‐bis(4‐phenoxy)benzenedicarboxylic acid (H₂bcpb) resulted in the formation of the coordination polymers [Zn(bcpb)(Py)]_n ( 1 ), and [Co(bcpb)(Py)₂]_n ( 2 ), respectively. Their structures were studied by single‐crystal and powder X‐ray diffraction methods and further characterized by IR spectroscopy, elemental analyses, and thermogravimetric analyses (TGA). Single X‐ray diffraction analyses revealed that complex 1 has a 1D loop chain. Each repeated unit contains two carboxylate ligands and two SBUs (secondary building units), whereas complex 2 has a 2D 4‐connected sql sheet with point symbol (4⁴.6²). The complexes are further expanded to 3D supramolecular structures through non‐covalent bonding interactions. Besides, photoluminescent property of complex 1 was also investigated in the solid state at room temperature.     

P4VP and oligo(phenylenevinylene)‐perylenebisimide mixed donor‐acceptor supramolecular comb polymer complexes with improved charge carrier mobility

Random donor‐acceptor (D‐A) supramolecular comb polymers were formed when hydroxyl functionalized donor and acceptor small molecules based on Oligo(phenylenevinylene) (named OPVCN‐OH ) and Perylenebisimide (named UPBI‐PDP ), respectively, were complexed with Poly(4‐vinyl pyridine) (P4VP). A series of random D‐A supramolecular comb polymers were formed by varying the ratios of UPBI‐PDP and OPVCN‐OH with P4VP. A 100% P4VP‐donor polymer complex [ P4VP(OPV_1.00 )] and a 100% P4VP‐acceptor polymer complex [ P4VP(UPBI_1.00 )] were also synthesized and characterized. Complex formation was confirmed by FT‐IR and ¹H NMR spectroscopy. Solid state structural studies carried out using small angle X‐ray scattering and wide angle X‐ray diffraction experiments revealed altered packing of the D and A molecules in the complexes. Transmission electron microscopy images showed lamellar structures in the < 10 nm scale for the P4VP(OPV_1.00 ), P4VP(UPBI_1.00 ), and mixed P4VP (D‐A) complexes. The effect of the nanoscopic D‐A self‐assembly on the bulk mobility of the materials was probed using SCLC measurements. The mixed D‐A random complexes exhibited ambipolar charge transport characteristics with higher values for the average bulk hole mobility estimate. P4VP(OPV_0.25 + UPBI_0.75) exhibited an average hole mobility in the order of 10^?2cm² V^?1 s^?1 and electron mobility 10^?5cm² V^?1 s^?1. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2403–2412     

Synthesis, structural characterization and selectively catalytic properties of metal-organic frameworks with nano-sized channels: A modular design strategy

Modular design method for designing and synthesizing microporous metal-organic frameworks (MOFs) with selective catalytical activity was described. MOFs with both nano-sized channels and potential catalytic activities could be obtained through self-assembly of a framework unit and a catalyst unit. By selecting hexaaquo metal complexes and the ligand BTC (BTC=1,3,5-benzenetricarboxylate) as framework-building blocks and using the metal complex [M(phen)₂(H₂O)₂]²⁺ (phen=1,10-phenanthroline) as a catalyst unit, a series of supramolecular MOFs 1-7 with three-dimensional nano-sized channels, i.e. [M¹(H₂O)₆]·[M²(phen)₂(H₂O)₂]₂·2(BTC)·xH₂O (M¹, M²Co(II), Ni(II), Cu(II), Zn(II), or Mn(II), phen=1,10-phenanthroline, BTC=1,3,5-benzenetricarboxylate, x=22−24), were synthesized through self-assembly, and their structures were characterized by IR, elemental analysis, and single-crystal X-ray diffraction. These supramolecular microporous MOFs showed significant size and shape selectivity in the catalyzed oxidation of phenols, which is due to catalytic reactions taking place in the channels of the framework. Design strategy, synthesis, and self-assembly mechanism for the construction of these porous MOFs were discussed.     

Synthesis,structure and characterization of two copper(II) supramolecular coordination polymers based on a multifunctional ligand 2‐amino‐4‐sulfobenzoic acid

Copper(II) coordination polymers have attracted considerable interest due to their catalytic, adsorption, luminescence and magnetic properties. The reactions of copper(II) with 2‐amino‐4‐sulfobenzoic acid (H₂asba) in the presence/absence of the auxiliary chelating ligand 1,10‐phenanthroline (phen) under ambient conditions yielded two supramolecular coordination polymers, namely (3‐amino‐4‐carboxybenzene‐1‐sulfonato‐κO¹)bis(1,10‐phenanthroline‐κ²N,N′)copper(II) 3‐amino‐4‐carboxybenzene‐1‐sulfonate monohydrate, [Cu(C₇H₆N₂O₅S)(C₁₂H₈N₂)₂](C₇H₆N₂O₅S)·H₂O, (1), and catena‐poly[[diaquacopper(II)]‐μ‐3‐amino‐4‐carboxylatobenzene‐1‐sulfonato‐κ²O⁴:O^4′], [Cu(C₇H₆N₂O₅S)(H₂O)₂]_n, (2). The products were characterized by FT–IR spectroscopy, thermogravimetric analysis (TGA), solid‐state UV–Vis spectroscopy and single‐crystal X‐ray diffraction analysis, as well as by variable‐temperature powder X‐ray diffraction analysis (VT‐PXRD). Intermolecular π–π stacking interactions in (1) link the mononuclear copper(II) cation units into a supramolecular polymeric chain, which is further extended into a supramolecular double chain through interchain hydrogen bonds. Supramolecular double chains are then extended into a two‐dimensional supramolecular double layer through hydrogen bonds between the lattice Hasba⁻ anions, H₂O molecules and double chains. Left‐ and right‐handed 2₁ helices formed by the Hasba⁻ anions are arranged alternately within the two‐dimensional supramolecular double layers. Complex (2) exhibits a polymeric chain which is further extended into a three‐dimensional supramolecular network through interchain hydrogen bonds. Complex (1) shows a reversible dehydration–rehydration behaviour, while complex (2) shows an irreversible dehydration–rehydration behaviour.     

Synthesis and Single Crystal Structure Characterization of Dinuclear and Polymeric Mixed-ligand Coordination Compounds of Zinc(II) and Cadmium(II) with the Bridging Ligand 1,2-Bis(pyridin-4-ylmethylene)hydrazine

Three d¹⁰-transition-metal coordination compounds [Cd(tfpb)₂(4-bpmh)]_n ( 1 ), [Cd(9-aca)(NO₃)(OHCH₃)(4-bpmh)]_n ( 2 ) and [Zn₂(dpp)₄(4-bpmh)] ( 3 ) with the bridging ligand 4-bpmh were synthesized [4-bpmh = 1,2-bis(pyridin-4-ylmethylene)hydrazine, tfpb = 4,4,4-trifluoro-1-phenylbutane-1,3-dionate, 9-aca = anthracene-9-carboxylate, dpp = 1,3-diphenylpropane-1,3-dionate]. Compounds 1 – 3 were characterized by FT-IR spectroscopy, elemental analysis, and structurally authenticated by X-ray crystallography. Compounds 1 – 3 are constructed by an O,O'-donor ligand including chelating β-diketonates (tfpb, dpp) in 1 and 3 and a carboxylate ligand (9-aca) in 2 in combination with a linear neutral bidentate and bridging N-ligand (4-bpmh). The assembly and action of the bridging 4-bpmh ligand leads to one-dimensional coordination polymers in 1 , 2 and to a dinuclear coordination complex in 3 . The structures and the solid-state supramolecular interactions for studying the crystal packing fashions of 1 – 3 were analyzed. The supramolecular interactions including hydrogen bonding, C–H ··· π, π ··· π, and C–F ··· π in 1 , 2 , and 3 were founded.     

Supramolecular polymers fabricated by orthogonal self-assembly based on multiple hydrogen bonding and macrocyclic host–guest interactions

Supramolecular polymers constructed by orthogonal self-assembly based on multiple hydrogen bonding and macrocyclic host-guest interactions have received increasing attention due to their elegant structures,outstanding properties,and potential applications.Hydrogen bonding endows these supramolecular polymers with good adaptability and reversibility,while macrocyclic host-guest interactions give them good selectivity and versatile stimuli-responsiveness.Therefore,functional supramolecular polymers fabricated by these two highly specific,noninterfering interactions in an orthogonal way have shown wide applications in the fields of molecular machines,electronics,soft materials,etc.In this review,we discuss the recent advances of functional supramolecular polymers fabricated by orthogonal self-assembly based on multiple hydroge n bonding and host-guest interactions.In particular,we focus on crown ether-and pillar[n]arene-based supramolecular polymers due to their compatibility with multiple hydrogen bonds in organic solution.The fabrication strategies,interesting properties,and potential applications of these advanced supramolecular materials are mainly concerned.     

Three porous coordination polymers of Co2+ and dpdo ligands with channels hosting polyanion chains

Three porous coordination polymers, {[Co(dpdo)₄(H₂O)₂][H(H₂O)₆](PMo₁₂O₄₀)} _n (1), {[Co(dpdo)₄(H₂O)₂][H₃O(CH₃OH)₄](PMo₁₂O₄₀)} _n (2) and {[Co(dpdo)₄(H₂O)₂][K(CH₃OH)₄](PMo₁₂O₄₀)} _n (3) (where dpdo is 4,4′-bipyridine-N,N′-dioxide), with special channels for the chain-like assembly of polymeric Keggin-type anions have been synthesized through self-assembly of Co²⁺ and dpdo ligands in acetonitrile/water or methanol/water solutions and characterized by single crystal X-ray diffraction. Based on layers constructed by [Co(dpdo)₄(H₂O)₂]^{2 +} and different bridging units for charge compensation between layers, the three compounds exhibit similar noninterwoven networks with large channels occupied by the poly-Keggin-anion chains. Thermogravimetric analyses suggest that the three supramolecular networks have different thermal stabilities based on different cationic bridging units.     

Two Cadmium(II) Coordination Polymers based on Pamoic Acid and Different Polydentate N-donor Ligands: Syntheses,Crystal Structures,and Fluorescence Properties

Two new fluorescent coordination polymers based on pamoic acid and different polydentate N-donor ligands, namely {[Cd(PA)(TPTZ)(H₂O)](DMF)₂}_n ( 1 ) and [Cd(PA)(BIB)]_n ( 2 ) [H₂PA = pamoic acid, TPTZ = 2,4,6-tri(2-pyridyl)-1,3,5-triazine, BIB = 1,4-bis(1-imidazolyl)benzene], were synthesized and characterized. Complex 1 showed a 1D zigzag chain structure with intramolecular hydrogen bonds. The 2D supramolecular structure in 1 was formed through π–π stacking interactions and intermolecular hydrogen bonds. Complex 2 displayed a 2D network structure. Intramolecular hydrogen bonds and π–π stacking interactions were observed in 2 . By studying the fluorescence sensing performance of two coordination polymers, complex 1 exhibited high selectivity for tracking Al³⁺ ion and complex 2 could discriminately detect inorganic or aliphatic amines with high selectivity.     

Self-healing and shape memory functions exhibited by supramolecular liquid-crystalline networks formed by combination of hydrogen bonding interactions and coordination bonding

We here report a new approach to develop self-healing shape memory supramolecular liquid-crystalline (LC) networks through self-assembly of molecular building blocks via combination of hydrogen bonding and coordination bonding. We have designed and synthesized supramolecular LC polymers and networks based on the complexation of a forklike mesogenic ligand with Ag⁺ ions and carboxylic acids. Unidirectionally aligned fibers and free-standing films forming layered LC nanostructures have been obtained for the supramolecular LC networks. We have found that hybrid supramolecular LC networks formed through metal–ligand interactions and hydrogen bonding exhibit both self-healing properties and shape memory functions, while hydrogen-bonded LC networks only show self-healing properties. The combination of hydrogen bonds and metal–ligand interactions allows the tuning of intermolecular interactions and self-assembled structures, leading to the formation of the dynamic supramolecular LC materials. The new material design presented here has potential for the development of smart LC materials and functional LC membranes with tunable responsiveness.

New supramolecular hybrid liquid-crystalline networks exhibiting self-healing and shape memory properties are developed by self-assembly of small components through hydrogen bonding interactions and coordination bonding.     

Supramolecular microrods can be prepared by mixing aqueous Ru(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>Cl<Subscript>3</Subscript> and K<Subscript>3</Subscript>Fe(CN)<Subscript>6</Subscript> solutions at room temperature

This paper describes the ionic self-assembly method to fabricate supramolecular one-dimensional microrods in solution. Such microrods were formed in a one-step process through the mixing aqueous Ru(NH₃)₆Cl₃ and K₃Fe(CN)₃ solutions at room temperature. Chemical composition of the resulting structures, which are composed of from Fe(CN)₆⁴⁻ and Ru(NH₃)₆³⁺, was determined by energy-dispersed spectroscopy. The data show that the formation of microrods depends on the molar ratio and concentration of the reactants.     

Structures and properties of Sm(III) coordination polymers based on 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarboxylate

Two novel 1D and 3D Sm(III) coordination polymers involving the 2-pyridin-4-yl-4,5-imidazoledicarboxylic acid (H₃PIDC) ligand have been characterized by infrared spectroscopy, elemental analysis and single-crystal X-ray diffraction. The coordination polymers were synthesized under hydrothermal conditions. Coordination polymer 1 gave a 1D zigzag chain, then forming 3D supramolecular structure through π?π stacking interactions and hydrogen bonds. Coordination polymer 2, in which oxalate was introduced as the second ligand gave a 3D framework with a 3,3-connected (4.8⁵)(4.8²) topology structure. But the luminescence of the coordination polymers has significant quenching.