Exploration of semiconducting properties of Zn(ii)- and Cd(ii)-based coordination polymers with dicarboxylate of a chair-type backbone

This study highlights the comparison of electrical properties and device applications of d10 metal ion based coordination polymers.

Bringing a New Flexible Mercaptoacetic Acid Linker to the Design of Coordination Polymers

Two new 3D coordination polymers (CPs), formulated as [Zn(p-XBT)]_n (1H) and [Cd(p-XBT)]_n (2H), were assembled from a virtually unexplored p-xylylene-bis(2-mercaptoacetic) acid linker (p-XBTA) and characterized by infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), thermal analysis methods (TG-DSC, TG-FTIR), single-crystal X-ray diffraction, and topological analysis. Two different synthetic strategies were explored, namely the precipitation (P) and hydrothermal (H) methods, resulting in a Zn(II) derivative [Zn(p-XBT)·H₂O]_n (1P) and its dehydrated analogue [Zn(p-XBT)]_n (1H), respectively. In the Cd(II)-containing system, the same [Cd(p-XBT)]_n (2P = 2H) products were generated by both synthetic methods. Upon dehydration, 1P undergoes a “crystal-to-crystal” phase transition in the 170−185 °C temperature range, producing an anhydrous polycrystalline sample (1H). Both CPs 1H and 2H are isostructural and feature polymeric 3D metal-organic nets of the cds topological type, which are driven by the 4-linked metal and p-XBT²⁻ nodes. These compounds represent unique examples of coordination polymers derived from p-xylylene-bis(2-mercaptoacetic) acid, thus opening up the use of this flexible S,O-heterodonor building block in the design of polymeric metal-organic architectures.

Co(ii) coordination polymers constructed from a bent chiral linker: influencing framework topology using co-ligands

The reaction of a semi-rigid chiral ligand with Co(ii) and dipyridyl co-ligands of varying length yielded a series of 2D coordination frameworks, with the topology of the network mediated by the length of the co-ligands.

Two zinc(ii)-based coordination polymers with flexible dicarboxylate and pyridine mixed ligands: effect of π⋯π interactions on electrical activity

We synthesized two Zn(ii)-based 1D coordination polymers with paddle-wheel units using flexible 1,4-cyclohexanedicarboxylate linkers; these compounds exhibited electrical conductivity and Schottky barrier diode behavior.

A sensitive photoluminescent chemosensor for cyanide in water based on a zinc coordination polymer bearing ditert-butyl-bipyridine

Sensitive and direct sensing of cyanide in buffered aqueous solutions at pH = 7.0 by three new blue photoluminescent zinc-1,4-cyclohexanedicarboxylato coordination polymers bearing di-alkyl-2,2′-bipyridines has been achieved.

N Donor substituted acetylacetones – versatile ditopic ligands

Acetylacetone (2,4-pentanedione) derivatives with N donor substituents represent ditopic ligands with coordination sites of distinctly different Pearson hardness. Deprotonation of the acetylacetone (Hacac) moiety leads to O,O′ chelating monoanionic (acac) ligands suitable for coordination to hard cations. The softer N donor site(s) preferably act as nucleophiles towards softer partners. When the organic molecules are employed as linkers and coordinate via either site, they are often selective and allow to synthesize well-ordered heterometallic solids. This review addresses the derivatives of 17 pentanediones with nitrile, pyridyl and pyrazolyl moieties as N donor substituents, with an emphasis on structurally characterized compounds. Depending on the N donor substituents and the cations, O,O′ or N coordination will dominate. The nitrile-substituted compounds essentially behave as acetylacetones; they may easily O,O′ coordinate to a wide range of cations whereas N coordination is limited to AgI, CuI or, in the case of less soft cations, to longer and presumably weaker contacts, e.g. to the more distant sites in Jahn–Teller distorted CuII. In contrast, pyridyl-substituted pentanediones act as N donor ligands, regardless whether their (H)acac site is chelating a cation or not. The still scarcely explored pyrazolyl derivative shows the most complex coordination pattern: it may be deprotonated both at the acetylacetone and the pyrazol site, the latter affording N,N′ bridging ligands. In addition to N donor nucleophilicity, the distance between the alternative coordination sites and their mutual orientation are relevant for crystal engineering applications.

Structure modulation from unstable to stable MOFs by regulating secondary N-donor ligands

Four new Cd/Zn(ii) MOFs have been synthesized and structurally modulated from unstable to stable by regulating secondary N-donor ligands. Furthermore, YZ-10 shows excellent CO₂ selective uptake over CH₄ and N₂ and uncommon H₂ selective uptake over N₂ at 77 K.

Crystal structure of poly[[di-μ3-acetato-tetra-aqua-bis-(μ2-cyclo-hexane-1,4-di-carboxyl-ato)dilanth-an-um(III)] dihydrate]

The title compound, {[La2(CH3COO)2(C8H10O4)2(H2O)4]·2H2O} n or [La2(ac)2(e,a-cis-1,4-chdc)2(H2O)4]·2H2O, where ac is acetate and 1,4-chdc is cyclo-hexane-1,4-di-carboxyl-ate anion, is a binuclear lanthanum(III) complex. Each metal atom is deca-coordinated by four O atoms from two distinct 1,4-chdc2- ligands, four O atoms from three acetate groups and two O atoms from coordinated water mol-ecules to form a distorted bicapped square-anti-prismatic geometry. Two non-coordinated water mol-ecules are also present in the formula unit. The most remarkable feature of this compound is that it possesses a only cis conformation for cyclo-hexane-1,4-di-carb-oxy-lic acid, although the raw material consists of a mixture of cis and trans isomers. The μ3-η2:η2 coordination mode of the bridging acetate group and the flexible di-carboxyl-ate fragments of 1,4-chdc2- results in the formation of infinite two-dimensional lanthanide-carboxyl-ate layers within the crystal structure. The directionality of strong inter-molecular O-H⋯O and weak C-H⋯O inter-actions provides robustness to the layers, which leads to the construction of a three-dimensional supra-molecular network. The crystal studied was refined as a two-component twin.

Preorganized AgI Bimetallic Precursor with Labile Diphosphorus Ligands for a Programmed Synthesis of Organometallic-Organic Hybrid Polymers

An AgI dimer capped with labile organometallic diphosphorus ligands [Cp2 Mo2 (CO)4 (η2 -P2 )] (Cp=C5 H5 ) acts as a highly pre-organized molecular precursor to direct the construction of 1D or 2D, and 3D organometallic-organic hybrid coordination polymers upon reaction with ditopic pyridine-based linkers. The formation of the supramolecular aggregates can be controlled by the stoichiometry of the organic molecules, and the mechanism is supported by DFT calculations.

Semiconducting Coordination Polymers Based on the Predesigned Ternary Te-Fe-Cu Carbonyl Cluster and Conjugation-Interrupted Dipyridyl Linkers

A series of semiconducting cluster-incorporated Cu-based coordination polymers, namely, 1D zigzag polymers [{TeFe₃ (CO)₉ Cu₂ }(L)]_n (L=1,2-bis(4-pyridyl)ethane (bpea), 1; L=1,2-bis(4-pyridyl)ethylene (bpee), 5), 2D honeycomb-like polymers [{TeFe₃ (CO)₉ Cu}Cu(L)_2.5 ]_n (L=bpea, 2; L=bpee, 6), and 2D wave-like cation-anion polymer [{Cu₂ (L)₄ }({TeFe₃ (CO)₉ Cu}₂ (L))]_n (L=1,3-bis(4-pyridyl)propane (bpp), 4), as well as the macrocycle [{TeFe₃ (CO)₉ Cu₂ }₂ (bpp)₂ ] (3) have been quantitatively synthesized via the liquid-assisted grinding from the pre-designed cluster [TeFe₃ (CO)₉ Cu₂ (MeCN)₂ ] with conjugated or conjugation-interrupted dipyridyl linkers. Notably, the most conjugation-interrupted bpp-bridged polymer 4 exhibited extraordinary semiconducting characteristics with an ultra-narrow bandgap of 1.43 eV and a DC conductivity of 1.5×10^-2 Ω^-1  cm^-1 , which violates our knowledge, mainly attributed to the through-space electron transport via non-classical C-H⋅⋅⋅O(carbonyl) hydrogen bonds and aromatic C-H⋅⋅⋅π interactions. The incorporated Te-Fe-CO anions can not only provide numerous possibilities for secondary interactions within these Cu-based polymers but also serve as a redox-active coordination ligand to promote their conductivities. The intriguing structure-property relationships were studied by X-ray and DFT analyses and further demonstrated by significant change in the oxidation state of Cu atoms by XPS and Cu K-edge XANES.

Cadmium–1,4-cyclohexanedicarboxylato coordination polymers bearing different di-alkyl-2,2′-bipyridines: syntheses, crystal structures and photoluminescence studies

Cd(ii) polymers, in acetone, can be used as luminescent materials for detection of CH₃CN.

Controllable assembly of Cu(ii) coordination compounds based on a flexible zwitterionic benzimidazole–dicarboxylate ligand: synthesis, structural diversity, reversible SCSC transformation and magnetic properties

The reversible SCSC transformation of a paddle-wheel cluster to a 1D linear polymer could be accomplished.

Structural and spectral study of coordination of 4,4′-dimethoxy-2,2′-bipyridine toward Zn(II) and Cd(II) containing thiocyanato or azido ligands

Three new compounds of zinc(II) and cadmium(II) with the ligand 4,4′-dimethoxy-2,2′-bipyridine (4,4′-dmo-2,2′-bpy), including cis-[Zn(4,4′-dmo-2,2′-bpy)2(SCN)2] (1), cis-[Cd(4,4′-dmo-2,2′-bpy)2(SCN)2] (2), and [Cd3(4,4′-dmo-2,2′-bpy)3(N3)5(OAc)] n (3), have been obtained as white single crystals by the branched tube method and characterized by elemental analysis, FT-IR and 1H, 13C NMR spectroscopy, and X-ray crystallography. Single-crystal structure analyses of the isostructural complexes 1 and 2 showed distorted octahedral geometry for zinc(II) and cadmium(II) with ZnN6 and CdN6 environments. Complex 3 reveals a rare coordination polymer containing octahedrally coordinated cadmium(II) expanding to chains by two different bridging modes, including Cd‒O‒C‒O‒Cd and Cd‒N‒Cd.

Facile synthesis of one-dimensional organometallic-organic hybrid polymers based on a diphosphorus complex and flexible bipyridyl linkers

The selective synthesis of a series of new "ladderlike" one-dimensional organometallic-organic hybrid polymers is shown. The polymers are obtained from the reaction of the diphosphorus ligand complex [Cp2Mo2(CO)4(η(2)-P2)] with the copper salt [Cu(CH3CN)4]BF4 in the presence of flexible organic bipyridyl linkers in high selectivity. This unique behaviour is supported by DFT calculations.

Silver(I) coordination polymers assembled from flexible cyclotriphosphazene ligand: structures, topologies and investigation of the counteranion effects

The reactions of a flexible ligand hexakis(3-pyridyloxy)cyclotriphosphazene (HPCP) with a variety of silver(I) salts (AgX;X= NO3−, PF6−, ClO4−, CH3PhSO3−, BF4−and CF3SO3−) afforded six silver(I) coordination polymers, namely {[Ag2(HPCP)]·(NO3)2·H2O}n(1), {[Ag2(HPCP)(CH3CN)]·(PF6)2}n(2), {[Ag2(HPCP)(CH3CN)]·(ClO4)2}n(3), [Ag3(HPCP)(CH3PhSO3)3]n(4), [Ag2(HPCP)(CH3CN)(BF4)2]n(5) and {[Ag(HPCP)]·(CF3SO3)}n(6). All of the isolated crystalline compounds were structurally determined by X-ray crystallography. Changing the counteranions in the reactions, which were conducted under similar conditions ofM/Lratio (1:1), temperature and solvent, resulted in structures with different types of topologies. In complexes (1)–(6), the ligand HPCP shows different coordination modes with AgIions giving two-dimensional layered structures and three-dimensional frameworks with different topologies. Complex (1) displays a new three-dimensional framework adopting a (3,3,6)-connected 3-nodal net with point symbol {4.62}2{42.610.83}. Complexes (2) and (3) are isomorphous and have a two-dimensional layered structure showing the same 3,6L60 topology with point symbol {4.26}2{48.66.8}. Complex (4) is a two-dimensional structure incorporating short Ag...Ag argentophilic interactions and has a uninodal 4-connectedsql/Shubnikov tetragonal plane net with {44.62} topology. Complex (5) exhibits a novel three-dimensional framework and more suprisingly contains twofold interpenetrated honeycomb-like networks, in which the single net has a trinodal (2,3,5)-connected 3-nodal net with point symbol {63.86.12}{63}{8}. Complex (6) crystallizes in a trigonal crystal system with the space group R\bar 3 and possesses a three-dimensional polymeric structure showing a binodal (4,6)-connectedfshnet with the point symbol (43.63)2.(46.66.83). The effect of the counteranions on the formation of coordination polymers is discussed in this study.

Metal-controlled structural variations of coordination architectures constructed from flexible 1H-benzimidazole-1-propionic acid

Five low-dimensional coordination polymers and a novel discrete dodecametallic cage have been obtained from appropriate transition metals in combination with a flexible bifunctional benzimidazole carboxylic acid.

Alkyl linker effects on the coordination topology of ditopic di(2-pyridylmethyl)amine carboxylate ligands with ZnIIand CuII: polymersvs.macrocycles

Di(2-pyridylmethyl)amine carboxylates with short alkyl linkers afford coordination polymers whereas the longer homologues favour macrocyclic topologies.

Regulation of the pore size by shifting the coordination sites of ligands in two MOFs: enhancement of CO2 uptake and selective sensing of nitrobenzene

Two MOFs were constructed using azine functionalized and pyridyl based neutral ligands along with a V-shaped sdb linker, and exhibit highly efficient luminescence sensing for nitrobenzene and sorption selectivity for CO₂ over CH₄.

Microwave-assisted large scale synthesis of lanthanide metal–organic frameworks (Ln-MOFs), having a preferred conformation and photoluminescence properties

We have prepared 2 g Ln-MOF on a laboratory scale with high purity using microwave-assisted synthesis by changing the conformation of flexible ligand using Ln, which adopts only the preferred (energetically stable) conformation from green solvents (water and ethanol).

Synthesis, structures and magnetic properties in 3d-electron-rich isostructural complexes based on chains with sole syn–anti carboxylate bridges

A series of isostructures based on 2,2′,4,4′-biphenyltetracarboxylic acid have been synthesized via solvothermal reaction, whereas magnetic studies reveal the polymers with sole syn–anti carboxylate bridges show different magnetic behaviors of uniform chains.