Coordination Polymers as a Functional Material for the Selective Molecular Recognition of Nitroaromatics and ipso-Hydroxylation of Arylboronic Acids

We report the synthesis and structural characterization of two coordination polymers (CPs), namely; [{Zn(L)(DMF)₄ } ⋅ 2BF₄ ]_α (1) and [{Cd(L)₂ (Cl)₂ } ⋅ 2H₂ O]_α (2) (where L=N² ,N⁶ -di(pyridin-4-yl)naphthalene-2,6-dicarboxamide). Crystal packing of 1 reveals the existence of channels running along the b- and c-axis filled by the ligated DMF and lattice anions, respectively. Whereas, crystal packing of 2 reveals that the metallacycles of each 1D chain are intercalating into the groove of adjacent metallacycles resulting in the stacking of 1D loop-chains to form a sheet-like architecture. In addition, both 1 and 2 were exploited as multifunctional materials for the detection of nitroaromatic compounds (NACs) as well as a catalyst in the ipso-hydroxylation of aryl/heteroarylboronic acids. Remarkably, 1 and 2 showed high fluorescence stability in an aqueous medium and displayed a maximum 88% and 97% quenching efficiency for 4-NPH, respectively among all the investigated NACs. The mechanistic investigation of NACs recognition suggested that the fluorescence quenching occurred via electron as well as energy transfer process. Furthermore, the ipso-hydroxylation of aryl/heteroarylboronic acids in presence of 1 and 2 gave up to 99% desired product yield within 15 min in our established protocol. In both cases, 1 and 2 are recyclable upto five cycles without any significant loss in their efficiency.

Construction of a viologen-derived 2D material with photochromism, photoswitchable luminescence and inkless and erasable prints via sunlight irradiation

A Zn(ii) material based on thiophenedicarboxylate and viologen derivative mixed ligands is synthesized. Thanks to pyridinium unit embedded in its structure, the material exhibits a rapid photochromic response via sunlight irradiation.

Copper(i)-polymers and their photoluminescence thermochromism properties

Under hydro(solvo)thermal conditions, four organic bidentate bridging N,N'-donor ligands 1,3-bis(2-methylimidazol-1-yl)propane (L1), 4,4'-di(1H-imidazol-1-yl)-1,1'-biphenyl (L2), 1,2-bis(2-methyl-1H-imidazol-1-ylmethyl)benzene (L3) and 5,6,7,8-tetrahydroquinoxaline (L4) were employed to react with CuBr/CuI, generating four 2-D layered copper(i)-polymer coordination polymer materials [Cu2Br2(L1)] 1, [CuI(L2)] 2, [CuI(L3)] 3 and [CuI(L4)0.5] 4. In 1-4, different Cu-X motifs are found: a cubic Cu4Br4 core in 1; a castellated Cu-I single chain in 2; a rhombic Cu2I2 core in 3; and a staircase-like Cu-I double chain in 4. The 2-D layer networks of 1-3 can all be simplified into a simple 44 topology (planar for 1 and 3; wave-like for 2), while the 2-D layer network of 4 has a 63 topology. The photoluminescence behaviors of 1-4 under a UV lamp suggest that 1 and 2 possess fluorescence thermochromism properties. Under the UV lamp, with the decrease in temperature, (i) 1 exhibits a yellow-to-red emission; (ii) 2 exhibits a yellow-to-green emission; (iii) 3 always emits green light; and (iv) 4 never emits light. These are further confirmed by their emission spectra. From 297 K to 77 K, the emission of 1 exhibits a large red shift from 561 nm to 623 nm; the emission of 2 exhibits a large blue shift from 571 nm to 515 nm; only a minor red shift is observed for the emission of 3; and no peaks appear in the emission spectra of 4. The crystal data of 1 and 2 at different temperatures have been collected for revealing the origination of their fluorescence thermochromism properties. Based on the above investigations, the effect of the rigidity/flexibility of the organic ligand on the fluorescence thermochromism properties of copper(i)-polymer coordination polymer materials is discussed. The quantum yields at 297 K and the photoluminescence lifetimes at 297 K and 77 K for 1-3 were also measured for better understanding their photoluminescence properties.

Crystal structure of catena-poly[tetraaqua(μ2-4-(1H-imidazol-1-yl)pyridine-κ2N:N′))zinc(II)] thiophene-2,5-dicarboxylate, C14H17N3O8ZnS

C14H17N3O8ZnS, triclinic, P1̄ (no. 2), a = 6.3962(5) Å, b = 6.9439(7) Å, c = 20.4208(19) Å, α = 93.040(8)°, β = 96.337(7)°, γ = 110.970(8)°, V = 837.54(13) Å3, Z = 2, Rgt(F) = 0.0390, wRref(F2) = 0.0769, T = 288(10) K.

Crystal structure of poly[(μ2-2-carboxy-5-nitroisophthalato-κ2 O:O′)-(μ2-4-((1H-imidazol-1-yl)methyl)pyridine-κ2 N:N′)zinc(II)], C18H12N4O8Zn

C18H12N4O8Zn, monoclinic, P21/n (no. 14), a = 9.5472(6) Å, b = 21.1662(10) Å, c = 9.6909(6) Å, β = 110.525(7)°, V = 1834.0(2) Å3, Z = 4, R gt(F) = 0.0371, wR ref(F 2) = 0.0809, T = 291.2(3) K.

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.

A multifunctional Ni(ii) coordination polymer: synthesis, crystal structure and applications as a luminescent sensor, electrochemical probe, and photocatalyst

A new Ni(ii) complex containing 2,5-dichloroterephthalate and rigid bis(imidazole) ligands, which manifests multifunctional properties, has been synthesized and characterized.

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.

Crystal structure of 4-nitro-thiophene-2-carboxylic acid, a structure with a Z′ = 4, C5H3NO4S

C5H3NO4S, monoclinic, P21/c, a = 11.7169(18) Å, b = 8.2671(12) Å, c = 28.478(4) Å, β = 93.396(2)°, Z = 16, F(000) = 1408, V = 2753.6(7) Å3, R gt (F) = 0.039, wR ref (F 2 ) = 0.107, T = 296 K.

Crystal engineering of cadmium coordination polymers decorated with nitro-functionalized thiophene-2,5-dicarboxylate and structurally related bis(imidazole) ligands with varying flexibility

Five bis(imidazole) ligand modulated cadmium coordination polymers based on a new nitro-functionalized thiophene-2,5-dicarboxylate ligand or 4-nitro-thiophene-2-carboxylic acid involving in situ ligand synthesis.

Supramolecular metallacycles with a ‘pseudo double-paracyclophane’ structure based on flexible π-conjugated linkers

Coordination-driven supramolecular synthesis of new supramolecular π-stacked metallacycles based on flexible π-conjugated linkers and having a ‘pseudo double-paracyclophane’ structure is presented.