Three new coordination polymers (CPs) of coordinated isoniazid (INH) to Zn(II) with succinic acid (H 2 succ), fumaric acid (H 2 fum), and terephthalic acid (H 2 bdc) as organic linker, [Zn(INH)(succ)] n (1), [Zn(INH)(fum)] n (2), and [Zn(INH)(bdc)] n (3), respectively, have been characterized. The structure determination by the single crystal X-ray diffraction technique shows a ZnN 2 O 4 distorted octahedral geometry, and the 1D chain is constituted via the INH and carboxylate coordination along with the hydrogen bonding (N−H•••O) which comprises a 2D structure. The CPs, 1 and 2, are isostructural and fabricate supramolecular networks by inclined intercatenation of two 2D layers, while 3 shows parallel intercatenation. The electrical conductivity and Schottky barrier diode behavior have been established by the charge transport mechanism of the compounds at the quasi-Fermi level state. The analysis indicates that the compound 1 has the highest mobility (2.53 × 10 −10 m 2 V −1 s −1 ) than 2 (1.86 × 10 −10 m 2 V −1 s −1 ) and 3 (1.89 × 10 −10 m 2 V −1 s −1 ) and the highest electrical conductivity (2.26 × 10 −4 S m −1 ) than the others (1.12 × 10 −4 S m −1 (2) and 1.25 × 10 −4 S m −1 (3)). DFT computation of the structural motif of CPs has calculated the band gap (ΔE: 3.93 eV (1), 4.45 eV (2), 4.26 eV (3)), which supports the progression of conductivity.
Coordination polymers are useful materials in different fields of applications, including the development of supramolecular electrical devices for the use of renewable energy sources. In this work, we have designed two new classes of mixed-ligand one-dimensional coordination polymers (1D, acetylenedicarboxylato; Succ 2− , succinato; PBT, 2-pyridin-4-ylbenzothiazole) and characterized them by elemental analysis, infrared spectra (IR), single-crystal X-ray diffraction data, powder X-ray diffraction (PXRD), and thermogravimetric analysis (TGA) data. In the structural motif Zn(II) is bridged by an aliphatic dicarboxylato ligand (ADC/ Succ) and two axial positions are occupied by pyridyl-N of PBT along with water coordination. ADC acts as a monodentate carboxylato-O ligand in compound 1, whereas in 2 Succ serves as a carboxylato-O,O chelator. Compounds 1 and 2 are both isostructural and construct 3D supramolecular networks by hydrogen bonds (bonding) and π•••π interactions along with weak C−H•••π interactions. Fascinatingly, compound 1 exhibits an ∼700 times higher Schottky barrier diode (SBD) electrical conductivity (1.31 × 10 −2 S m −1 ) in comparison to compound 2 (1.80 × 10 −5 S m −1 ). The impedance electrical conductivities of 1 (1.22 × 10 −4 S m −1 ) and 2 (3.24 × 10 −6 S m −1 ) differ significantly; in addition, the direct current conductivities are 1.08 × 10 −4 S m −1 (1) and 5.55 × 10 −6 S m −1 (2). To shed light on the charge transport mechanism of the compounds, the mobility, transit time, and density of states at a quasi-Fermi level have been evaluated. Linear dicarboxylato bridging with an sp-hybrid acetylene motif may be the reason for faster charge flow in 1 in comparison to the sp 3 hybrid nonlinear succinato bridging compound 2.
Four new mixed-ligand divalent coordination polymers (CPs) [Cu2(muco)2(4-clpy)2] (1), [Cu2(muco)2(4-brpy)2] (2), [Zn2(bdc)2(4-clpy)2] (3), and [Zn2(bdc)2(4-brpy)2] (4) (H2muco = trans,trans-muconic acid or 1,3-butadiene-1,4-dicarboxylic acid; H2bdc = 1,4-benzene dicarboxylic acid; 4-clpy = 4-chloropyridine and 4-brpy = 4-bromopyridine) have been synthesized and well characterized by elemental analysis, infrared spectra, single-crystal X-ray diffraction techniques, powder X-ray diffraction patterns, and thermogravimetric analysis. All the compounds 1–4 have a two-dimensional (2D) coordination polymeric sheet structure. Of these, 1 and 2 are isotypical and form a 3D supramolecular aggregation based on type-I halogen–halogen interactions (Cl···Cl or Br···Br) and have an impact on CO2 sorption properties. For the first time, halogen–halogen interactions have been used as a tool in the construction of high-dimensional CPs for sorption studies. However, analogous compounds 3 and 4 are expanded to 3D supramolecular structures based on π···π interactions. These compounds have no halogen–halogen interactions and hence become nonporous toward CO2 sorption. It appears that the halogen–halogen interactions between the 2D sheets are desirable for the uptake of CO2 gas.
The porous materials are efficient storage and exchange systems of small molecules and ions. Some of the porous materials may be used as an efficient storage system of iodine. Herein, a honeycomb (hcb)-type 2D+2D (2D = two-dimensional), parallel polycatenated Porous Polycatenated Coordination Polymer (PPCP) {[Cd2I2(BDC)2(INH)2]·(2DMF)(H2O)} n , 1 (INH, isoniazid; H2BDC, terephthalic acid; DMF, dimethylformamide) is characterized that reversibly uptakes I2 from organic medium (more than 98%). The single-crystal X-ray structure determination reveals the CdIN2O3 distorted octahedral geometry, and the microporous channel (∼1.7 nm) is generated by polycatenation along with the supramolecular interaction. On thermal treatment at 120 °C the polymer, 1, loses solvents, while the crystalinity is reserved. The solvent-free activated state of the coordination polymer, [Cd2I2(BDC)2(INH)2] n , 1′, adsorbs N2, and the adsorption–desorption analysis displayed the increase in porosity to mesoporous range (∼14.7 nm) with very high specific Brunauer–Emmett–Teller surface area, which may be due to the rise in interparticle void space. Iodine (I2) sorption studies of mesoporous architecture of 1′ show high I2 removal efficiency (98.9%), which is revealed from the reversible iodine uptake kinetics study. Typically, uptake of three moles of I2 per unit cell associated with color change from colorless to brown is discernible from thermal analysis. Interestingly, the iodine-loaded polymer (I 2 @1′) shows ∼1.5 times enhancement in electrical conductivity compared to 1′ only. The optical band gap obtained from density functional theory (DFT) calculation and the experimental values are 1, 3.48 eV (DFT), 3.70 eV (experimental) and I 2 @1′, 3.19 eV (DFT), 3.50 eV (experimental). The lowering of band gap after I2 sorption is presumably due to the interaction of I2 with Cd–I (Cd–I···I–I) in hcb core, which was evidenced from Raman spectra analysis.
Drinking water quality management and sustainable environment to water bodies are a major concern to public health engineering departments. Inorganic phosphate (Pi), one of the major inorganic pollutants, is addressed for the last two decades regarding trace quantity detection. Over the past few years, a large number of fluorescent metal−organic frameworks (F-MOFs) have been studied to explore the desirable method for selective water analysis. In this article, a Zn− anion by a "turn-off" fluorescent sensing technique. Single-crystal X-ray analysis accounts that the asymmetric unit is constituted of two different Zn(II) centers by PCDF-INH, and the bridging group BDC 2− ions are responsible for the generation of the helical polymer and the biporous structures (14.807 × 13.096 Å 2 and 24.905 × 24.932 Å 2 ). The compound, 1, exhibits strong emission at 505 nm in CH 3 OH−H 2 O solution and is "turn-off" upon the addition of H 2 PO 4 − . The selectivity and specificity for H 2 PO 4 − have been checked in the presence of 15 different anions, including different phosphates (PO 4 3− , HPO 4 2− , P 2 O7 4 − ). The entire sensing activity of 1 is examined by spectrofluorometric method, 1 H NMR titration, PXRD analysis, and bioimaging study, and the limit of detection is 3.903 μM. However, in vitro biosensing analysis confers that F-MOF (1) is sensable toward the H 2 PO 4 − ion at a trace level in the human lung fibroblast cells and human liver cancer cell line Hep G2.
Naphtheledicarboxylato ((NDC 2− ) bridged coordination polymers (CPs) along with (E)-1-methyl-2-(p-chlorophenylazo)imidazole (ClPai-Me) coordination to Co(II), [Co(∝-NDC) 0.5 (∝ 4 -NDC) 0.5 (ClPai-Me)]•0.5H 2 O (1), and to Zn(II), [Zn(∝-NDC) 0.5 (∝ 4 -NDC) 0.5 (ClPai-Me)]•0.5H 2 O (2), have been characterized. In the single crystal X-ray structure of 1, ClPai-Me chelates to the Co(II) ion by N(azo) and N(imidazolyl), whereas in compound 2, it acts as a monodentate N(imidazolyl) donor to the Zn(II) ion. The coordination atmosphere around Co(II) in the 1 ion is distorted octahedral CoN 2 O 4 , whereas in the case of 2, it is distorted square pyramidal ZnNO 4 . Compounds 1 and 2 exhibit the righthanded (P) and left-handed (M) one-dimensional helical chain. NDC −2 is serving as a bridge between two M(II) ions to constitute μ-NDC and four M(II) ions to construct μ 4 -NDC to assemble threedimensional polymers. Upon UV light (369 nm) irradiation, compound 2 shows trans-to-cis isomerization of -NN−C 6 H 4 −Clp both in the solid and solution state but 1 remains silent. Prolonged light irradiation in the solid state (film phase) does not change the coordinated ClPai-Me in complexes 1 and 2, whereas the free stage of ClPai-Me undergoes photoreduction of the −NN− bond and forms azo radicals with a concomitant permanent color change. The persistence of the radical has been characterized by electron paramagnetic resonance spectroscopy in the solid state at g = 2.009. The effective magnetic moment of 1 is 4.17 μ B at 300 K, Co(II) ion of S = 3/2.
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