Construction of a series of Zn(II) and Cd(II) coordination polymers bearing 1,3-bis(benzimidazol-1-yl)-2-propanol ligands: Syntheses, crystal structures, and sensing properties

Anticancer, antimicrobial and photocatalytic activities of a new pyrazole containing thiosemicarbazone ligand and its Co(III) and Ni(II) complexes: Synthesis, spectroscopic characterization and X-ray crystallography

A new pyrazole based thiosemicarbazone ligand, 5-methyl-3-formylpyrazole-N(4)-isopropylthiosemicarbazone, (HMPzNHPri) (compound I), and its cobalt(III) and nickel(II) complexes, [Co(MPzNHPri)2]Cl (compound II) and [Ni(HMPzNHPri)2]Br2 (compound III), respectively, have been synthesized and characterized through various physico-chemical and spectroscopic studies. Both the reported Co(III) and Ni(II) complexes are cationic in nature and behave as 1:1 and 1:2 electrolytes in MeOH, respectively. Electronic spectral features of the complexes have classified them as distorted octahedral ones. IR spectral data (4000-450 cm-1) have suggested a monoprotic tridentate (NNS) function of compound I coordinating to the Co(III) ion via the pyrazolyl (tertiary) ring nitrogen, azomethine nitrogen and thiolato sulphur atom; while for compound III, compound I has been found to act as neutral NNS tridentate one, coordinating to Ni(II) via the pyrazolyl iminic nitrogen, azomethine nitrogen and thioketo sulphur. Structural features of all the compounds are confirmed by the single crystal X-ray data. All the compounds reported here have been found to exhibit significant photocatalytic activity towards degradation of Methylene Blue (MB) under UV radiation. Anticancer activity of all the three compounds against cancer cell lines (HeLa and A549) and a normal cell line (HEK293) have been investigated. Compound II has been found to be more efficient against the human cervical cancer cell (HeLa) and the lung cancer cell (A549) than compounds I and III. The ligand and both the complexes display potential activities against both gram-positive (Bacillus subtilis MTCC 7193) and gram-negative bacteria (E. coli MTCC 1610).

Highly Selective Ratiometric Sensors for Pb2+ Based on Luminescent Zn(II)-Coordination Polymers with Thiophenedicarboxylate. Crystal Structures and Spectroscopic Studies

The development of luminescent coordination polymers for the selective sensing of Pb2+ in water constitutes an active area of research that impacts analytical, environmental, and inorganic chemistry. Herein, two novel water-stable 2D Zn-coordination polymers {[Zn2(H2O)2(tdc)2(bpy)]·(H2O)}n 1 and [Zn(tdc)(tmb)]n 2 (tdc = thiophenedicarboxylate; bpy = 4,4'-bipyridine and tmb = 4,4'-trimethylenebipyridine) were synthesized, structurally determined by single crystal X-ray diffraction, and studied in-depth as luminescent sensors for a series of cations (Ca2+, Mg2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+ Cd2+, Hg2+ and Pb2+) in 20% aqueous ethanol. These Zn-polymers possess photostability in 20% aqueous ethanol with a strong emission at 410 upon excitation at 330 nm and quantum yields of around Φ = 0.09. Under these conditions, Pb+2 can be efficiently sensed with polymer 2 through a fluorescent ratiometric response with selectivity over common interfering metal ions such as Cu2+, Cd2+ and Hg2+ in the micromolar concentration range (detection limit = 1.78 ± 10 μM). Such selectivity/affinity of Pb2+ over Hg2+ for luminescent chemosensors is still rare. On the basis of spectroscopic tools (1H NMR, far ATR-IR, PXRD), the X-ray crystal structure of 2, and Scanning Electron Microscopy with Energy-Dispersive X-ray Spectroscopic analysis, the ratiometric fluorescent response is proposed via an efficient metal-ion exchange driven through interactions between thiophenedicarboxylate rings and Pb2+ ions. The use of flexible luminescent Zn-coordination polymers as sensors for selective and direct detection of Pb2+ in aqueous media has been unexplored until now.

Activation of Cadmium–Imidazole Buffering Coordination Polymer by Sulfur-Doping for the Enhancement of Photocatalytic Degradation of Cationic and Anionic Dyes Under Visible Light

The buffering Cadmium–Imidazole Coordination Polymer (Cd–Im-CP) was synthesized hydrothermally from cadmium chloride and imidazole at 70 °C and then was subjected to doping- by the non-metal sulfur using Na2S solution as a novel modification strategy to produce S–Cd–Im CPs. To investigate doping nature and its effects, Cd–Im CP and S–Cd–Im CPs were characterized applying different analyses techniques, FTIR, Raman, PXRD, SEM/EDX, TGA, and UV–Vis DRS analyses. Characterizations showed the successful chemical doping of sulfur. The inclusion of sulfur within chemical CP structure caused narrowing of material’s bandgap from 4.55 and 3.4 eV to 4.25 and 2.35 eV for S–Cd–Im CPs allowing it for photoresponse towards Visible-light. Both Cd–Im CP and S–Cd–Im CPs were applied for photocatalytic degradation of the selected dyes methylene blue (MB),and methyl orange (MO) employing visible and UV irradiations considering three different initial pH levels to investigate the consequence of sulfur doping. After eliminating the photolysis effect, the best degradation by S–Cd–Im CPs was recorded for MB at initial pH 4 being 13 fold that is for Cd–Im CP. The highest apparent turnover frequencies are 1.2 × 10−3 h−1 for MB at initial pH 10 and 1.03 × 10−4 h−1 for MO at initial pH 4 are given by 10S–Cd–IM CP under Visible-light. Generally, S–Cd–Im CPs remarkably improved photocatalysis degradation of both the dyes for all initial pH levels under Visible-light.

Series of highly stable Cd(ii)-based MOFs as sensitive and selective sensors for detection of nitrofuran antibiotic

The oxygen atom of the MOF ether-bridging group acts as a Lewis base site, improving the connection and allowing the detection of 10 antibiotics through the fluorescence quenching effect.

Multidimensional luminescent cobalt(ii)-coordination polymers as sensors with extremely high sensitivity and selectivity for detection of acetylacetone, benzaldehyde and Cr2O72−

Three new ternary cobalt(ii) CPs were synthesized. 1 exhibits a 3D pcu framework, 2 possesses a 2D hcb layer and 3 is a 1D chain structure. 1, 2, and 3 can be effective luminescent probes for sensing acetylacetone, benzaldehyde and Cr₂O₇²⁻ ions.