Complexation of 4,4′-di(tert-butyl)-5-ethynyl-2,2′-bithiazole with mercury(II) ion: Synthesis, structures and analytical applications

An Overview of the Synthesis and Antimicrobial, Antiprotozoal, and Antitumor Activity of Thiazole and Bisthiazole Derivatives

Thiazole, a five-membered heteroaromatic ring, is an important scaffold of a large number of synthetic compounds. Its diverse pharmacological activity is reflected in many clinically approved thiazole-containing molecules, with an extensive range of biological activities, such as antibacterial, antifungal, antiviral, antihelmintic, antitumor, and anti-inflammatory effects. Due to its significance in the field of medicinal chemistry, numerous biologically active thiazole and bisthiazole derivatives have been reported in the scientific literature. The current review provides an overview of different methods for the synthesis of thiazole and bisthiazole derivatives and describes various compounds bearing a thiazole and bisthiazole moiety possessing antibacterial, antifungal, antiprotozoal, and antitumor activity, encouraging further research on the discovery of thiazole-containing drugs.

Influence of ligand chemistry on silver nanoparticles for colorimetric detection of Cr3+ and Hg2+ ions

In this work, we describe the role of ligand chemistry on the surfaces of silver nanoparticles (Ag NPs) for tuning their analytical applications. The citrate and melamine (MA) molecules were used as ligands for the surface modification of Ag NPs. The addition of Cr³⁺ ion in citrate-Ag NPs (Cit-Ag NPs) and of Hg²⁺ ion in melamine-Ag NPs (MA-Ag NPs) cause Ag NPs aggregation, and are accompanied by a color change and a red-shift. The resulting distinctly visual readouts are favorable for colorimetric detection of Cr³⁺ and Hg²⁺ ions. Under optimal conditions, the linear ranges are observed in the concentration ranges of 1.0-50.0 and of 10.0-100.0 μM, and with detection limit of 0.52 and 1.80 μM for Cr³⁺ and Hg²⁺ ions. The simultaneous detection of Cr³⁺ and Hg²⁺ ion is driven by the changing the ligand chemistry on the surfaces of Ag NPs that allows to tune their specific interactions with target analytes. Finally, the functionalized Ag NPs were successfully applied to detect Cr³⁺ and Hg²⁺ ions in water samples with satisfactory recoveries.

A red-emitting fluorescent probe for the detection of Hg2+ in aqueous medium, living cells and organisms with a large Stokes shift

A vinethene-based fluorescent probe has been developed for the sensitive and selective detection of Hg²⁺ with a low detection limit, a red emission and a large Stokes shift. The probe has been successfully applied to detect Hg²⁺ in aqueous solutions, living cells and organisms.

Application of Starch-Stabilized Silver Nanoparticles as a Colorimetric Sensor for Mercury(II) in 0.005 mol/L Nitric Acid

A sensitive and selective Hg2+optical sensor has been developed based on the redox interaction of Hg2+with starch-coated silver nanoparticles (AgNPs) in the presence of 0.005 mol L−1HNO3. The relative intensity of the localized surface plasmon absorption band of AgNPs at 406 nm is linearly dependent on the concentration of Hg2+with positive slope for the concentration range 0–12.5 μg L−1and negative slope for the concentration range 25–500 μg L−1. Experiments performed demonstrated that metal ions (Na+, K+, Mg2+, Ca2+, Pb2+, Cu2+, Zn2+, Cd2+, Fe3+, Co2+, and Ni2+) do not interfere under the same conditions, due to the absence of oxidative activity of these ions, which guarantees the high selectivity of the proposed optical sensor towards Hg2+. The limits of detection and quantification were found to be 0.9 µg L−1and 2.7 µg L−1, respectively, and relative standard deviations varied in the range 9–12% for Hg content from 0.9 to 12.5 μg L−1and 5–9% for Hg levels from 25 to 500 μg L−1. The method was validated by analysis of CRM Estuarine Water BCR505. A possible mechanism of interaction between AgNPs and Hg2+for both concentration ranges was proposed on the basis of UV-Vis, TEM, and SAED analyses.

Spirolactone and spirothiolactone rhodamine-pyrene probes for detection of Hg²⁺ with different sensing properties and its application in living cells

Two new rhodamine B-based fluorescent probes PyRbS and PyRbO containing pyrene moiety were designed and synthesized. Both of the probes showed colorimetric and fluorometric sensing abilities for Hg(2+) with high selectivity over other metal ions. The binding analysis using Job's plot suggested 1:1 stoichiometry for the complexes formed for Hg(2+). Compared with PyRbO, the PyRbS showed higher selectivity and sensitivity due to the thiophilic property of Hg(2+) ion. The PyRbS exhibited the linear fluorescence quenching to Hg(2+) in the range of 0.3 to 4.8 μM (λ(ex)=365 nm) and 0.3 to 5.4 μM (λ(ex)=515 nm), and the detection limit was 0.72 μM. Moreover, ratiometric changes of PyRbS with Hg(2+) in absorption spectrum were observed, which could not be obtained in the combination of PyRbO with Hg(2+). In addition, the methyl thiazolyl tetrazolium (MTT) assay demonstrated that RbPyS had low cytotoxicity and was successfully used to monitor intracellular Hg(2+) levels in living cells.

Crystal structure of 3-[4-(1H-imidazol-1-yl)phenyl]-2-(4-nitrophenyl)prop-2-enenitrile

In the title compound, C₁₈H₁₂N₄O₂, which has a delocalized D—π—A electronic structure, the dihedral angles between the central benzene ring and the planes of the pendant imidazole and nitro­benzene rings are 37.65 (9) and 4.96 (7)°, respectively. In the centrosymmetric crystal structure, mol­ecules are linked by weak C—H⋯O inter­actions, generating [001] C(6) chains.

A simple approach for measuring emission patterns of vapor phase mercury under temperature-controlled conditions from soil

In an effort to study the possible effects of climate change on the behavior of atmospheric mercury (Hg), we built a temperature–controlled microchamber system to measure its emission from top soils. To this end, mercury vapour emission rates were investigated in the laboratory using top soil samples collected from an urban area. The emissions of Hg, when measured as a function of soil temperature (from ambient levels up to 70°C at increments of 10°C), showed a positive correlation with rising temperature. According to the continuous analyses of the Hg vapor given off by the identical soil samples, evasion rate diminished noticeably with increasing number of repetitions. The experimental results, if examined in terms of activation energy (Ea), showed highly contrasting patterns between the single and repetitive runs. Although the results of the former exhibited Ea values smaller than the vaporization energy of Hg (i.e., <14 Kcal mol⁻¹), those of the latter increased systematically with increasing number of repetitions. As such, it is proposed that changes in the magnitude of Ea values can be used as a highly sensitive criterion to discriminate the important role of vaporization from other diverse (biotic/abiotic) processes occurring in the soil layer.

Langmuir-Blodgett Films of Dinuclear Mercury(II)-Containing Diethynylcarbazole/Polyoxometalate Hybrids: Film Characterization Studies and Potential Optoelectronic Applications

A new family of organometallic/inorganic hybrid Langmuir-Blodgett (LB) films, consisting of organometallic mercury acetylide (OMA) as the π-conjugated organometallic molecule and polyoxometallate (POM, POM = K5BW12O40 or Na5IMo6O24) of the Keggin and Anderson structures as the inorganic composite and docosanoic acid (DA) as the auxiliary film-forming agent, were prepared and well characterized by π–A isotherms, UV-vis absorption and photoluminescence spectra, atomic force microscopy imaging, scanning tunnelling microscopy, and low-angle X-ray diffraction. Our experimental results indicate that stable and well defined monolayer Langmuir and LB films are formed in pure water and POM subphases. There is a quenching effect in the luminescence intensity of the mercury complex when it is made into the LB films due to the enhanced aggregation phenomenon. These alkynylmercury(ii) based LB films exhibit interesting electrical conductivity behaviour, dependent of the characteristics of the POM used. They all reveal decent electrical conductivity, and the tunnelling current can reach ±100 nA when the voltage is set at –5 to +5 V.