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Zinc ion (Zn2+) is an important and a most useful biological trace nutrient responsible for the activity of several enzymes. Zn2+ concentrations in the environment as well as in the human body increase beyond permissible limits as a consequence of its mining and widespread industrial applications. Such excess Zn2+ concentrations are toxic to humans and many aquatic organisms. The magnetic inertness and spin paired electronic configuration of Zn2+ makes it hard to detect by common analytical techniques. Therefore, fluorometric detection using chemosensor is the most effective tool for the environmental and biological detection of Zn2+. We have developed a novel pyridine-constrained bis(triazole-linked hydroxyquinoline) ligand as a reversible fluorescent chemosensor for Zn2+. The symmetrical ligand is highly selective for Zn2+ and fluoresces brightly upon complexation compared with other metal ions based on chelation-enhanced fluorescence mechanism. Interestingly, free ligand can be regenerated by treating the ligand–Zn2+ complex with aqueous ammonia. 相似文献
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An efficient, straightforward and environmentally benign process has been developed for the synthesis of fluorenone and 1-tetralone derivatives using cyclic 1,3-dione, malononitrile and dialkylacetylenedicarboxylate as starting materials in aqueous medium. The reaction is favoured in presence of resorcin[4]arene which is effective as a reusable organocatalyst. The catalyst has been easily synthesized and characterized by 1H, 13C NMR, IR, XRD and HRMS analyses. Resorcin[4]arene afforded the resulted products in a shorter time and in good yields. The recyclability of the catalyst was established up to 6th cycle by FT-IR and SEM images. 相似文献
15.
Dr. Mostakim SK Dr. Soumitra Barman Shounik Paul Ratnadip De Dr. S. S. Sreejith Dr. Helge Reinsch Dr. Maciej Grzywa Dr. Norbert Stock Prof. Dr. Dirk Volkmer Dr. Shyam Biswas Prof. Dr. Soumyajit Roy 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(12):4098-4107
A Zr-based metal-organic framework has been synthesized and employed as a catalyst for photochemical carbon dioxide reduction coupled with water oxidation. The catalyst shows significant carbon dioxide reduction property with concomitant water oxidation. The catalyst has broad visible light as well as UV light absorption property, which is further confirmed from electronic absorption spectroscopy. Formic acid was the only reduced product from carbon dioxide with a turn-over frequency (TOF) of 0.69 h−1 in addition to oxygen, which was produced with a TOF of 0.54 h−1. No external photosensitizer is used and the ligand itself acts as the light harvester. The efficient and selective photochemical carbon dioxide reduction to formic acid with concomitant water oxidation using Zr-based MOF as catalyst is thus demonstrated here. 相似文献
16.
Debanjan Chakraborty Shyamapada Nandi Rahul Maity Dr. Radha Kishan Motkuri Dr. Kee Sung Han Sean Collins Dr. Paul Humble Dr. James C. Hayes Prof. Tom K. Woo Dr. Ramanathan Vaidhyanathan Dr. Praveen K. Thallapally 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(55):12544-12548
Molecular confinement plays a significant effect on trapped gas and solvent molecules. A fundamental understanding of gas adsorption within the porous confinement provides information necessary to design a material with improved selectivity. In this regard, metal–organic framework (MOF) adsorbents are ideal candidate materials to study confinement effects for weakly interacting gas molecules, such as noble gases. Among the noble gases, xenon (Xe) has practical applications in the medical, automotive and aerospace industries. In this Communication, we report an ultra-microporous nickel-isonicotinate MOF with exceptional Xe uptake and selectivity compared to all benchmark MOF and porous organic cage materials. The selectivity arises because of the near perfect fit of the atomic Xe inside the porous confinement. Notably, at low partial pressure, the Ni–MOF interacts very strongly with Xe compared to the closely related Krypton gas (Kr) and more polarizable CO2. Further 129Xe NMR suggests a broad isotropic chemical shift due to the reduced motion as a result of confinement. 相似文献
17.
Heinz J. Robota Laura A. Richard Soumitra Deshmukh Steve LeViness Daniele Leonarduzzi Diarmid Roberts 《Catalysis Surveys from Asia》2014,18(4):177-182
Each process configuration for practicing the Fischer–Tropsch synthesis places demands particular to that configuration on the catalyst to be used. We discuss how a particular catalyst, prepared by the OMX (organic matrix combustion) method, when used in conjunction with the Velocys microchannel reactor system, results in a very stable, high performance Fischer–Tropsch synthesis system. With the ability to remove heat far more effectively than a conventional reactor system, this microchannel reactor requires a catalyst with much higher volumetric reactive site density. Further, with such a high volumetric reaction rate, mass transfer effects will be important in both the observed activity and selectivity of the operating catalyst. Nevertheless, the catalyst prepared using the OMX method exhibits an apparent turnover frequency which is considerably higher than reported for other catalysts in the literature. In addition to high activity, an economically useful catalyst must exhibit a stable, high selectivity for liquid products and be able to recover near-fresh performance using a regeneration approach which can be carried out with the catalyst in-place. An example of such a stable, multiply regenerated catalyst is given. Finally, further development has focused on a catalyst with even higher C5+ selectivity. 相似文献
18.
An analytical study on nonlinear evolution of Langmuir waves in warm electron-positron-dusty plasmas is presented. The massive dust grains of either positively or negatively charged are assumed to form a fixed charge neutralizing background. A perturbative analysis of the fluid-Maxwell's equations confirms that the excited Langmuir waves phase-mix and eventually break, even at arbitrarily low amplitudes. It is shown that the nature of the dust-charge as well as the amount of dust grains can significantly influence the Langmuir wave phase-mixing process. The phase-mixing time is also found to increase with the temperature. 相似文献
19.
Qurratul Ain Sarvesh Kumar Pandey Om Prakash Pandey Soumitra Kumar Sengupta 《应用有机金属化学》2016,30(2):102-108
A series of neodymium(III) and samarium(III) complexes of type [Ln(L)Cl(H2O)3] have been synthesized with Schiff bases (LH2) derived from 3‐(phenyl/substituted phenyl)‐4‐amino‐5‐mercapto‐1,2,4‐triazoles and isatin. The structures of the complexes were established using elemental analysis, molar conductivities, magnetic moments, infrared, NMR (1H, 13C) and UV–visible spectra, X‐ray diffraction and mass spectrometry. The thermal behaviour of these compounds under non‐isothermal conditions was investigated using thermogravimetry and differential thermogravimetry. The intermediates obtained at the end of various thermal decomposition steps were identified from elemental analysis and infrared spectral studies. All the ligands and their complexes were also screened for their antibacterial activity against Staphylococcus aureus and Bacillus subtilis and antifungal activity against Aspergillus niger, Aspergillus flavus and Colletotrichum capsici. The screening results were correlated with the structural features of the compounds. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
20.
Shyamaprosad Goswami Abhishek Manna Sima Paul Avijit K. Das Prasanta K. Nandi Anup Kumar Maity Partha Saha 《Tetrahedron letters》2014
5(Benzothiazol-2-yl)-4-hydroxyisophthalaldehyde (BHI), an intense ESIPT containing molecule in mixed media loses its properties due to resonance-assisted H-bond (RAHB) in absolute water. Due to resonance-assisted H-bond the o-aldehyde is more reactive than the other one. With addition of cysteine/homocysteine into this solution the o-aldehyde group gets transformed into thiazolidine/thiazine ring, respectively, and the phenolic proton becomes free enough for transfer to nitrogen of the benzothiazole ring in excited state, that is, the ESIPT of BHI is turned on. Thus we can detect cysteine/homocysteine in water as well as in live cells. 相似文献