Two water-soluble near-infrared luminescent probes, which possess both conventional intense Stokes fluorescence and unique single-photon frequency upconversion luminescence (FUCL), were developed for sensitive and selective detection of pH changes in live cells. The water solubility and biocompatibility of these probes were achieved by introducing mannose residues through 2,2′-(ethylenedioxy)diethylamine tethered spacers to a near-infrared conventional fluorescence (CF) and FUCL organic fluorophore. At a pH higher than 7.4, the probes have ring-closed spirocyclic lactam structures, thus are colorless and nonfluorescent. Nevertheless, they sensitively respond to acidic pH values, with a drastic structural change to ring-opened spirocyclic lactam forms, which cause significant absorbance increases at 714 nm. Correspondingly, their near-infrared CF and FUCL intensities at 740 nm are also significantly enhanced when excited by 690 and 808 nm, respectively. The probes hold a variety of advantages such as high sensitivity, excellent reversibility and selectivity to pH over metal ions, low cellular autofluorescence background interference, good cell membrane permeability and photostability, as well as low cytotoxicity. Our results have successfully proven that these probes can visualize intracellular lysosomal pH changes in live cells by monitoring both near-infrared CF and FUCL changes.

N-heterocyclic carbene (NHC) organocatalysis is widely employed for the umpolung of aldehydes and recently to the umpolung of Michael acceptors and aldimines. Described herein is the NHC-organocatalyzed umpolung of aldimines for the enantioselective synthesis of nitrogen heterocycles. The bisimines generated from the condensation of 1,2-phenylenediamines and salicylaldehydes undergo intramolecular cyclization in the presence of a chiral NHC catalyst, resulting in the formation of dihydroquinoxalines in moderate to good yields and er values. Detailed DFT studies shed light on the role of −OH groups in stabilizing the initially generated aza-Breslow intermediates via intramolecular hydrogen bonds. Preliminary photophysical studies on the synthesized dihydroquinoxalines revealed that these molecules can be used for the sensing of various acids and bases.

Computational exploration of hydrogen storage efficiency of multiple metal ion (Li+/Mg2+)-decorated PAHs.

Efficient detection of arsenate (AsO43-) from contaminated drinking water extracted from underground becomes a matter of utmost necessity as well as exquisite challenge owing to on growing public health damage...

Exploring a covalent organic framework (COF) material as an efficient metal-free photocatalyst and as an adsorbent for the removal of pollutants from contaminated water is very challenging in the context of sustainable chemistry. Herein, we report a new porous crystalline COF, C6-TRZ-TPA COF, via segregation of donor–acceptor moieties through the extended Schiff base condensation between tris(4-formylphenyl)amine and 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)trianiline. This COF displayed a Brunauer–Emmett–Teller (BET) surface area of 1058 m2 g–1 with a pore volume of 0.73 cc g–1. Again, extended π-conjugation, the presence of heteroatoms throughout the framework, and a narrow band gap of 2.2 eV, all these features collectively work for the environmental remediation in two different perspectives: it could harness solar energy for environmental clean-up, where the COF has been explored as a robust metal-free photocatalyst for wastewater treatment and as an adsorbent for iodine capture. In our endeavor of wastewater treatment, we have conducted the photodegradation of rose bengal (RB) and methylene blue (MB) as model pollutants since these are extremely toxic, are health hazard, and bioaccumulative in nature. The catalyst C6-TRZ-TPA COF showed a very high catalytic efficiency of 99% towards the degradation of 250 parts per million (ppm) of RB solution in 80 min under visible light irradiation with the rate constant of 0.05 min–1. Further, C6-TRZ-TPA COF is found to be an excellent adsorbent as it efficiently adsorbed radioactive iodine from its solution as well as from the vapor phase. The material exhibits a very rapid iodine capturing tendency with an outstanding iodine vapor uptake capacity of 4832 mg g–1.

We report herein the development of a new pyridine-pyrazole based bis-bidentate asymmetric chemosensor that shows excellent turn-on chelation-enhanced Al3+-responsive fluorescence.

The detoxication of DMMP (dimethyl methylphosphonate) mediated by molecular TiO has been investigated computationally using density functional theory (DFT). From our previous studies, it is evident that the unimolecular detoxication of OPCs (organophosphorus compounds) is kinetically unfeasible at room temperature due to the significantly high activation barrier. Thus, the aim of our work is to find out whether molecular TiO can make any significant impact on the kinetic feasibility of the detoxication processes or not. Here, we have identified a total of three detoxication pathways, where in the first step the detoxication occurs through H-abstraction with the assistance of TiO, and in the second step, the titanium complex is separated from the respective phospho-titanium complexes. The outcomes reveal that the TiO-mediated detoxication pathways are at least 20.0 kcal/mol more favorable than their respective unimolecular pathways and that among them, the α-H-mediated isomerization is found to be the most feasible pathway. When the separation of a titanium complex is under consideration, the double HO-assisted mechanism is found to be the favored pathway. Overall, the entire work provides a widespread idea about the efficiency of molecular TiO-assisted detoxication of DMMP, which can be well applicable to other OPCs also.

The impetus for the present work was to design multifunctional inorganic materials that can be utilized in their original assynthesized state of the matter. Accordingly, we have successfully designed a benzene-tricarboxylic acid based dual-purpose Fe-metallogel that can be used as an efficient material for cryogenic magnetic cooling as well as electronic device fabrication as Schottky barrier diode in their original gel state. The metallogel shows remarkable mechanical strength, selfsustainability and thixotropic behaviour. The gel sample has been thoroughly characterized using IR, UV-Vis spectroscopy, SEM, TEM, AFM techniques, XPS and Mössbauer spectroscopy. The porous nature, which forms the basis of the current gel based MCE study and SBD fabrication, was confirmed with gas sorption data. The porous metallogel network with by-default entrapped anion and protic solvents of the fabricated electrical device provides an excellent platform for charge transportation with a corroborating conductivity value of 4.53 × 10 À 6 Sm À 1 . As if to complement the notion of multifunctional material, the magnetic studies on the Fe-gel show significant cryogenic magnetic cooling behaviour. The theoretical result calculated using DFT are found to be highly consistent with the experimental results of the metallogel. Furthermore, we have evaluated the potential of the compound as a fuel cell membrane with detailed proton conductivity measurements on the xerogel, showing an encouraging value of 4.58 × 10 À 4 S/ cmat 95 % relative humidity and 75 °C temperature.