Enantioselective approach towards the synthesis of spiro-indeno [1,2-b] quinoxaline pyrrolothiazoles as antioxidant and antiproliferative

The 1,3-dipolar cycloaddition reactions of azomethine ylide generated in situ from indeno quinoxaline and thiazolidine-2-carboxylic acid to a series of quinoline bearing dipolarophile afforded novel spiro indeno-quinoxaline pyrrolo thiazoles in quantitative yields. The newly synthesized compounds were characterized using different spectroscopic techniques. Furthermore, the molecular structure of compound 5c was confirmed by single crystal X-ray crystallography. The synthesized compounds were screened for their in vitro antioxidant activity and in vitro cytotoxic activity against breast cancer cell line MCF-7 and adenocarcinomic cancer cell line A-549. Compound containing more electron donors in quinoline site were found to be more potent with good IC₅₀ values.     

S,N‐GQDs Enzyme Mimicked Electrochemical Sensor to Detect the Hazardous Level of Monocrotophos in Water

The detection of monocrotophos, an organophosphate pesticide, which disrupts water bodies and the entire eco‐system has been proposed. The non‐enzymatic organophosphate electrochemical biosensor has been developed with sulphur, nitrogen co‐doped graphene quantum dots (S,N‐GQDSs) nanocatalyst as an interface that mimics the enzyme to activate acetylthiocholine chloride (ATChCl) with significant sensitivity and selectivity. Activation of ATChCl in the absence of enzyme using the S,N‐GQDs interface is the maiden approach accomplished in this work. Activated ATChCl was employed to detect and quantify monocrotophos by reducing phosphoric acid to phosphorous acid during incubation and further to elemental phosphorous. The sensor detects the separation of phosphorus at ?131 mV (vs Ag/AgCl) by non‐enzymatic approach coupled with amperometric analysis. The sensor exhibited a limit of detection and a limit of quantification (LOQ) of 25 and 83 nM L^?1 respectively.     

A Tailored Heptazine-Based Porous Polymeric Network as a Versatile Heterogeneous (Photo)catalyst

A heptazine-based microporous polymeric network, HMP-TAPA was synthesised by direct coupling of trichloroheptazine and tris(4-aminophenyl)amine (TAPA). A high surface area of 424 m²/g was achieved, which is the highest surface area among heptazine-based polymeric networks (HMPs). The tailored electron-donor and -acceptor units in HMP-TAPA give broad visible-light absorption. HMP-TAPA was employed as metal-free photocatalyst for oxidative coupling of amines to imines under visible light irradiation with 98 % selectivity. Furthermore, the surface basicity of HMP-TAPA was used to achieve metal-free heterogeneous base catalysis for Knoevenagel condensation under base-free conditions with >99 % conversion. In addition, HMP-TAPA showed extreme robustness over a wide pH range (1–14). The versatility and flexibility of the current material design is beneficial for understanding its photoactivity and surface basicity so as to design dual active (photo)catalyst materials for specific applications.     

L-Proline catalyzed three component synthesis of pyrano[2,3-c]pyrazole-5-carbonitrile derivatives and in vitro antimalarial evaluation

An efficient one-pot synthesis of 6-amino-4-(2-chloroquinolin-3-yl)-3-methyl-2, 4-dihydro-pyrano[2,3-c]pyrazole-5-carbonitrile derivatives (4a–f)(5a–f) by three component reactions of 2-chloroquinolin-3-carbaldehyde derivatives, malanonitrile, and 3-methyl pyrazolin-5-one derivatives catalyzed by L-proline in ethanol medium under mild conditions is established. The synthesized compounds were evaluated for antimalarial activity and the LC₅₀/LC₉₀ values were described. Compounds 4d, 5d, and 5f exhibits good antimalarial activity when compared to other pyrano[2,3-c]pyrazole scaffolds.     

Room Temperature Synthesis of Heptazine‐Based Microporous Polymer Networks as Photocatalysts for Hydrogen Evolution

Two emerging material classes are combined in this work, namely polymeric carbon nitrides and microporous polymer networks. The former, polymeric carbon nitrides, are composed of amine‐bridged heptazine moieties and showed interesting performance as a metal‐free photocatalyst. These materials have, however, to be prepared at high temperatures, making control of their chemical structure difficult. The latter, microporous polymer networks have received increasing interest due to their high surface area, giving rise to interesting applications in gas storage or catalysis. Here, the central building block of carbon nitrides, a functionalized heptazine as monomer, and tecton are used to create microporous polymer networks. The resulting heptazine‐based microporous polymers show high porosity, while their chemical structure resembles the ones of carbon nitrides. The polymers show activity for the photocatalytic production of hydrogen from water, even under visible light illumination.