Here, we report ultraspeed preparation of highly emissive nitrogen‐doped carbon dots (NCDs) using threonine and guanidine hydrochloride by the microwave irradiation method. Experimental conditions such as microwave power, irradiation time, and reactant ratio were varied to achieve high‐quality NCDs. NCDs were thoroughly characterized using transmission electron microscopy, X‐ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, UV–visible spectroscopy, and fluorescence spectroscopy. NCDs presented high aqueous solubility, bright emission with a quantum yield of 30%, and excitation‐dependent emission. Investigation of optical properties unveiled their admirable characters of tolerance to photobleaching, high salinity, pH, and long shelf life. Evaluation of their metal ion detection ability unveiled their selective fluorescence quenching response to Mn (VII), and further explorations revealed the application of NCDs as a label‐free probe for Mn (VII) detection. The probe presented a good linear response (R2 = 0.992) in the concentration range of 5–35 μM with a detection limit of 0.66 μM. Mechanistic studies disclosed that the inner filter effect was responsible for fluorescence quenching. The probe presented no significant interference and was successfully applied for the quantification of Mn (VII) in spiked real‐water samples.

A series of novel 2-arylquinoline-3-fused thiazolo[2,3-c]1,2,4-triazole heterocycles 9a-t were efficiently synthesized using simple conventional methods in good yields. The structure of newly synthesized molecules was characterized on the basis of their IR, 1 H NMR, 13 C NMR and mass spectral data. Among 9at, compounds 9h, 9n, 9b and 9d exhibited highly significant antiproliferative activity against two cancer cell lines C6 (nerve cells) and MCF-7 (human breast adenocarcinoma cells) when compared with standard reference Doxorubicin. In vitro antimicrobial activities of target compounds 9h, 9b, 9d, 9m and 9n were effectuated on Gram-positive Staphylococcus aurus (ATCC 25923), Bacillus subtilis (ATCC 6633) and Gram-negative strains Klebsiella Pneumonia (ATCC 31488) and Escherichia coli (ATCC 25966) strains and found to exhibit promising activity against standard Ciprofloxacin drug. Further, when in vitro antifungal activity was conducted on Aspergillus flavus and Aspergillus niger strains 9h, 9b, 9d and 9n were exhibited potent activity when compared with standard Fluconazole drug moiety.

Synthesis of novel 2‐phenylqinoline conjugated bis‐triazole analogues 8(a–n) demonstrated by a series of reactions concerning Vilsmeier‐Haack reaction, Suzuki‐Miyaura cross coupling, reduction of carbonyl groups, and click reaction. The structure of final compounds predicted based on IR, 1H, 13C NMR and Mass spectral data analysis. The title compounds were screened for their in vitro antimicrobial activities against two‐gram positive (S. aureus and S. pyogens) and two‐gram negative (P. aeruginosa and E. coli) bacteria, and two fungal strains (S. rolfs and F. ricini) by employing Amoxicillin and Bavistin as standard drugs, respectively. The compound containing 3‐chlorophenyl, 4‐(trifluoromethyl)phenyl, 3,4‐dimethylphenyl and 3‐fluoro‐4‐chlorophenyl residues, indicated promising antibacterial activity and the best antifungal activity was reported for compounds containing 3‐chlorophenyl, 4‐methoxyphenyl and 4‐(trifluoromethyl)phenyl residues. Further, Insilco screening of these compounds against COVID‐19 main protease of corona virus had displayed good docking scores and binding interactions in its active site pocket.

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