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A novel tellurium (Te) containing fluorophore, 1 and its nickel (2) and copper (3) containing metal organic complex (MOC) have been synthesized to exploit their structural and optical properties and to deploy these molecules as fluorescent probes for the selective and sensitive detection of picric acid (PA) over other commonly available nitro‐explosives. Furthermore, density functional theory (DFT) and single crystal X‐ray diffraction (SCXRD) techniques revealed the inclusion of "soft" Tellurium (Te) and "hard" Nitrogen (N), Oxygen (O) atoms in the molecular frameworks. Owing to the presence of electron rich "N" and "O" atoms along with "Te" in the molecular framework, 1 could efficiently and selectively sense PA with more than 80 % fluorescence quenching efficiency in organic medium and having detection limit of 4.60 μM. The selective detection of PA compared to other nitro‐explosives follows a multi‐mechanism based "turn‐off" sensing which includes photo‐induced electron transfer (PET), electrostatic (π‐π stacking and π‐anion/cation) interaction, intermolecular hydrogen bonding and inner filter effect (IFE). The test strip study also establishes the sensitivity of 1 for detection of PA. [ABSTRACT FROM AUTHOR]

The research article reports the synthesis and structural study of the optimized geometry of selenium (Se) bearing 24- and 28- membered macrocyclic Schiff bases, LaH2, LbH2 and their reactions with zinc metal ion. The reactions of the macrocyclic Schiff bases with ZnCl2 in 1:2 molar ratios result in the formation of bimetallic Zn(II) complexes having molecular composition [Se{(CH2)2N = CPh(4-CH3-C6H2O) PhC = O}2 · Zn2Cl2], (1) and [Se{(CH2)3N = CPh(4-CH3-C6H2O)PhC = O}2 · Zn2Cl2], (2). Moreover, as confirmed by various physico-chemical techniques such as elemental analysis, UV–Vis, FTIR,1H NMR, and mass spectrometry, the proligands underwent partial hydrolytic cleavage at one of the C = N positions and behave like hexadentate (N2O4) ligands binding to two Zn(II) ions via bridging through the Ophenolic atoms, which results in a square pyramidal geometry around Zn(II) with the chlorine atom occupying axial positions. Further, following density functional study, the stable optimized configuration of the Schiff bases LaH2 and LbH2 is found to adopt bowl shape geometry. Conversely, in molecular docking studies, the synthesized complex 1 exhibits a significantly stronger binding affinity (−8.7 kcal/mol) to the spike protein of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) as compared to the common coronavirus disease 2019 (COVID-19) treatment drugs such as chloroquine, hydroxychloroquine, and remdesivir with activity percentage showing more than 20% overall effectiveness than remdesivir and thus indicating its potential for COVID-19 therapeutics. [ABSTRACT FROM AUTHOR]