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(E)-N-(diaminomethylene)-4-(3,5-dichloro-2-hydroxybenzylideneamino)benzene (HL), a sulfaguanidine (SGN) appended Schiff base, acts as fluorescent ‘turn-on’ Zn2+ sensor in aqueous medium and limit of detection (LOD) is 37.13 nM which is much lower than the WHO recommended value (76 µM) in the drinking water. The composition of the complex has been supported by Job’s plot and mass spectral analysis. HL is weakly emissive which may be due to excited state induced proton transfer; however, binding with Zn2+ may stop this quenching and induce the chelation enhancement of fluorescence (CHEF) at 514 nm in presence of large number of biologically important cations. The complex shows much higher antibacterial efficiency than HL and sulfaguanidine (SGN) (MIC of SGN, >1000 μg/ml; HL, >1000 μg/ml and that of [ZnL2(H2O)] is 64 μg/ml for Escherichia coli). In living cells (African Monkey Vero Cells) the trace quantity of Zn2+ has been detected using the probe (HL). MTT assay confirms that the probe is non-toxic upto 200 μg/ml (774 µM). Both Density Functional Theory and molecular docking (PDB id, 5EVA) computation have been used to explain the electronic properties and to forecast the interaction of metal–ligand complex with target protein β-lactamase in bacterial cells.

The present work embodies outward oxygen atom transfer (OAT) reaction from pyridylbenzoxazole (L1) chelated oxorhenium(V) complex of type [ReOCl3(L1)], 1 towards oxophilic PMe2Ph resulting in the formation of reduced Re(III) derivative [Re(OPMe2Ph)Cl3(L1)], 4 containing oxidised phosphine trans to azole nitrogen. Another possible isomer (4a) having oxidised phosphine trans to pyridyl nitrogen has not been isolated. Structural elucidation of 4 reveals meridional disposition of three Cl atoms around the metal featuring distorted octahedral geometry. DFT analysis of isomers of type [Re(OPMe2Ph)Cl3(L1)] (4 and 4a) confirms isoenergetic nature in gas phase, however, stereospecific binding of L1 to Re(III) centre affording 4 as exclusive product is attributed to crystal packing force. 1 → 4 redox transformation has also been attended with the change in singlet → triplet spin state of the metal. Triplet state of 4 is more stable by ca. 15 kcal mol−1 compared to the singlet state in gas phase. Two electron paramagnetic nature (2.13 μB) in solid state affirms triplet ground state characterised with strong orbital coupling. Kinetic data for 1 → 4 transformation suggests associative pathway (ΔS≠ = ∼−36 J/K/mol) with no major structural reorganisation in the primary coordination sphere of the substrate and the reagent (ΔH≠ = ∼+10 kcal mol−1) to reach the transition state. Pyridylbenzthiazole (L2) chelated oxorhenium(V) complex of type [ReOCl3(L2)], 1b also reacts with PMe2Ph in a same manner to from [Re(OPMe2Ph)Cl3(L2)], 4b where the pyridyl nitrogen lies trans to phosphineoxide moiety unlike 4. The second order rate constants of OAT to PMe2Ph for [ReOCl3(L1)] are nearly two times higher than that of [ReOCl3(L2)] at all recorded temperatures due to difference in azole heteroatom electronegativity, ReV O bond length and ReVI/ReV reduction potential.

[Rh(α-NaiR)2Cl2]ClO4 (2) (α-NaiR (1), 1-alkyl-2-(naphthyl-α-azo)imidazoles, R = Me (a), Et (b)) complexes react with ArNH2 (where Ar = X C6H4 , X = H (3), Me (4), Cl (5)) to synthesize the naphthyl appended C N fused bis-[1-alkyl-2-{(7-imidoaryl)naphthyl-α-azo}imidazole-N,N′,N″]rhodium(III)perchlorate complexes [Rh(α-NaiR N Ar)2]ClO4 (3–5). The single crystal X-ray diffraction measurements of one of the complexes, [Rh(α-NaiEt N C6H5)2]ClO4 (3b), confirms the structure. The absorption spectra of the complexes 3–5 show high intense broad multiple transitions at 650–800 nm compared to the transition of the precursor 2 at 500 nm and DFT computations have assigned this transition to an admixture of LLCT (ligand-to-ligand charge transfer, imidoaryl → azonaphthyl) and LMCT transitions. The cyclic voltammogram shows a quasireversible oxidation at >0.8 V, which is assigned by DFT computation to oxidation of the imidoaryl chelate, along with azo reductions at

WOS: 000441856400001, 1-Alkyl-2-(arylazo)imidazoles (Haai-C4H9 (1), Haai-C10H21 (2)) and their Pt(II) complexes, [Pt(Haai-C4H9)Cl-2] (3) and [Pt(Haai-C10H21)Cl-2] (4) were synthesized and characterized by different spectroscopic studies and structural confirmation has been achieved in the case of complex 3 by single crystal X-ray diffraction analysis. Complexes 3 and 4 were evaluated for their in vitro anti-mycobacterial activity against Mycobacterium tuberculosis H37Ra (ATCC 25177) and H(37)Rv (ATCC 25618) strains, as well as against two clinical strains. Their cytotoxic effects on three cancer cell lines, A549 (human lung carcinoma), MCF-7 (human breast cancer) and Caco-2 (colorectal adenocarcinoma line), and one normal cell line, 3T3 (mouse normal fibroblast) were examined. The DNA interaction of the complexes shows that the intrinsic binding constant (K-b) decreases with the increasing molecular dimension and the chain length of the 1-alkyl group. The longer 1-alkyl chain substituted complex, [Pt(Haai-C10H21)Cl-2] (4), is less efficient due to hydrophobic interactions than the lower homologue [Pt(Haai-C4H9)Cl-2] (3) (K-b(3), 5.9(2) x 10(6) M-1 and molar volume, 276.03(10) cm(3) mol(-1); [Pt(Haai-C10H21)Cl-2], K-b(4), 5.86(2) x 10(5) M-1 and molar volume, 397.56(8) cm(3) mol(-1)), University Grants Commission, New Delhi, India [F./PDFSS-2015-17-WES-12882]; Council of Scientific and Industrial Research (CSIR), New Delhi, India [01(2731)/13/EMR-II], Financial support from the University Grants Commission (No. F./PDFSS-2015-17-WES-12882) New Delhi, India and the Council of Scientific and Industrial Research (CSIR, Sanction No. 01(2731)/13/EMR-II,), New Delhi, India are gratefully acknowledged.

[(SMX-N C-C6H2(o,p-Cl2)-O)]2Cu (1) and [(STZ-N C-C6H2(o,p-Cl2)-O)]2Cu (2) (SMX: Sulfamethoxazole; STZ: Sulfathiazole) have been characterized by spectroscopic data and the structural confirmation of 2 has been carried out by single crystal X-ray diffraction studies. The structure shows distorted square pyramid geometry and ligand serves as N, O chelator and OH2 occupies the axial position. Packing shows hydrogen bonded 1D chain and π—π interaction generates 2D supramolecular structure. Anticancer activity of the complexes against human breast cancer cell (MDA-MB 231) lines shows considerably low IC50, 82 μM (1) and 53 μM (2). DNA interaction of the complexes, 1 and 2, determines the binding constants 1.515 × 105 M−1 (1) and 1.164 × 105 M−1 (2). Docking studies have been performed with the DNA structure (PDB id 1ZEW ) to establish drug activity by groove binding.