Synthesis, electrochemical, fluorescence and antimicrobial studies of 2-chloro-3-amino-1,4-naphthoquinone bearing mononuclear transition metal dithiocarbamate complexes [M{κ²S,S-S₂C–piperazine–C₂H₄N(H)ClNQ}_n]

Abstract

A novel multifunctional ligand precursor 2-chloro-3-{2-(piperazinyl)ethyl}-amino-1,4-naphthoquinone (L) was synthesized by chemo-selective reaction of 2,3-dichloro-1,4-naphthoquinone and 2-(piperazin-1-yl)ethanamine and characterized, prior to use. A series of mononuclear transition metal dithiocarbamate complexes [M{k 2 S,S-S 2 C-piperazine-C 2 H 4 N(H)ClNQ} n ] {M ¼ Mn(III) 1, Co(III) 2, Ni(II) 3, Cu(II) 4, Zn(II) 5; ClNQ ¼ 2-chloro-1,4-naphthoquinone; n ¼ 3 for 1-2 and n ¼ 2 for 3-5} bearing pendant 2-chloro-3-amino-1,4-naphthoquinone groups were efficiently synthesized through a selfassembly process involving L, CS 2 and corresponding metal acetates. 1-5 were characterized by microanalysis and standard spectroscopic methods such as ESI-MS, IR, 1 H and 13 C NMR and UV-visible absorption spectroscopy. Significantly, all compounds exhibit medium to very strong fluorescence emission bands in the visible region with concomitant Stokes shifts of z280 nm upon excitation at their respective l max values. Thermal stability of complexes 1-5 has been investigated by thermogravimetric analysis. Cyclic voltammetric study clearly reveals that L and 1-5 are electro active with respect to the dominant redox-active naphthoquinone moiety. Further, L and 1-5 were tested against six important pathogen microorganisms viz. S. aureus, B. subtilis, E. coli, P. aeruginosa, C. albicans and A. niger by using the Broth dilution method. A broad spectrum of the strongest antimicrobial activity was determined for the copper(II) complex 4 and L. The enhanced antibacterial activity of L and copper(II) complex 4 against S. aureus apparently reveals them to be a superior antibacterial agent than the reference drug ciprofloxacin.

Derivatives of 4, 4’‐Oxydianiline Show Distinct In Vitro Cytotoxicity, Apoptosis Induction, and Selectivity against HepG2 Cancer Cells

“…Ligand precursor L 3 appeared to be non‐fluorescence, however its complex derivatives 3 a–3 c fluoresces significantly with concomitant Stoke shifting of ∼ 32 nm (Figure S51). The overall fluorescence property of these transition metal dithiocarbamate complexes is consistent with our earlier observations ,,. Magnetic moment values, NMR studies and UV‐visible absorption bands undoubtedly suggest square planar/distorted square planar environment around Ni II / Cu II centers and tetrahedral/distorted tetrahedral environment around Zn II centers in their corresponding complexes, which is further reinforced by DFT calculation performed at B3LYP/LanL2DZ level discussed latter.…”

“…The peaks corresponding to the ligand functionalities in the 1 H NMR spectra of the complexes (Supporting Information) appear very well in the expected range. Distinctly, in the 13 C NMR spectra, all the diamagnetic complexes showed a single distinct downfield resonance at δ 206–207 ppm associated with the N–CS 2 unit ,. (Figure S12, S14, S16, S18, S20, S22).…”

Co(III) N,N′‐diarylformamidine dithiocarbamate complexes: Synthesis, characterization, crystal structures and biological studies

“…Their study showed that the cobalt complex had better antibacterial activity compared to streptomycin (standard) against S. aureus . Verma and Singh also used a multifunctional secondary amine ligand, 2‐chloro‐3{2‐(piperazinyl)ethyl}amino‐1,4‐naphthoquinone, to synthesize mononuclear dithiocarbamate metal complexes and screened them for in vitro antimicrobial activities. Their results showed that all complexes displayed moderate to good antibacterial activities.…”

[N,N-Bis(2-hydroxyethyl)dithiocarbamato-κ2S,S′]bis(triphenylphosphane-κP)copper(I) chloroform monosolvate: crystal structure, Hirshfeld surface analysis and solution NMR measurements

“…The motivation to prepare bis(phosphane)copper(I) dithiocarbamates of general formula (R 3 P) 2 Cu(S 2 CNR 0 R 00 ) (R, R 0 , R 00 = alkyl, aryl) largely stems from the versatile biological properties exhibited by these types of compounds (Skrott & Cvek, 2012;Biersack et al, 2012) and metal dithiocarbamates in general, as summarized in a recent review (Hogarth, 2012). At present, research continues to develop promising antimicrobial agents in light of the growing prevalence of bacterial infections and threats associated with drug-resistant bacteria (Verma & Singh, 2015;Onwudiwe et al, 2016). In our recent efforts to develop anti-microbial agents, phosphanegold(I) dithiocarbamates, R 3 PAu[S 2 CN(iPr)CH 2 CH 2 OH], were prepared and these compounds demonstrated prominent and distinctive anti-microbial activity against a broad range of Gram-positive and Gram-negative bacteria, dependent on the type of P-bound substituent employed (Sim et al, 2014).…”