N,N'-bis(3-dithiocarbamatopropyl) piperazine bridged metallomacrocyclic complexes of Ni(II), Cu(II) and Zn(II): Synthesis, characterization, photophysical, in-silico study and their potential utility in heavy metal ion sensing.

[Display omitted] • New series of metallomacrocyclic complexes holding functionalized linkers. • Ability to act as single source precursors for the synthesis of MS nanoparticle. • HOMO-LUMO band gaps falls in the range of 1.19–1.33 eV for some of the complexes. • Potential molecular probes for optical detection of Pb(II), Cd(II) and Hg(II) ions. Two secondary diamines viz. N,N' -bis{3-(p -methoxybenzylamino)propyl}piperazine (H 2 L1) and N,N' -bis{3-(p-chlorobenzylamino)propyl}piperazine (H 2 L2) holding N,N' -bispropylpiperazine linkers have been prepared and subsequently used to derive a new series of N,N' -bis(3-dithiocarbamatopropyl) piperazine bridged metallomacrocyclic complexes [M(II) 2 - µ2 -bis-{(κ2S,S -S 2 CN(R)C 3 H 6) 2 piperazine}] wherein R = p -methoxybenzyl, M = Ni(II) 1, Cu(II) 2, Zn(II) 3; R = p -chlorobenzyl, M = Ni(II) 4, Cu(II) 5, Zn(II) 6. The formation and purity of all the metallomacrocyclic dithiocarbamate complexes were verified by microanalysis and standard methods such as HRMS, NMR, IR and UV–Visible absorption spectroscopy and corroborated by density functional theory calculations. The experimental (magnetic susceptibility and UV–Visible) and theoretical calculations suggest a square planar/distorted square planar environment around nickel(II)/copper(II) and tetrahedral/distorted tetrahedral environment around zinc(II) centres in 1–6. Thermogravimetric study was carried out on 1–6 to study their thermal stability and degradation behaviour. Notably, TG curves of compounds 2, 3 and 5 gave a stable residual mass corresponding to corresponding metal sulphides (MS). Notably, the calculated HOMO-LUMO gaps (1.19–1.33 eV) for Cu(II)-dithiocarbamate 2 and 5 indicates their semiconducting nature. The potentials of these metallomacrocycles as a molecular probe for optical sensing of environmentally hazardous heavy metal ions ca Pb(II), Cd(II) and Hg(II) were further examined by using UV–Visible and fluorescence spectroscopies. [ABSTRACT FROM AUTHOR]