New series of MII-dithiocarbamate complexes (M = CuII, NiII and ZnII) holding pendant N,O-Schiff base moieties: Synthesis, characterization, photophysical, crystallographic, anti-microbial and DFT study

•New series of piperazine based monometallic and bimetallic bis-dithiocarbamate complexes holding pendant N,O-Schiff base moieties.•Study of crystal packing patterns revealed the formation of 3D multiple open tubular, 3D herringbone and staircase like supramolecular assembly by L1, 1 and 3, respectively.•Investigation of thermal stability, emission behaviour and antimicrobial properties.•DFT study to rationalise the experimental results.