Synthesis, spectroscopic characterization and crystal structure of novel NNNN-donor μ-bis(bidentate) tetraaza acyclic Schiff base ligands

Novel NNNN-donor μ-bis(bidentate) tetraaza acyclic Schiff base ligands with different substituents (CF3, N(CH3)2 or OH groups) were synthesized by the condensation reaction of triethylenetetramine with 4-substituted benzaldehydes. Triethylenetetramine tris(4-trifluoromethylbenzylidene) (TTFMB), triethylenetetramine tris(4-dimethylaminobenzylidene) (TTDMB) and triethylenetetramine tris(2,4-dihydroxybenzylidene) (TTDHB) were formed as N4 donor ligands. The formation of a five-membered imidazolidine ring from the ethylenediamine backbone as a spacer-cumbridging unit gives rise to a new type of imidazolidine ligand. The structure of the TTFMB and TTDMB were determined by single crystal X-ray crystallography. The synthesized ligands have been characterized on the basis of the results of cyclic voltammetry (CV) and spectroscopic studies viz. FT-IR spectroscopy (FT-IR), mass spectroscopy (MS) and UV–Vis spectroscopy (UV–Vis).

Graphical abstractThree new tetraaza N4 acyclic Schiff bases with three pendant arms are prepared. The X-ray structure (TTFMB and TTDMB), UV–Vis, CV, FT-IR and MS of the Schiff bases have been determined.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Three new tetraaza acyclic Schiff bases were prepared. ► Spectroscopic characterization and crystal structure were determined. ► Five-membered ring spacer as a novel type of imidazolidine ligand is formed. ► A novel spacer-cumbridging unit is formed.