A Deep Insight into the Photoluminescence Properties of Schiff Base Cd^II and Zn^II Complexes

Abstract

A tridentate N,N,O donor ligand 2,4-dichloro-2-[(2-piperazine-4-yl-ethylimino)-methyl]-phenol (HL) was designed, and eight new Zn and Cd complexes, namely, [Zn(LH)(SCN)] (1), [Zn(LH)(N)] (2), [Zn(LH)(NO)] (3), [Zn(LH)(dca)(OAc)] (4), [Cd(LH)(SCN)] (5), [Cd(LH)(N)] (6), [Cd(LH)(NO)] (7), and [Cd(LH)(dca)(OAc)] (8) [where dca = dicyanamide anion] were synthesized. Five of them (1, 2, 4, 5, 7) were structurally characterized through single-crystal X-ray diffraction analysis. H-Bonding interactions are found to be the major stabilizing factor for crystallization in the solid state. Experimental and computational studies were performed in cooperation to provide a rationalization of the photoluminescence properties of those complexes. The quantum yields are anion-dependent, with enhanced efficiencies in the following order: LH < Cd-SCN(5) < Cd-dca(8) < Cd-N(6) < Cd-NO(7) < Zn-dca(4) < Zn-N(2) < ZnNO(3) < ZnSCN(1). By using quantum chemical calculations we rationalized the above trends. Moreover, the diverse lifetimes observed for those eight complexes were also quantitatively explained by considering the subtle competition between different photo-deactivation pathways.

Schiff-base [4]helicene Zn(ii) complexes as chiral emitters

“…The obtained values are in accordance with previously reported data, and could be explained by the competition between a *- and a CT transition. 40,41 The excitation spectra present a perfect match with the absorption spectra for the four complexes (Fig. 4b and ESI).…”

Tuning the Fluorescence Emission and HOMO‐LUMO Band Gap in Homoleptic Zinc(II) Complexes with N,O‐Bidentate (Imidazo[1,5‐a]pyrid‐3‐yl)phenols

“…Also Schiff base ligands demonstrated to be useful for the synthesis of zinc(II) complexes with remarkable luminescence properties. Very recent examples are fluorescent zinc(II)‐salicylaldiminato compounds, dinuclear zinc salphen macrocycle complexes, and zinc(II) and cadmium(II) complexes with piperazino‐functionalized N , N′,O ‐tridentate ligands …”

The synthesis of a Cu(ii) Schiff base complex using a bidentate N2O2 donor ligand: crystal structure, photophysical properties, and antibacterial activities

“…22,23 Now, efforts have shied towards exploring their application in photonic applications, 24 especially in the eld of luminescent Schiff bases complexes. [25][26][27][28][29] Therefore, as an extension of the research on the structural characterization and properties of Schiff bases complexes with ligands containing O and N atoms, in this contribution, a bidentate N 2 O 2 Schiff base ligand and its Cu(II) complex were synthesized and characterized by single crystal X-ray diffraction, elemental analysis and FTIR spectroscopy. The detailed study of their photophysical properties such as UV-Vis and uorescence were done.…”