Structural and Photophysical Properties of 2,1,3-Benzothiadiazole-Based Phosph(III)azane and Its Complexes

Abstract

Here we describe the synthesis of a novel N,N'-bis(2,1,3-benzothiadiazol-4-yl)-1-phenylphosphanediamine (H₂L) and its zinc (II) and copper (I) coordination compounds [Zn₂L₂]·nC₇H₈ (1·nC₇H₈), [Zn₂(H₂L)₂Cl₄]·nC₇H₈ (2·nC₇H₈), and [Cu(H₂L)Cl]_n·nTHF (3·THF). According to single crystal X-ray diffraction analysis, H₂L ligand and its deprotonated species exhibit different coordination modes. An interesting isomerism is observed for the complexes [Zn₂(H₂L)₂Cl₄] (2a and 2b) that differ by the arrangement of H₂L. Both complexes possess internal cavities capable of incorporating toluene molecules. Upon toluene release, the geometry of 2b changes substantially, while that of 2a changes slightly. Due to the diverse structures, the compounds 1-3 reveal different photophysical properties. These results are discussed based on previously reported studies and DFT (density functional theory) calculations.

Keywords: 4-amino-2,1,3-benzothiadiazole; coordination compounds; cyclophosp(III)azane; fluorescence; phosph(III)azane; single crystal X-ray diffraction.