Synthesis of luminescent coordination compounds with bidentate [N,P]-donor ligands containing the iminophosphorane functional group

Abstract

The aim of this thesis is the application of bidentate [N,P]-donor ligands for the preparation of luminescent metal complexes with centres having d10 electronic configuration belonging to the first row of the d-block. The Staudinger reaction between a stoichiometric ratio of bis(diphenylphosphino)methane (dppm) and phenylazide (PhN3) afforded a stable asymmetric iminophosphorane that was employed to coordinate d10 metal centres. The ligand 1-((diphenylphosphaneyl)methyl)-N,1,1-triphenyl-phosphanimine (dppmNPh) shows a greenish fluorescence at the solid state. The reaction of dppmNPh with suitable Cu(I) and Zn(II) precursors allowed to obtain air-sensitive homoleptic and halide complexes. The luminescence of homoleptic complexes is centred in the green region and involves excited states composed by ligands and metals orbitals. The luminescence of Zn(II) derivative is noticeably greater. Cu(I) halide complexes are most likely coordination polymers characterized by greenish luminescence, enhanced by traces of organic solvent. Experimental data suggest that the interaction with the solvent molecules increases the radiative decay rate. Zn(II) halide complexes are poorly soluble in organic solvents. Lifetime measurements on the chloro- and bromo-complexes at room temperature clearly indicate that the emission is a fluorescence from the coordinated ligands, while the presence of iodide in coordination sphere favours a non-radiative decay, probably anticipated by intersystem crossing.