Synthesis, characterization and electrochemiluminescent properties of cyclometalated platinum(II) complexes with substituted 2-phenylpyridine ligands

• Published in: Dalton transactions : an international journal of inorganic chemistry 2013-03, Vol.42 (11), p.4059-4067
• Main Authors: Li, Chunxiang, Wang, Shuqin, Huang, Yangmei, Zheng, Bin, Tian, Ziqi, Wen, Yonghong, Li, Feng
• Format: Article
• Language: English
• Subjects: Acetylacetone; Chemiluminescence; Coordination Complexes - chemical synthesis; Coordination Complexes - chemistry; Crystallography, X-Ray; Electrochemistry; Excitation spectra; Lead (metal); Ligands; Luminescence; Magnetic Resonance Spectroscopy; Mass Spectrometry; Models, Molecular; Molecular Dynamics Simulation; NMR spectroscopy; Organoplatinum Compounds - chemical synthesis; Organoplatinum Compounds - chemistry; Pyridines - chemical synthesis; Pyridines - chemistry; Solvents; Spectra
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c2dt32466k

Two neutral cyclometalated platinum(II) complexes, Pt(DPP)(acac) and Pt(BPP)(acac) (DPP = 2,4-diphenylpyridine, BPP = 2-(4-tert-butylphenyl)-4-phenylpyridine, acac = acetylacetone), have been synthesized and characterized by (1)H NMR spectroscopy, mass spectrometry, elemental analyses and by X-ray crystallography for Pt(DPP)(acac). Electrogenerated chemiluminescence (ECL) of the two complexes in the absence or presence of coreactant tri-n-propylamine (TPrA) in different solvents (CH(3)CN, CH(2)Cl(2), DMF, CH(3)CN/H(2)O (V, 50 : 50)) has been studied. The ECL spectra are identical to their own PL spectra, indicating that ECL processes lead to the same metal-to-ligand charge-transfer ((3)MLCT) excited state that is generated by light excitation. The ECL potentials of Pt(DPP)(acac) and Pt(BPP)(acac)/TPrA in CH(3)CN and CH(3)CN/H(2)O solution were at ~0.75 V vs. SCE, and significantly negatively shifted by about 0.6 V compared to that of the Ru(bpy)(3)(2+)/TPrA system. The ECL quantum efficiencies of the complexes are comparable to that of the Ru(bpy)(3)(2+)/TPrA system. The significant increase of the ECL signal in the coreactant system is due to the formation of the strongly reducing intermediate TPrA˙. It is noteworthy that the ECL efficiencies of the synthesized compounds are much higher than that of the tridentate polypyridyl ligands.