Synthesis, characterization and electrochemiluminescent properties of cyclometalated platinum(ii) complexes with substituted 2-phenylpyridine ligandsCCDC reference number 901672. For crystallographic data in CIF or other electronic format see DOI: 10.1039/c2dt32466k

• Main Authors: Li, Chunxiang, Wang, Shuqin, Huang, Yangmei, Zheng, Bin, Tian, Ziqi, Wen, Yonghong, Li, Feng
• Format: Article
• Language: English
• 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&z.rad;. It is noteworthy that the ECL efficiencies of the synthesized compounds are much higher than that of the tridentate polypyridyl ligands. Two new neutral cyclometalated platinum( ii ) complexes with substituted 2-phenylpyridine have been synthesized and characterized. The ECL of the two complexes has been studied and the possible pathway was proposed.