Synthesis, crystal structure, photophysical property and electropolymerization of Pt(II) complexes with carbazole-grafting 2-(2-pyridyl)benzimidazole

• Published in: Inorganic chemistry communications 2011-09, Vol.14 (9), p.1520-1524
• Main Authors: Qiu, Dongfang, Guo, Yingchen, Wang, Hongwei, Bao, Xiaoyu, Feng, Yuquan, Huang, Qunzeng, Zeng, Junliang, Qiu, Guozeng
• Format: Article
• Language: English
• Subjects: 2-(2-pyridyl)benzimidazole; Carbazole; Crystal structure; Electropolymerization; Photophysics; Pt(II) complex
• ISSN: 1387-7003; 1879-0259
• DOI: 10.1016/j.inoche.2011.06.012

Two neutral-charged Pt(II) complexes, i.e., [(PBC)PtCl 2] ( 5) and [(PBC)Pt(C ≡ CC 6H 5) 2] ( 6) (PBC = N-[4-(9-carbazole)butyl]-2-(2-pyridyl)benzimidazole) have been synthesized and verified by 1H NMR and X-ray crystallography. In each of them, the coordinate geometry of Pt atom is a distorted square planar configuration with bond distances and angles in the normal range. Complex 6 shows an intense metal-to-ligand charge transfer ( 1MLCT) ( dπ(Pt) → π*(L)) transition at 412 nm in the UV-Vis absorption spectrum and a strong phosphorescence at 593 nm in CH 2Cl 2 solution at ambient temperature. By selective optical-stimulation at 320 nm, an incomplete intramolecular energy transfer process from the carbazole unit to the [(PB)Pt(C ≡ CC 6H 5) 2] center results in unbalanced dual-emissive bands of a quenched carbazole-based luminescence in deep blue region and an orange 3MLCT emission with increasing intensity. The introduction of carbazole unit also triggers the electropolymerization of ligand PBC and complexes 5 and 6. The as-formed polymer film from complex 5 has good conductivity, stability and clear anodic coloration effect. Functionalized Pt(II) complexes: The neutral-charged Pt(II) arylacetylide and chloride complexes with N-[4-(9-carbazole)butyl]-2-(2-pyridyl)benzimidazole (PBC) show an enhanced orange 3MLCT emission induced by an intramolecular energy transfer process and the promising electropolymerization activity to form an anodic coloration film, respectively. [Display omitted] ► Carbazole unit as the high triplet energy donor. ► Bi-chromophoric system with an intramolecular energy transfer process. ► Carbazole unit as the electro-active moiety. ► Conductive metallopolymer film with a clearly electrochromic behaviour.