Structural characterisation of a series of acetylide-functionalised oligopyridines and the synthesis, characterisation and optical spectroscopy of platinum di-ynes and poly-ynes containing oligopyridyl linker groups in the backbone

摘要

A series of trimethylsilyl-protected bis(ethynyl)oligopyridine Me_3SiC ident to C-R-C ident to C-SiMe, (R = 2,2'-bipyridine-5,5'-diyl (1a), 2,2'-bipyridine-6,6'-diyl (2a), 2,2':6',2"-terpyridine-6,6"-diyl (3a), 4'-phenyl-2,2':6',2"-terpyridine-6,6"-diyl (4a)) has been synthesised and 2a-4a have been characterised by single crystal X-ray crystallography. The corresponding terminal di-ynes H-C ident to C-R-C ident to CH (1b-4b) and their dinuclear platinum(II) complexes trans-[(Et_3P)_2(Ph)Pt-C ident to C-R-C ident to C-Pt(Ph)(Et_3P)_2] (1M-4M) have been characterised spectroscopically and by single-crystal X-ray crystallography for 2M. Novel platinum(II) poly-yne polymers trans-[Pt(PBu_3~N)_2-C ident to C-R-C ident to C-]_n (1P-4P) containing the oligopyridyl linker groups in the bakbone have been synthesised by the CuI-catalysed dehydrohalogenation polyondensation reaction of 1b-4b and trans-[(Bu_3P)_2PtCl_2] in Pr_2~iNH-CH_2Cl_2. The polymeric materials exhibit decreasing thermal stability with increasing number of pyridine units in the linker group. In the absorption and phosphorescence spectra, the platinum(II) poly-yne an di-yne complexes 1P, 1M show red shifts whereas the complexes 2P-3P, 2M-3M show blue shifts of the S_1 and T_1 states. At room temperature, the phosphoresence spectra indicate some excimer formation whereas at 10 K, only intra-chain emission occurs. The results of the photophysical studies are compared with those obtained for other platinum(II)-containing poly-yns and related organometallic polymers.