Synthesis, optical absorption, fluorescence, quantum efficiency, and electrical conductivity studies of pyridine pyridinium dialkynyl organic and Pt(II)-sigma-acetylide monomers and polymers

Synthesis of a variety of 2,5- and 2,6-diethynylpyridine based organic and Pt-II-sigma-acetylide monomers and polymers is reported. Quaternization of pyridine nitrogen via solution nucleophilic substitution reactions with methyl iodide and methyl triflate yields stable pyridinium analogs and is accompanied by strong red shifts in the UV-vis absorption spectra. The latter is indicative of enhanced cc-electron delocalization along the backbone upon quaternization. These compounds exhibit strong fluorescence with quantum yields of 0.015-0.058 for the monomers and 0.060-0.223 for the polymers. Quaternization leads to enhanced fluorescence intensities and quantum efficiencies. These polymers are insulators in the ground state, however, and, upon doping with iodine, they exhibit semiconducting behavior.