Synthesis of Platinum-Containing Conjugated Polymers Having QuinoxP* and Bipyridine Ligands. Chirality Transfer from the Phosphine Ligand to the Polymer Backbone

Platinum
(Pt)-containing novel conjugated polymers, poly­(1-2a)–poly­(1-2d) having bipyridine
ligands were synthesized by the Sonogashira–Hagihara
coupling polymerization of [Pt­(4,4′-dibromo-2,2′-bipyridine)­((R,R)-2,3-bis­(tert-butylmethylphosphino)­quinoxaline)­(trifluoromethanesulfonate)2] (1) coordinated with 4,4′-dibromo-2,2′-bipyridine/(R,R)-2,3-bis­(tert-butylmethylphosphino)­quinoxaline
[(R,R)-QuinoxP*] and 1,4-diethynylbenzene
(2a), 1,4-diethynyl-2,5-bis­(heptyloxy)­benzene (2b), 1,4-diethynyl-2,5-bis­(2-ethylhexyloxy)­benzene (2c), and 1,4-diethynyl-2,5-bis­(2-(2-methoxyethoxy)­ethoxy)­benzene
(2d). Poly­(1-2d) exhibited
circular dichroism signals derived from (R,R)-QuinoxP* and the conjugated main chain around 290 and
440 nm in DMF, respectively. The simulated CD spectroscopic pattern
of a low molecular model compound, M1-Pt, agreed well with the observed spectra. The TEM images of poly­(1-2d) in the solid state exhibited dispersed
patterns with sizes around 10 nm. Concentrated solutions of polymer 1-2d in DMF and CHCl3 partly exhibited patterns
assignable to the formation of lyotropic liquid crystals.