Synthesis of Platinum-Containing Conjugated Polymers Bearing Chiral Phosphine Ligands. Study of Geometries and Intermolecular Interactions Leading to Aggregation

Platinum
(Pt)-containing conjugated polymers were synthesized by
the dehydrochlorination coupling polymerization of cis- and trans-dichlorobis­(N-(p-(diphenylphosphino)­benzoyl)-l-valine methyl ester)­platinum­(II)
{cis-PtL2Cl2 and trans-PtL2Cl2, L = P­(Ph)2-p-C6H4CONHCH­[CH­(CH3)2]­CO2CH3} with 1,4-diethynylbenzene, aiming at obtaining polymers
with controlled geometry at the Pt centers. In the polymerization
of cis-PtL2Cl2, the geometry at the Pt centers was controlled by the amine used
in the polymerization and the reaction temperature. The formed polymer
with trans-Pt centers exhibited a circular dichroism
signal at the main chain chromophore region in CH2Cl2/MeOH mixed solvent. Based on the crystal packing state and
non-covalent interaction analysis of a model compound, the chiroptical
activity is attributed to aggregation stabilized by intermolecular
π–π, CH−π, and hydrogen-bonding interactions
between the phosphine ligands.