Control of Higher-Order Structures of Platinum-Containing Conjugated Polymers by Ligand Exchange Reactions: Chirality Transfer from Optically Active Ligands to Optically Inactive Polymers

Abstract

This study reports chirality transfer from optically active diphosphine ligands to optically inactive platinum-containing polymers. Cis-platinum complex 1 smoothly reacted with optically active diphosphine ligands L1 and L2 to give cis-platinum complex 1-L1 and trans dimeric platinum complex 1-L2, respectively. Cyclic trans dimeric complex 1-L2 gradually isomerized to cismonomeric complex 1-L2′. Polymer 4-L2 was insoluble in common organic solvents, even though the reaction was carried out under highly dilute conditions (c = 0.1 mM). On the other hand, polymer 5-L2 was CH 2 Cl 2 -soluble when the reaction was carried out at 1 and 0.1 mM concentrations, in which intramolecular bridging predominated over intermolecular crosslinking. CD spectroscopic measurements suggested that 5-L2 adopts a folded helical conformation, which was supported by DFT calculations.

Synthesis of geometry-controlled platinum-containing polymers bearing optically active bidentate phosphine ligands

“…Poly( 5-6 p ) exhibited a λ max 22 nm longer than that of poly( 5-6 m ), apparently indicating longer conjugation of the para -linkage than that of the meta -counterpart reported in trans -Pt-containing polyphenyleneethynylenes. 22,26…”

“…Poly(5-6p) exhibited a λ max 22 nm longer than that of poly(5-6m), apparently indicating longer conjugation of the para-linkage than that of the meta-counterpart reported in trans-Pt-containing polyphenyleneethynylenes. 22,26 Monomer 5, poly(5-6p) and poly(5-6m) exhibited positive and negative CD signals at 234 and 262 nm, assignable to the chirally fixed benzene rings in the phosphine ligand coordinated to Pt. Poly(5-6p) and poly(5-6m) exhibited no CD signal in the 320-450 nm chromophore region of the main chain.…”

“…On the other hand, it is considered that structurally bent cis -Pt polyynes exhibit optical properties largely different from those of their trans -Pt counterparts. We also synthesized cis -Pt polyynes with diphosphine ligands by a ligand exchange reaction of trans -Pt polyynes with 1,2-bis(diphenylphosphino)ethane 21 and (2 S ,3 S )-bis(diphenylphosphino)butane, 22 as well as P*-chiral diphosphine ligands. 23 The polymers exhibited chiroptical properties based on the chirally twisted main chains, in which the chirality was transferred from the diphosphine ligands.…”

Responsive macrocyclic and supramolecular structures powered by platinum

“…55 Exchange on Pt II acetylide complexes has also been used to make other classes of supramolecular structures, including helicates and linear polymers, enabling dynamic behaviour and reversible structural changes. [56][57][58][59] In principle, this strategy could also be useful to control the size and shape of nano/ micrometre-sized particles while maintaining the intrinsic porosity of the materials.…”

Synthesis of a platinacycle: determination of the structure and examination of the photophysical properties based on DFT calculations

“…12 We have reported a series of Pt-containing polymers and examined their properties, including absorption-emission control by arylene moieties 14 and phosphine ligands, 15 triplet-triplet annihilation upconversion, 16 catalytic activity for hydrosilylation, 17 formation of chirally regulated structures based on chiral amide susbsituents 18,19 and phosphine ligands. [20][21][22] We have synthesized polymers bearing Pt-bipyridine bis(acetylide) complex moieties in the main chain by dehydrochlorination coupling polymerization of Pt-bipyridine dichlorides and bisethynylarylenes. 22 The polymers chirally aggregate in DMF/MeOH mixed solvent, and exhibit liquid crystallinity mainly based on Pt-Ar interaction between the main chains.…”