Chiroptical properties of a chiral-substituted poly(thienylene vinylene)

Abstract

Poly(3,4‐bis[(S)‐2‐methylbutoxy]‐2,5‐thienylene vinylene) (BMB‐PTV), the first example of a PTV derivative with optically active side chains, was prepared using a TiCl4/Zn‐induced coupling of the monomeric dialdehyde. The linear absorption spectra of BMB‐PTV exhibit a strong solvatochromic effect: λmax=601 nm in a good solvent and λmax=570 nm in a poor solvent. In good solvents the polymer chains contain a high degree of intrachain order, while optical activity associated with the π‐π* transition is absent. In contrast, the solvatochromic shift observed in poor solvents is accompanied by the emergence of a strong activity in circular dichroism spectroscopy, attributed to the formation of chiral superstructures of multiple chains. Chiral superstructures or microaggregates are also present in the solid state (spin‐coated films) and their concentration can be altered by annealing.

Cis /Cis -2,5-dipropenylthiophene monomers for high-molecular-weight poly(2,5-thienylene vinylene)s through acyclic diene metathesis polymerization

“…The scattering signal at approximately 23.8° is tentatively assigned to π–π stacking ( d π – π = 3.7 Å) and is only observed in the powder scattering profile, indicating edge‐on packing of polymer chains and possible shorter‐ranged ordering in thin films, which is consistent with previous reports . (h,j), (f)…”

“…(A,B)] match closely with those of regio‐random P3DTVs obtained from Stille coupling reactions but are significantly broader than those of regio‐regular P3DTVs prepared from Wittig type condensation reactions . (h), (f) Regio‐irregularity is expected in ADMET polymerization of cis −3DTV as propenyl groups at both 2‐ and 5‐positions of the monomer can cross‐metathesize with each other. Signals due to propenyl and aldehyde (b,d) end‐groups could not be observed in the 1 H NMR spectrum (Fig.…”

“…PTVs possess high crystallinity, broad absorption spectra, and high charge mobility and have found applications in FETs, nonlinear optics, and OPVs . A variety of synthetic methods have been developed over the years for PTV preparation, including earlier examples involving Gilch‐type reactions and elimination from soluble precursor polymers, McMurry coupling, and Wittig‐type reactions of aldehyde‐containing monomers, transition metal catalyzed coupling reactions, and more recently, ADMET polymerization of thiophene monomers bearing double bonds at 2,5‐positions . In these existing examples of ADMET synthesis of PTVs, dipropenylthiophene monomers were exclusively applied instead of the more reactive divinylthiophene analogs, (a) as the later are far more susceptible to free‐radical‐induced polymerization and side‐reactions .…”

Designed synthesis and chiroptical properties of regioregular poly(p-phenyleneethynylene-alter-m-phenyleneethynylene) bearing (−)-trans-myrtanoxyl side groups

“…5(b)), the spectra are almost identical in the range at longer wavelength ( > 375 nm), but the relative intensities of the bands in the range at shorter wavelength ( < 375 nm) slightly increase with increasing annealing temperature, and similar to the chiral polythiophylenevinylene (BMB-PTV) reported by Cronelissen et al [18], the maximum absorptions are slightly blue-shifted. The normalized emission spectra of Myr-PMPE-1 film before and after annealing are shown in Fig.…”

“…(2) Conjugated polymers with chiral side groups, including polythiophenes [6,[15][16][17][18], poly(p-phenylenevinylene)s [7,19,20], polyfluorenes [21][22][23], polyacetylenes [24,25], polysilylenes [26][27][28] and polycarbazoles [29] etc.…”