Clear evidence of the sensitivity of the solvatochromic effect to side chain functionalization in 3‐hexyl‐substituted polythiophenes

Abstract

++The solvatochromic properties of 3-hexyl-substituted polythiophenes functionalized with an ester, ether or hydroxy group at the end of the alkyl side chain are reported. An extraordinarily large shift, AA, = 99 nm, and a dramatic change of the UV/ vis spectral profile are found when the carboxylate is replaced with the hydroxy group by functionalization exchange. The solvatochromic behavior of each polymer is believed to be strictly related to the type of functional group owing to different physical interactions (solvation) between groups different in polarity and solvent molecules. A unique and common chromophoric unit for the final conformation of the 3-hexyl-substituted polythiophenes, induced by the solvatochromic effect, is also suggested. Acta Polymer., 48,251 -255 0 VCH Verlagsgesellschaft mbH, D-69451 Weinheim 1997 0323-7648/97/0102-25 1$10.00+.25/0 25 1

Anomalous Solvatochromic Effect. Comparison Between Decyl and ω-Hydroxydecyl 3-Substituted Polythiophenes

“…This suggests that by reducing the conformational mobility of the polymeric backbone the OH functional group exerts a strong levelling effect on the differences of regioregularity between the three different samples. This corresponds to a similar behavior observed previously [3] for a sample of a non-regioregular poly[3-(6-hydroxyhexyl)-2,5-thienylene] exhibiting a chromism wholly comparable to that of a poly(3-hexyl-2,5-thienylene) completely free of configurational defects.…”

Optical, electrical, and thermochromic properties of polyazothiophene Langmuir–Blodgett films

“…The lines are only to guide the eyes and A (area=2 μm 2 ). The conductivity measured in the dark was 8×10 -10 S/m, which is in agreement with the literature for neutral regio-random polythiophenes [14,36,37]. Under illumination, the conductivity was practically constant up to 75 mW/cm 2 , and then increased to 4×10 -8 S/m at 125 mW/cm 2 , as shown in Fig.…”

Chromic effects in poly(3-(10-hexanoyloxydecyl)-2,5-thienylene) as precursor of ω-hydroxydecyl-functionalized polythiophen

“…Moreover, the ester group, located near the center of the side chain, can randomly bend the direction of the remaining part of the latter, so that the attainment of an ordered structure is more difficult than in alkyl or terminally functionalized side chains. Conversely, the length of the side chain of P2 is very close to the optimum one and, moreover, it has been suggested that the terminal hydroxy group may exert a positive role in controlling an ordered arrangement by hydrogen bonding [4,15]. These considerations can be well explained by the concept of functionalization space [17], defined as the volume in which a given substituent must be introduced in order to preserve an extended effective conjugation length in the resulting polymer.…”