Synthesis and characterization of poly(fluorene vinylene) copolymers containing thienylene–vinylene units

Abstract

Narrow-band-gap 2,5-thienylene-divinylene (ThV) units were incorporated into the poly(fluorene vinylene) backbone via a Gilch reaction as an energy trap with various feed ratios; this yielded pronounced changes in the electrochemical and optical properties of the material. The energy levels of the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the polymers {poly(9,9-di-iso-octylfluorene vinylene) [poly(fluorene vinylene-co-thiophene vinylene (FV))], C1, and C2} were estimated to be 25.53 to 25.10 eV and 22.98 to 22.84 eV, respectively, by cyclic voltammetry measurements. In comparison with poly(FV), the HOMO energy levels of polymers poly(fluorene vinylene-co-thiophene vinylene (FV) (90 : 10) (C1) and poly(fluorene vinylene-co-thiophene vinylene (FV) (80 : 20) (C2) were significantly increased, but their LUMO energy levels were slightly decreased. The optical properties were investigated by absorption and emission spectra of the polymers. The good spectral overlap between the emission of poly(FV) and the absorption of polymers C1 and C2 revealed a sufficient energy transfer from the majority of 9,9-di-iso-octylfluorene vinylene units to the minority of ThV units. The reduction of self-absorption losses of polymers C1 and C2 due to spectral separation caused by the incorporation of ThV units could be indirectly confirmed by nonlinear optical (NLO) properties. The result of the NLO properties of the polymers showed that the third-order NLO coefficients of poly(FV), C1, and C2 were 8.1 3 10 210 , 1.35 3 10 29, and 1.51 3 10 29 esu, respectively.

Tetraphosphonated thiophene ligand: mixing the soft and the hard

“…The synthetic procedure to obtain ligand L T H 8 is depicted in Scheme 1. Although 2,5-dibromomethylthiophene 1 can be obtained by bromination of dimethylthiophene 11 or of the dihydroxymethyl precursor, 12 it was found that the reaction with formaldehyde and bromhydric acid in acetic acid 13 was a very convenient way to obtain the target dibromo intermediate in fair yields. Two nucleophilic substitution reactions at the bromo positions using tetra-ethyliminobis(methanephosphonate) 14 afforded the ethyl ester protected precursor of L T H 8 , 2.…”

Conjugated 4‐Methoxybipyrrole Thiophene Azomethines: Synthesis, Opto‐Electronic Properties, and Crystallographic Characterization

“…Enhanced properties for improved color transitions have arrived from incorporating unsaturated linkages into conjugated materials, which may exhibit extended degrees of conjugation through coplanar aryl units. [8,[21][22][23][24][25][26] For example, vinyl links have shown promise for preparing new functional materials; however, their synthesis by Gilch and Horner-Emmons protocols, often requires rigorous reaction conditions (i. e., anhydrous solvent and inert atmosphere), lacks atom economy and necessitates tedious product purification. [21,22] On the other hand, azomethines ( À N=CH À ) are isoelectronic to their vinyl counterparts, [27] however, their synthesis is relatively straightforward and efficient, involving condensation of amine and aldehyde components to produce the conjugate and water, facilitating purification.…”

“…[8,[21][22][23][24][25][26] For example, vinyl links have shown promise for preparing new functional materials; however, their synthesis by Gilch and Horner-Emmons protocols, often requires rigorous reaction conditions (i. e., anhydrous solvent and inert atmosphere), lacks atom economy and necessitates tedious product purification. [21,22] On the other hand, azomethines ( À N=CH À ) are isoelectronic to their vinyl counterparts, [27] however, their synthesis is relatively straightforward and efficient, involving condensation of amine and aldehyde components to produce the conjugate and water, facilitating purification. [28][29][30] In spite of their practical synthesis, conjugated materials incorporating azomethines and heterocycles have not been pursued, likely because homoaryl azomethine counterparts exhibited properties incompatible for devices, such as poor electrochromic behavior and high E pa.…”

A fluorescent all-fluorene polyazomethine—towards soluble conjugated polymers exhibiting high fluorescence and electrochromic properties

“…This is in part owing to their inherent high fluorescence yield that is well suited for such emitting applications. Although fluorescent polymers have been successfully prepared using Yamamato, Stille, Suzuki, Gilch and Horner-Emmons coupling protocols, [1][2][3][4][5] these require stringent reaction conditions. The resulting polymers must further be extensively purified to remove undesired by-products for obtaining pristine polymers required for preparing efficient emitting materials with high color purity.…”