Blue to light gray electrochromic polymers from dodecyl‐derivatized thiophene Bis‐substituted dibenzothiophene/dibenzofuran

Abstract

3-Dodecylthiophene end-capped two monomers: 2,8-bis-(4-dodecyl-thiophen-2-yl)-dibenzothiophene (DBT-3DTh) and 2,8-bis-(4-dodecyl-thiophen-2-yl)-dibenzofuran (DBF-3DTh) were synthesized via Stille coupling reaction. Both monomers exhibited emission peaks at about 400 nm with fluorescence quantum yields ranging from 0.16 to 0.21. The corresponding electroactive polymers poly(2,8-bis-(4-dodecyl-thiophen-2-yl)dibenzothiophene) (PDBT-3DTh) and poly(2,8-bis-(4-dodecylthiophen-2-yl)-dibenzofuran) (PDBF-3DTh) were obtained by electropolymerization method and displayed good electrochemical stability. Both polymers switched between light gray in the neutral state and blue in the oxidized state. Kinetic inves-tigations showed that PDBT-3DTh exhibited a maximum optical contrast (DT %) of 25.23% at 575 nm with the coloration efficiency (CE) of 196 cm 2 C 21 . However, the electrochromic properties of PDBF-3DTh were inferior to PDBT-3DTh. Further detailed discussions with EDOT and 3-alkylthiophenes endcapped DBT/DBF hybrid electrochromic polymers were comparatively studied.

A Family of Superhelicenes: Easily Tunable, Chiral Nanographenes by Merging Helicity with Planar π Systems

“…Thus, we focused in our current work on employing precursors that have already a closed, central, five‐membered ring. Precursors 2,8‐dibromofluorenone 1 , [14] 2,8‐dibromofluorene 2 , [14] 2,8‐dibromodibenzofuran 3 , [15] 2,8‐dibromodibenzothiophene 4 [16] and 2,8‐dibromocarbazole 5 [17] were synthesized following adapted literature procedures starting from 9,10‐phenanthrenquionene, dibenzofuran, dibenzothiophene, and carbazole, respectively. The brominated precursors were then converted into the corresponding helicenes in an efficient three‐step synthesis.…”

“…It only proceeded cleanly under certain Scholl conditions.T hus,wefocused in our current work on employing precursors that have already ac losed, central, fivemembered ring. Precursors 2,8-dibromofluorenone 1, [14] 2,8dibromofluorene 2, [14] 2,8-dibromodibenzofuran 3, [15] 2,8dibromodibenzothiophene 4 [16] and 2,8-dibromocarbazole 5 [17] were synthesized following adapted literature procedures starting from 9,10-phenanthrenquionene,d ibenzofuran, dibenzothiophene,and carbazole,respectively.The brominated precursors were then converted into the corresponding helicenes in an efficient three-step synthesis.F irst, ad ouble Sonogashira reaction with 4-tert-butylphenylacetylene was performed to provide the necessary triple bonds for the subsequent Diels-Alder reactions.T hese were conducted with 2.5 equiv.o f2, 3,4,5-tetrakis[4-(tert-butyl)phenyl]cyclopenta-2,4-diene-1-one 24 in minimal amounts of toluene in pressure vials at high temperatures of 220 8 8C. Bis-hexaarylbenzenes 11-15 were reacted under classical Scholl conditions with FeCl 3 /MeNO 2 or DDQ/triflic acid in dichloromethane to afford superhelicenes 16-20.Despite the closure of 12 bonds in as ingle step,t he reaction proceeds cleanly.I ts hould be noted that 20 decomposes fast (within several hours) under ambient conditions.T his might be attributed to the strong + Me ffect of the NÀHm aking the HBC subunits very electron rich and reactive.Asimilar instability was observed by Müllen and co-workers for amino-HBC.…”

Colorless to Neutral Color Electrochromic Devices Based on Asymmetric Viologens

“…Thus, this system improves the performance of several polymer-based ECDs previously described in the literature which although they provided gray color in their neutral state, − partially doped state, − or full-doped oxidized state, − did not exhibit a colorless bleached state.…”

Multicolored Cathodically Coloring Electrochromism and Electrofluorochromism in Regioisomeric Star-Shaped Carbazole Dibenzofurans

“…It is worth noting that carbazole as an electron-rich heterocycle is traditionally regarded as an anodic unit in redox-active small molecules and polymers. − With this respect, the investigation of cathodic electrochemical properties and stability of the carbazole derivatives is significant not only for academic research but also for potential applications in electrochemical devices. In addition, dibenzofuran (DBF), a topologically similar heterocycle with more electronegative oxygen atom in the central ring (compared to nitrogen in Cz), while being less widespread, was also used as a building block in construction of molecular and polymeric semiconductors for organic electronics and optoelectronics, including OLEDs, − organic field-effect transistors (OFETs), electrochromics, and other applications. DBF is fluorescent and is less electron-rich than Cz (its highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) are E HOMO = −6.01 eV and E LUMO = −0.92 eV compared to −5.44 and −0.64 eV in carbazole, respectively, according to DFT B3LYP/6-31G­(d) calculations in the gas phase).…”