Synthesis and Isomeric Effects of Ladder-Type Alkylated Terbenzodithiophene Derivatives

Abstract

A new class of heptacyclic ladder-type terbenzodithiophene (TBDT) structures merging three fused benzodithophenes was developed. Two TBDT conjugated isomers, named as syn-TBDT and anti-TBDT, where the two thienyl rings in the outmost BDT units are in the syn- and anti-fashion, are designed. Two decyl groups are introduced to their 6,13 and 7,14-positions to form four isomeric 6,13-syn-TBDT, 7,14-syn-TBDT, 6,13-anti-TBDT, and 7,14-anti-TBDT structures which are constructed by the DBU-induced 6-benzannulation involving propargyl-allenyl isomerization of the dieneyne moieties in the corresponding precursors followed by 6π-electrocyclization/aromatization, while isomeric TD-syn-TBDT and TD-anti-TBDT with four decyl groups substituted at 6,7,13,14-positions are synthesized via palladium-catalyzed dialkylacetylene insertion/C-H arylation of the corresponding iodobiaryl precursors. The intrinsic properties can be modulated by molecular manipulation of the main-chain and side-chain isomeric structures. anti-TBDT derivatives exhibit higher melting points, larger bandgaps, stronger intermolecular interactions, and higher mobility than the corresponding syn-TBDT analogues. These molecules can be further utilized as building blocks to make various TBDT-based materials for optoelectronic applications.

Synthesis of Two‐Dimensional Terbenzodithiophene‐based Derivative by Palladium‐catalyzed C─H Benzannulation and Its Donor–Acceptor Copolymers for Organic Photovoltaics

“…Palladium‐catalyzed Sonogashira coupling reaction of 1,4‐diethynyl‐2,5‐dithiomethylbenzene ( 1 ) with 2‐iodothiophene ( 2 ) furnished the compound 3 . Reaction of 3 with I 2 resulted in the formation of the central iodinated BDT moiety in 4 . Palladium‐catalyzed benzannulation between an iodobiaryl and 1,2‐dialkylacetylene has been described by us previously .…”

“…Reaction of 3 with I 2 resulted in the formation of the central iodinated BDT moiety in 4 . Palladium‐catalyzed benzannulation between an iodobiaryl and 1,2‐dialkylacetylene has been described by us previously . Compound 4 was reacted with 1,2‐bis(5‐octylthiophen‐2‐yl)ethyne in the presence of Pd(OAc) 2 and pivalic acid to give TBDT‐4T with four octylthiophenyl groups at 6, 7, 13, and 14 positions.…”

“…However, the two substituents attached to the two sp 3 ‐hybridized carbons in BDCPDT would stick out of the conjugation plane and hinder the intermolecular π–π interactions. With the aim of reducing this steric hindrance, we synthesized a series of highly planarized terbenzodithiophenes (TBDT, Figure ) consisting of two sp 2 C=C moieties to fasten the central BDT unit and two outer thiophene units to form a heptacyclic arene . An easy and fast method was developed to construct a tetraalkylated TBDT by employing palladium‐catalyzed C─H benzannulation between an iodobiaryl group and a 1,2‐dialkylacetylene .…”

“…With the aim of reducing this steric hindrance, we synthesized a series of highly planarized terbenzodithiophenes (TBDT, Figure ) consisting of two sp 2 C=C moieties to fasten the central BDT unit and two outer thiophene units to form a heptacyclic arene . An easy and fast method was developed to construct a tetraalkylated TBDT by employing palladium‐catalyzed C─H benzannulation between an iodobiaryl group and a 1,2‐dialkylacetylene . It has been known that the replacement of aliphatic groups by conjugated alkylaryl groups on the polymer backbone could result in better thermal stability and light‐harvesting ability to further enhance the performance of photovoltaic devices .…”

Axisymmetric and Asymmetric Naphthalene-Bisthienothiophene Based Nonfullerene Acceptors: On Constitutional Isomerization and Photovoltaic Performance

“…Meanwhile when recalling the common isomeric phenomena in organic electronics, it is well-known that isomerization has a significant effect on the thermal-, optical-, and electrochemical-properties, charge carrier mobility, and eventually device performance. − Very recently, the constitutional isomeric effects of NFAs just have been investigated, − among which Zhan et al revealed that a NFA FNIC2 based on a thieno­[3,2- b ]­thiophene-fused benzo­[1,2- b :4,5- b′ ]­dithiophene core showed a red-shifted absorption, higher crystallinity, optimized morphology, and higher PCE of 13.0% than its isomer analogue FNIC1 (10.3%) . Huang et al developed configurational anti- and syn-isomers of dithienocyclopentapyrene-based NFAs, whereas the anti-isomer exhibited higher and more balanced hole/electron mobilities and thus better photovoltaic performance than the syn-isomer (6.07% vs 3.07%) .…”