Synthesis and Properties of Terthiophene and Bithiophene Derivatives Functionalized by BF₂ Chelation: A New Type of Electron Acceptor Based on Quadrupolar Structures

Abstract

Terthiophene and bithiophene derivatives functionalized by BF(2) chelation were synthesized as a new type of electron acceptor, and their properties were compared to those of bifuran and biphenyl derivatives. These new compounds are characterized by quadrupolar structures due to resonance contributors generated by BF(2) chelation. The bithiophene derivative has a strong quadrupolar character compared with the bifuran and biphenyl derivatives because their hydrolytic analyses indicated that the bithiophene moiety has a larger on-site Coulomb repulsion than the others. The terthiophene derivative has a smaller on-site Coulomb repulsion than the bithiophene derivative due to the addition of a thiophene spacer. These BF(2) complexes exhibit long-wavelength absorptions and according to measurements of ionization potentials and absorption edges they have energetically low-lying HOMOs and LUMOs. The crystal structure of the bithiophene derivative is of the herringbone type, with short F···S and F···C contacts affording dense crystal packing. n-Type semiconducting behaviour was observed in organic field-effect transistors based on these BF(2) complexes.

Recent progress of optical functional nanomaterials based on organoboron complexes with β-diketonate, ketoiminate and diiminate

“…Various types of asymmetric complexes and tunable emissions have been reported. [24][25][26][27][28][29][30][31][32][33][34] Emission colors can be modulated both in the solution and in solid states. In addition, a photo-responsive ketoiminate was obtained using a dithienylethene unit.…”

Pd‐Catalyzed Functionalization of the Thenoyltrifluoroacetone Coligands by Aromatic Dyes in Bis(cyclometallated) IrIII Complexes: From Phosphorescence to Fluorescence?­

“…Then, the condensation of the latter with ethyl trifluoroacetate in the presence of a base afforded the ttaHAr proligands 2a-2f (Schemes 4 and 5). [15] The chromophores were used as their bromo derivatives in the catalytic reactions {conditions: Pd(OAc) 2 or PdCl(C 3 H 5 )(dppb) [dppb = bis(diphenylphosphino)butane], DMA, KOAc, 150°C, 48 h}. The new thiophene derivatives th-Ar [Ar = m-C 6 H 4 -CF 3 (th-PhCF 3 , 1a), naphthyl (th-Napht, 1b), pyrene (th-Pyr, 1c), perylene (th-Per, 1d), naphthalimide (th-NI, 1e) and coumarin (th-Coum, 1f)] were obtained in moderate to high yields.…”

“…In all cases, the reaction was regiospecific in favour of the arylation at the 5-position of the thienyl ring. The ttaH-Ar proligands 2a-2f were then obtained according to a reported procedure [15] with ethyl trifluoroacetate as the reactant and lithium bis(trimethylsilyl)amide [LiN(TMS) 2 ] as the base (Scheme 5). All of the target compounds 2a-2f were isolated in high yields after column chromatography.…”

Thienyl Difluoroboron β-Diketonates in Solution and Polylactide Media

“…Thiophene-based materials, mainly oligo- and polythiophenes, are thought to be some of the most versatile conjugated materials. 31,32 However, weak emission in these materials is typically attributed to the inclusion of the heavy sulfur atom, as well as the efficient solid-state packing characteristic for thiophene-based materials, shown by Ono et al 33,34 However, the presence of an electron-rich thienyl ring can act as an electron-donating group, and the heavy atom inclusion may assist favorable dual-emissive properties when confined to a rigid matrix.…”