Iron-Catalyzed Tandem Cyclization of Diarylacetylene to a Strained 1,4-Dihydropentalene Framework for Narrow-Band-Gap Materials.
30 Apr 2021-Journal of the American Chemical Society (American Chemical Society (ACS))-Vol. 143, Iss: 18, pp 6823-6828
TL;DR: In this paper, an iron-catalyzed single-pot tandem cyclization of a diarylacetylene using FeCl2 and PPh3 as catalysts, magnesium/LiCl as reductant, and 1,2-dichloropropane as a mild oxidant is presented.
Abstract: Carbon bridging in a form of a strained 1,4-dihydropentalene framework is an effective strategy for flattening and stabilizing oligophenylenevinylene systems for the development of optoelectronic materials. However, efficient and flexible methods for making such a strained ring system are lacking. We report herein a mild and versatile synthetic access to the 1,4-dihydropentalene framework enabled by iron-catalyzed single-pot tandem cyclization of a diarylacetylene using FeCl2 and PPh3 as catalyst, magnesium/LiCl as a reductant, and 1,2-dichloropropane as a mild oxidant. The new annulation method features two iron-catalyzed transformations used in tandem, a reductive acetylenic carboferration and an oxidation-induced ring contraction of a ferracycle under mild oxidative conditions. The new method provides access not only to a variety of substituted indeno[2,1-a]indenes but also to their thiophene congeners, 4,9-dihydrobenzo[4,5]pentaleno[1,2-b]thiophene (CPTV) and 4,8-dihydropentaleno[1,2-b:4,5-b']dithiophenes (CTV). With its high highest occupied molecular orbital level and narrow optical gap, CTV serves as a donor unit in a narrow-band-gap non-fullerene acceptor, which shows absorption extending over 1000 nm in the film state, and has found use in a near-infrared photodetector device that exhibited an external quantum efficiency of 72.4% at 940 nm.
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TL;DR: In this paper , a triarylamine/bithiophene copolymer (TABT) was used as a hole-transporting material (HTM) in a solar cell.
Abstract: Polytriarylamine is a popular hole-transporting materials (HTMs) despite its suboptimal conductivity and significant recombination at the interface in a solar cell setup. Having noted insufficient conjugation among the triarylamine units along the polymer backbone, we inserted a bithiophene unit between two triarylamine units through iron-catalyzed C-H/C-H coupling of a triarylamine/thiophene monomer so that two units conjugate effectively via four quinoidal rings when the molecule functions as HTM. The obtained triarylamine/bithiophene copolymer ( TABT ) used as HTM showed a high-performance in methylammonium lead iodide perovskite (MAPbI 3 ) solar cells. Mesityl substituted TABT forms a uniform film, shows high hole-carrier mobility, and has an ionization potential (IP = 5.40 eV) matching that of MAPbI 3 . We fabricated a solar cell device with a power conversion efficiency of 21.3% and an open-circuit voltage of 1.15 V, which exceeds the performance of devices using reference standard such as poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine ( PTAA ) and Spiro-OMeTAD .
13 citations
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Abstract: Image-sensor technology is the foundation of many emerging applications, where the photodetector is designed to interact with incoming photons that have specific colors or wavelengths. A color filter is therefore crucial to enable the selective spectral response of the photodetector and to eliminate the crosstalk interference resulting from ambient lights. Unfortunately, a reduced detection sensitivity of the photodetector is inevitable due to an imperfect light filtering, which greatly limits the practical applications of selective-response photodetectors. Herein, we demonstrate a bulk-heterojunction (BHJ) organic composite featuring a self-filtering light responsive characteristic. Through a careful optimization of the BHJ film, the organic photodetector (OPD) demonstrates a high-selective spectral response to the infrared (IR) radiation without the need of applying a color filter. As a result, the self-filtering top-illuminated OPD exhibits a narrowband external quantum efficiency (EQE) of 53% with a narrow full width at half-maximum (fwhm) of 56 nm centering at 1080 nm. A high responsivity of 0.46 A W-1 is also achieved at 1080 nm wavelength due to the self-filtering characteristic.
6 citations
TL;DR: In this paper , an iron-catalyzed C-H/C-H heterocoupling between enamines and thiophenes was proposed for copolymerization of bisenamine and bisthiophene using diethyl oxalate as an oxidant and AlMe3 as base.
Abstract: C-H/C-H coupling via C-H activation provides straightforward synthetic access to the construction of complex π-conjugated organic molecules. The palladium-catalyzed Fujiwara-Moritani (FM) coupling between an arene and an electron-deficient olefin presents an early example but is not applicable to enamines such as N-vinylcarbazoles and N-vinylindoles. We report herein iron-catalyzed C-H/C-H heterocoupling between enamines and thiophenes and its application to copolymerization of bisenamine and bisthiophene using diethyl oxalate as an oxidant and AlMe3 as a base, as a result of our realization that synthetic limitations in oxidative C-H/C-H couplings imposed by the high redox potential of the Pd(II)/Pd(0) catalytic cycle can be circumvented by the use of iron, which has a lower Fe(III)/Fe(I) redox potential. The trisphosphine ligand provides a coordination environment for iron to achieve the reaction's regio-, stereo-, and chemoselectivity. The reaction includes C-H activation of thiophene via σ-bond metathesis and subsequent enamine C-H cleavage triggered by nucleophilic enamine addition to the Fe(III) center, thereby differing from the FM reaction in mechanism and synthetic scope. The copolymers synthesized by the new reaction possess a new type of enamine-incorporated polymer backbone.
6 citations
TL;DR: In this paper , an iron(III) chloride mediated para-selective C−H chlorination and subsequent annulation of 2-amidophenol to synthesize C5- and C5, C7-chlorinated benzoxazoles was developed.
Abstract: Iron(III) chloride mediated para-selective C−H chlorination and subsequent annulation of 2-amidophenol to synthesize C5- and C5, C7-chlorinated benzoxazoles was developed. Further, the oxidative cross-dehydrogenative coupling of amidophenol with anisole by ferric chloride was explored to achieve the remotely anisylated benzoxazoles.
2 citations
TL;DR: In this article , an efficient and workable method for the reduction of imines via hydroboration with HBpin was developed, where the low-cost and non-toxic Fe exhibits high catalytic activity to this method, and a large range of aldimines comprising diverse aryl groups, alkyl groups and heterocycles were used to yield secondary amines.
1 citations
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