Synthesis of unsymmetrical benzotrichalcogenophenes by N-heterocyclic carbene-palladium-catalyzed intramolecular direct C3-arylation of chalcogenophenes

Synthesis of 3,3'-(Ethane-1,2-diylidene)bis(indolin-2-one) Promoted by Thermally-activated Electron Transfer and Photoreduction of CO2 to CH4 and CO

A Sonogashira coupling reaction leads to the formation of a serendipitous product C with the 3,3'-(ethane-1,2-diylidene)bis(indolin-2-one) unit. To our knowledge, our study provides the first example demonstrating that electron transfer between isoindigo and triethylamine can be thermally activated and can be employed in synthesis. The physical properties of C suggest that it possesses decent photo-induced electron-transfer capabilities. Under the illumination of 136 mW cm-2 intensity, C yields ≈2.4 mmol gcat -1 (per gram of catalyst) of CH4 and ≈0.5 mmol gcat -1 of CO in 20 h in the absence of additional metal, co-catalyst, and amine sacrificial agent. The primary kinetic isotope effect suggests that the bond cleavage of water is a rate-determining step in the reduction. Moreover, the CH4 and CO production can be boosted as the illuminance increases. This study demonstrates that organic donor-acceptor conjugated molecules are potential photocatalysts for CO2 reduction.

Sequence-controlled alternating block polychalcogenophenes: synthesis, structural characterization, molecular properties, and transistors for bromine detection

Sequence-controlled polychalcogenophenes have attracted much interest in terms of synthesis, structure and function in polymer science. For the first time, we developed a new class of alternating block conjugated copolymers denoted as poly(alt-AB)x-b-(alt-AC)y where both blocks are constituted by an alternating copolymer. 3-Hexylthiophene (S), 3-hexylselenophene (Se) and 3-hexyltellurophene (Te) are used as A, B and C units to assemble three sequence-controlled polychalcogenophenes P(SSe)b(STe), P(SSe)b(SeTe) and P(STe)b(SeTe) which are prepared by adding two different Grignard monomers in sequence to carry out Ni(dppp)Cl2-catalyzed Kumada polymerization. The molecular weight, dispersity, and length of each block (x = y) and main-chain sequence can be synthetically controlled via the catalyst transfer polycondensation mechanism. The polymer structures, i.e. alternating block main chain with high side-chain regioregularity, are unambiguously confirmed by 1H-NMR and 13C-NMR. The optical and electrochemical properties of the polymers can be systematically fine-tuned by the composition and ratio of the chalcogenophenes. From GIWAXS measurements, all the polymers exhibited predominantly edge-on orientations, indicating that the packing behaviors of the alternating block polychalcogenophenes with high regioregularity are inherited from the highly crystalline P3HT. P(SSe)b(STe) exhibited a hole OFET mobility of 1.4 × 10-2 cm2 V-1 s-1, which represents one of the highest values among the tellurophene-containing polychalcogenophenes. The tellurophene units in the polymers can undergo Br2 addition to form the oxidized TeBr2 species which results in dramatically red-shifted absorption due to the alternating arrangement to induce strong charge transfer character. The OFET devices using the tellurophene-containing polychalcogenophenes can be applied for Br2 detection, showing high sensitivity, selectivity and reversibility.

Tellura(benzo)bithiophenes: Synthesis, Oligomerization, and Phosphorescence

A series of planar π-extended Te-containing heteroacenes, termed tellura(benzo)bithiophenes, were synthesized. This new structural class of heterocycle features a tellurophene ring fused to a benzobithiophene unit with aromatic side groups (either -C₆H₄ⁱPr or -C₆H₄OCH₃) positioned at the 2- and 5-positions of the tellurophene moiety. Although attempts to enhance molecular rigidity and extend ring-framework π-delocalization in a cumenyl (-C₆H₄ⁱPr)-capped tellura(benzo)bithiophene led to oxidation (and Te-C bond scission) to form a diene-one, the formation of an oligomeric tellura(benzo)bithiophene was possible via Kumada catalyst-transfer polycondensation (KCTP). Furthermore, one tellura(benzo)bithiophene derivative exhibits orange-red phosphorescence at room temperature in air when incorporated into a poly(methyl methacrylate) host; accompanying TD-DFT computations provided insight into a potential mechanism for the observed phosphorescence.

Recent Advances in the Synthesis of Selenophenes and Their Derivatives

The selenophene derivatives are an important class of selenium-based heterocyclics. These compounds play an important role in prospecting new drugs, as well as in the development of new light-emitting materials. During the last years, several methods have been emerging to access the selenophene scaffold, employing a diversity of cyclization-based synthetic strategies, involving specific reaction partners and particularities. This review presents a comprehensive discussion on the recent advances in the synthesis of selenophene-based compounds, starting from different precursors, highlighting the main differences, the advantages, and limitations among them.

Pd(II)-Catalyzed Direct Dehydrogenative Mono- and Diolefination of Selenophenes

Pd(II)-catalyzed dehydrogenative Heck olefination of selenophenes with a broad olefinic substrate scope and high functional group tolerance is demonstrated. Carbonyl-substituted and phenyl-substituted olefins with electron-donating (D) and electron-accepting (A) groups can be regioselectively installed at C2 of the selenophene. The 2-olefinated selenophenes can subsequently undergo a second oxidative olefination to rapidly produce a new class of symmetrical D-π-D or unsymmetrical D-π-A 2,5-diolefinated selenophene materials.

Palladium-catalyzed successive C–H bond arylations and annulations toward the π-extension of selenophene-containing aromatic skeletons

A modular approach for the synthesis of planar π-extended selenium containing molecules from selenophene has been developed.

One-pot synthesis of benzotripyrrole derivatives from 1H-pyrroles

Benzotripyrroles were synthesized in one step from functionalized pyrroles and computational studies reveal the reactivity of the pyrroles and stability of the benzotripyrroles.

Synthesis and self-assembly of thiol-modified tellurophenes

An asymmetric thiol-modified tellurophene was designed and synthesized, and the ability of the compound to form a monolayer on a gold electrode was confirmed. The surface-active tellurophene was synthesized using Cadiot–Chodkiewicz coupling followed by ring closing and thiol modification. The tellurophene compound forms a monolayer on gold surfaces from a concentrated solution within 24 h. The ability of the compound to conjugate to gold is confirmed by X-ray photoelectron spectroscopy (XPS). A surface blocking experiment was used to evaluate the extent of formation of a monolayer on a gold electrode.

Furo[2,3- g]thieno[2,3- e]indole: Application of an Ynamide-Based Benzannulation Strategy to the Synthesis of a Tetracyclic Heteroaromatic Compound

The first synthesis of the tetracyclic aromatic compound furo[2,3- g]thieno[2,3- e]indole ("FTI") is described. The synthetic strategy features a photochemical benzannulation based on the reaction of an α-diazo ketone and ynamide which assembles a benzothiophene equipped with substituents that enable subsequent cyclizations to generate the nitrogen and oxygen heterocyclic rings.

Synthesis of thieno[2,3-c]acridine and furo[2,3-c]acridine derivatives via an iodocyclization reaction and their fluorescence properties and DFT mechanistic studies

In this paper, we report the novel synthesis of thieno[2,3-c]acridine and furo[2,3-c]acridine derivatives via intramolecular iodocyclization reaction. The thieno[2,3-c]acridine derivatives exhibited blue fluorescence in hexane.