3,4-Ethylenedioxythiophene and 3,4-Ethylenedioxyselenophene: Synthesis and Reactivity of Cα−Si Bond

Silver-Mediated [2 + 2 + 1] Cyclization Reaction of Diynes with Elemental Selenium/Sulfur To Synthesize 3,4-Substituted Cyclopenta[c]selenophenes/Cyclopenta[c]thiophenes

An efficient and atom-economical silver-mediated [2 + 2 + 1] cyclization protocol for the synthesis of 3,4-fused-ring-substituted and 2,5-unsubstituted selenophenes or thiophenes has been developed. Two C-Se/C-S bonds and one C-C bond were rapidly constructed in one step. Readily accessible substrates, commercially available elemental selenium/sulfur, and good functional group tolerance make this procedure attractive for the synthesis of π-conjugated material molecules.

Recent advances in poly(3,4-ethylenedioxyselenophene) and related polymers

This review highlights the recent progress in synthesis, properties, applications and future outlook of PEDOS based conjugated polymers.

Poly(3,4-ethylenedioxyselenophene): effect of solvent and electrolyte on electrodeposition, optoelectronic and electrochromic properties

In this article, we report the effect of electropolymerization conditions such as solvent and supporting electrolyte on the redox, optoelectronic and electrochromic properties of PEDOS. Monomer EDOS was synthesized by new and simple route and its electropolymerization was investigated by employing six different combinations of solvent–electrolyte namely TBAClO₄/MeCN, TBAPF₆/MeCN, TBABF₄/MeCN, TBAClO₄/PC, TBAPF₆/PC and TBABF₄/PC. Further, the electrochemical, spectroelectrochemistry, morphology and electrochromic properties of resultant PEDOS films were systematically studied. A pronounced effect of both solvent and supporting electrolyte on the electropolymerization, redox, optoelectronic and electrochromic properties on PEDOS film is noted. Among all solvent–electrolyte systems, MeCN and TBAClO₄ were found to be the most suitable medium for electropolymerization of EDOS. Further, PEDOS films prepared in PC showed red shifted absorption maxima, narrow absorption peaks in UV-vis-NIR spectra, slightly more smooth morphologies, and high optical contrasts ratio and coloration efficiency in comparison to MeCN. PEDOS films prepared in TBABF₄/PC exhibited longer λ_max (670 nm), smooth morphology, and the highest optical contrasts ratio (44.6%) and coloration efficiency (141.8 cm² C⁻¹) compared to the other solvent–electrolyte medium.

In this article, we report the effect of electropolymerization conditions such as solvent and supporting electrolyte on the redox, optoelectronic and electrochromic properties of PEDOS.

Metallacyclopentadienes: synthesis, structure and reactivity

Metallacyclopentadienes, which possess two M-C(sp²) bonds and feature the structure of M(C[upper bond 1 start]R¹[double bond, length as m-dash]CR²-CR³[double bond, length as m-dash]C[upper bond 1 end]R⁴), are an important class of five-membered metallacycles. They are considered as both reactive intermediates in the stoichiometric and catalytic transformations of organic molecules and useful precursors to main group element compounds, and have received considerable attention in organometallic chemistry, coordination chemistry and synthetic organic chemistry over the past six decades because of their unique metallacyclic structure. This review comprehensively presents the synthesis, structure and reactivity of the s-, p-, d- and f-block metallacyclopentadienes distributed in the whole periodic table. In addition, their application in synthetic organic chemistry and polymer chemistry is summarized. This review aims to be beneficial for the design and synthesis of novel metallacyclopentadienes, and for promoting the rapid development of metallacyclic chemistry.

The impact of vinylene bridges and side chain alkyl groups on the solid state structures of tricyanovinyl-substituted thiophenes

The goal of this work is to examine the solid state structures of compounds that have been designed for increased conjugation and solubility, as these factors are important if these compounds are to be used in the solid state.

Direct synthesis of polysubstituted 2-aminothiophenes by Cu(II)-catalyzed addition/oxidative cyclization of alkynoates with thioamides

A facile and direct synthetic method was developed for the construction of structurally important 2-aminothiophenes in moderate to excellent yields (up to 91%), via Cu(II)-catalyzed addition/oxidative cyclization of readily available thioamides with alkynoates under an air atmosphere.

Conversion of zirconacyclopentadienes into metalloles: Fagan-Nugent reaction and beyond

Metalloles are derivatives of cyclopentadiene in which the methylene unit is replaced by a heteroatom, such as S, Se, Te, N, P, As, Sb, Bi, Si, Ge, Sn, B, Al, Ga, and so on. Many metallole derivatives have been widely used as photovoltaic cells, organic light emitting diodes (OLEDs), chemical sensors, electrochromic devices, microelectronic actuators, and organic field effect transistors (OFETs). In the meantime, many of them showed promising biological actives. Due to the similarity to cyclopentadiene, the anionic forms of metalloles were also widely explored in coordination chemistry. As a result, development of a general method for the formation of metalloles from available starting materials is highly desired. In this Account, we outline formation of various p-block element metalloles from zirconacyclopentadienes. The zirconacyclopentadienes can be easily prepared from two molecules of alkynes and a low-valent zirconocene species "Cp2Zr(II)" (Cp = cyclopentadienyl). Fagan and Nugent first reported the formation of main group metalloles from zirconacyclopentadiene, which provided a versatile approach for the construction of metalloles, especially for the formation of metalloles in heavier p-block elements. To further expand the substrate scope, a number of stepwise conversions were developed, which involve 1,4-dimetallo- or dihalo-1,3-butadiene as intermediates from zirconacyclopentadienes. Here, four processes are classified based on direct and indirect conversion of zirconacyclopentadienes into metalloles. Direct reaction of zirconacyclopentadienes with element halides afforded heterocycles of main group elements, which provided a versatile method for the synthesis of metalloles. Nonetheless, the reaction scope was restricted to heavier p-block elements such as S, Se, P, As, Sb, Bi, Ge, Sn, Ga, and In. And these reactions usually suffered low yields and long reaction time. Transmetalation of zirconacyclopentadiene with copper chloride greatly enriched the zirconacyclopentadiene chemistry. The synthesis of stannoles and pyrroles from zirconacyclopentadienes has been developed in the presence of CuCl. The direct reaction of the zirconacyclopentadienes with SiCl4 or R2SiCl2 does not give the desired silacyclopendadiene derivatives, even in the presence of CuCl. It can be circumvented by using dilithiated dienes from diiododienes, which are easily prepared by the iodination of zirconacyclopentadienes using CuCl as an additive. Finally, an umpolung strategy, reaction of electrophilic 1,4-diiodo-1,3-butadiene with nucleophilic amine or sulfide reagents, was successfully used in the formation of pyrroles and thiophenes.

Poly(3,4-ethylenedioxyselenophene) and its derivatives: novel organic electronic materials

Since the discovery of high conductivity in iodine-doped polyacetylene, many interesting conducting polymers have been developed. Of these, polythiophenes have been most studied as electronic materials, with poly(3,4-ethylenedioxythiophene) (PEDOT) and the water-soluble PEDOT-PSS being the most successful commercially used conducting polymers. The polyselenophene family together with poly(3,4-ethylenedioxyselenophene) (PEDOS) and its derivatives have been shown to have slightly different properties compared to these of polythiophene and PEDOT because of their different electron donating characters, aromaticities (selenophene vs thiophene), oxidation potentials, electronegativities, and polarizabilities (Se vs S). As a result, the polyselenophenes, especially PEDOS and its derivatives, show a lower band gap and higher-lying highest occupied molecular orbital (HOMO) levels compared with those of thiophene and the PEDOT family. In an organic materials context, the PEDOS family offers some advantages over PEDOT derivatives. This Account draws on computational studies, synthetic methods, electrochemical polymerizations, chemical polymerizations, and the materials properties of PEDOS and its derivatives to demonstrate the importance of these novel materials, which lie at the frontier of conducting polymer research. In particular, we show that (i) PEDOS derivatives have a lower band gap (about 0.2 eV) than the corresponding PEDOT derivatives. Consequently, PEDOS derivatives can absorb the solar spectrum more efficiently compared to PEDOT derivatives and the properties of optoelectronic devices based on neutral and doped PEDOS should be somewhat different from these of PEDOT. (ii) EDOS derivatives have a greater tendency to undergo electrochemical polymerization compared to EDOT derivatives and offer stable and smooth polymer films. (iii) The PEDOS backbone is more rigid than the PEDOT backbone. (iv) PEDOS derivatives are excellent electrochromic materials with high transparency, and have higher contrast ratio and coloration efficiency. (v) The PEDOS/C electrode offers better control over the formation and size of nanoparticles through Se···Pt interactions compared with the PEDOT/C electrode. In addition to this, we summarize the synthesis, electrochemical polymerization, materials properties, and computational studies of fused polyselenophene analogues, namely, poly(cyclopenta[c]selenophene), and a series of low band gap thieno- or selenolo-fused polyselenophenes and selenolo-fused polythiophene. Additionally, we discuss oxidative and solid state polymerization to obtain conducting PEDOS, and its derivatives, and made throughout comparison with S-analogue where applicable. We found that EDOS-based derivatives have a greater tendency toward solid state polymerization and working at a temperature about 20 °C lower than that required for EDOT-based compounds. Our results demonstrate the utility of EDOS unit for generating promising materials PEDOS and its derivatives for electronic devices. Consequently, EDOS structure is the basis for many functionalized polymers and copolymers with tunable optoelectronic and redox properties. These interesting properties, which include high conductivity, lower band gap, rigidity, multicolor electrochromism, and rapid redox switching, allow them to be used in a variety of electronic applications.