Benzodicarbomethoxytetrathiafulvalene Derivatives as Soluble Organic Semiconductors

Synthesis of 2-(Methylthio)-1,3-dithioles from 1,3-Dithiole-2-thiones: Important Building Blocks in Tetrathiafulvalene Chemistry

2-(Methylthio)-1,3-dithioles are important heterocyclic compounds used for the preparation of redox-active derivatives of tetrathiafulvalene as they serve as precursors for phosphonate esters that can be employed in Horner-Wadsworth-Emmons olefination reactions. Here, we present a mild and less hazardous method than previous methods for converting readily accessible 1,3-dithiole-2-thiones into 2-(methylthio)-1,3-dithioles by methylation with trimethyl orthoformate and HBF4·Et2O and a subsequent reduction with NaBH4.

Semiconductor Porous Hydrogen-Bonded Organic Frameworks Based on Tetrathiafulvalene Derivatives

Herein, we report on the use of tetrathiavulvalene-tetrabenzoic acid, H₄TTFTB, to engender semiconductivity in porous hydrogen-bonded organic frameworks (HOFs). By tuning the synthetic conditions, three different polymorphs have been obtained, denoted MUV-20a, MUV-20b, and MUV-21, all of them presenting open structures (22, 15, and 27%, respectively) and suitable TTF stacking for efficient orbital overlap. Whereas MUV-21 collapses during the activation process, MUV-20a and MUV-20b offer high stability evacuation, with a CO₂ sorption capacity of 1.91 and 1.71 mmol g^–1, respectively, at 10 °C and 6 bar. Interestingly, both MUV-20a and MUV-20b present a zwitterionic character with a positively charged TTF core and a negatively charged carboxylate group. First-principles calculations predict the emergence of remarkable charge transport by means of a through-space hopping mechanism fostered by an efficient TTF π–π stacking and the spontaneous formation of persistent charge carriers in the form of radical TTF^•+ units. Transport measurements confirm the efficient charge transport in zwitterionic MUV-20a and MUV-20b with no need for postsynthetic treatment (e.g., electrochemical oxidation or doping), demonstrating the semiconductor nature of these HOFs with record experimental conductivities of 6.07 × 10^–7 (MUV-20a) and 1.35 × 10^–6 S cm^–1 (MUV-20b).

Organocatalytic selective coupling of episulfides with carbon disulfide for the synthesis of poly(trithiocarbonate)s and cyclic trithiocarbonates

Selective coupling of CS2 with episulfides affords perfectly alternating poly(trithiocarbonate)s or cyclic trithiocarbonates upon the onium salts used.

Synthesis, photophysical properties, and density functional theory studies of phenothiazine festooned vinylcyclohexenyl-malononitrile

A novel phenothiazine derivative conjugated with vinylcyclohexenyl-malononitrile (PTZ-CDN) was synthesized through the Knoevenagel reaction of 10-octyl-10H-phenothiazine-3,7-dicarbaldehyde with 2-(3,5,5-trimethylcyclohex-2-en-1-ylidene)-malononitrile and fully characterized. The UV-vis absorption spectra of PTZ-CDN in different solvents showed a λ_max band at 497-531 nm with a high molar extinction coefficient attributed to intramolecular charge transfer (ICT) with the characteristics of a π-π* transition. Increasing the solvent polarity resulted in a bathochromic shift of λ_max . The PTZ-CDN fluorescence emission spectra were more sensitive to increasing the solvent polarity than the absorption spectra; they displayed a blue shift of λ_em by 85 nm. To understand the behaviour of the PTZ-CDN derivative, Stokes' shift ( Δ ν ¯ ) with respect to the solvent polarity, Lippert-Mataga and linear solvation-energy relationship (LSER) models were applied in which the LSER showed better regression than the Lippert-Mataga plots (r² = 0.9627). Finally, the TD-density functional theory (DFT) electronic transition spectra in dioxane and dimethyl formamide (DMF) were calculated. The DFT data showed that λ_max resulted from the support of the highest occupied molecular orbital to the lowest unoccupied molecular orbital transition with 74% and 99% in dioxane and DMF, respectively.

Research on charge-transport properties of TTF–TTP derivatives and organic interfaces

The electronic and charge transport properties of four derivative groups containing nineteen different derivative compounds were theoretically investigated by density functional theory (DFT) based on the Marcus–Hush theory.

HOMO stabilisation in π-extended dibenzotetrathiafulvalene derivatives for their application in organic field-effect transistors

Three new organic semiconductors, in which either two methoxy units are directly linked to a dibenzotetrathiafulvalene (DB-TTF) central core and a 2,1,3-chalcogendiazole is fused on the one side, or four methoxy groups are linked to the DB-TTF, have been synthesised as active materials for organic field-effect transistors (OFETs). Their electrochemical behaviour, electronic absorption and fluorescence emission as well as photoinduced intramolecular charge transfer were studied. The electron-withdrawing 2,1,3-chalcogendiazole unit significantly affects the electronic properties of these semiconductors, lowering both the HOMO and LUMO energy levels and hence increasing the stability of the semiconducting material. The solution-processed single-crystal transistors exhibit high performance with a hole mobility up to 0.04 cm(2)  V(-1)  s(-1) as well as good ambient stability.

PbS nanoparticles capped with tetrathiafulvalenetetracarboxylate: utilizing energy level alignment for efficient carrier transport

We fabricate a field-effect transistor by covalently functionalizing PbS nanoparticles with tetrathiafulvalenetetracarboxylate. Following experimental results from cyclic voltammetry and ambient-pressure X-ray photoelectron spectroscopy, we postulate a near-resonant alignment of the PbS 1Sh state and the organic HOMO, which is confirmed by atomistic calculations. Considering the large width of interparticle spacing, we observe an abnormally high field-effect hole mobility, which we attribute to the postulated resonance. In contrast to nanoparticle devices coupled through common short-chained ligands, our system maintains a large degree of macroscopic order as revealed by X-ray scattering. This provides a different approach to the design of hybrid organic-inorganic nanomaterials, circumvents the problem of phase segregation, and holds for versatile ways to design ordered, coupled nanoparticle thin films.

Facile synthesis and photo-physical properties of cyano-substituted styryl derivatives based on carbazole/phenothiazine

Four new cyano-substituted styryl derivatives based on carbazole and phenothiazine were facilely synthesized by conventional Knoevenagel condensation and well characterized. The UV-vis spectra of these dyes showed the lowest-energy absorption bands were mainly caused by the HOMO-LUMO one-electron promotion as conformed by TD-DFT calculations. The thermogravimetric analysis showed these dyes were thermally stable up to 350 °C. The UV-vis absorption and fluorescence emission spectra were also studied in solvents of different polarity, these dyes exhibited unusual large Stokes shift.