59918-60-4

Original tetrazines substituted by heterocyclic rings have been prepared. Their syntheses, as well as their electrochemical and spectroscopic features, are described. Calculations have also been made on the cation radicals, anion radicals and neutral compounds and are in correct agreement with the experimental results. All compounds are electroactive, both in oxidation and reduction, and display two absorption bands in the UV and visible regions of the spectrum. Reduction potentials and maximum wavelengths are correlated with the electron-rich character of the heterocyclic substituent on the tetrazine ring. None of these compounds gives good quality polymers upon electro-oxidation, which was unexpected, especially for the bis(2-pyrrolyl) tetrazine. This latter result can be explained by the occurrence of a self-deprotonation equilibrium in the cation radical.

Provided are: an iridium complex represented by formula (1); and an organic electroluminescent element which uses the iridium complex as a phosphorescent dopant material. The organic electroluminescent element can exhibit good performance, such as reduced driving voltage, improved current efficiency, or a long half-life period.

Provided is an additive for imparting low heat build-up to a rubber component, wherein the additive includes a tetrazine compound represented by general formula (1): (wherein X1 and X2 are the same or different and represent a hydrogen atom or an alkyl, alkylthio, aralkyl, aryl, arylthio, heterocyclic, or amino group; and each of these groups may have one or more substituents), or a salt thereof.

The present invention relates to compounds that are electron-deficient acceptors, donor- acceptor polymers that are synthesized from such electron-deficient acceptors, semiconductor devices synthesized from such donor-acceptor polymers and methods of synthesis of such electron-deficient acceptors, donor-acceptor polymers and semiconductor devices.

Two donor-acceptor polymer semiconductors based on highly electron-deficient pyrrolo[3,4-d]pyridazine-5,7-dione unit were synthesized by Stille cross-coupling polymerization, and their thermal property, photophysical property, electrochemical property, microstructure, application as organic thin-film transistors, and photovoltaic property were investigated. Because of the strong electron-accepting characteristic of pyrrolo[3,4-d]pyridazine-5,7-dione, the new polymers (P1 and P2) exhibited much wider absorption, smaller bandgaps (1.70 vs 1.98 eV), and deeper LUMO levels (-3.60 vs -3.37 eV) than those of a phthalimide-based polymer PBDT-PhBT (Figure 1). The fabricated organic thin-film transistor devices exhibited hole-transport behavior, and the highest mobility of 1.14 × 10-3 cm2 V-1 s-1 was obtained. The bulk-heterojunction solar cells based on the two polymers as the electron donors and PC71BM as the electron acceptor showed a high open-circuit voltage and achieved a power conversion efficiency of 2.71% and 3.66% for polymers P1 and P2, respectively.

A new electron acceptor 6-alkylpyrrolo[3,4-d]pyridazine-5,7-dione (PPD) with a very low LUMO level has been synthesized via a challenging inverse electron demand Diels-Alder reaction between thiophene and furan-decorated tetrazine substrates and an electron-deficient 1-alkyl-1H-pyrrole-2,5-dione unit. The PPD monomer has been incorporated into a series of donor-acceptor-type conjugated polymers as electrochromic materials with good optical contrast, fast switching speed, and high coloration efficiency.

A mild and efficient protocol for the construction of 1,4-dihydro-3,6- disubstituted-1,4-bis(p-toluenesulfonyl)-1,2,4,5-tetrazines from p-toluenesulfonyl hydrazones mediated by [hydroxyl(tosyloxy)iodo]benzene in the presence of pyridine has been developed. This protocol affords the products in good to excellent yields. The corresponding 3,6-disubstituted-1,2,4,5-tetrazines can be easily obtained through one-step N-deprotection of p-toluensulfonyl groups and aromatization by tetrabutyl ammonium fluoride in THF. A mechanism has been proposed.

Two series of new soluble conjugated compounds containing tetrazine central ring have been synthesized. The three-ring compounds have been synthesized by the reaction of aryl cyanide (where aryl = thienyl, alkylthienyl, phenyl or pyridyl) with hydrazine followed by oxidation of the intermediate product with diethyl azodicarboxylate. The five-ring compounds have been prepared using two pathways: (i) reaction of 5-cyano-2,2′-bithiophene (or its alkyl derivative) with hydrazine; (ii) via Suzuki or Stille coupling of 3,6-bis(5-bromo-2-thienyl)-1,2,4,5-tetrazine with a stannyl or boronate derivative of alkylthiophene. UV-vis spectroscopic properties of the synthesized compounds are strongly dependent on the nature of the aryl group, the position of the solubilizing substituent and the length of the molecule, showing the highest bathochromic shift (λmax > 440 nm) for five-ring compounds with alkyl groups attached to Cα carbon in the terminal thienyl ring. An excellent linear correlation has been found for spectroscopically determined and theoretically calculated (TD-B3LYP/6- 31G*) excitation energies. With the exception of dipyridyl derivative, the calculated lowest unoccupied molecular orbital (LUMO) level of the investigated molecules changes within a narrow range (from -2.63 to -2.41 eV), in line with the electrochemical data, which show a reversible reduction process with the redox potential varying from -1.23 V to -1.33 V (vs. Fc/Fc+). The electrochemically determined positions of the LUMO levels are consistently lower by 0.9 to 1.2 eV with respect to the calculated ones. All molecules readily crystallize. Single crystal studies of 3,6-bis(2,2′-bithien-5-yl)-1,2,4,5- tetrazine show that it crystallizes in a P21/c space group whose structural arrangement is not very favorable to the charge carriers flow within the crystal. Powder diffraction studies of other derivatives have shown that their structural organization is sensitive to the position of the solubilizing substituent. In particular, the presence of alkyl groups attached to C α carbon in the terminal thienyl ring promotes the formation of a lamellar-type supramolecular organization.

Upon UV-irradiation 2,5-diaryl-1,3,4-oxadiazoles 2a-g do not undergo (2+2)-cycloaddition with 1,3-dimethyluracil, but instead ring cleavage occurs to afford the benzoylhydrazones 3a-e as well as the decomposition products 4-6.With 6-chloro-1,3-dimethyluracil (1b) 3h is formed, which in turn photoeliminates benzoyl chloride to give the pyrazolopyrimidine 7.Saponification of 3a gives smoothly 5-benzoyl-1,3-dimethyluracil (photoselective 5-benzoylation). - A new and simple synthesis of 3,6-disubstituted 1,2,4,5-tetrazines from aroylhydrazines is described, employing the system triphenylphosphane/hexachloroethane/triethylamine.