Theoretical studies on structure and performance of [1,2,5]-oxadiazolo-[3,4-d]-pyridazine-based derivatives

4,7-Di(9H-carbazol-9-yl)-[1,2,5]oxadiazolo[3,4-d]pyridazine

Donor–acceptor–donor (D–A–D)-type molecules are considered as a promising class of NIR fluorescence materials. In this communication, 4,7-di(9H-carbazol-9-yl)-[1,2,5]oxadiazolo[3,4-d]pyridazine was obtained by dehydrogenation of 4,7-bis(1,2,3,4,4a,9a-hexahydro-9H-carbazol-9-yl)-[1,2,5]oxadiazolo[3,4-d]pyridazine with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in toluene. The structure of the synthesized compound was established by elemental analysis; high-resolution mass spectrometry; 1H, 13C NMR, IR, and UV spectroscopy; and mass spectrometry. The photophysical properties of the title compound were studied and compared with spectral data of the [1,2,5]thiadiazolo[3,4-d]pyridazine analogue.

Screening for energetic compounds based on 1,3-dinitrohexahydropyrimidine skeleton and 5-various explosopheres: molecular design and computational study

In this paper, twelve 1,3-dinitrohexahydropyrimidine-based energetic compounds were designed by introducing various explosopheres into hexahydropyrimidine skeleton. Their geometric and electronic structures, heats of formation (HOFs), energetic performance, thermal stability and impact sensitivity were discussed. It is found that the incorporation of electron-withdrawing groups (-NO2, -NHNO2, -N3, -CH(NO2)2, -CF(NO2)2, -C(NO2)3) improves HOFs of the derivatives and all the substituents contribute to enhancing the densities and detonation properties (D, P) of the title compounds. Therein, the substitution of -C(NO2)3 features the best energetic performance with detonation velocity of 9.40 km s-1 and detonation pressure of 40.20 GPa. An analysis of the bond dissociation energies suggests that N-NO2 bond may be the initial site in the thermal decompositions for most of the derivatives. Besides, -ONO2 and -NF2 derivatives stand out with lower impact sensitivity. Characters with striking detonation properties (D = 8.62 km s-1, P = 35.08 GPa; D = 8.81 km s-1, P = 34.88 GPa), good thermal stability, and acceptable impact sensitivity (characteristic height H50 over 34 cm) lead novel compounds 5,5-difluoramine-1,3-dinitrohexahydropyrimidine (K) and 5-fluoro-1,3,5-trinitrohexahydropyrimidine (L) to be very promising energetic materials. This work provides the theoretical molecular design and a reasonable synthetic route of L for further experimental synthesis and testing.

Effect of π-bridge units on properties of A–π–D–π–A-type nonfullerene acceptors for organic solar cells

We theoretically designed efficient nonfullerene acceptors (P2 and P5) with lower LUMO energies and higher electron transport abilities for OSCs.