Lu, Xuefeng published the artcileControlling the Charge Transfer in D-A-D Chromophores Based on Pyrazine Derivatives, SDS of cas: 52431-30-8, the publication is Journal of Organic Chemistry (2014), 79(14), 6480-6489, database is CAplus and MEDLINE.
A series of sym. donor-acceptor-donor (D-A-D) chromophores bearing various electron-withdrawing groups, such as quinoxaline (Qx), benzo[g]quinoxaline (BQ), phenazine (Pz), benzo[b]phenazine (BP), thieno[3,4-b]pyrazine (TP), and thieno[3,4-b]quinoxaline (TQ), was designed and synthesized. Intramol. charge transfer (ICT) interactions can be found for all the chromophores due to the electron-withdrawing properties of the two imine nitrogens in the pyrazine ring and the electron-donating properties of the other two amine nitrogens in the two triphenylamines. Upon the fusion of either benzene or thiophene ring on the pyrazine acceptor unit, the ICT interactions are strengthened, which results in the bathochromically shifted ICT band. Moreover, the thiophene ring is superior to the benzene ring in enlarging the ICT interaction and expanding the absorption spectrum. Typically, when a thiophene ring is fused on the Qx unit in DQxD, a near-IR dye is realized in simple chromophore DTQD, which displays the maximum absorption wavelength at 716 nm with the threshold over 900 nm. This is probably due to the enhanced charge d. on the acceptor moiety and better orbital overlap, as revealed by theor. calculation These results suggest that extending the conjugation of a pyrazine acceptor in an orthogonal direction to the D-A-D backbone can dramatically improve the ICT interactions.
Journal of Organic Chemistry published new progress about 52431-30-8. 52431-30-8 belongs to bromides-buliding-blocks, auxiliary class Liquid Crystal &OLED Materials, name is 2,5-Dibromo-3,4-dinitrothiophene, and the molecular formula is C4Br2N2O4S, SDS of cas: 52431-30-8.
Referemce:
https://en.wikipedia.org/wiki/Bromide,
bromide – Wiktionary