Anthracene-Based Zwitterion with a Small HOMO–LUMO Energy Gap

Abstract

We have designed and synthesized an anthracene-based zwitterion, 2-methyl-2-azoniaanthracene-7-olate. The zwitterion shows amphoteric redox properties and low-energy light absorption originating from the small HOMO‒LUMO energy gap of ca. 1.7 eV. DFT calculations show that the combination of replacing the C–H with N+–Me and introducing O− is necessary to alter the electronic structure and properties of anthracene significantly.

Organohalogenochromism (OHC) of D–π–A pyridinium dye polymer films and the colorimetric detection of volatile organic halogen compounds

“…[5][6][7][8][9][10][11][12] Bathochromic shift-type OHC (b-OHC) has been occasionally found in donor-p-acceptor (D-p-A) type dyes, which are composed of dialkyl or diaryl amino groups as a strong electron-donating moiety (D) and pyridinium, benzothiazolium, dicyanomethylene, and barbituric moieties as a strong electron-withdrawing moiety (A) connected by a p-conjugated bridge, and it can exhibit a photoabsorption band based on the intramolecular charge transfer (ICT) from the D moiety to the A moiety. [1][2][3][4][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28] However, few studies have been carried out on OHC although the phenomenon is of great scientific interest and practical importance, such as the development of optical sensors for the detection of toxic organohalogen compounds. [29][30][31][32][33][34][35] Actually, volatile organohalogen compounds (VOHCs) are commonly used in manufacturing, [36][37][38][39][40][41][42][43] but most of them are extremely toxic to human health, biolog...…”