Dicyanobenzothiadiazole (DCBT) Organic Dye as a Visible Light Absorbing Strong Photoinduced Oxidant with a 16 Microsecond Long-Lived Excited State

摘要

Strong photoinduced oxidants are important to organic synthesis and solarenergy conversion, to chemical fuels or electric. For these applications, visiblelight absorption is important to solar energy conversion and long-livedexcited states are needed to drive catalysis. With respect to these desirablequalities, a series of five 5,6-dicyano[2,1,3]benzothiadiazole (DCBT) dyes areexamined as organic chromophores that can serve as strong photooxidantsin catalytic systems. The series utilizes a DCBT core with aryl groups on theperiphery with varying electron donation strengths relative to the core. Thedyes are studied via both steady-state and transient absorption and emissionstudies. Additionally, computational analysis, voltammetry, crystallography,and absorption spectroelectrochemistry are also used to better understandthe behavior of these dyes. Ultimately, a strong photooxidant is arrived atwith an exceptionally long excited state lifetime for an organic chromophoreof 16 μs. The long-lived excited state photosensitizer is well-suited for use incatalysis, and visible light driven photosensitized water oxidation is demonstratedusing a water-soluble photosensitizer.