Block modification of rod-shaped π conjugated carbon frameworks with donor and acceptor groups toward highly fluorescent molecules: synthesis and emission characteristics
作者:Takanori Ochi、Yoshihiro Yamaguchi、Tateaki Wakamiya、Yoshio Matsubara、Zen-ichi Yoshida
DOI:10.1039/b717832h
日期:——
To create organic molecules that are highly fluorescent at a longer wavelength region, we investigated the synthesis (using Pd-catalyzed cross-coupling) and photophysical properties (Φf, λem, Ï, λabs, and ε) of the following Ï conjugated molecular rods consisting of p-phenyleneethynylene units modified by donor (OMe) and/or acceptor (CN) groups: (1) side-donor modification systems (SD systems), (2) side-acceptor modification systems (SA systems), and (3) systems consisting of a donor block and an acceptor block (BL systems). As a consequence, very high Φf values (>0.95) were obtained for BL systems. Bathochromic shifts of λem for the same Ï conjugation length were largest for BL systems. Thus we succeeded in creating highly efficient light emitters at a longer wavelength region by block modification (e.g., Φf = 0.97, λem = 464 nm for BL-9). Considerably intense solid emission (Φf â¼ 0.5) at a longer wavelength region (500â560 nm) was also found for BL systems. It has been found that BL-6 and BL-8 exhibit interesting two photon absorption characteristics.
A Brönsted acid-promoted trifluoromethylselenolation of benzofurans was disclosed by using Se-(trifluoromethyl) 4-methylbenzenesulfonoselenoate as a stable and easily prepared electrophilic trifluoromethylselenolating reagent. A wide range of SeCF3-substituted benzofuran derivatives were obtained in moderate to good yields with excellent regioselectivity. The tandem cyclization/trifluoromethylselenolation
electrophiles via Ar–C(O) cleavage remains a challenging yet highly desirable transformation in Sonogashira-type coupling. Herein, we report a palladium-catalyzed ligand-promoted alkynylation of unstrained aryl ketones. The protocol allows the alkynylation to be carried out in a one-pot procedure with broad functional-group tolerance and substrate scope. The potential applications of this protocol
A two-step, one-pot tandem iodocyclization and trifluoromethylation have been developed. A variety of 3-trifluoromethylbenzofurans were prepared in moderate to good yields via the tandem reaction of 2-alkynylanisoles with elemental iodine and (trifluoromethyl)trimethylsilane.