Amy Keirstead - Photochemical "triode" molecular signal transducer

Version 1

      Publication Details (including relevant citation   information):

      Amy E Keirstead,   James W Bridgewater,   Yuichi Terazono,   Gerdenis   Kodis,Stephen   Straight, Paul A Liddell,   Ana L Moore,   Thomas A Moore,   Devens Gust

      Journal of the American Chemical Society. 05/2010;   132(18):6588-95.


      A molecular "hexad" in which five bis(phenylethynyl)anthracene   (BPEA) fluorophores and a dithienylethene photochrome are   organized by a central hexaphenylbenzene unit has been prepared.   Singlet-singlet energy transfer among the BPEA units occurs on   the 0.4 and 60 ps time scales, and when the dithienylethene is in   the open form, the BPEA units fluoresce in the 515 nm region with   a quantum yield near unity. When the dithienylethene is   photoisomerized by UV light to the closed form, which absorbs in   the 500-700 nm region, the closed isomer strongly quenches all of   the excited singlet states of BPEA via energy transfer, causing   the fluorescence quantum yield to drop to near zero. This   photochemical behavior permits the hexad to function in a manner   analogous to a triode vacuum tube or transistor. When a solution   of the hexad is irradiated with steady-state light at 350 nm and   with red light (>610 nm) of modulated intensity, the BPEA   fluorescence excited by the 350 nm light is modulated   accordingly. The fluorescence corresponds to the output of a   triode tube or transistor and the modulated red light to the grid   signal of the tube or gate voltage of the transistor. Frequency   modulation, amplitude modulation, and phase modulation are all   observed. The unusual ability to modulate intense,   shorter-wavelength fluorescence with longer-wavelength light   could be useful for the detection of fluorescence from probe   molecules without interference from other emitters in   biomolecular or nanotechnological applications.

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