Switches Based on DHA-VHF

The photoproduct is formed by a singlet pathway 1DHA — VHF triplet states are not involved in this reaction. Fluorescence is observed, weakly in fluid solution and with greatest efficiency in glasses at low temperature (also see above, for crystal packing effects). The increase in ( )F at low temperature is accompanied by a notably retarded DHA— VHF process, indicating competition between the photochemical 

Lower plot No switching occurred at working potential -800 mV vs. Fc/Fc+. 

12 (b). Irradiation was performed using an Osram HWLS 500 W lamp as the light source. 

One approach towards such a system was accomplished by the synthesis and examination of (S)-l,T-binaphthyl-2,2 -diyl bis[4-(l,l-dicyano-l,8a-dihydro-(8aS)-azu-len-2-yl)]-benzoate (30a), monitoring its photochromic behavior by UV/Vis and CD spectroscopy. After irradiation of a solution of 30a in acetonitrile for 15.5 min, fundamentally altering its spectral properties, subsequent thermal relaxation in the dark for 12h resulted in complete restoration of the UV/Vis and CD spectra. This is a first step towards a powerful DHA/VHF-based information storage system controlled by asymmetric induction. Further investigations are underway. 

Switching of the redox properties of (35-40)a has been examined by means of cyclic voltammetry and UV/Vis/NIR spectroelectrochemistry. For all DHA-VHF couples, we have observed three different I/E (current/potential) responses  

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