Fatigue diarylethenes

Masahiro Irie received his B.S. and M.S. degrees from Kyoto University and his Ph.D. in radiation chemistry from Osaka University. He joined Hokkaido University as a research associate in 1968 and started his research on photochemistry. In 1973 he moved to Osaka University and developed various types of photoresponsive polymers. In 1988 he was appointed Professor at Kyushu University. In the middle of the 1980 s he invented a new class of photochromic molecules - diaryl-ethenes - which undergo thermally irreversible and fatigue resistant photochromic reactions. He is currently interested in developing singlecrystalline photochromism of the diarylethene derivatives. 

Diarylethenes with thiophene or benzothiophene moieties exhibit excellent thermal stability and outstanding fatigue resistance (88JOC803 ... 

The primary difference, for our purposes, between furylfulgide derivatives and diarylethene derivatives is fatigue resistance. Diarylethenes have high durability col-... 

The fatigue resistance character of the following diarylethene was also examined in LB films.1171... 

A crucial point that must be addressed concerns the thermal stability and the fatigue phenomenon observed in the chromophores. It is a fact that many photo-chromic compounds are irreversibly degraded upon long exposure to light, thus limiting their use for various applications. Major advances in the preparation and performance of photochromic materials have been made in the past five years. Irie et al.11271 have recently developed new photochromic compounds, 1,2-diarylethenes, which display photochromic behavior with unchanged intensity even after 104 coloration decoloration cycles. 

Diarylethenes are promising synthetic photoswitchable molecules because of their outstanding fatigue-resistance in reversible light-induced transformation between two isomers with different absorption spectra.21,22 The tt-conjugation extends over the entire molecular in the closed form, whereas it is restricted to each half of the molecule in the open form. As a consequence, the closed form is expected to exhibit better electrical conductance than the open form. The two forms are referred to as the on and off states of the switch, respectively. The UV-vis spectra of this molecular switch in toluene show that the wavelengths that can be used for on to off switching are 420 < A< 650 nm, and 300 < A< 350 nm for the reverse operation. 

To realize the above-mentioned systems, we carefully chose suitable switching units and radical moieties. As an initial attempt, we employed l,2-bis(2-methyl-l-benzothiophen-3-yl)perfluorocyclopentene (9a) as a photochromic spin coupler (Scheme 9.2). Compound 9a is one of the most fatigue-resistant diarylethenes [21]. Nitronyl nitroxide was chosen for the spin source, because this radical is jr-conjugative. Thus, we designed molecule 10a, which is an embodiment of the simplified model 8a [37, 62]. 

Table 5.1. Fatigue-Resistant Properties of Diarylethenes in Benzene...

Diarylethenes undergo fatigue-resistant photochromic reactions [13]. Table 3 shows the fatigue-resistant properties of various diarylethenes. Benzene solutions... 

Table 3. Fatigue-resistant properties of diarylethenes in benzene.

Professor at Kyushu University. In the middle of the 1980 s he H invented a new class of photochromic molecules - diaryl-ethenes - which undergo thermally irreversible and fatigue resistant photochromic reactions. He is currently interested in developing singlecrystalline photochromism of the diarylethene derivatives. 

Thermally irreversible and fatigue-resistant photochromic diarylethene crystals have been developed in the past decade. The colored isomers are stable in the crystals, even at 100 °C and hardly return to the initial colorless isomers in the dark The thermally... 

A. Lucotti, C. Bertarelli, G. Zerbi, Optical fatigue in a solid state diarylethene polymer, Chem. Phys. Lett., 392, 549-554 (2004). 

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