Fatigue of photochromic materials

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. 

Note Mechanical stimuli such as stresses and strains may produce cracks or fracture in a material. Loss of function of a photochromic material resulting from cyclic irradiation may also be considered fatigue. 

My reservations were based on the fatigue of the HABIs, the weak colors that were formed, and the likelihood that these colors would fade, rather than reverse themselves. I also suspected that the fact that no one had really succeeded in commercializing any photochromic materials was because the fatigue reaction was too considerable an obstacle. I said to some of my friends that the academic scientists who reported in this field were content with a few dozen reversals, which might be achieved by low quantum yields of formation, and so there was an ample reservoir of dimers, provided one did not push too hard. 

Jeong, Y.-C., Yang, S.I., Kim, E., Ahn, K.-H., 2006h. Development of highly fluorescent photochromic material with high fatigue resistance. Tetrahedron 62 (25), 5855—5861. 

Patel, P.D., Mikhailov, I.A., Belfield, K.D., Masrmov, AJi., 2009. Theoretical study of photochromic compounds. Part 2 Thermal mechanism for byproduct formation and fatigue resistance of diary lethenes used as data storage materials. International Journal of Quantum Chemistry 109 (15), 3711-3722. 

Among various photoresponsive compounds, dithienylethene (DE) derivatives are the most feasible photochromic materials due to their outstanding fatigue resistance, thermal stability, and reversible properties [65-67]. Addition of this photoresponsive moiety into an aromatic conjugated polymer is attractive as a method of dynamic control of luminescence through photoisomerization-driven... 

As it is well known, photochromic materials have a wealth of applications, from sunglasses to information storage. The research on how these systems can be tuned (reversibility, rate and quantum yield in either direction, fatigue) by chemical elaboration is very active. In depth mechanistic studies with a variety of techniques have been carried out. 

Diarylethenes are one of the most promising photochromic materials for such purposes as molecular optical memories and switches, because of their excellent thermal stability and fatigue-resistant nature [51]. A chiral dithienylethene has the potential for non-destructive readout by detecting optical rotation at wavelengths longer than its own absorption band. However, it is not a simple task to achieve appreciable stereoselectivity in solution-phase photocyclization of dithienylethenes, even for those with chiral substituents [52-54]. In this regard, a... 

Fulgides and Fulgimides - A theoretical study of the photochromic compound 2,3-bis(2,4,5-trimethyl-3-thienyl)maleic anhydride has been reported. The photochromic properties of the indyl fulgide ( )-l-benzyl-2-methyl-3-indylethylindene(isopropylidene) succinic anhydride have been studied.The photochromism of (232) and (233) has been investigated. The cyclizations are reversible and the materials show reasonable fatigue resistance. 

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