Fulgides and Fulgimides

2 Fulgides and Fulgimides - The influence of conformational effects on the photochromism of the furylfulgide (263) has been examined. The effect on the absorption maximum of the coloured form of (264) by the introduction of methoxy substituents to the indole ring has been reported.  

2 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. 

The oxalylfulgides (129) have been prepared and studied. These photochromic yellow dyes undergo ring closure in the conventional manner. The quantum yields for the process and the solvent dependency results are shown below the struetures. A double Stobbe condensation of 3,5-dimethoxybenzaldehyde with succinic anhydride affords the fulgide (130). This is photochemically reactive and undergoes cyclization to afford a pink cyclic form on irradiation at 366 nm.  

Some new pyrrylfulgide derivatives have been studied as potential optical storage materials. The photochromic properties of (Z)-4-oxazolylfulgim-ide (Z)-l-benzyl-4-isopropylidene-3-[l-(2-aryl-5-methyloxazolyl)ethylidene]te-trahydrofuran-2,5-dione, a new class of fulgimide, have been examined.  

A patent application has described the synthesis and photochemical reactivity of the fulgimide derivatives (131). Fulgimides can be prepared by conversion of the fulgides (132) and (133). The resultant products shown photochromic properties. Some new derivatives of fulgimides have been reported with thieno[3,2-b]pyrrole fragments attached to the maleimide.  

The influence of chiral substituents attached to the trienes (274) on the cyclization of these molecules has been examined. Irradiation at 450 nm leads to diastereoisomeric pairs in the closed form. The outcome of the reaction is solvent dependent and one of the best results is obtained on irradiation at low temperature in toluene. Under these conditions the diastereoenantiomeric excess was 86.6%. 

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Fulgides and fulgimides - potentially useful for information storage in erasable optical disks ... 

Table 4.21. Quantum Yield of Photocyclization Reaction of Fulgides and Fulgimides in Solution and Polymer Matrix51 91...

Source Based on V, Deblauwe and G. Smets, Quantum yields of the photochromic reactions of heterocyclic fulgides and fulgimides, Makromol. Chem, 189, 2503-2512 (1988). 

J. Whittall, Fulgides and fulgimides— a promising class of photochromes for application, in Applied Photochromic Polymer System (C. B. McArdle, ed.), pp. 80-120, New York (1991). 

As with all photochromic polymers, the polymer matrix effect is very important in fulgides and fulgimides as the polymer free volume affects rate of photocoloration and photobleaching. For example, Bahajaj and Asiri recently reported that the rate of photochemical reactions of fulgide doped in a variety of polymer matrices decreased in the order polystyrene > poly(methyl methacrylate) > epoxy resin [37]. Polystyrene possesses a larger free volume than poly(methyl methacrylate) and epoxy resin... 

The interesting story of the photochromism of fulgides and fulgimides has continued with a report that the cyclization process in a series of fulgides occurs by mr excitation of one of the two largely independent chromophores in the molecule.824 The luminescence and photochromism of some azomethines885 and the isomeric forms of hydronaphthyl radicals 320 have been investigated, and the... 

Such 671-electrophotocyclization is commonly observed for a variety of 1-arylbuta-l,3-dienes and is also the basic process for the photochromism of fulgides and fulgimides. The mechanism of these reactions has been subjected to a theoretical investigation using PM3 semiempirical quantum chemistry and MECI Cl methods, and the results are reported to support the mechanism... 

Whittall, J., Fulgides and Fulgimides — A promising class of photochrome for appUcation, in Applied Photochromic Polymer Systems, McArdle, C.B., Ed., Blackie, Glasgow, 1992, chap. 3. 

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