Fulgide photochromic dyes

Figure 40.6 Structures and processes involved in the photochromism of the different photo-chromic dyes (diarylethenes, fulgides, azobenzenes, spiropyrans, spirooxazines, and naphtho-pyrans). The colors of the different states of the photochromic dyes are showed.

Allinson, H. and Gleeson, H.F., Physical properties of mixtures of low molar mass nematic liquid crystals with photochromic fulgide guest dyes, Liq. Crystals, 14,1469,1993. 

Several inks111 112 have been developed for paints and labels of security masks. Furyl fulgide was spun into fibers and woven into a fabric that was used to manufacture photochromic labels. In 1995, the Color Change Corporation (U.S.) exhibited several different color photochromic fabrics as commercial products at the third international symposium on the chemistry of functional dyes. 

R. Matsushima and S. Inoue, Structural and medium effects on the photochromic properties of sulfur-containing heterocyclic fulgides, in Chemistry of Functional Dyes (Z. Yoshida and Y. Shirota, eds.), Vol. 2, pp. 411-416, Mita Press, Tokyo (1993). 

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. ... 

Scheme 11.7 Photochromism of P-type dyes fulgide 11.41 and diaiylethene 11.42.

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