الفهرس 
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Abstract
In recent years, numerous applications of photochromic substances have been suggested, and some of these have entered commercial practice. Photochromic sunglasses, plastics incorporating a photochromic dye have also been used for aircraft windows and one method of optical storage is to use photochromics molecules that change colour on absorbing light in a suitable region.
The phenomena of photochromism and thermochromism in Schiff base series depend on the crystal structure of the compounds and the presence of the orthohydroxy azomethine group is considered an essential condition for both effects.
Poly [(2-hydroxy-1-naphthalenyl) methylene--methyl acrylic acid hydrazide, (2-hydroxy-1-naphthalenyl) methylene acetylhydrazine and (2-hydroxy-1-naphthalenyl) methylene stearoylhydrazine were prepared and characterized in terms of elemental analysis, infrared, ultraviolet and visible spectra as well as excitation, emission spectra. The irradiations on these compounds were studied both in solid state and in solution.
The electronic absorption spectra of poly [(2-hydroxy-1-naphthalenyl) methylene--methylacrylic acid hydrazide] and related monomer and stearoyl exist in solution in enolimne form, which is stabilized by intramolecular hydrogen bonding between the phenolic oxygen and azomethine nitrogen. While in case of hydroxylic solvent or proton acceptor solvent, these compounds can exist in the enolimine form in equilibrium with the mononegative anion.
These compounds in solid state exist in enolimine form beside some ketoamine tautomer.