Spirooxazine Derivatives

Tamaki et al.17 reported that chelation of the colored forms of spirooxazines with divalent metals induced considerable shifts of the absorption spectra and significant retardation of decoloration in the dark. 

A spironaphthoxazine derivative incorporating a monoaza-12-crown-4 entity at the 5 -position has been prepared by Kimura el al.19 It is a light-resistant, cation-complexable photochromic compound. 

Guglielmetti20 reported the synthesis of spironaphthoxazines (compound 24) containing one thiophene entity which are precursors for the preparation of new molecular materials by electrochemical polymerization or copolymerization. 

Guglielmetti et al.21 also reported the synthesis of a series of thiophenes (e.g., 25) and terthiophenes (e.g., 26) substituted with spironaphthoxazine photochromic groups. It has been shown that electropolymerization of the thiophene group in 25 that occurs at 1.7 V [vs. saturated calomel electrode (SCE)] is blocked by the 

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Indolines, benzoxazole, and benzothiazole are possible as 2-methylene heterocycles. The number of known spirooxazine derivatives is much less than for the spiropyrans. This may be partly due to lack of many substituted o-nitrosonaphthols and partly due to lack of sufficient stability of spiro-oxazines. The structures of parent spirooxazines and the Xmax of their photomerocyanine forms are listed in Table 5. The Xmax of the colored forms of compounds 41-43 are not described in the literature. 

Kwak and Hurditch8 patented the family of indolino spirooxazines derived from 5-nitroso-6-hydroxyquinoline. This family, the spiropyridobenzoxazines, in general possesses greater sensitivities (that is, rates of activation) and equilibrium responses (Table 2.6). For example, spiropyridobenzoxazine 11 has a sensitivity of 0.56 (A0 >/min) and an equilibrium response of 0.42 (AOD) versus a sensitivity of 0.44 and an equilibrium response of 0.22 for the corresponding spironaphthoxazine. 

The spirooxazines derived from hydroxynitrosodibenzofurans have been disclosed by Yamamoto and Taniguchi.13 These photochromic compounds are interesting because their colored forms have two absorption bands in the visible range. For instance, compound 17 had absorption bands at 460 and 632 nm in methyl alcohol after UV irradiation. 

Resonance-enhanced coherent anti-Stokes Raman spectroscopy (CARS) has proven to be a useful technique for investigating the molecular structures of transient species.33 In nonpolar and polar solvents, CARS spectra of spirooxazine derivatives indicated the existence of two similar isomeric species. 

Step 3 spirooxazine derivatives of the invention have been prepared (4). 

As already noted, Schneider and co-workers were the first to report nanosecond time-resolved Raman spectra of spirooxazine derivatives (including the spironaphthoxazine), using resonance CARS.18 Two years later, the same group... 

Spirooxazine is an aza analogue of spiropyran in which the carbon atom at 3-position is replaced by a nitrogen atom. Historically, the photo-chromic phenomenon of spiroindolinooxazine derivatives was found after discovery of photochromic spiroindolinobenzopyran.72... 

The commercially available spirooxazines are based on the spiroindolinonaphthoxazines (1.11) ring structure. The synthetic route to this ring system involves the reaction of a l-hydroxy-2-nitoso bearing aromatic ring with a 2-aUcylidene heterocycle, such as Fischer s base (1.6 R = H). The naphthoxazines are the derivatives of choice... 

The medicinal use of the photochromic oxazine 379 was discussed in the previous section. The principle of photochromism was shown in Scheme 3, Section 8.06.5.1. Photochromic spirooxazines 101, 116, and 297 that have appeared in this chapter and their various substituted derivatives have been patented as photochromic materials <2003WO42195> and used as photochromic dyes in a microsphere-based sensor <2005USP19954>. The compound 299 is also used as photochromic material <2005S1876>. More detailed information about the applications of spirooxazines can be found in a review <2002RCR893>. The phenoxazine 380 has also been patented for use in optics <2005SUA2246491>. 

Oda18 investigated photostabilization by amphoteric counterions such as zinc salts of l-hydroxy-2-naphthoic acid and its derivatives. They were very effective in stabilizing the colored forms of spirooxazines (see Figure 2.3). 

Under controlled photolytic conditions, the rearranged oxidized product 273 was isolated from acetonitrile solution, and its structure was confirmed by X-ray analysis (Figure 19). Extensive photolysis led eventually to formation of di- and trimethyloxindoles, 13 and 14, a quinolone derivative, 265, and, in the case of spirooxazines, naphthoxazole 268. In the case of the two spiropyrans included in the study, 2-hydroxyl-l-naphthaldehyde and 5-nitrovanillin were also formed. It is... 

Semiempirical MO studies were also reported by other research groups.23 36 1 Recently, a systematic comparison of the various computational techniques for predicting the geometry and electronic spectra of spiropyrans and spirooxazines has been published.42 The validity of various semiempirical methods has been checked. This may provide a useful aid for practical uses of semiempirical methods.42 Molecular dynamics (MD) has also found use for these series of derivatives.43 5... 

It is relevant to cite here two more examples of the application of molecular calculations to spiropyran derivatives. First, in a study of the relationship between photochromism and second-order nonlinear optical (NLO) properties in spiropyran- and spirooxazine-doped polymer films, dipole moments, polarizabilities, and hyperpolarizabilities were estimated by the MNDO method.46 Second, the relative stabilities of the radical anions as well as their spin density distributions for a spiroindolinic series were calculated by an ab initio method in a combined electron paramagnetic resonance (EPR)/electrochemistry study.47... 

The Zv - complex of the merocyanine system (57) releases the zinc when it is irradiated with visible light and this results in the formation of the colourless closed spiropyranindoline (58, R = H). When the irradiation is stopped the Zn " complex reforms but this does not happen with the nitro derivative (58, R = NO2) in which it is thought that the nitro group stabilises the phenoxide ion in the open form. Other workers have also studied the complexation of spiropyran based merocyanines with transition and rare earth metal ions. An investigation of the influence of Lewis acids (hexa-fluoropropanol, trifluoroethanol and 2-fluoroethanol) on the stability of the coloured form of spiropyran and spirooxazines has been reported. Protonation of the open system produces a form that is photochemically inert and the behaviour of these acids is markedly different from that of acetic acid with such systems. 

Topics which have formed the subjects of reviews this year include photoinduced organic synthesis, photoisomerisations involving super-cyclophanes, regioselec-tive and stereoselective [2+2] photocycloadditions, position- and stereoselective photocyclisation, the photochemistry of indoles, five-membered heterocyclic compounds of the indigo group, pyrazoles and isothiazoles, and heterocyclic N-oxides, photochromic reactions of naphthopyran derivatives, photodegradation reactions of photochromic spirooxazines and 2H-chromenes, ° and chiral photo-chromic compounds. ... 

Spironaphthoxazine with a crown ether, 8, also shows photochromic behavior that is sensitive to the type of alkali and alkaline earth metal ions [14]. Other derivatives of spiropyran and spirooxazine, 9-12, which can chelate metal ions were synthesized, and the effects of complexation on their photochromic behavior have been investigated [15-17]. 

Photochromism of Spiropyrans Photoprocesses of Spiropyran-Derived Merocyanines Photoprocesses of Spiropyran Complexes with Metal Ions Photoprocesses of Spirooxazines... 

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