Acidichromism of indolinospirooxazines in isopropanol

1,3,3-tnmethyl-spiro[mdolino-2,3’-[2H]naphtho[2,1-b] [1,4]oxazine(SP1) and 1,3,3-trimen-thyl-9-methoxy-spiro[indolino2,3’-[2H]naphtho[2,1-b] [ 1,4]oxazine] (SP2) react with hydrochloric acid to form the complex SP HCl in isopropanol solution at room temperature The absorption maxima of these complexes are 440 and 463 nm respectively In acidic media,the opening form of spirooxazine can react with hydrochloric acid to form the complex PMC HCl via zwittenon form The absorption spectra of PMC HCl are obviously hypsochromic shifted compared with the reported spectra of the complex in neutral media In the mean time,the thermal stability of the complex is increased.The first order kinetics for the decoloration process of the acidichromic product of the opening form was determined and the lifetimes of these products are 180 and 200 s,respectively.

Photochromic fulgides and spirooxazines: mechanism and substituent effect on photoreactions

Molecular design, synthesis and photochromic properties of spirooxazines and fulgides are described. In the case of fulgides, the change of the substituents may lead to different photochromic properties and different photoreactions of the kind of compounds. In photochromic process of pyrryl-substituted fulgides, the excited singlet state is the mam species, but the excited triplet state is also involved. However, no excited triplet state has been observed in cyclization of aryl-substituted fulgides. In the case of spirooxazines, the substituents at 2’-position have great effect on the formation of photoproduct and on the mechanism of photoreaction. The increase of steric hindrance of the 2’-position substituent gives rise to the decrease of the quantum yield for the formation of photochromic merocyanine (PMC) and the increase of the relative quantum yield for the charge separated twist intermediate (CT).

SYNTHESES OF PHOTOCHROMIC PIGMENTS

Photochromism is a phenomenon that a compound undergoes a reversible color change with the change of the wavelength of the irradiating light. Many photochromic compounds have been used in textiles as photochromic pigments.In this paper, some special techniques are used to prepare a photochromic compound of spirooxazines with an improved yield. Another photochromic spirooxazine with a sulfonate group which is soluble in water is also successfully synthesized. Tests are also conducted to find that they both display good photochromism in proper states.

Crystal Structure and Photochromism in Paint of 1,3,3-Trimethyl-6'-dihydro-indolinyl- spiro[2,3'-[3H]-naphtho[2,1-b][1,4]]oxazine

The title compound 2 （C30H27N3O, Mr = 445.55） has been synthesized and its structure was determined by X-ray crystallography method. The crystal is of monoclinic, space group P21/c with a = 17.520（15）, b = 8.640（7）, c = 15.439（13） A, β = 98.642（14）°, V = 2310（3） 3, Dc = 1.281 g/cm^3, μ = 0.780 mm^-1, F（000） = 944, Z = 4, the final R = 0.0671 and wR = 0.1790 for 1952 observed reflections with Ⅰ 〉 2σ（Ⅰ）. X-ray analysis revealed that the interatomic distance of C（20）O（1） is 1.464（4） , longer than that of the normal C-O bond （1.41～1.43 A） in the six-membered heterocycle, but this kind of change coincides with other spiro compounds. The six-membered heterocycle containing spiro Csp3-O is nonplanar. The UV-vis spectra of the title compound in polymer films showed that it exhibits excellent photochromic property.

The effect of substituents and polymer media on photochromism kinetics of indolinospironaphthoxazine

The effect of substituents in indoline moiety and polymer media on photochromism and thermal decay processes of spirooxazine (ASP) was investigated. The thermal decoloration rate was decreased with increasing steric hindrance of substituents in I-position of indoline moiety. The stability of the colored forms was improved when the hydrogen in the 5-position of indoline moiety was replaced with electron-donating groups and was decreased when substituted by electron-withdrawing groups. In addition, the stability of the colored forms was related to properties of polymer media. The thermal decay rate decreased with an increase in the polarity and rigidity of polymer media. The themal decay kinetics of the colored forms obeyed biexponential decay law.

Synthesis and Flash Photolysis Studies of 1,3,3,2'-tetramethyl-9'-methoxy Indolinospironaphthoxazine

A new spirooxazine,1,3,3,2′-tetramethy1-9′-methoxyspiro [-2H-indole-2,3′-[-3H] naphth[2,1-b] [-1,4′] oxazine] (Ⅰ) was synthesized.Its photochromic process was studied using nanosecond time-resolved absorption spectroscopy techniques.After irradiation of I with 248 nm laser pulse,a short-lived col-ored species with two absorption bands was observed.In cyclohexane the two bands appear at 470 nm and640 nm,while in acetonitrile at 460 nm and 670 nm.The kinetics for the decay of the colored species is first-order,and its lifetimes are 0.5 μs in cyclohexane and 1.3 μs in acetonitrile.From these results,this short-lived species is assumed to be an intramolecular charge-transfer (CT) intermediate instead of photomero-cyanines (PMC).No absorption band of PMC has been found.The phenomenoncan be interpreted by theproposed potential energy curve.

Synthesis and time-resolved absorption spectra of 1,3,3,5,2'-pentamethylspiro[indolinnaphthooxazine]

The title compound 1,3,3,5,2'-pentamethylspirooxazine (I) is synthesized and identified by 1R, 1H NMR and elemental analysis. The time-resolved transient absorption spectra of I are investigated by nanosecond laser flash photolysis. The photolysis of I in solution excited by 248 nm laser pulse results in two different colored species. One of them is a short-lived species (CT intermediate), which has two absorption maxima at 440 and 640 nm in acetonitrile, and 450 and 640 nm in cyclohexane. The corresponding lifetimes are 12 and 0.8 us, respectively. The absorption spectra of CT intermediate are not influenced by solvent polarity. This fact indicates that the structure of CT is between the zwitterionic and quinoidal ones. The much longer lifetime of CT in acetonitrile than in cyclohexane is due to the electron donating effect of methyl in position 5 of indolino ring. The long-lived colored species (>>80 us) proves a planar photomerocyanine (PMC) structure, whose absorption spectra in acetonitrile and cyclohexane show the absorption maxima at 640 and 600nm, respectively.

Synthesis and Photochromism of Novel Spiro（indoline-2,3＆#39;-naphtho [2,1-b] [1,4] oxazine）

A series of novel spirooxazine（SPO） derivatives containing nitrogen heterocycles was synthesized and characterized by 1H NMR spectra, Fourier transform infrared（FTIR） spectra, mass spectra（MS） and elemental analy- sis, and their photochromic behaviors were fully investigated in solvents and polymer media. In solvents, they dis- played excellent photochromism properties such as high photochromic response and fast thermal bleaching rate. Es- pecially, compounds 1 and 4 exhibited strong fluorescence intensities in dichloromethane solution. It was additionally found that compound 4 showed high fatigue resistence in poly（methyl methacrylate）（PMMA） film, and the thermal decay curves were fitted with biexponential function in PMMA film.