摘要:

This paper deals with the investigation of the photodegradation of (2,2-(4,4′-dimethoxyphenyl)-5,6-dimethyl-[2H]-naphtho-[1,2-b]pyran in toluene solution and in polyurethane matrix. With the aim of proposing mechanisms for the photodegradation processes, a complete determination of the photoproducts' structures has been carried out using HPLC, GC/MS and direct introduction MS techniques. The different techniques allowed us to detect the production of well-known photoproducts but also the formation of new high molecular weight oxygenated derivatives. Our investigations also underline the detection of new photo-induced products that are produced by secondary oxidative pathway.

ISSN:1058-725X    

DOI:10.1080/10587250008023886

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Photochromic bisbenzothienylethene has two conformers, photo-reactive anti-parallel and inactive parallel ones. The cyclization quantum yield is dependent on the ratio of the two conformers. By the introduction of bulky substituents at 2-positions of the benzothiophene rings, the cyclization quantum yield increased along with the increase in the ratio of the anti-parallel conformer.

ISSN:1058-725X    

DOI:10.1080/10587250008023887

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We described two synthetic routes for preparation of new crown ether derivatives of polyenals, containing variable length of the conjugation chain.

ISSN:1058-725X    

DOI:10.1080/10587250008023888

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The optical properties of cis-1,2-dicyano- 1,2-bis(2,4,5-trimethyl-3-thienyl) ethene as a photochromic dye is studied. Vacuum evaporation has been used to prepare thin films for possible practical applications, especially optical information storage.

ISSN:1058-725X    

DOI:10.1080/10587250008023889

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Two novel 1,2-bis(1,3-dimethylindol-2-yl)cycloalkenes(2) were designed and synthesized by intramolecular coupling reaction using low-valance titanium as catalyst. Photochromic properties of these compounds were initially investigated. The results show that the thermal stability of colored form of2is much better than that of 1,2-bis(1-ethyl-2-methylindol-3-yl)cycloalkenes(4), and the absorption maximum of them is shorter than that of 1,2-bis(1-ethyl-2-methylindol-3-yl)cycloalkenes.

ISSN:1058-725X    

DOI:10.1080/10587250008023890

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A novel kind of photochromic compounds, the derivatives of 1-(3-Methylbenzo[b]thiophen-2-yl)-2-(2-methylindol-3-yl)cyclo-alkene was successfully synthesized. The absorption bands of the closed-forms of these compounds centered at 440 nm thus possessing the sensitivity within the wavelength range of InGaN blue laser.

ISSN:1058-725X    

DOI:10.1080/10587250008023891

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The synthesis and photochromism of clay-diarylethene (PyDE) hybrid materials have been investigated. The obtained hybrid materials efficiently exhibited photochromism, but its photochromic efficiency decreased when UV and visible irradiation was repeated. This photochromic degradation could be improved by coadsorbing the cationic surfactant molecules with the PyDE molecules.

ISSN:1058-725X    

DOI:10.1080/10587250008023892

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Photochromic cyclization reaction efficiency and fluorescence of colloidal solutions, amorphous films, and polymer cast films of two dithienylethenes were studied. Photochromic cyclization reaction efficiency of colloidal solution of cis- 1,2-dicyano- 1,2-dithienylethene (1) was as high as that of hexane solution of1. Amorphous films of1also showed high efficiency. On the other hand, neither colloidal solution nor polycrystal of 2,3-bis(2,4,5-trimethyl-3-thienyl)maleic anhydride (2) was photochromic; only amorphous films of2were colored very slightly by UV irradiation. While photochromic cyclization reaction efficiency of1depends little on the kind of polymer matrix, that of2depends significantly on the Tg (glass transition temperature) and polarity of polymer matrix. Long-wavelength fluorescence which can be assigned to the colored closed-ring form was observed for1in the solid states, though deeply colored hexane solution did not give any long-wavelength fluorescence.

ISSN:1058-725X    

DOI:10.1080/10587250008023893

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Transient absorption spectra of 1′,3′,3′-trimethyl-6-nitrospiro[2H-1-benzopyran-2,2′-(2H)-indole](6-nitro-BIPS) microcrystalline powder were measured by femtosecond diffuse reflectance spectroscopy and compared with those in the benzene solution and in a PMMA film. A very similar photochromic reaction occurs even in the crystal, although the structure of the generated photo-colored form in crystalline phase is not as planar as that of a stable form (trans-planar merocyanine) in solution. Photocoloration and the following thermal back reaction dynamics are considered in terms of free volume of the matrix and limited motion of the molecule.

ISSN:1058-725X    

DOI:10.1080/10587250008023894

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Definite clathrate crystals of deoxycholic acid and its amide and alcohol derivatives as host molecules withN-salicylideneaniline as a guest molecule were prepared to investigate their photochromic properties. The photocoloration study was done by irradiating the crystal powder with 365 nm light; the thermal fading reaction of the photocolored species was followed by reflectance spectrophotometry at 303 K. From the sharp difference in the first-order rate constants of the thermal bleaching of the photochromes, it was found that the thermal unimolecular motion of photo-colored species was strongly influenced by the neighboring environments in the crystal state.

ISSN:1058-725X    

DOI:10.1080/10587250008023895

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor