摘要:

New photochromic amorphous molecules containing core of triphenylamine and three branches of azobenzene were obtained in good yields by Pd-catalyzed amination. High glass temperature (Tg) above 100°C of these molecules was because of many triphenylamine units and high molecular weight. The stable amorphous films of these molecules could be easily prepared by spin-coated method. The photoinduced and thermal isomerization were observed in the amorphous films and the solutions. The size of the core had no clear effect on rates and activation energy values (Ea) of the cis→trans thermal isomerization in solution.

ISSN:1058-725X    

DOI:10.1080/10587250008023906

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

LB-films of an amphiphile containing diphenyldiacetylene moieties as chromophore have been prepared. Compared to the solution the LB-films show a different intensity ratio between the two diacetylene bands in the UV/Vis spectrum due to the dense packing of the chromophores. Irradiation with polarized light at 360 nm causes an angle dependent increase in the absorbance in the π-band region, which previously has been interpreted to be due to a photoreorientation process. However, a decrease of the π′-band in the UV/Vis spectra and the C≡C vibration band in the grazing angle reflectance IR-spectra indicate a photoreaction of the chromophores, which nature remains elusive. The increase in absorbance in the π-band region is conjectured to be to partial reversal of the intensity ratio changes due to a less dense packing of intact chromophores. From experiments, in which the irradiated LB-film is dissolved, the amount of reacted chromophores can be estimated to less than 20%.

ISSN:1058-725X    

DOI:10.1080/10587250008023907

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The in-plane orientation of a polysilane film on photochromic monolayer was controlled by irradiation with linearly polarized visible light. The polymer backbone was aligned in the perpendicular direction to the polarization plane of actinic light. In this photoprocess, the orientational order could be controlled by the light exposure dose.

ISSN:1058-725X    

DOI:10.1080/10587250008023908

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Xantheno[1′, 9′ : 4, 5, 6]benzo[1, 2, 3-kl]N-(1-dodecyl-2-pyridynium)-acridine iodide (2a) was synthesized from 1, 5-dichloroanthraquinone in six steps. The polarized UV-VIS spectra of the LB film of (2a) on CaF2were compared with the transition moments of (2a) calculated by semi-empirical molecular orbital method to discuss the orientation of (2a) in the LB film. The plane of the skeleton structure of the polycondensed aromatic ring of (2a) on CaF2in the LB film was rather oblique, not parallel to the CaF2surface.

ISSN:1058-725X    

DOI:10.1080/10587250008023909

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Photochemical reactions of an amphiphilic spiropyran (SP) have been investigated in single-layer LB films. The SP LB films were prepared from a pure water subphase at 30°C. When these LB films were irradiated with UV light at room temperature, SP was converted into photomerocyanine (PMC), followed by the formation of J-aggregate of PMC. In situ AFM observations revealed the presence of large circular domains with diameters of 10–20 μm and height of 4–5 nm before irradiation. Irregularly-shaped structures were evident in the center of most of the domains. On irradiation with UV light, dendritic structures spread radially from the irregularly-shaped structures and developed within the domains. The morphological change was not observed in the domains without the irregularly-shaped structures.

ISSN:1058-725X    

DOI:10.1080/10587250008023910

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

We have designed and synthesized 1,2-bis[6-(1-oxyl-3-oxide-4,4,5,5-tetramethylimidazolin-2-yl)-2-methylbenzo[b]-thiophen-3-yl]hexafluorocyclopentene which shows photo-switching of intramolecular magnetic interaction by incorporating two nitronyl nitroxide into diarylethene photochromic spin coupler.

ISSN:1058-725X    

DOI:10.1080/10587250008023911

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A large first-order magnetic phase transition in an organic radical, 1,3,5-trithia-2,4,6-triazap-entalenyl is described, that occurs with a wide thermal hysteresis loop over the temperature range from 230 to 305 K. The high-temperature phase is paramagnetic, while the low-temperature phase is diamagnetic. The results reported here on room-temperature magnetic molecular bistability may have applications in thermal sensors, switching units and information storage media, based on organic radical crystals.

ISSN:1058-725X    

DOI:10.1080/10587250008023912

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A couple of spin systems with photo-responsive property have been developed, i. e., norbor-nadiene and spiropyran derivatives carrying TEMPO-substituent and their light-induced structural changes to the corresponding quadricyclane or merocyanine derivatives have been investigated together with the changes of their properties in solution as well as in the solid state.

ISSN:1058-725X    

DOI:10.1080/10587250008023913

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Lately, a number of studies have been made on photo-induced cooperative phenomena from both theoretical and experimental viewpoints. These photo-effects can be named as a photo-induced phase transition (PIPT) and PIPT materials are attractive and potential candidates of photo-memory with high sensitivity. We focus on spin-crossover complexes as a typical example of the PIPT and report exotic characteristics of it.

ISSN:1058-725X    

DOI:10.1080/10587250008023914

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The radiation sensitivity of photochromic dithienylethenes was studied with the aim of developing a new reusable color film dosimeter. Upon γ-irradiation, polystyrene films containing 1,2-bis(2,5-dimethyl-3-thienyl)perfluorocyclopentene1and 1,2-bis(2-methyl-5-phenyl-3-thienyl)perfluorocyclopentene2turned red and blue, respectively. The red and blue colors disappeared by visible-light irradiation and the films could be reused. In both films the absorption intensities of the colors linearly increased with the absorbed dose. From the color change it was possible to estimate the radiation dose.

ISSN:1058-725X    

DOI:10.1080/10587250008023915

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor