• Bulletin of the Korean Chemical Society
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• v.22 no.3
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• pp.271-275
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• 2001

We investigated H-type molecular aggregation in a simply spin-coated amorphous homopolymer film of polymethacrylate containing push-pull azobenzene moieties. It was found that the aggregate formation was strongly influenced by thermal treatment an d that the aggregate created in the polymer film could be easily disrupted by irradiation of a linearly polarized light. In the first writing cycle of aggregated polymer film, photo-induced birefringence showed a steep increase to the highest value followed by a gradual decrease to the certain asymptotic value under longer irradiation of a linearly polarized light. This unique behavior could be attributed to the cooperative motion and the disruption of the aggregated molecules under continuous irradiation of light.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3740-3744
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• 2012

We synthesized three different derivatives of bis-spiropyran using simple organic reactions with high yields. BSP1, a derivative of bis-spiropyran having a connection at the position 6' and BSP2, a derivative of bis-spiropyran having a connection at the position 5 and BSP3, a derivative of bis-spiropyran containing a dithienylethene group between two spiropyran moieties were synthesized. The optical properties of BSPs were characterized. UV-Vis spectra showed that BSPs exhibit reversible photo-isomerization and the efficiency of photo-isomerization is highly dependent on the position of nitro group. BSPs having nitro group at para position of hydroxy group showed the higher efficiency of photo-isomerization that the one having nitro group at ortho position. The optical microscope images obtained under ultraviolet or visible light exposure demonstrated that the formation of nanorods can be reversibly controlled by optical signal.