Reaction Dynamics and Applications in Patterning of Bisthienylcyclopentene-Based Photochromic Switches

Abstract

The structural and optical properties of the gel-forming photochromic switch 1,2-bis(2’-methyl-5’-{{((R) phenylethyl)amino}carbonyl}thienyl-3’-yl)cyclopentene are studied by means of the linear absorption and holographic grating techniques. The use of diffractive optics enables recording of holographic gratings with high long-term phase stability. The diffraction efficiency of the recorded holographic gratings approach values of 30% for low writing beam energies when diffusion is the rate determining factor. At higher writing pulse energies the competition between the diffusion and photodecomposition processes causes lower diffraction efficiencies. At irradiation doses above 10 mJ the spatial profile of the recorded gratings is strongly influenced by saturation effects. Because of the well-determined grating profile the holographic grating technique is potentially applicable for the quantitative characterisation of the diffusion process in photochromic gels.

Light‐Driven Dynamic Pattern Formation

“…These observations prompted us to investigate whether it would be possible to generate spatially confined gel objects embedded in a solution. The formation of such objects, by irradiation through an optical mask or by holographic imaging,10 requires that self‐assembly followed by immobilization in the gel state takes place faster than diffusion of molecules of 2 to nonilluminated regions. To the best of our knowledge, no artificial molecular systems are yet known that can be reversibly assembled, on command, into spatially confined macroscopic objects.…”

“…A solution of 1 (1.5 m M ) in toluene contained in a 1‐mm cell was irradiated with crossed UV beams ( λ ≈330 nm)10 at room temperature which resulted in the formation of transparent red‐colored gel patterns that resist gravitational flow, whereas the nonirradiated surroundings remained in the liquid state. UV irradiation of a solution of 1 with a nonuniform optical field results in the localized photochemical conversion to 2 , which self‐assembles to form a gel before diffusion of 2 to the nonirradiated areas can take place.…”