Refractive -index changes of thin films of photo-reactive α-, β-, and γ-cyclodextrin derivatives upon photo-irradiation

We have synthesized cyclodextrin (CD) derivatives with pendant norbornadiene (CD-NBD), with pendant azobenzene (CD-AZ), with pendant cinnamate (CD-CI), with pendant chalcone (CD-CH), and with pendant anthracene (CD-AT). In thin films of these CD derivatives under UV irradiation, photochemical isomerization of CD-NBD and CD-AZ, and photochemical dimerization of CD-CI, CD-CH, and CD-AT proceeded smoothly. The photochemical reactions were accompanied with large refractive index changes (ΔnD's) of 0.023–0.030 (CD-NBD), 0.015–0.023 (CD-AZ), 0.041–0.048 (CD-CI), 0.057–0.071 (CD-CH), and 0.062–0.083 (CD-AT), as determined by ellipsometry.