Photoisomerisation in single molecules of nitroprusside embedded in mesopores of xerogels |
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Authors: | Andrea Schuy Theo Woike Dominik Schaniel |
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Affiliation: | (1) I. Physikalisches Institut, Universit?t zu K?ln, Zülpicher Str. 77, 50937 K?ln, Germany |
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Abstract: | Photoswitchable hybrid materials are successfully prepared by embedding guanidinium nitroprussides (GuNP, (CN3H6)2[Fe(CN)5NO]) into mesopores of transparent xerogel monoliths. The such prepared hybrid materials exhibit a higher photostability than the corresponding GuNP solutions, whereby the chemical stability of the [Fe(CN)5NO]2−-anion in titania gel is nearly infinite. By irradiation with light in the blue-green spectral range one nitrosyl isomer is formed by a 180° rotation of the NO ligand changing the Fe–NO into a Fe–ON coordination (SI), which is detected by the shift of the ν(NO) stretching vibration from 1945 cm−1 (Fe–NO) to 1820 cm−1 (Fe–ON). Consequently there is enough space around the NO-ligand for such movement in xerogel mesopores. The embedding in silica xerogels increases the achievable population of the isomeric nitrosyl configuration to about 15% with respect to a single crystalline powder where only 9% are reached. |
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Keywords: | Optical material Photochromic Xerogel Linkage isomer Photoswitching Photochromic |
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