Raman scattering and FT-IR spectroscopic studies on dithienylethene switches—towards non-destructive optical readout
作者:Jaap J. D. de Jong、Wesley R. Browne、Martin Walko、Linda N. Lucas、Lindsay J. Barrett、John J. McGarvey、Jan H. van Esch、Ben L. Feringa
DOI:10.1039/b603914f
日期:——
The non-destructive readout of photochromic memory materials based on the dithienylethene unit both by IR spectroscopy and Raman scattering is explored. A representative series of C5-substituted thienyl hexahydro- and hexafluoro-cyclopentene based photochromes was investigated to explore the effect and potential usefulness of substitution for the development of multicomponent memory materials. The effect of the deposition method on the photochemistry of solid materials containing photochromic dithienylcyclopentene switches was also explored. Photoconversion in the solid state to the closed form was found to be low when starting from the open form, but, in contrast, ring opening to the open state from the closed form was found to be complete. The effect was found to be due to inner filter rather than conformational phenomena. Characteristic vibrational bands for the central dithienyl core are assigned and a comparison made of the vibrational spectroscopic properties of the perhydro- and perfluoro switches. The data enable the determination of the photoconversion achievable in the solid state as well as some assessment of the influence of the deposition method on the photoconversion. The potential of Raman spectroscopy as a method of achieving non-destructive optical readout is demonstrated through the large differences in absolute Raman scattering intensity between the open and closed states, when monitored at wavelengths which do not result in photochemical ring opening.
探索了基于二噻二烯单元的光变记忆材料的非破坏性读出,采用红外光谱和拉曼散射。研究了一系列典型的C5取代的噻吩六氢和六氟环戊烯基光变材料,以探讨取代效应及其在多组分记忆材料开发中的潜在应用。还研究了沉积方法对含有光变二噻二烯环戊烯开关固态材料光化学的影响。发现从开态转化为闭态的光转化率较低,而从闭态转化为开态的环开过程则是完全的。此现象被认为是由于内过滤效应而非构象现象。为中央的二噻二烯核心分配了特征振动带,并对氢化和氟化开关的振动光谱性质进行了比较。这些数据使得能够确定固态下可实现的光转化率,以及对沉积方法对光转化影响的某种评估。通过在不导致光化学环开过程的波长下监测开闭态之间绝对拉曼散射强度的巨大差异,证明了拉曼光谱作为实现非破坏性光学读出的潜力。