Photoswitching of basicity
Photoswitching of basicity
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DOI：
10.1002/anie.200802050
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发表时间：
2008-01-01
影响因子：
16.6
通讯作者：
Hecht, Stefan
中科院分区：
文献类型：
--
作者：
Peters, Maike V.;Stoll, Ragnar S.;Hecht, Stefan
The ability to control function at the molecular level by means of external stimuli is one of the key requirements for the development of “smart” devices and materials. In particular, the use of light as a trigger offers distinct advantages, as it is a noninvasive stimulus that can be manipulated precisely by modern optics to provide exquisite temporal and spatial resolution. The functional response of the molecular system to light is mediated by photoactive moieties: either photolabile protecting groups, which lead to irreversible activation (caging), or photochromic moieties, which enable reversible activation and deactivation (switching).[1] While a variety of molecular properties have successfully been rendered photoswitchable in recent years,[2] examples in which catalysis—perhaps the most attractive function from a chemist s standpoint—has been reversibly photoregulated are scarce.[3] Such systems are particularly attractive, as they would in principle enable the translation of a light stimulus into a chemical signal, which would be amplified further in the subsequent catalytic cycle. The resulting high efficiency of the overall process, which can be controlled reversibly by light, should lead to various new applications in chemical surface patterning [4, 5] and sensing.Recently, we have become interested in developing photoswitchable catalysts that control catalytic activity on the basis of steric and electronic factors. Initial designs based on metalloporphyrins failed owing to inhibition of the photochromic reactivity through energy transfer to the active site of the catalyst.[6] We therefore turned our attention to photoswitchable bases,[7, 8] in which the catalytically active site is optically silent. Herein, we present the first photoswitchable organic bases, the reactivity of which is controlled by reversible steric shielding (Figure 1), and demonstrate the significant structure and reactivity differences associated with the two switching states.
