Photoresponsive Molecules and Materials - Controlling Chemistry and Biochemistry, Sensing and Imaging

该提案描述了将如何开发对光做出反应并随后执行重要功能的分子和纳米材料。这些项目利用光来可逆地改变分子结构，从而改变分子或材料的光学、电子和机械特性。项目实例包括（1）控制化学和生物化学反应性，（2）改变聚合物材料的性能，（3）检测分析物的存在或环境中的变化，（4）控制光学成像，以及（5）提供新的方法从设计纳米颗粒表面释放分子。可能受到影响的应用领域包括催化和化学加工、自愈聚合物、药物输送、生物成像以及检测和跟踪。 结构-功能关系的可逆控制是中心主题，可以通过使用“分子开关”来实现-分子通过以可预测的方式可逆地改变其结构来响应不同类型的光。分子光开关的重点一直放在可用于控制光电性质（吸收，发射，折射率）的系统上。分子光开关的一个开发较少的用途是它们如何调节化学和生物化学反应性，考虑到这种发展对化学合成，传感和监视，聚合物和生物化学的影响，这是令人惊讶的。 该提案描述了二芳基乙烯和螺吡喃结构在受到光刺激时如何改变它们的形状。由于分子的形状决定了它如何与其他分子反应或相互作用，因此该计划中开发的系统将被检查其催化工业相关反应，影响聚合物力学，抑制酶，作为传递载体和检测器以及调节开关成像的能力。 光的传输也是该计划的一个重要方面，将利用新的方法来产生引发有机反应所需的光。可以用有机光响应分子进行表面修饰的设计师纳米颗粒将是这方面成功的关键。我们将利用金属纳米颗粒吸收低能量光并将其转化为热量，可用于驱动化学反应。由于热量集中在纳米颗粒的表面，因此可以在不破坏环境的情况下诱导高度选择性的反应。这在细胞系统中特别重要，因为它克服了在敏感环境中使用高度破坏性的紫外线的问题，以便通过使用“远程控制”方法进行重要的化学反应。

This proposal describes how molecular and nanomaterials that respond to light and subsequently perform important functions ‘on-command’ will be developed. The projects use light to reversibly change molecular structure and consequently optical, electronic and mechanical properties of molecules or materials. Project examples include (1) controlling chemical and biochemical reactivity, (2) modifying the performance of polymeric materials, (3) detecting the presence of analytes or changes in the environment, (4) controlling optical imaging, and (5) providing novel means to release molecules from the surface of designer nanoparticles. Application areas that will be potentially impacted include catalysis and chemical processing, self-healing polymers, drug-delivery, bio-imaging, and detection and tracking. Reversible control over structure-function relationships is the central theme and can be accomplished by using ‘molecular switches’ - molecules that respond to different types of light by reversibly changing their structures in a predictable manner. The emphasis in molecular photoswitching has been on systems that can be used to control optoelectronic properties (absorption, emission, refractive index). A much less developed use for molecular photoswitches is how they can regulate chemical and biochemical reactivity, which is surprising considering the impact that this development would have on chemical synthesis, sensing and surveillance, polymers, and biochemistry. This proposal describes how diarylethene and spiropyran architectures change their shape when stimulated with light. Because the shape of a molecule dictates how it reacts or interacts with others, the systems developed in the program will be examined for their ability to catalyze industrially relevant reactions, effect polymer mechanics, inhibit enzymes, act as delivery vehicles and detectors, and regulate on-off imaging. The delivery of light is also an important aspect of the program and new methods to generate the light needed to trigger organic reactions will be utilized. Designer nanoparticles that can be surface decorated with organic photoresponsive molecules will be central to the success of this aspect. We will take advantage of metal nanoparticles that absorb low-energy light and convert it into heat, which can be used to drive chemical reactions. Because the heat is localized to the surface of the nanoparticles, highly selective reactions can be induced without damaging the environment. This is especially important in cellular systems because it overcomes the problem of using highly damaging UV light in sensitive environments in order to carry out important chemical reactions, by using ‘remote-control’ methods.