Photoresponsive Vinyl Azide Crystals

本课题由化学系化学结构、动力学机制B项目资助，安娜D.辛辛那提大学化学系的Gudmundsdottir正在研究“光动力”晶体背后的基础科学。 这些都是不寻常的物质，它们暴露在光线下会移动。当被照亮时，光动力晶体可以扭曲，弯曲，跳跃，爬行或粉碎。 这种行为具有开发新设备的潜力，在这些设备中，光被转换为运动，例如致动器和传感器。该项目的跨学科性质，它连接光化学和材料科学，为学生提供了多样化的教育培训机会。通过这项研究，学生准备作为未来的科学家谁可以解决社会面临的技术挑战。 高中和大学本科生将从科学领域代表性不足的群体中招募，在Gudmundsdottir实验室进行研究。Gudmundsdottir研究小组研究了结晶乙烯基叠氮衍生物的光动力学行为，这些衍生物在光照下分解为三重态乙烯基氮烯和分子N2。对于每种乙烯基叠氮化物衍生物，晶格内的氮释放模式是不同的。一些晶体在破裂之前容忍晶格内大的N2气泡的积累，而另一些晶体在光照下立即释放N2。 在这项研究中，确定了控制晶体内N2分子释放的结构因素。作为这项研究的一部分，这些化合物的固态光反应性进行了研究，通过进行激光闪光光解的纳米晶体。这些研究旨在表征晶体内形成的瞬态，并确定这些瞬态的固态动力学。 X射线晶体学和光产物鉴定是这项研究的关键要素。固态反应机制得到量子化学计算的支持。 总的来说，这些数据可以阐明详细的固态反应机制，并解释晶格如何控制乙烯基叠氮衍生物的反应性和光动力学行为。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

In this project, funded by the Chemical Structure, Dynamics & Mechanisms B Program of the Chemistry Division, Professor Anna D. Gudmundsdottir of the Department of Chemistry at the University of Cincinnati is studying the fundamental science behind "photodynamic" crystals. These are unusual substances which move as they are exposed to light. When illuminated, photodynamic crystals can twist, bend, leap, crawl or shatter. This behavior holds the potential for development of new devices in which light is converted into motion, such as actuators and sensors. The interdisciplinary nature of this project, which connects photochemistry and materials science, provides diverse educational training opportunities for students. Through this research, students are prepared as future scientists who can address the technical challenges facing society. Both high school and college undergraduate students will be recruited from groups underrepresented in science to carry out research in the Gudmundsdottir laboratory. Students will also be provided with educational activities that focus on their professional development.The Gudmundsdottir research group investigates photodynamic behavior of crystalline vinyl azide derivatives which, upon light exposure, dissociate to triplet vinylnitrenes and molecular N2. The mode of nitrogen release within the crystal lattice is distinctive for each vinyl azide derivative. Some crystals tolerate a build-up of large N2 bubbles within the lattice before cracking, whereas others release N2 immediately with light exposure. In this research, structural factors which control the release of N2 molecules within the crystal are identified. As part of this research, solid-state photoreactivity of these compounds is investigated by performing laser flash photolysis of nanocrystals. These studies are designed to characterize the transients formed within the crystals and determine the solid-state kinetics of these transients. X-ray crystallography and photoproduct identification are critical elements of this study. Solid-state reaction mechanisms are supported by quantum chemical calculations. Collectively, these data make it possible to elucidate detailed solid-state reaction mechanisms and explain how the crystal lattice controls both the reactivity and the photodynamic behavior of vinyl azide derivatives.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.