Photoresponsive Vinyl Azide Crystals

在这个由化学系化学结构、动力学和机理B项目资助的项目中，辛辛那提大学化学系的Anna D.Gudmundsdottir教授正在研究“光动力学”晶体背后的基础科学。这些都是不寻常的物质，当它们暴露在光中时会移动。当被照亮时，光动力晶体可以扭曲、弯曲、跳跃、爬行或破碎。这一行为为开发将光转化为运动的新设备提供了潜力，例如致动器和传感器。该项目的跨学科性质，连接了光化学和材料科学，为学生提供了多样化的教育培训机会。通过这项研究，学生们做好了成为未来科学家的准备，他们可以应对社会面临的技术挑战。高中生和大学本科生都将从科学界代表性不足的群体中招募，在Gudmundsdottir实验室进行研究。Gudmundsdottir研究小组研究结晶叠氮乙烯基衍生物的光动力学行为，这些衍生物在光照下会分解为三重态乙烯基氮和分子氮。每种乙烯基叠氮衍生物在晶格内的氮释放方式是不同的。一些晶体在破裂前可以容忍晶格中大的氮气气泡的积聚，而另一些晶体则在光照下立即释放出氮气。在这项研究中，确定了控制晶体内氮气分子释放的结构因素。作为这项研究的一部分，通过对纳米晶体进行激光闪光光解来研究这些化合物的固态光反应性。这些研究旨在表征晶体内形成的瞬变，并确定这些瞬变的固态动力学。X射线结晶学和光产物鉴定是这项研究的关键要素。量子化学计算支持固相反应机理。总而言之，这些数据使阐明详细的固态反应机理成为可能，并解释了晶格如何控制叠氮乙烯基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，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.