Nitrogen Centered Radicals

在该项目中，由化学部的化学结构，动力学机制B计划资助，内布拉斯加大学林肯分校化学系的Andrzej Rajca教授正在开发适用于新的磁性，电子和光学技术开发的新型有机自由基。本研究的目标是设计、合成和表征具有不寻常的平行电子自旋排列和/或嵌入手性结构的高自旋自由基。 这些自由基的结构进行了优化，以提供具有导电性的单组分材料，用于动态核极化（DNP）核磁共振（NMR）光谱的顺磁剂，以及用于自旋电子学的有机自旋过滤器。由于拟议的研究活动涉及有机合成，各种物理/材料表征和计算，它们将为各级科学家提供获得广泛教育的机会。该小组也有能力为科学领域代表性不足的学生提供最高水平的教育和培训。这些非传统激进分子的设计和合成，随着复杂性和挑战性的增加而不断发展，为创造性思维和解决问题提供了绝佳的平台。非常规分子的合成与不寻常的合成方法有关。所提出的导电超鲁棒高自旋自由基提供了对交叉共轭π系统中的电子（或空穴）传输的更好的洞察，这通常被认为是对导电性有害的。这将有助于我们理解多个单占据近简并带的影响以及高自旋分子之间强反铁磁相互作用对电子输运的影响。所提出的磁性和热稳定的高自旋双自由基，优化分子荧光将提供荧光高自旋双自由基的第一个例子，在环境条件下，近100%的人口的三重基态。这些高自旋双自由基的优化高DNP增强可以推进DNP NMR光谱及其应用。对映体纯的双螺旋高自旋双自由基双阳离子和三自由基阳离子是有趣的新型分子，具有热鲁棒性，对映体纯的手性π-系统，和强顺磁性。所提出的双螺旋高自旋双自由基二价阳离子的手性性质的强度与[n]螺旋烯的手性性质的强度相当，因此，手性和强顺磁性的共存可能使独特的手性磁性为发现新的有机磁性提供了一个新的平台，该奖项反映了NSF的法定使命，并被认为是值得支持的，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。

In this project, funded by the Chemical Structure, Dynamics & Mechanisms B Program of the Chemistry Division, Professor Andrzej Rajca of the Department of Chemistry at University of Nebraska-Lincoln is developing novel organic radicals that are applicable to the development of new magnetic, electronic, and optical technology. The goal of this research is the design, synthesis, and characterization of high-spin radicals, possessing the unusual parallel electron spin alignment and/or embedded within chiral structures. Structures of these radicals are optimized to provide single-component materials with electrical conductivity, paramagnetic agents for dynamic nuclear polarization (DNP) nuclear magnetic resonance (NMR) spectroscopy, as well as organic spin filters for spintronics. As the proposed research activities involve organic synthesis, diverse physical/materials characterization, and computations, they will provide an opportunity to gain a broad education for scientists at all levels. This group is also well-positioned to provide the highest level of education and training for students underrepresented in science.The design and synthesis of these unconventional radicals, that are evolving with increasing complexity and challenge, provide excellent platforms for creative thinking and problem-solving. The syntheses of the unconventional molecules are of noteworthy interest related to the unusual synthetic methodology. The proposed conducting ultra-robust high-spin radicals provide better insight into electron (or hole) transport in cross-conjugated pi-systems, which are commonly known to be detrimental to the conductivity. They will enhance our understanding of the impact of multiple singly-occupied near-degenerate bands and strong antiferromagnetic interactions between the high-spin molecules that facilitate the electron transport. The proposed magnetically and thermally robust high-spin diradical that is optimized for molecular fluorescence would provide the first example of fluorescent high-spin diradical with near 100% population of the triplet ground state at ambient conditions. Those high-spin diradicals that are optimized for high DNP enhancements could advance the DNP NMR spectroscopy and its applications. The proposed enantiomerically pure double helical high-spin diradical dications and triradical cations are intriguing novel molecules with thermal robustness, enantiomerically pure chiral pi-system, and strong paramagnetic properties. The strength of chiroptical properties of the proposed double helical high-spin diradical dication is comparable to those of [n]helicenes, and thus, the coexistence of chirality and strong paramagnetism may render unique chiromagnetic properties that provide a novel platform for the discovery of new organic magneto-optic materials and efficient organic spin filters for spintronics.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.