Nitrogen Centered Radicals

内布拉斯加大学林肯分校化学系的Andrzej Rajca教授在化学结构、动力学和机理B项目的资助下，正在开发一种新的有机自由基，这种自由基可以应用于新的磁性、电子和光学技术的发展。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。对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滤波器。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。这个群体也处于有利地位，可以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。这些非常规自由基的设计和合成，随着复杂性和挑战的增加而不断发展，为创造性思维和解决问题提供了极好的平台。非常规分子的合成与非常规的合成方法有关，值得注意。所提出的导电超鲁棒高自旋自由基为交叉共轭pi系统中的电子（或空穴）输运提供了更好的见解，这通常被认为是有害的电导率。它们将增强我们对多个单占据近简并带的影响和高自旋分子之间促进电子传递的强反铁磁相互作用的理解。本文提出的高自旋双自由基在磁性和热稳定性上都很好，并对分子荧光进行了优化，这将是在环境条件下具有接近100%三重态基态的荧光高自旋双自由基的第一个例子。这些高自旋双自由基被优化为高DNP增强，可以促进DNP核磁共振光谱及其应用。所提出的对映纯双螺旋高自旋双基阳离子和三基阳离子是具有热鲁棒性、对映纯手性pi体系和强顺磁性的新分子。所提出的双螺旋高自旋双基化的手性强度与[n]螺旋烯相当，因此，手性和强顺磁性的共存可能会产生独特的手性，为发现新的有机磁光材料和用于自旋电子学的高效有机自旋滤波器提供新的平台。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

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.