Nitrogen Centered Radicals

在这项由化学系化学结构、动力学和机理B计划资助的项目中，内布拉斯加州大学林肯分校化学系的Andrzej Rajca教授正在开发适用于开发新的磁性、电子和光学技术的新型有机自由基。这项研究的目标是设计、合成和表征具有不寻常的平行电子自旋排列和/或嵌入在手性结构中的高自旋自由基。这些自由基的结构经过优化，可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)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、不同的物理/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。这一群体也处于有利地位，可以为在科学领域未被充分代表的学生提供最高水平的教育和培训。这些非传统部首的设计和合成，随着日益复杂和挑战的发展，为创造性思维和解决问题提供了极好的平台。非传统分子的合成与不同寻常的合成方法有关，引起了人们的注意。所提出的导电超强的高自旋自由基提供了更好的洞察电子(或空穴)在交叉共轭的pi体系中的输运，这通常被认为是有害于导电性的。它们将加深我们对多个单占据的近简并带和高自旋分子之间强烈的反铁磁相互作用的影响的理解，这些作用促进了电子的传输。所提出的磁性和热稳定性强的高自旋双自由基是分子荧光的最佳化，它将提供第一个在环境条件下具有近100%三重基态布居的荧光高自旋双自由基。那些为高DNP增强而优化的高自旋双自由基可以推动DNP核磁共振谱及其应用的发展。所提出的对映体纯的双螺旋高自旋二自由基和三自由基阳离子是具有热稳定性、对映体纯的手性pi体系和强大的顺磁性的有趣的新型分子。所提议的双螺旋高自旋双自由基正离子的手性性质的强度可与[n]螺旋烯的性质相媲美，因此，手性和强顺磁性的共存可能产生独特的手性磁性，为发现新的有机磁光材料和高效的有机自旋滤光器提供新的平台。该奖项反映了NSF的法定使命，并通过使用基金会的智力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.