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项目资助下，研究了与新型磁性材料和光学技术相关的稳定有机多自由基。有了稳定的有机多自由基，轻质、柔软的有机磁体就可以被开发出来，应用于可穿戴电子产品。稳定的有机多自由基还可以辅助磁共振成像造影剂的研制，在医学诊断中得到广泛应用。这个跨学科的研究项目有能力为各级科学家提供最高水平的培训和教育，包括那些目前在科学领域代表性不足的科学家。该项目的具体目标是高自旋氮（胺基）中心二、三和多自由基，螺旋折叠高自旋碳中心多自由基，螺旋和双螺旋寡硫吩基自由基。高自旋胺基自由基来源于一种基于环形交叉共轭结构的分子设计，这种结构促进了电子自旋密度在铁磁耦合器中的离域。这些自由基预计在室温下具有很长的半衰期，这将允许隔离和/或热坚固性，允许在真空下升华以制备薄膜。螺旋和双螺旋低硫噻吩基自由基是一种具有手性体系和顺磁性的新颖分子。顺磁性与螺旋或双螺旋pi系统相结合，由于手性和离域电子自旋的结合，可能会呈现出独特的性质，为开发具有固有强手性的新型顺磁性材料提供了一条途径，这可能有助于发现新的有机磁光材料和器件。所提出的自由基是用现代有机合成方法制备的，并通过电子自旋共振光谱、超导量子干涉装置磁强计和计算进行了表征。

In this project funded by the Chemical Structure, Dynamic & Mechanism B Program of the Chemistry Division, Professor Andrzej Rajca of the Department of Chemistry at the University of Nebraska-Lincoln investigates stable organic polyradicals that are relevant to novel magnetic materials and optical technology. With stable organic polyradicals, lightweight, soft organic magnets, which have applications in wearable electronics, can be developed. Stable organic polyradicals can also assist the development of contrast agents for magnetic resonance imaging, which is widely used in medical diagnosis. This interdisciplinary research project is well positioned to provide the highest level of the training and education of scientists at all levels, including those currently underrepresented in science. The specific objectives of this project are high-spin nitrogen (aminyl) centered di-, tri- and polyradicals, helically folded high-spin carbon-centered polyradicals, helical and double helical oligothiophene-based radicals. The high-spin aminyl radicals derive from a molecular design based upon annelated, cross-conjugated structures that facilitate delocalization of electron spin density into the ferromagnetic coupler. These radicals are expected to possess a long half-life at room temperature that would permit isolation and/or thermal robustness permitting sublimation under vacuum to prepare thin films. The helical and double helical oligothiophene-based radicals are intriguing novel molecules with a combination of chiral pi-systems and paramagnetism. Paramagnetism associated with helical or double helical pi-system may render unique properties due to the combination of chirality and delocalized electronic spin, providing an avenue for development of novel paramagnetic materials with inherently strong chiral properties that could facilitate discovery of new organic magneto-optic materials and devices. The proposed radicals are being prepared by modern organic synthetic methodologies and characterized by electron spin resonance spectroscopy, superconducting quantum interference device magnetometry, as well as computations.