Pandian Ramasamy P, Dang Vinh, Manoharan Periakaruppan T, Zweier Jay L, Kuppusamy Periannan
Center for Biomedical EPR Spectroscopy and Imaging, Department of Internal Medicine, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH 43210, USA.
J Magn Reson. 2006 Jul;181(1):154-61. doi: 10.1016/j.jmr.2006.04.004. Epub 2006 May 11.
Lithium octa-n-butoxy-naphthalocyanine (LiNc-BuO) is a stable free radical that can be detected by electron paramagnetic resonance (EPR) spectroscopy. Previously we have reported that microcrystals of LiNc-BuO exhibit a single sharp EPR peak, whose width varies linearly with the partial pressure of paramagnetic molecules such as oxygen and nitric oxide. In this report, we present the effect of nitrogen dioxide (NO2), which is also a paramagnetic molecule, on the EPR properties of LiNc-BuO. The gas-sensing property of LiNc-BuO is attributed to the open molecular framework of the crystal structure which is arranged with wide channels capable of accommodating large molecules such as NO2. The EPR linewidth of LiNc-BuO was highly sensitive to the partial pressure of NO2 in the gas mixture. The line-broadening was quick and reversible in the short-term for low concentration of NO2. However, the EPR signal intensity decreased with time of exposure, apparently due to a reaction of NO2 with LiNc-BuO crystals to give diamagnetic products. The results suggested that LiNc-BuO may be a useful probe for the determination of trace amounts of NO2 using EPR spectroscopy.
八正丁氧基萘酞菁锂（LiNc-BuO）是一种稳定的自由基，可通过电子顺磁共振（EPR）光谱检测。此前我们报道过，LiNc-BuO微晶呈现出一个尖锐的EPR峰，其宽度随氧和一氧化氮等顺磁性分子的分压呈线性变化。在本报告中，我们展示了同样作为顺磁性分子的二氧化氮（NO2）对LiNc-BuO的EPR性质的影响。LiNc-BuO的气敏特性归因于晶体结构的开放分子框架，该框架由能够容纳NO2等大分子的宽通道排列而成。LiNc-BuO的EPR线宽对混合气体中NO2的分压高度敏感。对于低浓度的NO2，在短期内线宽展宽迅速且可逆。然而，EPR信号强度随暴露时间下降，显然是由于NO2与LiNc-BuO晶体反应生成了抗磁性产物。结果表明，LiNc-BuO可能是一种利用EPR光谱测定痕量NO2的有用探针。
