Departamento de Química Orgánica I, Facultad de Química, Universidad del País Vasco and DIPC (Donostia International Physics Center), P. K. 1072, E-20018 San Sebastián-Donostia, Spain.
IKERBASQUE, Basque Foundation for Science, E-48009 Bilbao, Spain.
Inorg Chem. 2023 Mar 13;62(10):4097-4105. doi: 10.1021/acs.inorgchem.2c03884. Epub 2023 Feb 27.
In the context of materials science, six-membered phosphorus heterocycles are intriguing building blocks due to their tunable properties through phosphorus post-functionalization and their unique hyperconjugative effects arising from the phosphorus substituents that contribute to further tuning the optoelectronic properties of the system. Seeking for the discovery of improved materials, the latter features have triggered an astonishing evolution of molecular architectures based on phosphorus heterocycles. Theoretical calculations showed that the hyperconjugation causes a reduction in the S-S gap, which strongly depends on the nature of both the P-substituent and the π-conjugated core, but where are the limits? Outlining the hyperconjugative effects of six-membered phosphorus heterocycles would allow scientists to know how to design next-generation organophosphorus systems with enhanced properties. Herein, we discovered that, in cationic six-membered phosphorus heterocycles, an increase in the hyperconjugation does not affect the S-S gap anymore; i.e., quaternizing the phosphorus atoms leads to properties that go beyond those provoked by hyperconjugative effects. DFT calculations revealed that the latter is particularly marked in phosphaspiro derivatives. Our detailed investigations spotlight the potential of π-extended systems based on six-membered phosphorus spiroheterocycles for accessing properties beyond those achieved to date through hyperconjugative effects, thus laying the groundwork for new research possibilities toward improved organophosphorus systems.
在材料科学领域，六元磷杂环因其磷后功能化可调节的性质以及磷取代基产生的独特超共轭效应而成为引人关注的构建模块，这种超共轭效应有助于进一步调节体系的光电性能。为了寻找性能更好的材料，后者的特性引发了基于磷杂环的分子架构的惊人发展。理论计算表明，超共轭作用会导致 S-S 能隙减小，这强烈依赖于 P 取代基和π共轭核的性质，但这种影响有多大？概述六元磷杂环的超共轭效应将使科学家能够了解如何设计具有增强性能的下一代有机磷系统。在此，我们发现，在阳离子六元磷杂环中，超共轭作用的增加不再影响 S-S 能隙；也就是说，磷原子的季铵化导致的性质超出了超共轭效应所引起的性质。DFT 计算表明，在后一种情况下，磷螺环衍生物的超共轭效应尤为显著。我们的详细研究强调了基于六元磷螺杂环的π扩展体系在获得超出目前通过超共轭效应获得的性质方面的潜力，从而为改进有机磷系统的新研究可能性奠定了基础。
