Vibrational and electronic spectroscopy of diamondoid cations and their clusters

类金刚石是最近建立的一类新的稳定的、无应变的、刚性的脂肪族环烷烃，在分子纳米尺度上代表SP3杂化碳。由于其独特的和强烈可变的性质，它们是具有定制的机械、电子、光学、手性、化学和药物性质的新型纳米材料的有前途的构建块。这些性质的变化是通过化学功能化、掺杂、杂化形成和溶剂化实现的，使它们在材料和聚合物科学、分子电子学、生物医学科学和化学合成中得到应用。此外，类钻石和纳米钻石在星际环境中大量存在，它们携带着相当大一部分宇宙碳。在许多方面，这种新型的基于sp3的碳材料是对研究得很好的sp2形式石墨烯和富勒烯的补充，诺贝尔物理学奖(2010年)和化学奖(1996年)分别获得了这两个奖项。尽管钻石状阳离子很重要，但它们的光谱性质基本上是未知的。然而，要在分子水平上深入了解它们的几何、电子、光学和(生物)化学性质的详细知识。为此，在这个更新项目中，我们继续我们成功和开创性的初步努力，使用最先进的激光光谱(红外和光学)、质谱学、光电子能谱和量子化学方法表征简单的钻石状阳离子、它们的衍生物和溶剂化簇合物的几何、电子、光学、化学和药物性质。需要实验室光谱与天文数据进行比较，以提高我们对它们在星际介质中产生的了解，并潜在地确定它们是长期已知但尚未指定的漫射星际波段和未确定的红外发射波段的载体。此外，对衍生物的研究还允许对它们的光学和化学性质进行调制。金刚烷类阳离子与非极性和极性配体的微溶剂化揭示了这些高活性中间体的中心性质，提供了分子水平的反应机理，对于开发稳定的金刚烷及其杂化化合物的有机合成和选择性官能化的新路线非常重要。最后，类金刚石离子的电子光谱将为开发和测试量子化学方法提供基本的实验基准，以可靠地计算其具有挑战性的激发态谱，这些激发态谱往往因振动耦合而变得复杂。

Diamondoids are a recently established new class of stable, strain-free, rigid, aliphatic cycloalkanes, representing sp3-hybridized carbon at the molecular nanometer scale. With their unique and strongly variable properties, they are promising building blocks for new nanomaterials with tailored mechanical, electronic, optical, chiral, chemical, and pharmaceutical properties. Variation of these properties is achieved by chemical functionalization, doping, hybrid formation, and solvation, making them candidates for applications in materials and polymer science, molecular electronics, biomedical sciences, and chemical synthesis. Furthermore, diamondoids and nanodiamonds are abundant in interstellar environments, carrying a substantial fraction of cosmic carbon. In many aspects, this novel sp3-based carbon material is complementary to the well-studied sp2 forms graphene and fullerenes, for which Nobel prizes were awarded in physics (2010) and in chemistry (1996). Despite the importance of diamondoid cations, their spectroscopic properties are essentially unknown. However, detailed knowledge of their geometric, electronic, optical, and (bio)chemical properties is required for a deep understanding at the molecular level. To this end, in this renewal project we continue our successful and pioneering initial efforts to characterize the geometric, electronic, optical, chemical, and pharmaceutical properties of simple diamondoid cations, their derivatives and solvated clusters using state-of-the-art laser spectroscopy (IR and optical), mass spectrometry, photoelectron spectroscopy, and quantum chemical methods. Laboratory spectra are required for comparison with astronomical data to improve our understanding of their production in interstellar media and to potentially identify them as carriers of the long known but yet unassigned diffuse interstellar bands and the unidentified infrared emission bands. In addition, the study of derivatives allows for the modulation of their optical and chemical properties. Microsolvation of diamondoid cations with nonpolar and polar ligands sheds light on central properties of these highly reactive intermediates, providing molecular-level insight into reaction mechanisms important for developing novel routes in the organic synthesis and selective functionalization of stable diamondoids and their hybrids. Finally, electronic spectra of diamondoid cations will provide fundamental experimental benchmarks for developing and testing quantum chemical approaches for the reliable calculation of their challenging excited state spectra, which are often complicated by vibronic coupling.