Crocker Reece D, Pace Domenic P, Zhang Bolong, Lyons Demelza J M, Bhadbhade Mohan M, Wong Wallace W H, Mai Binh Khanh, Nguyen Thanh Vinh
School of Chemistry, University of New South Wales, Sydney, NSW 2052, Australia.
Bio21 Institute and School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia.
J Am Chem Soc. 2021 Dec 8;143(48):20384-20394. doi: 10.1021/jacs.1c10038. Epub 2021 Nov 22.
The alternating physical properties, especially melting points, of α,ω-disubstituted -alkanes and their parent -alkanes had been known since Baeyer's report in 1877. There is, however, no general and comprehensive explanation for such a phenomenon. Herein, we report the synthesis and examination of a series of novel ω-phenyl -alkyl tropylium tetrafluoroborates, which also display alternation in their physicochemical characters. Despite being organic salts, the compounds with odd numbers of carbons in the alkyl bridge exist as room temperature ionic liquids. In stark contrast to this, the analogues with even numbers of carbons in the linker are crystalline solids. These solid nonconjugated molecules exhibit curious photoluminescent properties, which can be attributed to their ability to form through-space charge-transfer complexes to cause crystallization-induced emission enhancement. Most notably, the compound with the highest photoluminescent quantum yield in this series showed an unusual arrangement of carbocationic dimer in the solid state. A combination of XRD analysis and calculations revealed interesting insights into these systems.
自1877年拜耳的报告以来，人们就已经知道α,ω-二取代烷烃及其母体烷烃的交替物理性质，尤其是熔点。然而，对于这种现象尚无普遍而全面的解释。在此，我们报告了一系列新型ω-苯基烷基四氟硼酸卓鎓盐的合成与研究，它们在物理化学性质上也表现出交替性。尽管是有机盐，但烷基桥中碳原子数为奇数的化合物在室温下以离子液体形式存在。与此形成鲜明对比的是，连接基中碳原子数为偶数的类似物是结晶固体。这些固态非共轭分子表现出奇特的光致发光性质，这可归因于它们形成空间电荷转移复合物以导致结晶诱导发光增强的能力。最值得注意的是，该系列中光致发光量子产率最高的化合物在固态下显示出碳正离子二聚体的不寻常排列。XRD分析和计算相结合，揭示了对这些体系的有趣见解。
