Department of Chemistry & Biochemistry and Material Science Institute, University of Oregon, Eugene, Oregon 97403, United States.
Knight Campus for Accelerating Scientific Impact, University of Oregon, Eugene, Oregon 97403, United States.
J Am Chem Soc. 2020 May 13;142(19):8763-8775. doi: 10.1021/jacs.0c01117. Epub 2020 Apr 30.
Porous molecular materials combine benefits such as convenient processability and the possibility for atom-precise structural fine-tuning which makes them remarkable candidates for specialty applications in the areas of gas separation, catalysis, and sensing. In order to realize the full potential of these materials and guide future molecular design, knowledge of the transition from molecular properties into materials behavior is essential. In this work, the class of compounds termed cycloparaphenylenes (CPPs)-shape-persistent macrocycles with built-in cavities and radially oriented π-systems-was selected as a conceptually simple class of intrinsically porous nanocarbons to serve as a platform for studying the transition from analyte sorption properties of small aggregates to those of bulk materials. In our detailed investigation, two series of CPPs were probed: previously reported hoop-shaped []CPPs and a novel family of all-phenylene figure-8 shaped (lemniscal) bismacrocycles, termed spiro[,]CPPs. A series of nanocarbons with different macrocycle sizes and heteroatom content have been prepared by atom-precise organic synthetic methods, and their structural, photophysical, and electronic attributes were disclosed. Detailed experimental studies (X-ray crystallography, gas sorption, and quartz-crystal microbalance measurements) and quantum chemical calculations provided ample evidence for the importance of the solid-state arrangement on the porosity and analyte uptake ability of intrinsically porous molecular nanocarbons. We demonstrate that this molecular design principle, i.e., incorporation of sterically demanding spiro junctions into the backbone of nanohoops, enables the manipulation of solid-state morphology without significantly changing the nature and size of the macrocyclic cavities. As a result, the novel spiro[,]CPPs showed a remarkable performance as high affinity material for vapor analyte sensing.
多孔分子材料结合了诸多优点，例如便于加工和原子精度的结构微调的可能性，这使得它们成为气体分离、催化和传感等专业应用的杰出候选材料。为了充分发挥这些材料的潜力并指导未来的分子设计，了解从分子性质到材料行为的转变是必不可少的。在这项工作中，选择了一类被称为环方苯（CPP）的化合物-具有内置空腔和径向取向π-体系的形状稳定大环-作为一类概念简单的本征多孔纳米碳的平台，用于研究从小聚集体的分析物吸附性质到块状材料的转变。在我们的详细研究中，研究了两类 CPP：以前报道的环型[]CPP 和一类新型全苯环型（lemniscal）双大环，称为螺环[,]CPP。通过原子精确的有机合成方法制备了一系列具有不同大环尺寸和杂原子含量的纳米碳，并揭示了它们的结构、光物理和电子属性。详细的实验研究（X 射线晶体学、气体吸附和石英晶体微天平测量）和量子化学计算为固体排列对本征多孔分子纳米碳的孔隙率和分析物吸收能力的重要性提供了充分的证据。我们证明了这种分子设计原则，即将空间位阻螺环接头引入纳米环的骨架中，能够在不显著改变大环空腔的性质和尺寸的情况下操纵固态形态。结果，新型螺环[,]CPP 作为蒸气分析物传感的高亲和力材料表现出显著的性能。
