selectively observed with short contact times (ca. 50 μs) without interference from other 13C signals in the molecule. Variable-temperature CPMAS 13C NMR studies with a crystalline o-xylene solvate of biphenylene rotor 2 suggested a 2-fold flipping process in the fast exchange regime, even at temperatures as low as 199 K (−74 °C). Indirect support for this was obtained by studies carried out with a disordered
的4,4'-双(3,3,3-三-样品d 5 -phenylpropynyl)
联苯2,9,10-双(3,3,3-三- d 5 -phenylpropynyl)
蒽3,1,4-双(3,3,3-三- d 5 -phenylpropynyl)
萘4,和4,4'-双(3,3,3-三- d 5 -phenylpropynyl)-
1,1'-联萘5制备通过3,3,3-三- Sonogashira偶联d 5 -phenylpropyne 7和合适的芳基
溴化物。对于得到的单晶的X射线衍射结构ø的二
甲苯包合物2和无溶剂的晶体3。通过改变接触时间的C
PMAS 13 C NMR实验对所有四个分子转子进行了表征,以确定是否可以选择性地增强和研究中心转子组的碳信号,而不会干扰或避免来自
氘化定子的信号重叠。 1 H} -13 C交叉极化方法。结果表明,可以在较短的接触时间(约50μs)内选择性观察到自然丰度旋转体组的13