A metal organic framework (MOF) engineered to contain in its scaffold rod‐like struts featuring ultrafastmolecularrotors showed extremely rapid 180 ° flip reorientation with rotational rates of 1011 Hz at 150 K. Crystal‐pore accessibility of the MOF allowed the CO2 molecules to enter the cavities and control the rotor spinning speed down to 105 Hz at 150 K. Rotor dynamics, as modulated by CO2 loading/unloading
Ionic Rotors. Preparation, Structure, and Dynamic Solid-State <sup>2</sup>D NMR Study of the 1,4-Diethynylbenzenebis(triphenylborate) Dianion
作者:James R. Gardinier、Perry J. Pellechia、Mark D. Smith
DOI:10.1021/ja053256j
日期:2005.9.1
The reaction between p-(LiC2)2C6H4 (generated in situ from butyllithium and dialkynylbenzene) and 2 equiv of BPh3 affords high yields of [Li(THF)4]2[p-(Ph3BC2)2C6H4], a heretofore missing member of the isoelectronic [p-(Ph3EC2)2C6H4] (E = groups 13-15 element) series. The central phenylene linker is free to rotate in the solid state, as determined by a variable-temperature solid-state 2D spin-echo NMR spectroscopic study. At room temperature, the rate of rotation is at least 20 times faster than that of its carbon-based analogue, presumably a result of Coulombic repulsions minimizing noncovalent interactions between rotating units in the borate salt.