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Solid‐State Dynamics and High‐Pressure Studies of a Supramolecular Spiral Gear
Author(s) -
Fornasari Luca,
Olejniczak Anna,
Rossi Federica,
d'Agostino Simone,
Chierotti Michele R.,
Gobetto Roberto,
Katrusiak Andrzej,
Braga Dario
Publication year - 2020
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201905744
Subject(s) - supramolecular chemistry , chemistry , crystallography , octane , spiral (railway) , molecule , nuclear magnetic resonance spectroscopy , thermodynamics , stereochemistry , crystal structure , physics , organic chemistry , mathematics , mathematical analysis
The structures and solid‐state dynamics of the supramolecular salts of the general formula [(12‐crown‐4) 2 ⋅ DABCOH 2 ](X) 2 (where DABCO=1,4‐diazabicyclo[2.2.2]octane, X=BF 4 , ClO 4 ) have been investigated as a function of temperature (from 100 to 360 K) and pressure (up to 3.4 GPa), through the combination of variable‐temperature and variable‐pressure XRD techniques and variable‐temperature solid‐state NMR spectroscopy. The two salts are isomorphous and crystallize in the enantiomeric space groups P 3 2 2 1 and P 3 1 2 1 . All building blocks composing the supramolecular complex display dynamic processes at ambient temperature and pressure. It has been demonstrated that the motion of the crown ethers is maintained on lowering the temperature (down to 100 K) or on increasing the pressure (up to 1.5 GPa) thanks to the correlation between neighboring molecules, which mesh and rotate in a concerted manner similar to spiral gears. Above 1.55 GPa, a collapse‐type transition to a lower‐symmetry ordered structure, not attainable at a temperature of 100 K, takes place, proving, thus, that the pressure acts as the means to couple and decouple the gears. The relationship between temperature and pressure effects on molecular motion in the solid state has also been discussed.