β-Hydroquinone xenon clathrate

Clathrate Structure Determination by Combining Crystal Structure Prediction with Computational and Experimental 129Xe NMR Spectroscopy

“…Based on these comparisons, likely crystal structures were proposed for the two clathrates. The proposed structures strongly resemble a previously known β‐hydroquinone xenon clathrate and have similar (12) hydrogen bonding motifs …”

“…The exceptional sensitivity of the 129 Xe chemical shift tensort oi ts local environmenta llows comparisons between observed andc alculated NMR chemical shift parameters that have been used to directly confirm or reject hypothetical clathrate structures.B ased on these comparisons, likely crystal structures were proposed for the two clathrates. The proposed structures strongly resemble ap reviously known b-hydroquinone xenon clathrate [6] and have similar R 6 6 (12) hydrogen bonding motifs. [84] The unusual o-fluorophenol 129 Xe NMR powder spectrum, with its negative CSA, wasi nitially thought to suggest as tructural motif different from the known and commonR 6 6 (12) hydrogen-bonded double sandwich.…”

“…The 129 Xe NMR spectrumo fo-fluorophenol shows negative CSA (Figure 2), Dd = À47.5 ppm, in contrast to all previously known solid-state 129 Xe NMRp owder patterns of phenol clathrates for which positive CSA is observed. [5][6][7][8][9][10] Changes in the sign of the CSA can be observed in ag roup of porousc hannel-like dipeptides, [80] where CSA changes from positive to negative with increasing xenon gas pressure,a nd therefore with pronounced Xe-Xe interactions playing ag reater role. No changes of the NMR spectrum of o-fluorophenol clathrate have been observed when repeating the experiment with samples at different pressures.…”

“…[2] Kazankin et al [3,4] reported that xenon clathrates can be formed froms everalm onosubstituted phenol compounds. With the exception of phenol, [5] hydroquinone, [5][6][7][8] p-cresol, [9] and p-fluorophenol, [10] Xe clathrates have not been described in the Englishl iterature and have remained relatively unknown in the West. The crystal structures of o-a nd m-fluorophenol xenon clathrates have, to our knowledge,n ever previously been determined.…”

Impact of confinement in multimolecular inclusion compounds of melamine and cyanuric acid

“…Clathrates are the most well-known multimolecular inclusion compounds found in the crystal state, being hydroquinone clathrates the most representative ones. It has been shown that hydroquinone can form these structures with several molecules and atomic species, like Xe, 4 hydrochloric acid, 5 carbon dioxide, 6 methanol and acetonitrile. 7 When clathrates are formed, a special arrangement of the multimolecular host is only stabilized due to the presence of the guest.…”