9-hydroxyphenalenone derivatives

The nature of the phase transitions and proton-deuteron dynamics in the crystals of 9-hydroxyphenalenone derivatives have been investigated by means of solid state NMR spectroscopy. It was found that the antiferroelectric ordering of deuterons along the hydrogen bonds in 5-methyl-9-deuterioxyphenalenone and 5-bromo-9-deuterioxyphenalenone occurs below the phase transition temperatures at 44 K and 34 K, respectively. The microscopic origin of the incommensurate modulation in 5-bromo-9-deuterioxyphenalenone below 34 K was attributed to slight rotational displacements, which are fixed at commensurate angles below the lock-in transition at 22 K. 

In order to suppress the dynamic disorder of the parent compound in the crystal, the 5-methyl and 5-bromo derivatives of 9-hydroxyphenalenone [8], [41] were prepared. X-Ray crystallographic analysis revealed that the molecular arrangement is completely ordered and that the symmetry around... 

For 9-hydroxyphenalenone 3 and its derivatives, the freezing temperature of the tautomeric equilibrium (Scheme 5.1) is below — 100°C, a temperature at which it is hardly possible to get the necessary chemical shift differences (Av (Hz)) of the exchanging nuclei in solid-state CP-MAS NMR spectra. A new method has been published to determine the rate constants for the spin relaxation... 

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