Molecular motions in chloramphenicol studied by35Cl nuclear quadrupole and1H nuclear magnetic resonance spectroscopy

The35Cl nuclear quadrupole resonance (NQR) frequency (vQ), nuclear quadrupole spinlattice relaxation time (T1Q),1H nuclear magnetic resonance second moment (M2) and nuclear magnetic spin-lattice relaxation timeT 1) were measured for polycrystalline chloramphenicol (drug) as a function of temperature. Hindered rotation of the CHC12 group and the phenyl ring was detected, the relevant activation energies were determined. The rotations are discussed in detail.