UB1LYP hybrid density functional studies of the 2,2,6,6-tetramethyl-4-piperidone-oxyl (TEMPONE) hyperfine tensors

The UB1LYP hybrid density functional and Baroneʹs triple-ζ EPR-III basis sets are used to calculate the hyperfine tensor components of the TEMPONE spin label in its chair, boat and twisted forms at a moderate computational expense. Very good agreement between the computed 1H, 13C, 14N and 17O hyperfine tensor components and those determined by EPR, NMR and ENDOR spectroscopy is obtained provided the effects of the solvent, NO vibrational bending modes and twisting of the ring are taken into account.