Effect of electric field on the microcosmic properties of cation compound containing 2,2,6,6-tetramethyl-1-piperidinyloxy and imidazole unit.

A theoretical study of the electric-field effect on the electronic structures and related properties of the cation compound containing 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and imidazole unit has been carried out, using the density functional theory (DFT) at the (U) B3LYP/6-31+G(d,p) level. The changes and regularities of geometric and electronic properties of the researched compound under electric field were revealed in detail. The results show the following: (1) Electric field has a very important effect on the orbital energy, dipole moment, natural population, and structure of the cation compound. Most of these properties are changed orderly with the increase of the electric-field intensity. (2) It is very interesting to find that in the present different electric-field intensities, the structure of cation compound after getting an electron becomes bis-radical form, that is, no mater in or out of electric-field, the cation compound will exist in a triplet state after getting an electron. (3) When getting an electron, the change of the cation structure mainly appears on the imizadole head, and when losing an electron, the change mainly appears on the TEMPO head. These theoretical results considering the electric-field effect for the cation compound help to explain the related experimental phenomena and further to direct the functional molecular design of this kind of compound.