Abstract: The norfloxacin is an effective and safe anti-infective with broad-spectrum, and can be taken orally ·Its ¹H spin-lattice relaxation times (T₁) were determined in the presence and absnce of some transintion metal ions such as Cr³⁺, Mn²⁺ and Fe³⁺.The experimental results showed that T₁ values appeared to vary regularly by the addition of these paramagnetic metal ions with unpaired electrons in the high spin state. The T₁ values of ¹H at different sites reduced variously m-ong which the T₁ values of 2-H and 5-H reduced most obviously. The structures of the complexes, bonded states and bonding quantity are discussed with respect to the relaxation times thus measured.

Key words: norfloxicin, NMRT₁, transition metal ion, Complex, Stereochemical structure