Magnetic characterization of one-dimensional systems composed of nitronylnitroxide radicals as studied by ESR and susceptibility measurements

We synthesized a novel organic radical 3,4-dichlorophenyl nitronyl nitroxid e and characterized magnetic properties in the solid state. An X-ray crysta l structure analysis revealed that this molecule formed one-dimensional reg ular chains in the crystal. Temperature dependence of magnetic susceptibili ty was reproduced by the antiferromagnetic regular chain model with an exch ange interaction J/k(B) = -8.0 K which is consistent with the crystal struc ture. The radical crystal is an example of the regular spin chain in the or ganic systems that exhibits the largest exchange interaction. Single-crysta l cw-ESR exhibited a temperature-dependent shift of g-value. The physical o rigin of the g-shift is discussed by comparing the observed data with theor ies describing the short range order effect in antiferromagnetic spin chain s. The possibility of demagnetizing field effect on the g-shift in the para magnetic crystal is also referred.