Sterical effects of encapsulation on some cobalt complexes built up in zeolite Y - A Mossbauer emission spectroscopy study

Mossbauer emission spectroscopy revealed effects of encapsulation on 2,2'-b ipyridine and 1,10-phenantroline complexes of Co-57(2+) synthesized in the supercages of zeolite Y. The tris coordinated phenantroline complex, unexpe ctedly, did not form in the supercage due to the blocking effect of the cag e walls. The spectra of the tris bipyridine complex did not show the high s pin state of the nucleogenic iron(II) complex. This is attributed to the ve ry short lifetime of this state destabilized by the misfit to the volume of the zeolite cage. The relaxation rate was estimated and compared with life times measured on the complex embedded in other matrices.