Iron(III)-tetra-o-ureaphenylporphyrinosilica obtained by a sol-gel process: a sutdy of EPR, surface area and catalytic activity - Biazzotto, Juliana Cristina; Vidoto, Ednalva Aparecida; Nascimento, Otaciro Rangel; Iamamoto, Yassuko; Serra, Osvaldo Antonio (International Symposium on Non-Crystalline Solids in Brazil, 2001)