Abstract: | With the coordination geometry of DyIII being relatively fixed, oxygen and sulfur atoms were used to replace one porphyrin pyrrole nitrogen atom of sandwich complex (Bu)4N]DyIII(Pc)(TBPP)] Pc = dianion of phthalocyanine, TBPP = 5,10,15,20-tetrakis(4-tert-butyl)phenyl]porphyrin]. The energy barrier of the compounds was enhanced three times, with the order of DyIII(Pc)(STBPP) > DyIII(Pc)(OTBPP) > (Bu)4N]DyIII(Pc)(TBPP)] STBPP = monoanion of 5,10,15,20-(4-tert-butyl)phenyl-21-thiaporphyrin, OTBPP = monoanion of 5,10,15,20-(4-tert-butyl)phenyl-21-oxaporphyrin]. Theoretical calculations offer reasonable explanations of such a significant enhancement. The energy barrier of 194 K for DyIII(Pc)(STBPP) represents the highest one among all the bis(tetrapyrrole) dysprosium SMMs, providing a strategy to rationally enhance the anisotropy and energy barrier via atom replacement. |