Two newly synthesized Fe(III) based complexes, [Fe4L2(μ3-O)2(Cl)2(MeOH)4(H2O)4](ClO4)2.4H2O.MeOH (1) and [Fe2L3].4DMF (2) were isolated as solid crystalline form using the reaction of iron(III) perchlorate with the ligand H2L (H2L = 6,6’-((1E,1’E)-hydrazine-1,2-diylidenebis(methanylylidene))bis(2-methoxyphenol). (DMF= N,N-dimethylformamide, MeOH = methanol). Compound 1 was self-assembled in MeOH but when solvent was changed to DMF, compound 2 was harvested. Further, compound 1 was converted to compound 2 just by dissolving compound 1 in DMF. Sequential self-assembly and conversion of compound 1 to 2 were monitored by UV-Vis spectroscopy and ESI-Mass spectroscopy in solution phase. Single crystal X-ray analysis showed that compound 1 has μ3-oxo bridged tetranuclear structure whereas compound 2 has puckered di-nuclear structure. Magnetic studies indeed revealed frustrated magnetic spin for compound 1 whereas antiferromagnetic interaction was observed for compound 2. The spectrophotometrical investigation on...