Five complexes [Co3(Hpmad)6]·(4‐sb)2·(CH3COO)2·(H2O)2 (1), [Co3(Hpmad)6]·(3‐sb)2·(CH3COO)2·(H2O)0.5 (2), [Co(Hpmad)2(4‐sb)]n (3), [Co(Hpmad)2(3‐sb)]n (4) and {[Co(Hpmad)(SO4)(H2O)2]·H2O}n (5) [Hpmad is 2‐pyrimidineamidoxime, H2(4‐sb) is 4‐sulfobenzoic acid and H2(3‐sb) is 3‐sulfobenzoic acid], were prepared at room temperature. Complexes 1–5 were characterized by elemental analyses, single crystal X‐ray diffractions, powder X‐ray diffractions, infrared spectra, thermogravimetric analyses, fluorescence spectra and magnetic susceptibility measurements. Complexes 1 and 2 possess the linear trinuclear Co2+ structures. Complexes 3 and 4 exhibit similar one‐dimensional (1D) chains. Complex 5 comprises the 1D helical chain. The change of anion in cobalt salt from CH3COO− to Cl− to SO42− leads to the structural evolution from the linear trinuclear Co2+ structure to the 1D chain to the 1D helical chain. Complexes 1–5 exhibit the Hpmad‐based emissions. The magnetic properties of 1–5 were also investigated.