Two carboxyl-substituted iron(II) grids, one protonated, [Fe-4(HL)(4)](BF4)(4)center dot 4MeCN center dot AcOEt (1), and the other deprotonated, [Fe-4(L)(4)]center dot DMSO center dot EtOH (2), where H2L = 4-{4,5-bis [6-(3,5-dimethylpyrazol-1-y1)pyrid-2-yl]-1H-imidazol-2-yl}benzoic acid, were synthesized. Single-crystal X-ray structure analyses reveal that both complexes have ate tranuclear [2 x 2] grid structure. 1 formed one-dimensional chains through intermolecular hydrogen bonds between the carboxylic acid units of neighboring grids, while 2 formed two-dimensional layers stabilized by pi-pi-stacking interactions. 1 showed spin transition between the 3HS-1LS and 1.5HS-2.5LS states around 200 K, while 2 showed spin-crossover between the 4LS and 2LS-2HS states above 300 K. A modified indium-tin oxide (ITO) electrode was fabricated by soaking the ITO in a solution of 1. The resultant electrode showed reversible redox waves attributed to the original redox processes of iron(II)/iron(III).