The　formation　of　metal-organic　frameworks　(MOFs)　under　given　reaction　conditions　depends　on　various　factors　including　reaction　duration,　temperature,　used　solvent,　system　pH,　and　others.　Among　them,　the　reaction　duration　is　relatively　less　investigated.　In　this　work,　based　on　a　Cu(ii)-MOF　system,　the　reaction　duration　was　found　to　play　an　important　role　in　directing　the　formation　of　two　different　products,　(NH2(CH3)(2))[Cu-12(DDPN)(6)(H2O)(10)Cl]　(BUT-301)　on　shorter　reaction　time　and　(NH2(CH3)(2))(2)[Cu(DDPN)]　(BUT-302)　on　longer　reaction　time,　when　CuCl2　reacted　with　3,5-di(3,5-dicarboxylphenyl)nitrobenzene　(H4DDPN)　in　a　DMA/MeOH　mixed　solvent　at　120　degrees　C.　With　increasing　the　reaction　duration,　BUT-301　can　transform　into　BUT-302.　Both　MOFs　have　three-dimensional　(3D)　framework　structures.　BUT-301　is　constructed　from　paddle-wheel　Cu-2(COO)(4)　units　and　DDPN4-　ligands　as　four-connected　linkers,　while　BUT-302　is　assembled　from　mononuclear　Cu(ii)　centers　connecting　the　ligands　as　also　four-connected　linkers　but　in　a　monodentate　coordination　fashion.　N-2　adsorption　confirmed　that　both　MOFs　are　porous　materials　with　the　Brunauer-Emmett-Teller　(BET)　surface　areas　of　1953　and　561　m(2)　g(-1),　respectively.　Interestingly,　both　BUT-301　and　-302　show　selective　adsorption　properties　of　C3H4　over　C3H6.　The　C3H4/C3H6　adsorption　selectivities　were　calculated　to　be　1.9　and　4.4　at　0.1　bar　and　298　K　by　the　ideal　adsorbed　solution　theory　(IAST)　for　a　1:99　C3H4/C3H6　mixture,　respectively.