By　using　squarates　as　coordination　building　units,　six　new　complexes　formulated　as　[Mg(C4O4)(H2O)2]n　(1),　[Pr2(C4O4)2(OA)(H2O)4]n　(2),　[Eu2(C4O4)3(H2O)8]n　(3)　[Cd2(C4O4)2(bpdo)(H2O)4]n　(4),　[Cd(C4HO4)2(H2O)4]·(MV)2·(C4O4)2　(5),　and　[Cd(C4HO4)2(H2O)4]·(EV)·(C4HO4)2　(6),　where　(C4O4)2-　=　squarate,　OA　=　oxalic　acid,　MV　=　methyl　viologen,　EV　=　ethyl　viologen,　and　bpdo　=　4,4′-dipyrdiyl-N,N′-dioxide,　have　been　synthesized　under　hydro/solvothermal　conditions.　They　present　structural　dimensions　from　3-D　networks　(1,　2),　2-D　layers　(3,　4)　to　0-D　clusters　(5,　6)　based　on　the　versatile　bridged　modes　of　squarates　and　the　introduction　of　second　ligands.　In　particular,　5　and　6　are　the　first　examples　incorporating　squarates　(electronic-rich　species)　with　viologens　(electronic-poor　species)　in　one　lattice.　Consequently,　they　exhibit　not　only　photocurrent　responses　but　also　reversible　thermochromism,　which　will　be　beneficial　for　the　design　of　multi-functional　materials.　©　2017　the　Partner　Organisations.