As　an　emerging　class　of　hybrid　complexes,　donor-acceptor　(D-A)　hybrid　heterostructures　with　advantages　of　both　photoactive　organic　and　inorganic　components　have　provided　an　excellent　platform　for　the　fabrication　of　multifunctional　photoactive　materials.　In　this　context,　we　have　demonstrated　three　novel　host.　guest　D-A　hybrid　heterostructures,{[Ln(BCEbpy)(H2O)(4)][Co-III(CN)(6)]center　dot　4H(2)O)(n)　(1　(Eu),　2　(Dy),　3　(Sm)),　based　on　the　anionic　Co(CN)(6)(3-)　and　cationic　coordination　layers　assembled　from　a　viologen　functionalized　tecton　and　Ln(NO)(3).　Due　to　the　introduction　of　an　electron　donor,　Co-III(CN)　6　3,　the　unique　hybrid　exhibits　a　highly　sensitive　and　reversible　photochromic　transformation　from　light-yellow　to　brown　upon　UV-Vis　irradiation.　More　interestingly,　accompanied　with　this　photochromic　process,　hybrid　1　simultaneously　possesses　a　photomodulated　fluorescence　behaviour.　In　addition,　hybrid　1　shows　high　sensitivity　and　selectivity　towards　Cr2O72-　anions　with　a　fairly　small　LOD　of　ca.　9.6　x　10(-6)　M.