Dynamic and redox active pillared bilayer open framework: Single-crystal-to-single-crystal transformations upon guest removal, guest exchange, and framework oxidation

A metal-organic pillared bilayer open framework having 3D channels, [Ni-2(C26H52N10)](3)[BTC](4)-6C(5)H(5)N.36H(2)O (BOF-1, 1), has been assembled from bismacrocyclic nickel(II) complex [Ni-2(C26H52N10)(Cl)4].H2O and sodium 1,3,5-benzenetricarboxylate (Na3BTC). The channels are occupied by pyricline and water guest molecules. When the single crystal of 1 was dried in air and then heated at 75degreesC for 1.5 h, respectively, [Ni-2(C26H52N10)]3[BTC](4).30H(2)O (1') and [Ni-2(C26H52N10)](3)[BTC](4).4H(2)O (2) resulted with retention of the single crystallinity. The X-ray structures reveal spongelike dynamic behavior of the bilayer framework that reduces the interlayer distance in response to the amount of guest molecules. Solid 2 differentiates various alcohols. When 1 was immersed in pyricline and benzene, guest molecules were exchanged with retention of the single-crystal nature to give rise to [Ni-2(C26H52N10)](3)[BTC](4).20pyridine-6H2O (3) and [Ni-2(C26H52N10)](3)[BTC](4)-14benzene- 19H(2)O (4), respectively. Furthermore, crystal 1 reacted with 12 via single-crystal -to-single-crystal transformation to produce [Ni2(C26H52N10)](3)[C9H3O6](4)(l(3))(4).nl(2).17H(2)O (5) that consists of positively charged framework incorporating nickel(III) and nickel(II) ions and the channels including 13 and 12.