A metal-organic bilayer open framework with a dynamic component: Single-crystal-to-single-crystal transformations

A metal-organic bilayered open framework, [Ni2(C26H52N10)]3[BTC]4·6C5H5N·36H2O (BOF-1, 1), has been prepared by the self-assembly of a new bismacrocyclic nickel(II) complex [Ni2(C26H52N10)(Cl)4]·H2O (A) and sodium 1,3,5-benzenetricarboxylate (Na3BTC) in the mixture of water/DMSO/pyridine. The X-ray crystal structure of 1 shows that 2D layers with the cavities of brick-wall motifs (22.6 × 14.3 Å2) are formed by the coordination of the nickel(II) complex with BTC3- ions and that the two 2D layers are linked with the p-xylyl bridging groups of the bismacrocycles as pillars to generate 3D channels in the bilayered framework. The voids of the channels occupy 61% of the total volume, which are filled with pyridine and water guest molecules. When 1 was dried at 75 °C for 1.5 h, [Ni2(C26H52N10)]3[BTC]4·4H2O (2) resulted by maintaining the single-crystallinity, which exhibited a dramatic decrease in the interlayer spacing as well as changes in the cell parameters. Solid 2 differentiates various alcohols such as MeOH, EtOH, isopropyl alcohol, and benzyl alcohol in toluene. When 1 was immersed in insoluble solvents such as pyridine and benzene, some guest molecules were exchanged with the aromatic molecules to give [Ni2(C26H52N10)]3[BTC]4·20pyridine·6H2O (3) and [Ni2(C26H52N10)]3[BTC]4·14benzene·19H2O (4), respectively. The guest-exchange processes also involve single-crystal-to-single-crystal transformation. Copyright © 2002 American Chemical Society.