A Novel Right-Angled Ligand that Forms Polymeric Metal−Organic Frameworks with Nanometer-Sized Square Cavities

A new right angle-shaped ligand, 2,2‘-bis(4-pyridyl)-9,9‘-spirobifluorene ( L ), is designed and synthesized. Treatment of L with silver(I) ions leads to linear polymeric metal−organic frameworks, [Ag( L ) 2 ] + ( 1 ), that feature square subunits. Single-crystal X-ray analysis reveals that [Ag( L ) 2 ] + has a one-dimensional double-stranded polymeric chain comprising square grids with cavity dimensions of ca. 8 Å × 8 Å. By π−π stacking of adjacent double-stranded chains, the structure is extended into a two-dimensional (2D) layer framework with a unique quasi-aperture (dimensions of ca. 14 Å × 8 Å). Each 2D layer is inclined and mutually interpenetrated, which gives rise to the three-dimensional interlocked network structure. Compound 1 ·(BF 4 )(CH 3 OH) crystallizes in the monoclinic system, space group C 2/ c, with chemical formula C 71 H 49 N 4 OBF 4 Ag, a = 25.709(1) Å, b = 14.4164(6) Å, c = 15.6865(7) Å, β = 109.220(2)°, and Z = 4.