Protonated N-heterocycle-templated supramolecular frameworks built of triangular molybdenum(IV) clusters

A series of porous supramolecular complexes (Hoxine)2 · [Mo3O4(C2O4)3(H2O)3] · 5H2O (1),(Hphen)2 · [Mo3O4(C2O4)3(H2)3]  · 0.5C2H5OH · 7H2O (2), H2bpy · [Mo3O4(C2O4)3(H2O)3] · 2.5H2O (3), H2TTD · [Mo3O4(C2O4)3(H2O)3] · C2H5OH · 3H2O (4), (oxine = 8-hydroxyquinoline, phen = 1,10-phenanthroline, bpy = 4,4′-bipyridine, TTD = triethylene diamine) have been prepared and characterized by single-crystal X-ray crystallography, elemental analysis and infrared spectroscopy. Self-assembly of [Mo3O4(C2O4)3(H2O)3]2− directed by H-bonding association between the coordination water molecules and oxalate groups forms 2-D host H-bonded single layer in 1, double layer in 2 and 3, and undulated layer in 4 depending on the nature of the guest protonated N-heterocycles. Unlike cis-Hoxine+ or Hphen+ that employs lattice water molecules H-bonded to them to interconnect the host layers, trans-H2bpy2+ or H2TTD2+ acts a linker between the neighboring host layers to form 3-D supramolecular frameworks with channeled structures wherein the guest protonated cations are located.

Counter-cation-directed self-assembly of [Mo3O4(C2O4)3(H2O)3]2− through H-bonds forms host H-bonded single layer in 1, double layer in 2 and 3, and undulated layer in 4. Unlike cis-Hoxine+ or Hphen+, trans-H2bpy2+ or H2TTD2+links the neighboring host layers into 3-D open frameworks.Figure optionsDownload as PowerPoint slide