Hydrothermal assembly and crystal structures of three novel open frameworks based on molybdenum(VI) oxides

The hydrothermal syntheses, crystal structures and thermal behaviours of th ree new 3-D framework molybdenum(VI) oxide hybrid materials, [MoO3(pyz)(0.5 )] 1 (pyz = pyrazine), [{Cu(pip)(0.5))MoO4] (pip = piperazine) 2 and [H2Mo2 Cu3O10] 3, are presented. 1 and 2 that are hybrids of inorganic oxide layer s and bridging organodiamine ligands exhibit a covalent/coordinalion framew ork connectivity: 3 represents a novel open framework example of bimetallic oxides based on Mo-VI and Cu-II. These new materials are synthesized by a judicious selection of organodiamines accompanied by the concurrent alterat ion of initial reaction conditions. The choice of organodiamines is found t o be critical to the framework composition and construction of solid archit ectures. The chiral framework of 1 and the 3-D structure of 2 are character ised by one-dimensional channels along the orthorhombic and triclinic b axi s respectively circumscribed by six {MoO5N} octahedra and two pyz molecules in 1, and by two {MoO4} tetrahedra, four {CuO4N} square pyramids and two p ip molecules in 2. The 3-D open framework of 3 has six-ring channels along the triclinic b axis. The thermal behaviours of the three solids are simila r, undergoing a phase transition in the range 260-420 degrees C upon the re moval of organic ligands in 1 and 2 and dehydration in 3.