Growth of copper pyrazole complex templated phosphomolybdates: Supramolecular interactions dictate nucleation of a crystal

Five copper pyrazole complex based phosphomolybdates are self assembled at room temperature from an aqueous solution containing sodium molybdate, cupric chloride, and pyrazole acidified with phosphoric acid: one-dimensional (ID) chains in [{Cu(pz)(H2O)} {Cu(pz)(3)(H2O)} {Cu(pz)(4)} {P2Mo5O23}], 1, copper pyrazole complex intercalated two-dimensional (213) sheets in {Cu(pz)(2)(H2O)(4)} [{Cu(pz)(2)(H2O)}(2)] PCu(pz)(4)}(2) {HP2Mo5O23}(2)] center dot 6H(2)O, 2, hexadecameric water clusters incorporated between I D chains in [{Cu(pz)(4)}(3) {Cu(pz)(3)(H2O)}(2) {HP2Mo5O23}(2)] center dot 9H(2)O, 3, a water-mediated interpenetrated three-dimensional (3D) network in [{Cu(pz)(4)}(2) {H2P2Mo5O23}]center dot H2O, 4, and copper pyrazole complex pillared 2D phosphomolybdate sheets in [{Cu(pz)(2)}P2Mo2O12(H2O)(2)], 5. Detailed structural characterization of these solids was established by single crystal and powder X-ray diffraction techniques, FTIR, and thermal analysis. This paper proposes intuitive mechanisms to provide molecular insights into the role of in situ copper pyrazole complexes generated in solution in dictating a particular supramolecular assembly which eventually influences the nucleation of a crystal through a concerted condensation process. The role of the complexes as intercalant, pillaring unit, etc. has been demonstrated by these examples.