Facile in situ syntheses of new templates and formations of three zinc phosphates

Three new organically templated zinc phosphates, namely, [dmdabco][Zn-2(HPO4)(3)]center dot(H2O) (1), [tmpip](0.5) [Zn-2(HPO4)(2)(H2PO4)] (2) and [tmpip][Zn-3(HPO4)(4)] (3) (dmdabco = N,N'-dimethyl-1,4-diazabicyclo [2,2,2]octane, tmpip = N,N,N',N'-tetramethyl-piperazinium), were successfully synthesized under solvothermal reactions and structurally characterized by single-crystal X-ray diffraction. The dmdabco(2+) and tmpip(2+) templating agents were derived respectively from simple in situ N-alkylation transformations between the methanol solvent and organic cyclic aliphatic diamines, 1,4-diazabicyclo[2,2,2]octane (dabco) in 1 and 1-methylpiperazine in 2 and 3. Such direct methylation feature is unique, and quite different from conventional Eschweiler-Clarke methylation in which an excess of formic acid and formaldehyde was required. Compound 1 exhibits a 4-connected 2D (4,4) net with pentameric [Zn2(HPO4)3] clusters as secondary building units (SBUs); 2 possesses a complex double layered structure with 12-ring windows. Compound 3 has a (3, 4)-connected 3D pcu architecture with heptameric [Zn-3(HPO4)(4)] clusters as SBUs, forming intersecting 8- and 12-ring channels. (C) 2014 Elsevier B.V. All rights reserved.