New types of 3D organically templated Zn2+/Cd2+-Cu+ mixed metal sulfites.

ABSTRACT

Two types of new organically templated mixed-metal sulfites, namely, [H(2)pip][NaZn(2)Cu(SO(3))(4)] (1) and [H(2)pip][CdCu(4)(SO(3))(4)] (2) (pip = piperazine), have been synthesized under hydrothermal conditions and structurally characterized. Both compounds exhibit a novel 3D mixed-metal inorganic framework with organic template molecules occupying the tunnels of the inorganic skeleton. Compound 1 features a 2D Zn(2)Cu(SO(3))(4)(3-) layer parallel to the ac plane in which the 1D chains of Zn(SO(3))(2)(2-) anions along the c axis are interconnected with the Cu(+) ions via Cu-S bonds. Neighboring Zn(2)Cu(SO(3))(4)(3-) layers are further interconnected by bridging Na(+) ions via Na-O-S bonds into a 3D network, forming 1D tunnels along the a axis which are occupied by the doubly protonated piperazine cations. Compounds 2 features a novel 3D inorganic framework of CdCu(4)(SO(3))(4)(2-) with 2D layers based on Cu(4)(SO(3))(4)(4-) cubanelike clusters. The cluster layers are further interconnected by Cd(II) ions, forming 1D tunnels of eight-membered rings along the c axis in which the piperazine template cations are located. Luminescent property measurements as well as band structure calculations based on density functional theory methods were also made.