Synthesis and structural characterization of three 3-D aluminogermanates with different topologies

Abstract

Three 3-D aluminogermanates L-[C₂NH₈][AlGe₃O₈] (1), D-[C₂NH₈][AlGe₃O₈] (2) and [Ni(en)₃][Al₃Ge₃O₁₂(H₂en)_0.5] (3) (en = 1,2-ethanediamine) have been successfully synthesized through a hydrothermal synthesis method (1 and 2 were obtained as a mixture in one autoclave). Crystal structural analysis reveals that three compounds, 1, 2 and 3, are made up of GeO₄ (AlO₄) tetrahedra. Compounds 1 and 2 with a typical GIS topology are composed of 4-rings, while 3 is constructed exclusively from 3-rings with a JST topology. Compounds 1 and 2 are enantiomers and crystallize in chiral space groups P4₃2₁2 and P4₁2₁2, respectively. In compound 3, rigid chiral transition-metal complex cations, [Ni(en)₃]²⁺, and protonated ethylenediamine cations work together as structure directing agents (SDAs) and induce two different kinds of cages ([3⁸·10⁶] and [3⁴·6·10³]), which further construct the final structure.