Synthesis and characterization of a new chiral open-framework indium phosphite with intertwined host and guest helices

A new chiral open-framework indium phosphite In3(HPO3)6(H3DETA)·2H2O 1 has been synthesized under hydrothermal conditions using achiral diethylenetriamine (DETA) as template and characterized by single crystal X-ray diffraction, powder X-ray diffraction, IR spectroscopy, TGA, ICP–AES and elemental analyses. Single crystal X-ray diffraction analysis reveals that the 3D inorganic framework is built up by alternation of InO6 octahedra and HPO3 pseudo-pyramids. Interestingly, the right-handed inorganic helical ribbons are presented in the 3D open-framework while fascinating hydrogen-bonded helices are self-assembled under hydrothermal conditions between organic template molecules and H2O molecules. It is worth noting that the guest hydrogen-bonded helical chain and the host helical ribbon of inorganic framework show the same chirality and intertwine with each other along the b axis. Further understanding of the hydrogen bonds between guest molecules and inorganic framework demonstrates that the flexible DETA molecule may conduce to the formation of the chiral framework. Crystal data: In3(HPO3)6·(H3DETA)·2H2O, Monoclinic, P21 (No. 4), a = 9.2713(19) Å, b = 14.453(3) Å, c = 9.996(2) Å, β = 116.16(3)°, V = 1202.2(4) Å3, and Z = 2, Flack parameter: 0.0(4).

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► It is the first main group metal phosphite with chiral open-framework structure.
► It possesses special intertwined host helical ribbons and guest helical chains.
► The hydrogen bonds play an important role in the formation of the chiral framework.