A series of novel gallium and indium borates constructed from [B5O8(OH)2]3− clusters and metal complex linkers

Four novel gallium and indium borates, [M(en)2][B5O8(OH)2]·H2O (M=Ga (1), In (2); en=ethylenediamine), [In(dap)2][B5O8(OH)2]·H2O (3, dap=1,2-diaminopropane), [In(dien)][B5O8(OH)2] (4, dien=diethylenetriamine), have been hydrothermally synthesized and characterized by IR spectra, elemental analyses, powder X-ray diffraction, single crystal X-ray diffraction, and thermogravimetric analyses. Compounds 1, 2 and 3 are isostructural and consist of one-dimensional (1-D) chains built up from [B5O8(OH)2]3− clusters and Ga-/In-complex linkers. The structure of compound 4 features a 1-D chain containing 8-member rings built by [B5O8(OH)2]3− clusters and {In2O4} dimeric cluster linkers which have never observed in the structural chemistry of borates to date. The H-bonding interactions between adjacent chains lead to 3-D supramolecular network structure. - Graphical abstract: Four novel gallium and indium borates with one-dimensional structures built by B5O8(OH)23+ clusters and metal complex linkers have been successfully synthesized under hydrothermal conditions. Highlights: ► Four new Ga/In borates have been hydrothermally made. ► The helical/ribbon-like chains made of B5O8(OH)23+ clusters and Ga-/In-complex linkers. ► The chains form novel 3-D supermolecule framework via H-bonds.