A series of inorganic-organic hybrid cadmium borates with novel Cd-centred [Cd@B₁₄O₂₀(OH)₆]^2- clusters

Four novel inorganic-organic hybrid cadmium borates, namely [EAH]₂{(py)₂CdB₁₄O₂₀-(OH)₆]} (1, py = pyridine, EA = ethylamine), [PAH]₂{(py)₂CdB₁₄O₂₀(OH)₆]} (2, PA = propylamine), [pyH]₂{(py)₂CdB₁₄O₂₀(OH)₆]} (3) and {(AImH)₂CdB₁₄O₂₀(OH)₆]} (4, AIm = 1-(3-aminopropyl)imidazole) have been solvothermally synthesized and characterized by elemental analysis, thermogravimetric analysis, IR spectroscopy, UV-Vis-NIR spectroscopy, fluorescence spectroscopy, powder X-ray diffraction, and single-crystal X-ray diffraction, respectively. They represent the first hybrid cadmium borates that exhibit 3D supramolecular open-frameworks with different topologies. All the networks are formed by the unprecedented Cd-centred cluster [Cd@B₁₄O₂₀(OH)₆]^2-, and further link each other via a multipoint H-bond system. UV-Vis-NIR spectral investigation reveals that these borates are wide-band-gap semiconductors. Moreover, they display strong fluorescence emission around 430 nm, making them excellent candidates for optoelectronic applications as blue materials.