Synthesis, crystal structure and visible light emission of a new inorganic-organic hybrid pentaborate, [C6H14N][B5O6(OH)4]

A new organic-inorganic hybrid pentaborate [C6H14N][B5O6(OH)4] (1) has been synthesised hydrothermally in aqueous solution and characterised by single-crystal X-ray diffraction, FT-IR, DTA-TG and photoluminescence spectroscopy. It crystallizes in the monoclinic system, space group P21/c, with the lattice constants of a = 9.463 (2) Å, b = 14.005 (3) Å, c = 10.642 (2) Å, and β = 93.82(3)°. The structure consists of isolated [B5O6(OH)4]− groups interlinked by protonated cyclohexylamine via hydrogen bonding. Blue photoluminescence of 1 is observed upon UV excitation, which can be further enhanced and modified to near-white emission by thermal treatment. The maximum emissions and peak shapes of 1-250 °C are also tunable with various excitation wavelengths in the region of 350-470 nm. This compound provides a novel example of organically templated borate materials potential for display and lighting applications.