Templated pentaborates have potential application as LEDs. The organically templated pentaborate [C2H8N][B5O6(OH)4] (A) was synthesized by the reaction of dimethylamine with boric acid in pyridine solution and the compound was characterized by elemental analysis, FT-IR and photoluminescence spectroscopy as well as TG-DTA analysis and powder X-ray diffraction. The crystallographic structure of A was determined by single-crystal X-ray diffraction. It crystallizes in the monoclinic system, space group P with the parameters of a = 8.893(7) (Å), b = 8.902(7) (Å), c = 16.967(16) (Å), α = 102.620(12)°,β = 102.817(11)°, γ = 99.107(5)°, V = 1247.5(18) Å3 and Z = 4. The luminescent properties of the compound were studied, and a purple-pink luminescence occurs with an emission maximum at 473 nm. The photoluminescence of A can be changed from purple-pink to white by means of a simple heat-treatment process. The white-light-emission of the as-synthesized sample G makes the pentaborate a good candidate for display and lighting applications in white LEDs.