Abstract
The novel tin bromido aluminates [Sn(3) (AlBr(4) )(6) ](Al(2) Br(6) ) (1), Sn(AlBr(4) )(2) (2), [EMIm][Sn(AlBr(4) )(3) ] (3) and [BMPyr][Sn(AlBr(4) )(3) ] (4) ([EMIm]: 1-ethyl-3-methylimidazolium, [BMPyr]: 1-butyl-1-methyl-pyrrolidinium), are obtained from a ionic-liquid-based reaction of AlBr(3) and SnCl(2) or SnBr(2) , resulting in colorless and transparent crystals. 1 contains a neutral, inorganic (∞) (3) [Sn(3) (AlBr(4) )(6) ] network filled with intercalated Al(2) Br(6) molecules. 2 represents a 3D structure isotypic to Pb(AlCl(4) )(2) or α-Sr[GaCl(4) ](2) . 3 and 4 exhibit infinite (∞) (1) [Sn(AlBr(4) )(3) ](n-) chains that are separated by the voluminous [EMIm](+) /[BMPyr](+) cations. All title compounds contain Sn(2+) coordinated by AlBr(4) tetrahedra, resulting in chains or 3D networks. Moreover, all title compounds show photoluminescence due to Br(-) →Al(3+) ligand-to-metal charge-transfer excitation, followed by 5s(2) p(0) ←5s(1) p(1) emission on Sn(2+) . Most surprisingly, the luminescence is highly efficient (quantum yield >50 %). Specifically, 3 and 4 exhibit outstanding quantum yields of 98 and 99 %, which are the highest values observed for Sn(2+) -based luminescence so far. The title compounds have been characterized by single-crystal structure analysis, elemental analysis, energy-dispersive X-ray analysis, thermogravimetry, infrared and Raman spectroscopy, UV-Vis and photoluminescence spectroscopy.