Crystal Structure and Luminescence of Sn,I,Cs,Na-Y, a Lead-Free Zeolite Containing Tetrahedrally Distorted Cubes of Sn4I44+

Partially hydrated zeolite Cs, Na-Y (vertical bar Cs51Na24 vertical bar [Si117Al75O384]-FAU) was allowed to react with SnI2. The crystal structures of fully dehydrated Cs,Na-Y and of the partially hydrated product Sn, I, Cs, Na-Y (vertical bar(Na4Cs6Sn4I6)(0.625)Cs46Na21.5(H2O)(26)vertical bar [Si117Al75O384]-FAU) were determined by single-crystal crystallography using synchrotron X-radiation. They were refined in the space group Fd (3) over barm, (a = 24.838(2) angstrom and 24.873(2) angstrom) with all unique data to the final error indexes R-1 = 0.053 and 0.060 for the 1885 and 1400 reflections for which F-o >= 4 sigma(F-o), respectively. Tetrahedrally distorted Sn4I44+ cubes, symmetry (4) over bar 3m (T-d), center 7.9% of the supercages in the zeolite crystal studied. Each is supported there by four Na+ ions and six Cs+ ions that bridge between its I- ions and oxygen atoms of the zeolite framework. Each Sn2+ ion bonds to an additional I- ion in the plane of a 12-ring, which in turn bonds to a Sn2+ ion in a Sn4I44+ group in a neighboring supercage. In this way, the Sn4I44+ units connect to form a three-dimensional continuum with formula Na4Cs6Sn4I612+ per supercage. Partially hydrated zeolite Sn,I,Cs,Na-Y has a broad luminescence range from 400 to 800 nm. Upon further hydration, the luminescence spectrum evolved, and its color changed from pale yellow to white.