Photofunctional materials are important because of their unique optical and electrical properties and are widely used in solar-energy conversion, semiconductor surface sensitization and modification, and nanoelectronics. [1][2][3][4][5] In recent decades, much effort has been directed toward the synthesis of pnictide-and chalcogenide-based inorganic semiconductor materials such as GaN, [6] SiC, [7] ZnO 2 , [8] and SnO 2 [9] because of their comparatively wide HOMO-LUMO gaps. There has been little investigation, however, of the photoelectronic properties of molecular solids.
Recently, by using an optically pure or a racemic mixture of a chiral cobalt complex such as [Co(en) 3 Cl 3 ] or [Co-(dien) 2 Cl 3 ] as the template, we prepared a series of openframework metal phosphates and oxides with chiral structure characters. [10,11] In order to explore new metal fluorides formed with a chiral cobalt complex as the template, we prepared a new cobalt complex-containing zirconium-silicon compound, namely [Co(en) 3 ] 2 (Zr 2 F 12 )(SiF 6 )•4 H 2 O (1), which contains an H-bonded network of discrete [Co(en) 3 ] 3+ , [Zr 2 F 12 ] 4À , and [SiF 6 ] 2À ions. Unexpectedly, this new compound exhibits intriguing photoelectronic effects in the near-UV region.
A single-crystal X-ray diffraction analysis [12] indicated that 1 crystallizes in a monoclinic unit cell with space group C2/c (no. 15). Each asymmetric unit (Figure 1) contains one unique Co atom, one unique Zr atom, and one unique Si atom that is located on the two-fold axis. Two [ZrF 7 ] 3À units share edges through difluoro bridges to form a [Zr 2 F 12 ] 4À pentagonalbipyramid cluster with ZrÀF bond lengths in the range of 1.988(4)-2.213(3) . The [Co(en) 3 ] 3+ cation and [SiF 6 ] 2À anion display a disordered and a near regular octahedral geometry, respectively, with the CoÀN and SiÀF distances in