Solvent-controlled synthesis of an Al-12-oxo molecular ring and Al-24-oxo truncated metallo-cube

Highly symmetrical molecules with beautiful geometries are ubiquitous in nature. It has inspired creative ideas of the perfect combination of geometry and molecular structural chemistry. Some metal clusters with regular geometric polyhedra have been reported, but such highly symmetric polyhedra for Al-oxo clusters are really scarce on account of the fast hydrolysis of Al3+ ions. Herein, a [Al-12(CH3O)(24)(NAP)(12)]center dot 4DMF center dot 2H(2)O center dot 2CH(3)OH (Al-12, NAP(-) = 2-naphthoic acid) nanoring was synthesized by the solvothermal reaction of AlCl3 center dot 6H(2)O, 2-naphthoformic acid (HNAP) and triethylamine (Et3N) in CH3OH and DMF. Interestingly, the regulation from ring-shaped Al-12 to [Al-24(OH)(32)(CH3O)(22)(CH3OH)(2)(NAP)(12)]center dot 6Cl center dot 2H(2)O center dot 2CH(3)OH (Al-24) metallocage is realized by only changing the reactive solvents. The Al-24 metallocage can be seen as one of 13 Archimedean polyhedra, a truncated cube composed of eight Al-3 triangles and six Al-8 octagons by sharing vertical Al3+ ions. In addition, high-resolution electrospray ionization mass spectrometry (HR-ESI-MS) reveals that the metallic skeletons of Al-12 and Al-24 can be maintained stable in CH3OH and CH2Cl2. Furthermore, Al-12 and Al-24 emit blue luminescence and exhibit photocurrent responses under LED light illumination.