Host-Guest and Photophysical Behavior of Ti8 L12 Cube with Encapsulated [Ti(H2 O)6 ] Species.

Titanium-based coordination cages could be interesting for both supramolecular and photophysical chemistry. This work reports an unprecedented host-guest system, [Ti(H2 O)6 ]@Ti8 L12 , which is comprised of the first Ti-based coordination cube and the unusual titanium aquo species. Due to the abundant intra-cube O-H⋅⋅⋅O hydrogen bonds, the [Ti(H2 O)6 ]@Ti8 L12 complex is rather stable both in solid and solution states, confirmed by X-ray diffraction and ESI-MS analysis. The encapsulated [Ti(H2 O)6 ] species shows influence on the light absorption, photoluminescent, and photocurrent properties. Moreover, ultrafast transient absorption spectroscopy has been applied to study the photodynamics of both free and [Ti(H2 O)6 ] guest encapsulated Ti8 L12 cube, confirming that the host-guest system produces a slightly longer-lived excited state. Therefore, this work presents the first [Ti8 L12 ] cube with unusual [Ti(H2 O)6 ] guest and also provides an interesting supramolecular model for the host-guest photophysical study.