Guest-driven luminescence: lanthanide-based host-guest systems with bimodal emissive properties based on a...

A series of discrete closed, semi-closed, and polymeric lanthanide-based [{Ln(H(2)O)(8)}(3+)subsetLn(III)(2)L(4)] host-guest systems with tetragonal prism-like structure have been designed and synthesized through the ligand-dominated approach. These nanoscopic cages are robust and can be maintained upon guest exchange. Within the restricting space, the luminescence intensity of the encapsulated [Ln(H(2)O)(8)](3+) species is dramatically enhanced due to the vibrational movements originating from the O-H oscillators in the coordinated water molecules being effectively reduced by the host-guest H-bonding interactions. Based on the guest-driven approach, tunable emission and bimodal emission (UV/Vis/NIR) of these [{Ln(H(2)O)(8)}(3+)subsetLn(III)(2)L(4)] supramolecular systems are successfully realized. Moreover, the strong luminescence originating from [{Ln(H(2)O)(8)}(3+)subsetLn(III)(2)L(4)] host-guest system can be quenched by encapsulation of d-block metal quenchers, such as Fe(3+) and Cu(2+), through solid-state f-d metal exchange. Additionally, this study demonstrates that the photoinduced solid-state guest-independent emission spectrum could be one of the most diagnostic techniques for monitoring the solid-state guest-exchange process.