Incorporation of Rare-Earth Complex Eu(TTA)₄C₅H₅NC₁₆H₃₃ into Surface-Modified Si−MCM-41 and Its Photophysical Properties

The incorporation of the rare-earth complex [C 5 H 5 NC 16 H 33 ][Eu(TTA) 4 ] into surface-modified mesoporous molecular sieve Si−MCM-41 via reactions of the surface Si−OH with different silylation agents such as (C 2 H 5 O) 3 Si(CH 2 ) 2 NH(CH 2 ) 2 NH 2 (NSED), (C 2 H 5 O) 3 Si(CH 2 ) 3 NH 2 (APTES), and (C 2 H 5 O) 3 Si(CH 2 ) 3 CN (TSBT) and their photophysical properties were studied. The results show that the surface silylation of Si−MCM-41 provides a unique chemical environment for the incorporated [C 5 H 5 NC 16 H 33 ][Eu(TTA) 4 ] complex. Hydrogen-bonding interactions of the rare-earth complex with its surrounding silylating agents alter the photophysical properties of the rare-earth complex. The emission intensity and color purity of the excited rare-earth complex in these surface-silylated Si−MCM-41 materials increase in the order of Si−MCM-41 < TBST−Si−MCM-41 < APTES−Si−MCM-41 < NSED−Si−MCM-41. Because of the strongest hydrogen bonding in NSED−Si−MCM-41, the rare-earth complex only emits light with a single wavelength, corresponding to 5 D 0 − 7 F 2 . This phenomenon is rarely seen in the luminescence of rare-earth complexes. The UV stability and lifetime of Eu 3+ in the rare-earth complex were also studied, and the results show that the incorporated rare-earth complex exhibits higher UV stability and increased lifetime compared to the pure rare-earth complex.