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Rare earth ion‐exchanged zeolites exhibit a tremendous enhancement of luminescence upon treatment with suitable organic complexing agents, as reported here. For Eu3+ exchanged zeolite X, the β‐diketone 1‐thienyl‐4,4,4‐trifluoro‐1,3‐butane‐1,3‐dione leads to the formation of intra‐zeolite complexes. Fully coordinated complexes within the supercages may be obtained by the additional coordination of 1,10‐phenanthroline (see Figure).

Optical and structural properties of rare earth complexes with 2-pyridine carboxylic acid (' Hpic ') are evaluated by luminescence spectroscopy, decay measurements, X-ray crystal structure determination, FTIR, DTA and metal content analysis. Corresponding Tb 3+ and Eu 3+ complexes of this ligand are extraordinarily efficient with respect to their luminescence. In the crystalline state the series is isostructural and composed of M[Ln(pic) 4 ]ÁnH 2 O (M ¼ Na, NH 4 ; Ln ¼ Eu, Gd, Tb, Ho) with pic-linked [Ln(pic) 4 ] À units forming a chainlike structure, which gives rise to a one-dimensional exchange communication between the rare earth ions; this energy transfer being confined to the chains. Energy transfer of the Coulomb type between the ligands appears to be of significance only, if suitable rare earth acceptor states are not accessible, as is shown for a series of [La(pic) 4 ] À series, in which La 3+ is gradually substituted by Tb 3+ or Eu 3+ .

The optical properties of Tb 3+ /Ce 3+ doped zeolites are elucidated with emphasis on ultraviolet (UV) and vacuum ultraviolet (VUV) excitation and luminescence. Ce 3+ sensitized Tb 3+ emission with quantum yields of 85 % may be obtained at 330 nm excitation. Low absorptivity at 254 nm due to low Ce 3+ concentrations or low Ce 3+ /Tb 3+ ratios, which are required for the suppression of UV components, restricts their applicability as phosphors for Hg-based discharges, e.g., in conventional fluorescent lamps. Near band edge excitation at 172 nm revealed an immediate quantum yield of 50 % enabled by a zeolite ® Ce 3+ (5d 1 ) ® Tb 3+ (4f 7 5d 1 ) energy transfer channel, which may be exploited for the down-conversion of the Xe 2 excimer emission.

The optical properties of Tb 3+ /Ce 3+ doped zeolites are elucidated with emphasis on ultraviolet (UV) and vacuum ultraviolet (VUV) excitation and luminescence. Ce 3+ sensitized Tb 3+ emission with quantum yields of 85 % may be obtained at 330 nm excitation. Low absorptivity at 254 nm due to low Ce 3+ concentrations or low Ce 3+ /Tb 3+ ratios, which are required for the suppression of UV components, restricts their applicability as phosphors for Hg-based discharges, e.g., in conventional fluorescent lamps. Near band edge excitation at 172 nm revealed an immediate quantum yield of 50 % enabled by a zeolite ® Ce 3+ (5d 1 ) ® Tb 3+ (4f 7 5d 1 ) energy transfer channel, which may be exploited for the down-conversion of the Xe 2 excimer emission.

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