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It was shown that Tb3+ ion complexed with water-soluble calix[n]arenes becomes strongly fluorescent on the basis of energy-transfer luminescence (Φ = 0.02–0.20).

The two-photon Ionization spectra of perylene and naphthacene In hexane have been measured with tunable dye lasers. They have shown structure, which can be correlated with the onephoton absorption spectra. The signal-to-noise (S/N) ratio has been evaluated as functlons of the excitatlon wavelength and the laser pulse energy, and the detection limit depended on the excitation wavelength, the laser pulse energy, and the molar absorptivity. The lowest detection limits ( S I N = 3) of perylene and naphthacene were 50 pg/mL at 383 nm and 20 pg/mL at 407 nm, respectlvely; these dye laser resuits were superior to those obtained by nitrogen-laser excitation. Table I. Lasers Used in Two-Photon Ionization Experiments wavelength, nm dye solvent 337a 360-376 PBD ethanol/toluene, 50/50 ethanol/toluene, 50/50 p-dioxane 374-394 BBQ 396-412 DPS 412-424 POPOP p-dioxane 418-426 Bis-MSB p-dioxane 426-448 C-440 ethanol 444-472 (2-460 ethanol Nitrogen laser.Laser two-photon ionization in solution is a sensitive technique for detection of polynuclear aromatic hydrocarbons (1-8), drugs (3), quinones (5, 7), and vitamins (6). Experimental conditions such as laser power, bias voltage, irradiation position, and electrode configuration have to be optimized (9), and the design of a photoionization cell is very important for sensitive detection of the photoionization signal (1,2,4,5, 7, 8).The threshold for photoionization in solution is considerably lower than the ionization potential in the gas phase due to the polarization energy of the positive ion and the electron affinity of the solvent (1 0); differences are -1-3 eV for aromatic molecules (10-13). Thus, UV-vis lasers such as a nitrogen (1-3,5-8), excimer (4), or dye (3,8,12,13) laser should be able to ionize most aromatic molecules by two-photon processes. With the use of dye lasers, the two-photon ionization spectra (wavelength dependence of the photoionization signal at a constant photon flux of the laser pulse) were obtained for 9-methylanthracene (8), pyrene (121, fluoranthene (13), and N,N,N',"-tetramethyl-p-phenylenediamine (13,14). The results show that the spectrum has structure (8,12,13) and the signal tends to be larger for a shorter wavelength (8,(12)(13)(14). Since two-photon ionization is more efficient for molecules with larger molar absorptivities from the ground to the first excited states (5,7), wavelength dependence will be valuable in choosing an optimal wavelength for the twophoton ionization detection with the highest signal-to-noise

To induce the light-emitting properties of Tb3+ and Eu3+, calix[4]arenes bearing three amide groups (composing a metal-binding site) and one sensitizer group (phenacyl group or diphenacylcarbonyl group) on the lower rim have been synthesized. The high luminescence quantum yields (p = 0.27 for Tb3+ and 0.061 for Eu3+) were attained by both the metal-encapsulation effect of calix[4]arenes and the selection of a sensitizer with a proper energy gap. The possible energy-transfer mechanisms from the sensitizer group to the encapsulated metal ions are discussed. * We have found that in calix[4]arene-25,26,27,28-tetraoI the O-alkylation reaction in the presence of BaO or CaH, stops at the tri-0substituted stage 9-1 whereas the tri-0-substitution selectivity is not so reproducible in 5,l I , 17,23-tetra-terr-butylcalix[4]arene-25,26,27,28tetraol. The reason is not well understood. Here, we employed calix[4]~ arene-25,26,27,28-tetraol as the starting material but the reaction did not stop 'perfectly' at the tri-0-substituted stage as observed for the reaction with alkyl bromides or BrCH,C0,Et.9-1 '