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The decay of Yb 169 by electron capture has been studied with permanent magnet spectrographs and scintillation counter techniques. Multipolarities of all transitions (including mixing) have been deduced. A level scheme is proposed. Two metastable levels of 4X10~7 and 4.5X10" 8 second have been found, in addition to the well-known 6.4 X 10~7 sec level. These metastable levels are all depopulated by D+Q mixtures in which the dipole radiation is greatly retarded (by factors of 10 6 to 10 8 ) and the quadrupole radiation is retarded by factors of 10 2 to 10 3 as compared to the single-particle estimates. For certain transitions the corrections to the Ml internal conversion coefficients (necessary because of finite nuclear size) have been obtained for the K, L\ and Lu shells. The screening correction for the K-LL Auger lines has been obtained for this nucleus (Z=69).

The synthesis of a trichlorodimethoxybenzene substituted Zn(II) metalloporphyrin-pyridine conjugate 12 is reported. The structures of the porphyrins were established by MS, 1 H NMR and elemental analysis. Protonation of the pyridine moiety leads to a strong reduction of fluorescence intensity of 12.Porphyrins are remarkable coordinating ligands since they form metallocomplexes with almost all of the metals of the periodic table. 1 The considerable progress achieved in porphyrin chemistry can be attributed to the extensive studies carried out on the syntheses of variously substituted porphyrin derivatives. 2 We are interested in designing a series of donor-bridge-acceptor systems to give information on how the nature of the spacer between the donor and the acceptor influences the electron transfer process. 3 In this paper, we report the synthesis of a porphyrin donor-bridge-acceptor system. The donor and the acceptor are zinc porphyrin and trichlorodimethoxybenzene, 4 respectively.In Scheme 1, the synthetic route to the functionalized trichlorodimethoxybenzene 4 is shown. The starting compound 1 was prepared in five steps from 2,5-dihydroxytoluene according to the reported methods. 5 Perkin reaction of 1 and acetic anhydride with potassium acetate gave the cinnamic acid 2 in 81% yield. Reduction of 2 in the presence of palladium-on-charcoal afforded the propionic acid 3 in 85% yield. Chlorination of 3 with SOCl 2 followed by treatment with 2,6-diaminopyridine and 1,3-phenylenediamine in Et 2 O gave 4a and 4b in 72% and 86% yields, respectively.In Scheme 2, the syntheses of 8 and 11 are shown. Previously published procedures were used for the syntheses of 3,3¢-dimethyl-4,4¢-diethyldipyrromethane (5) 3b and ethyl 4¢-formyl-4-biphenylcarboxylate (6). 6 The porphyrin 8 was prepared in 22% yield from the cross-condensation of 5, 6, and benzaldehyde (7). The porphyrin 8, however, showed low solubility in the organic solvent, which made the purification by silica gel column chromatography difficult and caused a low yield. Therefore, meso-(3,5-ditert-butylphenyl)-2,2¢-dipyrromethane (9) 7 and 3,5-ditert-butylbenzaldehyde (10) were employed to provide enhanced solubility to the porphyrin. The porphyrin 11 was synthesized from 6, 9, and 10 in a 28% yield in the similar manner. The syntheses of 12 and 13 are shown in Scheme 3. Hydrolysis of 8 with NaOH in H 2 O/dioxane followed by treatment with SOCl 2 and 4a in CH 2 Cl 2 afforded the target compound 12 in 53% yield. Compound 12 was verified by spectroscopic analyses including 1 H NMR and MALDI-TOF mass spectra. The porphyrin 13 was prepared from 4b and 8 in 76% yield.The absorption spectra of the zinc complex 12 exhibited Soret band (S 2 ) at 407 nm and Q bands (S 1 ) at 535 nm and 571 nm in CH 2 Cl 2 , while the absorption spectra of the zinc complex 13 showed Soret band at 423 nm and Q bands at 550 nm and 588 nm in CH 2 Cl 2 , respectively. The fluorescence emission bands of 12 exhibited at 576 nm and 627 nm in CH 2 Cl 2 , and those of 13 showed at 600 nm and 648 nm in ...