Abstract— Excited state emission and absorption decay measurements have been made on the cage‐type cryptate complexes [M bpy.bpy.bpy] n+ , where M n+ = Na + , La 3+ , Eu 3+ , Gd 3+ or Tb 3 + and [bpy.bpy.bpy] is a tris‐bipyridine macrobicyclic cryptand. Excitation has been performed in the high intensity 1 π‐π* cryptand band with maximum at about 300 nm. Experiments have been carried out in H 2 O or D 2 O solutions and at 300 and 77 K to evaluate the rate constants of radiative and nonradiative decay processes. For M n+ = Na + , La 3+ and Gd 3+ the lowest excited state of the cryptate is a 3 ππ* level of the cryptand which decays in the microsecond time scale at room temperature in H 2 O solution and in the second‐millisecond time scale at 77 K in MeOH‐EtOH. For M n+ = Eu 3+ , the lowest excited state is the luminescent 5 D 0 Eu 3+ level which in H 2 O solution is populated with 10% efficiency and decays to the ground state with rate constants 2.9 × 10 3 s _1 at room temperature and 1.2 × 10 3 s − ′ at 77 K. The relatively low efficiency of 5 D 0 population upon 1 ππ* excitation is attributed to the presence of a ligand‐to‐metal charge transfer level through which 1 ππ* decays directly to the ground state. For M n+ = Tb 3+ the lowest excited state is the luminescent 5 D 4 Tb 3+ level. The process of 5 D 4 population upon 1 ππ* excitation is ˜100% efficient, but at room temperature it is followed by a high‐efficiency, activated back energy transfer from the 5 D 4 Tb 3+ level to the 3 ππ* ligand level because of the relatively small energy gap between the two levels (1200 cm _1 ) and the intrinsically long lifetime of 5 D 4 . At 77 K back energy transfer cannot take place and the 5 D 4 Tb 3* level deactivates to the ground state with rate constant 5.9 × 10 2 s ‐ ′ (H 2 O solution). The relevance of these results toward the optimization of Eu 3+ and Tb 3+ cryptates as luminescent probes is discussed.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotoinduced electron-transfer reactions of poly(pyridine)ruthenium(II) complexes with europium(III/II) cryptatesN. Sabbatini, S. Dellonte, A. Bonazzi, M. Ciano, and V. BalzaniCite this: Inorg. Chem. 1986, 25, 11, 1738–1742Publication Date (Print):May 1, 1986Publication History Published online1 May 2002Published inissue 1 May 1986https://pubs.acs.org/doi/10.1021/ic00231a003https://doi.org/10.1021/ic00231a003research-articleACS PublicationsRequest reuse permissionsArticle Views187Altmetric-Citations13LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts
Lumineszenzmarker für biologische Anwendungen müssen in wäßrigen Systemen eine hohe Lumineszenzlebensdauer und ‐quantenausbeute aufweisen. Der Ligand 1 bildet mit Eu 3⊕ Komplexe, die den Anforderungen gerecht werden. Das Lanthanoid‐Ion wird vom Makrocyclus eingeschlossen und von den beiden zusätzlichen bpy‐„Schwenkarmen”︁ regelrecht verkapselt. Die Effizienz des Energietransfers vom Liganden zum Metall‐Ion ist dadurch optimal, und Wassermoleküle können den angeregten Zustand von letzterem nicht desaktivieren. magnified image
Luminescence markers for biological application must have long luminescence lifetimes and high quantum yields in aqueous systems. Ligand 1 forms complexes with Eu3⊕, which fulfill these criteria. The lanthanide ion is encapsulated by the macrocycle and the two additional mobile arms. The efficiency of the energy transfer from ligand to metal ion is thereby optimized, and water molecules cannot deactivate the excited state of the metal ion.
Complexes in which the Eu3+, Tb3+, and Gd3+ ions are encapsulated in the p-t-butylcalix[4]arene-tetra-acetamide ligand, (1) have been synthesized and their photophysical properties investigated; the Tb3+ complex exhibits a high luminescence quantum yield (0.2) and a long luminescence lifetime (1.5 ms) upon ligand excitation in aqueous solution.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInfluence of fluoride ions on the absorption and luminescence properties of the [Eu.cntnd.2.2.1]3+ and [Tb.cntnd.2.2.1]3+ cryptatesN. Sabbatini, S. Perathoner, G. Lattanzi, S. Dellonte, and V. BalzaniCite this: J. Phys. Chem. 1987, 91, 24, 6136–6139Publication Date (Print):November 1, 1987Publication History Published online1 May 2002Published inissue 1 November 1987https://pubs.acs.org/doi/10.1021/j100308a016https://doi.org/10.1021/j100308a016research-articleACS PublicationsRequest reuse permissionsArticle Views189Altmetric-Citations44LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access options Get e-Alerts
