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Titolo:
Lanthanide triple-stranded helical complexes with a substituted 2,6-pyridinedicarboxylate
Autore:
Platas-Iglesias, C; Piguet, C; Andre, N; Bunzli, JCG;
Indirizzi:
Univ Lausanne, BCH, Inst Inorgan & Analyt Chem, CH-1015 Lausanne, Switzerland Univ Lausanne Lausanne Switzerland CH-1015 CH-1015 Lausanne, Switzerland Univ Coruna, Dept Quim Fundamental, Acoruna 15071, Spain Univ Coruna Acoruna Spain 15071 t Quim Fundamental, Acoruna 15071, Spain Univ Geneva, Dept Inorgan Analyt & Appl Chem, CH-1211 Geneva, Switzerland Univ Geneva Geneva Switzerland CH-1211 Chem, CH-1211 Geneva, Switzerland
Titolo Testata:
JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS
fascicolo: 20, , anno: 2001,
pagine: 3084 - 3091
SICI:
1472-7773(2001):20<3084:LTHCWA>2.0.ZU;2-E
Fonte:
ISI
Lingua:
ENG
Soggetto:
MAGNETIC-RESONANCE SHIFTS; PHOTOPHYSICAL PROPERTIES; PREDETERMINED PROPERTIES; TEMPERATURE-DEPENDENCE; BUILDING-BLOCKS; LUMINESCENCE; TRANSITION; METAL; FIELD; EQUILIBRIUM;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
57
Recensione:
Indirizzi per estratti:
Indirizzo: Bunzli, JCG Univ Lausanne, BCH, Inst Inorgan & Analyt Chem, CH-1015 Lausanne, Switzerland Univ Lausanne Lausanne Switzerland CH-1015 anne, Switzerland
Citazione:
C. Platas-Iglesias et al., "Lanthanide triple-stranded helical complexes with a substituted 2,6-pyridinedicarboxylate", J CHEM S DA, (20), 2001, pp. 3084-3091

Abstract

A 4-aminophenylethynyl substituent has been grafted into the 4-position ofthe pyridine ring in dipicolinic acid to yield ligand L-4 the pK(a)'s of which are 8.77(5), 3.54(3), 2.58(1) and 1.01(3). Ligand L-4 reacts with trivalent lanthanide ions to give stable triple-stranded helical complexes in water (log beta (13) = 13.7(1) for Eu). The separation of the contact and pseudocontact contributions to the NMR paramagnetic shifts according to the crystal field independent method points to a single axial structure for [Ln(L-4 - 2H)(3)](3-) along the series Nd-Yb. The solution structure generated by using the dipolar shifts compares well with that reported for the Eu-IIItris( dipicolinate), with a co-ordination polyhedron which can be described as a distorted tricapped trigonal prism. This is confirmed by a photophysical study of the Eu-III complex both in solution and in the solid state. The triplet state of co-ordinated L-4 lies at low energy (around 18 000 cm(-1) in water) resulting in a relatively poor sensitisation of Eu-III (quantum yield ca. 0.1% in methanol, lower in water) but in a sizable energy transfer to Yb-III.

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Documento generato il 04/04/20 alle ore 09:14:02