Utilize este identificador para referenciar este registo: http://hdl.handle.net/10451/20901
Título: Synthesis, conformational behaviour, alkali and alkaline-earth metal cation extraction and transport studies of p-tert-butyldihomooxacalix[4]crowns
Autor: Marcos, PM
Felix, S
Ascenso, JR
Santos, MA
Segurado, MAP
Pereira, JLC
Palavras-chave: Chemistry, Organic
Data: 2002
Editora: PERGAMON-ELSEVIER SCIENCE LTD
Citação: TETRAHEDRON. - Vol. 58, n. 45 (2002), p. 9223-9230
Resumo: 1,3-Dimethoxy-p-tert-butyldihomooxacalix[4]arene-crown-6 (4) was synthesized for the first time. 4 was isolated in a partial cone A conformation in solution at room temperature, as established by NMR measurements (H-1, C-13, COSY and NOESY). Conformational behaviour of 4 and p-tert-butyldihomooxacalix[4]-crown-5 (2) and crown-6 (3) was studied by dynamic H-1 NMR and by MD/MM calculations. Two-phase (water/CH2Cl2) picrate extraction studies and transport experiments with the same salts through a CH2Cl2 membrane were performed to evaluate the binding properties of these ligands towards alkali and alkaline earth metal cations. 2 and 3 are poor phase transfer agents for all cations, while 4 is a reasonable extractant for the alkali cations, showing preference for Cs+. However, all three calixcrowns are good carriers for the alkali cations and display a very selective transport for Ba2+. (C) 2002 Elsevier Science Ltd. All rights reserved.
URI: http://hdl.handle.net/10451/20901
ISSN: 0040-4020
Aparece nas colecções:FF - Produção Científica 2000-2009

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