Correlating structure and ion recognition properties of [Ni(salen)]-based polymer films

• Tipo: Artigo em Revista Científica Internacional
• Data: 2007

Autores

Tedim, J (Autor) Outra; Carneiro, A (Autor) Outra; Bessada, R (Autor) Outra; Patricio, S (Autor) Outra; Magalhaes, AL (Autor) FCUP; Freire, C (Autor) FCUP; Gurman, SJ (Autor) Outra; Hillman, AR (Autor) Outra

Revista

Título: Journal Of Electroanalytical Chemistry

Vol. 610

Páginas: 46-56

ISSN: 1572-6657

Editora: Elsevier

Indexação

ISI Web of Knowledge - 35 Citações

Scopus - 35 Citações

Classificação Científica

FOS: Ciências exactas e naturais > Química

Outras Informações

ID Authenticus: P-004-69T

DOI: 10.1016/j.jelechem.2007.06.025

Abstract (EN): The structural origins of ion recognition by electrochemically addressable poly[Ni(salen)] thin films are explored using in situ X-ray spectroscopy. XANES and EXAFS provided the local environment (nearest and next-nearest neighbours) around the Ni atom and solution-derived Ba2+ bound to the film. The Ni is covalently bound to two N and two O donors in square planar geometry, irrespective of film redox state and the presence (or absence) of bound Ba2+. The role of the Ni is purely structural; dramatic changes in i-E response accompanying Ba2+ uptake are assigned to the delocalised poly(salen) polymer spine. Ba2+ is trapped in a pseudo-crown formed by two methoxy O donors and two O donors shared with the Ni atom. The Ba2+ EXAFS signal from thick films (10 mu m) is significantly below that anticipated from electrochemical observations on thin films (<100 nm). Since EXAFS and XANES integrate populations over the entire film, this suggests that slow transport restricts Ba2+ access to the outer region of the film; surface sensitive XPS data confirm this. Combination of spectroscopic and electrochemical data suggest that, for exposure times of ca. 10(3) s, only sites in the outer ca. 1 mu m of the film are occupied; the implied diffusion coefficient of 10(-11) cm(2) s(-1) is consistent with a relatively compact solvated film.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 11