Dependence of photoinduced energy transfer on orientation of acceptor lanthanide ions with respect to π-plane of naphthalene in naphthalene-linked six-member crown ethers

Author： Sardar Pinki Saha Samanta Subhodip Roy Maitrayee Basu Ghosh Sanjib

Publisher： Taylor & Francis Ltd

ISSN： 1362-3028

Source： Molecular Physics, Vol.106, Iss.6, 2008-03, pp. : 827-840

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Abstract

The photoinduced energy transfer (ET) from naphthalene (N) to rare earth ions Eu3+/Tb3+ has been studied in the lanthanide ion complexes of 1,4-naptho-22-crown-6 (system-I) using [image omitted]as counter ion. The ET efficiency and rate constants have been calculated and the values compared with the metal ion complexes of three other naptho-crown-6 systems (II to IV), which have different orientation of the naphthalene unit with respect to the crown ring. Geometry optimization by DFT method indicates a subtle difference in the geometries of systems I and II that is reflected in substantial differences in the ET efficiencies of the two systems. In all the systems ET occurs by an exchange mechanism involving the lowest triplet state of the naphthalene moiety. The ratios of the overlap integral of the Eu3+/Tb3+ complexes in different crown ethers involved in such an exchange mechanism have been estimated.