Ligand-field excited states of hexacyanochromate and hexacyanocobaltate as sensitisers for near-infrared luminescence from Nd(III) and Yb(III) in cyanide-bridged d-f assemblies (Journal article)

Lazarides, T./ Davies, G. M./ Adams, H./ Sabatini, C./ Barigelletti, F./ Barbieri, A./ Pope, S. J. A./ Faulkner, S./ Ward, M. D.

Crystallisation of [Co(CN)(6)](3-) or [Cr(CN)(6)](3-) with Ln(III) salts (Ln = Nd, Gd, Yb) from aqueous dmf afforded the cyanide-bridged d/f systems [Ln(dmf)(4)(H2O)(3)(mu-CN)Co(CN)(5)] (Co-Ln, discrete dinuclear species) and {[Cr(CN)(4)(mu-CN)(2)Ln(H2O)(2)(dmf)(4)]}(infinity) (Cr-Ln, infinite cyanide-bridged chains with alternating Cr and Ln centres). With Ln = Gd the characteristic long-lived phosphorescence from d-d excited states of the [M(CN)(6)](3-) units was apparent in the red region of the spectrum, with lifetimes of the order of 1 mu s, since the heavy atom effect of the Gd(III) promotes inter-system crossing at the [M(CN)(6)](3-) units to generate the phosphorescent spin-forbidden excited states. With Ln = Yb or Nd however, the d-block luminescence was completely quenched due to fast (> 10(8) s(-1)) energy-transfer to the Ln(III) centre, resulting in the characteristic sensitised emission from Yb(III) and Nd(III) in the near-IR region. For both Co-Nd and Co-Yb, calculations based on spectroscopic overlap between emission of the donor (Co) and absorption of the acceptor (Ln) suggest that the Dexter energy-transfer mechanism is responsible for the complete quenching that we observe.
Institution and School/Department of submitter: Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας
Keywords: transition-metal complexes,visible-light sensitization,lanthanide energy-transfer,one-dimensional chain,photophysical properties,er(iii) complexes,magnetic-properties,crystal-structures,extended arrays,d-block
ISSN: 1474-905X
Link: <Go to ISI>://000250589200011
Publisher: Royal Society of Chemistry
Appears in Collections:Άρθρα σε επιστημονικά περιοδικά ( Ανοικτά)

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