Solvatochromism of lanthanide complexes containing the hemicyanine chormophore

The solvatochromic properties of a hemicyanine bromide with a long alkyl ch ain and of the corresponding hemicyanine compounds with lanthanide containi ng anions are described. The anions are the tetrakis(pyrazolonato)lanthanid e(III) and the tetrakis(beta-diketonato) lanthanide(III) complexes. The syn theses of the compounds are described. Absorption spectra in 16 different o rganic solvents were recorded. Strong solvent effects are observed for the hemicyanine bromide and for the lanthanide compounds. A color change of the solutions from yellow to orange red is observed, depending on the solvent used. The solvatochromism is explained taking dipolar interactions between the solvent and the complexes into account. (C) 1999 Elsevier Science B.V. All rights reserved.