Jean-Claude Bunzli - Bent tridentate receptors in calamitic mesophases with predetermined photophysical properties: New luminescent lanthanide-containing materials

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  Publication Details (including relevant citation   information):

  Nozary,H., Piguet,C., Tissot,P., Bernardinelli,G., Bunzli,J.C.G.,   Deschenaux,R., Guillon,D. Journal of the American Chemical   Society 1998 120 (47) 12274-12288

  Abstract: A new synthetic strategy has been   developed to introduce bent and rigid tridentate   2,6-bis-(benzimidazol-2'-yl)pyridine cores into rodlike ligands   L11-17. The crystal structure of the nonmesogenic ligand L-13   (C39H37N5O4, triclinic, P (1) over bar, Z = 2) shows the expected   trans-trans conformation of the tridentate binding unit, which   provides a linear arrangement of the semirigid aromatic sidearms.   The crystal structure of the related mesogenic ligand L-16   (C61H81N5O4, triclinic, P (1) over bar, Z = 2) demonstrates the   fully extended conformation adopted by the lipophilic side   chains, leading to a slightly helically twisted I-shaped   molecule. A rich and varied mesomorphism results which can be   combined with the simultaneous tuning of electronic and   photophysical properties via a judicious choice of the spacers   between the rigid central core and the semirigid lipophilic   sidearms. Ligands L-13,L-14 react with Ln(NO3)(3). xH(2)O to give   quantitatively and selectively the neutral 1:1 complexes   [Ln(L-i)(NO3)(3)] (Ln = La to Lu), which are stable in the solid   state at room temperature but partially dissociate in   acetonitrile to give the cationic species [Ln(L-i)(NO3)(2)](+).   The crystal structure of [Lu(L-13)(NO3)(3)]. 3CH(3)CN (30,   LuC45H46N11O13, monoclinic, C2/c, Z = 8) reveals a U-shaped   arrangement of the ligand strand arising from the cis-cis   conformation of the coordinated tridentate binding unit.:This   drastic geometric change strongly affects the thermal behavior   and the photophysical and electronic properties of the lipophilic   complexes [Ln(L-14)(NO3)(3)]. Particular attention has been   focused on structure-properties relationships, which can be   modulated by the size of the lanthanide metal ions

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