Synthesis of Rigid <i>π</i>‐Conjugated Mono‐, Bis‐, Tris‐, and Tetrakis(terpyridine)s: Influence of the Degree and Pattern of Substitution on the Photophysical Properties

Abstract A series of rigid π‐conjugated mono‐, bis‐, tris‐, and tetrakis(terpyridine)s 3 – 8 was synthesized in high yields by means of Horner–Wadsworth–Emmons (HWE) reactions between benzyl phosphonates 1 and an aldehyde‐functionalized terpyridine derivative 2 . The photophysical properties of the materials in solution and in the solid state depend strongly both on the numbers of terpyridine moieties attached to the central phenyl cores and on the geometries of the compounds. The photophysical behavior of the ortho ‐substituted compounds 5 and 8 indicated significant changes in the geometries, together with major extensions of the effective π‐conjugated systems upon excitation. Bright green emission with high quantum yields was observed for the tetrakis(terpyridine) derivative 8 . (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2009)