Premium
Synthesis, Characterization, and Electro‐Optical Properties of Zn II Complexes with π‐Conjugated Terpyridine Ligands
Author(s) -
Winter Andreas,
Friebe Christian,
Chiper Manuela,
Schubert Ulrich S.,
Presselt Martin,
Dietzek Benjamin,
Schmitt Michael,
Popp Jürgen
Publication year - 2009
Publication title -
chemphyschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.016
H-Index - 140
eISSN - 1439-7641
pISSN - 1439-4235
DOI - 10.1002/cphc.200800714
Subject(s) - terpyridine , moiety , delocalized electron , homo/lumo , conjugated system , cyan , density functional theory , intermolecular force , crystallography , chemistry , molecule , band gap , photochemistry , spectroscopy , raman spectroscopy , materials science , stereochemistry , computational chemistry , polymer , optoelectronics , organic chemistry , metal , art , physics , quantum mechanics , visual arts , optics
Leading light : A series of zinc(II) bis‐terpyridine complexes (see picture) is investigated by means of DFT calculations combined with Bader's quantum theory of atoms in molecules. Raman spectroscopy experiments and studies of the electro‐optical properties of the complexes in solution and the solid state are also performed to examine their potential as new emissive materials in light‐emitting devices.A series of nine zinc(II) complexes containing substituted 4′‐phenyl‐2,2′:6′,2′′‐terpyridines as ligands is synthesized and fully characterized. The ground‐state structures of four examples are calculated by means of DFT and their structural features are confirmed by experimental Raman spectroscopy. Special focus is placed on the degree of π‐electron delocalization between the terpyridine unit and the attached phenyl moiety. Applying Bader’s quantum theory of atoms in molecules (QTAIM) and visualizing the electron‐density distribution by intermolecular Δ ρ plots reveals an increase in ellipticity—and therefore π‐electron delocalization—for phenylvinyl‐substituted derivatives compared to phenylethynyl‐substituted ones. Experimentally, this is verified by spectroscopic means, because an increase in ellipticity goes along with a pronounced decrease of the HOMO–LUMO energy band gap. Overall, the lateral π‐conjugated substituents are found to strongly influence the electro‐optical properties of the complexes. In solution, the color of emission can be modulated from violet to cyan (425–487 nm) and high quantum yields ( Φ PL up to 0.60) are observed. Thin solid films of the complexes in a matrix of poly(methyl methacrylate) have been inkjet‐printed, and their photophysical behavior (bright emission, Φ PL up to 0.30) reveals their potential as new emissive materials for applications in light‐emitting devices.