Premium
Interplay of α,α‐ versus α,β‐Conjugation in the Excited States and Charged Defects of Branched Oligothiophenes as Models for Dendrimeric Materials
Author(s) -
GonzálezCano Rafael C.,
Saini Geeta,
Jacob Josemon,
López Navarrete Juan T.,
Casado Juan,
Ruiz Delgado M. Carmen
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201302244
Subject(s) - delocalized electron , excited state , dication , absorption spectroscopy , conjugated system , branching (polymer chemistry) , absorption (acoustics) , ultrafast laser spectroscopy , photochemistry , triplet state , spectral line , chemistry , emission spectrum , materials science , ion , spectroscopy , atomic physics , physics , polymer , organic chemistry , quantum mechanics , astronomy , composite material
This article investigates the excited and charged states of three branched oligothiophenes with methyl–thienyl side groups as models to promote 3D arrangements. A comparison with the properties of the parent systems, linear all‐α,α‐oligothiophenes, is proposed. A wide variety of spectroscopic methods (i.e., absorption, emission, triplet–triplet transient absorption, and spectroelectrochemistry) in combination with DFT calculations have been used for this purpose. Whereas the absorption spectra are slightly blueshifted upon branching, both the emission spectra and triplet–triplet absorption spectra are moderately redshifted; this indicates a larger contribution of the β‐linked thienyl groups in the delocalization of the S 1 and T 1 states rather than into the S 0 state. The delocalization through the α,β‐conjugated path was found to be crucial for the stabilization of the trication species in the larger branched systems, whereas the linear sexithiophene homologue can only be stabilized up to the dication species.