Ladder oligo(m-aniline)s: derivatives of azaacenes with cross-conjugated π-systems.
J Org Chem
; 77(5): 2107-20, 2012 Mar 02.
Article
em En
| MEDLINE
| ID: mdl-22329511
ABSTRACT
We describe the synthesis and electronic properties of ladder oligomers of poly(m-aniline) that may be considered as derivatives of azaacenes with cross-conjugated π-systems. Syntheses of ladder oligo(m-aniline)s with 9 and 13 collinearly fused six-membered rings employed Pd-catalyzed aminations and Friedel-Crafts-based ring closures. Structures were confirmed by either X-ray crystallography or correlations between DFT-computed and experimental spectroscopic data such as (1)H, (13)C, and (15)N NMR chemical shifts and electronic absorption spectra. All compounds have planar "azaacene" moieties. The experimental band gaps E(g) ≈ 3.5-3.65 eV, determined by the UV-vis absorption onsets, were in agreement with the TD-DFT-computed vertical excitation energies to the S(1) state. Fluorescence quantum yields of up to 20% were found. Electrochemically estimated HOMO energies of -4.8 eV suggested propensity for a facile one-electron oxidation and just sufficient environmental stability toward oxygen (O(2)). For two oligomers with "tetraazanonacene" moieties, potentials of E(4+/3+) ≈ 1.6-1.7 V vs SCE were determined for four-electron oxidation to the corresponding tetraradical tetracations.
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Compostos de Anilina
Idioma:
En
Revista:
J Org Chem
Ano de publicação:
2012
Tipo de documento:
Article
País de afiliação:
Estados Unidos