Ultrafast Spectroscopy of Chromophores
Abstract
The synthesis of a family of symmetric 2,5-didodecanoxy phenyleneethynylene oligomer series bearing butadiynes as central group was carried out by a Sonogashira-Heck reaction by either the Pd(0)/CuI cross-coupling reaction between a bis(dodecanoxy)benzene halogenate terminated and a bis(dodecanoxy)benzene acetylene terminated oligomer or through self-coupling of bis(dodecanoxy)phenyle acetylene terminated oligomers. The electron-donator character of the dodecanoxy chains favors the acetylene-acetylene coupling in quantitative yields, while in the cross-coupling of acetylenes with iodo or bromo-aryls reaction by the Pd/CuI-catalyzed Sonogashira-Heck the reaction yields are rather modest. The molecular structure was confirmed by H1, DEPT-135, APT C13, COSY, HETCOR and by MALDI-TOF mass spectrometry. The optical properties in solution are quite similar to those of the respective (dodecanoxy) phenyleneethynylenes with high quantum yields with the exception of the dimer due to the fact that it is in reality a biphenylbutadiyne. The two photon absorption spectra in chloroform behave according to a three-level model where the conjugation signature, S, depends on the number of pi electrons, N, according to the law: S=ANk with K=4.3. This value is consistent with strong conjugation resulting from a rod-like shape to the oligomers.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 31, 2012
- Accession Number
- ADA566311
Entities
People
- Eduardo Arias
- Ivana Moggio
- Ronald F. Ziolo