Donor-Functionalized Polydentate Pyrylium Salts and Phosphinines: Synthesis, Structural Characterization, and Photophysical Properties

• Published in: Chemistry : a European journal Vol. 13; no. 16; pp. 4548 - 4559
• Main Authors: Müller, Christian, Wasserberg, Dorothee, Weemers, Jarno J. M., Pidko, Evgeny A., Hoffmann, Sandra, Lutz, Martin, Spek, Anthony L., Meskers, Stefan C. J., Janssen, René A. J., van Santen, Rutger A., Vogt, Dieter
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01-01-2007; WILEY‐VCH Verlag
• Subjects: Crystallography, X-Ray; density functional calculations; fluorescence; heterocycles; Models, Chemical; Models, Molecular; Molecular Structure; Organophosphorus Compounds - chemical synthesis; Organophosphorus Compounds - chemistry; phosphorescence; Photochemistry; Pyrans - chemical synthesis; Pyrans - chemistry; pyrylium salt; Stereoisomerism
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.200601650

A series of donor‐functionalized pyrylium salts have been prepared by classical condensation reactions which were further converted into the corresponding thienyl‐ and pyridyl‐substituted polydentate λ3‐phosphinines by reaction with P(SiMe3)3. Further chemical modification of these phosphorus heterocycles with Hg(OAc)2 in the presence of methanol resulted in the formation of λ5‐phosphinines. The photophysical properties of a selected series of thienyl‐ and pyridyl‐functionalized pyrylium salts, λ3‐ and λ5‐phosphinines, were investigated and the results compared and supported by theoretical calculations on the DFT level. Significant fluorescence was observed for the pyrylium salts and λ5‐phosphinines. In contrast, the heteroaromatic substituted λ3‐phosphinines show very little emission which is consistent with the low oscillator strength predicted by DFT calculations for this π→π* transition. Furthermore, all three classes of compounds show readily observable phosphorescence in solution, which was determined by time‐gated detection at low temperature.
A series of thienyl‐ and pyridyl‐functionalized λ3‐ and λ5‐phosphinines, such as depicted, have been prepared from the corresponding pyrylium salts and partially characterized crystallographically. Their photophysical properties, such as fluorescence and phosphorescence, have been measured and compared and supported by theoretical calculations on the DFT level.