Tuning the Electronic Properties of Acetylenic Fluorenes by Phosphaalkene Incorporation
2016 (English)In: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 22, no 12, 4247-4255 p.Article in journal (Refereed) PublishedText
Versatile synthetic protocols for 2,7- and 3,6-diacetylenic fluorene-9-ylidene phosphanes (F9Ps) were developed. Protodesilylation of trimethylsilyl-protected acetylenic F9Ps affords terminal acetylenes that can be employed in Sonogashira and Glaser-type C-C coupling reactions to give thienyl-decorated and butadiyne-bridged fluorene-9-ylidene phosphanes, respectively. As evidenced by UV/Vis spectroscopy and cyclic voltammetry and corroborated by ab initio calculations, the presence of the P center in the F9Ps induces a significantly reduced HOMO-LUMO splitting that originates from stabilization of the LUMO levels. Variation of the acetylene substitution pattern is an additional tool to influence the optical and electronic properties. Whereas 3,6-disubstituted F9Ps have strong absorptions around 400nm, mainly due to -* transitions, 2,7-diacetylenic F9Ps exhibit longest-wavelength absorptions that have significant charge-transfer character with an onset around 520nm.
Place, publisher, year, edition, pages
2016. Vol. 22, no 12, 4247-4255 p.
alkynes, conjugation, electrochemistry, fluorenes, phospaalkenes
IdentifiersURN: urn:nbn:se:uu:diva-294322DOI: 10.1002/chem.201503430ISI: 000372526500041PubMedID: 26833389OAI: oai:DiVA.org:uu-294322DiVA: diva2:929380
FunderSwedish Research CouncilGöran Gustafsson Foundation for promotion of scientific research at Uppala University and Royal Institute of TechnologyLars Hierta Memorial Foundation, FO2014-0024Swedish Institute, 382/00386/2012