Tuning the Optical Properties of 1,1'-Biphospholes by Chemical Alterations of the P-P Bridge
2014 (English)In: European Journal of Inorganic Chemistry, ISSN 1434-1948, E-ISSN 1099-0682, Vol. 2014, no 10, 1760-1766 p.Article in journal (Refereed) Published
2,5-Di(1-naphthyl)-1-phenylphosphole (2) was prepared from phenylphosphine and dinaphthylbutadiyne in 70% yield, and oxidized to its oxide 3. Treatment of 2 with a solution of potassium naphthalide results in selective formation of phospholide anion 4, which can be oxidized with iodine to afford biphosphole 5. The crystal structure of 5 exhibits an unusual s-trans conformation across the P-P bridge that is most stabilized by - stacking of the naphthyl substituents. Biphosphole 5 can be oxidized to its mono-oxidized 6 and dioxide 7. Generally, all phosphole oxidations lead to decreased pyramidalization of the P centres and, consequently, to significantly redshifted lowest-energy absorption maxima. Mono-oxidized biphosphole 6, which consists of an ordinary phosphole and an electron-deficient oxidized phosphole, features a unique low-energy optical transition (shoulder at 430 nm), which is tentatively assigned to a charge-transfer transition. The UV/Vis spectrum of dioxide 7 lacks this transition. At the same time, the emission maximum of 7 is bathochromically shifted by 80 nm relative to that of 5.
Place, publisher, year, edition, pages
2014. Vol. 2014, no 10, 1760-1766 p.
Phosphorus heterocycles, Charge transfer, Conjugation, Pi interactions, Aromaticity
IdentifiersURN: urn:nbn:se:uu:diva-224342DOI: 10.1002/ejic.201301376ISI: 000333486900023OAI: oai:DiVA.org:uu-224342DiVA: diva2:717048