36284-12-5Relevant academic research and scientific papers
2,7-substituted hexafluoroheterofluorenes as potential building blocks for electron transporting materials
Geramita, Katharine,McBee, Jennifer,Tilley, T.Don
supporting information; experimental part, p. 820 - 829 (2009/06/20)
A series of 2,7-substituted hexafluoro-9-heterofluorenes was synthesized via nucleophilic aromatic substitution (SNArN) reactions of phenyllithium, thienyllithium, and lithium phenylacetylide with various octafluoroheterofluorenes and 2,2'-dibromooctafluorobiphenyl. These compounds are of interest as possible building blocks for materials with useful electron transport properties, since they possess relatively low LUMO energy levels. The HOMO-LUMO energy gaps, as determined by UV-vis spectroscopy, range between 3.0 and 3.9 eV, while photoluminescence emission spectra reveal λ ems values in the range of 365 to 420 nm (corresponding to ultraviolet to violet/blue emission). Dilute solution state quantum yields vary significantly with the nature of the heteroatom and the 2,7-substituents, and approach unity for a number of the di(phenylethynyl) derivatives. The experimentally determined LUMO energy levels (- 2.7 to - 3.3 eV as determined by differential pulse voltammetry) suggest that these compounds may be good candidates for electron transport applications. Single-crystal X-ray analyses of a number of compounds revealed cofacial packing in all cases, with intermolecular distances as short as 3.4 A.
