A series of linear benzofuran
derivatives consisting of either
a vinylene or a cyanovinylene were prepared in order to investigate
their emission properties. The X-ray crystallography of structurally
similar derivatives was also evaluated. The crystalline structures
of the vinylene derivatives showed only lateral contacts that involved
the benzofurans and no π-stacking. In contrast, π-stacking
was observed for the bisbenzofuran and benzofuran-phenyl
cyanovinylene derivatives. No intermolecular π–π
stacking was observed for the extended cyanovinylene structures.
Intermolecular bonding between the nitrile and a furan atom
was found. The fluorescence quantum yields (Φ
fl
)
of the vinylene derivatives were consistently high (>50%) in both
solution and the crystal state. The exception was the benzofuran-furan-vinylene-phenyl,
the Φ
fl
of which was <10% when in the solid state.
The cyanovinylene counterparts emitted weakly in solution (Φ
fl
< 2%). Their luminogenic property was demonstrated with
a ca. 15-fold increase in emission in the solid state. A 6-fold emission
enhancement was also found when they were aggregated in a 90 vol%
methanol/water mixture. The solid-state emission enhancement of the
cyanovinylene benzofurans was in part attributable to
intermolecular contacts that suppressed excited-state deactivation
by molecular motion.
Light-emitting polymer nanotubes with tailored fluorescence emission bands have been prepared using organic emissive materials based on benzofuran, carbazole, and indolocarbazole scaffolds and investigated with the goal to obtain pure whitelight emission at the nanoscale. The polymer nanostructures were obtained by the anodic aluminium oxide (AAO) template method with PMMA as a transparent polymer matrix and a proficient choice of organic dyes emitting in the blue, green, yellow and red parts of the spectral range. It is demonstrated that combining aqueous dispersions of monochromatic nanotubes is an effective way of generating white light emission due to a simple correlation between the individual color components. Furthermore, it is also possible to target white emission at the nanoscale by adjusting the concentration of the dyes inside single nanotubes in order to obtain optimal color coordinates of ca. 0.3 in the CIE chromaticity diagram.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.