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Super-Resolution Imaging of Clickable Graphene Nanoribbons Decorated with Fluorescent Dyes
The functional integration of atomically
defined graphene nanoribbons
(GNRs) into single-ribbon electronic device architectures has been
limited by access to nondestructive high-resolution imaging techniques
that are both compatible with common supports such as Si or Si/SiO<sub>2</sub> wafers and capable of resolving individual ribbons in dilute
samples. Conventional techniques such as scanning probe (AFM, STM)
or electron microscopy (SEM, TEM) have been restricted by requisite
sample preparation techniques that are incompatible with lithographic
device fabrication. Here we report the design and synthesis of ultralong
(∼10 μm) cove-type GNRs (cGNRs) featuring azide groups
along the edges that can serve as a universal handle for late-stage
functionalization with terminal alkynes. Copper-catalyzed click-chemistry
with Cy5 fluorescent dyes gives rise to cGNRs decorated along the
edges with fluorescent tags detectable by optical microscopy. The
structures of individual dye-functionalized cGNRs spin-coated from
a dilute solution onto transparent and opaque insulating substrates
were resolved using diffraction-limited fluorescence microscopy and
super-resolution microscopy (SRM) imaging techniques. Analysis of
SRM images reveals an apparent width of cGNRs in the range 40–50
nm and lengths in excess of 10 μm, the longest GNRs imaged to
date. Isolated cGNRs can even be distinguished from bundles and larger
aggregates as long as the center-to-center distance is greater than
the apparent width
Synthesis of Antioxidants for Prevention of Age-Related Macular Degeneration
Photooxidation of A2E may be involved
in diseases of the macula,
and antioxidants could serve as therapeutic agents for these diseases.
Inhibitors of A2E photooxidation were prepared by Mannich reaction
of the antioxidant quercetin. These compounds contain water-solubilizing
amine groups, and several were more potent inhibitors of A2E photooxidation
than quercetin