The effect of plasmonic enhancement on the two-photon absorption cross section of organic chromophores attached to polyelectrolyte-coated gold nanorods was investigated. The magnitudes of such enhancements were confirmed using single and two photon excitations of the chromophore molecules bound to polyelectrolyte-coated gold nanorods. By synthesizing two-, four-, six-, and eight-polyelectrolyte layer coated nanorods of a particular aspect ratio, the distance dependence of the evanescent electromagnetic field on molecular two-photon absorption was observed. Enhancements of 40-fold were observed for the chromophores nearest to the surface.
Covalent
organic frameworks (COFs) are an attractive class of crystalline,
porous materials because their reticular chemistry allows frameworks
to be synthesized in a predictable manner. As a result of this defining
characteristic, the past decades have witnessed considerable efforts
to demonstrate unique pore shapes and sizes; however, less attention
is often given to atomistic level structural changes. To further understand
the relationship of a COF’s structure and its unique properties,
this work provides a foundational study exploring the relationship
of structural isomer linkages in two COFs, TAPA–PDA COF and
IISERP-COF2. These imine-based COFs were extensively studied and compared
with respect to their synthetic conditions, framework properties,
phase reversibility, optical properties, and surface energy. Our results
suggest that compared to IISERP-COF2, the TAPA–PDA COF has
stronger phase change reversibility and significant red shifting of
the UV–vis absorption and fluorescence and exhibits hydrophilicity.
These findings provide evidence that careful consideration of monomer
pairs is necessary when designing materials because these minor structural
changes can lead to vastly diverging properties.
Ten methylated-meso-phenyl-BODIPY dyes with varying iodine content were synthesized and studied using experimental and theoretical methods to examine how iodine substitution and loading influence the excited-state dynamics of the chromophores.
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