Chalcogenopyrylium Dyes with Anchors to Nanoparticle and Semiconductor Surfaces
Bedics, Matthew Allen
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Surface enhanced Raman scattering (SERS) has gained widespread attention as a biomedical imaging technique due to its multiplexing capabilities and the low limits of detection (LODs) of SERS-nanoprobes. The library of available reporter molecules, which are used to generate unique SERS spectra, was previously limited to commercially available dyes or a small group of cyanine reporters. Herein, the design and synthesis of a novel group of chalcogenopyrylium SERS reporters is described. These dyes have a high affinity for Au and absorption maxima that range into the NIR region. These reporter molecules enabled the use of the 1280 nm laser, which was previously incompatible with SERS imaging. Also, nanoprobe LODs using these dyes as reporters are lower than any previously documented systems, with a 100 aM LOD using a 785 nm excitation and multiple examples of fM to pM LODs using a 1064 nm or 1280 nm excitation source. Nanoprobes functionalized with these compounds have also been successfully utilized in vivo, and produce more intense SERS spectra as compared to a commonly used cyanine reporter. Dye sensitized solar cells (DSSCs) have produced considerable interest as an alternative to conventionally used Si-based solar cells. Specifically, DSSCs that use metal-free organic dyes as sensitizers are important due to the lower cost and the use of earth abundant materials as starting materials. Herein, a group of chalcogenopyrylium dyes were appended with an anchoring group to TiO 2 , which enables the use of these dyes as sensitizers. Structural modifications were used to extend absorption maxima into the near-infrared region of the light spectrum and to evaluate the effect that dye aggregation has on device performance. The monomethine dyes successfully produced a photocurrent, with incident photon to current efficiency values as high as 20%. Aggregation was found to benefit these systems due to the spectral broadening of aggregated dyes, and consequent increased range of wavelengths that produce a photocurrent.