SERS Characterization of the Indocyanine-Type Dye IR-820 on Gold and Silver Nanoparticles in the Near Infrared

Scheme 1

(a) Schematic chemical structure of IR-820; the rings are labeled A–G. (b) Schematic structure of IR-820 optimized using DFT with the hybrid functional B3LYP and 6-311G(d,p) basis-set. The grey spheres represent C, blue for N, red for O, yellow for S, green for Cl, and purple for Na. (c) MEP maps for IR-820 calculated at the same level of theory as for (b); red-to-blue color scheme indicates negative-to-positive partial charges.