Efficient Synthesis, Characterization, Single‐ Crystal XRD and Photophysical Properties of Rhodacyanine Dyes

ABSTRACT

This work describes an efficient synthesis of rhodacyanine dyes, derived from pharmacophoric precursors containing an ethyl‐substituted rhodanine moiety and a thiazole ring. All compounds were fully characterized by ¹ H‐NMR, ¹³ C‐NMR, FT‐IR, and HRMS. Single‐crystal x‐ray diffraction was employed to elucidate their structure, revealing the geometry of their double bonds and unambiguously proving that they were obtained as a single isomer. Structural analysis revealed that that these compounds crystallize in the monoclinic (P21/n, P21/c) and orthorhombic (Pcca) space groups. Finally, their absorption and emission properties were investigated in solution, showing that the introduction of a pyridinium ring induces a bathochromic shift by improving the push‐pull characteristics of the dyes. The other substituents have little influence on these properties.