Über die Konformation eines trinuclearen [1.1.1]Tetramethinium-Cyaninfarbstoffs mit Indolin-Endgruppen

Conformation of a Trinuclear [1.1.1]Tetramethinium Cyanine Dye with Indoline End Groups According to its ESCA spectrum (Figure 1) and an X-ray structural analysis (Figure 2), the [1.1.1]tetramethinium cyanine dye 2 exists in the crystalline state and probably also in solution as methinylogous propeller-like guanidinium ion 2a with approximate C3 symmetry, and not as vinylogous amidinium ion 2b corresponding to a linear β-substituted trimethine cyanine dye.