Fig. 1. DCBT structure. (a) Neutral |DA〉 and zwitterionic | and zwitterionic |D⁺A^–〉 resonance structures of merocyanine dye resonance structures of merocyanine dye DCBT. The polymethine chain connecting donor D and acceptor A is highlighted. (b) Molecular structure obtained from crystallographic analysis (thermal ellipsoids are set at 50% probability) (c) DFT calculations using IEFPCM solvation (in DMSO). The bond distances (in Å) along the polymethine chain are shown next to each bond.