The NMR spectra of blue series compounds B1, B2, B3 and B4 display interesting features. In B1 the six protons attached to Bodipy display unique (slightly broadened) signals in the 1 H-NMR and nine distinct C signals for the Bodipy unit plus three signals for the propyl chain. Based on this observation, the C-N(propyl) bond appears to have significant double bond character with inhibited rotation, decreasing the symmetry of the molecule and leading to two different Bodipy sides. In B2 this partial double bond character appears to be reduced (probably due to the slightly electron-richer Bodipy unit due to the two electron-releasing methyl groups) since fewer signals in the C-NMR are observed, some of which are severely broadened. In B3 and B4 the alkyl groups on both sides of the N-propyl chain prevent the planarization of the propyl nitrogen atom and a symmetric NMR spectrum is observed.