Mesobiliverdin IXα diesters of α,ω-dialkanols were obtained by reaction of mesobiliverdin IXα dicesium salt with diiodomethane, 1,3-dibromopropane and 1,4-dibromobutane. Mesobiliverdin IXα methylene diester was tested and compared to mesobiliverdin IXα dimethyl ester, for their photoisomerization behaviour, addition of nucleophiles at C10, protonation, and deprotonation. The constriction imposed by the internal cycle to the flexibility around the two central rings has no appreciable effect on these reactions. In fact, the small pK a differences in the protonation indicate that previous results, on the protonation of biliverdins bridged between the end rings, can be explained through a stretched structure of the protonated bile pigment implying a change in the configuration or conformation of one end ring.