In particular, the co-crystallization of SP withPOMs having a high-energy LMCT transition, as Mo8andMMo6, allows signicant shiing of the charge-transfer transi-tion near to the UV domain, limiting its fatal effect on the initialcolor of the samples, and so improving the photocolorationcontrast. Such a benecial association also prevents the strongoverlap between the POM and SP absorption bands whichcauses dramatic damage on the SP photoconversion rate