COc1ccc(/C=C2/SC(c3ccccc3)N(NC(=O)CCCCCCCCC(=O)NN3C(=O)/C(=C\c4ccc(OC)c(OC)c4)SC3c3ccccc3)C2=O)cc1OC
A lower number of pka indicates that the acid dissociates more entirely in water. What is pka of the molecule?