In an alternate embodiment, at least one of R1, R2, R3 and R5 is a solubilizing group which increases by 10 fold the solubility of the compound of formula I in water at 25??? C. as compared to the compound of formula I in the absence of said solubilizing group and X, Y and Z may all be other than N or at least one of X, Y or Z may be N.