Abstract: A compound having the following structure: wherein: R1, R2, R3, R4, R5, R6, R7, R8, R9, and R10 are independently selected from (i) hydrogen atom, (ii) hydrocarbon groups (R) containing 1-30 carbon atoms and optionally substituted with one or more fluorine atoms, (iii) —OR? groups, (iv) —NR?2 groups, (v) —C(O)R? groups, and (vi) halogen atoms, wherein R? groups are independently selected from R groups and hydrogen atoms, and wherein the R group optionally includes a C(O), ether, or amino linkage; Xm? is an anionic species with a magnitude of charge m, where m is an integer of at least 1; and n is a number, provided that n×m=1. Also described herein are methods for removing one or more oxyanions from a liquid source by use of the above compound or mono-pyridyl derivative thereof.