[in formula (6???) and (7???), each of X1 to X10 independently represents H or a protonic acid group; each of B1 to B3 independently represents a direct bond, ???C(CF3)2???, ???SO2???, ???CO???, or a group represented by the formula: ???CH(CxHx+1){C(CyHy+1)(Cy???Hy???+1)}??{C(CzHz+1)(Cz???Hz???+1)}?????, wherein x is an integer of 0 to 9, each of y, y???, z and z??? is independently an integer of