20  US 9,217,919 B2  19  (III-5)  (III-6)  H  *---f-CH--Ct-*  I  I  C=O C=O  I  I  0  0  I  I  Ro19  Ro2  f 20  100  SO 3  1 -Ar3a  Ar4a  (IV-1)  H  *---f-CH--Ct-*  I  I  C=O C=O  I  I  0  N-Ro3  I  I  Ro19  Ro2  f 20  I  0 fis-Ar  SO$_{3 }$ 3a  (IV-2)  H  *---f-CH--Ct-*  I  I  C=O C=O  I  I  0  0  I  I  Ro19  Ro2  10  SO3  (IV-3)  H  *---f-CH--Ct-*  I  I  C=O C=O  I  I  0  N-Ro3  I  I  Ro19  Ro2  10  SO3  (IV-4)  (III-4)  Roi  I  *---f-CH2-Ct-*  I  C=O  I  Ro3-N  I  Ar2a  Ro2  I  I  0fiS-Ar3 0  SO3  I  Ar4a  (III-3)  Roi  I  *---f-CH2-Ct-*  I  C=O  I  0  I  Ar2a  Ro2  I  I  0fiS-Ar3 0  SO3  I  Ar4a  (III-2)  Roi  I  *--t-CH2 -Ct-*  I  Aria  I  Ar2a  Ro2  I  I  0fiS-Ar3 0  SO3  I  Ar4a  (III-1)  Examples of the repeating unit represented by any one of  the general formulae (III) to (V), which is effectively used in  the invention, include those represented by any one of the  following general formulae (III-1) to (III-6), general formu- lae (IV-1) to (IV-4) and general formulae (V-1) to (V-2),  respectively.  -continued 