TECHNOLOGY FOCUS - POLYMERS - Preparation (disclosed): Benzamide compound of formula (20) is subjected to salt exchange reaction with carbonyl compound of formula: HOOC-A12-A2-C(=O)-CH2(-R12)=CH2 (21), ClOC-A12-A2-C(=O)-CH2(-R12)=CH2 (22) or O-(C(=O)-A12-A2-C(=O)-CH(-R12)=CH2)2 (23) to obtain aromatic aldehyde compound of formula (24). Aromatic aldehyde compound (24) is reacted with aniline derivative of formula (25) to obtain indole derivative (I).A11=1-6C alkylene optionally substituted by OH;A12=A1;andR12=A2.Preferred Composition: The polymer comprises a monomer unit derived from indole derivative (I), and monomer units derived from ester group-containing monomer of formula: H2C=C(-R21)(-COO-R22) (II), amide group-containing monomer of formula: H2C=C(-R30)(-CON(-R31)(-R32)) (III), alkene group-containing monomer of formula: H2C=C(-R21)(-R33) (IV) and cyclopentane-1,3-dione monomer of formula (V).R21=R12;R22=H, 1-18C alkyl, 1-10C hydroxyalkyl, 6-10C aryl, 7-13C aralkyl, 2-9C alkoxyalkyl, 7-13C aryloxyalkyl, 5-7C morpholinoalkyl, 3-9C trialkylsilyl, 6-10C alicyclic hydrocarbyl optionally containing oxygen, 3-9C dialkylaminoalkyl, 1-18C fluoroalkyl, 1-6C N-alkylenephthalimido, -(R23-O-)q-R24, -R28-N+(-R25)(-R27)-R26, or -(CH2)l-O-C(=O)-R29-C(=O)-OH;R23=1-3C alkylene;R24=phenyl (optionally substituted hydroxy), or 1-3C alkyl;q=1-3;R25-R27=1-3C alkyl;R28=1-3C alkylene;l=1-6;R29,R30=xylyl or phenyl;R31=H or 1-3C alkyl;R32=H, 1-3C alkyl, 3-9C diaminoalkyl or 1-6C hydroxyalkyl;or R31+R32+N=morpholino;R33=phenyl or pyrrolidino;R35=N or O;j=0 (when R35 is O) or 1 (when R35 is N);andR34=H, 1-20C alkyl, 1-10C hydroxyalkyl, 1-10C haloalkyl, 1-10C alkylcycloalkyl, 6-7C halocycloalkyl, or 6-10C aryl (optionally substituted by 1-6C alkyl) or 6-10C haloaryl. Preferred Definitions:    An-=tetrakis(perfluoro phenyl)borate anion.    EXAMPLE - 10 g 2-(1,3,3,-Trimethylindolin-2-ylidene) acetaldehyde, 6.8 g 2-(4-aminophenyl) ethanol and 50 mL acetic acid were added to round bottom flask provided with stirrer, reacted at 40 degrees C for 3.5 hours, methylene chloride and saturated salt solution were added, and organic layer was extracted. Then, the organic layer was washed with saturated sodium bicarbonate solution, concentrated and the solvent was distilled off to obtain 2-(4-(2-(1H-indol-2-yl)-ethylamino)-phenyl)-ethyl-2-(2-methyl-acryloyloxy)-ethylsuccinate. 2-(4-(2-(1H-indol-2-yl)-ethylamino)-phenyl)-ethyl-2-(2-methyl-acryloyloxy)-ethylsuccinate was reacted with lithium tetrakis (pentafluorophenyl) borate to obtain 2-(4-(2-(3,3-dimethyl-3H-indol-2-yl)-ethylamino)-phenyl)-ethanol.