TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Disclosed): Preparation of compound (I) involves brominating pyrrolopyrrole derivative of formula (ia) using N-bromo-succinimide to give corresponding bromide derivative which on side chain-elongation using Ar2-H, Ar5-H, Ar3-R3, and Ar6-R4 and palladium catalyst gives (I). Full Definitions:    T1=-(Ar4)d-(Ar5)e-(Ar6)f-(Ar8)h-R4;    T2=-(Ar1)a-(Ar2)b-(Ar3)c-(Ar7)g-R3;    R1 and R2=H, 1-100C alkyl, -COOR103, 1-100C alkyl (which is substituted by at least one halo, hydroxyl, nitro, -CN, or 6-24C aryl and/or interrupted by -O-, -COO-, -OCO-, or -S-); 7-100C arylalkyl, carbamoyl, 5-12C cycloalkyl (optionally mono to tri substituted with 1-8C alkyl and/or 1-8C alkoxy, 6-24C aryl, particularly phenyl or 1- or 2-naphthyl (optionally mono to tri substituted with 1-8C alkyl, 1-8C thioalkoxy, and/or 1-8C alkoxy, or pentafluorophenyl);    R103=H, 6-24C aryl (optionally substituted by 1-25C alkyl, or 1-25C alkoxy); or 1-50C alkyl (optionally substituted by -O-, especially 4-25Calkyl);    a=1-3;    d=0-3;    Ar1 and Ar4=bivalent group of the formula (II);    X3 and X4=N, CR100, or an annulated (aromatic) heterocyclic ring system (containing at least one thiazole ring, which may be optionally substituted by at least one group);    R100=H, 1-25C alkyl, 1-18C alkoxy, 6-24C aryl, 7-25C aralkyl, or heteroaryl;    b, c, e, f, g and h=0-3;    Ar2, Ar3, Ar5-Ar8=Ar1, or group of formulae (III)-(X);    X=SiR60R61, NR62, CR10R11, -S-, or -O-;    p=0-2;    R5=aliphatic hydrocarbon (having up to 25C) or 1-25C alkoxy;or    R5+R5=7C alkylene or alkenylene;    R6, R7, R9, R12-R19, and R21=1-25C alkyl, 1-25C alkoxy, 6-24C aryl, 7-25C aralkyl, or heteroaryl;or    R6+R7=25C alkylene or alkenylene (which may be both bonded via oxygen and/or sulfur to the thienyl residue);    R10 and R11=H, 1-25C alkyl, 7-25C aralkyl, 6-24C aryl, heteroaryl;or    R10+R11=oxo or form a five or six membered ring (which is optionally substituted by a) 18C aliphatic hydrocarbon, b) 1-18C alkoxy or 2-18C alkylenedioxy (in both of which carbon atoms which are not adjacent to oxygen may be replaced by oxygen), or c) 6-24C aryl, 7-25C aralkyl, heteroaryl, 3-12C cycloalkyl or 4-12C cycloalkyl-alkyl;    R60 and R61=H, 1-25Calkyl, phenyl, (especially 1-12C alkyl);    R62=H, 7-25C arylalkyl, 6-24C aryl; 6-24C aryl (which is substituted by 1-25C alkyl, 1-25C perfluoroalkyl, or 1-25C alkoxy); 1-25C alkyl (optionally which is interrupted by -O-, or -S-); or -COOR103 (especially 1-25C alkyl);    R3 and R4=H, 25C aliphatic hydrocarbon, 25C alkoxy or alkenyloxy, halo, a cycloaliphatic, cycloaliphatic-aliphatic, aromatic, aromatic-aliphatic, 25C heteroaromatic or 25C heteroaromatic-aliphatic group, or group of formulae (XI)-(XIX) or -(BU')w-N(A3)-A'3;    w=0, or 1;    BU'=bridging unit;    A3 and A'3=6-24C aryl, or a 2-26C heteroaryl group (which can optionally be substituted);    R22-R58=H, 25C aliphatic hydrocarbon, 25C alkoxy or 25C alkenyloxy, halo, a cycloaliphatic, cycloaliphatic-aliphatic, aromatic, aromatic-aliphatic, 25C heteroaromatic or 25C heteroaromatic-aliphatic group;or    R27+R28, or R27+R58=25C alkylene or 25C alkenylene (which may be both bonded via oxygen and/or sulfur to the thienyl residue).    Provided that:    (1) e is not 0 if d is 0;    (2) the compound (I) excludes compound 3,6-bis-benzothiazol-2-yl-2,5-dihydro-pyrrolo(3,4-c)pyrrole-1,4-dione.    SPECIFIC COMPOUNDS - 54 Compounds are specifically claimed as (I) e.g. 2,5-bis(2-hexyldecyl)-3,6-di(thiazol-2-yl)pyrrolo(3,4-c)pyrrole-1,4(2H,5H)-dione (Ia); 2,5-dioctadecyl-3-(thiazol-2-yl)-6-(thiophen-2-yl)pyrrolo(3,4-c)pyrrole-1,4(2H,5H)-dione; 2-heptyl-5-hexyl-3,6-bis-thiazol-5-yl-2,5-dihydro-pyrrolo(3,4-c)pyrrole-1,4-dione; 2,5-bis-(3-phenyl-propyl)-3,6-bis-(2-thiophen-2-yl-thiazol-5-yl)-2,5-dihydro-pyrrolo(3,4-c)pyrrole-1,4-dione; and 3,6-bis-(2-(4-butyl-thiophen-2-yl)-thiazol-5-yl)-2,5-bis-(2-hexyl-decyl)-2,5-dihydro-pyrrolo(3,4-c)pyrrole-1,4-dione.    EXAMPLE - A mixture of iron trichloride (FeCl3) (5 mg), sodium (2.6 g) and t-amylalcohol (100 ml) was heated to 110 degrees C for 20 minutes before a mixture of the thiazole-2-nitrile (5 g) and di-tert-amyl succinate (8.25 g) was added drop wise. The reaction mixture was stirred at 110 degrees C for 3 hours to give 1,4-diketopyrrolo(3,4-c)pyrrole (DPP) (5.2 g) as dark blue powder. The solution of 1,4-diketopyrrolo(3,4-c)pyrrole (DPP) (4 g), potassium hydroxide (2.9 g) in water (3 ml) and 1-bromo-2-hexyl-decyl (18.5 g) in N-methyl- pyrrolidone (NMP) (50 ml) was heated to 140 degrees C for 6 hours to give 2,5-bis(2-hexyldecyl)-3,6-di(thiazol-2-yl)pyrrolo(3,4-c)pyrrole-1,4(2H,5H)-dione (Ia) (0.4 g) as blue solid.