Monophasic solid solutions with asymmetrical pyrrolo-(4-3-c)-pyrroles as host

Uni-phase solid solutions comprise 60-90 mole-% asymmetric 2, 5-dihydro-1, 4-diketopyrroloÄ3, 4-cÜpyrrole of formula (I) and 40-10 mole-% 2, 5-dihydro-1, 4-diketopyrroloÄ3, 4-cÜpyrrole of formula (IIa) or quinacridone of formula (IIb). G1, G2 = unsubstituted phenyl, 3- or 4-pyridyl or naphthyl, or a group of formula (IIIa-IIIe); in which R1, R2 = F, Cl, Br, CN, NO2, CF3, 1-8 C alkyl, 5-6 C cycloalkyl, phenyl, 1-8 C alkoxy(carbonyl), mono- or di-(1-8 C alkyl)amino(carbonyl) or morpholino; R3 = -O-, -NR5-, -N=N- or -SO2-; R4 = H, F, Cl, Br, CN, NO2, CF3, 1-8 C alkyl, 1-8 C alkoxy(carbonyl) or mono- or di-(1-8 C alkyl)-amino(carbonyl); R5 = H, Me or Et; or but if one of G1 and G2 = unsubstituted phenyl or 3- or 4-pyridyl, the other is not unsubstituted phenyl, 3- or 4-pyridyl or a (IIIa) or (IIIb) group with (a) R2 = Cl and R1 = H, F or CF3, (b) R1 = Cl and R2 = F or CF3 or (c) R1, R2 = F, M e or CF3; G3, G4 = an unsubstituted phenyl or 3- or 4-pyridyl group or a group of formula (IIIa) or (IIIb) in which R1, R2 = F, Cl, CN, NO2, CF3, 1-4 C alkyl, 1-4 C alkoxy or mono- or di-(1-4 C alkyl)-amino; R9 = H, halogen, 1-4 C alkyl or 1-4 C alkoxy. Also claimed is a composition containing the solid solution and a high molecular organic material. Preferably the solid solution contains 75-90, especially 75-84 mole-% (I) and 25-10, especially 25-16 mole-% (IIa) or (IIb). It may be subjected to thermal treatment or recrystallised after it has been prepd.