The present invention relates to compounds of the formula I

##STR00001##

wherein X.sup.1, X.sup.2 are O or C(CN).sub.2; A is selected from

##STR00002##

wherein, if present, X.sup.3, X.sup.4 are O or C(CN).sub.2 and m, R.sup.4a, R.sup.4b, R.sup.5a, R.sup.5b, R.sup.6a, R.sup.6b, R.sup.6c, R.sup.6d, R.sup.7a, R.sup.7a, R.sup.8a, R.sup.8b, R.sup.9, R.sup.10a, R.sup.10b, R.sup.m1, R.sup.m2, R.sup.m3 and R.sup.m4 are as defined in the claims and description. The present invention also relates to a method for their preparation and their use as semiconductors, in particular as semiconductors in organic electronics and organic photovoltaics.

An object of the present invention is to provide a cMLCK activator that can enhance myocardial contractility without an increase in cellular calcium concentration. This object is achieved by a cMLCK activator containing an 8-hydroxyquinoline compound represented by the following formula (I) or a pharmaceutically acceptable salt thereof, or a solvate thereof,

##STR00001## wherein R.sup.1 represents hydrogen or the like; R.sup.2 represents R.sup.7CO (R.sup.7 is C.sub.1-6 alkyl or the like) or the like; R.sup.3 represents hydrogen; and R.sup.4, R.sup.5, and R.sup.6 represent hydrogen or the like.

An object of the present invention is to provide a cMLCK activator that can enhance myocardial contractility without an increase in cellular calcium concentration. This object is achieved by a cMLCK activator containing an 8-hydroxyquinoline compound represented by the following formula (I) or a pharmaceutically acceptable salt thereof, or a solvate thereof,

##STR00001## wherein R.sup.1 represents hydrogen or the like; R.sup.2 represents R.sup.7CO (R.sup.7 is C.sub.1-6 alkyl or the like) or the like; R.sup.3 represents hydrogen; and R.sup.4, R.sup.5, and R.sup.6 represent hydrogen or the like.