Agent: Hamilton, Brook, Smith & Reynolds, P.C.20080027048 - 2-phenylthiophene derivative: The present invention relates to a 2-phenylthiophene derivative or a salt thereof, wherein the thiophene ring is substituted with a carboxyl group or the like and the benzene ring has an electron-withdrawing group such as a cyano group and an electron-donating group such as a substituted alkoxy group at the..