INTERNET ADVERTISING company DoubleClick, New York, is reportedly in negotiations to buy SmartBase, a catalog cooperative database wholly owned by Acxiom Corp., for a price estimated at $5 million. The negotiations come on the heels of widely publicized privacy concerns over DoubleClick’s November purchase of data warehouse company Abacus Direct Corp. for $1.7 billion. Abacus operates the Alliance catalog cooperative database, which has 1,200 members. Smart-Base was created by Direct Media Inc. in 1995.