This invention relates to a new compound represented by formula (I). Particularly, the new compound is used as an additive in copper electroplating. A chemical structure for the leveler, an electroplating bath containing the same, a method of preparing the additive and a method of electroplating a substrate with the electroplating bath containing the additive are disclosed. The additive compound/molecule of the present invention provides a branched structure at each ends, wherein each of the branches comprises a positively charged nitrogen moiety. The additive compound/molecule is formed by linking the branches having the positive charged nitrogen moieties to the backbone of the additive compound/molecule. This leads to a high charge density novel additive compound/molecule.