The invention relates to compounds of formula (I): ##STR00001## wherein: B represents a hydrogen atom, a COOR group, a CONRR' group, or a (C.sub.1 C.sub.6)alkyl group substituted by a COOR, CONRR' or OR group, G.sub.1 represents a --X'--(CH.sub.2).sub.n--X--(CH.sub.2).sub.m--X''-- chain wherein X, X', X'', n and m are as defined in the description, Cy represents a grouping of formula (II) or (III): ##STR00002## G.sub.2 represents an alkylene chain as defined in the description, and A represents a NRCOR', NRCSR', CONRR', CSNRR', NRCONR'R'' or NRCSNR'R'' group.