| abstract |
A compound having formula (Ph3C)mAr(GR)n, wherein Ph represents a phenyl group, Ar is an aromatic ring system having from six to twenty carbon atoms; G is O, S, SO or SO2; R is: (a) C1-C18 alkyl substituted by at least one of OH, SH, C1-C18 alkoxy and cyano; or (b) C4-C18 heteroalkyl; m is one or two; and n is an integer from one to four. |