Abstract: A composition for coating comprising at least one compound of formula I and optionally at least one compound of formula II RaSi(R1)n(X1)3-n??I RbSi(R2)m(X2)3-m??II wherein Ra is a straight-chain or branched C(1-24) alkyl group, Rb is an aromatic group, such as an optionally substituted carbocyclic and heterocyclic group comprising five-, six- or ten-membered ring systems, which is linked by a single covalent bond or a spacer unit, such as a straight-chain or branched alkyl residue having 1 to 8 carbon atoms, to the Si— atom, R1 and R2 are independently of each other a lower alkyl group, such as a straight chain and branched hydrocarbon radical having 1 to 6 carbon atoms, X1 and X2 are independently of each other a hydrolysable group, such as a halogen or an alkoxy group and n, m are independently of each other 0 or 1, with the proviso that if n and m are independently of each other 0 or 1, X may represent the same or different groups.