Use of a compound of formula (I) wherein R1 and R2 are selected independently from each other from C1-C10 alkyl, which may be substituted by one or more F, or wherein R1 and R2 are linked and jointly selected from C2-C3 alkanediyl forming together with the group -OPO- a five- or six-membered heterocycle which may be substituted by one or more substituents selected from F and optionally fluorinated C1-C10 alkyl, as gelling agent in an aprotic organic solvent or solvent mixture.