Patent ID: 8034800

Claim:
A compound of formula 1 or 2, A 1 -Ph (1) or A 1 -Ar-A 2 (2) wherein A 1 and A 2 are selected from formulae 4 and or a salt whereof; wherein Ar is selected from the group consisting of 1,2-phenyl, 1,3-phenyl and 1,4-phenyl optionally substituted with one or more methyl groups; each n is independently an integer from 0 to 1; m is 1; Ph is phenyl optionally functionalised with groups R 4 , wherein R 4 is selected from the group consisting of methyl, other C 1 to C 4 alkyl and fluorophores; and R 1 is selected from the group consisting of H, Me and linear chain C 2 -C 4 alkyl; with the proviso that when Ph is unsubstituted phenyl in formula 1 and A 1 is formula 4, R 1 is not Me.