abstract |
There is provided a compound of formula I:n n n Formula In n n n n n n n In Formula I,n n n One of R 1 and R 2 is of the formula Is a group of wherein R 4 is selected from H and hydrocarbyl, R 5 is a hydrocarbyl group, and L is any binding group, or R 1 and R 2 together are a group To form a ring substituted byn n n R 3 is H or a substituent,n n n X is S, O, NR 6 and C (R 7 ) (R 8 ), wherein R 6 is selected from H and hydrocarbyl groups, and R 7 and R 8 are each independently selected from H and hydrocarbyl groups ). |