| abstract |
A symmetric cyanine of the formula:n nwherein:n X is selected from the group consisting of O, S and C(CH 3 ) 2 ; W represents non-metal atoms required to form a benzo-condensednor a naphto-condensed ring; R 1 is selected from the group consisting of (CH 2 ) n CH 3 ,n(CH 2 ) n SO 3 - and (CH 2 ) n SO 3 H, wherein n is an integer selectednfrom 0 to 6 when R 1 is (CH 2 ) n CH 3 , and n is an integer selectednfrom 3 to 6 when R 1 is (CH 2 ) n SO 3 - or (CH 2 ) n SO 3 H; R 2 and R 3 are independently selected from the group consistingnof H, a sulphonic moiety and a sulphonate moiety; Q is selected from the group consisting of:n n n n n wherein q is 0 or 1 and D is selected from the group consistingnof:n -C≡C-G; n nand wherein A is O or S and G is, or contains a N, O or S nucleophilenmoiety or is, or contains a moiety capable of reactingnwith N, O or S nucleophiles. |