Fluorinated voltage sensitive dyes, preparation thereof, and optical methods of use
A fluorinated voltage sensitive dye has the structure wherein p is 0, 1, or 2; X q− is an anionic counterion having a charge, q, that is 1 or 2; n is 1 or 2; R 1 is an optionally substituted C 1 -C 12 , alkyl; R 2 is hydrogen, and R 3 is hydrogen or fluorine; or R 2 and R 3 collectively form a divalent —CH═CH—CH═CH— group; R 4 and each occurrence of R 5 are each independently hydrogen or fluorine; R 6 is hydrogen or fluorine or trifluoromethyl; and each occurrence of R 7 is independently C 1 -C 6 alkyl; provided that the dye comprises at least one fluorine atom. The dye is particularly useful for monitoring the dynamics of action potentials in axons and/or dendrites.
1. A fluorinated voltage sensitive dye having the structure
wherein
p is 0, 1, or 2; X q− is an anionic counterion having a charge, q, that is 1 or 2;
n is 1 or 2;
R 1 is an optionally substituted C 1 -C 12 alkyl;
R 2 is hydrogen, and R 3 is hydrogen or fluorine; or R 2 and R 3 collectively form a divalent —CH═CH—CH═CH— group;
R 4 and each occurrence of R 5 are each independently hydrogen or fluorine;
R 6 is hydrogen or fluorine or trifluoromethyl; and
each occurrence of R 7 is independently C 1 -C 6 alkyl;
provided that at least one of R 3 , R 4 or R 6 is fluorine, or at least one occurrence of R 5 is fluorine.
2. The fluorinated voltage sensitive dye of claim 1 , wherein X q− is Br − .
3. The fluorinated voltage sensitive dye of claim 1 , wherein n is 2, and each occurrence of R 5 is hydrogen.
4. The fluorinated voltage sensitive dye of claim 1 , wherein n is 1.
5. The fluorinated voltage sensitive dye of claim 1 , wherein n is 2.
6. The fluorinated voltage sensitive dye of claim 1 , wherein R 1 is selected from the group consisting of —CH 2 CH(OH)CH 2 N + (CH 3 ) 2 (CH 2 CH 2 OH), —(CH 2 ) 3 SO 3 − , —(CH 2 ) 4 SO 3 − , —(CH 2 ) 3 —N + (R 8 ) 3 wherein each occurrence of R 8 is independently C 1 -C 6 alkyl, and —(CH 2 ) 2 —N + (R 9 ) 3 wherein each occurrence of R 9 is independently C 1 -C 6 alkyl.
7. The fluorinated voltage sensitive dye of claim 1 , wherein R 1 is —(CH 2 ) 3 —N + (R 8 ) 3 wherein each occurrence of R 8 is independently C 1 -C 6 alkyl.
8. The fluorinated voltage sensitive dye of claim 1 , wherein R 2 and R 3 are hydrogen.
9. The fluorinated voltage sensitive dye of claim 1 , wherein R 2 is hydrogen and R 3 is fluorine.
10. The fluorinated voltage sensitive dye of claim 1 , wherein R 2 and R 3 collectively form a divalent —CH═CH—CH═CH— group.
11. The fluorinated voltage sensitive dye of claim 1 , wherein R 4 is hydrogen.
12. The fluorinated voltage sensitive dye of claim 1 , wherein n is 1, and R 5 is hydrogen.
13. The fluorinated voltage sensitive dye of claim 1 , wherein n is 1, and R 5 is fluorine.
14. The fluorinated voltage sensitive dye of claim 1 , wherein n is 2, and one occurrence of R 5 is hydrogen and the other occurrence of R 5 is fluorine.
15. The fluorinated voltage sensitive dye of claim 1 , wherein each occurrence of R 7 is ethyl, or each occurrence of R 7 is n-butyl.
16. The fluorinated voltage sensitive dye of claim 1 , wherein the dye comprises no more than four fluorine atoms.
17. The fluorinated voltage sensitive dye of claim 1 , wherein the dye comprises four fluorine atoms.
18. The fluorinated voltage sensitive dye of claim 1 , wherein the dye comprises three fluorine atoms.
19. The fluorinated voltage sensitive dye of claim 1 , wherein the dye comprises two fluorine atoms.
20. The fluorinated voltage sensitive dye of claim 1 , wherein the dye comprises one fluorine atom.
21. The fluorinated voltage sensitive dye of claim 1 ,
wherein
pX q− is 2Br − ;
n is 1;
R 1 is —(CH 2 ) 3 —N + (CH 2 CH 3 ) 3 ;
R 2 , R 3 , R 4 , and R 5 are hydrogen;
R 6 is fluorine; and
each occurrence of R 7 is ethyl, or each occurrence of R 7 is n-butyl.
22. The fluorinated voltage sensitive dye of claim 1 , selected from the group consisting of
23. The fluorinated voltage sensitive dye of claim 1 , selected from the group consisting of
24. A method of forming a fluorinated voltage sensitive dye, the method comprising:
reacting a 1-(optionally substituted C 1 -C 12 alkyl)-4-methylpyridinium compound and a 6-dialkylaminonaphthalene-2-carboxaldehyde to form the fluorinated voltage sensitive dye;
wherein the 1-(optionally substituted C 1 -C 12 alkyl)-4-methylpyridinium compound has the structure
wherein p is 0, 1, or 2; X q− is an anionic counterion having a charge, q, that is 1 or 2; R 1 is an optionally substituted C 1 -C 12 alkyl; R 2 is hydrogen, and R 3 is hydrogen or fluorine; or R 2 and R 3 collectively form a divalent —CH═CH—CH═CH— group; and R 4 is hydrogen or fluorine;
wherein the 6-dialkylaminonaphthalene-2-carboxaldehyde has the structure
wherein n is 1 or 2; each occurrence of R 5 is independently hydrogen or fluorine; R 6 is hydrogen or fluorine or trifluoromethyl; and each occurrence of R 7 is independently C 1 -C 6 alkyl; and
wherein the fluorinated voltage sensitive dye is the fluorinated voltage sensitive dye of claim 1 .