Pentamethine cyanine fluorescent dyes, preparation methods and uses thereof
A pentamethine cyanine fluorescent dye having the general formula I, a synthetic method and a use thereof are disclosed. In the general formula, X is CHO or CHCR 3 R 4 ; R 1 and R 2 are independently selected from the group consisting of (CH 2 ) n R 7 and et al.; R 3 and R 4 are independently selected from the group consisting of CN, COOH and COOR 16 ; R 5 , R 6 and R 7 are independently selected from the group consisting of H, SO 3 R 10 and COOR 11 ; R 8 is H or C 1-18 alkyl; R 9 is H or CH 3 ; R 10 is N(R 12 R 13 R 14 R 15 ); R 11 is C 1-18 alkyl; R 12 , R 13 , R 14 , R 15 and R 16 are independently selected from the group consisting of H, C 1-18 alkyl, (CH 2 ) m OR 8 and (CHR 9 CH 2 O) p R 8 ; Y − is halogen anion or OTs − ; and n, m and p are integers of 0-18. The dye can be utilized to sensitively detect viscosity of micro-environment such as tissues and cells.
1. A pentamethine cyanine fluorescent dye of formula I:
wherein
X is CHO or CHCR 3 R 4 ;
R 1 and R 2 are independently selected from the group consisting of (CH 2 ) n R 7 , (CH 2 ) m OR 8 , (CHR 9 CH 2 O) p R 8 and CH 2 C 6 H 4 R 7 ;
R 3 and R 4 are independently selected from the group consisting of CN, COOH and COOR 16 ;
R 5 , R 6 and R 7 are independently selected from the group consisting of H, SO 3 R 10 and COOR 11 ;
R 8 is H or C 1-18 alkyl;
R 9 is H or CH 3 ;
R 10 is N(R 12 R 13 R 14 R 15 );
R 11 is C 1-18 alkyl;
R 12 , R 13 , R 14 , R 15 and R 16 are independently selected from the group consisting of H, C 1-18 alkyl, (CH 2 ) m OR 8 and (CHR 9 CH 2 O) p R 8 ;
Y− is halogen anion or OTs−; and
n, m and p are integers of 0-18.
2. The compound according to claim 1 , wherein R 3 and R 4 are CN.
3. The compound according to claim 1 , wherein R 1 and R 2 are independently selected from (CH 2 ) n R 7 .
4. The compound according to claim 1 , wherein R 5 and R 6 are H.
5. The compound according to claim 2 , wherein R 1 and R 2 are CH 3 , R 5 and R 6 are H.
6. A synthesis method of the compound according to claim 1 , comprising the following steps:
(1) 2,3,3-trimethyl-3H-indole with a substituent group of R 5 is reacted with R 1 CH 2 Z to obtain a quaternary ammonium salt II, wherein Z is halogen or OTs, Z− is halogen anion or OTs−, reaction temperature is 80-148° C., reaction time is 6-12 hours, reaction solvent is selected from the group consisting of toluene, ortho-dichlorobenzene, ethanol and acetonitrile, and molar ratio of the indole compound to R 1 CH 2 Z is 1:1-1:4;
(2) 2-bromoacetic acid is reacted with POCl 3 and DMF to obtain an intermediate III with multi aldehyde groups, wherein molar ratio of 2-bromoacetic acid to POCl 3 is 1:4-1:6, and reaction temperature is 70±2° C.;
(3) the quaternary ammonium salt II obtained in the step (1) and the intermediate III obtained in the step (2) are refluxed for 2-6 hours in ethanol solvent with pyridine as a catalyst to obtain a pentamethine cyanine fluorescent dye of formula IV with aldehyde group at central position, wherein when molar ratio of the intermediate III to the quaternary ammonium salt II is 1:3, the product is a symmetrical pentamethine cyanine fluorescent dye with aldehyde group at the central position, while when two kinds of the quaternary ammonium salts are used, and molar ratio of the intermediate III, the first quaternary ammonium salt and the second quaternary ammonium salt is 1:0.8-1:1-3, the product is an asymmetrical pentamethine cyanine fluorescent dye with aldehyde group at the central position;
(4) the compound IV obtained in the step (3) is reacted with NaBH 4 in methanol to obtain a compound V;
(5) the compound V obtained in the step (4) is reacted with R 3 CH 2 R 4 under basic condition to obtain a compound VI, wherein reaction solvent is anhydrous methanol, reaction temperature is 25-40° C., and molar ratio of the compound V to R 3 CH 2 R 4 is 1:2-1:4;
(6) the compound VI obtained in the step (5) is oxidized and dehydrogenated to obtain a compound VII, wherein solvent is dichloromethane or chloroform, oxidation-dehydrogenation reagent is 2,3,5,6-tetrachloro-1,4-p-benzoquionone or 2,3-dichloro-5,6-dicyano-1,4-p-benzoquionone, and molar ratio of the compound V to the oxidation-dehydrogenation reagent is 1:0.5-1:1;
(7) ion exchange is performed between the compounds IV and VII with a sodium salt or a potassium salt containing Y− anion to obtain the compound of formula I.
7. A method for detecting fluid viscosity, comprising:
introducing a compound of claim 1 into a fluid;
measuring a fluorescence intensity or a fluorescence lifetime of the fluid obtained in step (1);
correlating a change in the fluorescence intensity or the fluorescence lifetime to a change in the fluid viscosity.
8. The compound according to claim 2 , wherein R 1 and R 2 are independently selected from (CH 2 ) n R 7 .
9. The compound according to claim 2 , wherein R 5 and R 6 are H.
10. The method of claim 7 , wherein the fluid is an intracellular fluid.