Pyrazole-based cyanine dye containing quaternary ammonium cation

1. A compound represented by the general formula [1] or a salt thereof:

wherein R 1 to R 6 each independently represent:

an alkyl group;

an alkyl group substituted by a group represented by the general formula [101]:

wherein R 101 to R 104 each independently represent a hydrogen atom or a C 1 to C 3 alkyl group and m represents an integer from 2 to 6, or two or three of R 102 to R 104 together with a nitrogen atom to which they are bound may form a heterocyclic ammonium cation;

an alkyl group substituted by a group represented by the general formula [2] and which optionally contains an amide bond:

—COOR 12   [2]

wherein R 12 represents a hydrogen atom, a C 1 to C 10 alkyl group, an alkali metal atom, an organic ammonium ion, or an ammonium ion or anion; or

an alkyl group substituted by a group represented by the general formula [3] and which optionally contains an amide bond:

—SO 3 R 13   [3]

wherein R 13 represents a hydrogen atom, an alkali metal atom, an organic ammonium ion, an ammonium ion or anion;

R 7 to R 10 each independently represent an alkyl group, an alkynyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylsulfonyl group, an arylsulfonyl group, an amino group, a group represented by the general formula [2], a group represented by the general formula [3], a halogen atom, a hydrogen atom, a hydroxyl group, a cyano group or a nitro group;

R 11 represents a hydrogen atom, an alkyl group, an alkynyl group or an aryl group, and n represents an integer from 0 to 3,

wherein at least one of R 1 to R 6 is an alkyl group substituted by a group represented by the general formula [101].

2. The compound according to claim 1 , wherein the compound represented by the general formula [1]is a compound represented by the following general formula [1′]:

wherein R 1a to R 6a each independently represent:

an alkyl group;

an alkyl group substituted by a group represented by the general formula [101];

an alkyl group substituted by a group represented by the general formula [2] ; or an alkyl group substituted by a group represented by the general formula [ 3 ],

R 8a is a group represented by the general formula [3],

R 11a represents an alkyl group, and

n represents an integer from 0 to 3,

wherein at least one of R 1a to R 6a is an alkyl group substituted by a group represented by the general formula [101]).

3. The compound according to claim 1 , wherein R 1 or R 2 is an alkyl group substituted by a group represented by the general formula [101].

4. The compound according to claim 1 , wherein the compound represented by the general formula [1] comprises 1 to 4 groups selected from a group consisting of a group represented by the general formula [3] and an alkyl group substituted by a group represented by the general formula [3].

5. The compound according to claim 4 , wherein the compound represented by the general formula [1] comprises 4 groups represented by the general formula [3].

6. The compound according to claim 1 , wherein R 8 is the group represented by the general formula [3], and either R 1 or R 2 , either R 3 or R 4 , and either R 5 or R 6 are an alkyl group substituted by the group represented by the general formula [3].

7. The compound according to claim 1 , wherein one of R 1 or R 2 is a C 1 to C 6 alkyl group substituted by a group represented by the general formula [101], and the other is a C 1 to C 5 alkyl group substituted by a group represented by the general formula [3].

8. The compound according to claim 1 , wherein R 101 is a hydrogen atom, and any one of R 102 to R 104 is a hydrogen atom and other two are alkyl groups.

9. The compound according to claim 1 , wherein the group represented by the general formula [101] is a N,N-dimethylammonioethylcarbamoyl group.

10. The compound according to claim 1 , wherein one of R 3 and R 4 is a C 1 to C 5 alkyl group substituted by a group represented by the general formula [3], and the other is a C 1 to C 6 alkyl group; and

one of R 5 and R 6 is a C 1 to C 5 alkyl group substituted by a group represented by the general formula [3], and the other is a C 1 to C 6 alkyl group.

11. The compound according to claim 1 , wherein the compound represented by the general formula [1] is a compound represented by the following general formula [1-2]:

wherein R 1 to R 11 are the same as defined in claim 1 .