Azo compound, ink containing azo compound, display including said ink and electronic paper

1. An ink comprising: a solvent having a relative permittivity, measured at a frequency of 1 kHz and a temperature of 22° C., of 3 or less and a solubility in water at 25° C. of 20 mg/L or less; and an azo compound represented by the following general formula (1):

wherein in the general formula (1),

R 1 represents any substituent,

R 2 represents a hydrogen atom or any substituent,

R 3 and R 4 each independently represent an alkyl group which may have a substituent, ring A represents general formula (2),

X represents a nitrogen atom, a methine group, or a methine group having a substituent, and general formula (2) is represented by the following formula:

wherein in the general formula (2),

R 5 represents a hydrogen atom or any substituent

2. The ink according to claim 1 , wherein the solvent comprises at least one member selected from the group consisting of hydrocarbon-based solvents, silicone oils, and fluorocarbon-based solvents.

3. The ink according to claim 1 , wherein a product εC of a molar extinction coefficient ε (Lmol −1 cm −1 ) at an absorption maximum wavelength in an n-decane solution of the azo compound and a saturation concentration C (molL −1 ) at 5° C. of the solution is 1,000 cm −1 or larger.

4. The ink according to claim 1 , which further comprises at least one member selected from the group consisting of heterocyclic compounds, cyanovinyl compounds, and anthraquinone compounds.

5. The ink according to claim 4 , wherein the heterocyclic compounds are at least one compound selected from the group consisting of the following general formulae (4) to (7):

wherein in the general formula (4),

R 101 and R 102 each independently represent a hydrogen atom or any substituent,

D 3 and D 4 each independently represent any substituent, e represents an integer of 0-5, and when e is 2 or larger, the two or more D 3 s present in the molecule may be the same or different, and

g represents an integer of 0-4, and when g is 2 or larger, the two or more D 4 s present in the molecule may be the same or different;

wherein in the general formula (5), R 201 , R 202 , R 203 , R 204 , R 205 , R 206 , R 207 , and R 208 each independently represent a hydrogen atom or any substituent, and

Z represents a nitrogen atom, a methine group or a methine group having a substituent;

wherein in the general formula (6),

R 301 , R 302 , D 5 , and D 6 each independently represent any substituent,

l represents an integer of 0-4, and when 1 is 2 or larger, the two or more D 5 s present in the molecule may be the same or different, and

j represents an integer of 0-4, and when j is 2 or larger, the two or more D 6 s present in the molecule may be the same or different;

wherein in the general formula (7), R 601 , R 602 , D 9 , or D 10 each independently represents any substituent,

A 1 represents a hydrogen atom or any substituent,

p represents an integer of 0-5, and when p is 2 or larger, the two or more D 9 s present in the molecule may be the same or different,

q represents an integer of 0-4, and when q is 2 or larger, the two or more D 10 s present in the molecule may be the same or different,

X 1 represents a nitrogen atom, a methine group, or a methine group having a halogen atom, a cyano group, or a —COOR 605 group as a substituent, and

R 605 represents a hydrogen atom, an alkyl group which has 1-20 carbon atoms and may have a substituent, an aryl group which has 6-20 carbon atoms and may have a substituent, or a heteroaryl group which has 2-20 carbon atoms and may have a substituent.

6. The ink according to claim 4 , wherein the anthraquinone compounds are represented by the following general formula (8):

wherein in the general formula (8),

D 8 represents any substituent, and

t represents an integer of 0-8, and when t is 2 or larger, the two or more D 8 s present in the molecule may be the same or different.

7. The ink according to claim 1 , which is for displays or for optical shutters.

8. A display which comprises a display part including the ink according to claim 1 , wherein an image is displayed by controlling voltage application to the display part.

9. The display according to claim 8 , wherein the display part includes electrophoretic particles or an aqueous medium.

10. The display according to claim 8 , wherein an image is displayed by causing a change in the coloration state by the voltage application.

11. The display according to claim 8 , wherein an image is displayed in an electrowetting mode or an electrophoresis mode.

12. An electronic paper which comprises the display according to claim 8 .

13. An azo compound represented by the following general formula (10):

wherein in the general formula (10),

R 21 represents any substituent,

R 22 and R 23 each independently represent a hydrogen atom or any substituent,

R 24 and R 25 each independently represent an alkyl group which may have a substituent,

X 2 represents a nitrogen atom or a methine group which may have a substituent, and

n′ represents an integer of 0-5.