Phosphonium compounds, as well as salts, hydrates and solvates thereof

Abstract

To provide a negative solvatochromic phosphorescent dye that exhibits a strong emission in a region from red to infrared and, as the polarity of a solvent increases, causes a short wavelength shift of an absorption maximum wavelength and phosphorescence maximum wavelength.SOLUTION: Phosphonium compounds exemplified by products of the following formula or salts, hydrates or solvation thereof.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to phosphonium compounds, as well as salts, hydrates and solvates thereof.

Background Art

[0002] Molecules that exhibit strong luminescence in the red to near-infrared region not only reduce phototoxicity to cells but are also very useful in deep tissue imaging. So far, luminescent dyes in the red to near-infrared region having a phosphaxanthene skeleton are known (see, for example, Patent Document 1).

[0003] On the other hand, from a more general perspective, enhancing the diversity of the absorption and emission characteristics of fluorescent dyes also leads to an expansion of the range of applications.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made to solve the above problems, and an object thereof is to provide a compound that exhibits strong luminescence in the red to near-infrared region.

Means for Solving the Problems

[0006] In view of the above object, as a result of intensive studies, the present inventors have found that a phosphonium compound having a specific phosphaxanthene skeleton exhibits strong luminescence in the red to near-infrared region. Among such phosphonium compounds, the phosphonium fluorescein compound is a negative solvatochromic fluorescent dye in which the absorption maximum wavelength and the fluorescence maximum wavelength shift to shorter wavelengths as the polarity of the solvent increases. The present invention has been completed through further research based on such findings. That is, the present invention includes the following configurations.

[0007] Item 1. General formula (1):

[0008]

Chemical formula

[0009] [In the formula, Y 1 represents an oxygen atom or a substituted or unsubstituted amino cation. Y 2 represents an oxygen anion or a substituted or unsubstituted amino group. R 1 and R 2 are the same or different and represent a substituted or unsubstituted (hetero)aryl group or a substituted or unsubstituted alkyl group. R 3 and R 4 are the same or different and represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group. However, at least one of R 3 and R 4 is a substituted or unsubstituted alkyl group or a substituted or unsubstituted alkoxy group. R 5 represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group. R 6 , R 7 , R 8 and R 9 are the same or different and represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a sulfonic acid group. R 6 and Y 1 , R 7 and Y 2 , R8 and Y 1 , and R 9 and Y 2 At least one selected from the group consisting of may together form a substituted or unsubstituted alkylene group. A phosphonium compound or a salt, hydrate or solvate thereof containing an ion represented by

[0010] Item 2. General formula (1A):

[0011] [Chemical formula]

[0012] [In the formula, R 1 , R 2 , R 3 , R 4 and R 5 are the same as above. R 6a , R 7a , R 8a and R 9a are the same or different and represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a sulfonic acid group. R 10 , R 11 , R 12a and R 13a are the same or different and represent a substituted or unsubstituted alkyl group. R 6a and R 10 , R 7a and R 13a , R 8 and R 11 , and R 9a and R 12a At least one selected from the group consisting of may together form a substituted or unsubstituted alkylene group. The phosphonium compound or a salt, hydrate or solvate thereof according to Item 1, containing a phosphonium rhodamine cation represented by

[0013] Item 3. The phosphonium compound or a salt, hydrate or solvate thereof according to Item 2, having an absorption maximum wavelength at 690 to 730 nm in water.

[0014] Item 4. General formula (1B):

[0015] [Chemical formula]

[0016] [In the formula, R 1 , R 2 , R 3 , R 4 and R 5 are the same as described above. R 6b , R 7b , R 8b and R 9b are the same or different and each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a sulfonic acid group.] The phosphonium compound or a salt, hydrate or solvate thereof according to Item 1, which is a phosphonium fluorescein compound represented by the formula or a salt, hydrate or solvate thereof.

[0017] Item 5. The phosphonium compound or a salt, hydrate or solvate thereof according to Item 4, which has an absorption maximum wavelength at 630 to 660 nm in water.

[0018] Item 6. General formula (1C):

[0019] [Chemical formula]

[0020] [In the formula, R 1 , R 2 , R 3 , R 4 and R 5 are the same as described above. R 6c , R 7c , R 8c and R 9c are the same or different and each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a sulfonic acid group. R 12c and R 13c are the same or different and each represents a substituted or unsubstituted alkyl group. R7c and R 13c , and R 9c and R 12c At least one selected from the group consisting of may together form a substituted or unsubstituted alkylene group. The phosphonium compound or a salt, hydrate or solvate thereof according to claim 1, containing a phosphonium rhodol cation represented by

[0021] Item 7. The phosphonium compound or a salt, hydrate or solvate thereof according to claim 6, having an absorption maximum wavelength at 660 to 690 nm in water.

[0022] Item 8. The R 5 , R 6 , R 7 , R 8 and R 9 are all hydrogen atoms, the phosphonium compound or a salt, hydrate or solvate thereof according to any one of claims 1 to 7.

[0023] Item 9. R 1 and R 2 are the same or different and are a substituted or unsubstituted aryl group, the phosphonium compound or a salt, hydrate or solvate thereof according to any one of claims 1 to 8.

[0024] Item 10. A fluorescent dye containing the phosphonium compound or a salt, hydrate or solvate thereof according to any one of claims 1 to 9.

[0025] Item 11. Containing the phosphonium compound or a salt, hydrate or solvate thereof according to any one of claims 1 to 9, and the phosphonium compound or a salt thereof is represented by the general formula (1B):

[0026]

Chemical formula

[0027] [Wherein, R 1 , R 2 , R 3 , R4 and R 5 is the same as described above. R 6b , R 7b , R 8b and R 9b are the same or different and each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a sulfonic acid group.] A solvatochromic fluorescent dye which is a phosphonium fluorescein compound represented by the formula or a salt, hydrate or solvate thereof.

[0028] The solvatochromic fluorescent dye according to item 11, which is a negative solvatochromic fluorescent dye.

Advantages of the Invention

[0029] According to the present invention, a compound showing strong luminescence in the red to near-infrared region can be provided.

[0030] Among them, the phosphonium rhodamine compound and the phosphonium rhodol compound are cationic compounds, and it is expected that they can selectively visualize mitochondria and the like having a negative charge in cells. In particular, the phosphonium rhodamine compound is a fluorescent dye having a never-before-seen structural feature having a dication, and it is expected that it can particularly selectively visualize mitochondria and the like having a negative charge in cells.

[0031] In addition, the phosphonium fluorescein compound has a cation and an anion in the same molecule, is a fluorescent dye having a never-before-seen structural feature, and has a negative solvatochromism.

Brief Description of the Drawings

[0032]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0033] As used herein, "comprising" is a concept that encompasses any of "comprise", "consist essentially of", and "consist of".

[0034] Also, as used herein, when a numerical range is indicated as "A to B", it means A or more and B or less.

[0035] As used herein, "(hetero)aryl group" means an aryl group or a heteroaryl group.

[0036] 1. Phosphonium compound or its salt, hydrate or solvate The phosphonium compound of the present invention or a salt, hydrate or solvate thereof has the general formula (1):

[0037]

Chemical formula

[0038] [wherein, Y 1 represents an oxygen atom or a substituted or unsubstituted amino cation. Y 2 represents an oxygen anion or a substituted or unsubstituted amino group. R 1 and R 2 are the same or different and each represents a substituted or unsubstituted (hetero)aryl group or a substituted or unsubstituted alkyl group. R 3 and R 4is the same as or different from, and represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group. However, R 3 and R 4 at least one of which is a substituted or unsubstituted alkyl group, or a substituted or unsubstituted alkoxy group. R 5 represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group. R 6 , R 7 , R 8 and R 9 are the same as or different from each other, and represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a sulfonic acid group. R 6 and Y 1 , R 7 and Y 2 , R 8 and Y 1 , and R 9 and Y 2 at least one selected from the group consisting of may together form a substituted or unsubstituted alkylene group.] contains an ion represented by.

[0039] In general formula (1), Y 1 is an oxygen atom or a substituted or unsubstituted amino cation, and Y 2 is an oxygen anion or a substituted or unsubstituted amino group.

[0040] Among these, when Y 1 is a substituted or unsubstituted amino cation and Y 2 is a substituted or unsubstituted amino group, general formula (1A):

[0041] [Chemical formula]

[0042] [In the formula, R 1 , R 2 , R 3 , R 4 and R 5is the same as described above. R 6a , R 7a , R 8a and R 9a are the same or different and each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a sulfonic acid group. R 10 , R 11 , R 12a and R 13a are the same or different and each represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted (hetero)aryl group. R 6a and R 10 , R 7a and R 13a , R 8 and R 11 , and R 9a and R 12a At least one selected from the group consisting of may together form a substituted or unsubstituted alkylene group.] It becomes a phosphonium rhodamine compound containing a phosphonium rhodamine cation represented by or a salt, hydrate or solvate thereof.

[0043] Also, when Y 1 is an oxygen atom and Y 2 is an oxygen anion, the general formula (1B):

[0044] [Chemical formula]

[0045] [In the formula, R 1 , R 2 , R 3 , R 4 and R 5 are the same as described above. R 6b , R 7b , R 8b and R 9b are the same or different and each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a sulfonic acid group.] It becomes a phosphonium fluorescein compound represented by or a salt, hydrate or solvate thereof.

[0046] Also, Y 1 is an oxygen atom and Y 2 is a substituted or unsubstituted amino group, the general formula (1C):

[0047] [ka]

[0048] [In the formula, R 1 , R 2 , R 3 , R 4 and R 5 is the same as above. R 6c , R 7c , R 8c and R 9c are the same or different and represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a sulfonic acid group. 12c and R 13c are the same or different and represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted (hetero)aryl group. 7c and R 13c , and R 9c and R 12c At least one selected from the group consisting of may together form a substituted or unsubstituted alkylene group.] The compound is a phosphonium rhodol compound containing a phosphonium rhodol cation represented by the formula:

[0049] That is, in the general formula (1), Y 1 The substituted or unsubstituted amino cation represented by =(NR 10 R 11 ) + means Y 2 The substituted or unsubstituted amino group represented by the formula: -NR 12a R 13a or -NR 12c R 13c means. R 10 , R 11 , R 12a , N.R. 12c , R 13aand R 13c More details about this will be provided later.

[0050] Thus, the phosphonium compound of the present invention, or a salt, hydrate, or solvate thereof, is Y 1 and Y 2 Depending on the type, it includes three groups of compounds.

[0051] Among these, phosphonium rhodamine compounds or their salts, hydrates, or solvates, and phosphonium rhodol compounds or their salts, hydrates, or solvates, are cationic compounds having a cation on the phosphorus atom of the xanthene skeleton, and are expected to accumulate in negatively charged mitochondria and other areas within cells, enabling selective visualization. In particular, phosphonium rhodamine compounds or their salts, hydrates, or solvates are dicationic compounds having cations at two positions: on the phosphorus atom of the xanthene skeleton and on the nitrogen atom constituting the substituted or unsubstituted amino cation. These fluorescent dyes have structural characteristics never before seen, and are expected to easily accumulate in negatively charged mitochondria and other areas within cells, enabling particularly selective visualization.

[0052] Furthermore, a phosphonium fluorescein compound or a salt, hydrate, or solvate thereof has a cation on the phosphorus atom of the xanthene skeleton and an anion on the oxygen anion, and thus has a cation and an anion in the same molecule, and is therefore a fluorescent dye with unprecedented structural characteristics and exhibits negative solvatochromism.

[0053] In the general formulae (1), (1A), (1B) and (1C), R 1 and R 2 The aryl group represented by the formula (I) can be any of a monocyclic aryl group, a fused ring aryl group, and a polycyclic aryl group, and examples thereof include aryl groups having 6 to 18 carbon atoms (particularly aryl groups having 6 to 14 carbon atoms), such as a phenyl group, a naphthyl group, an anthracenyl group, a phenanthrenyl group, a biphenyl group, a terphenyl group, a fluorenyl group, a pyrenyl group, and a triphenylenyl group.

[0054] R 1 and R 2 The aryl group represented by 2 may have a substituent. Examples of the substituent include, but are not particularly limited to, a hydroxyl group, a halogen atom described below, the above aryl group, a heteroaryl group described below, an alkyl group described below, an alkoxy group described below, an alkenyl group described below, an alkynyl group described below, and the like. When having a substituent, the number of substituents is not particularly limited, and 1 to 5 are preferable, and 1 to 3 are more preferable.

[0055] In General Formulas (1), (1A), (1B), and (1C), R 1 and R 2 As the heteroaryl group represented by 2 , either a monocyclic heteroaryl group or a polycyclic heteroaryl group can be adopted. Examples include a pyrrolidyl group, a pyrrolyl group, a tetrahydrothienyl group, a thienyl group, an oxolanyl group, a furanyl group, an imidazolyl group, a pyrazolyl group, a thiazolyl group, an oxazolyl group, a piperidyl group, a pyridyl group, a pyrazyl group, an indolyl group, an isoindolyl group, a benzimidazolyl group, a quinolyl group, an isoquinolyl group, a quinoxalyl group, and the like.

[0056] R 1 and R 2 The heteroaryl group represented by 2 may have a substituent. Examples of the substituent include, but are not particularly limited to, a hydroxyl group, a halogen atom described below, the above aryl group, the above heteroaryl group, an alkyl group described below, an alkoxy group described below, an alkenyl group described below, an alkynyl group described below, and the like. When having a substituent, the number of substituents is not particularly limited, and 1 to 6 are preferable, and 1 to 3 are more preferable.

[0057] In the above General Formulas (1), (1A), (1B), and (1C), R 1 and R 2 As the alkyl group represented by 2 , either a linear alkyl group or a branched alkyl group can be adopted.

[0058] As the linear alkyl group, a linear alkyl group having 1 to 6 carbon atoms (particularly 1 to 4 carbon atoms) is preferable, and specifically, a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, etc. can be mentioned.

[0059] As the branched alkyl group, a branched alkyl group having 3 to 6 carbon atoms (particularly 3 to 5 carbon atoms) is preferable, and specifically, an isopropyl group, an isobutyl group, a tert-butyl group, a sec-butyl group, a neopentyl group, an isohexyl group, a 3-methylpentyl group, etc. can be mentioned.

[0060] R 1 and R 2 The alkyl group represented by may have a substituent. The substituent that the alkyl group may have is not particularly limited, and examples include a hydroxyl group, a halogen atom described later, the above aryl group, the above heteroaryl group, an alkoxy group described later, an alkenyl group described later, an alkynyl group described later, etc. The number of substituents when having a substituent is not particularly limited, 1 to 6 are preferable, and 1 to 3 are more preferable.

[0061] Among them, as R 1 and R 2 from the viewpoint of molecular stability, etc., a substituted or unsubstituted aryl group, a substituted or unsubstituted monocyclic alkyl group, etc. are preferable, and a substituted or unsubstituted aryl group is more preferable.

[0062] In the above general formulas (1), (1A), (1B) and (1C), as the alkyl group represented by R 3 and R 4 the ones described above can be adopted. The type and number of substituents are the same as well.

[0063] In the above general formulas (1), (1A), (1B) and (1C), as R 3 and R 4The alkoxy group represented by [is not particularly limited, and examples thereof include alkoxy groups having 1 to 6 (particularly 1 to 4) carbon atoms such as methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butyloxy group, isobutyloxy group, sec-butyloxy group, tert-butyloxy group, etc.]

[0064] R 3 and R 4 The alkoxy group represented by [may have a substituent. The substituent that the alkoxy group may have is not particularly limited, and examples thereof include a hydroxyl group, a halogen atom described later, the above aryl group, the above heteroaryl group, the above alkoxy group, an alkenyl group described later, an alkynyl group described later, etc. The number of substituents in the case of having a substituent is not particularly limited, and 1 to 6 are preferable, and 1 to 3 are more preferable.]

[0065] R 3 and R 4 are at least one of a substituted or unsubstituted alkyl group or a substituted or unsubstituted alkoxy group. When both of R 3 and R 4 are hydrogen atoms, the stability of the compound is poor. Also, from the viewpoint of the stability of the compound, it is preferable that both R 3 and R 4 are a substituted or unsubstituted alkyl group or a substituted or unsubstituted alkoxy group.]

[0066] In the above general formulas (1), (1A), (1B) and (1C), as the alkyl group and aryl group represented by R 5 , those described above can be adopted. The types and numbers of substituents are the same.]

[0067] In general formulas (1), (1A), (1B) and (1C), examples of the halogen atom represented by R 5 include a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.]

[0068] In general formulas (1), (1A), (1B) and (1C), R 5Examples of the alkenyl group represented by include alkenyl groups having 2 to 6 (particularly 2 to 4) carbon atoms such as vinyl group, allyl group, 1-butenyl group, 2-butenyl group and the like.

[0069] R 5 The alkenyl group represented by may have a substituent. The substituent that the alkenyl group may have is not particularly limited, and examples thereof include a hydroxyl group, the above halogen atom, the above aryl group, the above heteroaryl group, the above alkoxy group, the above alkenyl group, the alkynyl group described later and the like. The number of substituents in the case of having a substituent is not particularly limited, and 1 to 6 are preferable, and 1 to 3 are more preferable.

[0070] In General Formulas (1), (1A), (1B) and (1C), R 5 Examples of the alkynyl group represented by include alkynyl groups having 2 to 6 (particularly 2 to 4) carbon atoms such as ethynyl group, 1-propynyl group, propargyl group, 1-butynyl group, 2-butynyl group and the like.

[0071] R 5 The alkynyl group represented by may have a substituent. The substituent that the alkynyl group may have is not particularly limited, and examples thereof include a hydroxyl group, the above halogen atom, the above aryl group, the above heteroaryl group, the above alkoxy group, the above alkenyl group, the above alkynyl group and the like. The number of substituents in the case of having a substituent is not particularly limited, and 1 to 6 are preferable, and 1 to 3 are more preferable.

[0072] R 5 From the viewpoint of ease of synthesis and the like, it is preferably a hydrogen atom.

[0073] In General Formula (1), R 6 , R 7 , R 8 and R 9 The halogen atom and alkyl group represented by can adopt those described above. The type and number of substituents are the same. Also, R in General Formula (1A) 6a , R 7a , R 8a and R9a The halogen atom and alkyl group represented by 9a , and R in the general formula (1B) 6b , R 7b , R 8b and R 9b The halogen atom and alkyl group represented by 9b , and R in the general formula (1C) 6c , R 7c , R 8c and R 9c The same applies to the halogen atom and alkyl group represented by 9c .

[0074] In the general formula (1), R 6 , R 7 , R 8 and R 9 are preferably hydrogen atoms from the viewpoints of ease of synthesis, absorption maximum wavelength, fluorescence maximum wavelength, solvatochromism, etc. When the purpose is to improve the photo stability, R 6 , R 7 , R 8 and R 9 can also be halogen atoms. Also, R 6a , R 7a , R 8a and R 9a in the general formula (1A), R 6b , R 7b , R 8b and R 9b in the general formula (1B), and R 6c , R 7c , R 8c and R 9c in the general formula (1C) are the same.

[0075] In the general formula (1), the substituted or unsubstituted aminocation represented by Y 1 means =(NR 10 R 11 ) + as described in the general formula (1A).

[0076] R 10 and R 11 The alkyl groups represented by 10 and 11 can adopt those described above. The types and numbers of substituents are the same.

[0077] R 10 and R 11 When it is a (hetero)aryl group, it causes a decrease in fluorescence intensity. When it is a hydrogen atom, it dissociates when it becomes a quinoid form and loses its cationicity. On the other hand, when it is an alkyl group, it does not impair the fluorescence intensity.

[0078] In general formula (1), for Y 1 when aiming for a phosphonium rhodamine compound or its salt, hydrate or solvate, a substituted or unsubstituted aminocation is preferably employed. When aiming for a phosphonium fluorescein compound or its salt, hydrate or solvate, or a phosphonium rhodol compound or its salt, hydrate or solvate, an oxygen atom is preferably employed.

[0079] In general formula (1), the substituted or unsubstituted amino group represented by Y 2 is, as described in general formulas (1A) and (1C), -NR 12a R 13a or -NR 12c R 13c which means.

[0080] R 12a 、R 12c 、R 13a and R 13c The alkyl groups represented by can employ those described above. The types and numbers of substituents are the same.

[0081] R 12a 、R 12c 、R 13a and R 13c When it is a (hetero)aryl group, it causes a decrease in fluorescence intensity. When it is a hydrogen atom, it dissociates when it becomes a quinoid form and loses its cationicity. On the other hand, when it is an alkyl group, it does not impair the fluorescence intensity.

[0082] In general formula (1), for Y 2Regarding, when targeting a phosphonium rhodamine compound or a salt, hydrate or solvate thereof, or a phosphonium rhodol compound or a salt, hydrate or solvate thereof, a substituted or unsubstituted amino group is employed, and when targeting a phosphonium fluorescein compound or a salt, hydrate or solvate thereof, an oxygen anion is preferably employed.

[0083] In the above general formula (1), R 6 and Y 1 、R 7 and Y 2 、R 8 and Y 1 、and R 9 and Y 2 may together form a substituted or unsubstituted alkylene group. Further, in the above general formula (1A), R 6a and R 10 、R 7a and R 13a 、R 8 and R 11 、and R 9 and R 12a may together form a substituted or unsubstituted alkylene group. Further, in the above general formula (1C), R 7c and R 13c 、and R 9c and R 12c may together form a substituted or unsubstituted alkylene group.

[0084] Examples of such an alkylene group include alkylene groups having 1 to 6 carbon atoms (particularly 2 to 4 carbon atoms), such as a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, etc. The alkylene group may have a substituent. Examples of the substituent include, without particular limitation, a hydroxyl group, the above halogen atom, the above aryl group, the above heteroaryl group, etc. The number of substituents when having a substituent is not particularly limited, and 1 to 6 are preferred, and 1 to 3 are more preferred.

[0085] However, from the viewpoint of further improving water solubility and further suppressing non-specific adsorption during imaging, R 6 and Y1 , R 7 and Y 2 , R 8 and Y 1 , and R 9 and Y 2 None of them is preferably bonded to each other to form a substituted or unsubstituted alkylene group.

[0086] Examples of the phosphonium compound of the present invention that satisfies such conditions include, for example,

[0087] [In the formula, Ph represents a phenyl group.]

[0088] [In the formula, Ph represents a phenyl group.] A phosphonium compound represented by the like or a salt, hydrate or solvate thereof is preferable.

[0089] The phosphonium compound of the present invention can also exist in a salt state. In the case of the phosphonium fluorescein compound represented by the general formula (1B), since it has a cation and an anion in the molecule, it can become an inner salt (zwitterion). On the other hand, in the case of the phosphonium rhodamine compound represented by the general formula (1A) and the phosphonium rhodol compound represented by the general formula (1C), as acid addition salts, for example, mineral salts such as hydrochloride, sulfate, nitrate, etc.; organic acid salts such as p-toluenesulfonate, methanesulfonate, maleate, oxalate, etc. can be mentioned. In addition to these, salts with amino acids such as glycine may also be formed.

[0090] Further, the phosphonium compound of the present invention may exist as a hydrate or a solvate, and all of these substances are included in the scope of the present invention.

[0091] Such a phosphonium compound of the present invention or a salt, hydrate or solvate thereof, for example, in the case of a phosphonium rhodamine compound represented by the general formula (1A) or a salt, hydrate or solvate thereof, in water, the absorption maximum wavelength is 690 to 730 nm, particularly preferably 695 to 725 nm, and the fluorescence maximum wavelength is 730 to 770 nm, particularly preferably 735 to 765 nm. Further, in the case of a phosphonium fluorescein compound represented by the general formula (1B) or a salt, hydrate or solvate thereof, in water, the absorption maximum wavelength is 630 to 660 nm, particularly preferably 635 to 655 nm, and the fluorescence maximum wavelength is 670 to 700 nm, particularly preferably 675 to 695 nm. Further, in the case of a phosphonium rhodol compound represented by the general formula (1C) or a salt, hydrate or solvate thereof, in water, the absorption maximum wavelength is 660 to 690 nm, particularly preferably 665 to 685 nm, and the fluorescence maximum wavelength is 700 to 730 nm, particularly preferably 695 to 725 nm.

[0092] When the phosphonium compound of the present invention or a salt, hydrate or solvate thereof (the fluorescent dye of the present invention) is a phosphonium fluorescein compound or a salt, hydrate or solvate thereof, it is a group of compounds (solvatochromic fluorescent dyes) in which the absorption maximum wavelength and the fluorescence maximum wavelength change depending on the polarity of the solvent. For example, in a nonpolar solvent such as toluene with a very low solvent polarity, the absorption maximum wavelength is 670 to 700 nm, particularly preferably 675 to 695 nm, and the fluorescence maximum wavelength is 720 to 750 nm, particularly preferably 725 to 745 nm.

[0093] Solvatochromic fluorescent dyes are expected as fluorescent dyes for expanding the application range. Since solvatochromic fluorescent dyes can distinguish the polarity of the surrounding environment, they are widely used as fluorescent probes. However, conventionally used solvatochromic fluorescent dyes are fluorescent dyes in which the absorption maximum wavelength and the fluorescence maximum wavelength change depending on the magnitude of the solvent polarity, but there is a problem that the fluorescence quantum yield is extremely small in a highly polar solvent such as water.

[0094] Solvatochromic fluorescent dyes can be divided into fluorescent dyes with a positive solvent effect and those with a negative solvent effect. Most solvatochromic fluorescent dyes have a positive solvent effect. As shown in the left figure of Fig. 1, as the polarity of the solvent increases, the absorption maximum wavelength and the fluorescence maximum wavelength shift to longer wavelengths. Conversely, solvatochromic fluorescent dyes with a negative solvent effect typically show a short-wavelength shift in the absorption maximum wavelength and the fluorescence maximum wavelength as the polarity of the solvent increases, as shown in the right figure of Fig. 1. For cell imaging, since a large fluorescence quantum yield is required in a highly polar solvent such as water, negative solvatochromic fluorescent dyes with a negative solvent effect, such as those of the present invention, are useful.

[0095] From the above, it is possible to make the absorption maximum wavelength and the fluorescence maximum wavelength longer and to enhance the solvent dependence of the absorption maximum wavelength and the fluorescence maximum wavelength. When the compound is a phosphonium fluorescein compound or a salt, hydrate or solvate thereof, when the solvent is an aqueous solution such as water or a PBS buffer solution, the absorption maximum wavelength and the fluorescence maximum wavelength can be made particularly large. That is, among the fluorescent dyes of the present invention, when the compound is a phosphonium fluorescein compound or a salt, hydrate or solvate thereof, it can also be referred to as a negative solvatochromic fluorescent dye in which the absorption maximum wavelength and the fluorescence maximum wavelength become shorter as the polarity of the solvent increases.

[0096] Thus, the phosphonium compound or a salt, hydrate or solvate thereof of the present invention is useful not only as a reagent for academic research such as various stains and fluorescent dyes, but also as a detection reagent for diagnostic devices such as fluorescent dyes having specific excitation and fluorescence wavelengths that conform to the device specifications.

[0097] 2. Method for producing phosphonium compound or its salt, hydrate or solvate The phosphonium compound or a salt, hydrate or solvate thereof of the present invention is not particularly limited. For example, taking the phosphonium fluorescein compound represented by the general formula (B) as an example, the following reaction formula 1:

[0098] [Chemical formula]

[0099] [In the formula, R 1 , R 2 , R 3 , R 4 , R 5 , R 6b , R 7b , R 8b , R 9b is the same as described above. R 14 and R 15 are the same or different and represent a substituted or unsubstituted alkyl group, a substituted or unsubstituted acyl group, or a substituted or unsubstituted alkoxycarbonyl group. X - represents a counter ion.] can be synthesized accordingly.

[0100] In Reaction Scheme 1, as the alkyl group represented by R 14 and R 15 , those described above can be adopted. The types and numbers of substituents are the same.

[0101] In Reaction Scheme 1, as the acyl group represented by R 14 and R 15 , for example, alkanoyl groups having 1 to 6 carbon atoms such as formyl group, acetyl group, propionyl group, etc. can be mentioned.

[0102] R 14 and R 15 The acyl group represented by may have a substituent. The substituents that the acyl group may have are not particularly limited, and examples include a hydroxyl group, the above halogen atom, the above aryl group, the above heteroaryl group, the above alkoxy group, the above alkenyl group, the above alkynyl group, etc. When having a substituent, the number of substituents is not particularly limited, and 1 to 6 are preferable, and 1 to 3 are more preferable.

[0103] In Reaction Scheme 1, R 14 and R 15Examples of the alkoxycarbonyl group represented by [ ] include alkoxycarbonyl groups having 1 to 6 carbon atoms such as methoxycarbonyl group, ethoxycarbonyl group, n-propoxycarbonyl group, isopropoxycarbonyl group, etc.

[0104] R 14 and R 15 The alkoxycarbonyl group represented by [ ] may have a substituent. The substituent that the alkoxycarbonyl group may have is not particularly limited, and examples thereof include a hydroxyl group, the above halogen atom, the above aryl group, the above heteroaryl group, the above alkoxy group, the above alkenyl group, the above alkynyl group, etc. The number of substituents when having a substituent is not particularly limited, 1 to 6 are preferable, and 1 to 3 are more preferable.

[0105] In Reaction Scheme 1, as the counter ion represented by X - , chloride ion (Cl - ), bromide ion (Br - ), iodide ion (I - ), nitrate ion (NO3 - ), trifluoromethylacetate ion (CF3COO - ), methanesulfonate ion, toluenesulfonate ion, trifluoromethanesulfonate ion, tetrafluoroborate ion, hexafluorophosphate ion, etc. may be mentioned.

[0106] As the compound represented by the general formula (2) used as a raw material, a known or commercially available product can be used. When synthesizing the compound represented by the general formula (2), for example, it can be synthesized according to the method described in Philos Trans A Math Phys Eng Sci. 2017 Aug 28; 375 (2101): 20170007.

[0107] In addition, the phosphonium rhodol compound and the phosphonium rhodamine compound can also be synthesized in the same manner by selecting an appropriate substrate instead of the compound (2) represented by the general formula (2) which is a substrate.

[0108] Compound (2) → Compound (3) There are no particular restrictions on the lithium compound, and known ones can be adopted. For example, alkyllithiums such as ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, n-pentyllithium, n-hexyllithium, etc.; cycloalkyllithiums such as cyclohexyllithium; aryllithiums such as phenyllithium, etc. Among these, in this step, from the viewpoints of yield and ease of synthesis, alkyllithium is preferable, and n-butyllithium is more preferable. These lithium compounds can be used alone or in combination of two or more.

[0109] The amount of the above lithium compound used is not particularly limited, and from the viewpoints of yield, ease of synthesis, etc., 0.8 to 5.0 moles, preferably 1.0 to 3.0 moles, is preferable per 1 mole of compound (2).

[0110] There are no particular restrictions on the zinc compound, and from the viewpoints of yield, ease of synthesis, etc., zinc halides such as zinc chloride and zinc bromide are preferable.

[0111] The amount of the above zinc compound used is not particularly limited, and from the viewpoints of yield, ease of synthesis, etc., 0.1 to 5 moles, preferably 0.5 to 2 moles, is preferable per 1 mole of compound (2).

[0112] The zinc compound can also form a complex using a ligand. In this case, the ligand compound can be added to form a complex in the system, or the complex can be added to the system after formation.

[0113] Examples of such ligands include 2,2'-bipyridyl, 4,4'-(tert-butyl)bipyridyl, 4,4'-bis(trifluoromethyl)-2,2'-bipyridyl, 5,5'-bis(trifluoromethyl)-2,2'-bipyridyl, 6,6'-bis(trifluoromethyl)-2,2'-bipyridyl, 4,4'-bis(methoxycarbonyl)-2,2'-bipyridyl, 4,4'-dimethyl-2,2'-bipyridyl, 5,5'-dimethyl-2,2'-bipyridyl, 4,4'-dimethoxy-2,2'-bipyridyl, 4,4'-dicyano-2,2'-bipyridyl, phenanthroline, 2,2'-bipyrimidyl, 1,4-diazabicyclo[2.2.2]octane, tetramethylethylenediamine (TMEDA), 1,1'-bis(diphenylphosphino)ferrocene, diphenylphosphinomethane, 1,2-bis(diphenylphosphino)ethane, 1,3-bis(diphenylphosphino)propane, 1,5-bis(diphenylphosphino)pentane, 1,2-bis(dicyclohexylphosphino)ethane, 1,3-(dicyclohexylphosphino)propane, 1,2-bis(di-tert-butylphosphino)ethane, 1,3-bis(di-tert-butylphosphino)propane, 1,2-bis(diphenylphosphino)benzene, and the like. These ligands can be used alone or in combination of two or more.

[0114] The amount of the above ligand used is not particularly limited, and from the viewpoints of yield, ease of synthesis, etc., 0.1 to 5 moles, more preferably 0.5 to 2 moles, per mole of the zinc compound is preferred.

[0115] The organic solvent that can be used in this step is not particularly limited, and for example, cyclic ether compounds such as tetrahydrofuran and dioxane are preferred.

[0116] The reaction conditions are preferably such that the reaction proceeds sufficiently. For example, the reaction atmosphere is preferably an oxidizing atmosphere (such as an oxygen gas atmosphere, air, etc.), the reaction temperature is preferably room temperature (about 20 to 30 °C), and the reaction time is 5 minutes to 96 hours, particularly preferably 10 minutes to 72 hours.

[0117] After the reaction is completed, purification treatment can be carried out according to a conventional method as necessary, and the following steps can be performed.

[0118] Compound (3) → Compound (1B) Examples of the Lewis acid include boron tribromide, aluminum tribromide, boron trichloride, aluminum trichloride, iodotrimethylsilane, and the like. These Lewis acids can be used alone or in combination of two or more.

[0119] Usually, it is preferable to use an excessive amount of the Lewis acid with respect to the compound (3). The amount of the Lewis acid used is preferably 2 to 10 moles, more preferably 3 to 8 moles, per 1 mole of the compound (3).

[0120] The reaction can usually be carried out in the presence of a reaction solvent. Examples of the reaction solvent that can be used include aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic halogenated hydrocarbons such as dichloromethane, dichloroethane, chloroform, and carbon tetrachloride; hydrocarbons such as pentane, hexane, heptane, and cyclohexane. From the viewpoints of ease of synthesis, yield, etc., aliphatic halogenated hydrocarbons are preferable, and dichloromethane is more preferable. These reaction solvents can be used alone or in combination of two or more.

[0121] The reaction atmosphere can usually adopt an inert gas atmosphere (such as an argon gas atmosphere or a nitrogen gas atmosphere). The reaction temperature can be carried out under heating, at room temperature, or under cooling, and usually, -50 to 100 °C is preferable, and 0 to 50 °C is more preferable. The reaction time is not particularly limited, and it is preferably set to a time when the reaction proceeds sufficiently.

[0122] After the reaction is completed, by performing purification treatment according to a conventional method as necessary, the phosphonium fluorescein compound of the present invention or its salt, hydrate, or solvate can be obtained.

Examples

[0123] Based on the embodiments, the present invention will be specifically described, but the present invention is not limited only to these.

[0124] Synthesis Example 1: 4-Bromo-3-(diphenylphosphino)anisole

[0125]

Chemical formula

[0126] In the formula, Me represents a methyl group. iPr represents an isopropyl group. Ph represents a phenyl group. THF represents tetrahydrofuran.

[0127] To a solution of 4-bromo-3-iodoanisole in anhydrous tetrahydrofuran (THF), isopropylmagnesium bromide was added dropwise at -20 °C. After stirring at -20 °C for 1 hour, diphenylphosphine chloride was added, and the resulting mixture was stirred at -20 °C for 1 hour. The mixture was warmed to room temperature and stirred overnight. The reaction was stopped by adding a saturated aqueous solution of ammonium chloride, and the aqueous phase was extracted 3 times with ethyl acetate (EtOAc). The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was subjected to silica gel column chromatography (eluent: hexane / ethyl acetate (EtOAc) = 10:1 to 5:1), followed by recrystallization from a hexane / dichloromethane solvent system at room temperature to give 4-bromo-3-(diphenylphosphino)anisole (4.40 g, 11.9 mmol, 59%) as a white solid.

[0128] Synthesis Example 2

[0129]

Chemical formula

[0130] In the formula, Me represents a methyl group. Ph represents a phenyl group. n Bu represents an n-butyl group. THF represents tetrahydrofuran.

[0131] To a solution of 4-bromo-3-(diphenylphosphino)anisole (3.71 g, 10 mmol) obtained in Synthesis Example 1 in anhydrous tetrahydrofuran (THF; 25 mL), a 1.58 M hexane solution of n-butyllithium ( n BuLi; 7 mL, 11 mmol) was slowly added at -78 °C, and the resulting mixture was stirred at the same temperature for 1 hour. A solution of Weinreb amide of 4-methoxybenzoic acid (1.95 g, 10 mmol) in tetrahydrofuran (THF; 8 mL) was slowly added. The reaction mixture was warmed to room temperature and stirred overnight. The reaction was stopped by adding a saturated aqueous solution of ammonium chloride, and the aqueous phase was extracted 3 times with ethyl acetate (EtOAc). The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was purified by silica gel column chromatography (eluent: hexane / ethyl acetate (EtOAc) = 5:1 to 3:1) to obtain a diaryl ketone compound (2.27 g, 5.3 mmol, 53%) as a yellowish solid.

[0132] Synthesis Example 3

[0133]

Chemical formula

[0134] In the formula, Me represents a methyl group. Ph represents a phenyl group. THF represents tetrahydrofuran.

[0135] A solution of the diaryl ketone compound (2.13 g, 5 mmol) of Synthesis Example 2 dissolved in 25 mL of anhydrous tetrahydrofuran (THF) was added to a 2,6-xylilylmagnesium bromide / lithium chloride solution (1 M, 10 mL). The cooling bath was removed, and the reaction mixture was stirred at room temperature for 2 hours and at 70 °C for 2 days. The reaction was stopped by adding a saturated aqueous solution of ammonium chloride, and the aqueous phase was extracted 3 times with ethyl acetate (EtOAc). The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was purified by silica gel column chromatography (eluent: hexane / ethyl acetate (EtOAc) = 10:1 to 5:1) to obtain the triaryl alcohol compound (1.08 g, 2 mmol, 38%) as a white solid.

[0136] Synthesis Example 4

[0137] [Chemical formula]

[0138] In the formula, Me represents a methyl group. Ph represents a phenyl group. Ac represents an acetyl group. TFA represents trifluoroacetic acid. X - represents a counter ion.

[0139] Trifluoroacetic acid (TFA; 0.5 mL, 6 mmol) was slowly added to a solution of the triaryl alcohol compound (1.08 g, 2 mmol) obtained in Synthesis Example 3 in acetic anhydride (8 mL) at room temperature, and the resulting mixture was stirred at the same temperature for 1 hour. Next, water was added, and the aqueous phase was extracted 3 times with dichloromethane. The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was purified by silica gel column chromatography (eluent: chloroform / methanol (MeOH) = 5:1) to obtain the corresponding phosphonium salt (1.26 g, 2 mmol, 99%) as a white solid.

[0140] Synthesis Example 5

[0141] [Chemistry]

[0142] In the formula, Me represents a methyl group. Ph represents a phenyl group. n BuLi represents n-butyllithium. TMEDA represents tetramethylethylenediamine. X - represents a counter ion.

[0143] To a solution of the phosphonium salt (0.83 g, 2.1 mmol) obtained in Synthesis Example 4 in anhydrous tetrahydrofuran (THF; 10 mL), 1.58 M n-butyllithium ( n BuLi; 1.58 mL, 2.5 mmol) and a zinc chloride / tetramethylethylenediamine (TMEDA) complex (0.53 g, 2.1 mmol) were slowly added at -78 °C, and the resulting mixture was stirred under an argon atmosphere for 1 hour. After replacing argon with oxygen, stirring was maintained. The reaction was stopped by adding a saturated aqueous solution of ammonium chloride, and the aqueous phase was extracted three times with dichloromethane. The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was purified by silica gel column chromatography (using chloroform / methanol (MeOH) = 10:1 to 5:1 as the eluent) to obtain the phosphonium alcohol compound (0.81 g, 1.3 mmol, 60%) as a white solid.

[0144] Example 1: Phosphonium fluorescein

[0145] [Chemistry]

[0146] In the formula, Me represents a methyl group. Ph represents a phenyl group.

[0147] To a solution of the phosphonium alcohol compound (0.1 g, 0.15 mmol) obtained in Example 1 in anhydrous dichloromethane (CH2Cl2; 2 mL), a 1.0 M dichloromethane solution of boron tribromide (BBr3; 0.8 mL, 0.8 mmol) was slowly added at -78 °C, and the resulting mixture was stirred at the same temperature for 30 minutes. The mixture was warmed to room temperature and stirred for 24 hours. The reaction was stopped by adding water, and the aqueous phase was extracted 4 times with dichloromethane. The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was purified by silica gel column chromatography (using chloroform / methanol (MeOH) = 10:1 as the eluent) to obtain the phosphonium fluorescein compound (0.03 g, 0.06 mmol, 41%) as a red solid. 1 H NMR (400 MHz, CDCl3) δ 7.88 - 7.80 (2H, m), 7.74 - 7.66 (8H, m), 7.29 (1H, t, J = 7.6 Hz), 7.14 (2H, d, J = 7.6 Hz), 6.86 (2H, dd, J = 10.0, 8.0 Hz), 6.79 (2H, dd, J = 19.2, 2.4 Hz), 6.49 (2H, dd, J = 10.0, 2.4 Hz), 1.93 (6H, s).

[0148] Example 2: Phosphonium fluorescein

[0149]

Chemical formula

[0150] In the formula, Ph represents a phenyl group.

[0151] The 2,6 - xylylmagnesium bromide / lithium chloride solution used in Synthesis Example 3 was changed to a 2 - tolylmagnesium bromide / lithium chloride solution, and synthesized according to the procedures of Synthesis Examples 3 - 5 and Example 1. 11H NMR (400 MHz, CDCl3) δ 7.88 - 7.79 (2H, m), 7.75 - 7.62 (8H, m), 7.39 (1H, t, J = 7.0 Hz), 7.31 (1H, t, J = 7.0 Hz), 7.30 (1H, d, J = 7.0 Hz), 7.07 (1H, d, J = 7.0 Hz), 6.87 (2H, dd, J = 9.8, 8.0 Hz), 6.80 (2H, dd, J = 18.4, 2.4 Hz), 6.47 (2H, dd, J = 9.8, 2.4 Hz), 1.95 (3H, s).

[0152] Synthesis Example 6

[0153]

Chem.

[0154] In the formula, Me represents a methyl group. Ph represents a phenyl group.

[0155] To a solution of 4-bromo-3-(diphenylphosphino)anisole (1.23 g, 3.3 mmol) obtained in Synthesis Example 1 in anhydrous tetrahydrofuran (THF; 11 mL), a 1.58 M hexane solution of n-butyllithium ( n BuLi; 7 mL, 3.6 mmol) was slowly added at -78 °C, and the resulting mixture was stirred at the same temperature for one hour. A solution of Weinreb amide of 4-dimethylaminobenzoic acid (0.63 g, 3 mmol) in tetrahydrofuran (THF; 3 mL) was slowly added. The mixture was warmed to room temperature overnight. The reaction was stopped by adding a saturated aqueous solution of ammonium chloride, and the aqueous phase was extracted three times with ethyl acetate. The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. Purification by silica gel chromatography (using hexane / ethyl acetate = 5:1 to 1:1 as the eluent) gave the corresponding diaryl ketone compound (0.51 g, 1.16 mmol, 39%) as a yellowish solid.

[0156] Synthesis Example 7

[0157]

Chem.

[0158] In the formula, Me represents a methyl group. Ph represents a phenyl group.

[0159] To a solution of 2-tolylmagnesium bromide / lithium chloride (0.3 M, 12 mL) in 24 mL of anhydrous tetrahydrofuran (THF), a solution of the diarylketone compound (0.51 g, 1.16 mmol) obtained in Synthesis Example 6 dissolved in 24 mL of anhydrous tetrahydrofuran (THF) was added at 0 °C. The reaction mixture was stirred at room temperature for 2 hours and at 70 °C overnight. The reaction was stopped by adding a saturated aqueous solution of ammonium chloride, and the aqueous phase was extracted three times with ethyl acetate. The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. Purification by silica gel chromatography (using hexane / ethyl acetate = 5:1 to 1:1 as the eluent) gave the corresponding triarylmethanol compound (0.11 g, 0.21 mmol, 18%) as a white solid.

[0160] Synthesis Example 8

[0161]

Chem.

[0162] In the formula, Me represents a methyl group. Ph represents a phenyl group. Ac represents an acetyl group. TFA represents trifluoroacetic acid.

[0163] To a solution of the triarylmethanol compound (0.11 g, 0.21 mmol) obtained in Synthesis Example 7 in acetic anhydride (Ac2O; 1 mL), trifluoroacetic acid (TFA; 0.1 mL, 1 mmol) was slowly added at room temperature, and the resulting mixture was stirred at the same temperature for 2 hours. Next, water was added, and the aqueous phase was extracted 3 times with dichloromethane. The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. It was purified by silica gel chromatography (using chloroform / methanol = 10:1 to 5:1 as the eluent) to obtain the corresponding phosphonium salt (0.1 g, 0.2 mmol, 95%) as a white solid.

[0164] Synthesis Example 9

[0165] [Chemical Formula]

[0166] In the formula, Me represents a methyl group. Ph represents a phenyl group. n BuLi represents n-butyllithium. TMEDA represents tetramethylethylenediamine. THF represents tetrahydrofuran.

[0167] To a solution of the phosphonium salt (0.10 g, 0.20 mmol) obtained in Synthesis Example 8 in anhydrous tetrahydrofuran (THF; 2 mL), 1.58 M n-butyllithium at -78 °C ( nn-BuLi (1.58 mL, 0.24 mmol) and zinc chloride / tetramethylethylenediamine (TMEDA) complex (0.05 g, 0.2 mmol) were slowly added, and the resulting mixture was stirred for 1 hour under an argon atmosphere. After replacing argon with oxygen, stirring was maintained. The reaction was stopped by adding a saturated aqueous solution of ammonium chloride, and the aqueous phase was extracted three times with dichloromethane. The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was purified by silica gel column chromatography (using chloroform / methanol (MeOH) = 10:1 to 5:1 as the eluent) to obtain the corresponding phosphonium alcohol compound (0.07 g, 0.13 mmol, 65%).

[0168] Example 3: Phosphonium rhodol

[0169] [Chemical formula]

[0170] In the formula, Me represents a methyl group. Ph represents a phenyl group.

[0171] To a solution of the phosphonium alcohol (0.07 g, 0.13 mmol) obtained in Synthesis Example 9 in anhydrous dichloromethane (CH2Cl2; 1.3 mL), a 1.0 M dichloromethane solution of boron tribromide (BBr3; 0.67 mL, 0.67 mmol) was slowly added at -78 °C, and the resulting mixture was stirred at the same temperature for 30 minutes. The mixture was warmed to room temperature and stirred for 24 hours. The reaction was stopped by adding water, and the aqueous phase was extracted four times with dichloromethane. The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. The residue was purified by silica gel column chromatography (using chloroform / methanol (MeOH) = 10:1 as the eluent) to obtain the corresponding phosphonium rodoil (0.06 g, 0.1 mmol, 75%) as a blue solid. 11H NMR (400 MHz, CD3OD) δ 7.99 - 7.67 (10H, m), 7.46 - 7.37 (3H, m), 7.22 (1H, d, J = 7.6 Hz), 7.19 - 6.93 (7H, m), 6.77 (1H, dd, J = 16.0, 2.4 Hz), 2.90 (6H, s), 1.60 (3H, s).

[0172] Synthesis Example 10

[0173]

Chem.

[0174] In the formula, Boc represents a tert-butyloxycarbonyl group. Me represents a methyl group. Ph represents a phenyl group.

[0175] To a solution of N-Boc-N-methyl-4-bromo-3-(diphenylphosphino)aniline (1.03 g, 2.2 mmol) in anhydrous tetrahydrofuran (THF; 7 mL) was slowly added a 1.56 M hexane solution of n-butyllithium ( n BuLi; 1.41 mL, 2.2 mmol) at -78 °C, and the resulting mixture was stirred at the same temperature for one hour. A solution of Weinreb amide of N-Boc-N-methylaminobenzoic acid (0.64 g, 2.2 mmol) in tetrahydrofuran (THF; 3 mL) was slowly added. The mixture was warmed to room temperature overnight. The reaction was stopped by adding saturated aqueous ammonium chloride, and the aqueous phase was extracted three times with ethyl acetate. The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. Purification by silica gel chromatography (using hexane / ethyl acetate = 3:1 to 1:1 as the eluent) gave the corresponding diaryl ketone compound (0.78 g, 1.25 mmol, 57%) as a yellow solid.

[0176] Synthesis Example 11

[0177]

Chem.

[0178] In the formula, Boc represents a tert-butyloxycarbonyl group. Ph represents a phenyl group.

[0179] A solution of the diaryl ketone compound (0.78 g, 1.25 mmol) obtained in Synthesis Example 10 dissolved in 24 mL of anhydrous tetrahydrofuran (THF) was added to a 2,6-xylilylmagnesium bromide / lithium chloride solution (0.2 M, 12 mL) at 0 °C. The reaction mixture was stirred at room temperature for 2 hours and at 70 °C overnight. The reaction was stopped by adding a saturated aqueous solution of ammonium chloride, and the aqueous phase was extracted three times with ethyl acetate. The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. Purification by silica gel chromatography (hexane / ethyl acetate = 5:1 to 1:1 as the eluent) gave the corresponding triarylmethanol compound (0.41 g, 0.55 mmol, 44%) as a white solid.

[0180] Synthesis Example 12

[0181] [Chemical formula]

[0182] In the formula, Boc represents a tert-butyloxycarbonyl group. Ph represents a phenyl group. TFA represents trifluoroacetic acid.

[0183] To a solution of the triarylmethanol compound (0.4 g, 0.55 mmol) of Synthesis Example 10 in anhydrous dichloromethane (2 mL), trifluoroacetic acid (TFA; 0.21 mL, 2.8 mmol) was slowly added at room temperature, and the resulting mixture was stirred at the same temperature for 3 days. Next, water was added, and the aqueous phase was extracted 3 times with dichloromethane. The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. It was purified by silica gel chromatography (using chloroform / methanol = 10:1 to 5:1 as the eluent) to obtain the corresponding phosphonium salt (0.31 g, 0.5 mmol, 90%) as a green solid.

[0184] Example 4: Phosphonium rhodamine

[0185]

Chemical formula

[0186] In the formula, Ph represents a phenyl group. Me represents a methyl group. DMF represents dimethylformamide.

[0187] To a solution of the phosphonium salt (0.07 g, 0.11 mmol) obtained in Synthesis Example 12 in anhydrous dimethylformamide (DMF; 0.5 mL), potassium carbonate (0.05 g, 0.33 mmol) and iodomethane (15 μL, 0.24 mmol) were slowly added at room temperature, and the resulting mixture was stirred at 80 °C for 3 days. The same amount of iodomethane was additionally added every other day. Next, water was added, and the aqueous phase was washed 5 times with ethyl acetate. Then, a 2 M aqueous solution of sodium tetrafluoroborate was added, and it was extracted 3 times with dichloromethane. The combined organic phases were washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated. It was recrystallized from dichloromethane / diethyl ether to obtain the corresponding phosphonium rhodamine compound (10 mg, 0.01 mmol, 12%) as a green solid. 11H NMR (400 MHz, CD3OD) δ 8.05 - 7.95 (6H, m), 7.89 - 7.82 (4H, m), 7.45 - 7.36 (3H, m), 7.29 - 7.22 (4H, m), 7.14 (2H, dd, J = 9.8, 2.6 Hz), 3.37 (12H, s), 1.90 (6H, s).

[0188] Test Example 1: Photophysical properties The absorption spectra and fluorescence spectra of the phosphonium fluorescein compound (Example 1), the phosphonium rhodol compound (Example 3), and the phosphonium rhodamine compound (Example 4) were measured. For the measurement of the phosphonium fluorescein compound (Example 1), a sample solution prepared by dissolving the phosphonium fluorescein compound (Example 1) in water (pH 7.1) at a concentration of 5.0×10 -5 M was used. For the measurement of the phosphonium rhodol compound (Example 3), a sample solution prepared by dissolving the phosphonium rhodol compound (Example 3) in water (pH 7.0) containing 10% by mass of dimethyl sulfoxide (DMSO) at a concentration of 5.0×10 -5 M was used. For the measurement of the phosphonium rhodamine compound (Example 4), a sample solution prepared by dissolving the phosphonium rhodamine compound (Example 4) in water (pH 5.3) at a concentration of 1.0×10 -5 M was used. Using each sample solution, the measurement was carried out with a Shimadzu UV - 3150 spectrometer. Also, the fluorescence spectrum was measured with a HITACHI F - 4500 spectrometer using each sample solution. The results are shown in FIGS. 2 - 4. In FIGS. 2 - 4, the left side is the absorption spectrum and the right side is the fluorescence spectrum.

[0189] Test Example 2: Evaluation of solvent dependence of fluorescence The absorption spectrum and fluorescence spectrum of the phosphonium fluorescein compound (Example 1) were measured in various solvents. As the solvents, methanol, acetonitrile, dimethyl sulfoxide, dichloromethane, and toluene were used, and the concentration of the phosphonium fluorescein compound (Example 1) was 5.0×10 -5As M, the absorption spectrum and fluorescence spectrum were measured in the same manner as in Test Example 1 above. The results are shown in FIG. 5 and Table 1.

[0190]

Table 1

Claims

1. A phosphonium compound or a salt, hydrate or solvate thereof containing an ion represented by the general formula (1): 【Chemical 1】 [wherein, Y １ represents an oxygen atom or a substituted or unsubstituted amino cation. Y ２ represents an oxygen anion or a substituted or unsubstituted amino group. R １ and R ２ are the same or different and each represents a substituted or unsubstituted (hetero)aryl group or a substituted or unsubstituted alkyl group. R ３ and R ４ are the same or different and each represents a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted alkoxy group. However, at least one of R ３ and R ４ is a substituted or unsubstituted alkyl group or a substituted or unsubstituted alkoxy group. R ５ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, or a substituted or unsubstituted aryl group. R ６ , R ７ , R ８ and R ９ are the same or different and each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a sulfonic acid group. At least one selected from the group consisting of R ６ and Y １ , R ７ and Y ２ , R ８ and Y １ , and R ９ and Y ２ may together form a substituted or unsubstituted alkylene group. ]

2. The phosphonium compound or a salt, hydrate or solvate thereof according to claim 1, containing a phosphonium rhodamine cation represented by the general formula (1A):

3. [[Chemical Formula 2]] [wherein, R １ , R ２ , R ３ , R ４ and R ５ are the same as described above. R ６ａ , R ７ａ , R ８ａ and R ９ａ are the same or different and each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a sulfonic acid group. R １０ , R １１ , R １２ａ and R １３ａ are the same or different and each represents a substituted or unsubstituted alkyl group. At least one selected from the group consisting of R ６ａ and R １０ , R ７ａ and R １３ａ , R ８ and R １１ , and R ９ and R １２ａ may together form a substituted or unsubstituted alkylene group.] The phosphonium compound or a salt, hydrate or solvate thereof according to claim 2, having an absorption maximum wavelength of 690 to 730 nm in water.

4. The phosphonium compound or a salt, hydrate or solvate thereof according to claim 1, which is a phosphonium fluorescein compound represented by the general formula (1B) or a salt, hydrate or solvate thereof:

5. The phosphonium compound or a salt, hydrate or solvate thereof according to claim 4, having an absorption maximum wavelength of 630 to 660 nm in water. [Chemical Formula 3] [wherein, R １ , R ２ , R ３ , R ４ , and R ５ are the same as described above. R ６ｂ , R ７ｂ , R ８ｂ , and R ９ｂ are the same as or different from each other, and each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a sulfonic acid group. ]

6. The phosphonium compound or a salt, hydrate or solvate thereof according to claim 1, containing a phosphonium rhodol cation represented by the general formula (1C):

7. The phosphonium compound or a salt, hydrate or solvate thereof according to claim 6, having an absorption maximum wavelength of 660 to 690 nm in water.

8. 【Chemical Formula 4】 [wherein, R １ , R ２ , R ３ , R ４ and R ５ are the same as described above. R ６ｃ , R ７ｃ , R ８ｃ and R ９ｃ are the same or different and each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a sulfonic acid group. R １２ｃ and R １３ｃ are the same or different and each represents a substituted or unsubstituted alkyl group. At least one selected from the group consisting of R ７ｃ and R １３ｃ , and R ９ｃ and R １２ｃ may together form a substituted or unsubstituted alkylene group. ]

9.

10. A fluorescent dye containing the phosphonium compound or a salt, hydrate or solvate thereof according to any one of claims 1 to 9.

11. Said R ５ , R ６ , R ７ , R ８ and R ９ are all hydrogen atoms, the phosphonium compound or its salt, hydrate or solvate according to any one of claims 1 to 7. A solvatochromic fluorescent dye containing the phosphonium compound or a salt, hydrate or solvate thereof according to any one of claims 1 to 9, and wherein the phosphonium compound or a salt thereof is a phosphonium fluorescein compound represented by the general formula (1B) or a salt, hydrate or solvate thereof: R １ and R ２ are the same or different and are a substituted or unsubstituted aryl group, the phosphonium compound or a salt, hydrate or solvate thereof according to any one of claims 1 to 8.

12. The solvatochromic fluorescent dye according to claim 11, which is a negative solvatochromic fluorescent dye. ​ ​ 【Chemical Formula 5】 [wherein, R １ , R ２ , R ３ , R ４ and R ５ are the same as defined above. R ６ｂ , R ７ｂ , R ８ｂ and R ９ｂ are the same as or different from each other, and each represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or a sulfonic acid group. ] ​ ​ ​

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