Compound

Abstract

A compound is represented by formula (1) (in formula (1), wavy lines 1 and 2 respectively represent bonding positions with wavy lines 1 and 2 in any of the structures represented by formulas (1-1) to (1-4), and wavy lines 3 and 4 respectively represent bonding positions with wavy lines 3 and 4 in any of the structures represented by formulas (1-5) to (1-8)).

Description

compound

[0001] The present disclosure relates to compounds.

[0002] Visualization of intracellular microenvironments using fluorescent dye compounds is an important technique widely used in everything from basic research to clarifying biological phenomena to clinical research such as disease-specific imaging. pH is one of the triggers for the manifestation of the most fundamental biological phenomena. Specifically, the pH gradient is used for protein transport from the endoplasmic reticulum to the Golgi apparatus, and a decrease in pH promotes maturation from endosomes to lysosomes. Furthermore, in cancer cells, increased anaerobic glycolysis reduces pH, significantly affecting the intracellular microenvironment.

[0003] As mentioned above, even slight changes in pH affect the vital activities of various cells, making it essential to have a technique for measuring intracellular pH. In recent years, various pH-sensitive fluorescent dye compounds have been developed and used to measure local intracellular pH. For example, a fluorescent dye for measuring intracellular pH is disclosed in Patent Document 1. The fluorescence intensity of this compound is known to change depending on pH, and pH is estimated by determining the ratio of fluorescence intensities at two excitation wavelengths at a specific pH.

[0004] JP 2016-193897 A

[0005] The pH measurement method using a fluorescent dye compound disclosed in Patent Document 1 is currently considered to be the only method capable of measuring intracellular pH. However, the development of compounds having fluorescent properties and pH sensitivity that can be used in this method is insufficient, and development that expands the selection of compounds that can be used in this method is desired. Therefore, an objective of the present disclosure is to provide novel compounds having fluorescent properties and pH sensitivity, derivatives of these compounds, and novel compounds that can be used to synthesize these compounds.

[0006] As a result of extensive research, the inventors of the present disclosure discovered that a specific structure can exhibit fluorescent properties and pH sensitivity, and arrived at the present disclosure.

[0007] That is, the gist of the present disclosure is as follows: [1] A compound represented by the following formula (1): (In the above formula (1), R １ ~R ４ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １ ~R ４ at least one of is a hydroxy group, wavy lines 1 and 2 represent bonding positions with wavy lines 1 and 2 in any of the structures represented by the following formulas (1-1) to (1-4), respectively, and wavy lines 3 and 4 represent bonding positions with wavy lines 3 and 4 in any of the structures represented by the following formulas (1-5) to (1-8), respectively. (In the above formulas (1-1) to (1-4), R １１ ~R １４ , R ２１ ~R ２６ , R ３１ ~R ３６ , and R ４１ ~R ４６ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １１ ~R １４ At least one of R is a hydroxy group; ２１ ~R ２６ At least one of R is a hydroxy group; ３１ ~R ３６ At least one of R is a hydroxy group; ４１ ~R ４６At least one of the groups is a hydroxy group, and the wavy lines 1 and 2 represent the bonding positions with the wavy lines 1 and 2 in the formula (1), respectively. (In the above formulas (1-5) to (1-8), R ５１ ~R ５４ , R ６１ ~R ６６ , R ７１ ~R ７６ , and R ８１ ~R ８６ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R ５１ ~R ５４ At least one of R is a hydroxy group; ６１ ~R ６６ At least one of R is a hydroxy group; ７１ ~R ７６ At least one of R is a hydroxy group; ８１ ~R ８６ At least one of the R is a hydroxy group, and the wavy lines 3 and 4 represent the bonding positions with the wavy lines 3 and 4 in the formula (1), respectively. １２ is a hydroxy group, and ２２ ~R ２４ At least one of the R ３１ ~R ３４ At least one of the R ４１ , R ４２ and R ４５ At least one of the R ５２ is a hydroxy group, and ６２ ~R ６４ At least one of the R ７１ ~R ７４At least one of the R ８１ , R ８２ and R ８５ [3] The compound according to [1], wherein at least one of the R １ ~R ４ [4] The compound according to any one of [1] to [3], wherein the structures represented by formulas (1-1) to (1-4) are structures represented by the following formulas (1-1-1) to (1-4-3): [5] The compound according to any one of [1] to [4], wherein the structure represented by the formulas (1-5) to (1-8) is a structure represented by the following formulas (1-5-1) to (1-8-3): [6] The compound according to any one of [1] to [5], represented by the following formula (4): (In the above formula (4), R １ ~R ４ are R in the above formula (1), respectively. １ ~R ４ is synonymous with R １１ ~R １４ are R in the above formula (1-1), respectively. １１ ~R １４ is synonymous with R ７１ , R ７２ , and R ７４ ~R ７６ are R in the above formula (1-7), respectively. ７１ , R ７２ , and R ７４ ~R ７６ [7] The compound according to any one of [1] to [6], which is a pH indicator. [8] A compound represented by the following formula (3): (In the above formula (3), R １ａ ~R ４ａ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 1 to 10 carbon atoms which may have a substituent, or -OR ｍ１and —CH 3 contained in the alkyl group or aryl group. ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, ｍ１ represents an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １ａ ~R ４ａ At least one of the ｍ１ The wavy lines 1a and 2a represent bonding positions with the wavy lines 1a and 2a in any of the structures represented by the following formulas (3-1) to (3-4), respectively. The wavy lines 3a and 4a represent bonding positions with the wavy lines 3a and 4a in any of the structures represented by the following formulas (3-5) to (3-8), respectively. (In the above formulas (3-1) to (3-4), R １１ａ ~R １４ａ , R ２１ａ ~R ２６ａ , R ３１ａ ~R ３６ａ , and R ４１ ~R ４６ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 1 to 10 carbon atoms which may have a substituent, or -OR ｍ２ and —CH in the alkyl group or aryl group. ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １１ａ ~R １４ａ At least one of the ｍ２ and R ２２ａ ~R ２６ａ At least one of the ｍ２ and R ３１ａ ~R ３６ａ At least one of the ｍ２ and R ４１ａ ~R４６ａ At least one of the ｍ２ The wavy lines 1a and 2a represent the bonding positions with the wavy lines 1a and 2a in the above formula (3), respectively. (In the above formulas (3-5) to (3-8), R ５１ａ ~R ５４ａ , R ６１ａ ~R ６６ａ , R ７１ａ ~R ７６ａ , and R ８１ａ ~R ８６ａ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 1 to 10 carbon atoms which may have a substituent, or -OR ｍ３ and —CH in the alkyl group or aryl group. ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R ５１ａ ~R ５４ａ At least one of the ｍ３ and R ６１ａ ~R ６６ａ At least one of the ｍ３ and R ７１ａ ~R ７６ａ At least one of the ｍ３ and R ８１ａ ~R ８６ａ At least one of the ｍ３ The wavy lines 3a and 4a represent the bonding positions with the wavy lines 3a and 4a in the formula (3), respectively. [9] A compound represented by the following formula (2): (In the above formula (2), R １ｂ ~R ４ｂ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２- may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １ｂ ~R ４ｂ At least one of is a hydroxy group, and the wavy line 5 represents the bonding position with the wavy line 5 in any of the structures represented by the following formulas (2-1) to (2-3). (In the above formulas (2-1) to (2-3), R １１ｂ ~R １４ｂ , R ２１ｂ ~R ２６ｂ , and R ３１ｂ ~R ３６ｂ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １１ｂ ~R １４ｂ At least one of R is a hydroxy group; ２１ｂ ~R ２６ｂ At least one of R is a hydroxy group; ３１ｂ ~R ３６ｂ At least one of is a hydroxy group, and the wavy line 5 represents the bonding position with the wavy line 5 in the above formula (2).

[0008] The present disclosure can provide novel compounds having fluorescent properties and pH sensitivity, derivatives of the compounds, and novel compounds that can be used to synthesize the compounds.

[0009] Graphs showing the relationship between pH and fluorescence intensity, excitation spectra, and fluorescence spectra in solutions containing Compounds 3 and 4 used in the Examples. Graphs showing the relationship between pH and fluorescence intensity, excitation spectra, and fluorescence spectra in solutions containing Compounds 7a and 7b used in the Examples. Graphs showing the relationship between pH and fluorescence intensity, excitation spectra, and fluorescence spectra in solutions containing Compounds 8a and 8b used in the Examples. Graphs showing the relationship between pH and fluorescence intensity, excitation spectra, and fluorescence spectra in solutions containing Compounds 9 and 10 used in the Examples. Graphs showing the relationship between pH and fluorescence intensity, excitation spectra, and fluorescence spectra in solutions containing Compounds 11a and 11b used in the Examples. Graphs showing the relationship between pH and fluorescence intensity, excitation spectra, and fluorescence spectra in solutions containing Compounds 15a and 15b used in the Examples. Graphs showing the relationship between pH and fluorescence intensity, excitation spectra, and fluorescence spectra in solutions containing Compounds 16a and 16b used in the Examples. 1 shows a graph showing the relationship between pH and fluorescence intensity, excitation spectrum, and fluorescence spectrum in a solution containing Compound 17 and Compound 18 used in the Examples. 1 shows a graph showing the relationship between pH and fluorescence intensity, excitation spectrum, and fluorescence spectrum in a solution containing Compound 17 and Compound 18 used in the Examples. 1 shows a graph showing the relationship between pH and fluorescence intensity, excitation spectrum, and fluorescence spectrum in a solution containing Compound 19a and Compound 19b used in the Examples. 1 shows a graph showing the relationship between pH and fluorescence intensity, excitation spectrum, and fluorescence spectrum in a solution containing Compound 20a and Compound 20b used in the Examples. 1 shows a graph showing the relationship between pH and fluorescence intensity, excitation spectrum, and fluorescence spectrum in a solution containing Compound 20a and Compound 20b used in the Examples. 1 shows a graph showing the relationship between pH and fluorescence intensity, excitation spectrum, and fluorescence spectrum in a solution containing Compound 21a and Compound 21b used in the Examples. 1 shows a graph showing the relationship between pH and fluorescence intensity, excitation spectrum, and fluorescence spectrum in a solution containing Compound 22a and Compound 22b used in the Examples.Graphs showing the relationship between pH and fluorescence intensity, excitation spectra, and fluorescence spectra for solutions containing compounds 23a and 23b used in the Examples. Camera images (photographs) showing fluorescence emitted by irradiating excitation light onto a solution containing compounds 3 and 4 in the Examples. Camera images (photographs) showing fluorescence emitted by irradiating excitation light onto a solution containing compounds 7a and 7b in the Examples. Camera images (photographs) showing fluorescence emitted by irradiating excitation light onto a solution containing compounds 8a and 8b in the Examples. Camera images (photographs) showing fluorescence emitted by irradiating excitation light onto a solution containing compounds 9 and 10 in the Examples. Camera images (photographs) showing fluorescence emitted by irradiating excitation light onto a solution containing compounds 11a and 11b in the Examples. Camera images (photographs) showing fluorescence emitted by irradiating excitation light onto a solution containing compounds 15a and 15b in the Examples. 1 shows camera images (photographs as a substitute for a drawing) of fluorescence emitted by irradiating excitation light onto a solution containing Compound 17 and Compound 18 in an example. 2 shows green and red fluorescent images, as well as a merged image of the green and red fluorescent images, of HeLa cells stained with Compound 25 in an example.

[0010] The following describes in detail embodiments of the present disclosure, but these descriptions are merely examples (representative examples) of embodiments of the present disclosure, and the present disclosure is not limited to these details as long as they do not depart from the gist of the disclosure. In this disclosure, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits, and "A to B" means A or greater and B or less. In addition, in this disclosure, when it is written as "C or greater, D or less," these can be treated as separate numerical ranges. Furthermore, when the lower limit and upper limit of a numerical range are stated separately, the numerical range can be a combination of any of the lower limit and any of the upper limit. Furthermore, although multiple embodiments are described in this disclosure, various conditions in each embodiment can be applied to each other within the applicable range.

[0011] <Compound> [Constitution of Compound] A compound according to one embodiment of the present disclosure (hereinafter also referred to as "compound A") is a compound represented by the following formula (1).

[0012]

[0013] In the above formula (1), R １ ~R ４ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １ ~R ４ at least one of is a hydroxy group, wavy lines 1 and 2 represent bonding positions with wavy lines 1 and 2 in any of the structures represented by formulas (1-1) to (1-4) described below, respectively, and wavy lines 3 and 4 represent bonding positions with wavy lines 3 and 4 in any of the structures represented by formulas (1-5) to (1-8) described below, respectively.

[0014] In the present disclosure, the number of carbon atoms in the alkyl group may be 1 to 10, 1 to 8, 1 to 5, or 1 to 3. In addition, the alkyl group may be linear, branched, or have a ring structure.

[0015] In the present disclosure, the number of carbon atoms in the aryl group may be 1 to 10, 1 to 8, or 1 to 6. The aromatic ring contained in the aryl group may be an aromatic heterocycle or a fused polycyclic aromatic ring. In the present disclosure, the aryl group is preferably an aryl group having a monocyclic aromatic hydrocarbon ring that does not contain a heteroatom.

[0016] In the present disclosure, the optional substituent is a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, or a thiol group.

[0017] R１ ~R ４ are each independently preferably a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, or an alkyl group having 1 to 10 carbon atoms which may have a substituent, more preferably a hydrogen atom, a hydroxy group, or a carboxy group, and even more preferably a hydrogen atom or a hydroxy group. １ ~R ４ The number of hydroxy groups in R is not particularly limited, and may be 2 or more, 3 or more, or 4, or may be 3 or less, 2 or less, or 1. １ ~R ４ The number of hydroxy groups in R may be 1, 2, 3, or 4, and may be 1 to 2, 2 to 4, 2 to 4, or 3 to 4, and is preferably 1. １ ~R ４ About R １ ~R ４ It is preferable that at least one of R is a carboxy group. １ ~R ４ The number of carboxy groups in R is not particularly limited, and may be 1 or more, 2 or more, or 3, or may be 3 or less, 2 or less, or 1. １ ~R ４ The combination of is not particularly limited, but for example, in the case of an embodiment containing one hydroxy group and one carboxy group, (R １ , R ２ , R ３ , R ４) = (hydroxy group, carboxy group, hydrogen atom, hydrogen atom), (hydroxy group, hydrogen atom, carboxy group, hydrogen atom), (hydroxy group, hydrogen atom, hydrogen atom, carboxy group), (carboxy group, hydroxy group, hydrogen atom, hydrogen atom), (hydrogen atom, hydroxy group, carboxy group, hydrogen atom), (hydrogen atom, hydroxy group, hydrogen atom, carboxy group), (carboxy group, hydrogen atom, hydroxy group, hydrogen atom), (hydrogen atom, carboxy group, hydroxy group, hydrogen atom), (carboxy group, hydrogen atom, hydroxy group, hydrogen atom), (hydrogen atom, hydrogen atom, hydroxy group, carboxy group), (carboxy group, hydrogen atom, hydrogen atom, hydroxy group), (hydrogen atom, carboxy group, hydrogen atom, hydroxy group), or (hydrogen atom, hydrogen atom, carboxy group, hydroxy group). １ ~R ４ For example, in an embodiment containing one hydroxy group, the combinations of (hydroxy group, hydrogen atom, hydrogen atom, hydrogen atom), (hydrogen atom, hydroxy group, hydrogen atom, hydrogen atom), (hydrogen atom, hydrogen atom, hydroxy group, hydrogen atom), or (hydrogen atom, hydrogen atom, hydrogen atom, hydroxy group) may be used.

[0018]

[0019] In the above formulas (1-1) to (1-4), R １１ ~R １４ , R ２１ ~R ２６ , R ３１ ~R ３６ , and R ４１ ~R ４６ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １１ ~R １４ At least one of R is a hydroxy group; ２１ ~R２６ At least one of R is a hydroxy group; ３１ ~R ３６ At least one of R is a hydroxy group; ４１ ~R ４６ At least one of the groups is a hydroxy group, and the wavy lines 1 and 2 represent the bonding positions with the wavy lines 1 and 2 in the above formula (1), respectively.

[0020] In the technical field, few compounds have been developed that emit fluorescence only in a very limited pH range, and in particular, few compounds have been reported that emit fluorescence only in the neutral range. As a result of extensive research, the inventors of the present disclosure have discovered that the above-described compound A emits fluorescence when irradiated with excitation light of a specific wavelength, and that the fluorescence intensity changes depending on the pH. The above-described compound A emits fluorescence over a partial or entire pH range (e.g., a partial or entire pH range of 1 to 14; a pH range corresponding to the neutral range; etc.). The pH range in which compound A emits fluorescence and the fluorescence intensity, among other fluorescent aspects, can be controlled by selecting the structure. Therefore, according to the present disclosure, a compound that emits a desired fluorescence in a desired pH range can be provided. Thus, compound A has the properties of a pH-sensitive dye, and can be used as a pH indicator.

[0021] More specific embodiments of the above formula (1) are described below. １１ ~R １４ , R ２１ ~R ２６ , R ３１ ~R ３６ , and R ４１ ~R ４６ are each independently preferably a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, or an alkyl group having 1 to 10 carbon atoms which may have a substituent, and more preferably a hydrogen atom or a hydroxy group. １１ ~R １４ About R １２ is preferably a hydroxy group, and R １２ It is more preferable that R is a hydroxy group and the others are hydrogen atoms. ２１ ~R２６ About R ２２ ~R ２４ Preferably, at least one of R is a hydroxy group. ２２ ~R ２４ It is more preferable that at least one of R is a hydroxy group and the others are hydrogen atoms. ２３ It is more preferable that R is a hydroxy group and the others are hydrogen atoms. ３１ ~R ３６ About R ３１ ~R ３４ Preferably, at least one of R is a hydroxy group. ３１ ~R ３４ It is more preferable that at least one of R is a hydroxy group and the others are hydrogen atoms. ３１ ~R ３４ It is more preferable that one of R is a hydroxy group and the others are hydrogen atoms. ４１ ~R ４６ About R ４１ , R ４２ and R ４５ Preferably, at least one of R is a hydroxy group. ４１ , R ４２ and R ４５ It is more preferable that at least one of R is a hydroxy group and the others are hydrogen atoms. ４１ , R ４２ and R ４５ It is more preferable that one of the groups is a hydroxy group and the others are hydrogen atoms.

[0022] The structures represented by the above formulas (1-1) to (1-4) are preferably structures represented by the following formulas (1-1-1) to (1-4-3).

[0023]

[0024]

[0025] In the above formulas (1-5) to (1-8), R ５１ ~R ５４ , R ６１ ~R ６６ , R ７１~R ７６ , and R ８１ ~R ８６ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R ５１ ~R ５４ At least one of R is a hydroxy group; ６１ ~R ６６ At least one of R is a hydroxy group; ７１ ~R ７６ At least one of R is a hydroxy group; ８１ ~R ８６ At least one of the groups is a hydroxy group, and the wavy lines 3 and 4 represent the bonding positions with the wavy lines 3 and 4 in the above formula (1), respectively.

[0026] R ５１ ~R ５４ , R ６１ ~R ６６ , R ７１ ~R ７６ , and R ８１ ~R ８６ are each independently preferably a hydrogen atom, a halogen atom, a hydroxy group, a carboxy group, or an alkyl group having 1 to 10 carbon atoms which may have a substituent, and more preferably a hydrogen atom or a hydroxy group. ５１ ~R ５４ About R ５２ is preferably a hydroxy group, and R ５２ It is more preferable that R is a hydroxy group and the others are hydrogen atoms. ６１ ~R ６６ About R ６２ ~R ６４ Preferably, at least one of R is a hydroxy group. ６２ ~R ６４It is more preferable that at least one of R is a hydroxy group and the others are hydrogen atoms. ６３ It is more preferable that R is a hydroxy group and the others are hydrogen atoms. ７１ ~R ７６ About R ７１ ~R ７４ Preferably, at least one of R is a hydroxy group. ７１ ~R ７４ It is more preferable that at least one of R is a hydroxy group and the others are hydrogen atoms. ７１ ~R ７４ It is more preferable that one of R is a hydroxy group and the others are hydrogen atoms. ８１ ~R ８６ About R ８１ , R ８２ and R ８５ Preferably, at least one of R is a hydroxy group. ８１ , R ８２ and R ８５ It is more preferable that at least one of R is a hydroxy group and the others are hydrogen atoms. ８１ , R ８２ and R ８５ It is more preferable that one of the groups is a hydroxy group and the others are hydrogen atoms.

[0027] The structures represented by the above formulas (1-5) to (1-8) are preferably structures represented by the following formulas (1-5-1) to (1-8-3).

[0028]

[0029] Examples of the combination of the structure represented by any one of formulas (1-1) to (1-4) in formula (1) with the structure represented by any one of formulas (1-5) to (1-8) include a combination of the structure represented by formula (1-1) with the structure represented by formula (1-5), a combination of the structure represented by formula (1-1) with the structure represented by formula (1-6), a combination of the structure represented by formula (1-1) with the structure represented by formula (1-7), a combination of the structure represented by formula (1-1) with the structure represented by formula (1-8), a combination of the structure represented by formula (1-2) with the structure represented by formula (1-6), a combination of the structure represented by formula (1-3) with the structure represented by formula (1-7), and a combination of the structure represented by formula (1-4) with the structure represented by formula (1-8). The combination of the structure represented by any one of formulas (1-1) to (1-4) and the structure represented by any one of formulas (1-5) to (1-8) in formula (1) includes a combination of the structure represented by formula (1-1-1) and the structure represented by formula (1-5-1), a combination of the structure represented by formula (1-1-1) and the structure represented by formula (1-6-2), a combination of the structure represented by formula (1-1-1) and the structure represented by formula (1-6-3), a combination of the structure represented by formula (1-1-1) and the structure represented by formula (1-7-1), a combination of the structure represented by formula (1-1-1) and the structure represented by formula (1-7-2), a combination of the structure represented by formula (1-1-1) and the structure represented by formula (1-7-3), a combination of the structure represented by formula (1-1-1) A combination of a structure represented by the formula (1-7-4), a combination of a structure represented by the formula (1-1-1) and a structure represented by the formula (1-8-1), a combination of a structure represented by the formula (1-1-1) and a structure represented by the formula (1-8-2), a combination of a structure represented by the formula (1-2-2) and a structure represented by the formula (1-6-2), a combination of a structure represented by the formula (1-3-1) and a structure represented by the formula (1-7-1), a combination of a structure represented by the formula (1-3-3) and a structure represented by the formula (1-7-3), a combination of a structure represented by the formula (1-3-4) and a structure represented by the formula (1-7-4), or a combination of a structure represented by the formula (1-4-2) and a structure represented by the formula (1-8-2).

[0030] In the technical field, dye compounds (one-excitation, one-fluorescence compounds) that emit one type of fluorescence at one specific wavelength are known, and the above-described compound A basically has this property. As a result of further intensive research, the inventors of the present disclosure have found that, among the above-described compounds A, a specific compound (two-excitation, two-fluorescence compounds) emits two types of fluorescence at two specific wavelengths. While one-excitation, one-fluorescence compounds can measure pH, they emit only one type of fluorescence and produce this fluorescence over a wide pH range. Therefore, further improvements are expected from the perspective of determining accurate pH. On the other hand, two-excitation, two-fluorescence compounds emit two types of fluorescence, and the intensities of the two types of fluorescence change with pH, ​​so the color of the fluorescence changes with changes in pH. Therefore, more accurate pH measurement is possible than with one-excitation, one-fluorescence compounds.

[0031] Specifically, the two-excitation two-fluorescence compound is a compound represented by the following formula (4).

[0032]

[0033] In the above formula (4), R １ ~R ４ are R in the above formula (1), respectively. １ ~R ４ is synonymous with R １１ ~R １４ are R in the above formula (1-1), respectively. １１ ~R １４ is synonymous with R ７１ , R ７２ , and R ７４ ~R ７６ are R in the above formula (1-7), respectively. ７１ , R ７２ , and R ７４ ~R ７６ is synonymous with.

[0034] Specifically, in the above formula (4), R １１ , R １３ , R １４ , and R ７１ , R ７２ , and R ７４ ~R ７６ is a hydrogen atom, R １２is a hydroxy group, and R １ ~R ４ The inventors of the present disclosure have confirmed that Compound A, in which at least one of the groups is a hydroxy group and the others are hydrogen atoms, exhibits a maximum excitation wavelength / maximum fluorescence wavelength of 515 nm / 540 nm for yellow-green fluorescence and a maximum excitation wavelength / maximum fluorescence wavelength of 535 nm / 615 nm for red fluorescence, and is a compound having independent excitation and fluorescence wavelengths. Compound A exhibits significant changes in fluorescence intensity, particularly between pH 7 and 8, and therefore has properties suitable for biological imaging. Furthermore, the fluorescence emitted by Compound A has wavelengths that can be detected using green and red dichroic mirrors used in general fluorescence microscopes, and therefore Compound A can be suitably used for measuring intracellular pH without the need for special mirrors or devices.

[0035] [Method for producing compound A] The method for producing the above-mentioned compound A is not particularly limited. An example of the production method is shown below, but the present invention is not limited to this method. In the following production method, R １ｂ ~R ４ｂ are R in formula (2) described later. １ｂ ~R ４ｂ and R in the formula in the following production method １１ｂ ~R １４ｂ are R in formula (2-1) described later. １１ｂ ~R １４ｂ and R in the formula in the following production method ７１ ~R ７６ are R in the above formula (1-7), respectively. ７１ ~R ７６ is synonymous with.

[0036]

[0037] (Step 1) Step 1 is a step in which compound A represented by formula (A-1) is used as a raw material and subjected to a treatment such as heating to obtain a compound represented by formula (A-2). When a commercially available product of the compound represented by formula (A-2) is available, step 1 may be omitted and step 2 may be performed using the commercially available product. Hereinafter, the compound represented by formula (X) will also be referred to as "compound (X)." The method for obtaining compound (A-1) is not particularly limited, and a compound obtained by synthesis using a known method may be used, or a commercially available product may be used. The method for obtaining compound (A-2) from compound (A-1) is not particularly limited, and a known method such as heating may be applied. Note that a solvent may or may not be used in the reaction of step 1.

[0038] The reaction conditions are not particularly limited, but the heating temperature may typically be 160 to 200° C., 150 to 215° C., 140 to 230° C., or 120 to 250° C. The heating time is typically 6 to 72 hours, preferably 10 to 48 hours, more preferably 12 to 36 hours, and even more preferably 15 to 30 hours.

[0039] (Step 2) Step 2 is a step in which compound (A-2) and compound (A-3) are reacted in the presence of an acid, if necessary in a solvent inert to the reaction, to obtain compound (A-4a) and compound (A-4b). The method for obtaining compound (A-3) is not particularly limited, and a compound obtained by synthesis using a known method may be used, or a commercially available product may be used. Examples of the acid include organic acids such as formic acid, methanesulfonic acid, ethanesulfonic acid, p-toluenesulfonic acid, acetic acid, propionic acid, lactic acid, citric acid, fumaric acid, malic acid, succinic acid, salicylic acid, maleic acid, glycerophosphoric acid, tartaric acid, benzoic acid, glutamic acid, aspartic acid, benzenesulfonic acid, naphthalenesulfonic acid, hexanoic acid, and acetylsalicylic acid; inorganic acids such as hydrochloric acid, hydrobromic acid, orthophosphoric acid, nitric acid, phosphoric acid, and sulfuric acid; and mixtures of these acids.

[0040] The reaction conditions are not particularly limited, but the heating temperature is usually 50 to 180° C., preferably 60 to 120° C., more preferably 70 to 100° C., and even more preferably 80 to 90° C. The heating time is usually 2 minutes to 72 hours, preferably 1 to 48 hours, more preferably 3 to 36 hours, and even more preferably 6 to 24 hours.

[0041] The reaction product obtained by the reaction is a mixture of compound (A-4a) and compound (A-4b). These compounds can be separated into each other by, for example, recrystallization.

[0042] The obtained compounds (A-4a) and (A-4b) are one embodiment of the compounds described above, and by further going through the following step 3, compound B described below can be obtained.

[0043]

[0044] (Step 3) Step 3 is a step in which compound (A-4a) is reacted in the presence of a base, if necessary in a solvent inert to the reaction, to obtain compound (A-5a) and compound (A-5b). Compound (A-5a) and compound (A-5b) can also be obtained by using compound (A-4b) instead of compound (A-4a). Examples of the base include organic bases such as alkylammonium oxides, organometallic compounds, metal alkoxides, amines, and heterocyclic amines; inorganic bases such as sodium hydroxide, potassium hydroxide, sodium carbonate, calcium hydroxide, lithium hydroxide, sodium bicarbonate, and ammonium hydroxide; and mixtures of these bases.

[0045] The reaction conditions are not particularly limited, but the heating temperature is usually 50 to 180° C., preferably 60 to 120° C., more preferably 70 to 100° C., and even more preferably 80 to 90° C. The heating time is usually 24 to 120 hours, preferably 36 to 96 hours, more preferably 48 to 84 hours, and even more preferably 60 to 72 hours.

[0046] The reaction product obtained by the reaction is a mixture of compound (A-5a) and compound (A-5b). These compounds can be separated into each other by, for example, recrystallization.

[0047]

[0048] (Step 4) Step 4 is a step in which compound (A-5a) and compound (A-6) are reacted in the presence of an acid, if necessary in a solvent inert to the reaction, to obtain compound (A-7a) and compound (A-7b). Compound (A-7a) and compound (A-7b) can also be obtained by using compound (A-5b) instead of compound (A-5a). Examples of the acid include those exemplified as the acid used in step 2 above.

[0049] The reaction conditions are not particularly limited, but the heating temperature is usually 50 to 180° C., preferably 60 to 120° C., more preferably 70 to 100° C., and even more preferably 80 to 90° C. The heating time is usually 2 minutes to 72 hours, preferably 1 to 48 hours, more preferably 3 to 36 hours, and even more preferably 6 to 24 hours.

[0050] The reaction product obtained by the reaction is a mixture of compound (A-7a) and compound (A-7b). These compounds can be separated into each other by, for example, recrystallization.

[0051] In the above reaction, the type of compound A obtained can be changed by changing the types of compounds (A-1), (A-3), and (A-6).

[0052] In addition, as the compound (A-6), R ７３ is a hydroxy group, i.e., a compound obtained by using a compound in which R ７３ Compounds (A-7a) and (A-7b) in which is a hydroxy group are fluorescent dye compounds represented by the above formula (4).

[0053] [Uses of Compound A] Compound A can be called a fluorescent dye compound because it emits fluorescence when irradiated with excitation light of a specific wavelength. Compound A exhibits a property in which its fluorescence intensity changes depending on the pH, making it suitable for use as a pH indicator, particularly a pH indicator that emits light only when the solution is near neutral. Compound A can also be used as a fluorescent tracer, laser dye, etc. Compound A can also be used as a reagent for synthesizing other pH-dependent fluorescent dye compounds. Compound A can also be covalently bonded to any molecule via its structural backbone, potentially improving the identification (detection) sensitivity and separation ability of the molecule. Therefore, Compound A can also be used as a labeling agent. Therefore, Compound A is expected to be developed into a technology capable of precisely measuring local intracellular pH. Compound A can also be used as a general fluorescent dye. Therefore, Compound A can also be used in, for example, organic electroluminescence (EL) displays, solar cells, reflective vests, etc.

[0054] <Synthetic Intermediate> A compound according to another embodiment of the present disclosure (hereinafter also referred to as "compound B") is a compound represented by the following formula (2). Compound B is a synthetic intermediate that can be used in the synthesis of compound A represented by the above-mentioned formula (1). Specifically, in the above-mentioned method for producing compound A, compound B is a synthetic intermediate corresponding to compound (A-5a) and compound (A-5b).

[0055]

[0056] In the above formula (2), R １ｂ ~R ４ｂ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １ｂ ~R ４ｂAt least one of the groups is a hydroxy group, and the wavy line 5 represents the bonding position with the wavy line 5 in any of the structures represented by the following formulas (2-1) to (2-3).

[0057] R １ｂ ~R ４ｂ are R in the above formula (1), including the preferred ranges. １ ~R ４ is synonymous with.

[0058]

[0059] In the above formulas (2-1) to (2-3), R １１ｂ ~R １４ｂ , R ２１ｂ ~R ２６ｂ , and R ３１ｂ ~R ３６ｂ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １１ｂ ~R １４ｂ At least one of R is a hydroxy group; ２１ｂ ~R ２６ｂ At least one of R is a hydroxy group; ３１ｂ ~R ３６ｂ At least one of is a hydroxy group, and the wavy line 5 represents the bonding position with the wavy line 5 in the above formula (2).

[0060] R １１ｂ ~R １４ｂ , R ２１ｂ ~R ２６ｂ , and R ３１ｂ ~R ３６ｂ represents R in the above formulas (1-1) to (1-4), including the preferred ranges. １１ ~R １４ , R ２１ ~R ２６ , and R ３１ ~R ３６is synonymous with.

[0061] <Derivative> A compound according to another embodiment of the present disclosure (hereinafter also referred to as "compound C") is a compound represented by the following formula (3). Compound C is a derivative of the compound represented by the above formula (1), and specifically, a compound in which a hydrogen atom in at least one of the hydroxy groups bonded to a benzene ring or a naphthalene ring in compound A represented by formula (1) is substituted with another functional group (R ｍ１ , R ｍ２ , R ｍ３ ) is a compound in which

[0062]

[0063] In the above formula (3), R １ａ ~R ４ａ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 1 to 10 carbon atoms which may have a substituent, or -OR ｍ１ and —CH 3 contained in the alkyl group or aryl group. ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, ｍ１ represents an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １ａ ~R ４ａ At least one of the ｍ１ The wavy lines 1a and 2a represent bonding positions with the wavy lines 1a and 2a in any of the structures represented by the following formulas (3-1) to (3-4), respectively, and the wavy lines 3a and 4a represent bonding positions with the wavy lines 3a and 4a in any of the structures represented by the following formulas (3-5) to (3-8), respectively.

[0064] R １ａ ~R ４ａare each independently preferably a hydrogen atom, a halogen atom, a carboxy group, or an alkyl group having 1 to 10 carbon atoms which may have a substituent, and are each independently preferably a hydrogen atom, a hydroxy group, a carboxy group, or -OR ｍ１ is more preferred, and a hydrogen atom or —OR ｍ１ is more preferred. １ａ ~R ４ａ -OR in ｍ１ The number of R is not particularly limited, and may be 2 or more, 3 or more, 4, 3 or less, 2 or less, or 1. １ａ ~R ４ａ -OR in ｍ１ The number of R is 1, 2, 3 or 4, and may be 1 to 2, 2 to 4, 2 to 4, or 3 to 4, and is preferably 1. １ａ ~R ４ａ About R １ａ ~R ４ａ It is preferable that at least one of R is a carboxy group. １ａ ~R ４ａ The number of carboxy groups in R is not particularly limited, and may be 1 or more, 2 or more, or 3, or may be 3 or less, 2 or less, or 1. １ａ ~R ４ａ The combination of is not particularly limited, but for example, -OR ｍ１ and one carboxy group, (R １ａ , R ２ａ , R ３ａ , R ４ａ ) = (-OR ｍ１ , a carboxy group, a hydrogen atom, a hydrogen atom), (—OR ｍ１ , hydrogen atom, carboxy group, hydrogen atom), (—OR ｍ１ , hydrogen atom, hydrogen atom, carboxy group), (carboxy group, -OR ｍ１ , hydrogen atom, hydrogen atom), (hydrogen atom, -OR ｍ１ , carboxy group, hydrogen atom), (hydrogen atom, —OR ｍ１ , hydrogen atom, carboxy group), (carboxy group, hydrogen atom, -OR ｍ１, hydrogen atom), (hydrogen atom, carboxy group, -OR ｍ１ , hydrogen atom), (carboxy group, hydrogen atom, —OR ｍ１ , hydrogen atom), (hydrogen atom, hydrogen atom, -OR ｍ１ , carboxy group), (carboxy group, hydrogen atom, hydrogen atom, —OR ｍ１ ), (hydrogen atom, carboxy group, hydrogen atom, —OR ｍ１ ), or (hydrogen atom, hydrogen atom, carboxy group, -OR ｍ１ ) combinations may be used. １ａ ~R ４ａ The combination of is, for example, -OR ｍ１ In the case of an embodiment including one of (-OR ｍ１ , hydrogen atom, hydrogen atom, hydrogen atom), (hydrogen atom, -OR ｍ１ , hydrogen atom, hydrogen atom), (hydrogen atom, hydrogen atom, -OR ｍ１ , hydrogen atom), or (hydrogen atom, hydrogen atom, hydrogen atom, -OR ｍ１ ) combinations may be employed.

[0065]

[0066] In the above formulas (3-1) to (3-4), R １１ａ ~R １４ａ , R ２１ａ ~R ２６ａ , R ３１ａ ~R ３６ａ , and R ４１ ~R ４６ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 1 to 10 carbon atoms which may have a substituent, or -OR ｍ２ and —CH in the alkyl group or aryl group. ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １１ａ ~R １４ａ At least one of the ｍ２ and R ２１ａ ~R ２６ａ At least one of the ｍ２and R ３１ａ ~R ３６ａ At least one of the ｍ２ and R ４１ａ ~R ４６ａ At least one of the ｍ２ The wavy lines 1a and 2a represent the bonding positions with the wavy lines 1a and 2a in the formula (3), respectively.

[0067] R １１ａ ~R １４ａ , R ２１ａ ~R ２６ａ , R ３１ａ ~R ３６ａ , and R ４１ａ ~R ４６ａ are each independently a hydrogen atom, a halogen atom, a carboxy group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or -OR ｍ２ is preferred, and a hydrogen atom or —OR ｍ２ is more preferred. １１ａ ~R １４ａ About R １２ａ Ga-OR ｍ２ Preferably, R １２ａ Ga-OR ｍ２ and the remaining groups are hydrogen atoms. ２１ａ ~R ２６ａ About R ２２ａ ~R ２４ａ At least one of the groups is -OR ｍ２ Preferably, R ２２ａ ~R ２４ａ At least one of the groups is -OR ｍ２ and the remaining atoms are hydrogen atoms, and R ２３ａ Ga-OR ｍ２ and the remaining groups are hydrogen atoms. ３１ａ ~R ３６ａ About R ３１ａ ~R ３４ａ At least one of the groups is -OR ｍ２ Preferably, R ３１ａ ~R ３４ａ At least one of the groups is -OR ｍ２and the remaining atoms are hydrogen atoms, and R ３１ａ ~R ３４ａ Either of these is -OR ｍ２ and the remaining groups are hydrogen atoms. ４１ａ ~R ４６ａ About R ４１ａ , R ４２ａ and R ４５ａ At least one of the groups is -OR ｍ２ Preferably, R ４１ａ , R ４２ａ and R ４５ａ At least one of the groups is -OR ｍ２ and the remaining atoms are hydrogen atoms, and R ４１ａ , R ４２ａ and R ４５ａ Either of these is -OR ｍ２ and the remaining atoms are hydrogen atoms.

[0068] The structures represented by the above formulas (3-1) to (3-4) are preferably structures represented by the following formulas (3-1-1) to (3-4-3).

[0069]

[0070]

[0071] In the above formulas (3-5) to (3-8), R ５１ａ ~R ５３ａ , R ６１ａ ~R ６６ａ , R ７１ａ ~R ７６ａ , and R ８１ ~R ８６ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 1 to 10 carbon atoms which may have a substituent, or -OR ｍ３ and —CH in the alkyl group or aryl group. ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R ５１ａ ~R ５４ａAt least one of the ｍ３ and R ６１ａ ~R ６６ａ At least one of the ｍ３ and R ７１ａ ~R ７６ａ At least one of the ｍ３ and R ８１ａ ~R ８６ａ At least one of the ｍ３ The wavy lines 3a and 4a represent the bonding positions with the wavy lines 3a and 4a in the formula (3), respectively.

[0072] R ５１ａ ~R ５４ａ , R ６１ａ ~R ６６ａ , R ７１ａ ~R ７６ａ , and R ８１ａ ~R ８６ａ are each independently a hydrogen atom, a halogen atom, a carboxy group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or -OR ｍ３ is preferred, and a hydrogen atom or —OR ｍ３ is more preferred. ５１ａ ~R ５４ａ About R ５２ａ Ga-OR ｍ３ Preferably, R ５２ａ Ga-OR ｍ３ and the remaining groups are hydrogen atoms. ６１ａ ~R ６６ａ About R ６２ａ ~R ６４ａ At least one of the groups is -OR ｍ３ Preferably, R ６２ａ ~R ６４ａ At least one of the groups is -OR ｍ３ and the remaining atoms are hydrogen atoms, and R ６３ａ Ga-OR ｍ３ and the remaining groups are hydrogen atoms. ７１ａ ~R ７６ａ About R ７１ａ ~R ７４ａ At least one of the groups is -OR ｍ３Preferably, R ７１ａ ~R ７４ａ At least one of the groups is -OR ｍ３ and the remaining atoms are hydrogen atoms, and R ７１ａ ~R ７４ａ Either of these is -OR ｍ３ and the remaining groups are hydrogen atoms. ８１ａ ~R ８６ａ About R ８１ａ , R ８２ａ and R ８５ａ At least one of the groups is -OR ｍ３ Preferably, R ８１ａ , R ８２ａ and R ８５ａ At least one of the groups is -OR ｍ３ and the remaining atoms are hydrogen atoms, and R ８１ａ , R ８２ａ and R ８５ａ Either of these is -OR ｍ３ and the remaining atoms are hydrogen atoms.

[0073] The structures represented by the above formulas (3-5) to (3-8) are preferably structures represented by the following formulas (3-5-1) to (3-8-3).

[0074]

[0075] Examples of the combination of the structure represented by any one of formulas (3-1) to (3-4) and the structure represented by any one of formulas (3-5) to (3-8) in formula (3) include a combination of the structure represented by formula (3-1) and the structure represented by formula (3-5), a combination of the structure represented by formula (3-1) and the structure represented by formula (3-6), a combination of the structure represented by formula (3-1) and the structure represented by formula (3-7), a combination of the structure represented by formula (3-1) and the structure represented by formula (3-8), a combination of the structure represented by formula (3-2) and the structure represented by formula (3-6), a combination of the structure represented by formula (3-3) and the structure represented by formula (3-7), and a combination of the structure represented by formula (3-4) and the structure represented by formula (3-8). The combination of the structure represented by any one of formulas (3-1) to (3-4) and the structure represented by any one of formulas (3-5) to (3-8) in formula (3) is a combination of the structure represented by formula (3-1-1) and the structure represented by formula (3-5-1), a combination of the structure represented by formula (3-1-1) and the structure represented by formula (3-6-2), a combination of the structure represented by formula (3-1-1) and the structure represented by formula (3-6-3), a combination of the structure represented by formula (3-1-1) and the structure represented by formula (3-7-1), a combination of the structure represented by formula (3-1-1) and the structure represented by formula (3-7-2), a combination of the structure represented by formula (3-1-1) and the structure represented by formula (3-7-3), a combination of the structure represented by formula (3-1-1) A combination of a structure represented by the formula (3-7-4), a combination of a structure represented by the formula (3-1-1) and a structure represented by the formula (3-8-1), a combination of a structure represented by the formula (3-1-1) and a structure represented by the formula (3-8-2), a combination of a structure represented by the formula (3-2-2) and a structure represented by the formula (3-6-2), a combination of a structure represented by the formula (3-3-1) and a structure represented by the formula (3-7-1), a combination of a structure represented by the formula (3-3-3) and a structure represented by the formula (3-7-3), a combination of a structure represented by the formula (3-3-4) and a structure represented by the formula (3-7-4), or a combination of a structure represented by the formula (3-4-2) and a structure represented by the formula (3-8-2).

[0076] The compound C can be obtained, for example, by reacting the compound A represented by the formula (1) with another compound capable of reacting with a hydroxy group. For example, the following compound j, which is one embodiment of the compound A represented by the formula (1), is reacted with pivalic anhydride to obtain the following compound k.

[0077]

[0078] The present disclosure will be described in more detail below with reference to examples, but the present disclosure should not be construed as being limited to the following examples.

[0079] The following measuring instruments were used for each measurement in this example. Nuclear magnetic resonance spectrometer: JNM-ECZ 500R / SI (manufactured by JEOL Ltd.) or ECS400 (manufactured by JEOL Ltd.) Mass spectrometer: SIMADZE triple quadrupole mass spectrometer HPLC LCM8040 (manufactured by Shimadzu Corporation) Fluorescence spectrometer: Fluorescence spectrometer k FP-8300 (manufactured by JASCO Corporation) pH meter: LAQUA F-71 (Horiba, Ltd.) Confocal laser fluorescence microscope: LSM880 (manufactured by Carl Zeiss) or FV1000 (manufactured by Olympus Corporation)

[0080] <Synthesis of Compounds> [Synthesis 1]

[0081]

[0082] (Mixture of Compound 1 and Compound 2) 4-Hydroxyphthalic acid (1.82 g, 10 mmol) was dissolved in tetrahydrofuran (50 mL). The solvent was removed from the resulting solution under reduced pressure, and 4-hydroxyphthalic acid was deposited on the inner wall of a flask. 4-Hydroxyphthalic acid was heated in an oven at 150°C for 1 day and then cooled to room temperature while being vacuum dried. Resorcinol (2.21 g, 20 mmol) and methanesulfonic acid (15 mL) were added to the resulting solid, and the resulting reaction solution was stirred at 80°C for 1 day. The reaction mixture was cooled to room temperature, then mixed with ice (150 g) and stirred to produce a precipitate. This precipitate was collected by filtration and recrystallized from a mixed solvent of methanol (2 mL) and water (50 mL). Acetic anhydride (17 mL) was added to the resulting solid (2.35 g, 6.75 mmol) to prepare a solution, which was then refluxed at 80°C. The solvent was then distilled off from the reaction mixture under reduced pressure to obtain a crude product. This crude product was purified by silica gel column chromatography (dichloromethane → dichloromethane / ethyl acetate = 19:1) to obtain a mixture of Compound 1 and Compound 2 as a white powder (1.87 g, 71%). 1 H-NMR (500MHz, CDCl3) δ(ppm): 8.02-8.07(0.5H), 7.73-7.79(0.5H), 7.36-7.44(1H), 7.16-7.22(0.5H), 7.07-7.12(2H), 6.92-6.96(0.4H), 6.81-6.90(4H), 2.36-2.39(1.5H), 2.30-2.34(6H), 2.26-2.29(1H), 2.16-2.19(0.3H), 2.04-2.06(0.6H) ・ESI-MS (m / z) : 475 [M+H] +

[0083] (Mixture of Compounds 3 and 4) A 5M aqueous sodium hydroxide solution (7.2 mL), water (30 mL), and methanol (10 mL) were added to a mixture of Compounds 1 and 2 (561 mg, 1.2 mmol), and the resulting reaction solution was stirred at room temperature for 1 day. Concentrated hydrochloric acid was added to the reaction mixture, and the resulting precipitate was collected by filtration to obtain a mixture of Compounds 3 and 4 as a red powder (357 mg, 85%). 1H-NMR (500MHz, CDCl3) δ(ppm): 7.70(d, J=8.6Hz, 0.37H), 7.23(d, J=2.3Hz, 0.63H), 7.13(dd, J=8.0Hz, 2.3Hz, 0.63H), 7.01(d, J=8.0Hz, 0.63H), 6.95(dd, J=8.3Hz, 2.0Hz, 0.37H), 6.50-6.65(m, 6H), 6.33(d, J=1.7 Hz, 0.37H) ・ESI-MS (m / z): 349 [M+H] +

[0084] (Compounds 5 and 6) Pivalic anhydride (6 mL) was added to a mixture of compounds 3 and 4 (617 mg, 1.77 mmol), and the mixture was heated at 80° C. for 1 day. After the reaction mixture was cooled to room temperature, the solvent was removed from the solution under reduced pressure to obtain a crude product. The crude product was purified by silica gel column chromatography (dichloromethane → dichloromethane / ethyl acetate = 19:1) to obtain compound 5 as a white powder (245 mg, 23%) and compound 6 as a white powder (193 mg, 18%), respectively. Compound 5: 1 H-NMR (500MHz, CDCl3) δ(ppm): 7.74(d, J=2.3Hz, 1H), 7.39(dd, J=8.3Hz, 2.0Hz, 1H), 7.18(d, J=8.0Hz, 1H), 7.06(d, J=2.3Hz, 2H), 6.86(d,・ESI-MS (m / z): 601 [M+H] + Compound 6: ・ 1 H NMR (500MHz, CDCl3) δ(ppm): 8.04(d, J=8.6Hz, 1H), 7.36(dd, J=8.3Hz, 2.0Hz, 1H), 7.06(d, J=2.3Hz, 2H), 6.88(d, J=8.6Hz, 3H), 6.81(dd, J=8.6Hz, 2.3Hz, 2H), 1.37(s, 18H), 1.31(s, 9H). ・ESI-MS (m / z): 601 [M+H]+

[0085]

[0086] (Compound 3) Compound 5 (160 mg, 0.27 mmol) was added with 5 M aqueous sodium hydroxide solution (1.8 mL), water (30 mL), and methanol (10 mL), and the resulting reaction solution was stirred at room temperature for 1 day. Concentrated hydrochloric acid was added to the reaction mixture, and the resulting precipitate was collected by filtration to obtain compound 3 as a yellow powder (91 mg, 87%). 1 H NMR (500MHz, DMSO-d6) δ(ppm): 10.30(s, 1H), 10.06(s, 2H), 7.16 (td, J=9.5, 2.3 Hz, 2H), 7.03(d, J=8.6 Hz, 1H), 6.64(d, J=2.3Hz, 2H), 6.57-6.51(m, 4H). ・ESI-MS (m / z): 347 [MH] -

[0087] (Compound 4) Compound 6 (116 mg, 0.20 mmol) was hydrolyzed in the same manner as in the preparation of Compound 3 described above, to obtain Compound 4 as a yellow powder (67 mg, 96%). 1 H NMR (500MHz, DMSO-d6) δ(ppm): 8.10(t, J=8.3 Hz, 0.4H), 7.77(d, J=8.6Hz, 0.6H), 7.48(dd, J=8.3Hz, 2.0Hz, 0.4H), 7.25(dd, J=15.2Hz, 1.4Hz, 1H), 7.02(dd, J=8.3Hz, 2.0Hz, 0.6H), 6.94(s, 2H), 6.65(d, J=2.3Hz, 1H), 6.59-6.53(m, 2.4H), 6.39(d, J=1.7Hz, 0.6H).・ESI-MS (m / z): 347 [MH] -

[0088] [Synthesis 2] Hereinafter, dihydroxynaphthalene will be referred to as "DHN."

[0089]

[0090] (Mixture of Compound 7a and Compound 7b) 4-Hydroxyphthalic acid (181 mg, 0.99 mmol) was added to a flask and heated in an oven at 150°C for 1 day, then cooled to room temperature while drying under vacuum. 1,3-Dihydroxynaphthalene (320 mg, 2.0 mmol) and methanesulfonic acid (6 mL) were added to the resulting solid, and the resulting reaction solution was heated at 100°C for 1 day. The reaction mixture was cooled to room temperature, then mixed with ice (60 g) and stirred to produce a precipitate. This precipitate was collected by filtration to obtain 29 mg of a crude product. This crude product was purified by silica gel column chromatography (dichloromethane / methanol = 9:1 → dichloromethane / methanol = 4:1) to obtain a mixture of Compound 7a and Compound 7b as a pink powder (6 mg, 19%). 1 H NMR (500MHz, DMSO-d6) δ(ppm): 8.22-8.17(m, 7H), 7.14-7.10(m, 4H), 6.61(d, J=8.9Hz, 1H), 6.47(d, J=8.9Hz, 1H). ・ESI-MS (m / z): 449 [M+H] +

[0091] (Mixture of Compound 8a and Compound 8b) 4-Hydroxyphthalic acid (181 mg, 0.99 mmol) was dissolved in tetrahydrofuran (25 mL). The solvent was distilled off from the resulting solution under reduced pressure, and 4-hydroxyphthalic acid was deposited on the inner wall of the flask. 4-Hydroxyphthalic acid was heated in an oven at 120°C for 3 days and then cooled to room temperature while being dried under vacuum. 1,5-Dihydroxynaphthalene (321 mg, 2.0 mmol) and methanesulfonic acid (6 mL) were added to the resulting solid, and the resulting reaction solution was heated at 100°C for 1 day. The reaction mixture was cooled to room temperature, mixed with ice (60 g), and stirred to form a precipitate. This precipitate was collected by filtration to obtain 299 mg of a crude product. This crude product was purified by silica gel column chromatography (dichloromethane / methanol = 9:1) to obtain a mixture of Compound 8a and Compound 8b as a brown powder (8 mg, 3%). 1H NMR (500MHz, DMSO-d6) δ(ppm): 7.58(d, J=8.2Hz, 2H), 7.45(dd, J=8.4Hz, 7.2Hz, 2H), 7.25-7.23(m, 5H), 7.17(dd, J=8.5Hz, 2.3Hz, 1H), 6.96(d, J=7.3Hz, 3H). ・ESI-MS (m / z): 449 [M+H] +

[0092] (Mixture of Compounds 9 and 10) A crude product (2.92 g) was obtained in the same manner as in the preparation of the mixture of Compounds 8a and 8b described above, except that 1,5-dihydroxynaphthalene was replaced with 1,6-hydroxynaphthalene. Acetic anhydride (152 mL) was added to this crude product to prepare a solution, which was refluxed at 100°C for 2 days and then cooled to room temperature. The solvent was then distilled off from the reaction mixture under reduced pressure. The resulting residue was purified by silica gel column chromatography (dichloromethane → dichloromethane / 2-butanol = 99:1), yielding a mixture of the acetylated products of Compounds 9 and 10 as an orange powder (560 mg, 15%). 1 H NMR (500MHz, CDCl3) δ(ppm): 8.76(dd, J=8.9Hz, 3.7Hz, 2H), 8.12(d, J=8.3Hz, 0.6H), 7.84(d, J=2.0Hz, 0.3H), 7.61(d, J=2.0Hz, 2H), 7.53-7.49(m, 4H), 7.42-7.36(m, 1H), 7.09(d, J=8.3Hz, 0.3H), 6.92(dd, J=8.6Hz, 2.9Hz, 2H), 6.86(d, J=2.0Hz, 0.6H), 2.39(d, J=9.2Hz, 7H), 2.20(s, 2H). ・ESI-MS (m / z): 575 [M+H] +

[0093] A 1M aqueous sodium hydroxide solution (10 mL) and methanol (10 mL) were added to a mixture of the acetylated compounds of Compound 9 and Compound 10 (560 mg, 0.97 mmol), and the resulting reaction solution was stirred at room temperature for 2 days. Concentrated hydrochloric acid was added to the reaction mixture, and the resulting precipitate was collected by filtration to obtain a mixture of Compound 9 and Compound 10 as a purple powder (388 mg, 89%). 1 H NMR (500MHz, DMSO-d6) δ(ppm): 10.77(s, 0.5H), 10.19 (d, J=19.2Hz, 1H), 8.67-8.63(m, 2H), 7.91(q, J=8.5Hz, 0.7H), 7.46(t, J=9.0Hz, 2H), 7.34(dt, J=9.1Hz, 2.7Hz, 2H), 7.30-7.26(m, 0.3H), 7.20-7.18(m, 2H), 7.14(dd, J=8.3Hz, 2.3Hz, 0.3H), 7.11-7.02(m, 1H), 6.75-6.69(m, 2H), 6.43(d, J=2.0Hz, 0.7H). ・ESI-MS (m / z): 449 [M+H] +

[0094] (Mixture of Compounds 11a and 11b) A crude product was obtained in the same manner as in the preparation of the mixture of Compounds 8a and 8b described above, except that 1,5-dihydroxynaphthalene was replaced with 1,8-dihydroxynaphthalene. This crude product was purified by silica gel column chromatography (dichloromethane / methanol=9:1) to obtain a mixture of Compounds 11a and 11b as a dark green powder (15 mg, 15%).・1H NMR (500MHz, DMSO-d6) δ(ppm): 11.32(s, 2H), 7.91(d, J=8.6Hz, 0.7H), 7.64-7.61(m, 2H), 7.52(td, J=7.8Hz, 3.2Hz, 2H), 7.44-7.42(m, 2H), 7.31(t, J=1.4Hz, 0.4H), 7.16(d, J=1.7Hz, 0.7H), 7.11-7.08(m, 3H), 6.79(dd, J=8.7Hz, 6.4Hz, 2H), 6.52(d, J=2.0Hz, 0.7H). ・ESI-MS (m / z): 449 [M+H] +

[0095] (Mixture of Compounds 12a and 12b) A crude product was obtained in the same manner as in the preparation of the mixture of Compounds 8a and 8b described above, except that 1,5-dihydroxynaphthalene was replaced with 2,7-dihydroxynaphthalene. This crude product was purified by silica gel column chromatography (dichloromethane / methanol=9:1) to obtain a mixture of Compounds 12a and 12b as a red powder (30 mg, 30%).

[0096] [Synthesis 3]

[0097]

[0098] (Mixture of Compound 13 and Compound 14) Sodium hydroxide (22 g, 0.55 mol) and water (22 mL) were added to a mixture of Compound 3 and Compound 4 (3.54 g, 10.2 mmol), and the resulting reaction solution was refluxed at 80° C. for 3 days. The reaction mixture was cooled to room temperature, then mixed with ice (30 g), and then mixed with concentrated hydrochloric acid to produce a precipitate. This precipitate was collected by filtration, and a mixture of Compound 13 and Compound 14 was obtained as a brown powder (1.54 g, 55%).1 H NMR (500MHz, DMSO-d6) δ(ppm): 12.39(s, 0.3H), 12.21(s, 0.7H), 10.68-10.62(m, 1.7H), 10.28(s, 0.3H), 7.85(d, J=8.6Hz, 0.7H), 7.30(s, 0.3H), 7.23(d, J=8.3Hz, 0.3H), 7.04-6.90(m, 2H), 6.67(d, J=2.6Hz, 0.6H), 6.30-6.25(m, 2H). ・ESI-MS (m / z) : 273 [MH] - , 297 [M+Na] +

[0099] [Synthesis 4]

[0100]

[0101] (Mixture of Compound 15a and Compound 15b) 1,3-dihydroxynaphthalene (81.0 mg, 0.51 mmol) and methanesulfonic acid (3 mL) were added to a mixture of Compound 13 and Compound 14 (91.3 mg, 0.33 mmol), and the resulting reaction solution was stirred at 80°C for 1 day. The reaction mixture was cooled to room temperature, then mixed with ice (30 g) and stirred to produce a precipitate. This precipitate was collected by filtration to obtain a crude product. This crude product was purified by silica gel column chromatography (dichloromethane / methanol = 9:1), and a mixture of Compound 15a and Compound 15b was obtained as an orange powder (33.4 mg, 26%). 1 H NMR (500MHz, DMSO-d6) δ(ppm): 11.12(s, 1H), 10.72(s, 1H), 10.11(s, 1H), 8.17(d, J=8.0Hz, 1H), 7.92(d, J=7.7Hz, 1H), 7.31-7.21(m, 2H), 7.01(dd, J=19.0Hz, 8.4Hz, 2H), 6.80(s, 1H), 6.66-6.52(m, 3H), 6.33(s, 1H). ・ESI-MS (m / z): 397 [MH] - , 399 [M+H]+, 421 [M+Na] +

[0102] (Mixture of Compounds 16a and 16b) A crude product was obtained in the same manner as in the preparation of the mixture of Compounds 15a and 15b described above, except that 1,3-dihydroxynaphthalene was replaced with 1,5-dihydroxynaphthalene. This crude product was purified by silica gel column chromatography (dichloromethane / methanol = 9:1 → dichloromethane / methanol = 4:1) to obtain a mixture of Compounds 16a and 16b as a dark purple powder (47.9 mg, 36%). 1 H NMR (500MHz, DMSO-d6) δ(ppm): 10.78(s, 1H), 10.38(d, J=8.3Hz, 1H), 10.20(d, J=9.2 Hz, 1H), 7.94(d, J=8.3Hz, 1H), 7.86-7.78(m, 2H), 7.50(td, J=8.0Hz, 3.7Hz, 1H), 7.25(d, J=2.3Hz, 0.3H), 7.15(dd, J=8.4Hz, 2.4Hz, 0.3H), 7.07-7.02(m, 2H), 6.90(dd, J=3.6Hz, 2.4Hz, 1H), 6.71-6.68(m, 2H), 6.63(td, J=8.9, 2.3Hz, 1H), 6.41(d, J=2.0Hz, 0.7H). ・ESI-MS (m / z): 397 [MH] - , 399 [M+H]+, 421 [M+Na] +

[0103] (Mixture of Compounds 17 and 18) A mixture of Compounds 17 and 18 was obtained as a red powder (543 mg, quant.) in the same manner as in the preparation of the mixture of Compounds 15a and 15b described above, except that 1,3-dihydroxynaphthalene was replaced with 1,6-dihydroxynaphthalene. 1H-NMR (500MHz, DMSO-d6) δ(ppm): 8.36(d, J=9.2Hz, 1H), 7.83(d, J=8.6Hz, 0.3H), 7.38(t, J=7.7Hz, 1H), 7.26(d, J=8.0Hz, 1.7H), 7.16(d,・ESI-MS (m / z): 397 [MH] - , 399 [M+H] +

[0104] (Mixture of Compounds 19a and 19b) A mixture of Compounds 19a and 19b was obtained as a dark purple powder (12.2 mg, 9%) in the same manner as in the preparation of the mixture of Compounds 15a and 15b described above, except that 1,3-dihydroxynaphthalene was replaced with 1,7-dihydroxynaphthalene. 1 H NMR (500MHz, DMSO-d6) δ(ppm): 7.85-7.78(m, 1.6H), 7.73(d, J=2.6Hz, 1H), 7.48(t, J=9.2Hz, 1H), 7.25-7.20(m, 1H), 7.15(dd, J=8.3Hz,・ESI-MS (m / z) : 397 [MH] - , 399 [M+H] +

[0105]

[0106] (Mixture of Compounds 20a and 20b) A mixture of Compounds 20a and 20b was obtained as a purple powder (73.3 mg, 56%) in the same manner as in the preparation of the mixture of Compounds 15a and 15b described above, except that 1,3-dihydroxynaphthalene was replaced with 1,8-dihydroxynaphthalene. 1H NMR (500MHz, DMSO-d6) δ(ppm): 10.79(s, 0.6H), 10.39(s, 0.3H), 10.13(d, J=8.6Hz, 1H), 9.91(d, J=7.4Hz, 1H), 7.84(d, J=8.3Hz, 0.6H), 7.49-7.41(m, 2H), 7.33-7.31(m, 1H), 7.24(d, J=2.3Hz, 0.3H), 7.16(dd, J=8.4Hz, 2.4Hz, 0.3H), 7.07-7.00(m, 2H), 6.84(d, J=2.3Hz, 1H), 6.69-6.60(m, 3H), 6.42(d, J=2.0Hz, 0.7H) ・ESI-MS (m / z): 397 [MH] - , 399 [M+H]+, 421 [M+Na] +

[0107] (Mixture of Compounds 21a and 21b) A mixture of Compounds 21a and 21b was obtained as a red powder (11.8 mg, 9%) in the same manner as in the preparation of the mixture of Compounds 15a and 15b described above, except that 1,3-dihydroxynaphthalene was replaced with 2,3-dihydroxynaphthalene. 1 H NMR (500MHz, DMSO-d6) δ(ppm): 10.74(s, 0.7H), 10.40(s, 0.3H), 10.30(d, J=12.3Hz, 1H), 10.14(d, J=10.9Hz, 1H), 7.94(d, J=8.3Hz, 0.8H), 7.73-7.70(m, 1H), 7.42(d, J=4.9Hz, 1H), 7.35(d, J=2.3Hz, 0.3H), 7.27-7.22(m, 1H), 7.08-6.95(m, 3H), 6.89(d, J=8.6Hz, 0.3H), 6.76(t, J=2.6Hz, 1H), 6.62-6.52(m, 2H), 6.35(d, J=2.0Hz, 0.8H). ・ESI-MS (m / z): 397 [MH] -

[0108] (Mixture of Compounds 22a and 22b) A mixture of Compounds 22a and 22b was obtained as a red powder (43.5 mg, 33%) in the same manner as in the preparation of the mixture of Compounds 15a and 15b described above, except that 1,3-dihydroxynaphthalene was changed to 2,6-dihydroxynaphthalene.

[0109] (Mixture of Compounds 23a and 23b) A mixture of Compounds 23a and 23b was obtained as a red powder (43.5 mg, 33%) in the same manner as in the preparation of the mixture of Compounds 15a and 15b described above, except that 1,3-dihydroxynaphthalene was replaced with 2,7-dihydroxynaphthalene. 1 H NMR (500MHz, DMSO-d6) δ(ppm): 10.79(s, 0.4H), 10.69(s, 0.3H), 10.37(d, J=24.1Hz, 0.2H), 10.15-10.09(m, 1H), 9.99(d, J=4.6Hz, 0.5H), 9.80(d, J=4.9Hz, 0.5H), 7.95-7.91(m, 1H), 7.85(d, J=8.6Hz, 0.4H), 7.77-7.67(m, 1H), 7.61(d, J=3.7Hz, 0.5H), 7.36-7.34(m, 1H), 7.26-7.24(m, 0.5H), 7.14-7.01(m, 1.5H), 6.96-6.91(m, 1H), 6.70(t, J=2.3Hz, 0.5H), 6.66-6.63(m, 1H), 6.61-6.52(m, 1H), 6.48-6.47(m, 0.5H), 6.36(d, J=2.0Hz, 0.3H), 6.30(d, J=2.0Hz, 0.4H). ESI-MS (m / z): 397 [MH] - , 399 [M+H]+ , 421 [M+Na] +

[0110] [Synthesis 5]

[0111]

[0112] (Mixture of Compounds 24a and 24b) 1,6-dihydroxynaphthalene (956 mg, 5.97 mmol) and methanesulfonic acid (8 mL) were added to a mixture of Compounds 13 and 14 (1.1 g, 4.0 mmol), and the resulting reaction solution was stirred at 80°C for 1 day. The reaction mixture was cooled to room temperature, mixed with ice (40 g), and stirred to form a precipitate. This precipitate was collected by filtration to obtain a crude product of a mixture of Compounds 17 and 18. Acetic anhydride (50 mL) was added to this crude product, and the resulting reaction solution was refluxed at 120°C for 3 days. The reaction mixture was cooled to room temperature, and the solvent was removed from the reaction mixture under reduced pressure to obtain a crude product. This crude product was purified by silica gel column chromatography (dichloromethane), and a mixture of Compounds 24a and 24b was obtained as an orange powder (720 mg, 34%). 1 H NMR (500MHz, CDCl3) δ(ppm): 8.54(dd, J=9.2Hz, 3.4Hz, 1H), 8.07(d, J=8.3Hz, 0.4H), 7.80(d, J=2.3Hz, 0.6H), 7.56(t, J=1.8Hz, 1H), 7.45(dd, J=8.6Hz, 2.0Hz, 1H), 7.42-7.37(m, 2H), 7.31(t, J=1.7Hz, 1H), 7.13(d, J=8.3Hz, 0.6H), 7.09(d, J=2.0Hz, 0.2H), 6.95(dd, J=8.6Hz, 2.6Hz, 1H), 6.89-6.82(m, 2.5H), 2.35(d, J=14.0Hz, 8H), 2.22(s, 1H). ・ESI-MS (m / z): 523 [MH] - , 525 [M+H]+, 547 [M+Na] +

[0113] (Mixture of Compounds 17 and 18) To a mixture of Compounds 24a and 24b (690 mg, 1.32 mmol), 1 M sodium hydroxide (12.5 mL) and methanol (13 mL) were added, and the resulting reaction mixture was stirred at room temperature for 1 day. The solvent was then removed from the reaction mixture under reduced pressure. Concentrated hydrochloric acid was added to the resulting residue, and the resulting precipitate was collected by filtration to obtain a mixture of Compounds 17 and 18 as a red powder (543 mg, quant.).

[0114] (Compounds 25 and 26) Pivalic anhydride (2.155 mL) was added to a mixture of Compounds 17 and 18 (503.0 mg, 1.26 mmol), and the resulting reaction solution was stirred at 90°C for three days. The reaction mixture was cooled to room temperature, and the solvent was removed from the reaction mixture under reduced pressure to obtain a crude product. This crude product was purified by silica gel column chromatography (dichloromethane) to obtain Compound 25 as a yellow powder (138.08 mg, 17%) and Compound 26 as a yellow powder (67.6 mg, 8%), respectively. Compound 25: 1 H NMR (500MHz, DMSO-d6) δ(ppm): 8.36(d, J=9.2Hz, 1H), 7.37(d, J=8.9Hz, 1H), 7.30-7.26(m, 2H), 7.19-7.14(m, 2H), 7.04(d, J=8.3Hz, 1H), 6.94(s, 1H), 6.66(dd, J=20.6Hz, 8.6Hz, 3H) ・ESI-MS (m / z): 651 [M+H] + Compound 26: ・ 1 H NMR (400MHz, DMSO-d6) δ(ppm): 8.54-8.65(1H), 8.08-8.19(1H), 7.72-7.82(1H), 7.64-7.73(1H), 7.41-7.60(3H), 7.23-7.29(1H), 6.95-7.05(2H), 6.87-6.95(1H), 1.29-1.39(21H), 1.15-1.24(9H), 1.06-1.09(1H) ・ESI-MS (m / z) : 651 [M+H] +

[0115]

[0116] (Compound 17) Potassium hydroxide (500 mg) and ethanol (10 mL) were added to compound 25 (80.46 mg, 12.4 mmol), and the resulting reaction solution was stirred at room temperature for 2 days. The resulting precipitate was collected by filtration to obtain compound 17 as a red powder (43.8 mg, 89%). 1H NMR (500MHz, DMSO-d6) δ(ppm): 8.34(t, J=9.3Hz, 1H), 7.81(d, J=8.3Hz, 1H), 7.37(d, J=8.6Hz, 1H), 7.28(d, J=8.6Hz, 1H), 7.17(s, 1H), 7.09(d, J=8.0Hz, 1H), 6.95(s, 1H), 6.65(q, J=8.8Hz, 3H), 6.48(s, 1H)

[0117] (Compound 18) Compound 18 was obtained as a red powder (120 mg, 61.1%) in the same manner as in the preparation of Compound 17, except that Compound 25 was changed to Compound 26. 1 H NMR (500MHz, DMSO-d6) δ(ppm): 8.36(d, J=9.2Hz, 1H), 7.37(d, J=8.9Hz, 1H), 7.30-7.26(m, 2H), 7.19-7.14(m, 2H), 7.04(d, J=8.3Hz, 1H), 6.94(s, 1H), 6.66(dd, J=20.6Hz, 8.6Hz, 3H)

[0118] [Synthesis 6]

[0119]

[0120] (Mixture of Compound 27a and Compound 27b) Resorcinol (2.0 g, 18.16 mmol) and methanesulfonic acid (30 mL) were added to 4-hydroxybenzofuran-1,3-dione (1.5 g, 9.14 mmol), and the resulting reaction solution was stirred at 80°C for 1 day. The reaction mixture was cooled to room temperature, mixed with ice (100 g), and stirred to produce a precipitate. This precipitate was collected by filtration and then dissolved in ethanol (60 mL). The resulting solution was recrystallized by adding water (120 mL) little by little to the solution while heating it at 80°C, yielding a mixture of Compound 27a and Compound 27b as a reddish-brown powder (2.8 g, 88%). 1H-NMR (500MHz, DMSO-D6) δ(ppm): 7.48-7.52(1H), 7.38-7.40(0.6H), 7.09-7.11(0.6H), 6.97-6.99(0.4H), 6.49-6.65(6.4H)・ESI-MS(m / z):347 [MH] -

[0121] (Mixture of Compound 28a and Compound 28b) A solution prepared by adding acetic anhydride (20 mL) and N,N-dimethylformaldehyde (20 mL) to a mixture of Compound 27a and Compound 27b (2.4 g, 6.9 mmol) was refluxed at 80°C. The reaction mixture was cooled to room temperature, and the solvent was distilled off from the reaction mixture under reduced pressure. The resulting residue was mixed with aqueous sodium bicarbonate solution (100 mL), and the product was extracted with ethyl acetate (200 mL). The resulting organic layer was washed sequentially with water (300 mL) and saturated brine (100 mL), and the solvent was distilled off under reduced pressure to obtain a crude product. This crude product was purified by silica gel chromatography (dichloromethane → dichloromethane / acetone = 95:5) to obtain Compound 28a as a white powder (263 mg, 8%) and Compound 28b as a white powder (453 mg, 14%). Compound 28a: 1 H-NMR (500MHz, DMSO-D6) δ(ppm): 7.85(t, J=7.8Hz, 1H), 7.47(d, J=7.7Hz, 1H), 7.29-7.31(m, 3H), 6.99(dd, J=2.3Hz, 8.8Hz, 2H), 6.88(d, J=8.6Hz, 2H) ・ESI-MS (m / z): 473 [MH] - Compound 28b: ・ 1 H-NMR (500MHz, DMSO-D6) δ(ppm): 7.97(dd, J=0.9Hz, 7.7Hz, 1H), 7.78(t, J=8.0Hz, 1H), 7.53(dd, J=0.8Hz, 8.0Hz, 1H), 7.27(d, J=2.2Hz, 2H), 7.03(d, 8.6Hz, 2H), 6.93(dd, J=2.3Hz, 8.6Hz, 2H) ・ESI-MS (m / z): 473 [MH] -

[0122] <Evaluation of Fluorescence Properties> The fluorescence properties of each of the above compounds were evaluated using a spectrofluorometer. The pH was measured at 25°C using a pH meter. [Measurement of Fluorescence Intensity] Phosphate buffer solutions were prepared so that the total concentration of Compound 3 and Compound 4 was 1.0 μM and the pH was X (X is an integer from 1 to 14). The fluorescence intensity at an excitation wavelength of 490 nm was measured for each of the prepared phosphate buffer solutions to observe the relationship between pH and fluorescence intensity. The results are shown in Figure 1(a). Figure 1(a) shows that the fluorescence intensity of the phosphate buffer solution is maximized at pH = 8. Figure 1(b) also shows the excitation spectrum and fluorescence spectrum measured using a phosphate buffer solution with a pH of 8. In Figure 1(b), the excitation spectrum was obtained by measuring the fluorescence intensity with the wavelength of the detection light fixed at 510 nm. In Figure 1(b), the fluorescence spectrum was obtained by measuring the fluorescence intensity with the wavelength of the excitation light fixed at 490 nm.

[0123] Phosphate buffer solutions were prepared so that the total concentration of compound 7a and compound 7b was 1.0 μM and the pH was X (X is an integer between 1 and 14). The fluorescence intensity at an excitation wavelength of 532 nm was measured for each prepared phosphate buffer solution to observe the relationship between pH and fluorescence intensity. The results are shown in FIG. 2(a). It can be seen from FIG. 2(a) that the fluorescence intensity of the phosphate buffer solution is maximized at pH = 8. Furthermore, FIG. 2(b) shows the excitation spectrum and fluorescence spectrum measured using a phosphate buffer solution with a pH = 8. In FIG. 2(b), the excitation spectrum was obtained by measuring the fluorescence intensity with the wavelength of the detection light fixed at 560 nm. In FIG. 2(b), the fluorescence spectrum was obtained by measuring the fluorescence intensity with the wavelength of the excitation light fixed at 532 nm.

[0124] Phosphate buffer solutions were prepared so that the total concentration of compound 8a and compound 8b was 1.0 μM and the pH was X (X is an integer from 1 to 14). The fluorescence intensity at an excitation wavelength of 420 nm was measured for each prepared phosphate buffer solution to observe the relationship between pH and fluorescence intensity. The results are shown in FIG. 3(a). It can be seen from FIG. 3(a) that the fluorescence intensity of the phosphate buffer solution is maximized at pH = 5. Furthermore, FIG. 3(b) shows the excitation spectrum and fluorescence spectrum measured using a phosphate buffer solution at pH = 5. In FIG. 3(b), the excitation spectrum was obtained by measuring the fluorescence intensity with the wavelength of detection light fixed at 515 nm. In FIG. 3(b), the fluorescence spectrum was obtained by measuring the fluorescence intensity with the wavelength of excitation light fixed at 420 nm.

[0125] Phosphate buffer solutions were prepared so that the total concentration of compound 9 and compound 10 was 1.0 μM and the pH was X (X is an integer between 1 and 14). The fluorescence intensity at an excitation wavelength of 595 nm was measured for each prepared phosphate buffer solution to observe the relationship between pH and fluorescence intensity. The results are shown in FIG. 4(a). It can be seen from FIG. 4(a) that the fluorescence intensity of the phosphate buffer solution is maximized at pH = 9. Furthermore, FIG. 4(b) shows the excitation spectrum and fluorescence spectrum measured using a phosphate buffer solution with a pH = 9. In FIG. 4(b), the excitation spectrum was obtained by measuring the fluorescence intensity with the wavelength of the detection light fixed at 660 nm. In FIG. 4(b), the fluorescence spectrum was obtained by measuring the fluorescence intensity with the wavelength of the excitation light fixed at 595 nm.

[0126] Phosphate buffer solutions were prepared so that the total concentration of compound 11a and compound 11b was 1.0 μM and the pH was X (X is an integer from 1 to 14). The fluorescence intensity at an excitation wavelength of 470 nm was measured for each prepared phosphate buffer solution to observe the relationship between pH and fluorescence intensity. The results are shown in FIG. 5( a). It can be seen from FIG. 5( a) that the fluorescence intensity of the phosphate buffer solution is maximized at pH = 9. Furthermore, FIG. 5( b) shows the excitation spectrum and fluorescence spectrum measured using a phosphate buffer solution with a pH = 9. In FIG. 5( b), the excitation spectrum was obtained by measuring the fluorescence intensity with the wavelength of detection light fixed at 535 nm. In FIG. 5( b), the fluorescence spectrum was obtained by measuring the fluorescence intensity with the wavelength of excitation light fixed at 470 nm.

[0127] Phosphate buffer solutions were prepared so that the total concentration of compound 15a and compound 15b was 1.0 μM and the pH was X (X is an integer between 1 and 14). The fluorescence intensity at an excitation wavelength of 505 nm was measured for each prepared phosphate buffer solution to observe the relationship between pH and fluorescence intensity. The results are shown in FIG. 6( a). It can be seen from FIG. 6( a) that the fluorescence intensity of the phosphate buffer solution is maximized at pH = 8. Furthermore, FIG. 6( b) shows the excitation spectrum and fluorescence spectrum measured using a phosphate buffer solution with a pH = 8. In FIG. 6( b), the excitation spectrum was obtained by measuring the fluorescence intensity with the wavelength of the detection light fixed at 540 nm. In FIG. 6( b), the fluorescence spectrum was obtained by measuring the fluorescence intensity with the wavelength of the excitation light fixed at 505 nm.

[0128] Phosphate buffer solutions were prepared so that the total concentration of compound 16a and compound 16b was 1.0 μM and the pH was X (X is an integer between 1 and 14). The fluorescence intensity at an excitation wavelength of 512 nm was measured for each prepared phosphate buffer solution to observe the relationship between pH and fluorescence intensity. The results are shown in FIG. 7( a). It can be seen from FIG. 7( a) that the fluorescence intensity of the phosphate buffer solution is maximized at pH = 7. Furthermore, FIG. 7( b) shows the excitation spectrum and fluorescence spectrum measured using a phosphate buffer solution at pH = 7. In FIG. 7( b), the excitation spectrum was obtained by measuring the fluorescence intensity with the wavelength of detection light fixed at 489 nm. In FIG. 7( b), the fluorescence spectrum was obtained by measuring the fluorescence intensity with the wavelength of excitation light fixed at 512 nm.

[0129] Phosphate buffer solutions were prepared so that the total concentration of compound 17 and compound 18 was 1.0 μM and the pH was X (X is an integer between 1 and 14). For each prepared phosphate buffer solution, the fluorescence intensity at an excitation wavelength of 505 nm and that at an excitation wavelength of 535 nm were measured to observe the relationship between pH and fluorescence intensity. The measurement results of the fluorescence intensity at an excitation wavelength of 505 nm are shown in FIG. 8(a), and the measurement results of the fluorescence intensity at an excitation wavelength of 535 nm are shown in FIG. 9(a). From FIG. 8(a), it can be seen that at an excitation wavelength of 505 nm, the fluorescence intensity of the phosphate buffer solution is maximized at pH = 6. From FIG. 9(a), it can be seen that at an excitation wavelength of 535 nm, the fluorescence intensity of the phosphate buffer solution is maximized at pH = 9. Furthermore, the excitation spectrum and fluorescence spectrum measured using a phosphate buffer solution with a pH of 6 are shown in FIG. 8(b), and the excitation spectrum and fluorescence spectrum measured using a phosphate buffer solution with a pH of 9 are shown in FIG. 9(b). In Figures 8(b) and 9(b), the excitation spectra were obtained by measuring the fluorescence intensity with the wavelength of the detection light fixed at 615 nm, and in Figures 8(b) and 9(b), the fluorescence spectra were obtained by measuring the fluorescence intensity with the wavelength of the excitation light fixed at 535 nm.

[0130] Phosphate buffer solutions were prepared so that the total concentration of compound 19a and compound 19b was 1.0 μM and the pH was X (X is an integer between 1 and 14). The fluorescence intensity at an excitation wavelength of 492 nm was measured for each prepared phosphate buffer solution to observe the relationship between pH and fluorescence intensity. The results are shown in FIG. 10( a). It can be seen from FIG. 10( a) that the fluorescence intensity of the phosphate buffer solution is maximized at pH = 8. Furthermore, FIG. 10( b) shows the excitation spectrum and fluorescence spectrum measured using a phosphate buffer solution with a pH = 8. In FIG. 10( b), the excitation spectrum was obtained by measuring the fluorescence intensity with the wavelength of the detection light fixed at 517 nm. In FIG. 10( b), the fluorescence spectrum was obtained by measuring the fluorescence intensity with the wavelength of the excitation light fixed at 492 nm.

[0131] Phosphate buffer solutions were prepared so that the total concentration of compound 20a and compound 20b was 1.0 μM and the pH was X (X is an integer between 1 and 14). For each prepared phosphate buffer solution, the fluorescence intensity at an excitation wavelength of 490 nm and that at an excitation wavelength of 522 nm were measured to observe the relationship between pH and fluorescence intensity. The measurement results for the fluorescence intensity at an excitation wavelength of 490 nm are shown in FIG. 11(a), and the measurement results for the fluorescence intensity at an excitation wavelength of 522 nm are shown in FIG. 12(a). From FIG. 11(a), it can be seen that at an excitation wavelength of 490 nm, the fluorescence intensity of the phosphate buffer solution is maximized at pH = 7. From FIG. 12(a), it can be seen that at an excitation wavelength of 522 nm, the fluorescence intensity of the phosphate buffer solution is maximized at pH = 7. Furthermore, the excitation spectrum and fluorescence spectrum (shorter wavelength excitation light) measured using a phosphate buffer solution at pH = 7 are shown in FIG. 11(b), and the excitation spectrum and fluorescence spectrum (longer wavelength excitation light) measured using a phosphate buffer solution at pH = 7 are shown in FIG. 12(b). In Fig. 11(b), the excitation spectrum was obtained by measuring the fluorescence intensity with the wavelength of the detection light fixed at 564 nm. In Fig. 11(b), the fluorescence spectrum was obtained by measuring the fluorescence intensity with the wavelength of the excitation light fixed at 490 nm. In Fig. 12(b), the excitation spectrum was obtained by measuring the fluorescence intensity with the wavelength of the detection light fixed at 572 nm. In Fig. 12(b), the fluorescence spectrum was obtained by measuring the fluorescence intensity with the wavelength of the excitation light fixed at 522 nm.

[0132] Phosphate buffer solutions were prepared so that the total concentration of compound 21a and compound 21b was 1.0 μM and the pH was X (X is an integer between 1 and 14). The fluorescence intensity at an excitation wavelength of 493 nm was measured for each prepared phosphate buffer solution to observe the relationship between pH and fluorescence intensity. The results are shown in FIG. 13(a). It can be seen from FIG. 13(a) that the fluorescence intensity of the phosphate buffer solution is maximized at pH = 7. Furthermore, FIG. 13(b) shows the excitation spectrum and fluorescence spectrum measured using a phosphate buffer solution with a pH = 7. In FIG. 13(b), the excitation spectrum was obtained by measuring the fluorescence intensity with the wavelength of the detection light fixed at 518 nm. In FIG. 13(b), the fluorescence spectrum was obtained by measuring the fluorescence intensity with the wavelength of the excitation light fixed at 493 nm.

[0133] Phosphate buffer solutions were prepared so that the total concentration of compound 22a and compound 22b was 1.0 μM and the pH was X (X is an integer between 1 and 14). The fluorescence intensity at an excitation wavelength of 489 nm was measured for each prepared phosphate buffer solution to observe the relationship between pH and fluorescence intensity. The results are shown in FIG. 14(a). It can be seen from FIG. 14(a) that the fluorescence intensity of the phosphate buffer solution is maximized at pH = 8. Furthermore, FIG. 14(b) shows the excitation spectrum and fluorescence spectrum measured using a phosphate buffer solution with a pH = 8. In FIG. 14(b), the excitation spectrum was obtained by measuring the fluorescence intensity with the wavelength of the detection light fixed at 512 nm. In FIG. 14(b), the fluorescence spectrum was obtained by measuring the fluorescence intensity with the wavelength of the excitation light fixed at 489 nm.

[0134] Phosphate buffer solutions were prepared so that the total concentration of compound 23a and compound 23b was 1.0 μM and the pH was X (X is an integer between 1 and 14). The fluorescence intensity at an excitation wavelength of 490 nm was measured for each prepared phosphate buffer solution to observe the relationship between pH and fluorescence intensity. The results are shown in FIG. 15(a). It can be seen from FIG. 15(a) that the fluorescence intensity of the phosphate buffer solution is maximized at pH = 8. Furthermore, FIG. 15(b) shows the excitation spectrum and fluorescence spectrum measured using a phosphate buffer solution with a pH = 8. In FIG. 15(b), the excitation spectrum was obtained by measuring the fluorescence intensity with the wavelength of the detection light fixed at 513 nm. In FIG. 15(b), the fluorescence spectrum was obtained by measuring the fluorescence intensity with the wavelength of the excitation light fixed at 490 nm.

[0135] [Appearance Evaluation] Phosphate buffer solutions were prepared so that the total concentration of Compound 3 and Compound 4 was 10.0 μM and the pH was X (X is an integer from 1 to 14). Each of the prepared phosphate buffer solutions was irradiated with 365 nm excitation light, and the emitted fluorescence was photographed with a camera. The results are shown in FIG.

[0136] Phosphate buffer solutions were prepared so that the total concentration of compound 7a and compound 7b was 50 μM and the pH was X (X is an integer from 1 to 14). Each of the prepared phosphate buffer solutions was irradiated with 365 nm excitation light, and the emitted fluorescence was photographed with a camera. The results are shown in FIG.

[0137] Phosphate buffer solutions were prepared so that the total concentration of compound 8a and compound 8b was 50 μM and the pH was X (X is an integer from 1 to 14). Each of the prepared phosphate buffer solutions was irradiated with 365 nm excitation light, and the emitted fluorescence was photographed with a camera. The results are shown in FIG.

[0138] Phosphate buffer solutions were prepared so that the total concentration of compound 9 and compound 10 was 50 μM and the pH was X (X is an integer from 1 to 14). Each of the prepared phosphate buffer solutions was irradiated with 365 nm excitation light, and the emitted fluorescence was photographed with a camera. The results are shown in FIG.

[0139] Phosphate buffer solutions were prepared so that the total concentration of compound 11a and compound 11b was 50 μM and the pH was X (X is an integer from 1 to 14). Each of the prepared phosphate buffer solutions was irradiated with 365 nm excitation light, and the emitted fluorescence was photographed with a camera. The results are shown in FIG.

[0140] Phosphate buffer solutions were prepared so that the total concentration of compound 15a and compound 15b was 50 μM and the pH was X (X is an integer from 1 to 14). Each of the prepared phosphate buffer solutions was irradiated with 365 nm excitation light, and the emitted fluorescence was photographed with a camera. The results are shown in FIG.

[0141] Phosphate buffer solutions were also prepared so that the total concentration of compound 17 and compound 18 was 50.0 μM and the pH was X (X is an integer from 1 to 14). Each of the prepared phosphate buffer solutions was irradiated with 365 nm excitation light, and the emitted fluorescence was photographed with a camera. The results are shown in FIG.

[0142] 1 to 22 show that the fluorescence intensity of the compounds according to the embodiments of the present disclosure changes depending on the pH. Note that the inventors of the present disclosure have confirmed that the fluorescence intensity and appearance change depending on the pH even for the compounds produced in the above-mentioned section "Synthesis of Compounds" and included in the embodiments of the present disclosure, for which the results of fluorescence intensity measurement and appearance evaluation are not shown.

[0143] [Confocal Laser Fluorescence Microscopy of Stained Cells] HeLa cells were seeded on a 35 mm diameter glass-based dish and incubated in a Dulbecco's modified Eagle's medium containing 10% by volume of fetal bovine serum and 1% by volume of penicillin-streptomycin under 5% CO ２ The cells were cultured at 37°C under a 50°C atmosphere for 1 day. Compound 25 was added to the medium to a final concentration of 5 μM, and the HeLa cells were then cultured for another hour. The medium was removed from the culture, and the HeLa cells were washed with phosphate-buffered saline. The HeLa cells were mixed with phosphate-buffered saline to prepare a cell sample. Green and red fluorescent images of the cell sample were taken using a confocal laser fluorescence microscope. The green fluorescent image is shown in Figure 23(a), the red fluorescent image in Figure 23(b), and a merged image of the green and red fluorescent images in Figure 23(c).

[0144] The merged image of the green and red fluorescent images shows that after being taken up by HeLa cells, non-fluorescent compound 25 is hydrolyzed by hydrolases in the cytoplasm and converted into fluorescent compound 17, which is stained green in a weakly acidic environment, yellow in a neutral environment, and orange in a weakly basic environment. In other words, the compounds of the present disclosure are pH-sensitive, and therefore, by using the compounds of the present disclosure, local pH differences within the cytoplasm can be observed as different color tones.

[0145] According to the present disclosure, it is possible to provide a novel compound having fluorescent properties and pH sensitivity, a derivative of the compound, and a synthetic intermediate of the compound.

Claims

1. A compound represented by the following formula (1): (In the above formula (1), R １ ~R ４ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １ ~R ４ at least one of is a hydroxy group, wavy lines 1 and 2 represent bonding positions with wavy lines 1 and 2 in any of the structures represented by the following formulas (1-1) to (1-4), respectively, and wavy lines 3 and 4 represent bonding positions with wavy lines 3 and 4 in any of the structures represented by the following formulas (1-5) to (1-8), respectively. (In the above formulas (1-1) to (1-4), R １１ ~R １４ , R ２１ ~R ２６ , R ３１ ~R ３６ , and R ４１ ~R ４６ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １１ ~R １４ At least one of R is a hydroxy group; ２１ ~R ２６ At least one of R is a hydroxy group; ３１ ~R ３６ At least one of R is a hydroxy group; ４１ ~R ４６ At least one of the groups is a hydroxy group, and the wavy lines 1 and 2 represent the bonding positions with the wavy lines 1 and 2 in the formula (1), respectively. (In the above formulas (1-5) to (1-8), R ５１ ~R ５４ , R ６１ ~R ６６ , R ７１ ~R ７６ , and R ８１ ~R ８６ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R ５１ ~R ５４ At least one of R is a hydroxy group; ６１ ~R ６６ At least one of R is a hydroxy group; ７１ ~R ７６ At least one of R is a hydroxy group; ８１ ~R ８６ At least one of is a hydroxy group, and wavy lines 3 and 4 represent the bonding positions with wavy lines 3 and 4 in the above formula (1), respectively.

2. The above R １２ is a hydroxy group, and ２２ ~R ２４ At least one of the R ３１ ~R ３４ At least one of the R ４１ , R ４２ and R ４５ At least one of the R ５２ is a hydroxy group, and ６２ ~R ６４ At least one of the R ７１ ~R ７４ At least one of the R ８１ , R ８２ and R ８５ The compound of claim 1 , wherein at least one of is a hydroxy group.

3. The above R １ ~R ４ The compound of claim 1 , wherein at least one of 4. The compound according to claim 1, wherein the structures represented by the formulas (1-1) to (1-4) are structures represented by the following formulas (1-1-1) to (1-4-3):

5. The compound according to claim 1, wherein the structures represented by the formulas (1-5) to (1-8) are structures represented by the following formulas (1-5-1) to (1-8-3):

6. The compound according to claim 1, represented by the following formula (4): (In the above formula (4), R １ ~R ４ are R in the above formula (1), respectively. １ ~R ４ is synonymous with R １１ ~R １４ are R in the above formula (1-1), respectively. １１ ~R １４ is synonymous with R ７１ , R ７２ , and R ７４ ~R ７６ are R in the above formula (1-7), respectively. ７１ , R ７２ , and R ７４ ~R ７６ is synonymous with 7. A compound according to any one of claims 1 to 6, which is a pH indicator.

8. A compound represented by the following formula (3): (In the above formula (3), R １ａ ~R ４ａ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 1 to 10 carbon atoms which may have a substituent, or -OR ｍ１ and —CH 3 contained in the alkyl group or aryl group. ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, ｍ１ represents an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １ａ ~R ４ａ At least one of the ｍ１ The wavy lines 1a and 2a represent bonding positions with the wavy lines 1a and 2a in any of the structures represented by the following formulas (3-1) to (3-4), respectively. The wavy lines 3a and 4a represent bonding positions with the wavy lines 3a and 4a in any of the structures represented by the following formulas (3-5) to (3-8), respectively. (In the above formulas (3-1) to (3-4), R １１ａ ~R １４ａ , R ２１ａ ~R ２６ａ , R ３１ａ ~R ３６ａ , and R ４１ ~R ４６ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 1 to 10 carbon atoms which may have a substituent, or -OR ｍ２ and —CH in the alkyl group or aryl group. ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １１ａ ~R １４ａ At least one of the ｍ２ and R ２２ａ ~R ２６ａ At least one of the ｍ２ and R ３１ａ ~R ３６ａ At least one of the ｍ２ and R ４１ａ ~R ４６ａ At least one of the ｍ２ The wavy lines 1a and 2a represent the bonding positions with the wavy lines 1a and 2a in the above formula (3), respectively. (In the above formulas (3-5) to (3-8), R ５１ａ ~R ５４ａ , R ６１ａ ~R ６６ａ , R ７１ａ ~R ７６ａ , and R ８１ａ ~R ８６ａ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, an aryl group having 1 to 10 carbon atoms which may have a substituent, or -OR ｍ３ and —CH in the alkyl group or aryl group. ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R ５１ａ ~R ５４ａ At least one of the ｍ３ and R ６１ａ ~R ６６ａ At least one of the ｍ３ and R ７１ａ ~R ７６ａ At least one of the ｍ３ and R ８１ａ ~R ８６ａ At least one of the ｍ３ The wavy lines 3a and 4a represent the bonding positions with the wavy lines 3a and 4a in the formula (3), respectively.

9. A compound represented by the following formula (2): (In the above formula (2), R １ｂ ~R ４ｂ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １ｂ ~R ４ｂ At least one of is a hydroxy group, and the wavy line 5 represents the bonding position with the wavy line 5 in any of the structures represented by the following formulas (2-1) to (2-3). (In the above formulas (2-1) to (2-3), R １１ｂ ~R １４ｂ , R ２１ｂ ~R ２６ｂ , and R ３１ｂ ~R ３６ｂ are each independently a hydrogen atom, a halogen atom, a hydroxy group, a cyano group, a carboxy group, an amino group, a thiol group, an alkyl group having 1 to 10 carbon atoms which may have a substituent, or an aryl group having 1 to 10 carbon atoms which may have a substituent, and —CH ２ - may be replaced by -C=C-, -C≡C-, -O-, -OCO-, or -COO-, R １１ｂ ~R １４ｂ At least one of R is a hydroxy group; ２１ｂ ~R ２６ｂ At least one of R is a hydroxy group; ３１ｂ ~R ３６ｂ At least one of is a hydroxy group, and the wavy line 5 represents the bonding position with the wavy line 5 in the above formula (2).

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