JP6489579B2 - Phosphophthalocyanine complex, its salt and its hydrate - Google Patents

Description

  The present invention relates to a phosphorus phthalocyanine complex, and in particular, a phosphorus phthalocyanine complex having a central element of phosphorus, an oxo group (═O) and a hydroxyl group (—OH) as an axial ligand, and further having a sulfo group, It relates to its salts and their hydrates.

  In Japan, where the aging population is advancing, cancer disease control is an indispensable and urgent issue. In cancer disease countermeasures, first, it is necessary to accurately detect a minute cancer tissue. One method for accurately detecting minute cancer tissues is PET (positron emission tomography). However, the PET method requires a large-scale device / facility such as an accelerator, takes time and cost for detection, and causes many restrictions on the use in the medical field.

  Thus, cancer tissue detection methods that do not require large-scale facilities have been studied, for example, photodynamic diagnosis (PDD: Photodynamic Diagnosys). PDD is a diagnostic method in which a photosensitive substance (organic dye or the like) accumulated in a cancer tissue is excited with light such as a laser and the fluorescence is monitored. Photosensitive materials used in PDD include inorganic quantum dots and organic dyes. Many inorganic quantum dots contain elements harmful to the living body such as cadmium, lead, and selenium, and therefore organic dyes are the mainstream of development.

  Among organic dyes, dyes that exhibit light absorption / emission in the wavelength region (visible to near-infrared light region: wavelength 650 to 900 nm) of a “biological light window” are particularly promising. This is because light on the shorter wavelength side than 650 nm is strongly absorbed by biological substances such as muscle / cortex, blood (deoxy- and oxy-hemoglobin), melanin, and cytochrome, and light on the longer wavelength side than 900 nm is water or lipid. This is because it is absorbed by overtone vibrations such as H. Kobayashi, et al. Chem. Rev., 110 (2010) 2620-2640.

  There is a phthalocyanine dye as a dye exhibiting light absorption / emission in the wavelength region of the “biological light window (visible to near infrared light region (wavelength: 650 to 900 nm))”. Since the phthalocyanine dye is specifically accumulated in cancer cells, the position of the cancer can be specified by fluorescence from the dye. Furthermore, it is known that a dye in an excited state generates active oxygen to kill cancer cells, and is used for photodynamic therapy (PDT).

  However, since phthalocyanine dyes are hardly soluble in common organic solvents as well as water, there is a problem that they are difficult to apply to living bodies. Furthermore, there is a problem that not only fluorescence is not seen in the light window of the living body but also active oxygen is not generated due to the interaction between the molecules.

As a water-soluble phthalocyanine dye, IRDye700DX NHS ester (the central element is silicon; absorption maximum 689 nm in aqueous solution, molar extinction coefficient (ε); 170,000 M ⁻¹ cm ⁻¹ ; fluorescence maximum 700 nm, quantum yield (φ) 14% (Non-Patent Document 1)) has been put into practical use. However, the fluorescence quantum yield is as low as 10%, and the synthesis is difficult.

  Moreover, in order to improve water solubility, it is known to substitute the hydrogen atom of the benzene ring outside the phthalocyanine skeleton with a hydrophilic group (Non-patent Document 2). Furthermore, it is also known to add an additive such as a surfactant or alcohol in order to suppress molecular association (Non-patent Document 3, Patent Documents 1 and 2).

Furthermore, an antimony complex of phthalocyanine is known in which the benzene ring of the phthalocyanine skeleton is substituted with a sulfophenoxy group and has an OH group as an axial ligand (Non-patent Documents 4 and 3). The antimony complex has a light absorption maximum wavelength at 730 nm, dissolves in water at a relatively high concentration ( ^{−10 −4} M), and does not associate. However, antimony is toxic, and due to its heavy atom effect, there is a problem that the fluorescence quantum yield is remarkably low, less than 1%, and is not suitable for a fluorescent dye.

  As a phthalocyanine complex that is harmless to a living body, a phosphorus (V) phthalocyanine complex is known. ) (OH) (O)]) (non-patent document 5).

International Publication No. 2010/098359 U.S. Pat. No. 5,524,890 Japanese Patent No. 5586010

L.A.Lavis and R.T.Raines, ACS Chem.Biol., 3 (2008) 142-155 F.Dumoulin, Coord.Chem.Rev., 254 (2010) 2792-2847 H. Isago, et al., J. Inorg. Biochem., 111 (2012) 91-98 H. Isago, et al., J. Inorg. Biochem., 117 (2012) 111-117 H. Isago, et al., J. Porphyrins Phthalocyanines, 17 (2013) 763-771

  However, the above [P (tppc) (OH) (O)] is only slightly soluble in water in the presence of a surfactant.

Therefore, when the present inventors introduced a sulfo group in order to increase the water solubility of the [P (tppc) (OH) (O)], surprisingly, not only the water solubility was improved but also the molecular association. Was remarkably suppressed and the fluorescence quantum efficiency was increased by an order of magnitude, and the present invention was completed. That is, the present invention is as follows.
A phosphorus phthalocyanine complex represented by the following formula (1), a salt thereof or a hydrate thereof

In the above formula, R is an aryl group having 6 to 13 carbon atoms substituted with at least one sulfo group,
z is a linking group selected from the group consisting of -O-, -S-, an alkylene group having 1 to 4 carbon atoms and an oxyalkylene group having 1 to 4 carbon atoms;
n is an integer of 0 to 2 independently of each other, provided that the total of n is 2 or more.
The present invention also relates to a photosensitizing agent or photosensitizing agent for photodynamic diagnosis, which comprises the above-described phosphophthalocyanine complex, a salt thereof, or a hydrate thereof.

  The complex, salt or hydrate of the present invention (hereinafter sometimes referred to collectively as “complex etc.”) is safe for living organisms, is soluble in an aqueous solvent, and has strong light absorption and high luminance at 650 to 800 nm. The fluorescence of is shown. The complex or the like is useful as a photosensitive drug for PPD and PDT.

FIGS. 1A to 1C show structural examples of the phosphophthalocyanine complex of the formula (1). The structural example of the ion derived from the phosphorus phthalocyanine complex of this invention is shown. It is a flowchart which shows an example of the manufacturing method of the phosphorus phthalocyanine complex of this invention. It is a secondary ion mass spectrometry (SIMS) spectrum of the phosphorus phthalocyanine complex prepared in the Example. FIG. 5 is a theoretical SIMS spectrum based on an enlarged view near a molecular ion peak and an isotope distribution in the SIMS spectrum of FIG. 4. They are the fluorescence spectrum (solid line: excitation wavelength 600nm), excitation spectrum (dashed line: observation wavelength 730nm), and absorption spectrum (ash solid line) in the aqueous solution of the phosphorus phthalocyanine complex prepared in the Example. It is the change (upper stage) of an absorption spectrum in the aqueous solution of the phosphophthalocyanine complex prepared in the Example, a formic acid solution, or a sodium hydrogencarbonate solution, and a magnetic circular dichroism spectrum (lower stage). Changes in absorption spectrum when adjusting pH with a TRIS (trishydroxymethylaminomethane) buffer solution of an aqueous solution of phosphophthalocyanine complex prepared in Example (a), plotting absorbance at 676 nm at each pH (b) It is. It is the graph (c) which calculated | required pKa of the spectrum change shown to FIGS. 8-1, and the graph (d) which calculated | required the number of the hydrogen ions involved in this change. It is a change of the absorption spectrum at the time of changing pH using the sodium hydrogencarbonate of the phosphorus phthalocyanine complex aqueous solution prepared in the Example. It is the fluorescence spectrum in the lutidine aqueous solution of the phosphine phthalocyanine complex prepared in the Example, an excitation spectrum, and an absorption spectrum. It is the fluorescence spectrum in the sodium hydroxide aqueous solution of the phospho phthalocyanine complex prepared in the Example, an excitation spectrum, and an absorption spectrum. It is a figure which shows the change by the density | concentration of the absorption spectrum in the aqueous solution of the phosphorus phthalocyanine complex prepared in the Example. It is a graph which shows the change of the absorption intensity with respect to the density | concentration in different pH of the phosphorus phthalocyanine complex prepared in the Example. The absorption spectrum in the aqueous solution of the phosphorus phthalocyanine complex prepared in the Example, a metal-free analog, and a copper complex is compared.

(Phosphophthalocyanine complex)
The phosphorus phthalocyanine complex of the present invention (hereinafter sometimes simply referred to as “complex”) is represented by the following formula (1).

In the above formula, R is an aryl group having 6 to 13 carbon atoms substituted with at least one sulfo group (SO ₃ H). z is -O-, -S-, and a linking group selected from the group consisting of an alkylene group having 1 to 4 carbon atoms and an oxyalkylene group having 1 to 4 carbon atoms, and n is an integer of 0 to 2 independently of each other. However, the total of n is 2 or more.

  Examples of the aryl group having 6 to 13 carbon atoms include a phenyl group, an indenyl group, a naphthyl group, and an azulenyl group, and among these, a phenyl group and a naphthyl group are preferable.

Each aryl group is substituted with at least one sulfo group (SO ₃ H). The upper limit of the number of the sulfo group is not particularly limited, but when the aryl group is a phenyl group, it is actually 3 due to synthesis restrictions. Polar groups other than sulfo groups, such as carboxy groups, phosphoryl groups (—P (═O) (OH) ₂ ), amino groups, and the like can also be used for the purpose of improving water solubility, but they are highly polar and synthetically A sulfo group is most preferable in terms of easy control. The sulfo group may exist in the form of a sulfonate (—SO ₃ ⁻ ) in which protons are dissociated in an aqueous medium.

  Each R may have other substituents in addition to the sulfo group. As the substituent, a group that does not make the sulfonation reaction difficult is preferable, for example, an alkyl group having 1 to 4 carbon atoms such as a methyl group or an ethyl group, an alkoxy group having 1 to 4 carbon atoms such as a methoxy group, a cyano group, Examples thereof include halogeno groups such as a nitro group and a fluoro group. Preferably they are a C1-C4 alkyl group and a C1-C4 alkoxy group, More preferably, it is a C1-C2 alkyl group.

  The substitution position of the sulfo group in each R may be arbitrary. In the phosphophthalocyanine complex prepared in the examples described later, it is the para position of the linking group -O-, but this is simply selected for convenience for the structural analysis without the regioisomer, and other substitutions. Even the position has little effect on the phthalocyanine skeleton and does not affect the fluorescence properties.

  z is a linking group selected from the group consisting of -O-, -S-, an alkylene group having 1 to 4 carbon atoms, and an oxyalkylene group having 1 to 4 carbon atoms. Examples of the alkylene group having 1 to 4 carbon atoms include a methylene group and an ethylene group, and examples of the oxyalkylene group having 1 to 4 carbon atoms include an ethyleneoxy group and a propyleneoxy group. Of these, -O- and -S- are preferred.

  Preferable R is at least one sulfo group and a phenyl group substituted with 1 or 2 carbon atoms such as a sulfomethylphenyl group, a sulfodimethylphenyl group, a 4′-sulfo-2 ′, 6′-dimethylphenyl group. Is mentioned.

  The position of R is at least one of the α-position and β-position of the peripheral benzene ring in the phthalocyanine skeleton. The β-position is preferred from the viewpoint of more activating the phthalocyanine axial ligand.

  n is an integer of 0 to 2 independently of each other, provided that the total of n is 2 or more. If n is less than 2, it may be difficult to achieve the desired water solubility. Preferably, the total of n is 3 or more, more preferably 4 or more. For example, each n is all 1. 1A to 1C show structural examples of a phosphorus phthalocyanine complex in which the total of n is 5 or the like in the formula (1). In these figures, “phosphorus” in the compound names is abbreviated.

The complex has an oxo group (═O) and a hydroxyl group (—OH) as an axial ligand, that is, a z-direction ligand when the phthalocyanine skeleton is in the xy direction. These ligands, -O in an aqueous medium is -OH ⁺ or dissociated protonated as described below ^- not only enhance the existing obtained, solubility in water of the complex, the molecular associations It was also found that the effect of decreasing the sex was also achieved.

The present invention also relates to salts of the above complexes. The salt contains an ion derived from the complex and a counter ion, and may further contain water of hydration. The ion derived from the complex includes any one of at least one sulfonate group, an —OH ⁺ group in which a proton is added to the oxo group of the axial ligand, and an —O ⁻ group in which a hydroxyl group is ionized. The structure was confirmed by a magnetic circular dichroism spectrum. This ionization was also confirmed to be a rapid and reversible reaction that occurs by proton transfer. Although the dissociation constant (pKa) of each ionization may vary depending on R, z, etc., in the case of the structure of FIG. 2, it is about 3-5 and 7-9, respectively.

The counter ion is not particularly limited. Counter cations include alkali metal ions such as Na ⁺ , alkaline earth metal ions such as Ca ²⁺ , tetraalkylammonium ions such as ammonium ions and tetramethylammonium ions, hydroxyammonium ions such as trishydroxymethylammonium, N-methyl Examples include pyridinium ions such as pyridinium, picolinium ions, lutidinium ions, and imidazolinium ions such as N, N-dimethylimidazolinium. Cl as counter anion ^- halogen ions such, cyanide, nitrate, bicarbonate ions, carbonate ions, formate ions, and an organic acid ion such as acetate ion.

  Each of the complexes or salts may be a hydrate. The number of water of hydration may vary depending on the degree of drying of the complex or salt, but is usually obtained with a hydrate of about 4-10.

  The structure of the complex of the present invention can be identified by elemental analysis, secondary ion mass spectrometry and NMR.

The complex of the present invention is useful as a photosensitive substance for PDD and PDT. In particular, the form in which the axial ligand is —OH ⁺ or dissociated —O ^— has a remarkably low degree of molecular association and is very useful as a PDT photosensitizer. For example, phosphorus (V) tetra (4′-sulfonic acid-2 ′, 6′-dimethylphenoxy) phthalocyanine (hereinafter referred to as [P (H4tsppc) (O) (OH)]) prepared in the examples described later may be used. In the case of having any of the above-mentioned axial ligands, the absorbance is proportional to the concentration according to the Lambert-Beer rule even at a concentration of 10 ⁻⁴ M. Particularly -O ^- those with the emit strong fluorescence, expressed in fluorescence quantum yield relative to the quantum yield of the THF solution of tetra -t- butyl phthalocyanine, and 46 to 49%, commercially available water-soluble phthalocyanine It is significantly higher than the 14% quantum yield of IRDye700DX NHS ester, which is a dye.
In the present application, the fluorescence quantum yield (φ) is a ratio m / n between the number m of emitted molecules (fluorescence) and the number n of photons absorbed. A quantum yield of 46% means that if there are 100 molecules excited by absorbing light, 46 of them emit fluorescence. The luminance of fluorescence is proportional to the molar extinction coefficient (ε) × fluorescence quantum yield (φ).

(Method for producing phosphophthalocyanine complex)
The complex of the present invention can be prepared, for example, according to the flowchart shown in FIG. The production method can be broadly divided into a sulfonation step and a purification step.

(Solid product preparation step S1)
This is a sulfonation step. As a starting material, for example, phosphorus 2,6-dimethylphenoxyphthalocyanine ([PPc (O) (OH)]) is prepared by the method described in Non-Patent Document 5.

  Next, [PPc (O) (OH)] is sulfonated. The sulfonating agent is not particularly limited, and for example, sulfuric acid such as fuming sulfuric acid and concentrated sulfuric acid, chlorosulfonic acid and the like can be used. A sufficient amount of concentrated sulfuric acid is preferably used to serve as a reaction solvent and to dissolve the starting material. The temperature of sulfonation is 0 ° C. (under ice cooling) to room temperature, preferably 10 ° C. or less. The sulfonation occurs rapidly and appears to be complete while the starting material is dissolved in concentrated sulfuric acid and unreacted material is removed by filtration. The sulfonated product can be obtained in about 5 to 30 minutes, typically 10 minutes or less, including all steps from dissolution of the starting material to filtration.

  After the reaction is complete, the reaction is filtered and the filtrate is collected. The filtration residue solid is discarded. If the starting material is sufficiently purified, little solid remains. The filtrate is dropped into ice water to precipitate a sulfonated product, followed by filtration to obtain a crude sulfonated product.

The resulting crude sulfonated product is purified by the following reprecipitation and separation steps, and finally dried.
(Tar-like product making process S2)
The solid product is dissolved in cold water and then filtered, and the filtrate is collected. An alcohol is added to the filtrate and then concentrated using a rotary evaporator (RE) or the like to obtain a tar-like product.

(Film-like product creation step S3)
The tar-like product is redissolved in alcohol and then concentrated with RE to produce a film-like product.

(Fine solid product creation step S4)
The film-like product is redissolved in alcohol and then dropped into ether to reprecipitate a fine solid product in the mother liquor.

(Centrifuge separation step S5)
Centrifugation step S5 is a step of centrifuging. It includes an initial centrifugation step S5-1, a solution dropping step S5-2, and another centrifugation step S5-3.

(First centrifugation step S5-1)
The fine solid product alcohol / ether dispersion obtained in S4 is centrifuged. A fine solid product is separated from the mother liquor and turns into a tar-like substance.

(Solution dropping step S5-2)
After dissolving the tar-like substance in alcohol, the tar-like substance solution is dropped into ether to produce a fine solid product in the mother liquor.

(Another centrifugation step S5-3)
Centrifuge the fine solid product alcohol / ether solution. When the fine solid product is separated from the mother liquor and changed to a tar-like substance by centrifugation, the solution dropping step S5-2 and another centrifugation step S5-3 are repeated. In the repeating step, it is preferable to change the mixing ratio of alcohol / ether.
If the solid product is separated from the mother liquor by centrifugation and does not change to a tar-like substance and a solid is obtained, the process proceeds to a vacuum drying step S6.

(Vacuum drying step S6)
The solid is vacuum dried to obtain a phosphophthalocyanine complex.

  The salt of the phosphophthalocyanine complex can be prepared by dissolving the complex in an aqueous solvent, adding an acid or base containing a counter ion, and removing the aqueous solvent. As will be described later, the structural change of the complex due to the addition of an acid or base is reversible, and is faster as the diffusion rate of the acid or base becomes rate-limiting.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.
<Synthesis>
According to the method described in Non-Patent Document 5, a phosphorus phthalocyanine complex represented by the following formula [P (tppc) (O) (OH)] · 4H ₂ O (hereinafter referred to as [P (tppc) (O) (OH)] ) Was synthesized.

[P (tppc) (O) (OH)] emitted red fluorescence in an ethanol solution at an excitation wavelength of 532 nm (1 mW). This compound is slightly water-soluble, but even at a concentration of less than 10 ⁻⁶ M, it is significantly associated unless it is in the presence of a surfactant (Non-patent Document 5).

  200 g (0.19 mmol) of [P (tppc) (O) (OH)] was dissolved in 21 ml of ice-cooled concentrated sulfuric acid, sulfonated by stirring for 10 minutes, filtered, and the filtrate obtained. Was dropped into about 17 g of ice to precipitate a green solid sulfonated product.

  It was then filtered to collect a green solid. The collected green solid was then dissolved in 40 ml of cold water and filtered once more. The solid obtained by filtration was discarded. Since the raw material was sufficiently purified, almost no solid remained. Next, 20 ml of ethanol was added to the filtrate, and then concentrated at about 40 ° C. using a rotary evaporator to obtain a tar-like product.

  Next, this tar-like product was dissolved in about 5 ml of ethanol, and then concentrated at 50 ° C. or lower using a rotary evaporator. This operation was repeated to obtain a dry film-like product for the second time.

Next, this dry film-like product was dissolved in 10 ml of methanol and then dropped into about 40 ml of ether to precipitate a fine green solid.
The green fine solid was then centrifuged from the mother liquor. Further, by repeating the dissolution and reprecipitation operations twice with 5 ml of methanol / 45 ml of ether and once with 2 ml of methanol / 48 ml of ether, a green solid was obtained.
The resulting green solid was dried in vacuum at 40 ° C. for 12 hours to obtain the final product phosphorus (V) tetra (4′-sulfonic acid-2 ′, 6′-dimethylphenoxy) phthalocyanine ([P 75 mg (0.048 mmol) of (H4tsppc) (O) (OH)]) was obtained. The yield was 25%.

<Structural analysis>
The structure of the obtained complex was analyzed by secondary ion mass spectrometry (SIMS) and elemental analysis.
[SIMS]
JEOL-JMS-T100LC manufactured by JEOL Ltd. was used. FIG. 4 shows the SIMS spectrum of the complex and the assignment of the main peaks. The molecular ion peak was detected in protonated form (m / z = 1377 [M + H ⁺ ]). FIG. 5 is an enlarged view of the vicinity of the molecular ion peak, and the inset is a theoretical SIMS spectrum based on the isotope distribution. From the very good agreement between FIGS. 4 and 5, the correctness of the attribution was confirmed.
The other main peaks are as follows:
m / z = 1359: [M-OH], in which one axial ligand OH was lost during ionization.
m / z = 1314: [MP (= O) (OH) + 2H], a phthalocyanine having no central element, that is, the central element and the axial ligand lost and two hydrogens added.
A very weak but aprotic molecular ion peak was also detected (m / z = 1376 [M]).

[Elemental analysis]
The results of elemental analysis were as follows: carbon 49.22%; hydrogen 4.11%; nitrogen 7.22%. From this, [P (H4tsppc) (OH) (O)]. 10H ₂ O (C ₆₄ H ₆₉ N ₈ O ₂₈ PS ₄ ) (theoretical value: carbon 49.35%; hydrogen 4.47%; nitrogen 7. 19%).

<Absorption and fluorescence spectra>
The fluorescence and excitation spectrum of the above aqueous solution of [P (H4tsppc) (OH) (O)] · 10H ₂ O were measured using a Hitachi F-2500 fluorescence measuring apparatus. Moreover, the absorption spectrum of aqueous solution was measured using Shimadzu UV-1800 spectrophotometer.
FIG. 6 shows the fluorescence spectrum (solid line: excitation wavelength 600 nm), excitation spectrum (broken line: observation wavelength 730 nm), and absorption spectrum (grey solid line). In the figure, the intensities of the fluorescence spectrum and the excitation spectrum are arbitrary scales and are normalized for comparison with the absorption spectrum.
From the figure, it can be seen that [P (H4tsppc) (OH) (O)] · 10H ₂ O exhibits strong absorption in the wavelength region of the “biological light window” and high-intensity fluorescence based on the absorption.
The fluorescence quantum yield based on the quantum yield of the THF solution of tetra-t-butylphthalocyanine was 0.326 (about 33%) (for details of the method, see N. Kobayashi, Chem. Lett., (1994 )
(See 1813-1816).
The molar absorption coefficient of the absorption band having a maximum at 692 nm was 160,000 M ⁻¹ cm ⁻¹ .
The above-mentioned fluorescence quantum yield is a commercially available water-soluble phthalocyanine dye, IRDye700DX NHS ester (the central element is silicon; absorption maximum 689 nm in aqueous solution, molar extinction coefficient: 170,000 M ⁻¹ cm ⁻¹ ; fluorescence maximum 700 nm, quantum yield Compared with the rate of 14% (Non-patent Document 1), the molar extinction coefficient is almost the same.

<Changes in absorption spectrum due to ion morphology>
As already mentioned, the complexes of the invention ionize rapidly in response to changes in pH in an aqueous medium and exhibit the accompanying spectral changes. FIG. 7 shows [P (H4tsppc) (O) (OH)] in an aqueous solution (2.5 × 10 ⁻⁶ M, solid line), 0.13 M formic acid solution (concentration 8.6 × 10 ⁻⁶ M, broken line) and 24 mM. It is a change of the absorption spectrum (upper part) and the magnetic circular dichroism spectrum (lower part) in the sodium hydrogencarbonate solution (concentration 6.8x10 ^-6 M, one-dot broken line). Absorption maximum shifts short wavelength under weak basicity and long wavelength shift under weak acidity. These absorption maximum wavelengths coincide with the wavelength at which Δε of the magnetic circular dichroism spectrum (difference in absorption coefficient of left and right circularly polarized light) is zero, so [P (H4tsppc) (O) (OH )] The C4 symmetry of the molecule was maintained, and it was confirmed that the structural change due to pH occurred on the axial ligand.

FIG. 8-1 is a graph (b) plotting changes in absorption spectrum (a) when pH is adjusted with TRIS (trishydroxymethylaminomethane) buffer and absorbance at 676 nm at each pH. As the pH increases, the peak becomes sharper and stronger, and the absorption maximum shifts by a shorter wavelength. As shown in the figure (a), since there is an isosbestic point near 680 nm, it was found that an equilibrium reaction occurred.
The sigmoid curve shown in FIG. 8-1 (b) shows the absorbance at 676 nm (A), initial absorbance (A ₀ ), absorbance at the end of pH change (A _f ), and dissociation constant (pKa = 7). .87), and the pKa was obtained from the graph shown in FIG. 8-2 (c). From these results, it was found that one hydrogen ion (n = 1.22 in FIG. 8-2 (d)) is involved in the change of the absorption spectrum in FIG. A similar phenomenon was observed on the acidic side.

  A similar change in absorption spectrum was observed when the pH was changed using sodium bicarbonate instead of TRIS (FIG. 9).

  The change in ion form and spectrum in response to the pH change is very rapid and occurs at the moment when an acid or base containing a counter ion is added. Since the fluorescence is in the near infrared region on the acidic side, it cannot be visually confirmed, and strong red fluorescence can be confirmed on the neutral and basic sides. If this phenomenon is utilized, it can be used as a highly sensitive indicator showing the pH of a physiological environment.

  As described above, the complex of the present invention exhibits strong absorption on the basic side and fluorescence becomes strong. FIG. 10 shows the case where the base is lutidine, and FIG. 11 shows the case where the base is sodium hydroxide. The neutral fluorescence quantum yield was about 33%, compared with 49% in the presence of lutidine and 46% in the presence of sodium hydroxide. From this, an excellent fluorescent dye can be obtained by forming a weakly basic physiological environment by, for example, administering the complex of the present invention into a form of lutidinium salt, sodium salt, or the like together with a base such as sodium hydrogen carbonate. It is expected to be

[Concentration dependence of absorption spectrum]
In order to investigate the presence or absence of molecular association, the concentration dependence of the absorption spectrum intensity of [P (H4tsppc) (O) (OH)] was examined. Even if the association occurs, the linearity of the absorbance according to the Lambert-Beer rule may be maintained, but in general, it can be said that the association occurs when the linearity deviates from the linearity.
FIG. 12 shows the change of the absorption spectrum in water depending on the concentration. Similar experiments were performed at different pHs and the change in absorbance per unit optical path length versus concentration was plotted (FIG. 13).
As can be seen from FIG. 13, in water (◯), it begins to deviate from the straight line after 0.1 × 10 ⁻⁴ M, but in NaOH solution (●) and HCl (Δ), it is good up to 1 × 10 ⁻⁴ M. It was found that the influence of molecular association was negligible up to 1 × 10 ⁻⁴ M at least an order of magnitude higher under neutrality under acidic and basic conditions. Also from here, the complex of the present invention is expected to be an excellent dye for PDT.

<Comparison with existing pigments>
FIG. 14 compares [P (H4tsppc) (O) (OH)] with absorption spectra (Non-patent Document 4) of metal-free analogs and copper complexes in an aqueous solution. The absorption spectrum peak value of [P (H4tsppc) (O) (OH)] was significantly higher than the absorption spectrum peak value in the aqueous solution of the metal-free analog and copper complex. The metal-free analog and copper complex were strongly associated in an aqueous solution in the absence of a surfactant or alcohol.

The phosphophthalocyanine complex of the present invention is useful as a photosensitizer for PDD and PDT, and as a pH indicator.

Claims (8)

A phosphorus phthalocyanine complex represented by the following formula (1), a salt thereof or a hydrate thereof

In the above formula, R is an aryl group having 6 to 13 carbon atoms substituted with at least one sulfo group,
z is a linking group selected from the group consisting of -O-, -S-, an alkylene group having 1 to 4 carbon atoms and an oxyalkylene group having 1 to 4 carbon atoms;
n is an integer of 0 to 2 independently of each other, provided that the total of n is 2 or more.   The R is further substituted with at least one group selected from the group consisting of an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a cyano group, a nitro group, and a halogeno group. 2. The phosphophthalocyanine complex according to 1, a salt thereof or a hydrate thereof.   The phosphophthalocyanine complex, a salt thereof or a hydrate thereof according to claim 1 or 2, wherein R is a phenyl group substituted with at least one sulfo group and an alkyl group having 1 or 2 carbon atoms.   The phosphophthalocyanine complex, a salt thereof or a hydrate thereof according to claim 3, wherein R is a 4'-sulfo-2 ', 6'-dimethylphenyl group.   The phosphorus phthalocyanine complex, its salt or hydrate thereof according to any one of claims 1 to 4, wherein z is -O- or -S-.   The phosphophthalocyanine complex according to any one of claims 1 to 5, wherein all n's are 1.   The photosensitive drug for photodynamic diagnostics containing the phosphophthalocyanine complex of any one of Claims 1-6, its salt, or those hydrates. A pH indicator comprising the phosphophthalocyanine complex according to any one of claims 1 to 6, a salt thereof, or a hydrate thereof.