Luminescent compound, method for producing luminescent compound, luminescent composition, luminescent thin film, and luminescent particle

Abstract

A luminescent compound according to the present invention has a structure represented by general formula (1). (In the formula, R represents a light emitting dye skeleton; X represents an ionic substituent; and L represents a single bond, an oxygen atom, a sulfur atom, a selenium atom or an NH group.)

Description

[Technical field]

[0001] The present invention relates to a luminescent compound, a method for producing a luminescent compound, a luminescent composition, a luminescent thin film, and a luminescent particle, and in particular to a luminescent compound which is highly water-soluble and has excellent luminescence even under high concentration conditions due to a concentration quenching suppression effect. [Background technology]

[0002] Perylene bisimide derivatives are substances whose skeletons have been publicly known since at least 1995. Perylene bisimide derivatives are used as luminescent materials and the like due to their potentially high luminescence quantum yield, high robustness, ease of tuning the luminescence wavelength, and simplicity of synthesis (see, for example, Patent Document 1). However, perylene bisimide derivatives, which are polycyclic aromatic compounds with a large π-conjugated plane, have a π-π * These aromatic compounds exhibit luminescence derived from transitions and show high luminescence quantum yields in dilute solutions. However, when using aromatic compounds, which are inherently highly lipophilic, as water-soluble dyes, problems arise in aggregation due to the hydrophobic effect of the core portion of the dye and the resulting decrease in luminescence due to concentration quenching. As a result, these compounds have the disadvantage of significantly decreasing the luminescence quantum yield in highly concentrated solutions or solids. For example, when phosphor-aggregated nanoparticles are used in immunostaining methods, multiple fluorescent dyes are encapsulated in a small-diameter parent substance or attached to the surface to accumulate, resulting in good luminescence; however, under high-concentration conditions, the interaction between the highly lipid-soluble aromatic moieties of the dyes is particularly strong due to the hydrophobic effect, leading to aggregation and a problem of reduced luminescence due to concentration quenching. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 065502 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention has been made in consideration of the above problems and circumstances, and the problem to be solved by the present invention is to provide a luminescent compound that is highly water-soluble and has excellent luminescence properties even under high concentration conditions due to its concentration quenching suppression effect, and a method for producing the same, and also to provide a luminescent composition, a luminescent thin film, and a luminescent particle that contain the luminescent compound. [Means for solving the problem]

[0005] In the course of investigating the causes of the above problems in order to solve the above problems, the present inventors discovered that by introducing a biphenyloxy group substituted with a water-soluble substituent into each benzene ring of an oil-soluble dye, it is possible to provide a luminescent compound or the like which is highly water-soluble and exhibits a concentration quenching suppression effect even under high concentration conditions, and thus arrived at the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

[0006] 1. A luminescent compound having the following compound 1-1. [ka]

[0013] 2. No. 1 In the section A method for producing a luminescent compound according to the present invention, comprising the steps of: This is a method for producing a luminescent compound by sulfonating a dye molecule having a 2-biphenyloxy group, thereby introducing one sulfo group into each benzene ring. [ka] [In the formula, R represents a luminescent dye skeleton.]

[0014] 3. No. 1 In the section A luminescent composition comprising the luminescent compound described above.

[0015] 4. No. 1 In the section A luminescent thin film containing the luminescent compound described above.

[0016] 5. No. 1 In the section A luminescent particle comprising the luminescent compound described above. Effect of the Invention

[0017] The above-mentioned means of the present invention provide a luminescent compound which is highly water-soluble and has excellent luminescence even under high concentration conditions due to its concentration quenching suppression effect, and a method for producing the same. It is also possible to provide a luminescent composition, a luminescent thin film, and a luminescent particle containing the luminescent compound. Although the mechanism by which the effects of the present invention are manifested or the mechanism by which the effects of the present invention are acted upon has not been clearly understood, it is speculated as follows. In the luminescent compound of the present invention, a biphenyloxy group substituted with an ionic substituent, which is a water-soluble substituent, is introduced to each benzene ring of a fat-soluble dye. The electrostatic repulsion caused by this ionic substituent suppresses the interaction between the fat-soluble dye cores, and the aggregation between molecules can be suppressed. As a result, even under high concentration conditions, it is presumed that the quenching caused by the aggregation is reduced, and the luminescence is improved. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 shows the change in quantum yield when the dye doping concentration is increased in the compound 1-1 of the present invention, the comparative compound 1, and the comparative compound 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The luminescent compound of the present invention has a structure represented by the above general formula (1). This feature is a technical feature common to or corresponding to each of the following embodiments.

[0020] As an embodiment of the present invention, it is preferable that the structure represented by the general formula (1) has a structure represented by the general formula (2) in terms of excellent concentration quenching suppression effect. In the general formula (1), it is preferable that the luminescent dye skeleton represented by R has a structure represented by any one of the mother nuclei shown above, in terms of excellent concentration quenching suppression effect. In the general formula (1), the ionic substituent represented by X is preferably any one of a sulfo group, a phosphoric acid group, a sulfonate group, a phosphoric acid ester group, an ammonium group, or a salt thereof, in terms of excellent concentration quenching suppression effect. In addition, in the general formula (1), it is preferable that L is an oxygen atom and the ionic substituent represented by X is either a sulfo group or a salt thereof, in terms of excellent concentration quenching suppression effect. Furthermore, it is preferable that the luminescent compound having the structure represented by the general formula (1) above also has the structure represented by the general formula (3) above, in terms of excellent concentration quenching suppression effect.

[0021] The method for producing a luminescent compound of the present invention introduces one sulfo group into each benzene ring by sulfonating a dye molecule having a 2-biphenyloxy group, which allows substitution with multiple ionic substituents at once, resulting in excellent production efficiency.

[0022] The luminescent compound of the present invention is suitably used for luminescent compositions, luminescent thin films and luminescent particles.

[0023] The present invention, its components, and embodiments and aspects for carrying out the present invention will be described below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after the symbol "to" are included as lower and upper limits.

[0024] [Luminescent compounds] The light-emitting compound of the present invention has a structure represented by the following general formula (1). [ka] [In the formula, R represents a luminescent dye skeleton, X represents an ionic substituent, and L represents a single bond, an oxygen atom, a sulfur atom, a selenium atom, or an NH group.]

[0025] In the above general formula (1), the luminescent dye skeleton represented by R preferably has a structure represented by any one of the mother nuclei shown below. [ka]

[0026] In the general formula (1), the ionic substituent represented by X is preferably any one of a sulfo group, a phosphoric acid group, a sulfonate group, a phosphoric acid ester group, an ammonium group, a carboxy group, a phosphonium group, or a salt thereof. Among these, a sulfo group, a phosphoric acid group, a sulfonate group, a phosphoric acid ester group, an ammonium group, or a salt thereof is more preferable, and a sulfo group or a salt thereof is particularly preferable. Specifically, -SO 3 H, -SO 3 Na, -OSO 3 H, -OSO 3 Na, -SO 3 NH 4 , -PO 4 H 2 , -PO 4 Na, -OPO 3 H 2 , -OPO 3 Na 2 , -NMe 3 OH, -NMe 3 Cl and the like.

[0027] In the general formula (1), L represents a single bond, an oxygen atom, a sulfur atom, a selenium atom or an NH group, and is particularly preferably an oxygen atom.

[0028] The structure represented by the general formula (1) preferably has a structure represented by the following general formula (2) in terms of excellent concentration quenching suppression effect.

[0029] [ka] [In the formula, R represents a luminescent dye skeleton, X represents an ionic substituent, and L represents a single bond, an oxygen atom, a sulfur atom, a selenium atom, or an NH group.]

[0030] In the general formula (2), R, X, and L are the same as R, X, and L in the general formula (1).

[0031] Moreover, it is preferable that the luminescent compound of the present invention has a structure represented by the following general formula (3) in that it has an excellent effect of suppressing concentration quenching. [ka] [In the formula, X represents a sulfo group or a salt thereof.]

[0032] Specific examples of the luminescent compound having the structure represented by the general formula (1) are shown below, but the invention is not limited thereto.

[0033] [ka]

[0034] [ka]

[0035] [ka]

[0036] [ka]

[0037] [ka]

[0038] [ka]

[0039] [ka]

[0040] [ka]

[0041]

change

[0042]

change

[0043]

change

[0044]

change

[0045]

change

[0046]

change

[0047]

change

[0048]

change

[0049]

change

[0050]

change

[0051]

change

[0052]

change

[0053]

change

[0054]

change

[0055]

change

[0056]

change

[0057]

change

[0058]

change

[0059]

change

[0060]

change

[0061]

change

[0062]

change

[0063]

change

[0064]

change

[0065]

change

[0066]

change

[0067]

change

[0068]

change

[0069]

change

[0070]

change

[0071]

change

[0072] [ka]

[0073] [ka]

[0074] [ka]

[0075] [ka]

[0076] [ka]

[0077] [ka]

[0078] [Method of producing luminescent compound] The method for producing a luminescent compound of the present invention introduces one sulfo group into each benzene ring by sulfonating a dye molecule having a 2-biphenyloxy group, which allows substitution with multiple ionic substituents at once, resulting in excellent production efficiency.

[0079] [ka] [In the formula, R represents a luminescent dye skeleton.]

[0080] In the above formula, R has the same meaning as R in the above general formula (1).

[0081] <Synthesis Example of Exemplary Compound 1-1> The synthesis scheme of the exemplary compound 1-1 is shown below. The detailed synthesis method will be described in the Examples. The other exemplary compounds can be synthesized in the same manner. In the synthesis scheme, NMP represents N-methyl-2-pyrrolidone.

[0082] [ka]

[0083] <Luminescence quantum yield> Luminescence quantum yield is expressed as the ratio of the number of absorbed photons to the number of emitted photons. If all excited molecules return to the ground state by fluorescence, the luminescence quantum yield will be 1, but in reality it does not become 1 due to non-radiative decay.

[0084] Nonradiative deactivation is a transition that returns to the ground state without emitting fluorescence. In addition to relaxation to the triplet state due to intersystem crossing, there are also internal conversions in which the energy of the electronic state is converted into vibrational energy or the like, which ultimately becomes thermal energy, and energy transfers in which energy is transferred to other molecules.

[0085] If the rate constants of the fluorescent transition and non-radiative transition of a molecule in an excited state are Kf and Knr, respectively, the luminescence quantum yield Φ (%) is Φ(%)=(Kf / (Kf+Knr))×100 It is expressed as:

[0086] Therefore, in order to improve the luminescence quantum yield, it is necessary to suppress the non-radiative deactivation of molecules in an excited state.

[0087] In the present invention, the luminescent compound of the present invention has an ionic substituent in order to suppress non-radiative deactivation. The electrostatic repulsion caused by this ionic substituent suppresses the interaction between the fat-soluble dye cores, and the aggregation between molecules can be suppressed. As a result, it is presumed that the quenching caused by the aggregation is reduced, and the luminescence is improved.

[0088] (Measurement of luminescence quantum yield) The luminescent compound of the present invention can suppress concentration quenching and exhibit a high luminescence quantum yield not only in a dilute solution but also in a highly concentrated solution or film state.

[0089] <Measurement of luminescence quantum yield in solution> The luminescence quantum yield in a solution state can be measured by dissolving a luminescent compound in 2-methyltetrahydrofuran, measuring the absolute fluorescence quantum yield using, for example, a fluorescence quantum yield measurement device (C11347-01 manufactured by Hamamatsu Photonics), and determining this as the luminescence quantum yield.

[0090] <Measurement of luminescence quantum yield in film state> The luminescent compound of the present invention is ultrasonically cleaned with isopropyl alcohol and dried with dry nitrogen gas, and then a chlorobenzene solution of each compound is dropped onto a quartz substrate (1 cm square) that has been subjected to UV ozone cleaning while being heated to 150° C. on a hot plate, and then baked for 30 minutes at 150° C. to produce a single film. The absolute fluorescence quantum yield of this single film is measured under a nitrogen atmosphere using a fluorescence quantum yield measurement device (C11347-01 manufactured by Hamamatsu Photonics), and this can be measured as the luminescence quantum yield.

[0091] [Application] The luminescent compound of the present invention can suppress concentration quenching and exhibit high luminescence quantum yield not only in a dilute solution but also in a high-concentration solution or film state. Because of such properties, the luminescent compound of the present invention can be used as a luminescent composition, a luminescent thin film, or a luminescent particle. For example, the compound can be applied to organic electronic devices such as organic electroluminescence elements as a highly efficient light-emitting material. It can also be used for bioimaging as a label in biology and medicine as a dye for a new type of fluorescent probe. The luminescent compound of the present invention, which emits fluorescence as excess energy when excited electrons return to the ground state, has wavelength conversion ability due to the difference in absorption and emission energy, and can also be used as a color conversion filter in dyes, pigments, optical filters, agricultural films, etc.

[0092] [Luminescent composition and luminescent thin film] The luminescent composition of the present invention contains the luminescent compound of the present invention. The luminescent composition of the present invention is a composition in which a dispersant is added to the luminescent compound for film formation stability, etc. Alternatively, it is preferable to use the luminescent thin film as a composition further comprising a solvent. Furthermore, the luminescent thin film of the present invention contains the luminescent compound of the present invention. Specifically, the luminescent thin film can be produced by forming the luminescent composition of the present invention into a thin film.

[0093] Examples of the dispersant include (meth)acrylate resins, polyester resins, polyamide resins, polyimide resins, polystyrene resins, polyepoxy resins, polyester resins, amino resins, fluorine resins, phenol resins, polyurethane resins, polyethylene resins, polypropylene resins, polyvinyl chloride resins, polyvinyl alcohol resins, polyether resins, polyether ketone resins, polyphenylene sulfide resins, polycarbonate resins, and aramid resins, and are preferably polystyrene resins, polyethylene resins, polypropylene resins, and polyvinyl chloride resins. Copolymers of these resins are also preferred.

[0094] A (meth)acrylate resin is synthesized by homopolymerizing or copolymerizing various methacrylate or acrylate monomers, and a desired (meth)acrylate resin can be obtained by changing the monomer type and monomer composition ratio. In the present invention, a (meth)acrylate monomer can be copolymerized with a copolymerizable monomer having an unsaturated double bond other than a (meth)acrylate monomer, and further, a poly(meth)acrylate resin can be mixed with a plurality of other resins.

[0095] Examples of monomer components forming the (meth)acrylate resin used in the present invention include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, acetoacetoxyethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, di(ethylene glycol) ethyl ether (meth)acrylate, ethylene glycol methyl ether (meth)acrylate, isobornyl (meth)acrylate, ethyltrimethylammonium chloride (meth)acrylate, trifluoroethyl (meth)acrylate, octafluoropentyl (meth)acrylate, 2-acetamidomethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-dimethylamino ... ethylaminoethyl (meth)acrylate, 3-trimethoxysilanepropyl (meth)acrylate, benzyl (meth)acrylate, tridecyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate, 2-diethylaminoethyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate Examples of the acrylates include ethyl (meth)acrylate and glycidyl (meth)acrylate, and preferred are (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, acetoacetoxyethyl (meth)acrylate, benzyl (meth)acrylate, tridecyl (meth)acrylate, dodecyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate.

[0096] The polystyrene resin may be a homopolymer of a styrene monomer, or a random copolymer, block copolymer, or graft copolymer obtained by copolymerizing a monomer having another unsaturated double bond that is copolymerizable with the styrene monomer. In addition, it may also include a blend or polymer alloy obtained by blending such a polymer with another polymer. Examples of the styrene monomer include styrene, α-methylstyrene, α-ethylstyrene, and α-methylstyrene-p-methylstyrene. Examples of the styrene include nuclear alkyl-substituted styrenes such as styrene, o-methylstyrene, m-methylstyrene, and p-methylstyrene, and nuclear halogenated styrenes such as o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, p-bromostyrene, dichlorostyrene, dibromostyrene, trichlorostyrene, and tribromostyrene. Of these, styrene and α-methylstyrene are preferred.

[0097] Examples of resins used in the present invention that are obtained by homopolymerizing or copolymerizing these include copolymer resins such as benzyl methacrylate / ethyl acrylate or butyl acrylate, copolymer resins such as methyl methacrylate / 2-ethylhexyl methacrylate, copolymer resins such as methyl methacrylate / methacrylic acid / stearyl methacrylate / acetoacetoxyethyl methacrylate, copolymer resins of styrene / acetoacetoxyethyl methacrylate / stearyl methacrylate, copolymers of styrene / 2-hydroxyethyl methacrylate / stearyl methacrylate, and copolymer resins such as 2-ethylhexyl methacrylate / 2-hydroxyethyl methacrylate.

[0098] The content of the luminescent compound in the luminescent composition and luminescent thin film of the present invention is preferably 0.001 parts by mass at the lower limit and 50 parts by mass at the upper limit relative to 100 parts by mass of the dispersant. When the content of the luminescent compound is within this range, the composition has high transparency and can display an image with high brightness when irradiated with light. The more preferred lower limit of the content of the luminescent compound is 0.01 parts by mass, the more preferred upper limit is 10 parts by mass, the even more preferred lower limit is 0.05 parts by mass, the even more preferred upper limit is 8 parts by mass, the particularly preferred lower limit is 0.1 parts by mass, and the particularly preferred upper limit is 5 parts by mass. The luminescent thin film of the present invention can be used appropriately in a thickness range of 0.1 nm to 1 mm.

[0099] [Luminous particles] The luminescent particles of the present invention contain the luminescent compound of the present invention. The luminescent particles may be ones in which the luminescent compound is adsorbed on the particle surface, or ones in which the luminescent compound is encapsulated. For example, the luminescent particles can be prepared by aggregating a luminescent compound in a dispersion of polymer particles in a liquid. Alternatively, the luminescent particles may be prepared by encapsulating a luminescent compound in a swelling polymer, which absorbs the solvent and expands in volume when the polymer particles are immersed in the solvent.

[0100] The polymer particles may be commercially available or may be synthesized by a conventionally known method.The conventionally known method is not particularly limited, but may include dispersion polymerization, suspension polymerization, emulsion polymerization, etc., and emulsion polymerization is preferred.The monomer that is the raw material of the polymer may be any of the various monomers listed as the dispersant. In addition, the solvent used when a light-emitting compound is aggregated in a polymer dispersion in a liquid is not particularly limited, and any known solvent can be used. The volume average particle size of the polymer particles is preferably within a range of 0.01 to 50 μm, more preferably 0.02 to 40 μm, and even more preferably 0.04 to 20 μm. When the volume average particle diameter is within the above range, the obtained luminescent particles can be applied to various applications. Specifically, the volume average particle diameter can be measured using a laser diffraction / scattered light particle size distribution measuring device, LS13320 model. The weight average molecular weight of the polymer particles is preferably within a range of 1,000 to 1,000,000, more preferably 5,000 to 800,000, and further preferably 10,000 to 600,000. The polymer particles contained in the luminescent particles of the present invention may be of one type or of two or more types, but are usually of one type.

[0101] [Organic electroluminescence element] An organic electroluminescence element (organic EL element) has a structure in which an emitting layer containing a light-emitting compound (light-emitting material) is sandwiched between a cathode and an anode on a substrate, and emits light by injecting electrons and holes into the emitting layer, generating excitons by recombination, and utilizing the emission of light when the excitons are deactivated. The luminescent compound of the present invention can be applied to an organic EL element as a fluorescent material. Preferred examples of the layer structure of the organic EL element are shown below. (i) Anode / light-emitting layer / electron transport layer / cathode (ii) anode / hole transport layer / light emitting layer / electron transport layer / cathode (iii) anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode (iv) anode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode (v) Anode / anode buffer layer / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / cathode Here, the hole transport layer includes the concepts of a hole injection layer and an electron blocking layer.

[0102] The light-emitting layer is a layer in which electrons and holes injected from the electrode, the electron transport layer, and the hole transport layer recombine to emit light, and the light-emitting portion may be within the light-emitting layer or at the interface between the light-emitting layer and an adjacent layer. The light-emitting compound of the present invention can be used in the light-emitting layer. Since there is little concentration quenching, a high luminescence quantum yield can be achieved even in the form of a film.

[0103] In addition, when the light-emitting compound of the present invention is used as a light-emitting material for an organic EL device, a known host compound can be used as a dispersant. Specific examples thereof include compounds described in the following documents, but the present invention is not limited thereto.JP-A-2001-257076, JP-A-2002-308855, JP-A-2001-313179, JP-A-2002-319491, JP-A-2001-357977, JP-A-2002-334786, JP-A-2002-8860, JP-A-2002-334787 Publication No. 2002-15871, Publication No. 2002-334788, Publication No. 2002-43056, Publication No. 2002-33478 Publication No. 9, Publication No. 2002-75645, Publication No. 2002-338579, Publication No. 2002-105445, Publication No. 2002-3435 Publication No. 68, Publication No. 2002-141173, Publication No. 2002-352957, Publication No. 2002-203683, Publication No. 2002-3 Publication No. 63227, Publication No. 2002-231453, Publication No. 2003-3165, Publication No. 2002-234888, Publication No. 2003-2 Publication No. 7048, Publication No. 2002-255934, Publication No. 2002-260861, Publication No. 2002-280183, Publication No. 2002-2002 -299060, 2002-302516, 2002-305083, 2002-305084, 20 02-308837, U.S. Patent Application Publication No. 2003 / 0175553, U.S. Patent Application Publication No. 2006 / 0280965, U.S. Patent Application Publication No. 2005 / 0112407, U.S. Patent Application Publication No. 2009 / 0017330, U.S. Patent Application Publication No. 2009 / 0030202, U.S. Patent Application Publication No. 2005 / 0238919, International Publication No. 2001 / 039234, International Publication No. 2009 / 021126, International Publication No. 2008 / 056746, International Publication No. 2004 / 093207, International Publication No. 2005 / 089025, International Publication No. 2007 / 063796, WO 2007 / 063754, WO 2004 / 107822, WO 2005 / 030900, WO 2006 / 114966, WO 2009 / 086028, WO 2009 / 003898, WO 2012 / 023947, JP 2008-074939 A, JP 2007-254297 A, European Patent Specification No. 2034538, WO 2011 / 055933, WO 2012 / 035853, JP 2015-38941 A, and the like.

[0104] The light-emitting layer may contain other known materials such as fluorescent materials and phosphorescent materials. The charge injection layer is a layer provided between the electrode and the light-emitting layer to reduce the driving voltage and improve the luminance of the light emitted, and includes a hole injection layer and an electron injection layer. The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, the hole injection layer and the electron blocking layer also have the function of the hole transport layer. The hole transport layer may be a single layer or a plurality of layers.

[0105] The electron transport layer is made of a material having a function of transporting electrons, and in a broad sense, the electron transport layer also includes an electron injection layer and a hole blocking layer. The electron transport layer may be provided as a single layer structure or a laminated structure of multiple layers. Examples of the blocking layer include a hole blocking layer and an electron blocking layer, which are layers that are provided as necessary in addition to the respective constituent layers of the organic functional layer described above. The substrate, electrodes, charge injection layer, hole transport layer, electron transport layer, blocking layer, and the like can be made of known materials.

[0106] [Bioimage] The luminescent compound of the present invention can be used as a fluorescent dye. In bioimaging applications, after staining living cells with the fluorescent dye, the luminescent color of the stained cells can be examined, and the luminescent color can reveal the environment surrounding the cells, enabling imaging of the intracellular environment. For example, in order to know the expression state of a target biological substance, a technique is known in which fluorescent labeling is performed using fluorescent-substance-aggregated nanoparticles to which a biological substance recognition moiety capable of recognizing and binding to the target biological substance is bound. Specifically, a tissue specimen is stained with fluorescent-substance-aggregated nanoparticles, the peaks of the luminance distribution of fluorescent spots are analyzed to obtain the average luminance value per particle, the number of particles in each spot is calculated, and the calculated particle numbers are compared to evaluate the expression level of the target biological substance. The luminescent compound of the present invention has a high luminescence quantum yield, and therefore can increase the luminance value per particle of the fluorescent substance-holding nanoparticles, and therefore has the advantage of being able to quantitatively detect trace amounts of biological substances when applied to such bioimages.

[0107] [Color conversion filter] The color conversion filter can be used in image display devices such as liquid crystal displays (LCDs), plasma display panels (PDPs), electroluminescence displays (ELDs), cathode ray tube displays (CRTs), fluorescent display tubes, field emission displays, etc., and in lighting devices such as LED lighting, electroluminescence lighting, etc. When used in image display devices, it is possible to correct the hue to a preferred level without reducing the display luminance, and when used in lighting devices (particularly LED lighting), it is possible to obtain white light that feels more natural. The color conversion filter may be the same as a conventional optical filter except that it contains at least one of the luminescent compounds of the present invention that emit fluorescence, and there is no limitation on its configuration. For example, like the conventional ones, it has at least a support, and if necessary, it can have various functional layers such as an optical functional layer, an undercoat layer, an anti-reflection layer, a hard coat layer, and a lubricant layer. In the color conversion filter, the luminescent compound of the present invention that emits fluorescence may be contained in either the support or various functional layers, and is usually preferably contained in the support or the optical functional layer. In addition, the size and shape of the color conversion filter are not particularly limited and are appropriately determined according to the application. EXAMPLES

[0108] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In the following examples, unless otherwise specified, the operations were performed at room temperature (25°C). Furthermore, unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass", respectively.

[0109] [Synthesis of Exemplary Compound 1-1 of the Present Invention] The exemplary compound 1-1 of the present invention was synthesized according to the synthesis procedure shown below. 2,6-Diisopropylaniline and propionic acid were added to 1,6,7,12-tetrachloroperylenetetracarboxylic dianhydride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product number W01COBQA-7294) and reacted by refluxing in a solvent for 3 hours. The mixture was purified by silica gel column chromatography to obtain intermediate 1 as an orange solid (yield 80%). Next, the obtained intermediate 1 was dissolved in N-methylpyrrolidone (NMP), 2-phenylphenol was added, and potassium carbonate (K 2 CO 3 The reaction was carried out in the presence of 1,2-dichloromethane at 140° C. for 18 hours. The mixture was purified by silica gel column chromatography to give intermediate 2 as a dark red solid (yield 68%). Next, the intermediate 2 was reacted with excess concentrated sulfuric acid at room temperature for 2 days. The product was purified by medium pressure reverse phase column chromatography to obtain the exemplary compound 1-1 of the present invention as a dark purple solid (yield 30%). The synthesis scheme is shown below.

[0110] [ka]

[0111] The structures of comparative compounds 1 and 2 used in the comparative examples are shown below. [ka]

[0112] [Evaluation of luminescence quantum yield in doped film] After ultrasonic cleaning with isopropyl alcohol and drying with dry nitrogen gas, a quartz substrate (1 cm square) was subjected to UV ozone cleaning treatment, and a solution of the synthesized exemplary compound 1-1 of the present invention and polymethyl methacrylate (PMMA) in propylene glycol monomethyl ether (PGME) was dropped onto the substrate, and a film was formed by spin coating. The absolute fluorescence quantum yield was measured under a nitrogen atmosphere using a fluorescence quantum yield measurement device (Hamamatsu Photonics C11347-01), and this was taken as the luminescence quantum yield in the doped film state. The quantum yield when the dye doping concentration is 1% is taken as 1, and the change in quantum yield when the doping concentration is increased is shown in FIG. The absolute fluorescence quantum yields of the comparative compounds 1 and 2 were also measured in the same manner, and the changes in the quantum yields with increasing dye doping concentrations are shown in FIG.

[0113] From the results shown in FIG. 1, it is understood that the luminescent compound of the present invention (exemplified compound 1-1) can suppress concentration quenching that occurs with an increase in doping concentration, and is superior in luminescence properties, compared to comparative compounds 1 and 2.

[0114] [Example 2] <Preparation of luminescent particles> The synthesized luminescent compound of the present invention (exemplified compound 1-1) was added to 22 mL of water and dissolved. Then, 2 mL of a 5% aqueous solution of Emulsion (registered trademark) 430 (polyoxyethylene oleyl ether, manufactured by Kao Corporation), an emulsifier for emulsion polymerization, was added to the solution. The solution was heated to 70°C while being stirred on a hot stirrer, and 0.65 g of Nikalac MX-035 (manufactured by Nippon Carbide Industries Co., Ltd.), a raw material for melamine resin, was added to the solution. Furthermore, 1000 μL of a 10% aqueous solution of dodecylbenzenesulfonic acid (Kanto Chemical Co., Ltd.) was added to this solution as a surfactant, and the mixture was heated and stirred at 70° C. for 50 minutes. The mixture was then heated to 90° C. and heated and stirred for 20 minutes. The resulting dispersion of dye resin particles was washed with pure water to remove impurities such as excess resin raw material and fluorescent dye. Specifically, the mixture was centrifuged at 20,000G for 15 minutes in a centrifuge (Kubota Micro Refrigerated Centrifuge 3740), the supernatant was removed, and then ultrapure water was added and ultrasonically irradiated to redisperse the mixture. The process of centrifugation, removal of the supernatant, and washing by redispersion in ultrapure water was repeated five times. The absolute fluorescence quantum yield of the resulting aqueous dispersion of fluorescent particles was measured using a fluorescence quantum yield measurement device (C11347-01, Hamamatsu Photonics), and this was taken as the luminescence quantum yield of the luminescent particles. For the comparative compounds 1 and 2, the preparation of luminescent particles and the measurement of luminescence quantum yield were carried out in the same manner. The amount of dye was adjusted so that the dye concentration in the particles was 20%.

[0115] [Table 1]

[0116] The results shown in Table I show that the luminescent compound of the present invention (exemplified compound 1-1) can suppress concentration quenching that occurs with an increase in doping concentration, and is superior in luminescence properties, compared to comparative compounds 1 and 2. [Industrial Applicability]

[0117] The present invention can be utilized in a luminescent compound which is highly water-soluble and has excellent luminescence properties even under high concentration conditions due to its concentration quenching suppression effect, a method for producing the luminescent compound, a luminescent composition, a luminescent thin film, and a luminescent particle.

Claims

1. A luminescent compound having the following compound 1-1: 【Chemistry 1】

2. A method for producing a luminescent compound according to claim 1, comprising the steps of: A method for producing a luminescent compound, comprising the steps of sulfonating a dye molecule having a 2-biphenyloxy group to introduce one sulfo group into each benzene ring. 【Chemistry 2】 [In the formula, R represents a luminescent dye skeleton.]

3. A luminescent composition comprising the luminescent compound according to claim 1.

4. A luminescent thin film comprising the luminescent compound according to claim 1.

5. A luminescent particle comprising the luminescent compound according to claim 1.

Images