Iridium complexes used as photosensitizers

Abstract

The present invention relates to compounds of formula (I). It also relates to a process for preparing a compound as well as to the use of these compounds as a medicament, in particular in the treatment of cancer.

Description

[0001]DESCRIPTION IRIDIUM COMPLEXES USED AS PHOTOSENSITIZERS The present invention relates to novel compounds, their process for preparation and their use as a medicament, for example in the treatment of cancer or in the treatment of antibiotic-resistant diseases. Photodynamic therapy (PDT) exploits photo-activatable compounds for therapeutic use against cancer and age-related macular degeneration (AMD). PDT consists of treating a patient with a molecule called a photosensitizer. This photosensitizer can be administered topically, for example by means of a cream to be applied to the skin. Alternatively, this photosensitizer can be administered by means of a tablet or by injection. The principle of PDT is that the photosensitizer must accumulate preferentially in the area to be treated until it reaches a determined peak concentration.Once this peak concentration is reached, the curative treatment is carried out by light irradiation of the said area. Thus, in photodynamic therapy, the photosensitizers used must ideally be harmless in the absence of light, and on the contrary, a toxicity which must be activated under light irradiation. The operation of PDT is based on the fact that, when they are subjected to a certain wavelength, the photosensitizers become excited molecules which transmit their energy to the oxygen molecules present in the tumor to be treated. The excited oxygen produces singlet oxygen and / or reactive oxygen species (ROS), which cause the death of cancer cells. Photodynamic therapy thus has the advantage of being a non-invasive and selective technique for treating cancerous tumors, allowing only the desired area to be treated.It is therefore desirable to have photosensitizers that can implement this technique. Iridium(III)-based complexes (hereinafter referred to as Ir(III)) have been proposed as photosensitizers, due to their interesting photophysical properties, such as their photostability. Four phosphorescent cationic cyclometalated iridium(III) complexes containing a benzimidazole group were designed and synthesized, Wang FX, Chen MH, Lin YN, et al. Dual Functions of Cyclometalated Iridium(III) Complexes: Anti-Metastasis and Lysosome-Damaged Photodynamic Therapy. ACS Appl Mater Interfaces. 2017;9(49):42471-42481. These Ir(III) complexes can effectively inhibit several cancer processes, such as migration, invasion, colony formation, and angiogenesis. Under light irradiation (1.2 J cm. -2), these complexes induce apoptosis through lysosomal damage attributed to the generation of singlet oxygen and reactive oxygen species. However, in view of the clear advantages of photodynamic therapy, it would be interesting to find compounds even more effective than those already known. The present invention relates to compounds of general formula (I): or salt of these compounds, formula in which: - R 1 , R 2 , R 3 and R 4 are chosen independently of each other as being a hydrogen atom or a halogen atom; - R 5 is selected from a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group, a C2-C6-alkynyl group or a polyethylene glycol (PEG) group of the following formula: in which n is an integer ranging from 1 to 4; - L is chosen to be a single bond or linking group chosen from: - R 6 and R 7 are independently selected from one another as being a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group or a C2-C6-alkynyl group, and - R 8 and R 11 are independently selected from a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group, a C2-C6-alkynyl group or a group of general formula (II) - R 9 and R 10 are chosen independently of each other as being a hydrogen atom or a C1-C6-alkoxy group, preferably a methoxy group. The present invention also relates to compounds of general formula (I): or salt of these compounds, formula in which: - R 1 , R 2 , R 3 and R 4 are chosen independently of each other as being a hydrogen atom or a halogen atom; - R 5 is selected from a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group, a C2-C6-alkynyl group or a polyethylene glycol (PEG) group of the following formula: in which n is an integer ranging from 1 to 4; - L is chosen to be a single bond or linking group chosen from: ; ; And - R 6 and R 7 are independently selected from one another as being a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group or a C2-C6-alkynyl group, and - R 8 and R 11are independently selected from a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group, a C2-C6-alkynyl group or a group of general formula (II) - R 9 and R 10 are independently chosen from each other as being a hydrogen atom or a C1-C6-alkoxy group, preferably a methoxy group, and wherein, if R 1 = R 2 = R 3 = R 4 = H and if L is a single bond, then R 8is different from H.For the purposes of the present invention, the following are understood to mean: - C1-C6-alkyl group, a saturated, linear or branched hydrocarbon chain, comprising from 1 to 6 carbon atoms, such as for example a methyl, ethyl, isopropyl, tert-butyl, pentyl group, - C1-C6-hydroxyalkyl group, an HO-(C1-C6-alkyl) group, - C1-C6-alkoxy group, an –O-(C1-C6-alkyl) group, such as for example the methoxy group or the ethoxy group, - C2-C6-alkenyl group, a linear or branched hydrocarbon chain, comprising at least one unsaturation and comprising from 2 to 6 carbon atoms, such as for example an ethenyl (vinyl), propenyl group, - C2-C6-alkynyl group, a linear or branched hydrocarbon chain, comprising at least one double unsaturation and comprising from 2 to 6 carbon atoms, such as for example an acetylene, propyne, butyne group, - Halogen means a fluorine, chlorine, bromine or iodine atom, preferably a fluorine, chlorine or bromine atom.Preferably, the subject of the present invention is a compound of formula (I) as defined above, in which the following characteristics are chosen alone or in combination: - at least one substituent chosen from R. 1 , R 2 , R 3 and R 4 is a halogen atom. More preferably, R 2 is a halogen atom. Preferably, R 2 is a halogen atom and R 1 , R 3 and R 4 are hydrogen atoms; - R 1 , R 2 , R 3 and R 4 are hydrogen atoms; - R 5 is a C1-C6-alkyl group, preferably C1-C4-alkyl, more preferably a butyl group; - R 6 and R 7 are hydrogen atoms; - L is a single bond; - L is a single bond and R 8 is a C1-C6-alkyl group, preferably a methyl group; and / or - L is a single bond and R 8is the compound of formula (II). The compounds of the invention may be prepared by any method known to those skilled in the art. The invention also relates to a method for preparing the compounds of formula (I) according to the invention, comprising the following steps: - Suspending a compound of formula (III) in a mixture of CH2Cl2 / MeOH (1:1), - Addition of a compound of formula (IV) in which o R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , and R 7 are as defined above, where L is chosen as being a single bond or linking group chosen from: R o o ; gold 9 and R 10 are chosen independently of each other as being a hydrogen atom or a C1-C6-alkoxy group, preferably a methoxy group, o R 12 and R 13are independently chosen from a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group, a C2-C6-alkynyl group or a group of general formula (V) in which R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , and R 7 are as defined above, - Refluxing overnight under argon, - Adding an excess of aqueous KPF6 (sat.). The compounds according to the invention can be used as a medicament, in particular in the treatment of cancer. The compounds according to the invention can in particular be used in the treatment of cancer by dynamic phototherapy. The compounds according to the invention can be used in the treatment of antibiotic-resistant diseases. The present invention also relates to a compound of general formula (I): or salt of this compound, formula in which:- R 1 , R 2 , R 3 and R 4 are chosen independently of each other as being a hydrogen atom or a halogen atom; - R 5 is selected from a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group, a C2-C6-alkynyl group or a polyethylene glycol (PEG) group of the following formula: in which n is an integer ranging from 1 to 4; - L is chosen to be a single bond or linking group chosen from: - R 6 and R 7 are independently selected from one another as being a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group or a C2-C6-alkynyl group, and - R 8 and R 11are independently selected from a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group, a C2-C6-alkynyl group or a group of general formula (II) - R 9 and R 10 are chosen independently of each other as being a hydrogen atom or a C1-C6-alkoxy group, preferably a methoxy group, for use in the treatment of cancer by dynamic phototherapy. The present invention also relates to a compound of general formula (I): or salt of this compound, formula in which: - R 1 , R 2 , R 3 and R 4 are chosen independently of each other as being a hydrogen atom or a halogen atom; - R 5is selected from a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group, a C2-C6-alkynyl group or a polyethylene glycol (PEG) group of the following formula: in which n is an integer ranging from 1 to 4; - L is chosen to be a single bond or linking group chosen from: ; - R 6 and R 7 are independently selected from one another as being a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group or a C2-C6-alkynyl group, and - R 8 and R 11are independently selected from a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group, a C2-C6-alkynyl group or a group of general formula (II) - R 9 and R 10 are chosen independently of each other as being a hydrogen atom or a C1-C6-alkoxy group, preferably a methoxy group, for its use in the treatment of antibiotic-resistant diseases. In both of these uses, the following features may be chosen alone or in combination: - at least one substituent chosen from R 1 , R 2 , R 3 and R 4 is a halogen atom. More preferably, R 2 is a halogen atom. Preferably, R 2 is a halogen atom and R 1 , R 3 and R 4 are hydrogen atoms; - R 1 , R 2, R 3 and R 4 are hydrogen atoms; - R 5 is a C1-C6-alkyl group, preferably C1-C4-alkyl, more preferably a butyl group; - R 6 and R 7 are hydrogen atoms; - L is a single bond; - L is a single bond and R 8 is a C1-C6-alkyl group, preferably a methyl group; and / or - L is a single bond and R 8is the compound of formula (II). The compounds according to the invention can be used as sensitizers in the treatment of cancer by photodynamic therapy. These compounds have a high quantum yield of singlet oxygen generation. These compounds also have better cytotoxicity than known iridium-based complexes. These compounds can also serve as a contrast agent for luminescence microscopy imaging. The present invention is illustrated by the following examples in which: - [Fig. 1] represents photos of cells of cancer lines and the compound IrL 1according to the invention obtained by confocal microscopy, after 2 h, 4 h or 24 h in the dark at 37 °C, - [Fig.2] represents photos of cells of cancer lines and the compound Ir 2 2L according to the invention obtained by confocal microscopy, after 2 h, 4 h or 24 h in the dark at 37 °C, EXPERIMENTAL PART In the following examples: Commercially available reagents were purchased from Sigma-Aldrich, Alfa Aesar, Acros Organics, TCI Chemical, Merck, Strem or Fluorochem and used as received, unless otherwise indicated. Solvents were obtained from the same commercial sources and used without further purification. For moisture-sensitive reactions, the glassware was oven-dried before use. The NMR spectra 1 H were recorded on a Brucker advance III 400 MHz spectrometer equipped with a BBO probe and on a Brucker advance III 500 MHz spectrometer equipped with a CryoProbe Prodigy in a deuterated solvent (CDCl3, DMSO-d6 or CD2Cl2) and the data are reported as follows: chemical shift (δ) in ppm of tetramethylsilane with the solvent as internal indicator (CDCl37.26 ppm, dmso-d 6 2.50 ppm, CD2Cl25.32 ppm), multiplicity (s = singlet, d = doublet, t = triplet, q = quartet, p = pentet, m = multiplet or overlap of non-equivalent resonances), integration. The NMR spectra 13 C{ 1 H} were recorded at either 101 MHz or 126 MHz in an appropriate deuterated solvent and the data are reported as follows: chemical shift in ppm of tetramethylsilane with the solvent as internal indicator (CDCl3 77.16 ppm, DMSO-d 6 39.52 ppm, CD2Cl253.84 ppm). NMR spectra 19F were recorded at 376 MHz and 470 MHz with the appropriate deuterated solvent spectrum. Absorption spectra were recorded on a Cary 300 UV−visible spectrophotometer (Varian) and emission spectra (in solution and at 77 K) were recorded on a Fluoromax 4® (Horiba) or FLS-1000® (Edinburgh Instruments) equipped with automatic filters to remove harmonic bands. Quartz cuvettes with a 1 cm path length were used. Lifetimes were measured using an LP900 spectrometer with a flashlamp-pumped Q-switched Nd:Yag laser operating at 355 nm and with a photomultiplier (PMT) detector, or with a picosecond laser diode operating at 410 nm and using time-correlated single photon counting (TCSPC, PicoHarp 300) detection.Calculation of the singlet oxygen quantum yield: an FLS-1000® (Edinburgh Instruments) equipped with automatic filters to eliminate harmonic bands with an InGaAs 870-1650 nm detector cooled to -20°C with a Peltier. The quantum efficiency of singlet oxygen generation (Φ∆) was calculated using the Stern-Volmer model according to the equation ΦΔ / ΦΔr = [Ar / Ax][nx. 2 / nr 2 ][Dx / Dr] for dilute solutions having an optical density less than 0.1, where Φ∆ / Φ∆r is the ratio of the singlet oxygen luminescence quantum yield, Ar / Ax is the absorbance ratio at the excitation wavelength and Dx / Dr is the luminescence (surface) ratio. “r” means reference (phenalenone, Φ∆_r =1 in chloroform). Reaction scheme for the preparation of a monomer according to the invention Scheme 1: i) DMSO, butylamine, 100°C; ii) Na2S2O5, methoxyethanol / H2O reflux, iii) MeOH / DCM, L 1, Ar, reflux and iv) KPF6aq (Sat.). Reaction scheme for the preparation of a dimer according to the invention Scheme 2: i) DMF, 1-bromobutane, NaH, 0°C to 60°C; ii) Na2S2O5, DMF / H2O reflux, iii) MeOH / DCM, L 2 , Ar, reflux and iv) KPF6aq (Sat.). Reaction scheme for the preparation of the ligand for the preparation of a trimer according to the invention i) Pd(dba)2, Xantphos, Cs2CO3, Dioxane, 100 °C; ii) Na2S2O5, DMF / H2O Preparation of intermediate compounds Preparation of compound 1: N-butyl-3-aminobenzidine R = nC4H9 In a round-bottom flask, DMSO was added to a mixture of 4-fluoro-3-nitrototoluene (2 g, 12.9 mmol) and n-butylamine (3.4 mL, 34.8 mmol). The flask was sealed with a rubber stopper and the mixture was heated at 60°C overnight. The color of the mixture changed rapidly from yellow to orange. At room temperature, 30 mL of ethyl acetate was added to this orange solution and the organic phase was extracted three times with water and washed with brine. The organic phase was dried over MgSO4 and the product was isolated as a light orange translucent solid (2.2 g, 88%). The product was used without further purification. NMR 1 H (400 MHz, CDCl3) δ 8.04 (d, J = 8.8 Hz, 2H), 6.61 (d, J = 1.8 Hz, 2H), 6.43 (dd, J = 8.8, 1.9 Hz, 2H), 3.28 (t, J = 7.1 Hz, 2H), 2.33 (s, 3H), 1.71 (p, J = 7.3 Hz, 2H), 1.48 (h, J = 14.6 Hz, 2H), 0.98 (t, J = 7.3 Hz, 3H). NMR 13C (101 MHz, CDCl3) δ 147.8, 145.8, 130.0, 126.9, 117.0, 113.5, 42.8, 31.1, 22.3, 20.4, 13.9. HRMS (ESI) calculated m / z 209.12845 for [C11H16N2O2+H] + ; found m / z 209.12747. Preparation of 2-(5-bromopyridin-2-yl)-1-butyl-5-methyl-1-H-benzimidazol: Ligand 1 (L 1 ) In a round-bottom flask, a mixture of methoxyethanol / water (25 mL, 4:1) was added to compound 1 (1.0 g, 4.8 mmol) and bromopyridinecarboxaldehyde (0.9 g, 4.8 mmol). When the solids were dissolved, Na2SO4 (7.7 g, 44.2 mmol) was added, and the solution was heated at 100°C overnight. At room temperature, water (30 mL) was added, followed by 30 mL of ethyl acetate. The phases were separated, and the organic phase was washed 3 times with water, once with brine, and then dried over Na2SO4. After evaporation of the solvent, the compound was obtained as a light beige solid (814 mg, 49%) and used without further purification. NMR 1H (400 MHz, CDCl3) δ 8,70 (d, J = 2,4 Hz, 1H), 8,31 (d, J = 8,5 Hz, 1H), 7,91 (dd, J = 8,5 Hz, J = 2,4 Hz, 1H), 7,69 (d, J = 8,2 Hz, 1H), 7,19 (s, 1H), 7,12 (dd, J = 8,3 Hz, J =1,8 Hz, 1H), 4,73 (t, J = 7,6 Hz, 2H), 2,52 (s, 3H), 1,89 – 1,77 (m, 2H), 1,37 (h, J = 7,4 Hz, 2H), 0,94 (t, J = 7,4 Hz, 3H). RMN 13 C (101 MHz, CDCl3) δ 149,6, 149,3, 148,4, 140,8, 139,4, 137,0, 133,7, 125,7, 124,5, 121,0, 119,7, 110,1, 45,4, 32,3, 22,1, 20,2, 13,8. HRMS (ESI) calculé m / z 344,07437 pour [C17H18BrN3+H] +; found m / z 344.07569. Preparation of compound 2 N,N-dibutyl-3,3'-diaminobenzidine To an ice-cold solution of 3,3'-diamino-4,4'-dinitrobiphenyl (1 g, 3.7 mmol) in dry DMF (20 mL) was added sodium hydride (60% in oil, 438 mg, 11.0 mmol) portionwise over 10 min, followed by 1-bromobutane (1.2 mL, 11.1 mmol). The mixture was heated at 60°C overnight and then, at room temperature, water was added. The solution was extracted 3 times with ethyl acetate and the organic phase was washed 1 time with water and brine, and finally dried over MgSO4. The dried organic phase was filtered with cotton and the solvent was evaporated under reduced pressure. A chromatography column (SiO2) with cyclohexane / acetyl acetate as eluent (6:4) gave compound 2 as a dark orange solid (620 mg, 44%). NMR 1H (400 MHz, CDCl3) δ 8.34 (t, J = 2.1 Hz, 2H), 8.09 (t, J = 5.3 Hz, 2H), 7.68 (dd, J = 9.0, 2.6 Hz, 2H), 6.93 (d, Jd = 9, 2.3). 7.2, 5.1 Hz, 4H), 1.74 (p, J = 7.4Hz, 4H), 1.50 (h, J = 7.3 Hz, 4H), 1.00 (t, J = 7.3 Hz, 6H). 13C NMR (101 MHz, CDCl3) δ 144.8,134.3, 132.0, 126.2, 123.6, 114.8, 43.0, 31.2, 20.4, 13.9. HRMS (ESI) calculated m / z 387.20268 for [C20H26O4N4+H] + ; found m / z 387.20183. Preparation of 2,2′-bis(5-bromopyridin-2-yl)-1,1′-dibutyl-1-H,1-H-5,5′-bibenzimidazole : Ligand 2 (L2) Compound 2 (1 g, 2.6 mmol) and then 5-bromo-2-pyridinecarboxaldehyde (967 mg, 5.2 mmol) were added to DMF (18 mL) at room temperature. After complete dissolution under stirring, solid Na2SO4 (8.4 g, 48 mmol) was added followed immediately by the addition of water (4.5 mL). The reaction mixture was stirred at 100°C overnight to give a solution containing a pale yellow suspension. At room temperature, the reaction was quenched by adding water and the precipitate was filtered with a Büchner funnel equipped with Celite®. The solid was washed extensively with water and the top layer of the Celite® cake was scraped off and dissolved / suspended in CH2Cl2. The solution was washed 3 times with water, then 1 time with brine and finally the organic phase was dried over NaSO4. After filtration, the solvent was evaporated. Purification was carried out by column chromatography (SiO2) with a tertiary mixture as eluent (CH2Cl2 / Acetone / Et3N, 9.49:0.5:0.01).The product was obtained in the form of a light beige solid (885 mg, 52%). The elemental analysis for C32H30Br2N6, computed. C, 58.36%, H, 4.60%, N, 12.77%; found C, 58.14%, H, 4.54%, N, 12.68%. NMR. 1 H (400 MHz, CDCl3) δ 8.76 (dd, J = 2.4 Hz, J = 0.8 Hz, 2H,, 8.38 (dd, J = 8.5 Hz, J = 0.8 Hz, 2H), 8.10 (d, J = 1.8 Hz ( J d 7, =9 H = 2.4 Hz, 2H), 7.68 (dd, J = 8.5 Hz, J = 1.6 Hz, 2H), 7.53 (d, J = 8.5 Hz, 2H), 4.84 (t, J = 7.5 Hz, 6H), 1.90 (H5, J = 7, 4.4 7.3 Hz, 7H), 0.97 (t, J = 7.3 Hz, 13H NMR). 13 C (101 MHz, CDCl3) δ 149.9 (C12), 149.6 (, 149.3, 143.5, 139.7, 137.2, 136.3, 126.1, 124.0, 121.8, 118.8 ( 32.6 (C17), 20.4 (C18), 14.0 (C19) calculated m / z 659.09537 for [C32H30Br2N6+H] +; found m / z 659.09361. General procedure for the preparation of monomeric, dimeric and trimeric complexes The appropriate precursor µ-Cl2Ir2 (1 eq., here dichlorotetrakis(2-(2-pyridinyl)phenyl)diiridium(III)) was suspended in a mixture of CH2Cl2 / MeOH (1:1) and the ligand (2 eq. in the case of the monomer, 1-0.9 eq. for the dimer, and 0.6-0.5 eq. for the trimer) was added. The yellow solution quickly turned orange after a few minutes and the reaction was refluxed overnight under Ar. At room temperature, the solvent was concentrated to 1 / 3 and an excess of aqueous KPF6 (sat.) was added dropwise. An orange precipitate appeared quickly and the suspension was stirred for another 10 minutes. The solution was filtered using a Millipor® apparatus. The solid was washed with water, ice-cold methanol (5 mL), and finally with ice-cold diethyl ether.The complexes were isolated as dark yellowish to orange-red powders. EXAMPLE 1 Preparation of bis[2-phenylpyridinato-C. 2 ,N]-[ 2-(5-bromopyridin-2-yl)-1-butyl-5- methyl-1-H-benzimidazolyl-N,N']iridium(III) hexafluorophosphate: Compound hereinafter referred to as monomer IrL 1 R = nC4H9 The general procedure was applied with the precursor µ-Cl2Ir2 (50 mg, 47 mmol), the ligand L 1 (32 mg, 93 mmol) and 10 mL of solvent. The monomer was isolated after recrystallization with diethyl ether vapor diffusion from CH2Cl2 solution, as a dark yellowish solid (87 mg, 93%). HRMS (ESI) calculated m / z 844.16072 for [C39H34BrIrN5] + ; found m / z 844.15908. This compound has a singlet oxygen generation quantum yield (ΦΔ), recorded in CHCl3, of 66%. EXAMPLE 2 Preparation of bis[2-phenylpyridinato-C 2 ,N]-µ-[2,2'-bis(5-bromopyridin-2-yl)-1,1'- Compound hereinafter called dimer Ir 2 2L R = nC4H9 The general procedure was applied with the precursor µ-Cl2Ir2 (50 mg, 47 mmol), the ligand L 2 (31 mg, 47 mmol) and 10 mL of solvent. The dimeric mixture was isolated after recrystallization with diethyl ether vapor diffusion from CH2Cl2 solution, as a dark yellowish solid (72 mg, 79%). HRMS (ESI) calculated m / z 826.13735 for [C76H62Ir2Br2N10] 2+ ; found m / z 829.13747. EA calculated for [C76H62Ir2Br2N10P2F12] C, 46.52; H, 3.21; N, 7.19; found C, 47.09; H, 3.04; N, 7.25. This compound has a singlet oxygen generation quantum yield (φΔ), recorded in CHCl3, of 78%. EXAMPLE 3 Preparation of bis[2-phenylpyridinato-C 2,N]-[ 2-(5-pyridin-2-yl)-1-butyl-5-methyl-1- H-benzimidazolyl-N,N']iridium(III) Compound hereinafter referred to as monomer H The general procedure was applied with the precursor µ-Cl2Ir2 (140 mg, 0.13 mmol), the ligand 2-pyridin-2-yl-1-butyl-5-methyl-1-H-benzimidazole (70 mg, 0.26 mmol) and 10 ml of solvent. The monomer was isolated after recrystallization with diethyl ether vapor diffusion from CH2Cl2 solution, in the form of a dark yellowish solid (87 mg, 93%). EXAMPLE 4 Preparation of bis[2-phenylpyridinato-C 2 ,N]-[2-(5-chloropyridin-2-yl)-1-butyl-5- methyl-1-H-benzimidazolyl-N,N']iridium(III) Compound hereinafter referred to as monomer Cl The general procedure was applied with the precursor µ-Cl2Ir2 (180 mg, 0.17 mmol), the ligand 2-(5-chloropyridin-2-yl)-1-butyl-5-methyl-1-H-benzimidazole (10 mg, 0.34 mmol) and 10 ml of solvent. The monomer was isolated after recrystallization with diethyl ether vapor diffusion from CH2Cl2 solution, in the form of a dark yellowish solid (164 mg, 51% ). EXAMPLE 5 Preparation of bis[2-phenylpyridinato-C 2 ,N]-[2-(5-fluoropyridin-2-yl)-1-butyl-5- 1-H-benzimidazolyl-N,N']iridium(III) Compound hereinafter referred to as monomer F The general procedure was applied with the precursor µ-Cl2Ir2 (100 mg, 0.09 mmol), the ligand 2-(5-fluoropyridin-2-yl)-1-butyl-5-methyl-1-H-benzimidazole (60 mg, 0.21 mmol) and 10 ml of solvent. The monomer was isolated after recrystallization with diethyl ether vapor diffusion from CH2Cl2 solution, in the form of a yellow solid (175 mg, 90%). EXAMPLE 6 The localization of cancer cell lines A549, HT29 and HeLa to IrL monomer complexes was observed 1 and Ir2L dimer 2 according to the invention by confocal microscopy imaging. In vitro cytotoxicity tests were also carried out on the same cell lines with the complexes according to the invention monomer IrL 1, monomer H, monomer F and monomer Cl. The conditions for performing these tests and the results obtained are described below. Cell lines and culture The human lung adenocarcinoma A549 and colon carcinoma HT29 cell lines were obtained from LGC Standard (Molsheim, France). All cells were routinely tested for the presence of mycoplasma (Mycoalert® Mycoplasma Detection Kit, Lonza, Rockland, ME, USA) and used within three months of thawing. The cells were maintained in culture at 37 °C in RPMI-1640 medium (A549) or in DMEM medium (HT29), with 10% FBS in a humidified atmosphere of 5% CO2. Cell morphology was routinely checked. Confocal microscopy Cells were plated on labtek® and treated with 1 µmol.L -1 of IrL monomer 1 or Ir2L dimer 2 for 2 h, 4 h or 24 h in the dark at 37 °C before confocal imaging. Hoechst (5 µmol.L-1 ) was used to counterstain cell nuclei. Fluorescence microscopy was performed using a confocal microscope (LSM 710; Carl Zeiss, Jena, Germany). A 20× / 0.8 NA Plan Apochromat objective in air and a 63× / 1.4 NA Plan Apochromat objective in oil were used. Excitation was at 405 nm and the emission filter between 600 and 760 nm for the IrL monomer 1 and the Ir2L dimer 2 , and between 415 and 500 nm for Hoechst. [Fig.1] shows the photos obtained after 2 h, 4 h or 24 h with the IrL monomer 1 , for cells alone (left column), for the monomeric compound IrL 1 alone (middle column) and for cells and the monomeric compound IrL 1 simultaneously (right column). [Fig.2] shows the photos obtained after 2 h, 4 h or 24 h with the Ir2L dimer 2 , for cells alone (left column), for the dimeric compound Ir2L 2alone (middle column) and for cells and the dimeric compound Ir2L 2 simultaneously (right column). It is observed that the compounds according to the invention are localized in the cytoplasm of cancer cells. In vitro cytotoxicity tests Cell proliferation tests were carried out in 96-well culture plates for each of the following complexes: IrL monomer 1 , monomer H, monomer F and monomer Cl. Cells were cultured for 4 h and 24 h before treatment with increasing concentration of monomer in complete medium. Illumination at 420 nm with a power at 78.125 mW.cm −2 (16 s, fluence 1.2 J.cm −2 ; 2 min and 8 s, fluence 10 J.cm −2 and 5 min and 20 s, fluence 25 J. cm −2) (Lumidox® II 96-position LED Array, Analytical Sales and Services, Flanders, US) was performed 4 h or 24 h after treatment. Cell viability was quantified 72 h after light exposure with the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay (MTT assay). Cell viability was normalized to control cells (without drug and unilluminated). IrL monomer concentrations 1 , monomer H, monomer F and monomer Cl required to inhibit cell growth by 50% (IC50) were determined by interpolation from the dose-response curves. The results are reported in the following Table 1: [Table 1] Monomer Monomer Monomer Monomer Cell Lines Treatment Conditions 1 HF Cl IrL -1 -1 1 IC (nmol.L ) IC (nmol.L ) IC50 IC50 (nmol.L ) 50 50 -1 (nmol.L ) 58.0 ± 10.2 26.5 ± 9.1 167.8 ± Darkness 318 ± 22 12.4 62.7 ± 3.8 59.9 ± 88.7 ± 6.2 4 h -2 1.2 J.cm 150 ± 17 5.0 -2 A549 10 J.cm27 ± 3 12.2 ± 0.7 12.0 ± 0.8 16.9 ± 1.3-2 25 J.cm 3 ± 0 ndndndO bscurité 136 ± 6 ndndnd-2 1.2 J.cm 76 ± 6 ndndnd24 h -2 10 J.cm 25 ± 2 ndndnd-2 25 J.cm 6 ± 0 ndndndO bscurité 272 ± 18 ndndnd-2 1.2 J.cm 191 ± 23 ndndnd4 h -2 10 J.cm 34 ± 2 ndndnd-2 25 J.cm 15 ± 1 ndndnd HT29 O bscurité 208 ± 10 ndndnd-2 1.2 J.cm 112 ± 11 ndndnd24 h -2 10 J.cm 14 ± 1 ndndnd -2 25 J.cm 7 ± 0 ndndnd230.1 ± 12.6 178.6 ± 12.1 163.3 ± Darkness 256 ± 23 10.3 HeLa 4 h 72.5 ± 65.1 ± 2.1 74.7 ± 4.2 -2 1.2 J.cm 152 ± 17 1.7 -2 10 J.cm 15 ± 1 8.4 ± 0.3 5.5 ± 0.2 11.1 ± 0.3 -2 25 J.cm 1 ± 0 ndndndO bscurité 158 ± 16 ndndnd-2 1.2 J.cm 82 ± 9 ndndnd 24 h -2 10 J.cm 9 ± 1 ndndnd-2 25 J.cm 2 ± 0 ndndndnd not determined It is found that the concentrations of IrL monomer 1required to inhibit cell growth by 50% (IC50) are less than 191 nmol.L -1 at 1.2 J.cm −2 , regardless of the cell line considered, for a 4h or 24h culture, which makes this compound a particularly effective candidate for use in the treatment of cancer by dynamic phototherapy. It is found that the concentrations of monomer H, monomer F and monomer Cl required to inhibit cell growth by 50% (IC50) are less than 17 nmol.L -1 at 10 J.cm −2 , for the A549 cell line, and less than 12 nmol.L -1 at 10 J.cm −2 , for the HeLa cell line, making these compounds particularly effective candidates for use in the treatment of cancer by photodynamic therapy. The HT29 cell line is very sensitive and has not been tested with the monomer H, monomer F and monomer Cl complexes.

Claims

CLAIMS 1. Compound of general formula (I) or salt of this compound, formula in which - R 1 , R 2 , R 3 and R 4 are chosen independently of each other as being a hydrogen atom or a halogen atom; - R 5 is selected from a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group, a C2-C6-alkynyl group or a polyethylene glycol (PEG) group of the following formula: in which n is an integer ranging from 1 to 4; - L is chosen to be a single bond or linking group chosen from: - R 6 and R 7are independently selected from one another as being a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group or a C2-C6-alkynyl group, and - R 8 and R 11 are independently selected from a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group, a C2-C6-alkynyl group or a group of general formula (II) - R 9 and R 10 are independently chosen from each other as being a hydrogen atom or a C1-C6-alkoxy group, preferably a methoxy group, and wherein, if R 1 = R 2 = R 3 = R 4 = H and if L is a single bond, then R 8 is different from H.

2. Compound according to claim 1, characterized in that at least one substituent chosen from R 1 , R2 , R 3 and R 4 is a halogen atom.

3. Compound according to claim 2, characterized in that R 2 is a halogen atom.

4. Compound according to any one of claim 3, characterized in that R 1 , R 3 and R 4 are hydrogen atoms.

5. Compound according to claim 1, characterized in that R 1 , R 2 , R 3 and R 4 are hydrogen atoms.

6. Compound according to any one of claims 1 to 5, characterized in that R 5 is a C1-C6-alkyl group, preferably C1-C4-alkyl, more preferably a butyl group.

7. Compound according to any one of claims 1 to 6, characterized in that R 6 and R 7 are hydrogen atoms.

8. Compound according to any one of the preceding claims, characterized in that L is a single bond.

9. Compound according to claim 8, characterized in that R 8is a C1-C6-alkyl group, preferably a methyl group.

10. Compound according to claim 8, characterized in that R 8 is the compound of formula (II).

11. A process for preparing a compound according to any one of the preceding claims, comprising the following steps: - Suspending a compound of formula (III) in a mixture of CH2Cl2 / MeOH (1:1), - Addition of a compound of formula (IV) in which R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , and R 7 are as defined in one of claims 1 to 7, L is chosen as being a single bond or linking group chosen from: ; R 9 and R 10are chosen independently of each other as being a hydrogen atom or a C1-C6-alkoxy group, preferably a m group ethoxy, R 12 and R 13 are independently chosen from a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group, a C2-C6-alkynyl group or a group of general formula (V) in which R 1 , R 2 , R 3 , R 4 , R 5 , R 6 , and R 7 are as defined in any one of claims 1 to 7, - Refluxing overnight under argon, - Adding an excess of aqueous KPF6 (sat.).

12. Compound according to any one of claims 1 to 10 for use as a medicament.

13. Compound according to claim 12 for use in the treatment of cancer.

14. Compound of general formula (I): or salt of this compound, formula in which: - R 1 , R 2 , R 3 and R 4 are chosen independently of each other as being a hydrogen atom or a halogen atom; - R 5 is selected from a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group, a C2-C6-alkynyl group or a polyethylene glycol (PEG) group of the following formula: in which n is an integer ranging from 1 to 4; - L is chosen to be a single bond or linking group chosen from: ; - R 6 and R 7 are independently selected from one another as being a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group or a C2-C6-alkynyl group, and - R 8 and R 11are independently selected from a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group, a C2-C6-alkynyl group or a group of general formula (II) R 9 and R 10 are chosen independently of each other as being a hydrogen atom or a C1-C6-alkoxy group, preferably a methoxy group, for its use in the treatment of cancer by dynamic phototherapy.

15. Compound of general formula (I): or salt thereof, formula in which: -R1, R2, R3 and R4 are chosen independently of each other as being a hydrogen atom or a halogen atom; - R 5is selected from a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group, a C2-C6-alkynyl group or a polyethylene glycol (PEG) group of formula s uivante : in which n is an integer ranging from 1 to 4; - L is chosen to be a single bond or linking group chosen from: - R 6 and R 7 are independently selected from one another as being a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group or a C2-C6-alkynyl group, and - R 8 and R 11are independently selected from a hydrogen atom, a halogen atom, a C1-C6-alkyl group, a C1-C6-hydroxyalkyl group, a C1-C6-alkoxy group, a C2-C6-alkenyl group, a C2-C6-alkynyl group or a group of general formula (II) R 9 and R 10 are independently chosen from one another as being a hydrogen atom or a C1-C6-alkoxy group, preferably a methoxy group, for use in the treatment of antibiotic-resistant diseases.

16. Compound for use according to claim 14 or 15, characterized in that at least one substituent chosen from R 1 , R 2 , R 3 and R 4 is a halogen atom.

17. Compound for use according to claim 16, characterized in that R 2 is a halogen atom.

18. Compound for use according to claim 17, characterized in that R 1 , R 3 and R 4are hydrogen atoms.

19. Compound for use according to claim 14 or 15, characterized in that R 1 , R 2 , R 3 and R 4 are hydrogen atoms.

20. Compound for use according to any one of claims 14 to 19, characterized in that R 5 is a C1-C6-alkyl group, preferably C1-C4-alkyl, more preferably a butyl group.

21. Compound for use according to any one of claims 14 to 20, characterized in that R 6 and R 7 are hydrogen atoms.

22. Compound for use according to any one of claims 14 to 21, characterized in that L is a single bond.

23. Compound for use according to claim 22, characterized in that R 8 is a C1-C6-alkyl group, preferably a methyl group.

24. Compound for use according to claim 22, characterized in that R 8is the compound of formula (II).

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