Novel sulfonated hydrophilic indium(III) and gallium(III) phthalocyanine photosensitizers: preparation and investigation of photophysicochemical properties

The new tetra-non-peripherally benzenesulfonic acid-substituted hydrophilic gallium chloride and indium chloride phthalocyanine complexes have been synthesized by cyclotetramerization of 4-(2,3-dicyanophenyl)benzenesulfonic acid (1). The newly synthesized phthalocyanines have been characterized by Fourier transform infrared spectroscopy, proton nuclear magnetic resonance, mass and UV–vis spectroscopy techniques. The water-soluble gallium(III) phthalocyanine derivative (2) was aggregated in aqueous media but was fully disaggregated in the presence of a surfactant Triton X-100. The incorporation of sulfonate moieties of the phthalocyanine macrocycle provides hydrophilic character to the new compounds, which is useful for drug administration and serves as crucial in PDT application. So, the photochemical properties (singlet oxygen quantum yields and photodegradation quantum yields) and photophysical properties (fluorescence behavior) of the complexes were reported in different solutions (DMSO and water). The results of spectral measurements showed that both np-GaPc (2) and np-InPc (3) can be used as sensitizers in PDT because of their singlet oxygen efficiencies.     

Syntheses, electrochemical and spectroelectrochemical properties of novel ball-type and mononuclear Co(II) phthalocyanines substituted at the peripheral and non-peripheral positions with binaphthol groups

Mononuclear cobalt phthalocyanine (CoPc) substituted at the non-peripheral 8 and peripheral positions 9 with 1,1′-binaphthyl-8,8′-diol and ball-type dinuclear Co₂Pc₂ substituted at the non-peripheral 10 and peripheral 11 positions with the same substituent are reported. The complexes with 1,1′-binaphthol-bridges were prepared from the corresponding phthalonitriles 4-7. The effects of the position of substituent on spectral, electrochemical and spectroelectrochemical properties of these complexes were also explored. The mononuclear complexes 8 and 9 exhibited one metal reduction, one ring reduction and one ring oxidation. The redox properties of the ball-type complexes 10 and 11 exhibited two reduction processes assigned to [(Co^IPc⁻²)₂]²⁻/[(Co^IPc⁻³)₂]⁴⁻ (I), (Co^IIPc⁻²)₂/[(Co^IPc⁻²)₂]²⁻ (II) and one oxidation process assigned to [(Co^IIIPc⁻²)₂]²⁺/Co^IIPc⁻²)₂ (III). The ball-type complexes are much easier to oxidize and more difficult to reduce than the corresponding monomers 8 and 9.     

Synthesis and reactivity of substituted cyclopentadienyl rhodium(I) and (III) complexes

New cyclopentadienyl derivatives of rhodium COD complexes [Cp*=C₅H₄COOCH₂CHCH₂ (1); C₅H₄CH₂CH₂CHCH₂ (2); C₅H(i-C₃H₇)₄ (3)] and carbonyl complex [Cp*=C₅H(i-C₃H₇)₄ (4)] were synthesized from [RhCl(COD)]₂ and [RhCl(CO)₂]₂. 1, 2 and 3 oxidized by iodine gave iodine bridged dimers 5, 6 and 7, respectively. Triphenyl phosphine, carbon monoxide and carbon disulfide molecules broke down the iodine bridged structure easily and produced monomer products Cp*RhI₂L [Cp*=C₅H₄COOCH₂CHCH₂, L=CS₂ (8); L=PPh₃ (9). Cp*=C₅H(i-C₃H₇)₄, L=CO (10)]. All of these new compounds were characterized by elemental analysis, ¹H NMR, IR, UV-Vis and mass spectroscopy. The crystal structure of 1 was solved in the triclinic space group with one molecule in the unit cell, the dimensions of which are a=7.082(9) Å, b=8.392(3) Å, c=13.889(5) Å, α=101.19(3)°, β=99.06(6)°, γ=105.11(5)°, and V=763(1) ų. The crystal structure of 3 was solved in the orthorhombic space group Pn21a with four molecules in the unit cell, the dimensions of which are a=9.748(3) Å, b=16.054(5) Å, and V=2319(1) ų. Least squares refinement leads to values for the conventional R₁ of 0.0251 for 1 and 0.0558 for 3, respectively. Compared to that in 1, a shorter metal-ligand bond length in 3 was observed and this is attributed to the rich electron density on Rh(I) metal center piled up by the C₅H(i-C₃H₇)₄ ligand.     

Synthesis and phosphorescent properties of two novel iridium (Ⅲ) complexes bearing bulky tert-butyl substituents

The synthesis and phosphorescence properties of two novel Ir(Ⅲ)complexes bearing tert-butyl substituents,bis(4-tert-butyl-2- phenylbenzothiozolato-N,C~(2′))iridium(Ⅲ)(acetylacetonate)[(tbt)_2Ir(acac)]and bis(4-tert-butyl-1-phenyl-1H-benzimidazolato- N,C~(2′))iridium(Ⅲ)(acetylacetonate)[(tpbi)_2Ir(acac)],are reported,their molecular structures are confirmed by~1H NMR,ESI-MS and elementary analysis.Photoluminescence(PL)studies revealed that they can emit strong green and orange phosphorescence in high quantum yields.Compared to their prototypes lacking of tert-butyl substituents,the two novel iridium(Ⅲ)complexes both have shorter lifetimes and improved or nearly similar PL quantum efficiencies,implying that the exciton quenching is inhibited effectively when molecular steric hindrance increases.The two chelates have great potential to be used as electrophosphorescent materials.     

Synthesis and characterization of half-sandwich iridium(III) and rhodium(III) complexes bearing organochalcogen ligands

Reactions of [Cp*M(μ-Cl)Cl]₂ (M = Ir, Rh; Cp* = η⁵-pentamethylcyclopentadienyl) with bi- or tri-dentate organochalcogen ligands Mbit (L1), Mbpit (L2), Mbbit (L3) and [Tm^Me]⁻ (L4) (Mbit = 1,1′-methylenebis(3-methyl-imidazole-2-thione); Mbpit = 1,1′-methylene bis (3-iso-propyl-imidazole-2-thione), Mbbit = 1,1′-methylene bis (3-tert-butyl-imidazole-2-thione)) and [Tm^Me]⁻ (Tm^Me = tris (2-mercapto-1-methylimidazolyl) borate) result in the formation of the 18-electron half-sandwich complexes [Cp*M(Mbit)Cl]Cl (M = Ir, 1a; M = Rh, 1b), [Cp*M(Mbpit)Cl]Cl (M = Ir, 2a; M = Rh, 2b), [Cp*M(Mbbit)Cl]Cl (M = Ir, 3a; M = Rh, 3b) and [Cp*M(Tm^Me)]Cl (M = Ir, 4a; M = Rh, 4b), respectively. All complexes have been characterized by elemental analysis, NMR and IR spectra. The molecular structures of 1a, 2b and 4a have been determined by X-ray crystallography.     

The encapsulation of Rh(III) phthalocyanines in zeolites X and Y

The template syntheses of rhodium(III) phthalocyanine complexes within the supercage structures of zeolites X and Y are reported. These ship-in-a-bottle compounds are characterized by elemental analysis, UV-Vis, IR, XRD and X-ray photoelectron spectroscopy. The effect of temperature on the encapsulation process is also discussed.     

Synthesis and DNA-binding properties of apoptosis-inducing cytotoxic half-sandwich rhodium(III) complexes with methyl-substituted polypyridyl ligands

Half-sandwich organorhodium(III) complexes of the type [(η⁵-C₅Me₅)RhCl(pp)] (CF₃SO₃) containing polypyridyl ligands (pp) represent a promising class of cytostatic agents. Replacement of the polypyridyl ligands of complexes 1 (pp = phen) and 6 (pp = dppz) by methyl-substituted derivatives in 2-5 (pp = 4-Mephen, 5-Mephen, 4,7-Me₂phen, 5,6-Me₂phen) and 7 (pp = Me₂dppz) leads to a significant improvement in their antiproliferative activity towards human MCF-7 and HT-29 cancer cells. For instance, the IC₅₀ value towards HT-29 cells decreases from 4.3 ± 0.2 μM for 6 to 0.98 ± 0.49 μM for complex 7. In contrast, no activity (IC₅₀ > 100 μM) was observed for the HOOC and n-BuNHCO substituted dppz complexes 8 and 9. UV/vis, CD and NMR spectra for mixtures of complexes 7-9 with CT DNA were in accordance with intercalation of the substituted dppz ligands between the base pairs of the double helix and direct evidence for this binding mode was also provided by a 2D NOESY study for complex 7 with the hexanucleotide d(5′-CGTCGG-3′). Each of the methyl-substituted phen complexes 2-5 is significantly more active towards immortalized HEK-293 cells (IC₅₀ values 0.40 ± 0.02 to 0.94 ± 0.02 μM) than towards the cancer cells. Flow cytometric measurements of DNA fragmentation in BJAB cells following an incubation period of 72 h with 1, 5 and 6 indicate that the complexes induce specific apoptotic cell death in the non-adherent lymphoma cells.     

Synthesis and properties of new binuclear nickel(ii) phthalocyanines

New binuclear nickel(ii) phthalonitrile complexes, viz., Ni^II 2,2",9(10),9"(10"),17(18),17"(18"),24(25),24"(25")-tetra(phenylene-1,2-dioxy)bisphthalocyanine and Ni^II 2,2",9(10),9"(10"),17(18),17"(18"),24(25),24"(25")-tetra(4-tert-butylphenylene-1,2-dioxy)bisphthalocyanine, were synthesized. The complexes were characterized by electronic spectroscopy and MALDI—TOF mass spectrometry and studied as active components for membranes of ion-selective electrodes in solutions of dicarboxylic acids.     

Iridium (III) and rhodium (III) triazoles by 1,3-dipolar cycloadditons to a coordinated azide in iridium (III) and rhodium (III) compounds

The reaction of [(η⁵-C₅Me₅)M(μCl)Cl]₂ with the ligand (L^∩L) in the presence of sodium methoxide yielded compounds of general formula [(η⁵-C₅Me₅)M(L^∩L)Cl] (1–10) (where M = Ir or Rh and L^∩L = N^∩O or O^∩O chelate ligands). Azido complexes of formulation [(η⁵-C₅Me₅)M(L^∩L)N₃] (11–20) have been prepared by the reaction of [(η⁵-C₅Me₅)M(μN₃)(X)]₂ (X = Cl or N₃) with the corresponding ligands or by the direct reaction of [(η⁵-C₅Me₅)M(L^∩L)Cl] with NaN₃. These azido complexes [(η⁵-C₅Me₅)M(L^∩L)N₃] undergo 1,3-dipolar cycloaddition reaction with substituted alkynes in CH₂Cl₂ and for the first time in ethanol at room temperature to yield iridium (III) and rhodium (III) triazoles (21–28). The compounds were characterized on the basis of spectroscopic data, and the molecular structures of 2 and 26 have been established by single crystal X-ray diffraction.     

Synthesis and photophysical properties of lead phthalocyanines

This work reports on the synthesis and photophysical parameters of tetra-and octa-substituted new lead phthalocyanines. The complexes synthesized are: 1,4-(tetraphenoxyphthalocyaninato)lead (7a), 1,4-(tetra-tert-butylphenoxyphthalocyaninato)lead (7b), 2,3-(tetraphenoxyphthalocyaninato)lead (8a), 2,3-(tetra-tert-butylphenoxyphthalocyaninato)lead (8b), 2,3-octaphenoxyphthalocyaninatolead (9a) 2,3-[octakis(4-t-butylphenoxyphthalocyaninato)]lead (9b). Photophysical properties were studied for these complexes in a dimethylsulfoxide, dimethylformamide, toluene, tetrahydrofuran and chloroform. The fluorescence spectra were different from excitation spectra due to demetallation upon excitation. High triplet quantum yields ranging from 0.70 to 0.88 (in DMSO, DMF and toluene) and low triplet lifetimes (20–50 μs in DMSO, and <10 μs in the rest of the solvents) were observed due to the presence of heavy atom.     

Aqueous rhodium(III) hydrides and mononuclear rhodium(II) complexes

In aqueous solutions, as in organic solvents, rhodium hydrides display the chemistry of one of the three limiting forms, i.e. {Rh(I)+ H+}, {Rh(II)+ H.}, and {Rh(III)+ H-}. A number of intermediates and oxidation states have been generated and explored in kinetic and mechanistic studies. Monomeric macrocyclic rhodium(II) complexes, such as L(H2O)Rh2+ (L = L1 = [14]aneN4, or L2 = meso-Me6[14]aneN4) can be generated from the hydride precursors by photochemical means or in reactions with hydrogen atom abstracting agents. These rhodium(II) complexes are oxidized rapidly with alkyl hydroperoxides to give alkylrhodium(III) complexes. Reactions of Rh(II) with organic and inorganic radicals and with molecular oxygen are fast and produce long-lived intermediates, such as alkyl, superoxo and hydroperoxo complexes, all of which display rich and complex chemistry of their own. In alkaline solutions of rhodium hydrides, the existence of Rh(I) complexes is implied by rapid hydrogen exchange between the hydride and solvent water. The acidity of the hydrides is too low, however, to allow the build-up of observable quantities of Rh(I). Deuterium kinetic isotope effects for hydride transfer to a macrocyclic Cr(v) complex are comparable to those for hydrogen atom transfer to various substrates.     

Synthesis and Photophysical Properties of Hetero‐Bischelated Complexes of Rhodium(III) Containing Phenyl‐Pyridin‐2‐Ylmethylene‐Amine

Three new hetero‐bischelated rhodium (III) complexes of cis‐[Rh(PA)(L)Cl₂]Cl (where PA = phenylpyridin‐2‐ylmethylene‐amine; L = 2,2′‐bipyridine, 2,2′‐dipyridylamine and 1,10‐phenanthroline) have been successfully prepared and characterized. Each complex shows high intensity bands in the UV region, and these are assigned to spin‐allowed π‐π* transitions. The medium‐intensity absorption band profile in the lower energy region can be explained by convolution of spin‐allowed CT and d‐d* transitions. The emission spectra at low temperature (77 K) of these complexes in EtOH/MeOH (4:1 v/v) are virtually identical. They all exhibit a broad, symmetric, and structureless red emission with a microsecond lifetime and hence are assigned as the d‐d* phosphorescence.     

Reduction of rhodium(III) trifluoroacetate by norbornadiene

It was shown that the action of heat on rhodium(III) trifluoroacetate with norbornadiene (NBD) leads to its reduction and the formation of red crystals of [Rh(CF₃COO)NBD]₂. The formation of the complex was confirmed by elemental analysis and IR, electronic, and x-ray photoelectron spectra. The reaction shows that Rh-Rh compounds can disproportionate under the influence of NBD with the formation of Rh(I) and Rh(III).Institute of Chemical Physics at Chernogolovka, Russian Academy of Sciences, 142432 Chernogolovka. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 6, pp. 1438–1440, June, 1992.     

Synthesis and photophysical properties of annulated dinuclear and trinuclear phthalocyanines

Metal-free mononuclear, dinuclear and trinuclear phthalocyanines were prepared by a mixed cyclotetramerisation of a 1,2,4,5-tetracyanobenzene derivative and 4,5-bis(2,6-dimethylphenoxy)phthalonitrile. For the first time, a pi-electron-conjugated trinuclear phthalocyanine was synthesised with phthalocyanine units connected by common annulated benzene rings. The Q band of the trinuclear compound in solution occurs at lambda = 944 nm whereas those of the dinuclear and mononuclear compounds are at lambda = 853/830 and 701/664 nm, respectively. Fluorescence quantum yields, fluorescence lifetimes and singlet-oxygen quantum yields of the compounds were determined.     

Synthesis of tetrathiafulvalene-annulated phthalocyanines

The synthesis of three new TTF-annulated phthalocyanine (Pc) derivatives 5a-c are described. All of them have been characterized by elemental analysis, IR and UV-vis spectroscopy. In all cases, the incorporation of long and flexible aliphatic side-chains into the rigid TTF-annulated Pc core did not promote the formation of a discotic mesophase.     

Synthesis and spectroscopic properties of new water-soluble phthalocyanines containing pyridinium hydrochloride fragments

New 2,9,16,23-tetra[o-(hydroxymethyl)benzyloxy]-substituted phthalocyanines were synthesized. Their reaction with 4-bromopyridine afforded 2,9,16,23-tetra[o-(4-pyridyloxymethyl)benzyloxy]-substituted analogs, treatment of which with HCl led to water-soluble pyridinium salts. Spectroscopic properties of the phthalocyanines obtained were studied and a hypsochromic shift of the Q-band of the hydrochloride as compared with the corresponding pyridinium analogs was observed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2350–2354, December, 2007.     

Iridium(III) and rhodium(III) cyclometalated complexes containing sulfur and selenium donor ligands

Treatment of [M(Buppy)₂Cl]₂ (M=Ir (1), Rh (2); BuppyH=2-(4^′-tert-butylphenyl)pyridine) with Na(Et₂NCS₂), K[S₂P(OMe)₂], and K[N(Ph₂PS)₂]₂ afforded monomeric [Ir(Buppy)₂(S^∧S)] (S^∧S=Et₂NCS₂ (3), S₂P(OMe)₂ (4), N(PPh₂S)₂ (5)) and [Rh(Buppy)₂(S^∧S)] (S^∧S=Et₂NCS₂ (6), S₂P(OMe)₂ (7), N(PPh₂S)₂ (8)), respectively. Reaction of 1 with Na[N(PPh₂Se)₂] gave [Ir(Buppy)₂{N(PPh₂Se)₂}] (9). The crystal structures of 3, 4, 7, and 8 have been determined. Treatment of 1 or 2 with AgOTf (OTf=triflate) followed by reaction with KSCN gave dinuclear [{M(Buppy)₂}₂(μ-SCN)₂] (M=Ir (10), Rh (11)), in which the SCN⁻ ligands bind to the two metal centers in a μ-S,N fashion. Interaction of 1 and 2 with [Et₄N]₂[WQ₄] gave trinuclear heterometallic complexes [{Ir(Buppy)₂}₂(μ-WQ₄)] (Q=S (12), Se (13)) and [{Rh(Buppy)₂}₂{(μ-WQ)₄}] (Q=S (14), Se (15)), respectively. Hydrolysis of 12 led to formation of [{Ir(Buppy)₂}₂{W(O)(μ-S)₂(μ₃-S)}] (16) that has been characterized by X-ray diffraction.     

Synthesis and electronic spectra of dimeric phthalocyanines

Dimeric phthalocyanines of a new type with a bridging 9,9,10,10-tetramethyl-9,10-dihydroanthracene fragment were synthesized. On the basis of X-ray diffraction analysis and molecular modeling of 9,9,10,10-tetramethyl-9,10-dihydroanthracene, a nearly planar structure was assumed for these phthalocyanines. The electronic absorption spectra of the obtained phthalocyanines and their monomeric and conjugated dimeric analogs were compared. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1686–1692, October, 2006.     

Synthesis and Pd(II) binding studies of octasubstituted alkyl thio derivatised phthalocyanines

Synthesis and characterization of non-peripherally (4,5) and peripherally (6,7) substituted metal free and Pd octapentylthiophthalocyanine and coordination of palladium ions to these Pcs are reported. The unmetalated complexes (4 and 6) show Pd coordination at the central metal and at the ring. The number of Pd ions bound to complex 4 were found to be five and to complex 6 were three. The equilibrium constant for the binding of Pd to complexes 4 was lower (K = 1.2 × 10⁹ dm³ mol⁻¹) than for complex 6 (K = 5.7 × 10¹⁰ dm³ mol⁻¹).     

Synthesis and catalytic properties of N -functionalised carbene complexes of rhodium(I)

Reaction of [RhCl(COD)]₂, with 1,3-dialkylimidazolinylidene (1) or 1,3-dialkylbenzimidazolinylidene (2) resulted in the formation of rhodium(I) 1,3-dialkylimidazolin-2-ylidene (3a-c) and 1,3-dialkylbenzimidazolin-2-ylidene (4a,b) complexes. Triethylsilane reacts with acetophenone derivatives in the presence of catalytic amounts of RhCl(COD)(1,3-dialkylimidazolin-2-ylidene) or RhCl(COD)(1,3-dialkylbenzimidazolin-2-ylidene) to give the corresponding silylethers in good yield (57–98%).