Narrow Results

Lewis acid catalyzed condensation of pyrrole and 4-fluoro-2,6-dimethylbenzaldehyde followed by chemical oxidation afforded the corresponding chlorin along with the parent porphyrin. The subsequent metalation of the porphyrin-chlorin mixture in the presence of Zn(OAc)₂·2H₂O afforded Zn mono and di-hydroxychlorins in addition to the Zn porphyrin in a one-flask synthesis. This new direct hydroxylation reaction eliminates the need for highly toxic OsO₄ and H₂S that are traditionally used for the generation of hydroxy chlorins. In addition to the full characterization of the zinc chlorins, we present cyclic voltammograms, steady-state absorption, and emission profiles of this rarely available class of compounds. Our findings show that Zn mono- and di-hydroxychlorins are stable compounds that possess exceptionally long triplet excited states in solution, making them promising candidates for photodynamic therapy.

The synthesis of metallo derivatives (Ni, Zn) of phthalocyanines (pcs) obtained from 4,5-dicyanobenzomonoazacrown ether substituted with long alkyl chains (5a-d) are described. The new compounds have been characterized by elemental analysis, ¹H, ¹³C NMR, MS, IR and UV-vis spectroscopy techniques. The aggregation properties and alkali metal interaction of the pcs (6a-d and 7a-d) were investigated.

Pd(II), Co(II), Cu(II) and Zn(II) phthalocyanines with a tricarbethoxyethyl substituent on each benzo group were prepared from 4-(1,1,2-tricarbethoxyethyl)-phthalonitrile and the corresponding divalent metal salt at 170°C. Transesterification occurred when the reaction was carried out in pentanol. Treatment of the palladium complex with sodium ethoxide at room temperature and further acidification resulted with tetra(1,2-dicarboxyethyl)phthalocyaninatopal-ladium. Its UV-vis spectrum in aqueous solution indicated dimeric and monomeric species at pH ≈ 12, but at pH ≈ 6 only the dimeric form were present.

The synthesis of a phthalocyanine-porphyrin heteropentamer (zinc(II) tetra(5-phenoxy-10,15,20-triphenylporphyrin)) zinc(II) phthalocyanine, (ZnPc-(ZnTPP)₄), containing four units of zinc tetraphenylporphyrin linked to a central zinc phthalocyanine macrocycle via an ether linkage is reported. The photophysical parameters of the pentamer are reported in toluene and dimethyl sulfoxide (DMSO). The observed differences in the fluorescence behavior of the pentamer in the two solvents is explained in terms of emission from different states; charge transfer state in DMSO and locally excited state in toluene. The rate constants for fluorescence, intersystem crossing, internal conversion, and of charge and energy transfer are reported for the pentamer. Quantum yields for fluorescence, internal conversion, triplet state and of charge and energy transfer are also reported for the pentamer, ZnPc-(ZnTPP)₄ and the mixture of ZnPc and ZnTPP. The latter two parameters are higher in the pentamer compared to a mixture containing ZnPc and ZnTPP.

5,15-substituted porphyrins are valuable compounds in bioorganic and materials chemistry. A new synthesis has been developed that employs 1,9-diformylation of a dipyrromethane, conversion of the diformyldipyrromethane to the bis(imino) derivative, and reaction of the bis(imino)dipyrromethane + a dipyrromethane to give the zinc-porphyrin bearing trans-AB-substituents. 1,9-diformylation was achieved via Vilsmeier reaction. Imination was achieved by treatment of the 1,9-diformyldipyrromethane with excess amine under neat conditions at room temperature. The porphyrin-forming reaction was carried out over 2 h in refluxing ethanol containing zinc acetate exposed to air. Oxidation of the intermediate porphyrinogen occurs aerobically. A complex composed of two bis(imino)dipyrromethanes and two zinc atoms was observed to form reversibly during the course of the reaction. A set of zinc-porphyrins with trans-AB-, A₂-, or A-substituents has been prepared in yields of ~30% (without detectable scrambling) with straightforward purification. The reaction is applicable to A/B substituent combinations of aryl/aryl, aryl/alkyl, and aryl/H.

Magnesium porphyrazinate substituted with eight (1-naphthyl) groups on the peripheral positions has been synthesized by cyclotetramerization of 3,4-(1-naphthyl)pyrroline-2,5-diimine, 4-(1-naphthyl)pyrroline-2,5-diimine in the presence of magnesium butanolate. Its demetalation by treatment with trifluoroacetic acid, resulted in a partially oxidized product, namely, octakis(1-naphthyl)-2-seco-porphyrazine-2,3-dione. Further reaction of this product with copper(II) acetate, zinc(II) acetate and cobalt(II) acetate led to the metallo derivatives, [octakis(1-naphthyl)-2-seco-2,3-dioxoporphyrazinato]M(II) (M = Cu, Zn or Co). These new compounds have been characterized by elemental analysis, together with FT-IR, ¹H NMR, UV-vis and mass spectral data.

Metal-free and metallophthalocyanines with four 9-anthroyl groups bound through ethylthio ester bridges on the periphery have been prepared. The new compounds were characterized by elemental analyses, ¹H NMR, IR, mass and UV-vis spectral data. The electronic spectra exhibit an intense π-π* transition of 9-anthroyl identity together with characteristic Q and B bands of the phthalocyanine core. Effect of metal ions on intensity of fluorescence spectra of phthalocyanine derivatives substituted with 9-anthroyl groups was investigated. The energy transfer to the phthalocyanine core and radiative decays of the 9-anthroyl emission and phthalocyanine core were examined.

The synthesis, spectroscopic and electrochemical properties of new phthalocyanines bearing four morpholine and four chloro units is reported. Two-step synthesis involved efficient nucleophilic substitution of 4,5-dichlorophthalonitrile as the key step. The free-base phthalocyanine and its several complexes have been characterized using UV-vis, IR, ¹HNMR, ¹³CNMR and mass spectroscopic data. Voltammetric and spectroelectrochemical studies show that while cobalt phthalocyanine gives both metal- and ring-based, diffusion-controlled, multi-electron and reversible/quasi-reversible redox processes, other complexes give ring-based, multi-electron and reversible/quasi-reversible redox processes.

The synthesis, photophysical and photochemical properties of nonperipherally (α) mercaptoquinoline substituted Zn(II), TiO(IV) and Mg(II) and quaternized Zn(II) phthalocyanines are described for the first time. These complexes (2 to 5) and their precursor are characterized by elemental analysis, FT-IR, ¹H NMR, electronic spectroscopy as well as mass spectroscopy. Complexes 2, 4 and 5 have good solubility in organic solvents such as CHCl₃, DCM, DMSO, DMF, THF and toluene and are not aggregated in all solvents within a wide concentration range. Complex 3 showed very good solubility in water as well as DMSO and DMF. General trends are described for singlet oxygen, photodegradation and fluorescence quantum yields of these complexes in DMSO and DMF. While complex 2 has higher singlet oxygen and fluorescence quantum yields than 3, 4 and 5, complex 4 has higher fluorescence quantum yields in DMF and DMSO than 2, 3 and 5. The effect of the solvents and metal on the photophysical and photochemical parameters of the metallophthalocyanines are also reported.

The five possible non-peripherally substituted zinc(II) phthalocyanines with different molecular symmetries (Pc1–Pc5) were synthesized from statistical condensation of the phthalonitrile derivatives (A and B). 2-[2-(2-ethoxyethoxy)ethoxy]-1-[2-((2-ethoxyethoxy)-ethoxy)ethoxymethyl]ethyloxy and 2′-[(tert-butoxycarbonyl)amino]ethoxy groups were used as substituents. The structures of the new compounds were characterized using elemental analysis and spectroscopic data including IR, ¹H and ¹³C NMR, electronic absorption and mass spectra. The photophysical and photochemical properties of these new compounds were investigated in DMSO. The effect of the molecular symmetry of phthalocyanine molecules on the photophysical and photochemical properties was compared in this study.

This paper describes the preparation and spectral properties of a near-infrared fluorophore in which two bis(2-picolyl)amino moieties are axially linked to a silicon(IV) phthalocyanine core. The effects of various metal ions on its absorption and fluorescence spectra have been examined. The results indicate that this compound shows a high sensitivity and moderate selectivity toward Zn²⁺ ion.

We report here the preparation (in "one-pot") of a tetra-β″-sulfoleno-meso-aryl-porphyrin in about 80% yield by using an optimized modification of Lindsey's variant of the Adler–Longo approach. The Zn(II)-, Cu(II)- and Ni(II)-complexes of the symmetrical porphyrin were prepared and characterized spectroscopically. Crystal structures of the fluorescent Zn(II)- and of the non-fluorescent Ni(II)-tetra-β″-sulfoleno-meso-aryl-porphyrinates showed the highly substituted porphyrin ligands to be nearly perfectly planar. The Zn(II)-complex of this porphyrin has been used as a thermal precursor of a reactive diene, and — formally — of lateral and diagonal bis-dienes, of a tris-diene and of a tetra-diene, which all underwent [4 + 2]-cycloaddition reactions in situ with a range of dienophiles. Thus, the tetra-β″-sulfoleno-meso-aryl-porphyrin and its metal complexes represent reactive building blocks, "programmed" for the syntheses of symmetrical and highly functionalized porphyrins.

The novel zinc(II) phthalocyanine complexes bearing tetra or octa-[7-oxy-3-(3′,4′,5′-trimethoxyphenyl)coumarin] moieties were synthesized for the first time in this study. These phthalocyanines were characterized by different spectroscopic methods such as FT-IR, ¹H NMR, electronic absorption spectra, MALDI-TOF mass and elemental analyses as well. The photochemical properties such as singlet oxygen generation, photostability and photophysical properties such as fluorescence quantum yields and lifetimes were investigated in $N$,$N$-dimethylformamide (DMF) solutions. The effect of the structure (the position and number of the coumarin groups on phthalocyanine framework) of novel phthalocyanines on these properties was also determined in this study.

Using a hydrothermal reaction of SmCl₃•6H₂O, ZnBr₂ and TPPS, a crystalline metalloporphyrinic compound (MPC), [SmZn(TPPS)H₃O]${}_n$•2$n$H₂O (1), was synthesized. The crystal structure of the MPC exhibits a condensed and robust 3-D porous open framework. We studied the adsorption and desorption isotherms for N₂, H₂ and CO₂ conducted at 77 K and 273 K. They show different isotherms such as Type I, II and III isotherm behaviors. We found that low temperature is propitious for the title complex to adsorb more H₂, but less N₂. Compound 1 showed remarkably high selectivity for CO₂–N₂ separation, and good thermal stability. The temperature dependent magnetic susceptibility shows an antiferromagnetic-like behavior for 1.

“Non-fluorescent” chlorophyll catabolites (NCCs) were named “rusty pigments” originally, as they easily oxidized to yellow chlorophyll catabolites (YCCs) and other colored natural “phyllobilins.” In the present work, binding of Zn(II)-ions by YCC and its methyl ester YCC-Me, and structural investigations of the resulting Zn(II)-complexes are reported. Binding of Zn-ions to the weakly luminescent YCC or YCC-Me in DMSO produces orange-yellow complexes that exhibit strong green emission. The Zn-complex of YCC-Me was isolated and characterized by UV-vis-, fluorescence-, mass- and NMR-spectra. The data revealed a 2:1 complex, Zn(YCC-Me)${}_2$, in which YCC-Me serves as bidentate ligand. The Zn(II)-center in Zn(YCC-Me)${}_2$ is, thereby, deduced to be coordinated in a pseudo tetrahedral fashion. Formation of Zn(YCC-Me)${}_2$ (and of Zn(YCC)${}_2)$ is compatible with an isomerization of the lactam form of ring D to the corresponding lactim tautomer in these neutral Zn(II)-complexes.

Tetra and octa substituted novel zinc(II) phthalocyanines (3a and 5a) bearing carbazole groups were synthesized by cyclotetramerization of respective phthalonitrile derivatives (3 and 5). The zinc(II) phthalocyanines (3a and 5a) were converted into the water-soluble quaternized derivatives (3b and 5b) by utilizing dimethylsulphate as quaternizing agent. The synthesized novel compounds were confirmed thruogh FT-IR, UV-vis and MALDI-TOF mass spectroscopic data and elemental analysis as well. The photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation) properties of new phthalocyanines were determined in dimethylsulfoxide (DMSO). The photophysical and photochemical results were compared according to the number of the carbazole groups on the phthalocyanine core. Additionaly, in vitro photocytotoxicity of the targeted compounds were examined against to hepato cellular carcinoma (HuH-7) cancer cell line for determination of their photosensitizing ability.

We attempted the calculation of an accurate equilibrium constant for the dimerization process of enantiomerically pure Zn-1 using UV-vis dilution experiments. At millimolar concentration Zn-1 is involved in a chemical exchange process between its monomeric and dimeric state that is slow on the ¹H NMR timescale. We performed variable-temperature ¹H NMR experiments in CDCl₃ solution to determine the dimerization constant value at different temperatures and performed a van’t Hoff plot to derive the thermodynamic parameters of the process. The calculated thermodynamic data revealed that the dimerization process is entropy-driven and enthalpically opposed. We also probed the coordination of quinuclidine, 1-azabicyclo[2.2.2]octane, 2, to the Zn-1 using UV-vis and ¹H NMR titrations in CDCl₃ solution. At micromolar concentration the Zn-1 exclusively exists in solution as a monomer and forms a simple 1:1, $2\cdot Zn-1$, complex with quinuclidine having a stability constant of $K$($2\cdot Zn-1$) $=$ 10⁶ M${}^{-1}$. On the other hand, the ¹H NMR titrations carried out at 298 K and at millimolar concentration showed that Zn-1 was present in solution as the dimer and formed 1:2, $2\cdot {[Zn-1]}_2$, and 2:2, $2_2\cdot {[Zn-1]}_2,$ complexes by coordination to 2. In addition, the 1:1 complex, $2\cdot Zn-1$ showed a reduced dimerization constant compared to the uncoordinated parent monomer Zn-1. At high quinuclidine concentration, the 1:1 complex, $2\cdot Zn-1$, derived from the coordinated dimer dissociation was also detected. The ¹H NMR spectra of the titrations displayed separate signals for some hydrogen atoms of the Zn-phthalocyanine in each one of the four species. Remarkably, the chemical exchange processes involving free and bound quinuclidine in the monomeric and dimeric complexes showed different kinetics on the NMR timescale.

The first 5,10,15,20-tetra-(4-(triazol-1-yl)phenyl) porphyridine complex, [Zn${}_{\mathrm{\text{2}}}$Cl${}_{\mathrm{\text{4}}}$(5,10,15,20-tetra-(4-(triazol-1-yl)phenyl)porphyridine)]${}_{n}n$Cl•$n$H${}_{\mathrm{\text{3}}}$O•7$n$H${}_{\mathrm{\text{2}}}$O (1) has been synthesized via solvothermal reactions and characterized by single-crystal X-ray diffraction. Complex 1 is characteristic of a one-dimensional (1-D) structure, consisting of neutral [Zn${}_{\mathrm{\text{2}}}$Cl${}_{\mathrm{\text{4}}}$(5,10,15,20-tetra-(4-(triazol-1-yl)phenyl) porphyridine)]${}_n$ chains, isolated chloride ions and lattice water molecules. The zinc ion is in a four-coordinated tetrahedral geometry, and the porphyrin macrocycle is saddle-distorted. Photoluminescence measurement with solid-state samples discovers that it exhibits an emission in the green region of the light spectrum. Time-dependent density functional theory (TDDFT) calculation discovers that this emission can be attributed to the $\pi$–$\pi$* charge transfer. The cyclic voltammetry (CV) measurement reveals that it possesses an oxidation peak at 0.37 V.

In this study, ethyl 7-hydroxy-6-chloro-4-methylcoumarin-3-propanoate (1), ethyl 7-(2,3-dicyanophenoxy)-6-chloro-4-methylcoumarin-3-propanoate (2), ethyl 7-(3,4-dicyanophenoxy)-6-chloro-4-methylcoumarin-3-propanoate (3), ethyl 4-chloro-5-(7-oxy-6-chloro-4-methylcoumarin-3-propanoate)phthalonitrile (4) were synthesized. The phthalonitrile derivatives (2, 3 and 4) were converted to their peripheral tetra, non-peripheral tetra and peripheral chlorocta substituted zinc(II) and chloroindium phthalocyanine derivatives. All novel compounds were characterized by elemental analysis, FT-IR, ${}^{\mathrm{\text{1}}}$H-NMR, MALDI-TOF mass spectrometry and UV-vis spectral data. Additionally, the spectral, photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation and photodegradation under light irradiation) properties of the resulting substituted phthalocyaninatozinc(II) and indium(III) chloride complexes (5–10) were investigated in DMF, and the obtained results were compared for determination of the effects of the substituents’ positions and the variety of the central metal atom on these properties. The fluorescence quenching behavior of these phthalocyanines (5–10) were also investigated using 1,4-benzoquinone as a quencher. The obtained ethyl 7-oxy-6-chloro-4-methylcoumarin-3-propanoate bearing phthalocyaninatozinc(II) (5, 7 and 9) and indium(III) chloride (6, 8 and 10) complexes showed excellent solubility in most organic solvents. They produced high singlet-oxygen and showed appropriate photodegradation which is very important for photodynamic therapy applications.

The infrared spectra of tetrakis(dibutylamino) phthalocyanine and octakis(dibutylamino) compounds were studied via theoretical investigations. The results reveal deep fusion of the peripheral alkylamino moieties with the phthalocyanine chromophore in the tetrakis(dibutylamino)- but not in the octakis(dibutylamino)-phthalocyanine compounds. The successive localized molecular orbitals (LMO) and bond order analyses give support for the infrared vibrational results.