Porphyrin

The specific spectroscopic and redox properties of porphyrins predestine them to fulfill the role of sensors during interacting with different biologically active substances. Monitoring of binding interactions in the systems porphyrin-biologically active compound is a key question not only in the field of physiological functions of living organisms, but also in environmental protection, notably in the light of the rapidly growing drug consumption and concurrently the production of drug effluents. Not always beneficial action of drugs on natural porphyrin systems induces to further studies, with commercially available porphyrins as the model systems...

OBJECTIVES: Photodynamic therapy (PDT) is an effective cancer treatment that uses photosensitizers, light, and oxygen to destroy malignant cells. Porphyrins, and in particular the cationic derivatives, are the most investigated photosensitizers for PDT. In this context, it is important to study new methodologies to develop efficient cationic photosensitizers for use in PDT. MATERIALS AND METHODS: New porphyrins bearing cationic epoxymethylaryl groups were synthesized and characterized...

Porphyrins are conjugated, stable chromophores with a central core that binds a variety of metal ions and an easily functionalized peripheral framework. By combining the catalytic, electronic or cytotoxic properties of selected transition metal complexes with the binding and electronic properties of porphyrins, enhanced characteristics of the ensemble are generated. This review article focuses on porphyrins bearing one or more peripheral transition metal complexes and discusses their potential applications in catalysis or biomedicine...

Molecular functionalization of porphyrins opens countless new opportunities in tailoring their physicochemical properties for light-harvesting applications. However, the immense materials space spanned by a vast number of substituent ligands and chelating metal ions prohibits high-throughput screening of combinatorial libraries. In this work, machine learning algorithms equipped with the domain knowledge of chemical graph theory were employed for predicting the energy gaps of >12000 porphyrins from the Computational Materials Repository...

A combined theoretical and experimental approach has been used to investigate the binding energy of a ruthenium metalloporphyrin ligated with CO, ruthenium tetraphenylporphyrin [RuII TPP], in the RuII oxidation degree. Measurements performed with VUV ionization using the DESIRS beamline at Synchrotron SOLEIL led to adiabatic ionization energies of [RuII TPP] and its complex with CO, [RuII TPP-CO], of 6.48 ± 0.03 eV and 6.60 ± 0.03 eV, respectively, while the ion dissociation threshold of [RuII TPP-CO]+ is measured to be 8...

The precise tuning of local spin states in adsorbed organometallic molecules by a mechanically controlled scanning tunneling microscope (STM) tip has become a focus of recent experiments. However, the underlying mechanisms remain somewhat unclear. We investigate theoretically the STM-tip control of local spin states in a single iron(II) porphyrin molecule adsorbed on the Pb(111) substrate. A combined density functional theory and hierarchical equations of motion approach is employed to simulate the tip tuning process, in conjunction with the complete active space self-consistent field method for an accurate computation of magnetic anisotropy...

BACKGROUND: The aim of this study was to assess antimicrobial efficacy and cytotoxic outcomes of a chlorophyll based photosensitizer (PS) Zn(II)chlorin e6 methyl ester (Zn(II)e6 Me), when applied to human dentin discs and root blocks infected with 48 h biofilms. The results were compared with the ones obtained with FotoSan® (commercial Toluidine Blue O formulation) and 3% sodium hypochlorite (NaOCl). METHODOLOGY: Dentin and root blocks were infected with mixed biofilms of Enterococcus faecalis and Candida albicans; exposed for 15 min to 0...

To elucidate the regularities inherent in the kinetics of ultrafast charge recombination following photoinduced charge separation in donor-acceptor dyads in solutions, the simulations of the kinetics have been performed within the stochastic multichannel point-transition model. Increasing the solvent relaxation time scales has been shown to strongly vary the dependence of the charge recombination rate constant on the free energy gap. In slow relaxing solvents the non-equilibrium charge recombination occurring in parallel with solvent relaxation is very effective so that the charge recombination terminates at the non-equilibrium stage...

One of the most important chemical reactions for renewable energy technologies such as fuel cells and metal-air batteries today is oxygen reduction. Due to the relatively sluggish reaction kinetics, catalysts are necessary to generate high power output. The most common catalyst for this reaction is platinum, but its scarcity and derived high price have raised the search for abundant nonprecious metal catalysts. Inspired from enzymatic processes which are known to catalyze oxygen reduction reaction efficiently, employing transition metal complexes as their catalytic centers, many are working on the development of bioinspired and biomimetic catalysts of this class...

In this work, a highly sensitive photoelectrochemical (PEC) assay was constructed based on a donor-acceptor (D-A)-type material poly{4,8-bis[5-(2-ethylhexyl) thiophen-2-yl]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl-alt-3-fluoro-2-[(2-ethylhexyl)-carbonyl]thieno[3,4-b]thiophene-4,6-diyl} (PTB7-Th) as photoactive material and polyaniline (PANI) in-situ deposited on the surface of PTB7-Th as signal enhancer. Initially, PTB7-Th that contains an electron-rich unit as donor and an electron-deficient unit as acceptor with the easy separation of electron-hole pairs and intermolecular electron transfer provided an excellent photocurrent response...

The new Beckman Coulter Optima AUC instrument, which features multi-wavelength detection that couples the hydrodynamic separation of colloidal mixtures to spectral deconvolution of interacting and non-interacting solutes present in a mixture, was used to analyze the composition of human serum albumin (HSA) bound to metallo-protoporphyrin. We present new methods implemented in UltraScan that permit Optima AUC-derived multi-wavelength data to be spectrally decomposed in the same fashion as has been made possible for the Cölfen detector earlier...

The role of peroxometal species as reactive intermediates in myriad biological processes has motivated the synthesis and study of analogous molecular model complexes. Peroxomanganese(iv) porphyrin complexes are of particular interest, owing to their potential ability to form from reversible O2 binding, yet have been exceedingly difficult to isolate and characterize in molecular form. Alternatively, immobilization of metalloporphyrin sites within a metal-organic framework (MOF) can enable the study of interactions between low-coordinate metal centers and gaseous substrates, without interference from bimolecular reactions and axial ligation by solvent molecules...

The non-innocent ligand nature of porphyrins was observed for compound I in enzymatic cycles of cytochrome P450. Such porphyrin radicals were first regarded as reactive intermediates in catabolism, but recent studies have revealed that porphyrinoids, including porphyrins, ring-contracted porphyrins, and ring-expanded porphyrins, display excellent radical-stabilizing abilities to the extent that radicals can be handled like usual closed-shell organic molecules. This review surveys four types of stable porphyrinoid radical and covers their synthetic methods and properties such as excellent redox properties, NIR absorption, and magnetic properties...

The first direct C-H 18 F fluorination reaction of unactivated aliphatic sites using no-carrier-added [18 F]fluoride is reported. Under the influence of a manganese porphyrin/iodosylbenzene system, a variety of unactivated aliphatic C-H bonds can be selectively converted to C-18 F bonds. The mild conditions, broad substrate scope and generally inaccessible regiochemistry make this radio-fluorination a powerful alternate to established nucleophilic substitution for the preparation of 18 F labeled radio tracers...

The ubiquitin-proteasome system plays an important role in protein quality control. Currently, inhibition of the proteasome has been validated as a promising approach in anticancer therapy. The 20S core particle of the proteasome harbors β5 subunit which is a crucial active site in proteolysis. Targeting proteasome β5 subunit which is responsible for the chymotrypsin-like activity of small molecules has been regarded as an important way for achieving therapeutics target. In the present study, a series of porphyrin derivatives bearing either pyridine or pyrazole rings as meso-substituents were designed and evaluated as an inhibitor for the β5 subunit of the proteasome by employing molecular docking and dynamics simulations...

We report the synthesis of 23-oxahemiporphycene, the first monooxa analogue of hemiporphycene, a structural isomer of porphyrin. Its generation under McMurry reaction conditions is surprisingly accompanied by the appearance of a formyl derivative of oxacorrole, 5-carbaldehyde-21-oxacorrole. The mechanism of the formation of the latter is proposed, relying on pinacol rearrangement of titanium pinacolate. The structures of the most stable tautomeric forms are established for both compounds using IR and NMR combined with DFT calculations...

Sonodynamic therapy (SDT) can overcome the critical issue of depth-penetration barrier of photo-triggered therapeutic modalities. However, the discovery of sonosensitizers with high sonosensitization efficacy and good stability is still a significant challenge. In this study, the great potential of metal-organic-framework (MOF)-derived carbon nanostructure (PMCS) to act as an excellent sonosensitizer is identified. Excitingly, the superior sonosensitization effect of PMCS is believed to be closely linked to the porphyrin-like macrocycle in MOF-derived nanostructure in comparison to amorphous carbon nanospheres, due to their large highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap for high reactive oxygen species (ROS) production...

Porphyrins have characteristic optical properties which give them potential to be used in a range of applications. In this study a series of β-indandione modified zinc porphyrins, systematically changed in terms of linker length and substituent, resulted in dramatically different absorption spectra than is observed for the parent zinc porphyrin (ZnTXP - 5,10,15,20-tetrakis(3,5-dimethylphenyl)porphyrinato zinc (II)).). These changes included strong absorptions at 420, 541 and 681 nm (110.2, 57.5 and 29.2 mM-1 cm-1, respectively) for the most perturbed compound...

Water stable Zr-metal–organic framework nanoparticles (PCN-224 NPs, PCN refers to porous coordination network) have been solvothermally synthesized. PCN-224 NPs show spherical shape with smooth surface and particle size of approximately 200 nm. PCN-224 NPs can be stable in acid and aqueous solutions, as confirmed by powder X-ray diffraction. Gatifloxacin (GTF) adsorption measurements showed that PCN-224 NPs exhibit a high adsorption capacity of 876 mg·g−1 . Meanwhile, the adsorption factors, adsorption characteristics, and mechanisms of GTF were investigated in batch adsorption experiments...

Mercuric ion (HgII) is a stable form of mercury pollution with high toxicity and bioaccumulation ability, and the sensitive and visible determination is of great importance. Herein, a simple method to magically improve the complexation reaction rate between porphyrin and manganous ions (MnII) have been proposed by using the synergistic effect of trace nitrogen doped graphene quantum dots (NGQDs) and Hg(II). A mechanism is proposed in accordance with a substitution reaction in which the deformed porphyrin nucleus by relatively larger Hg(II) ions is favourable for attacking of small divalent metal ions carried by NGQDs from the back...