Zinc Porphyrin Research Articles

Magnetically Induced Current Densities in Zinc Porphyrin Nanoshells.

The molecular structures of porphyrinoid cages were obtained by constructing small polyhedral graphs whose vertices have degree-4. The initial structures were then fully optimized at the density functional theory (DFT) level using the generalized gradient approximation. Some of polyhedral vertices were replaced with Zn–porphyrin units and their edges were replaced with ethyne or butadiyne bridges or connected by fusing two neighboring Zn–porphyrin units. Molecule 1 is an ethyne-bridge porphyrinoid nanotube, whose ends are sealed with a Zn–porphyrin. Molecule 2 is the corresponding open porphyrinoid nanotube. Molecule 3 is a clam-like porphyrinoid cage, whose shells consist of fused Zn–porphyrins, and the two halves are connected via butadiyne bridges. Molecule 4 is a cross-belt of fused Zn–porphyrins, and molecule 5 is a cross-belt of Zn–porphyrins connected with butadiyne bridges. The magnetically induced current density of the optimized porphyrinoid cages was calculated for determining the aromatic character, the degree of aromaticity and the current-density pathways. The current-density calculations were performed at the DFT level with the gauge—including magnetically induced currents (GIMIC) method using the B3LYP hybrid functional and def2-SVP basis sets. Calculations of the current densities show that molecule 2 sustains a paratropic ring current around the nanotube, whereas sealing the ends as in molecule 1 leads to an almost nonaromatic nanotube. Fusing porphyrinoids as in molecules 3 and 4 results in complicated current-density pathways that differ from the ones usually appearing in porphyrinoids. The aromatic character of molecules 4 and 5 changes upon oxidation. The neutral molecule 4 is antiaromatic, whereas the dication is nonaromatic. Molecule 5 is nonaromatic, and its dication is aromatic.

Zinc porphyrin and rhenium complex-based donor-acceptor conjugated porous polymer for visible-light-driven conversion of CO2 to CO

Visible-light-driven photocatalytic conversion of CO2 into valuable chemicals and fuels is highly desirable but challenging. Herein, we report a donor-acceptor type conjugated porous polymer (ZnPor@Re) consisting of zinc porphyrin as the donor and rhenium complex as the acceptor as an ideal platform for visible-light-driven photocatalytic conversion of CO2 into CO. As expected, ZnPor@Re shows excellent photocatalytic activity for reduction of CO2 under white LED irradiation, achieving up to CO production of 66.2 mmol g–1, selectivity of 99.8% and apparent quantum yield of 1.3% at 420 nm. Time-resolved photoluminescence decay experiment indicates that donor-acceptor structure within the skeleton of ZnPor@Re affords an oriented electron transfer channel of the excited electrons from zinc porphyrin donor to rhenium complex acceptor, thus facilitating separation and transfer of photogenerated charge carries. The current work highlights the great potential of amorphous conjugated porous polymer as photocatalyst for CO2 photoreduction.

Carbon monoxide releasing molecule-2 suppresses stretch-activated atrial natriuretic peptide secretion by activating large-conductance calcium-activated potassium channels.

Carbon monoxide (CO) is a known gaseous bioactive substance found across a wide array of body systems. The administration of low concentrations of CO has been found to exert an anti-inflammatory, anti-apoptotic, anti-hypertensive, and vaso-dilatory effect. To date, however, it has remained unknown whether CO influences atrial natriuretic peptide (ANP) secretion. This study explores the effect of CO on ANP secretion and its associated signaling pathway using isolated beating rat atria. Atrial perfusate was collected for 10 min for use as a control, after which high atrial stretch was induced by increasing the height of the outflow catheter. Carbon monoxide releasing molecule-2 (CORM-2; 10, 50, 100 µM) and hemin (HO-1 inducer; 0.1, 1, 50 µM), but not CORM-3 (10, 50, 100 µM), decreased high stretch-induced ANP secretion. However, zinc porphyrin (HO-1 inhibitor) did not affect ANP secretion. The order of potency for the suppression of ANP secretion was found to be hemin > CORM-2 >> CORM-3. The suppression of ANP secretion by CORM-2 was attenuated by pretreatment with 5-hydroxydecanoic acid, paxilline, and 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one, but not by diltiazem, wortmannin, LY-294002, or NG-nitro-L-arginine methyl ester. Hypoxic conditions attenuated the suppressive effect of CORM-2 on ANP secretion. In sum, these results suggest that CORM-2 suppresses ANP secretion via mitochondrial KATP channels and large conductance Ca2+-activated K+ channels.

Novel 2D Zn-porphyrin metal organic frameworks revived CdS for photocatalysis of hydrogen production

The main challenge of photocatalysis is how to improve the coefficient of utilization and conversion rate for solar energy. Herein, we report a composite photocatalyst related to a novel porphyrin metal organic frameworks (MOFs), in which cadmium sulfide nanoparticles (CdS NPs) are grown in situ on the surface of two-dimensional (2D) zinc porphyrin nanosheets (Zn-TCPP NSs) by hydrothermal method. Interestingly, Zn-TCPP NSs and CdS NPs form a Type II heterojunction structure, which reduces the photogenerated electron-hole recombination rate of CdS. Moreover, in the near-infrared region, the photo-excited electrons generated by Zn-TCPP NSs are transmitted to CdS NPs, so that cadmium sulfide can realize both visible light and near-infrared light for photocatalytic hydrogen production. The Zn-TCPP NSs not only has excellent light absorption capacity, but also has a unique frame design that effectively reduces the recombination rate of photoinduced electron hole pairs, thus improving the conversion rate of solar energy. As expected, the photocatalytic performance of the porphyrin MOFs modified materials is significantly enhanced compared to CdS NPs. The hydrogen production rate of the Pt@CdS NPs/Zn-TCPP NSs(C-Z-T) composite material in the visible light region is about 15.3 mmol g −1 h −1 , which is 11 times for Pt@CdS NPs. Furthermore, the Pt@CdS NPs/Zn-TCPP NSs(C-Z-T) also has a considerable hydrogen production rate in the near-infrared region, such as 200 μmol g −1 h −1 at 600 nm, 90 μmol g −1 h −1 at 765 nm and 20 μmol g −1 h −1 at > 800 nm. • Provides an idea to simultaneously produce hydrogen in visible light and near-infrared light. • Zn porphyrin MOF has a strong ability to separate photogenerated carriers. • The hydrogen production rate of the composite material under visible light is 11 times more than pure CdS.

Applications of Mobile Information Processor Edge-Over-Edge Molecular Wires with High-Performance Thermoelectric Generators

If high-efficiency organic isotherm models for mobile processors can be found, a variety of energy harvesting devices, such as Peltier coolers composed of flexible and transparent thin-film materials, might be manufactured. The thermoelectric characteristics of three zinc porphyrins (ZnP) were studied. Theoretical analyses of electron transport across a potassium (Zn-Diphenyl porphyrin: Zn-DPP) molecular sandwiched between electrode surface with three distinct connections were investigated. The contribution of this research is to see what happens because once pyridine is added above the surface of the zinc-porphyrin skeleton, the “edge-over-edge” dimer created from stacked formed rings has a high electrical conductance, minimal exciton thermal conductance, and a large thermal diffusivity on the order of 300 V K1. At room temperature, these variables add up to a projected ZT 4 figure of merit, the greatest ZT for a single organic molecule ever seen. The stacked arrangement of the porphyrin rings causes low phonon thermal conductance, which delays phonon transport across the edge-over-edge molecule and increases the Seebeck coefficient, resulting in a higher ZT value.

A zinc porphyrin polymer as efficient bifunctional catalyst for conversion of CO2 to cyclic carbonates

AbstractThe design and synthesis of efficient heterogeneous catalysts for catalytic conversion of CO2 are an important challenge. The novel zinc porphyrin polymer reported herein, [ZnPy+CPP‐BTA]I−, is synthesized from trans‐A2B2 porphyrin precursor 5,15‐(4‐carboxyphenyl)‐10,20‐(pyridyl)‐porphyrin (PyCPP) and 1,2,4,5‐benzenetetramine tetrahydrochloride (BTA), employing a sequential post‐synthetic methylation and metalation strategy. The newly synthesized zinc porphyrin polymer was well characterized by Fourier transform infrared spectroscopy (FT‐IR), Ultraviolet–visible spectroscopy (UV–vis), scanning electron microscope (SEM), transmission electron microscope (TEM), thermal gravimetric analysis (TGA), and X‐ray photoelectron spectroscopy (XPS). As bifunctional heterogeneous catalyst incorporated zinc porphyrin and nucleophile I−, [ZnPy+CPP‐BTA]I− shows good catalytic activity and recyclability for the cycloaddition reactions of epoxides and CO2 under lower CO2 initial pressure and cocatalyst‐free conditions.

Carbonic Anhydrase Inhibitors Featuring a Porphyrin Scaffold: Synthesis, Optical and Biological Properties

AbstractThe synthesis, characterization and study of optical properties of innovative tetrafunctionalized zinc(II) porphyrins with carbonic anhydrase (CA) inhibitors in sulfonamide and coumarin series are described. The synthetic methodology relies on the preparation of the porphyrin core by condensation of azido triethyleneglycol functionalized benzaldehyde derivative with pyrrole followed by its metalation and inhibitors couplingviaHuisgen click‐reaction. The tetrafunctionalized zinc(II) porphyrin with coumarin moieties showed selective inhibition against tumour‐associated hCA IX and hCA XIIversusthe cytosolic off‐targets hCA I and hCA II. This compound was able to accumulate on cell membrane and to impair pancreas cancer cells (Capan‐1) proliferation in normoxic conditions with LC50of 4.5 μM. Moreover, its optical properties revealed efficient photosensitizing properties, leading to cancer cells death under light irradiation, making this compound a suitable candidate for photodynamic therapy.

Remotely controllable supramolecular rotor mounted inside a porphyrinic cage

Remotely controllable supramolecular rotor mounted inside a porphyrinic cage

Quest for Zinc Methoxyisoporphyrin Molecules: Experimental and Theoretical Studies

AbstractThis study describes the synthesis, characterization and theoretical studies of two new zinc isoporphyrin compounds, [5‐(methoxy)‐5,10,15,20‐tetrakis(4‐hydroxy)‐5,15H‐porphinato]zinc(II) 1 b, and [5‐(methoxy)‐5,10,15,20‐tetrakis(4‐methyl)‐5,15H‐porphinato]zinc(II) 2 b. Meso‐tetra(4‐hydroxyphenyl)zinc porphyrin, [ZnT(4‐OH)PP], 1 a and, meso‐tetra(4‐methylphenyl)zinc porphyrin, [ZnT(4‐CH3)PP] 2 a were used as a parent porphyrins to synthesize the respective isoporphyrin complexes in the presence of ceric ammonium nitrate (CAN) in methanol medium. The synthesized isoporphyrin compounds are characterized using all standard spectroscopic techniques like UV‐Visible, IR, 1HNMR, and ESI‐Mass spectrometric method. Theoretical calculations at the DFT level was performed to understand the properties and reactivity of the isoporphyrins. To get some insight into the mechanism of isoporphyrin formation via zinc porphyrin dication, the geometry of zinc porphyrin dication [ZnT(4‐OH)PP]++ was optimized and the distribution of Mulliken charge in the dication ring was calculated. The higher positive charge at the meso C‐atoms of the zinc porphyrin dication with respect to other ring carbon atoms supports the proposed nucleophilic attack at the meso carbon of the dication. The DFT calculations studied here is suitable to understand the mechanism of formation of isoporphyrins in the presence of nucleophiles, unique electronic spectra, and redox properties of isoporphyrins.

Supramolecular Chirogenesis in Amide-Linked Bis(Zinc Porphyrin): Application for Absolute Configurational Assignment of Chiral Calboxylic Acids and Chiral Amino Acids

Supramolecular Chirogenesis in Amide-Linked Bis(Zinc Porphyrin): Application for Absolute Configurational Assignment of Chiral Calboxylic Acids and Chiral Amino Acids

Dynamics of the alkyne → copper(I) interaction and its use in a heteroleptic four-component catalytic rotor.

The HETPYNE (HETeroleptic Phenanthroline and alkYNE metal) and DABCO·(zinc porphyrin)2 interactions were used to assemble the four-component nanorotor ROT-1 that exhibited a highly dynamic alkyne → copper(I) dissociation (k298 = 240 kHz) at 298 K. Quantitative click reaction transformed ROT-1 into the new rotor ROT-2 (k298 = 77 kHz) with a triazole → copper(I) linkage thus opening perspectives for bioorthogonal click strategies to biohybrid machinery.

Ligand-binding assay based on microfluidic chemotaxis of porphyrin receptors.

Recent studies have shown that enzymes undergo chemotaxis up substrate gradients during catalysis. One important avenue to identify the molecular level origins of this phenomenon is the ligand-protein binding that occurs even in the absence of catalytic turnover. Here, the chemotaxis of zinc porphyrin as a cofactor mimic was observed by imposing a concentration gradient of organic amines in the microfluidic device. Their axial ligations led to the directed motions of porphyrin receptors. The dissociation constant for selected recognition could be obtained by measuring the chemotactic shift as a function of ligand content, which is associated with both the binding strength and the steric hindrance of the specific ligand. Finally, a statistical thermodynamic model was derived, relating the change of Gibbs free energy (ΔG) in the binding process to the directional migration of receptors. The theoretical model agreed quantitatively with experimental results, elucidating that ΔG of reversible binding essentially drives molecular chemotaxis.

Aromatic heterobicycle-fused porphyrins: impact on aromaticity and excited state electron transfer leading to long-lived charge separation.

A new synthetic method to fuse benzo[4,5]imidazo[2,1-a]isoindole to the porphyrin periphery at the β,β-positions has been developed, and its impact on the aromaticity and electronic structures is investigated. Reactivity investigation of the fused benzoimidazo-isoindole component reveals fluorescence quenching of a zinc porphyrin (AMIm-2) upon treatment with a Brønsted acid. The reaction of the zinc porphyrin (AMIm-2) with methyl iodide initiated a new organic transformation, resulting in the ring-opening of isoindole with the formation of an aldehyde and dimethylation of the benzoimidazo component. The fused benzoimidazo-isoindole component acted as a good ligand to bind platinum(ii), forming novel homobimetallic and heterobimetallic porphyrin complexes. The fusion of benzoimidazo-isoindole on the porphyrin ring resulted in bathochromically shifted absorptions and emissions, reflecting the extended conjugation of the porphyrin π-system. Time-resolved emission and transient absorption spectroscopy revealed stable excited state species of the benzoimidazo-isoindole fused porphyrins. Zinc porphyrin AMIm-2 promoted excited state electron transfer upon coordinating with an electron acceptor, C60, generating a long-lived charge-separated state, in the order of 37.4 μs. The formation of the exceptionally long-lived charge-separated state is attributed to the involvement of both singlet and triplet excited states of AMIm-2, which is rarely reported in porphyrins.

A porphyrin pentamer as a bright emitter for NIR OLEDs.

The luminescence and electroluminescence of an ethyne-linked zinc(ii) porphyrin pentamer have been investigated, by testing blends in two different conjugated polymer matrices, at a range of concentrations. The best results were obtained for blends with the conjugated polymer PIDT-2TPD, at a porphyrin loading of 1 wt%. This host matrix was selected because the excellent overlap between its emission spectrum and the low-energy region of the absorption spectrum of the porphyrin oligomer leads to efficient energy transfer. Thin films of this blend exhibit intense fluorescence in the near-infrared (NIR), with a peak emission wavelength of 886 nm and a photoluminescent quantum yield (PLQY) of 27% in the solid state. Light-emitting diodes (LEDs) fabricated with this blend as the emissive layer achieve average external quantum efficiencies (EQE) of 2.0% with peak emission at 830 nm and a turn-on voltage of 1.6 V. This performance is remarkable for a singlet NIR-emitter; 93% of the photons are emitted in the NIR (λ > 700 nm), indicating that conjugated porphyrin oligomers are promising emitters for non-toxic NIR OLEDs.

Visible-light driven 3-hydroxybutyrate synthesis from CO2 and acetone with the hybrid system of photocatalytic NADH regeneration and multi-biocatalysts.

Poly-3-hydroxybutyrate (PHB)-derived plastics are polymer materials with excellent biodegradability, being insoluble in water and relatively resistant to hydrolysis. There is a need for a method capable of synthesizing 3-hydroxybutyrate, a monomer of PHB, from a renewable material. In this work, visible-light driven 3-hydroxybutyrate from CO2 and acetone with the system consisting of triethanolamine, water-soluble zinc porphyrin, pentamethylcyclopentadienyl coordinated rhodium complex, NAD+ and a cell extract containing acetone carboxylase and 3-hydroxybutyrate dehydrogenase from Rhodobacter capsulatus SB1003 cultured in acetone-bicarbonate medium is established. In particular, the conversion yield for acetone to 3-hydroxybutyrate was improved up to 81% in this system after 7 h irradiation.

Iron and zinc porphyrin linked MoO(dithiolene) complexes in relevance to electron transfer between Mo-cofactor and cytochrome b5 in sulfite oxidase.

Oxo-molybdenum (dithiolene) complexes covalently linked individually to iron and zinc porphyrin have been synthesized to show an electron transfer between the two metal centres in relevance to electron transfer from Mo-cofactor to cytochrome b5 domains in the oxidative half of the catalytic cycle of native sulfite oxidase. This association has been investigated by electrochemical, EPR measurement and X-ray absorbance spectroscopy techniques.

Third-order optical nonlinearities of zinc porphyrins accommodated in the cavity of a doughnut-like molybdenum crown cluster

As compared with the pristine ZnTCPP, the hybrid 1 showed quenched fluorescence, greater nonlinear reverse saturated absorption and self-defocusing effect, smaller nonlinear optical limiting threshold, indicating its high potential in optical limiting applications.

Photophysical behaviors of a shape-persistent zinc porphyrin organic cage

A pair of chiral zinc porphyrin cages with a monomeric reference have been prepared, and differences in photophysical behaviors have been systematically explored.

Supramolecular cuboctahedra with aggregation-induced emission enhancement and external binding ability.

Beyond the AIE (aggregation-induced emission) phenomenon in small molecules, supramolecules with AIE properties have evolved in the AIE family and accelerated the growth of supramolecular application diversity. Inspired by its mechanism, particularly the RIV (restriction of intramolecular vibrations) process, a feasible strategy of constructing an AIE-supramolecular cage based on the oxidation of sulfur atoms and coordination of metals is presented. In contrast to previous strategies that used molecular stacking to limit molecular vibrations, we achieved the desired goal using the synergistic effects of coordination-driven self-assembly and oxidation. Upon assembling with zinc ions, S1 was endowed with a distinct AIE property compared with its ligand L1, while S2 exhibited a remarkable fluorescence enhancement compared to L2. Also, the single cage-sized nanowire structure of supramolecules was obtained via directional electrostatic interactions with multiple anions and rigid-shaped cationic cages. Moreover, the adducts of zinc porphyrin and supramolecules were investigated and characterized by 2D DOSY, ESI-MS, TWIM-MS, UV-vis, and fluorescence spectroscopy. The protocol described here enriches the ongoing research on tunable fluorescence materials and paves the way towards constructing stimuli-responsive luminescent supramolecular cages.

Visible-light-induced enzymatic reactions using an NADH regeneration system of water-soluble zinc porphyrin and homogeneous colloidal rhodium nanoparticles

Visible-light-driven molecular conversion using the NADH regeneration system of triethanol amine, water-soluble zinc porphyrin, colloidal Rh nanoparticles and NAD+ in the presence of various dehydrogenases was developed.