Zn Porphyrin Research Articles

Conformational Switching of A Nano-Size Urea-bridged Zn(II)Porphyrin Dimer by External Stimuli.

For the first time, explicit stabilization of all the three conformers, viz. (cis,cis), (cis,trans) and (trans,trans), of a 'nano-sized' highly-flexible urea-bridged Zn(II)porphyrin dimer have been achieved via careful manipulations of external stimuli such as solvent dielectrics, temperature, anionic interactions, axial ligation and surface-induced stabilization. The conformers differ widely in their structures, chemical and photophysical properties and thus have vast potential applicability. X-ray structural characterizations have been reported for the (cis,cis) and (cis,trans)-conformers. While (cis,cis) conformer stabilized exclusively in dichloromethane, more polar solvents resulted in the stabilization of (cis,trans) and (trans,trans)-conformers. Low temperature promotes the stabilization of (cis,trans)-conformer while rise in temperature facilitates flipping to the (cis,cis) one. Significantly, exclusive stabilization of the (trans,trans)-isomer has been illustrated using acetate anion which facilitates H-bonding with the two amide linkages of the urea spacer. Remarkably, HOPG surface facilitates stabilization of the energetically challenging (trans,trans)-conformer via CH···p and p···p interactions with the solid surface to the porphyrinic cores. DFT calculations demonstrate that the relative stability of the conformers can be modulated upon slight external perturbations as also observed in the experiment. Several factors contributing towards the conformational landscape for the highly flexible urea-bridged porphyrin dimers have been mapped.

Rigid and Flexible Bis-Porphyrinic Tweezers: Efficient Molecular Recognition of Bidentate Bases

Increasing efforts are devoted to the synthesis of cofacial bis-porphyrinic tweezers able to complex various bidentate guests through axial coordination of the Zn(II) porphyrins by the two nitrogen atoms. Elaboration of rigid receptors appeared up to now as the ideal way to pre-organize a bis-porphyrinic cavity and increase the stability of the formed host/guest complexes. However, the choice of using rigid spacer to attach the two porphyrins together may cost a lot as far as solubility and stability are concerned. The synthetic pathways necessary to achieve the synthesis of rigid systems are frequently long and tedious. We report here the synthesis and studies of new flexible bis-porphyrinic tweezers bearing uridine as linkers and offering pre-organized cavities able to welcome bidentate guests with extremely high association constants.As part of our studies concerning complexation of bidentate Lewis bases by bis-porphyrinic tweezers, we have synthesized two new bis-porphyrins bearing a flexible nucleosidic linker. Both uridine and 2’-deoxyuridine spacers were chosen on account of some observations we made a few years ago on the unexpected blocked conformations adopted by a pentaporphyrin consisting of four Zn(II) porphyrins attached to a central free-base porphyrin by four nucleosidic linkers. Since we observed no such blocked conformations in other flexible pentaporphyrins, we thought this might be due to the nucleosidic nature of the linkers. We thus synthesized two dimers, which differ by the attachment positions of the two porphyrins.The ability of these two tweezers to accomodate guests was investigated through ligand binding studies carried out in dichloromethane with DABCO as bidentate base. The complexation of DABCO by these dimers was monitored by UV-visible spectrophotometric titration in CH2Cl2. The binding constants between these two tweezers and DABCO were calculated from UV-visible spectroscopic data. These association constants are unexpectedly increased by more than one order of magnitude as compared to the association constants of the same bidentate ligand with a reference Zn(II) mono-porphyrin. This enhanced stability of the complexes may be ascribed to a pre-organization of the bis-porphyrinic tweezers forming a cavity, and provides convincing evidence that the bidentate base is inserted into the cavity of the dimers via host/guest interactions.We demonstrated that similar association constants can be obtained with flexible tweezers bearing uridine as linker and rigid tweezers. However, the stability of these flexible complexes isn’t as convincing as for our rigid tweezers bearing a tris-anthracenic spacer since the addition of an excess of DABCO destroys all the flexible complexes.Molecular modelling of one of the flexible tweezers and its 1/1 complex with DABCO is represented below, as well as our rigid tweezers bearing a tris-anthracenic spacer. Acknowledgements This work was supported by the CNRS and the French Ministry of Research.

Molecular Level Insights into the Chemical Reactivity of Metal Porphyrins and Iodine at the Solution/Solid Interface

Highly oxidized metalloporphyrins (MP) exhibit unusual electronic properties and unique reactivities and are known to serve as intermediates in a number of biological reactions. Of special interest are MP systems that can electronically communicate during the oxidative processes. Model synthetic porphyrins substituted with first row transition metals can react with dihalides and undergo metal oxidation or form MP p-cation radicals. MP dimers that are covalently connected by short alkane or alkene bridges exhibit electronic coupling between the macrocycles which can strongly influence the outcome of the oxidation reaction by dihalides. Metal surfaces also can serve as a conduit for electron transfer and promote cooperative behavior during reactions between adsorbed MP and axial ligands. In this contribution, we present STM experimental results and supporting theoretical calculations of the reactions dynamics of I2 and metal (Co, Zn, and Ni) porphyrins adsorbed on metallic supports. Single molecule level STM imaging was accomplished in-situ under ambient solution conditions. We uncovered unusual surface chemistry and surface modulated cooperativity in the redox reactions. Computations corroborate our experimental findings. The high-resolution images obtained for these reactions at the single molecule level combined with theoretical studies offer insights into surface redox chemistry, surface cooperativity, and surface-driven catalysis.

Nucleosides as Organizing Architectural Moieties

Chemistry “beyond the molecule” is epitomized in nature by a plethora of relatively weak noncovalent interactions. The three-dimensional structures of most biopolymers are controlled with noncovalent interactions, either between different parts of the same strand (as in protein α-helices) or between two separate strands (as in the DNA duplex and protein β-sheet). While nature has refined the construction of biopolymers, our mastery of the subtle noncovalent interactions as synthetic tools is in an early stage of development. Only in the past two decades people begun to develop ways of mimicking the natural light-harvesting complexes by noncovalent assembly of porphyrin units aiming to obtain favored spacing and orientation between the chromophores. The construction of multi-chromophoric assemblies has led to resurgence of interest in coordination chemistry due to formation of ordered arrays directed through molecular recognition events. As a module in the construction of supramolecular assemblies, porphyrins and metallo-porphyrins can be exploited in two different ways: porphyrins can behave as donor building blocks insofar as they comprise meso-substituents, such as pyridyl groups, which can act as ligands that can suitably coordinate to metal cations, while metalloporphyrins can act as acceptor building blocks as soon as the metal atom inside the porphyrin core has at least one axial site available for coordination. For the last years, we have focussed on cofacial bis-porphyrin tweezers for host/guest interactions and investigated the possibilty to obtain self-coordinated molecular systems with predictable spectral and redox characteristics. We report here the synthesis of a di-nucleotide bearing pendant porphyrins dedicated to adopt a pre-organized coformation with face-to-face porphyrins, and capable to self-organize in a stable sandwich type complexe with bidentate base such as DABCO.1 Using a similar strategy as the one used in antisense research, an artificial nucleotidic backbone was built from modified deoxy-uridine units linked with a more rigid linker than the phosphodiester moieties found in natural oligonucleotides. Antisense research uses modified oligonucleotides, less flexible than natural strands, to pre-organize the system toward the obtaining of stable double helices between synthesized and natural oligonucleotides. A modified oligonucleotidic backbone was here used to target a parallel conformation of the porphyrins appended to each deoxy-uridine moiety. To provide a rigid environment for the porphyrins, the uridine units were coupled in 3’-5’ stepwise fashion using ether-ester type of spacer of suitable length, and porphyrins were anchored to the uridine by means of robust carbon-carbon bonds.Earlier studies demonstrated that a peptidic linker doesn’t provide sufficient pre-organization to enhance significantly the association constant with bidentate bases such as DABCO on the contrary of some flexible linkers such as uridine or 2’-deoxyuridine. We document herein that the gain in stability for the formation of sandwich type host-guest complex with DABCO can be even greater when a dinucleotide linker is used. Such pre-organization increases the association constants by one to two orders of magnitude when compared to the association constants of the same bidentate ligands with a reference Zn(II) porphyrin. Comparison of these results with those obtained for rigid tweezers shows a better efficiency of the flexible nucleosidic dimers.We thus document the fact that the choice of rigid spacers is not the only way to pre-organize bis-porphyrins, and that some well-chosen nucleosidic linkers offer an interesting option for the synthesis of such devices. Furthermore, the chirality and enantio-purity of the nucleosidic linkers paves the way toward the selective complexation of enantio-pure bidentate guests and the resolution of racemates. Acknowledgements This work was supported by the CNRS and the French Ministry of Research. References Solladié, R. Rein, S. Bouatra, S. Merkas, C. Sooambar, I. Piantanida, M. Žinić, J. Porphyrins Phthalocyanines 2020, 24, 636-645.

How the Interplay between SnO2 and Zn(II) Porphyrins Impacts on the Electronic Features of Gaseous Acetone Chemiresistors.

Herein, the integration of SnO2 nanoparticles with two Zn(II) porphyrins─Zn(II) 5,10,15,20-tetraphenylporphyrin (ZnTPP) and its perfluorinated counterpart, Zn(II) 5,10,15,20-tetrakis(pentafluorophenyl)porphyrin (ZnTPPF20)─was investigated for the sensing of gaseous acetone at 120 °C, adopting three Zn-porphyrin/SnO2 weight ratios (1:4, 1:32, and 1:64). For the first time, we were able to provide evidence of the correlation between the materials' conductivity and these nanocomposites' sensing performances, obtaining optimal results with a 1:32 ratio for ZnTPPF20/SnO2 and showcasing a remarkable detection limit of 200 ppb together with a boosted sensing signal with respect to bare SnO2. To delve deeper, the combination of experimental data with density functional theory calculations unveiled an electron-donating behavior of both porphyrins when interacting with tin dioxide semiconductor, especially for the nonfluorinated one. The study suggested that the interplay between electrons injected, from the porphyrins' highest occupied molecular orbital to SnO2 conduction band, and the latter's available electronic states has a dramatic impact to boost the chemiresistive sensing. Indeed, we highlighted that the key lies in preventing the full saturation of SnO2 electronic states concomitantly increasing the materials' conductivity: in this respect, the best compromise turned out to be the perfluorinated porphyrin. A further corroboration of our findings was obtained by illuminating the sensors during measurements with light-emitting diode (LED) light. Actually, we demonstrated that it does not have any impact on improving the sensing behavior, most probably due to the electronic oversaturation and scattering caused by LED excitation in porphyrins. Lastly, the most effective hybrids (1:32 ratio) were physicochemically characterized, confirming the physisorption of the macrocycles onto the SnO2 surface. In conclusion, herein, we underscore the feasibility of customizing the porphyrin chemistry and porphyrin-to-SnO2 ratio to enhance the gaseous sensing of bare metal oxides, providing valuable insights for the engineering of highly performing light-free chemiresistors.

Supramolecular Self-Assembled Nanostructures Derived from Amplified Structural Isomerism of Zn(II)-Sn(IV)-Zn(II) Porphyrin Triads and Their Visible Light Photocatalytic Degradation of Pollutants.

Two structural isomeric porphyrin-based triads (Zn(II)porphyrin-Sn(IV)porphyrin-Zn(II)porphyrin) denoted as T1 and T2 were prepared from the reaction of meso-[5-(4-hydroxyphenyl)-10,15,20-tris(3,5-di-tert-butylphenyl)porphyrinato]zinc(II) (ZnL) with trans-dihydroxo-[5,10-bis(3-pyridyl)-15,20-bis(phenyl)porphyrinato]tin(IV) (SnP1) and trans-dihydroxo-[5,15-bis(3-pyridyl)-10,20-bis(phenyl)porphyrinato]tin(IV) (SnP2), respectively. All the compounds were characterized using UV-vis spectroscopy, emission spectroscopy, ESI-MS, 1H NMR spectroscopy, and FE-SEM. Most importantly, the two structurally isomeric porphyrin-based triads supramolecularly self-assembled into completely different nanostructures. T1 exhibits a nanosphere morphology, whereas T2 exhibits a nanofiber morphology. The amplified geometric feature in the structural isomeric porphyrin-based triads dictates the physical and chemical properties of the two triads. Both compounds showed the morphology-dependent visible light catalytic photodegradation of rhodamine B dye (74-97% within 90 min) and tetracycline antibiotic (44-71% within 45 min) in water. In both cases, the photodegradation efficiency of T2 was higher than that of T1. The present investigation can significantly contribute to the remediation of wastewater by tuning the conformational changes in porphyrin-based photocatalysts.

Enhancement of Photodetector Characteristics by Zn-Porphyrin-Passivated MAPbBr3 Single Crystals.

Perovskite single crystals have garnered significant interest in photodetector applications due to their exceptional optoelectronic properties. The outstanding crystalline quality of these materials further enhances their potential for efficient charge transport, making them promising candidates for next-generation photodetector devices. This article reports the synthesis of methyl ammonium lead bromide (MAPbBr3) perovskite single crystal (SC) via the inverse-temperature crystallization method. To further improve the performance of the photodetector, Zn-porphyrin (Zn-PP) was used as a passivating agent during the growth of SC. The optical characterization confirmed the enhancement of optical properties with Zn-PP passivation. On single-crystal surfaces, integrated photodetectors are fabricated, and their photodetection performances are evaluated. The results show that the single-crystalline photodetector passivated with 0.05% Zn-PP enhanced photodetection properties and rapid response speed. The photoelectric performance of the device, including its responsivity (R), external quantum efficiency (EQE), detective nature (D), and noise-equivalent power (NEP), showed an enhancement of the un-passivated devices. This development introduces a new potential to employ high-quality perovskite single-crystal-based devices for more advanced optoelectronics.

Cover Feature: Use of Ferrocenyl Ni(II) and Zn(II) Porphyrins as Active Organic Electrode Materials for Sodium Secondary Batteries (Batteries & Supercaps 6/2024)

Cover Feature: Use of Ferrocenyl Ni(II) and Zn(II) Porphyrins as Active Organic Electrode Materials for Sodium Secondary Batteries (Batteries & Supercaps 6/2024)

Interactions of Co(II)- and Zn(II)porphyrin of 5,10,15,20-tetrakis(1-methyl-4-pyridinio)porphyrin with DNA in Aqueous Solution and Their Antimicrobial Activities.

Antibiotics are frequently used to treat, prevent, or control bacterial infections, but in recent years, infections resistant to all known classes of conventional antibiotics have significantly grown. The development of novel, nontoxic, and nonincursive antimicrobial methods that work more quickly and efficiently than the present antibiotics is required to combat this growing public health issue. Here, Co(II) and Zn(II) derivatives of tetrakis(1-methylpyridinium-4yl)porphyrin [H2TMPyP]4+ as a tetra(ρ-toluenesulfonate) were synthesized and purified to investigate their interactions with DNA (pH 7.40, 25 °C) using UV-vis, fluorescence techniques, and antimicrobial activity. UV-vis results showed that [H2TMPyP]4+ had a high hypochromicity (∼64%) and a substantial bathochromic shift (Δλ, 14 nm), while [Co(II)TMPyP]4+ and [Zn(II)TMPyP]4+ showed little hypochromicity (∼37%) and a small bathochromic shift (Δλ, 3-6 nm). Results reveal that [H2TMPyP]4+ interacts with DNA via intercalation, while Co(II)- and [Zn(II)TMPyP]4+ interact with DNA via outside self-stacking. Fluorescence results also confirmed the interaction of [H2TMPyP]4+ and the metalloporphyrins with DNA. Results of the antimicrobial activity assay revealed that the metalloporphyrins showed inhibitory effects on Gram-positive and Gram-negative bacteria and fungi, but that neither the counterions nor [H2TMPyP]4+ exhibited any inhibitory effects. Mechanism of antimicrobial activities of metalloporphyrins are discussed.

Zn–Porphyrin Antisolvent Engineering‐Enhanced Grain Boundary Passivation for High‐Performance Perovskite Solar Cell

Perovskite solar cells (PSCs) represent a promising and rapidly evolving technology in the field of photovoltaics due to their easy fabrication, low‐cost materials, and remarkable efficiency improvements over a relatively short period. However, the grain boundaries in the polycrystalline films exhibit a high density of defects, resulting in not only heightened reactivity to oxygen and water but also hampered charge transport and long‐term stability. Herein, an approach involving Zn‐porphyrin (Zn‐PP)‐upgraded antisolvent treatment to enhance the grain size and meanwhile passivate grain boundary defects in FA0.95MA0.05PbI2.85Br0.15 perovskites is presented. The Zn‐PP molecules significantly improve structural and optical properties, effectively mitigating defects and promoting carrier transport at the perovskite/hole transport layer interface. The density functional theory simulation confirms that Zn‐PP forms a strong chemical bonding with the perovskite surface. With Zn‐PP passivation, the total density of state shifts to higher‐energy regions with molecular adsorption, especially near the valence and conduction band edges, indicating that there is an increase in conducting properties of the surface with molecular adsorption. The power conversion efficiency (PCE) of PSCs increases significantly as a result of this improvement, rising from 15.38% to 19.11%. Moreover, unencapsulated PSCs treated with Zn‐PP exhibit outstanding stability, retaining over 91% of their initial PCE.

Use of Ferrocenyl Ni(II) and Zn(II) Porphyrins as Active Organic Electrode Materials for Sodium Secondary Batteries

AbstractThis study investigates the potential use of ferrocenyl‐substituted porphyrins as organic electrode materials for sodium secondary batteries. Expressly, 5,15‐di(ferrocenyl)‐10,20‐di(pentafluorophenyl)porphyrins (free base, Fc−H2Por), along with its zinc (Zn[II] complex, Fc−ZnPor) and nickel (Ni[II] complex, Fc−NiPor) derivatives were synthesized and employed as the electrode materials. The charge‐discharge processes disclosed that the ferrocenyl‐substituted porphyrin compound performs electrochemical processes poorly without chelating metals. In contrast, when the ferrocenyl‐substituted porphyrins were metalated with Ni(II) and Zn(II), they exhibited dual ionic charge‐discharge capabilities, indicating their stable electrochemical properties. In particular, long‐term cycle tests emphasized the superior stability and high Coulombic efficiency of Fc−ZnPor electrodes. Computational calculations provided conclusive evidence of variances in aromatic stabilization energy based on the metal center, significantly influencing the chemical stability and electrochemical performance. These findings can deliver valuable insight for further development and optimizations in energy storage applications.

Perfluorinated Zinc Porphyrin Sensitized Photoelectrosynthetic Cells for Enhanced TEMPO-Mediated Benzyl Alcohol Oxidation.

This research introduces a novel series of perfluorinated Zn(II) porphyrins with positive oxidation potentials designed as sensitizers for photoelectrosynthetic cells, with a focus on promoting the oxidation of benzyl alcohol (BzOH) mediated by the 2,2,6,6-tetramethyl-1-piperidine N-oxyl (TEMPO) organocatalyst. Three dyes, CLICK-3, CLICK-4, and BETA-4, are meticulously designed to explore the impact of substituents and their positions on the perfluorinated porphyrin ring in terms of redox potentials and energy level alignment when coupled with SnO2/TiO2-based photoanodes and TEMPO mediator. A comprehensive analysis utilizing spectroscopy, electrochemistry, photophysics, and computational techniques of the dyes in solution and sensitized thin films unveils an enhanced charge-separation character in the 4D-π-1A type BETA-4. Incorporating four dimethylamino donor groups at the periphery of the porphyrin ring and a BTD-accepting linker at the β-pyrrolic position equips the structure with a more efficient donor-acceptor system. This enhancement ensures improved light-harvesting capacity, resulting in a doubled incident photon-to-current conversion efficiency (IPCE% ≃30%) in the presence of LiI compared to meso-substituted dyes CLICK-3 and CLICK-4. Sensitizing SnO2/TiO2 thin films with BETA-4 successfully promotes the photooxidation of benzyl alcohol (BzOH) in the presence of the rapid TEMPO radical catalyst, yielding photocurrents of approximately 125 μA/cm2 in an optimized TBPy/LiClO4/ACN electrolyte. Notably, when lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) replaces TBPy as the base for TEMPO-catalyzed BzOH oxidation, a remarkable photocurrent of around 800 μA/cm2 is achieved, marking one of the highest values reported for this photoelectrochemical reaction to date. This study underscores that the proper functionalization of perfluorinated zinc porphyrins positions these dyes as ideal candidates for sensitizing SnO2/TiO2 in the photodriven oxidation of BzOH. It also highlights the crucial role of carefully tuning electrolyte composition based on the electronic properties of molecular sensitizers.

Using the fermi level as a predictive indicator of the electrocatalytic activities displayed by single-atom catalysts in sulfur cathode reactions

Single-atom catalysts (SACs) have emerged as promising candidates for promoting sulfur cathode kinetics. Despite the growing popularity, the literature is devoid of general guidelines for predicting the electrocatalytic effects exerted by novel SACs. Herein, a series of SACs immobilized on N-doped graphene were prepared from metal (Mn, Ni, Cu, or Zn) porphyrins. The Fermi levels of the catalysts were found to be inversely correlated with their electrocatalytic effects. For example, the Ni-based SACs exhibited the lowest Fermi level but showed the strongest binding affinity to sulfur. As a result, Li−S cells containing Ni SACs exhibited a high specific capacity (10.0 mA h cm−2 at 0.05 C), excellent cycling stability (6.7 mA h cm−2 at 0.1 C after 100 cycles) and other remarkable performance metrics even at a high sulfur loading of 9.6 mg cm−2. The methodology offers a way to evaluate the catalytic activities of SACs rapidly and efficiently, particularly in electrocatalytic systems.

Bioinspired Self-Assembly of Metalloporphyrins and Polyelectrolytes into Hierarchical Supramolecular Nanostructures for Enhanced Photocatalytic H2 Production in Water.

Polypeptides, as natural polyelectrolytes, are assembled into tailored proteins to integrate chromophores and catalytic sites for photosynthesis. Mimicking nature to create the water-soluble nanoassemblies from synthetic polyelectrolytes and photocatalytic molecular species for artificial photosynthesis is still rare. Here, we report the enhancement of the full-spectrum solar-light-driven H2 production within a supramolecular system built by the co-assembly of anionic metalloporphyrins with cationic polyelectrolytes in water. This supramolecular photocatalytic system achieves a H2 production rate of 793 and 685 μmol h-1 g-1 over 24 h with a combination of Mg or Zn porphyrin as photosensitizers and Cu porphyrin as a catalyst, which is more than 23 times higher than that of free molecular controls. With a photosensitizer to catalyst ratio of 10000 : 1, the highest H2 production rate of >51,700 μmol h-1 g-1 with a turnover number (TON) of >1,290 per molecular catalyst was achieved over 24 h irradiation. The hierarchical self-assembly not only enhances photostability through forming ordered stackings of the metalloporphyrins but also facilitates both energy and electron transfer from antenna molecules to catalysts, and therefore promotes the photocatalysis. This study provides structural and mechanistic insights into the self-assembly enhanced photostability and catalytic performance of supramolecular photocatalytic systems.

Bioinspired Self‐Assembly of Metalloporphyrins and Polyelectrolytes into Hierarchical Supramolecular Nanostructures for Enhanced Photocatalytic H2 Production in Water

AbstractPolypeptides, as natural polyelectrolytes, are assembled into tailored proteins to integrate chromophores and catalytic sites for photosynthesis. Mimicking nature to create the water‐soluble nanoassemblies from synthetic polyelectrolytes and photocatalytic molecular species for artificial photosynthesis is still rare. Here, we report the enhancement of the full‐spectrum solar‐light‐driven H2 production within a supramolecular system built by the co‐assembly of anionic metalloporphyrins with cationic polyelectrolytes in water. This supramolecular photocatalytic system achieves a H2 production rate of 793 and 685 μmol h−1 g−1 over 24 h with a combination of Mg or Zn porphyrin as photosensitizers and Cu porphyrin as a catalyst, which is more than 23 times higher than that of free molecular controls. With a photosensitizer to catalyst ratio of 10000 : 1, the highest H2 production rate of >51,700 μmol h−1 g−1 with a turnover number (TON) of >1,290 per molecular catalyst was achieved over 24 h irradiation. The hierarchical self‐assembly not only enhances photostability through forming ordered stackings of the metalloporphyrins but also facilitates both energy and electron transfer from antenna molecules to catalysts, and therefore promotes the photocatalysis. This study provides structural and mechanistic insights into the self‐assembly enhanced photostability and catalytic performance of supramolecular photocatalytic systems.

Acquiring of photosensitivity by Mycobacterium tuberculosis in vitro and inside infected macrophages is associated with accumulation of endogenous Zn–porphyrins

Mycobacterium tuberculosis (Mtb) is able to transition into a dormant state, causing the latent state of tuberculosis. Dormant mycobacteria acquire resistance to all known antibacterial drugs and can survive in the human body for decades before becoming active. In the dormant forms of M. tuberculosis, the synthesis of porphyrins and its Zn-complexes significantly increased when 5-aminolevulinic acid (ALA) was added to the growth medium. Transcriptome analysis revealed an activation of 8 genes involved in the metabolism of tetrapyrroles during the Mtb transition into a dormant state, which may lead to the observed accumulation of free porphyrins. Dormant Mtb viability was reduced by more than 99.99% under illumination for 30 min (300 J/cm2) with 565 nm light that correspond for Zn–porphyrin and coproporphyrin absorptions. We did not observe any PDI effect in vitro using active bacteria grown without ALA. However, after accumulation of active cells in lung macrophages and their persistence within macrophages for several days in the presence of ALA, a significant sensitivity of active Mtb cells (ca. 99.99%) to light exposure was developed. These findings create a perspective for the treatment of latent and multidrug-resistant tuberculosis by the eradication of the pathogen in order to prevent recurrence of this disease.

Narcissistic self-sorting in Zn(II) porphyrin derived semiconducting nanostructures.

The narcissistic self-sorted phenomenon is explicitly attributed to the structural similarities in organic molecules. Although such relevant materials are rarely explored, self-sorted structures from macrocyclic π-conjugated-based p- and n-type organic semiconductors facilitate the increase of exciton dissociation and charge separation in bulk heterojunction solar cells. Herein, we report two extended π-conjugated derivatives consisting of zinc-porphyrin-linked benzothiadiazole acting as an acceptor (PB) and anthracene as a donor (PA). Despite having the same porphyrin π-conjugated core in PA and PB, variations in donor and acceptor moieties make the molecular packing form one-dimensional (1D) self-assembled nanofibers via H- and J-type aggregates. Interestingly, a dissimilar aggregate of PA and PB exists as a mixture (PA + PB), promoting narcissistic self-sorted structures. Electrochemical impedance investigation reveals that the electronic characteristics of self-sorting assemblies are influenced by the difference in electrostatic potentials for PA and PB, resulting in a transitional electrical conductivity of 0.14 S cm-1. Therefore, the design of such materials for the fabrication of effective photovoltaics is promoted by these extraordinary self-sorted behaviors in comparable organic π-conjugated molecules.

A zinc–porphyrin–peptide conjugate via “click-chemistry”: synthesis and amyloid-β interaction

A Zn–porphyrin–peptide conjugate was obtained by click-reaction between an alkyne-porphyrin and the azido-peptide of KLVFF. The peptide showed an induced dichroic signal in the presence of Aβ42 and no toxicity on neuronal cells.

Synthesis and Photocatalytic CO2 Reduction of a Cyclic Zinc(II) Porphyrin Trimer with an Encapsulated Rhenium(I) Bipyridine Tricarbonyl Complex.

We previously reported a cyclic Zn(II) porphyrin trimer in which three Zn porphyrins are alternately bridged by three 2,2'-bipyridine (bpy) moieties, enabling the encapsulation of metal complexes within the nanopore formed by the Zn porphyrins. In this study, we introduced a [Re(CO)3 Br] fragment into one of the bpy moieties of the cyclic trimer to form the catalytic Re(4,4'-R2 -bpy)(CO)3 Br center (R=methyl ester). The ester groups (R) play an important role in the synthesis of the cyclic structure. However, it was observed that these ester groups significantly deactivated the photocatalytic CO2 reduction reaction. Therefore, we converted the ester groups with a suitable reducing reagent into hydroxymethyl groups, followed by acetylation to form acetoxymethyl groups. This modification remarkably enhanced the photocatalytic activity of the cyclic trimer=Re complex system for CO2 reduction. Moreover, in the modified system, the presence of the Re complex induced room-temperature phosphorescence of the Zn porphyrin. The phosphorescence was significantly quenched by 1,3-dimethyl-2-phenyl-2,3-dihydro-1H-benzo[d]imidazole, indicating that efficient electron transfer mediated by the excited triplet state of the Zn porphyrin occurs during the photocatalytic CO2 reduction.

Porphene and porphite as porphyrin analogs of graphene and graphite

Two-dimensional materials have unusual properties and promise applications in nanoelectronics, spintronics, photonics, (electro)catalysis, separations, and elsewhere. Most are inorganic and their properties are difficult to tune. Here we report the preparation of Zn porphene, a member of the previously only hypothetical organic metalloporphene family. Similar to graphene, these also are fully conjugated two-dimensional polymers, but are composed of fused metalloporphyrin rings. Zn porphene is synthesized on water surface by two-dimensional oxidative polymerization of a Langmuir layer of Zn porphyrin with K2IrCl6, reminiscent of known one-dimensional polymerization of pyrroles. It is transferable to other substrates and bridges μm-sized pits. Contrary to previous theoretical predictions of metallic conductivity, it is a p-type semiconductor due to a predicted Peierls distortion of its unit cell from square to rectangular, analogous to the appearance of bond-length alternation in antiaromatic molecules. The observed reversible insertion of various metal ions, possibly carrying a fifth or sixth ligand, promises tunability and even patterning of circuits on an atomic canvas without removing any π centers from conjugation.