Tetraphenylporphyrin Derivatives Research Articles

Tuning Transition Metal‐Containing Molecular Magnets by On‐Surface Polymerization

AbstractPorphyrins are promising multifunctional units particularly interesting for the realization of molecular nanodevices. Their structural variety allows to create precursors suitable for the on‐surface polymerization of porphyrin blocks. The corresponding increased stability and improved transport properties of the formed polymerized molecular nanostructures make them practically worthwhile. For the case of 2D porphyrin materials, the effect of polymerization on the magnetic properties of transition metal ions has not been reported yet. Therefore, details on the properties of an extended covalent nickel tetraphenylporphyrin network formed via Ullmann coupling on the Cu(111) surface are reported. By using photoelectron and absorption spectroscopies together with density functional theory calculations, it is systematically evolving how the functional properties of the Ni centers are changed within a polymerized molecular structure in comparison to single‐molecule nickel tetraphenylporphyrin derivatives that build the 2D molecular network. A model that explains the differences in the electronic and magnetic properties observed for the Ni centers in both structures based on the additional rigidity characteristic of the molecular layer after polymerization is drawn.

Exploring copper (II) porphyrin complexes and their derivatives for electrochemical analysis and biological assessment in the study of breast cancer (MCF-7) cell lines

In this study, several derivatives of tetraphenylporphyrin were synthesized, each with unique meso-substituent groups including phenyl, methoxyphenyl, butyloxyphenyl, octyloxyphenyl, and dectyloxyphenyl. Additionally, their corresponding copper complexes were prepared and thoroughly characterized. The structural confirmation of all compounds was established through CHN elemental analysis, mass spectrometry, and FT-IR spectroscopy. As the number of carbon atoms in the alkyl long-chain increased, a slight red shift in the electronic absorption band was observed, which was attributed to the electronic influence of the alkyl group. DFT analysis indicated that electron density predominantly localized on the porphyrin ring of both the metal free porphyrins and copper (II) porphyrin complexes, with relatively low electron density in the p orbital of the meso-aryl long-chain substituent group. EPR spectroscopy of the Copper (II) ion complexes revealed signals, indicating their paramagnetic properties. Additionally, the Copper (II) tetraphenylporphyrin (CuTPP) complexes displayed two reversible oxidation peaks at +0.97 V and +1.35 V, whereas other derivatives exhibited lower oxidation potentials. The cytotoxicity of these compounds against MCF-7 cell lines was assessed using MTT assay, revealing cytotoxic effects in all cases. Among them, Copper (II) tetrakis (4-methyloxyphenyl)porphyrin (CuTOMPP) demonstrated the highest potential, with an IC50 value of 32.07 μg/mL.

Quest for iron(III) isoporphyrins: Synthesis, characterization, reactivity and theoretical studies

Detailed studies on iron(III) isoporphyrins, which are isoelectronic with iron(IV)-oxo porphyrin radical and very much reactive in nature are rare in the literature. Therefore, here we have reported the synthesis of a series of methoxy iron(III) isoporphyrins of tetraphenylporphyrin derivatives using chemical oxidants and characterized well with UV–Visible, IR, ESI-Mass, elemental analysis, thermal gravimetric studies (TGA), Powder X-Ray Diffraction studies and 1H NMR spectroscopy. The electrochemical studies were performed for the first time on such type iron(III) isoporphyrins. ESR and magnetic susceptibility studies supported the high-spin iron(III) nature of the isoporphyrins. For the first time, theoretical studies like geometry optimization, simulation of optical spectra, and energy calculations were performed on a methoxy isoporphyrin of simple [FeIII(TPP)Cl] (Iron(III) tetraphenyl porphyrin) using the density functional theory method to understand the typical electronic, redox and highly reactive nature of iron isoporphyrins. The theoretical calculations supported the strong absorptions at the near-IR region in electronic spectra, very reactive nature and typical redox behavior of iron(III) isoporphyrins.

A semi-automated material exploration scheme to predict the solubilities of tetraphenylporphyrin derivatives

Acceleration of material discovery has been tackled by informatics and laboratory automation. Here we show a semi-automated material exploration scheme to modelize the solubility of tetraphenylporphyrin derivatives. The scheme involved the following steps: definition of a practical chemical search space, prioritization of molecules in the space using an extended algorithm for submodular function maximization without requiring biased variable selection or pre-existing data, synthesis & automated measurement, and machine-learning model estimation. The optimal evaluation order selected using the algorithm covered several similar molecules (32% of all targeted molecules, whereas that obtained by random sampling and uncertainty sampling was ~7% and ~4%, respectively) with a small number of evaluations (10 molecules: 0.13% of all targeted molecules). The derived binary classification models predicted ‘good solvents’ with an accuracy >0.8. Overall, we confirmed the effectivity of the proposed semi-automated scheme in early-stage material search projects for accelerating a wider range of material research.

Tetraphenylporphyrin Enters the Ring: First Example of a Complex between Highly Bulky Porphyrins and a Protein.

Tetraphenylporphyrin (TPP) is a symmetrically substituted synthetic porphyrin whose properties can be readily modified, providing it with significant advantages over naturally occurring porphyrins. Herein, we report the first example of a stable complex between a native biomolecule, the haemoprotein HasA, and TPP as well as its derivatives. The X-ray crystal structures of nine different HasA-TPP complexes were solved at high resolutions. HasA capturing TPP derivatives was also demonstrated to inhibit growth of the opportunistic pathogen Pseudomonas aeruginosa. Mutant variants of HasA binding FeTPP were shown to possess a different mode of coordination, permitting the cyclopropanation of styrene.

Coordination and Spectral Properties of Oxa-Substituted Tetraphenylporphyrin Derivatives

Coordination and Spectral Properties of Oxa-Substituted Tetraphenylporphyrin Derivatives

Facile synthesis of antipodal β-arylaminodibromoporphyrins through Buchwald-Hartwig C-N coupling reaction and exploring their spectral and electrochemical redox properties

A new family of antipodal β-arylaminodibromoporphyrins was synthesized through a Buchwald-Hartwing C-N coupling reaction and characterized as to its spectroscopic and electrochemical properties. The investigated compounds are represented as (NHR)Br2TPPM where M = 2H, Cu(II) or Zn(II), (NHR)Br2TPP is the dianion of β-arylaminodibromotetraphenylporphyrin and R is one of the five different aryl groups: Ph, m,m-Me2Ph, NPH = 1-naphthyl, p-CNPh, p-NO2Ph. The yield of desired arylaminoporphyrin depends upon the equivalents of arylamine utilized in the reaction and the electron-donating or electron-withdrawing nature of the R group present on the phenyl ring of the β-arylamino moiety. The Soret bands of these porphyrins are broader and red-shifted as compared to the related tetraphenylporphyrin derivatives, TPPM, whereas their Q bands are intense due to push-pull effects. The emission bands of the free base and Zn(II) derivatives are weak, broad and red-shifted (Δλem = 17-60 nm) as compared to their corresponding TPPM derivatives (M = 2H and Zn) due to the cross-polarized push-pull β-substituents and the heavy atom effect of the two bromo substituents. The (NHR)Br2TPPM complexes exhibit characteristic split NMR signals due to the unsymmetrical β-substitution. The DFT optimized structures indicate a moderate nonplanar porphyrin core, with the Cu(II) arylaminoporphyrins having the largest ∆24 values (average displacement of 24 atoms of macrocyclic core) of 0.595-0.622 Å. The redox properties are also influenced by the electronic nature of the arylamino group with the measured half-wave potentials for reduction being positively shifted by 0.09-0.21 V as compared to the parent TPPM complexes whereas marginal shifts were observed for oxidation processes with respect to the TPPM derivatives. This leads to a 0.14-0.20 V decrease in the electrochemically measured HOMO-LUMO gap for the β-arylaminodibromoporphyrins as compared to the corresponding TPPM analogues.

Syntheses and characteristics of push–pull derivatives for quadruply fused porphyrins

“Push–pull” derivatives (2 – 4) of zinc(II) complexes having quadruply fused porphyrinato (QFP) ligands have been synthesized to elucidate the impact of the “push–pull” effects on the electronic structure of QFP. Each ZnQFP derivative of 2 – 4 has an electron-withdrawing group (EWG) such as nitro group and a methoxy group as an electron-donating group (EDG) at the diagonal positions of the molecule. Owing to the extended [Formula: see text]-conjugation of 2– 4 reaching to the substituted positions of the EWG and EDG, charge-transfer (CT) bands, which are sensitive to the solvent polarity, have been observed in the UV-vis spectra. In contrast, the corresponding “push–pull” derivatives of tetraphenylporphyrin, whose [Formula: see text]-conjugation is disconnected at the bonds between the meso-carbon and meso-aryl group, do not exhibit any CT transitions derived from the substituents.

Supramolecular assemblies of carbon nanocoils and tetraphenylporphyrin derivatives for sensing of catechol and hydroquinone in aqueous solution

Non-enzymatic electrochemical detection of catechol (CC) and hydroquinone (HQ), the xenobiotic pollutants, was carried out at the surface of novel carbon nanocoils/zinc-tetraphenylporphyrin (CNCs/Zn-TPP) nanocomposite supported on glassy carbon electrode. The synergistic effect of chemoresponsive activity of Zn-TPP and a large surface area and electron transfer ability of CNCs lead to efficient detection of CC and HQ. The nanocomposite was characterized by using FT-IR, UV/vis. spectrophotometer, SEM and energy dispersive X-ray spectroscopy (EDS). Cyclic voltammetry, differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy were used for the electrochemical studies. CNCs/Zn-TPP/GCE nanosensor displayed a limit of detection (LOD), limit of quantification (LOQ) and sensitivity for catechol as 0.9 µM, 3.1 µM and 0.48 µA µM−1 cm−2, respectively in a concentration range of 25–1500 µM. Similarly, a linear trend in the concentration of hydroquinone detection was observed between 25 and 1500 µM with an LOD, LOQ and sensitivity of 1.5 µM, 5.1 µM and 0.35 µA µM−1 cm−2, respectively. DPV of binary mixture pictured well resolved peaks with anodic peak potential difference, ∆Epa(CC-HQ), of 110 mV showing efficient sensing of CC and HQ. The developed nanosensor exhibits stability for up to 30 days, better selectivity and good repeatability for eight measurements (4.5% for CC and 5.4% for HQ).

Control Over Protein Multimerization Induced by Water-Soluble Porphyrins

Interactions between charged porphyrins and complimentary or similarly charged proteins provide important models systems for studies of electron transfer processes, artificial photosynthesis, and control of protein-protein interactions. Typically, the experimental results are analyzed and discussed assuming that the proteins exist in a monodisperse state. However, combined small- and wide-angle X-ray scattering experiments revealed the formation of multimers with a wide range of complex sizes. Binding interactions were explored using wild-type and 12 mutants of PpcA, a 3-heme c-type cytochrome from Geobacter sulfurreducens, with several anionic water-soluble derivatives of tetraphenylporphyrin.

Влияние природы мономера на процессы электрополимеризации и физико-химические свойства пленок на основе гидрокси-замещенных тетрафенилпорфиринов

The ability to oxidatively polymerization from a solution in ethanol of tetraphenylporphyrin derivatives: 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin, 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin, Zn-5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin, Zn-5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin were studied. The polymerization of 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin does not occur; three of the four studied porphyrins form thin transparent polyporphyrin films tightly adhered to the electrodes surface. The influence of the nature of the monomer, the deposition mode, and the supporting electrolyte used on the process of electropolymerization and the properties of the deposited polyporphyrin films were studied. The spectral changes observed during the deposition of the films indicate that the generation of the polyporphyrin films occurs through the formation of C–O–C bonds and the keep of the porphyrin macroheterocycle in polyporphyrin.

The quest for a better understanding of ethanol coordination to magnesium and zinc porphyrin: A combined experimental and theoretical study

An ethanol coordinated magnesium porphyrin [Mg(TDMPP)(C2H5OH)], (TDMPP = 5,10,15,20-tetrakis(3,5-dimethoxyphenyl)porphyrin), 1 was synthesized and characterized by single crystal X-ray diffraction method along with other standard spectroscopic techniques. This is the first known crystal structure of an alcohol bound magnesium porphyrin of tetraphenylporphyrin derivatives. Crystal structure of the compound shows a weak hydrogen bonding interaction (2.730(4) Å) between OH group of axial ethanol molecule and a peripheral methoxy group of an adjacent porphyrin molecule. This hydrogen bonding results the formation of a weak one-dimensional supramolecular structure. The fluorescence and electrochemical studies have also been performed. To explore the disadvantages of using zinc porphyrins to study chlorophyll type magnesium porphyrins, a comparison of theoretical study using DFT level was performed between compound [Mg(TDMPP)(C2H5OH)], 1 and its zinc counterpart [Zn(TDMPP)(C2H5OH)], 2. Theoretical calculations include optimization of geometry, energy of frontier molecular orbitals (FMOs), electronic transitions and global chemical indices. The global reactivity indices like η, µ and ω derived from theoretical calculations for zinc and magnesium porphyrin supports that magnesium porphyrin is more reactive than the zinc analogue. Furthermore, the Hirshfeld surface analysis was used to quantify the weak intermolecular interactions present in the crystal lattice of compound 1.

Formation of Highly Ordered Molecular Porous 2D Networks from Cyano-Functionalized Porphyrins on Cu(111).

We investigated the adsorption of three related cyano‐functionalized tetraphenyl porphyrin derivatives on Cu(111) by scanning tunneling microscopy (STM) in ultra‐high vacuum (UHV) with the goal to identify the role of the cyano group and the central Cu atom for the intermolecular and supramolecular arrangement. The porphyrin derivatives studied were Cu‐TCNPP, Cu‐cisDCNPP, and 2H‐cisDCNPP, that is, Cu‐5,10,15,20‐tetrakis‐(p‐cyano)‐phenylporphyrin, Cu‐meso‐cis‐di(p‐cyano)‐phenylporphyrin and 2H‐meso‐cis‐di(p‐cyano)‐phenylporphyrin, respectively. Starting from different structures obtained after deposition at room temperature, all three molecules form the same long‐range ordered hexagonal honeycomb‐type structure with triangular pores and three molecules per unit cell. For the metal‐free 2H‐cisDCNPP, this occurs only after self‐metalation upon heating. The structure‐forming elements are pores with a distance of 3.1 nm, formed by triangles of porphyrins fused together by cyano‐Cu‐cyano interactions with Cu adatoms. This finding leads us to suggest that two cyano‐phenyl groups in the “cis” position is the minimum prerequisite to form a highly ordered 2D porous molecular pattern. The experimental findings are supported by detailed density functional theory calculations to analyze the driving forces that lead to the formation of the porous hexagonal honeycomb‐type structure.

Synthesis and photodynamic antimicrobial activity of amphiphilic meso-arylporphyrins with pyridyl moieties

In this work we report on the synthesis of new cationic pyridyl-containing meso-arylporphyrins and their antimicrobial photodynamic activity against Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria in planktonic and biofilm modes of growth. Received compounds were characterized by EAS, fluorescence, 1H, 13C NMR spectroscopy, liquid chromatography and ESI-MS spectra. Their photophysical (absorbance and fluorescence), photochemical (singlet oxygen generation) properties dark and light-induced toxicity were studied. Aggregation behavior of PSs was investigated in the presence of nonionic solubilizers to identify the most effective nanocarrier. Pluronic F-127 polymer micelles appeared the most suitable nanocontainers for the cationic porphyrins solubilization. The structure/biological activity relationships were evaluated. The influence of aliphatic spacer length on the photochemical and biological properties of tetraphenylporphyrin derivatives was estimated. The inclusion of PSs in polymeric micelles of Pluronic F-127 noticeably increased their photodynamic activity. Our research showed that the proposed porphyrin macrocycle design offers strategies for the efficient photosensitizer modification in the field of antimicrobial photodynamic inactivation.

Aggregation State of Tetraphenylporphyrin Derivatives in Polymer Films Based on Poly-N-Vinylpyrrolidone

The spectral luminescent and electrophysical properties of polymer films based on poly-N-vinylpyrrolidone with the stabilized derivatives of tetraphenylporphyrin in various aggregation states (monomers, J- and H-aggregates) were investigated. Films containing a monomolecular form of porphyrins are characterized by intensive fluorescence. For films with J-aggregates an electric response that was not practically observed in the case of H-aggregates was detected. The films obtained are also characterized by optical and electric response to pH change, particularly in the presence of ammonia and hydrogen chloride vapors. The obtained data allow polymeric films with immobilized porphyrins to be considered as potential material for the creation of film systems for sensor applications, photovoltaics, molecular electronics, and photocatalysis. The variability of the film synthesis methodology allows the aggregation state of the immobilized porphyrins to be changed directionally, which provides the possibility of obtaining films of hybrid organic materials with the desired photophysical properties.

Characterization and Control Over Protein Multimerization Induced by Porphyrins

Interactions between charged porphyrins and complimentary or similarly charged proteins provide important models systems for studies of electron transfer processes, artificial photosynthesis, and control of protein-protein interactions. Typically, the experimental results are analyzed and discussed assuming that the proteins exist in a monodisperse state. However, combined small- and wide-angle X-ray scattering experiments revealed the formation of multimers with a wide range of complex sizes. Binding interactions were explored using wild-type and 12 mutants of PpcA, a 3-heme c-type cytochrome from Geobacter sulfurreducens,with several anionic water-soluble derivatives of tetraphenylporphyrin. Thermodynamic interaction parameters and complex binding stoichiometries were established with isothermal calorimetry.The binding sites of porphyrin were mapped out using HSQC with varying levels of porphyrin concentration to protein. All-atom molecular dynamics simulations revealed quick complex formation with binding sites well matching the areas identified in our experimental work. The obtained results demonstrate that multimerization of solution-state proteins by large water-soluble ligands can be tuned to control shape and size of the formed complexes. Molecular level mapping of the binding sites allows us to build a theory explaining the size of the formed complexes and provides opportunities for targeted design of multi-subunit protein complexes as well as targeted disruption of self-assembled complexes.

Monocationic porphyrin dyads with fullerene as the electron-accepting material

Dyad compounds in which a fullerene [Formula: see text] was covalently linked to a monocationic porphyrin at a N,N[Formula: see text]-bridge substituent, were synthesized by condensation reaction. The low solubility of a dyad containing tetraphenylporphyrin (TPP) derivative was improved by using octaethylporphyrin (OEP) derivatives and introduction of an alkyl substituent to the porphyrin derivatives. The energy levels of the frontier orbitals, estimated experimentally using potentiometric data and the optical energy band gaps obtained by the UV-vis spectra, were sufficiently low to be comparable to acceptor materials. They varied depending on the peripheral substituents on the porphyrin unit. DSC analysis of the drop-cast films of the P3HT/dyad blends showed that the film containing the OEP dyad, annealed at a higher temperature, had more amorphous fractions than the films containing the TPP dyad.

Ferroelectricity of a Tetraphenylporphyrin Derivative Bearing −CONHC14H29 Chains at 500 K

Optical properties of porphyrin derivatives were used to fabricate an artificial light-harvesting system. The introduction of a N–H···O═ hydrogen-bonding alkylamide chain (−CONHCnH2n+1) into a functional π-system is among the useful approaches to design multifunctional supramolecular assemblies. The tetraphenylporphyrin derivative bearing four −CONHC14H29 chains (1) shows the successive and reversible phase transition behavior of S1–S2 at 338 K, S2–Colr at 444 K, and Colr–I (isotropic liquid) at 564 K, where a fluidic discotic rectangular columnar (Colr) liquid crystal phase was observed in a wide temperature range of 444–564 K before melting. The one-dimensional columnar molecular assembly of (1)∞ was constructed using a simultaneous operation of N–H···O═ hydrogen-bonding and π-stacking interactions. Temperature (T)- and frequency (f)-dependent dielectric constants of 1 indicated characteristic dielectric enhancement at higher-T and lower-f conditions above 500 K because of the thermally activated motion...

Poly(photosensitizer) Nanoparticles for Enhanced in Vivo Photodynamic Therapy by Interrupting the π-π Stacking and Extending Circulation Time.

The natural planar and rigid structures of most of the hydrophobic photosensitizers (PSs) [such as tetraphenyl porphyrin (TPP)] significantly reduce their loading efficiencies in polymeric nanoparticles (NPs) because of the strong π-π interaction-induced aggregation. This aggregation-caused quenching will further reduce the quantum yield of singlet oxygen (1O2) generation and weaken the efficiency of photodynamic therapy (PDT). In addition, the small molecular PSs exhibit short tumor retention time and tend to be easily cleared once released. Herein, poly(TPP) NPs, prepared by cross-linking of reactive oxygen species degradable, thioketal linkers and TPP derivatives, followed by coprecipitation, were first developed with quantitative loading efficiency (>99%), uniform NP sizes (without aggregation), increased singlet oxygen quantum yield (ΦΔ = 0.79 in dimethyl sulfoxide compared with 0.52 for original TPP), increased in vitro phototoxicity, extended tumor retention time, light-triggered on-demand release, and enhanced in vivo antitumor efficacy, which comprehensively address the multiple issues for most of the PSs in the PDT area.

Through the challenging synthesis of tetraphenylporphyrin derivatives bearing nitroxide moieties

Tetraphenylporphyrin derivatives a synthetic heterocycles with convenient preparation and a richness of properties which make them attractive in broad fields such as energy, life and materials sciences. Thus, in the quest for new radical architectures, tetraphenylporphyrins are prime candidates. To this end, we designed free-base tetraphenylporphyrins bearing nitronyl and imino nitroxide moieties covalently bonded to the para-position of the meso-phenyl substituent. Their detailed synthesis and characterization are reported here.