Dmitrieva, Olga Andreevna

Kuzmin S.M., Chulovskaya S.A., Dmitrieva O.A., Mamardashvili N.Z., Koifman O.I., Parfenyuk V.I.

• Tetra(3-aminophenyl)porphyrin films were formed via superoxide-assisted method; • Ab initio applies for adsorption energy analysis on the catalytic site; • 3-aminophenyl porphyrin based films show promising ORR activity; • Calculations indicate on the same ORR mechanism as experiments. Polymer films based on 2H-5,10,15,20-tetrakis( 3 -aminophenyl)porphyrin have been successfully prepared by superoxide-assisted electrochemical deposition method from dimethyl sulfoxide solutions. Investigation of the deposition process and obtained films demonstrates typical for superoxide-assisted method mechanism of polymer formation, which leads to phenazine type bridges between porphyrin moieties. The density functional theory method has been used to model a polymer chain fragment and an analysis of natural bond orbital has been carried out. According to the calculations, the charge density distribution on the carbon skeleton of the obtained polymer resembles the distribution of charges on carbon materials doped with nitrogen, which are considered as promising catalysts for the oxygen electroreduction. Thus, the energy of adsorption of O 2 and OOH species (intermediates of oxygen electroreduction) on potential catalytic centers of the model polymer fragment has been calculated. The calculation results indicate predominantly two-electron pathway of O 2 reduction. A catalytic activity of poly-2H-5,10,15,20-tetrakis( 3 -aminophenyl)porphyrin films has been shown for the oxygen electroreduction reaction in an aqueous alkaline medium

Chizhova N.V., Dmitrieva O.A., Mamardashvili N.Z.

In order to obtain perhalogenated metalloporphyrins, exhaustive bromination and chlorination of β-positions of nickel(II) and zinc(II) 5,10,15,20-tetra(2,6-dichlorophenyl)- and 5,10,15,20-tetra(2,6-difluorophenyl)porphyrins with N-bromosuccinimide and N-chlorosuccinimide in dimethylformamide have been carried out. When treating zinc(II) 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetra(2,6-difluorophenyl)porphyrin and zinc(II) 2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetra(2,6-difluorophenyl)porphyrin with trifluoroacetic acid, the corresponding porphyrin ligands have been obtained. The synthesized compounds have been identified by electron absorption, 1H NMR spectroscopy, and mass spectrometry. The structures of halogen-substituted porphyrins and their zinc(II) complexes have been calculated by the DFT method. The introduction of bromine and chlorine atoms into the pyrrole rings of ortho-substituted porphyrins and their metal complexes leads to a distortion of the planar structure of molecules to a saddle-like one. The effect of β-halogenation on the fluorescence quantum yields of the synthesized compounds have been estimated. The quantum yield of β-chlorine-substituted porphyrin decreases by ~7 times as compared to the initial tetra(2,6-difluorophenyl)porphyrin, and that of its zinc porphyrinate decreases by ~15 times as compared to the initial complex. Complete quenching of fluorescence caused by the influence of heavy bromine atoms in the β-positions of the macrocycle is observed for both porphyrins and their metal complexes. Perhalogenated metalloporphyrins have increased n-conductivity and can be used to create new materials exhibiting nonlinear optical and catalytic properties.

Rusanov A.I., Dmitrieva O.A., Mamardashvili N.Z., Tetko I.V.

The development of new functional materials based on porphyrins requires fast and accurate prediction of their spectral properties. The available models in the literature for absorption wavelength and extinction coefficient of the Soret band have low accuracy for this class of compounds. We collected spectral data for porphyrins to extend the literature set and compared the performance of global and local models for their modelling using different machine learning methods. Interestingly, extension of the public database contributed models with lower accuracies compared to the models, which we built using porphyrins only. The later model calculated acceptable RMSE = 2.61 for prediction of the absorption band of 335 porphyrins synthesized in our laboratory, but had a low accuracy (RMSE = 0.52) for extinction coefficient. A development of models using only compounds from our laboratory significantly decreased errors for these compounds (RMSE = 0.5 and 0.042 for absorption band and extinction coefficient, respectively), but limited their applicability only to these homologous series. When developing models, one should clearly keep in mind their potential use and select a strategy that could contribute the most accurate predictions for the target application. The models and data are publicly available.

Dmitrieva O.A., Chizhova N.V., Mamardashvili N.Z.

• Progressive halogenation of fluorophenylporphryins was carried out. • Effect of β -pyrrole substitution on macrocycle fluorescence was estimated. • Materials with photo- and structure-sensitive optical properties were designed. Zn(II)-2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetra-(2,6-difluorophenyl)porphyrin was synthesized by the interaction of Zn(II)-5,10,15,20-tetra-(2,6-difluorophenyl)porphyrin with N -bromosuccinimide in a mixture of chloroform-methanol, chloroform-dimethylformamide and in dimethylformamide. Zn(II)-2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetra-(2,6-difluorophenyl)porphyrin was formed by the reaction of 2,6-difluoro-substituted Zn(II)-porphyrin with N -chlorosuccinimide in the chloroform-methanol mixture and dimethylformamide. Zn(II)-2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetra-(2,3,4,5,6-pentafluorophenyl) porphyrin was synthesized from Zn(II)-5,10,15,20-tetra-(2,3,4,5,6-pentafluorophenyl)porphyrin with an excess of N -chlorosuccinimide via chlorination in dimethylformamide. The corresponding porphyrin-ligands were obtained by treating halogen-substituted zinc porphyrins with trifluoroacetic acid. The synthesized compounds were characterized by UV–Vis, fluorescence, 1 H NMR spectroscopy and mass spectrometry methods. The structures of halogen-substituted porphyrins and their Zn(II) complexes were calculated by the DFT method. The effect of the β-pyrrole halogenation on fluorescence quantum yields of the synthesized compounds was estimated. These halogenated products can be employed for covalent functionalization of the macrocycle pyrrole fragments with the aim of imparting practically important optical, electrochemical and red-ox properties to them.

Dmitrieva O.A., Mamardashvili N.Z.

The photophysics of conjugated metal-linked oligomers of porphyrins has been investigated spectroscopically and by quantum chemical calculations. The influence of the conformation on the ground and first singlet excited states has been studied. The absorption spectra and quantum chemical calculations have revealed two different dimer conformations. The UV–vis spectra calculated by the TD-DFT method are quite comparable with the experimental spectra of the two species. The calculated value of the torsional energy barrier is ΔЕ = 3.4 kJ‧mol−1. Studies of the temperature dependence of the dimer fluorescence spectrum have shown the fundamental possibility of using it as a contactless luminescent temperature sensor. Information about the local temperature can be obtained from the calculated temperature dependence of FIR, which represents a monotonic pseudo-linear trend.

Dmitrieva O.A., Chizhova N.V., Tesakova M.V., Parfenyuk V.I., Mamardashvili N.Z.

• Mono, di, tri and tetra-nitro substituted Mn-porphyrins were synthesized. • Their NBO analysis and structure optimization was performed by DFT method. • Obtained materials electrochemical properties were investigated. • It was shown that nitro substitution determines Mn-porphyrin redox state. Mn(II,III)- and Cd(II)-complexes of 5-mononitro-2,3,7,8,12,13,17,18-octaethylporphyrin, 5,15-dinitro-octaethylporphyrin, 5,10,15-trinitro-2,3,7,8,12,13,17,18-octaethylporphyrin and 5,10,15,20-tetranitro-2,3,7,8,12,13,17,18-octaethylporphyrin have been synthesized and identified. A comparative study of the coordination reactions of the corresponding porphyrin ligands with manganese (II) chloride and metal exchange of their cadmium complexes with manganese (II) chloride in dimethylformamide was carried out to find the optimal conditions for the synthesis of Mn(II, III)-porphyrins. The obtained compounds were identified by UV-vis, 1 H NMR spectroscopy and mass spectrometry. The structural parameters of the synthesized compounds were calculated by the DFT method and their NBO analysis was carried out. The electrochemical properties of the synthesized manganese complexes were studied by the cyclic voltammetry method. It is shown that nitro substitution determines Mn-porphyrin redox state.

Mamardashvili G., Kaigorodova E., Dmitrieva O., Koifman O., Mamardashvili N.

By means of spectrophotometric titration and NMR spectroscopy, the selective binding ability of the Co(III)-5,15-bis-(3-hydroxyphenyl)-10,20-bis-(4-sulfophenyl)porphyrin (Co(III)P1) and Co(III)-5,15-bis-(2-hydroxyphenyl)-10,20-bis-(4-sulfophenyl)porphyrin (Co(III)P2) towards imidazole derivatives of various nature (imidazole (L1), metronidazole (L2), and histamine (L3)) in phosphate buffer (pH 7.4) has been studied. It was found that in the case of L2, L3 the binding of the “first” ligand molecule by porphyrinates Co(III)P1 and Co(III)P2 occurs with the formation of complexes with two binding sites (donor–acceptor bond at the center and hydrogen bond at the periphery of the macrocycle), while the “second” ligand molecule is added to the metalloporphyrin only due to the formation of the donor–acceptor bond at the macrocycle coordination center. The formation of stable complexes with two binding sites has been confirmed by density functional theory method (DFT) quantum chemical calculations and two-dimensional NMR experiments. It was shown that among the studied porphyrinates, Co(III)P2 is more selective towards to L1-L3 ligands, and localization of cobalt porphyrinates in cetylpyridinium chloride (CPC) micelles does not prevent the studied imidazole derivatives reversible binding. The obtained materials can be used to develop effective receptors for recognition, delivery, and prolonged release of drug compounds to the sites of their functioning. Considering that cetylpyridinium chloride is a widely used cationic biocide as a disinfectant, the designed materials may also prove to be effective antimicrobial agents.

Dmitrieva O.A., Ivanova Y.B., Semeikin A.S., Mamardashvili N.Z.

Synthesis and identification of tetrakis-[5,6-bis(4-tert-butylphenyl)pyrazino] porphyrazine, tetra-(4-tert-butyl)phthalocyanine and octakis-(4-tert-butylphenyl)porphyrazine were carried out. Spectrophotometric method was used to study the spectral, acidic and fluorescence properties of the synthesized compounds. It was determined that the synthesized tert-butyl-substituted porphyrazines exhibit a high sensitivity of fluorescence to the molecule ionization. To understand the features of the spectral properties the geometry optimization and an analysis of energy levels and localization of highest occupied and lowest unoccupied molecular orbitals of the studied compounds were performed on the basis of density functional theory with the BP86 functional and the def2-TZVP basis set. The effect of substituents in molecular fragments of the macrocycle on the acidic and electro-optical properties of the studied compounds is revealed. Materials with pH-tunable fluorescence were designed.

Dmitrieva O.A., Koifman M.O., Derbyshina U.M., Chizhova N.V., Mamardashvili N.Z.

Dmitrieva O.A., Chizhova N.V., Rusanov A.I., Koifman M.O., Mamardashvili N.Z.

The original version of this article unfortunately contained a mistake. In the section of ‘Acknowledgements’ the grant number is incorrectly indicated. The corrected grant number is given below.

Ivanova Y.B., Dmitrieva O.A., Khrushkova Y.V., Lyubimova T.V., Semeikin A.S., Mamardashvili N.Z.

Tetrakis{5,6-bis(4-tert-butylphenyl)pyrazino[2,3-c]}porphyrazine and tetra(4-tert-butyl)phthalocyanine have been synthesized, and their acid–base properties and electronic absorption and fluorescence spectra in acetonitrile and toluene at 298 and 295 K, respectively, have been studied. The synthesized compounds have been identified by electronic absorption and1H NMR spectroscopy and mass spectrometry. The effect of substituents in the molecular fragments of the macrocycle on the electronic and optical properties of the synthesized compounds has been estimated.

Dmitrieva O.A., Chizhova N.V., Rusanov A.I., Koifman M.O., Mamardashvili N.Z.

Zn(II)-octa-(4-chlorophenyl)- and Zn(II)-octa-(4-bromophenyl)tetraazaporphyrins were synthesized by the reaction of cyclotetramerization of di-(4-chlorophenyl)- and di-(4-bromophenyl)maleonitriles with zinc(II) chloride. The obtained compounds were identified by UV-vis, IR, NMR 1H spectroscopy and mass spectrometry. Geometry optimization of the series of halogenated Zn(II)-octaaryltetraazaporphyrins was performed using the density functional method with the BP86 functional and the def2-TZVP basis set. An analysis of the distribution of molecular orbital energies in the neighborhood of highest occupied molecular orbitals (HOMO and HOMO-1) and lowest unoccupied molecular orbitals (LUMO and LUMO+1) and the width of the HOMO – LUMO energy gaps (EH-L) was performed for the studied compounds. Fluorimetric measurements of the Zn(II)-octaphenyltetraazaporphyrins in toluene were carried out and fluorescence quantum yields of studied compounds were determined and analyzed. It has been shown that the halogen on the para-position of the phenyl groups significantly affects the value of the obtained quantum yields of fluorescence emission but does not significantly affect the Stokes shifts.

Kruk M.M., Pukhovskaya S.G., Semeykin A.S., Mamardashvili N.Z., Dmitrieva O.A., Ivanova Y.B.

The fluorimetric measurements of the acetonitrile solutions of palladium complexes of the octaethylporphyrin, 5,10- biphenyl octaethylporphyrin and 5,15-biphenyl octaethylporphyrin at 293 K were performed. Tetraphenylporfin was used in toluene as standards. It was determined that the studied compounds differ in the architecture of peripheral substitution, and as a result in molecular conformation and symmetry, which determine the rates of intramolecular processes of deactivation of electronic excitation energy. It was established that the introduction of two phenyl fragments into the meso-positions of the tetrapyrrole macrocycle of the octaethylporphyrin molecule markedly changes the spectral-luminescent properties of their palladium complexes. The compound with the adjacent arrangement of phenyl fragments of 5,10-diphenylctaethylporphyrin is characterized by concentrated steric effects in the region of one quadrant of the macrocycle containing two phenyl groups and the pyrrole fragment located between them. This arrangement of phenyl fragments leads to the formation of an asymmetrically distorted saddle-shaped conformer, as evidenced by the bathochromic shift of the bands in the electronic absorption spectrum by 495 cm–1. The quantum yield of S1→S0 fluorescence decreases slightly to 4.6·10-3, which is explained by the formation of a new competing non-radiative deactivation channel — the internal S1→S0 conversion, which is characteristic of distorted saddle-shaped macrocycle. When phenyl groups at opposite meso-positions of the 5.15-diphenyl octaethylporphyrin macrocycle flanked by alkyl groups in the Cb positions of the pyrrole rings, a conformer is formed with a macrocycle elongated along the Cm-Cm axis. This is probably due to the stricter molecular structure of this conformer compared to palladium octaethylporphyrin and the absence of conformational dynamics in the S1 excited state. As a result, the bathochromic shift of the bands in the electronic absorption spectrum of 5.15 – diphenyl octaethylporphyrin is less than 100 cm-1 and the quantum yield of S1→S0 fluorescence is almost equal to the quantum yield of the palladium complex of octaethylporphyrin - 5.4·10-3, which is probably due to the low non-radiative internal S1→S0 conversion for the 5.15-diphenyl octaethylporphyrin compared to the 5.10-diphenyl octaethylporphyrin.

Sirotkin N.A., Khlyustova A.V., Titov V.A., Krayev A.S., Nikitin D.I., Dmitrieva O.A., Agafonov A.V.

An underwater impulse discharge was used for synthesis tungsten trioxide nanoparticles. The chemical composition and morphology of obtained particles were studied by using X-ray diffraction spectroscopy and electron microscopy. The dynamic light scattering was used to measure the average particle diameter and zeta-potential. It was found that a monoclinic modification of tungsten trioxide was formed with an average particle diameter of about 60 nm. The photocatalytic performance of WO3 was estimated through the degradation of Rhodamine B under dark and UV irradiation conditions. The powder of WO3 exhibited great photocatalytic activity for photodegradation of Rhodamine B of 100% under UV irradiation for 50 min.

Chizhova N.V., Mamardashvili G.M., Dmitrieva O.A., Mamardashvili N.Z., Koifman O.I.

Chizhova N.V., Likhonina A.E., Tesakova M.V., Dmitrieva O.A., Parfenyuk V.I., Mamardashvili N.Z.

Kaigorodova E.Y., Mamardashvili G.M., Mamardashvili N.Z.

Madkhli A.Y., Alharbe L.G.

Xiang Y., Yu H., Wu K., Quan Z., He D., Ou C., Chai X., Liang Y., Duan X., Zhang X., Zha Q., Xie W.

A smartphone-based non-invasive method was developed for salivary uric acid detection using Gleditsia Sinensis carbon dots (GS-CDs). The GS-CDs synthesized by the one-pot hydrothermal method emitted blue fluorescence at a maximum excitation wavelength of 350 nm and had good fluorescence stability in the presence of different ions, while showing selectivity to uric acid solution. The ability of uric acid (UA) to quench the fluorescent substances present in the GS-CDs, was confirmed through HPLC-FLD and LC–MS, FTIR and XPS. The results showed that UA reacted with GS-CDs, with a decrease in hydroxyl groups and the formation of carboxyl groups. The fluorescence quenching suggested a possible dynamic quenching mechanism. In addition, a smartphone-based non-invasive detection method was developed for the detection of salivary UA levels, which reflects blood UA levels. This study provides a new perspective on the utilization of GS shells and advances the development of non-invasive testing for UA.

Wang X., Wu H., Wang T., Chen Y., Jia B., Fang H., Yin X., Zhao Y., Yu R.

Vigna V., Cova T.F., Pais A.A., Sicilia E.

Effective light-based cancer treatments, such as photodynamic therapy (PDT) and photoactivated chemotherapy (PACT), rely on compounds that are activated by light efficiently, and absorb within the therapeutic window (600–850 nm). Traditional prediction methods for these light absorption properties, including Time-Dependent Density Functional Theory (TDDFT), are often computationally intensive and time-consuming. In this study, we explore a machine learning (ML) approach to predict the light absorption in the region of the therapeutic window of platinum, iridium, ruthenium, and rhodium complexes, aiming at streamlining the screening of potential photoactivatable prodrugs. By compiling a dataset of 9775 complexes from the Reaxys database, we trained six classification models, including random forests, support vector machines, and neural networks, utilizing various molecular descriptors. Our findings indicate that the Extreme Gradient Boosting Classifier (XGBC) paired with AtomPairs2D descriptors delivers the highest predictive accuracy and robustness. This ML-based method significantly accelerates the identification of suitable compounds, providing a valuable tool for the early-stage design and development of phototherapy drugs. The method also allows to change relevant structural characteristics of a base molecule using information from the supervised approach. Scientific Contribution: The proposed machine learning (ML) approach predicts the ability of transition metal-based complexes to absorb light in the UV–vis therapeutic window, a key trait for phototherapeutic agents. While ML models have been used to predict UV–vis properties of organic molecules, applying this to metal complexes is novel. The model is efficient, fast, and resource-light, using decision tree-based algorithms that provide interpretable results. This interpretability helps to understand classification rules and facilitates targeted structural modifications to convert inactive complexes into potentially active ones.

Alfadhli S., Khasim S., Darwish A.A., Al-nahdi K., Abdelkader M., Gamal R., Hamdalla T.A.

Krishna Das G., Nayak S., Bhattacharya S., Banerjee S., Paul S., Bhattacharya S.

Supramolecular interaction of N-methylfulleropyrrolidine (A) with a free-base porphyrazine (H2Pz) is investigated in toluene. The interaction between A and H2Pz is favored by charge transfer (CT), as the CT absorption band for the A-H2Pz system is located at 533 nm. Utilizing the CT absorption maxima, some important physicochemical parameters are evaluated in the present work. The binding constant (K) of the A-H2Pz system is determined both from UV-vis (KUV-vis = 29640 dm3· mol−1) and steady-state fluorescence measurements (Kfluorescence = 15440 dm3 · mol−1). Lifetime measurement measures the value of the rate constant of charge separation and quantum yield of charge separation of the A-H2Pz system, which supports the rationale of CT at the ground state. Hybrid-DFT calculations by the B3LYP method, extend very good support in favor of the K value of the A-H2Pz system in terms of the heat of formation value, i.e., 0.57 kcal · mol−1, and it provides excellent corroboration between the experimentally obtained CT energy (i.e., 2.325 eV) and the theoretically obtained EHOMO – ELUMO value of the A-H2Pz system (EHOMO – ELUMO = 2.330 eV). The present study envisages that H2Pz may be suitably employed as an effective receptor for functionalized fullerene molecules in the near future.

Mamedov T., Shvirst A., Fedotova M.V., Chuev G.N.

Noncontact atomic force microscopy, a type of scanning probe microscopy, has been actively used in the last two decades to study hydrated biomolecules. Analysis of modern literature shows that noncontact atomic force microscopy is a very promising method for studying adsorbed biomacromolecules and biomacromolecular complexes at the membrane interface or surfaces. This mini-review describes the foundations of this method, its application to biomolecules, discusses the requirements for the method and the possibility of its extension through additional processing of the obtained experimental data using theoretical analysis, molecular modeling or machine learning.

Mamardashvili G., Kaigorodova E., Solomonova N., Mamardashvili N.

Zvezdina S.V., Chizhova N.V., Mamardashvili N.Z.

The exhaustive halogenation of the β-positions of Cu(II)-5,10,15,20-tetra-(2,6-difluorophenyl)porphyrin using N-bromosuccinimide and N-chlorosuccinimide in dimethylformamide was carried out. Cu(II)-β-octachloro-(2,3,4,5,6-pentafluorophenyl)porphyrin was synthesized by the reaction of Cu(II)-5,10,15,20-tetra-(2,3,4,5,6-pentafluorophenyl)porphyrin with N-chlorosuccinimide in dimethylformamide. Using the complexation of β-octabromo-5,10,15,20-tetra-(2,6-difluorophenyl)porphyrin, β-octachloro-5,10,15,20-tetra-(2,6-difluorophenyl)porphyrin, and β-octachloro-5,10,15,20-tetra-(2,3,4,5,6-pentafluorophenyl)porphyrin with copper salts in dimethylformamide under mild conditions, the corresponding copper(II) complexes were obtained. The coordination reaction kinetics of β-octabromo-5,10,15,20-tetra-(2,6-difluorophenyl-porphyrin with copper chloride in dimethylformamide has been studied. The kinetic parameters of the reaction were calculated. The obtained compounds were identified by UV-Vis and 1H NMR spectroscopies, mass spectrometry, and elemental analysis. X-ray powder diffraction patterns were obtained for a number of copper complexes.

Wang B., Jia W., Liu M., Zhang Z., Shan Q., Hei D., Liao M., Chu Y., Ling Y., Lu Q., Yu J.

Ullal N., Sahoo B., Sunil D., Kulkarni S.D., Sinha R.K., Anand P.J., Udaya B.K.

Sirotkin N., Khlyustova A., Titov V., Naumova I., Kicheeva T., Khizhkina M., Agafonov A.

Ovchenkova E.N., Lomova T.N.

Knowledge of the parameters and mechanisms of proton transfer from the medium to the macrocyclic ligand in complexes of highly substituted phthalocyanines is necessary for optimization of technological processes of catalysis and design of functional materials. Octakis(3,5-di-tert-butylphenoxy)phthalocyanine complexes with 3d-metal ions have been synthesized, and their acid–base reactions have been studied by UV-vis and 1H NMR spectroscopy. The chemical structure of the complexes has been determined using elemental analysis, MALDI-TOF mass spectrometry, IR, 1H NMR, and UV-vis spectroscopy data. Complete protonation of the Co, Ni, and Cu complexes takes place in dichloromethane–trifluoroacetic acid mixtures. Doubly and quadruply protonated forms have been identified in UV-vis spectra. The concentration ranges of existence, UV-vis parameters, and the thermodynamic stability constants of the protonated forms, as well as their relationship with the electronic structure of the coordination center, have been determined.

Li X., Lei H., Xie L., Wang N., Zhang W., Cao R.

The hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) are involved in biological and artificial energy conversions. H-H and O-O bond formation/cleavage are essential steps in these reactions. In nature, intermediates involved in the H-H and O-O bond formation/cleavage are highly reactive and short-lived, making their identification and investigation difficult. In artificial catalysis, the realization of these reactions at considerable rates and close to their thermodynamic reaction equilibria remains a challenge. Therefore, the elucidation of the reaction mechanisms and structure-function relationships is of fundamental significance to understand these reactions and to develop catalysts.This Account describes our recent investigations on catalytic HER, OER, and ORR with metalloporphyrins and derivatives. Metalloporphyrins are used in nature for light harvesting, energy conversion, electron transfer, O2 activation, and peroxide degradation. Synthetic metal porphyrin complexes are shown to be active for these reactions. We focused on exploring metalloporphyrins to study reaction mechanisms and structure-function relationships because they have stable and tunable structures and characteristic spectroscopic properties.For HER, we identified three H-H bond formation mechanisms and established the correlation between these processes and metal hydride electronic structures. Importantly, we provided direct experimental evidence for the bimetallic homolytic H-H bond formation mechanism by using sterically bulky porphyrins. Homolytic HER has been long proposed but rarely verified because the coupling of active hydride intermediates occurs spontaneously and quickly, making their detection challenging. By blocking the bimolecular mechanism through steric effects, we stabilized and characterized the NiIII-H intermediate and verified homolytic HER by comparing the reaction behaviors of Ni porphyrins with and without steric effects. We therefore provided an unprecedented example to control homolytic versus heterolytic HER mechanisms through tuning steric effects of molecular catalysts.For the OER, the water nucleophilic attack (WNA) on high-valent terminal Mn-oxo has been proposed for the O-O bond formation in natural and artificial water oxidation. By using Mn tris(pentafluorophenyl)corrole, we identified MnV(O) and MnIV-peroxo intermediates in chemical and electrochemical OER and provided direct experimental evidence for the Mn-based WNA mechanism. Moreover, we demonstrated several catalyst design strategies to enhance the WNA rate, including the pioneering use of protective axial ligands. By studying Cu porphyrins, we proposed a bimolecular coupling mechanism between two metal-hydroxide radicals to form O-O bonds. Note that late-transition metals do not likely form terminal metal-oxo/oxyl.For the ORR, we presented several strategies to improve activity and selectivity, including providing rapid electron transfer, using electron-donating axial ligands, introducing hydrogen-bonding interactions, constructing dinuclear cooperation, and employing porphyrin-support domino catalysis. Importantly, we used Co porphyrin atropisomers to realize both two-electron and four-electron ORR, representing an unparalleled example to control ORR selectivity by tuning only steric effects without modifying molecular and/or electronic structures.Lastly, we developed several strategies to graft metalloporphyrins on various electrode materials through different covalent bonds. The molecular-engineered materials exhibit boosted electrocatalytic performance, highlighting promising applications of molecular electrocatalysis. Taken together, this Account demonstrates the benefits of exploring metalloporphyrins for the HER, OER, and ORR. The knowledge learned herein is valuable for the development of porphyrin-based catalysts and also other molecular and material catalysts for small molecule activation reactions.

Ksenofontov A.A., Lukanov M.M., Bocharov P.S., Berezin M.B., Tetko I.V.

A possibility to accurately predict the absorption maximum wavelength of BODIPYs was investigated. We found that previously reported models had a low accuracy (40-57 nm) to predict BODIPYs due to the limited dataset sizes and/or number of BODIPYs (few hundreds). New models developed in this study were based on data of 6000-plus fluorescent dyes (including 4000-plus BODIPYs) and the deep neural network architecture. The high prediction accuracy (five-fold cross-validation room mean squared error (RMSE) of 18.4 nm) was obtained using a consensus model, which was more accurate than individual models. This model provided the excellent accuracy (RMSE of 8 nm) for molecules previously synthesized in our laboratory as well as for prospective validation of three new BODIPYs. We found that solvent properties did not significantly influence the model accuracy since only few BODIPYs exhibited solvatochromism. The analysis of large prediction errors suggested that compounds able to have intermolecular interactions with solvent or salts were likely to be incorrectly predicted. The consensus model is freely available at https://ochem.eu/article/134921 and can help the other researchers to accelerate design of new dyes with desired properties.

Chemically functionalized single-walled carbon nanotubes (SWNTs) have shown promise in tumor targeted accumulation in mice and exhibit biocompatibility, excretion and little toxicity. Here, we demonstrate in-vivo SWNT drug delivery for tumor suppression in mice. We conjugate paclitaxel (PTX), a widely used cancer chemotherapy drug to branched polyethylene-glycol (PEG) chains on SWNTs via a cleavable ester bond to obtain a water soluble SWNT-paclitaxel conjugate (SWNT-PTX). SWNT-PTX affords higher efficacy in suppressing tumor growth than clinical Taxol in a murine 4T1 breast-cancer model, owing to prolonged blood circulation and 10-fold higher tumor PTX uptake by SWNT delivery likely through enhanced permeability and retention (EPR). Drug molecules carried into the reticuloendothelial system are released from SWNTs and excreted via biliary pathway without causing obvious toxic effects to normal organs. Thus, nanotube drug delivery is promising for high treatment efficacy and minimum side effects for future cancer therapy with low drug doses.

Zhong M., Liu M., Li N., Bu X.

In this review, recent advances and perspectives of MOFs and COFs in metal–air batteries were summarized, and some important issues as well as the recommended solutions in future are also described. Metal-air batteries (MABs) have attracted considerable attention as a novel energy technology that can alleviate the severe energy crisis and environmental pollution. Two primary processes, including oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) occur on the air cathode and dominate the battery performance during battery charging and discharging. Recently, metal–organic frameworks (MOFs) and covalent–organic frameworks (COFs) emerge as promising cathode catalysts due to their structure and composition superiority. The unique characteristics of MOFs and COFs contribute to improved performance. This review mainly summarizes the recent applications of MOFs and COFs in a series of MABs, mainly including lithium- and zinc-air batteries. Additionally, some critical issues are emphasized regarding MOFs and COFs used in other MABs limited progress, their fabrication and alternatives to potential problems.

Ghosh D., Koch U., Hadian K., Sattler M., Tetko I.V.

AlphaScreen is one of the most widely used assay technologies in drug discovery due to its versatility, dynamic range and sensitivity. However, a presence of false positives and frequent hitters contributes to difficulties with an interpretation of measured HTS data. Although filters do exist to identify frequent hitters for AlphaScreen, they are frequently based on privileged scaffolds. The development of such filters is time consuming and requires deep domain knowledge. Recently, machine learning and artificial intelligence methods are emerging as important tools to advance drug discovery and chemoinformatics, including their application to identification of frequent hitters in screening assays. However, the relative performance and complementarity of the Machine Learning and scaffold-based techniques has not yet been comprehensively compared. In this study, we analysed filters based on the privileged scaffolds with filters built using machine learning. Our results demonstrate that machine-learning methods provide more accurate filters for identification of frequent hitters in AlphaScreen assays than scaffold-based methods and can be easily redeveloped once new data are measured. We present highly accurate models to identify frequent hitters in AlphaScreen assays.

Mamardashvili G., Mamardashvili N., Koifman O.

Molecular recognition of host/guest molecules represents the basis of many biological processes and phenomena. Enzymatic catalysis and inhibition, immunological response, reproduction of genetic information, biological regulatory functions, the effects of drugs, and ion transfer—all these processes include the stage of structure recognition during complexation. The goal of this review is to solicit and publish the latest advances in the design and sensing and binding abilities of porphyrin-based heterotopic receptors with well-defined geometries, the recognition ability of which is realized due to ionic, H-bridge, charge transfer, hydrophobic, and hydrophilic interactions. The dissection of the considered low-energy processes at the molecular scale expands our capabilities in the development of effective systems for controlled recognition, selective delivery, and prolonged release of substrates of different natures (including drugs) to their sites of functioning.

Lv B., Li X., Guo K., Ma J., Wang Y., Lei H., Wang F., Jin X., Zhang Q., Zhang W., Long R., Xiong Y., Apfel U., Cao R.

Achieving a selective 2 e- or 4 e- oxygen reduction reaction (ORR) is critical but challenging. Herein, we report controlling ORR selectivity of Co porphyrins by tuning only steric effects. We designed Co porphyrin 1 with meso-phenyls each bearing a bulky ortho-amido group. Due to the resulted steric hinderance, 1 has four atropisomers with similar electronic structures but dissimilar steric effects. Isomers αβαβ and αααα catalyze ORR with n=2.10 and 3.75 (n is the electron number transferred per O2 ), respectively, but ααββ and αααβ show poor selectivity with n=2.89-3.10. Isomer αβαβ catalyzes 2 e- ORR by preventing a bimolecular O2 activation path, while αααα improves 4 e- ORR selectivity by improving O2 binding at its pocket, a feature confirmed by spectroscopy methods, including O K-edge near-edge X-ray absorption fine structure. This work represents an unparalleled example to improve 2 e- and 4 e- ORR by tuning only steric effects without changing molecular and electronic structures.

Joung J.F., Han M., Hwang J., Jeong M., Choi D.H., Park S.

Accurate and reliable prediction of the optical and photophysical properties of organic compounds is important in various research fields. Here, we developed deep learning (DL) optical spectroscopy using a DL model and experimental database to predict seven optical and photophysical properties of organic compounds, namely, the absorption peak position and bandwidth, extinction coefficient, emission peak position and bandwidth, photoluminescence quantum yield (PLQY), and emission lifetime. Our DL model included the chromophore–solvent interaction to account for the effect of local environments on the optical and photophysical properties of organic compounds and was trained using an experimental database of 30 094 chromophore/solvent combinations. Our DL optical spectroscopy made it possible to reliably and quickly predict the aforementioned properties of organic compounds in solution, gas phase, film, and powder with the root mean squared errors of 26.6 and 28.0 nm for absorption and emission peak positions, 603 and 532 cm–1 for absorption and emission bandwidths, and 0.209, 0.371, and 0.262 for the logarithm of the extinction coefficient, PLQY, and emission lifetime, respectively. Finally, we demonstrated how a blue emitter with desired optical and photophysical properties could be efficiently virtually screened and developed by DL optical spectroscopy. DL optical spectroscopy can be efficiently used for developing chromophores and fluorophores in various research areas.

Liang Z., Guo H., Zhou G., Guo K., Wang B., Lei H., Zhang W., Zheng H., Apfel U., Cao R.

Synthesizing molecule@support hybrids is appealing to improve molecular electrocatalysis. We report herein metal-organic framework (MOF)-supported Co porphyrins for the oxygen reduction reaction (ORR) with improved activity and selectivity. Co porphyrins can be grafted on MOF surfaces through ligand exchange. A variety of porphyrin@MOF hybrids were made using this method. Grafted Co porphyrins showed boosted ORR activity with large (>70 mV) anodic shift of the half-wave potential compared to ungrafted porphyrins. By using active MOFs for peroxide reduction, the number of electrons transferred per O2 increased from 2.65 to 3.70, showing significantly improved selectivity for the 4e ORR. It is demonstrated that H2 O2 generated from O2 reduction at Co porphyrins is further reduced at MOF surfaces, leading to improved 4e ORR. As a practical demonstration, these hybrids were used as air electrode catalysts in Zn-air batteries, which exhibited equal performance to that with Pt-based materials.

Xie L., Zhang X., Zhao B., Li P., Qi J., Guo X., Wang B., Lei H., Zhang W., Apfel U., Cao R.

Nature uses Fe porphyrin sites for the oxygen reduction reaction (ORR). Synthetic Fe porphyrins have been extensively studied as ORR catalysts, but activity improvement is required. On the other hand, Fe porphyrins have been rarely shown to be efficient for the oxygen evolution reaction (OER). We herein report an enzyme-inspired Fe porphyrin 1 as an efficient catalyst for both ORR and OER. Complex 1, which bears a tethered imidazole for Fe binding, beats imidazole-free analogue 2, with an anodic shift of ORR half-wave potential by 160 mV and a decrease of OER overpotential by 150 mV to get the benchmark current density at 10 mA cm−2. Theoretical studies suggested that hydroxide attack to a formal FeV=O form the O−O bond. The axial imidazole can prevent the formation of trans HO-FeV=O, which is less effective to form O−O bond with hydroxide. As a practical demonstration, we assembled rechargeable Zn-air battery with 1, which shows equal performance to that with Pt/Ir-based materials.

Kuzmin S.M., Chulovskaya S.A., Parfenyuk V.I., Koifman O.I.

Superoxide-initiated anion-radical electrodeposition from solutions in DMSO was used to obtain smooth compact films of poly-5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin having a photovoltaic response.

Sallam G., Shaban S.Y., Nassar A., El-Khouly M.E.

Here we report the photophysical and sensing properties of the aqueous solution of meso-tetra(N-methyl-4-pyridyl)porphyrin toluene sulfonate (TMPP) for simultaneous detection of toxic metal ions in an aqueous medium by using different physiochemical methods such as UV-vis absorption, steady state and time resolved fluorescence, stopped flow, and cyclic voltammetry. The steady-state absorption and fluorescence spectra in organic solvents (EtOH, DMSO, DMF, MeOH and ACN) showed the formation of monomer form (λmaxabs = 426 nm and λmaxflu = 654 and 715 nm). In THF and water, different spectral features were recorded suggested the formation of aggregated forms in both solvents. The formation of aggregated form in water was confirmed by recording the remarkable fluorescence quenching of the singlet excited TMPP with increasing the concentrations of TMPP. In cationic micelles (CTAB), both the absorption and fluorescence spectra were significantly decreased with increasing the concentrations of CTAB with a break at CMC value at 6.0 × 10-5 M. In an anionic micelle (SDS), the CMC value was found to be 1.0 × 10-4 M. Upon interacting with different metal ions, the absorption and fluorescence spectra of TMPP showed different features depending on the metal ions. While the optical studies of TMPP showed no significant interaction in the presence of Mn+2, Co+2, Ba2+, and Ni+2, TMPP showed that it can function as a single optical chemical sensor for the toxic metal ions in water, particularly Hg+2, Pb+2, Cu+2, and Cd+2 ions.

Lazovskiy D.A., Mamardashvili G.M., Khodov I.A., Mamardashvili N.Z.

This paper reports the results of the synthesis and identification of water soluble trans-diaxial complexes of Sn(IV)-5,10,15,20-tetra-(4-sulfophenyl)porphyrin with fluorescein, in which the organic ligands are bound to the tin cation of the tetrapyrrolic macrocycle via a carboxyl (triad I) or a hydroxyl (triad II) group. The structures of triads (I, II) were confirmed by the methods of one- and two-dimensional NMR and quantum-chemical modeling. A spectrophotometric method was used to study the spectral, acidic and fluorescence properties of the synthesized compounds. The paper also discusses the possible mechanisms of protolytic and tautomeric equilibria in the processes involving fluorescein ligands in the axial complexes with hydrophilic Sn(IV)porphyrin. It is found that the fractional distribution of the triads with the lactone, quinoid, and zwitterionic forms of fluorescein axial ligands depends on the medium acidity, exhibiting high pH sensitivity in the ranges where this substance and its derivatives in the free state do not exhibit fluorescence. As a result, the ability of the porphyrin-fluorescein triads to determine water acidity can be used to develop an effective method of detecting pH-dependent biological processes and environmental pollution. This method will facilitate the production of new fluorescent sensors for biomedical purposes (drug delivery triggered by pH changes or oxygen distribution in tissues) and engineering applications (wastewater detection).

Mamardashvili G.M., Kaigorodova E.Y., Simonova O.R., Lazovskiy D.A., Mamardashvili N.Z.

Processes of anionic Sn(IV)-tetra(4-sulfonatophenyl)porphyrin axial complexes with three different ligands (hydroxyl, methoxidol and tyrosine) inclusion in an oppositely charged surfactant in a phosphate buffer at 25 °C were studied. It was shown how the association and localization of the porphyrins into spherical cetyltrimethylammonium bromide micelles affect the aggregation, micelle formation, fluorescent properties and photochemical stability of the systems formed depending on the nature of the Sn(IV)-porphyrin axial ligands. The results obtained determine conditions for quenching or enhancement the fluorescence of the hydrophilic Sn(IV)-porphyrin complexes while reducing the possibility of their photochemical destruction and can be useful in the design of new types of photosensitizers for PDT. • Processes of anionic Sn-porphyrins interaction with cationic surfactant were studied. • Porphyrin localization into micelle affects fluorescent properties and photochemical stability. • Systems with improved fluorescence and photo-stability were designed.

Longevial J., Miyagawa K., Shinokubo H.

An AuBr3/AgOTf combination achieves site-selective bromination on the mesityl substituents of 10,20-dimesityl-5,15-diazaporphyrins.