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Aim: Recent research shows that 3CLpro enzyme of SARS-CoV-2 is a significant target against COVID-19. Drug modeling allows the design of inhibitors of 3CLpro, but the accuracy of those methods remains unclear. Therefore, it is important to determine the trustworthiness of the designed ligand–receptor complexes. Method & materials: The authors built models for the reliability evaluation of 3CLpro complexes with ligands using an in-house developed AlteQ approach and complementarity principles. The models were based on 145 experimentally found 3CLpro complexes with ligands for five different binding sites. Result & conclusion: The obtained models correspond to linear regression with high values of correlation coefficients and can be successfully used to determine the reliability of the docked 3CLpro complexes with ligands.

The“RAS-RAF-MEK-ERK” pathway is an important signaling pathway in melanoma. BRAFV600E(70–90%) is the most common mutation in this pathway. BRAF inhibitors have four types of conformers: type I (aC-IN/DFG-IN), type II (aC-IN/DFG-OUT), type I1/2(aC-OUT/DFG-IN), and type I/II (aC-OUT/DFG-OUT). First-and second-generation BRAF inhibitors show resistance to BRAFV600Eand are ineffective against malignancies induced by dimer BRAF mutants causing ‘paradoxical’ activation. In the present study, we performed molecular modeling of pyrimidine–sulfonamide hybrids inhibitors using 3D-QSAR, molecular docking, and molecular dynamics simulations. Previous reports reveal the importance of pyrimidine and sulfonamide moieties in the development of BRAFV600E inhibitors. Analysis of 3D-QSAR models provided novel pyrimidine sulfonamide hybrid BRAFV600E inhibitors. The designed compounds share similarities with several structural moieties present in first- and second-generation BRAF inhibitors. A total library of 88 designed compounds was generated and molecular docking studies were performed with them. Four molecules (T109, T183, T160, and T126) were identified as hits and selected for detailed studies. Molecular dynamics simulations were performed at 900 ns and binding was calculated. Based on molecular docking and simulation studies, it was found that the designed compounds have better interactions with the core active site [the nucleotide (ADP or ATP) binding site, DFG motif, and the phospho-acceptor site (activation segment) of BRAFV600E protein than previous inhibitors. Similar to the FDA-approved BRAFV600E inhibitors the developed compounds have [aC-OUT/DFG-IN] conformation. Compounds T126, T160 and T183 interacted with DIF (Leu505), making them potentially useful against BRAFV600E resistance and malignancies induced by dimer BRAF mutants. The synthesis and biological evaluation of the designed molecules is in progress, which may lead to some potent BRAFV600E selective inhibitors.

We optimized a solvent-free mechanochemical grinding procedure for the synthesis of N-substituted amines. The method involves mild reaction conditions and isolation of products without column chromatography.

Human thymidylate synthase is the rate-limiting enzyme in the de novo synthesis of 2'-deoxythymidine-5'-monophosphate. dUMP (pyrimidine) and folate binding site hTS inhibitors showed resistance in colorectal cancer (CRC). In the present study, we have performed virtual screening of the pyrido[2,3-d]pyrimidine database, followed by binding free energy calculations, and pharmacophore mapping to design novel pyrido[2,3-d]pyrimidine derivatives to stabilize inactive confirmation of hTS. A library of 42 molecules was designed. Based on the molecular docking studies, four ligands (T36, T39, T40, and T13) were identified to have better interactions and docking scores with the catalytic sites [dUMP (pyrimidine) and folate binding sites] of hTS protein than standard drug, raltitrexed. To validate efficacy of the designed molecules, we performed molecular dynamics simulation studies at 1000 ns with principal component analysis and binding free energy calculations on the hTS protein, also drug likeness properties of all hits were in acceptable range. Compounds T36, T39, T40, and T13 interacted with the catalytic amino acid (Cys195), an essential amino acid for anticancer activity. The designed molecules stabilized the inactive conformation of hTS, resulting in the inhibition of hTS. The designed compounds will undergo synthesis and biological evaluation, which may yield selective, less toxic, and highly potent hTS inhibitors. Communicated by Ramaswamy H. Sarma

Considering the vast importance of peptide and protein interactions with inorganic surfaces, probing hydrogen bonding during their adsorption on metal oxide surfaces is a relevant task that could shed light on the essential features of their interplay. This work is devoted to studying the dipeptides' adsorption on anatase nanoparticles (ANs) in light and heavy water to reveal differences arising upon the change of the major hydrogen bonding carrier. Thermodynamic study of six native dipeptides' adsorption on ANs in both media shows a strong influence of the solvent on the Gibbs free energy and the effect of side-chain mobile protons on the entropy of the process. The adsorption is endothermic irrespective of the medium and is entropy-driven. Computer simulations of peptide adsorption in both media shows similarity in binding via an amino group and demonstrates structural features of protonated and deuterated peptides in obtained complexes. Calculated peptide- anatase nanoparticle (AN) descriptors indicate surface oxygens as points of peptide-nanoparticle contacts.

We report a series of hybrid oxoazetidine conjugated thiazoles as epidermal growth factor receptor (EGFR) inhibitors, which were synthesized and tested using a variety of in silico and in vitro studies. The compounds were found to be active against breast and hepatic cancer cell lines, with Compounds 7a, 7b, and 7e being the most potent ones. The derivatives were also evaluated for molecular docking and complementarity studies to explicate fundamental substituent groups essential for their bioactivity. Moreover, the structural activity relationship of the analogues was performed for future compound optimization. These studies advocated that the analogues have a high affinity towards EGFR with favorable anticancer potential. The study advised that the derivatives have potency against breast and hepatic cancer and can assist as an initial scaffold for further development of anti-EGFR compounds.

Diabetes mellitus is a typical life threatening of disease, which generate due to the dysfunction of β cells of pancreas. In 2014, WHO stated that 422 million people were infected with DM. The current pattern of management of diabetes included synthetic or plant based oral hypoglycemic drugs and insulin but drug resentence is become a very big issues in antidiabetic therapy. Thus, it's very earnest to discover now medication for this disease. Now the days, it is well acknowledged that diabetic patients are more prone towards covid and related complications. Thus, medical practitioners reformed the methodology of prescribing medication for covid infected antidiabetic therapy and encouraging the medication contains dual pharmacological properties. It is also well know that polyphenols specifically hold a significant role in oxidative stress and reduced the severity of many inflammatory diseases. Cucumis melo has rich history as ethano-pharmacological use in Indian subcontinent. The fruit and seed are well-known for the treatment of various diseases due to the presence of phenolics. Therefore, in this study, the combined mixture of flower and seeds were used for the extraction of polyphenolic rich extract and tested for antidiabetic activity through the antioxidant and in vivo experiments. The antioxidant potential measurement exhibited that the selected plant extract has the significant competence to down-regulate oxidative stress (DPPH scavenging IC

The SARS-CoV-2 3CL protease (3CLpro) shows a high similarity with 3CL proteases of other beta-coronaviruses, such as SARS and MERS. It is the main enzyme involved in generating various non-structural proteins that are important for viral replication and is one of the most important proteins responsible for SARS-CoV-2 virulence. In this study, we have conducted an ensemble docking of molecules from the DrugBank database using both the crystallographic structure of the SARS-CoV-2 3CLpro, as well as five conformations obtained after performing a cluster analysis of a 300 ns molecular dynamics (MD) simulation. This procedure elucidated the inappropriateness of the active site for non-covalent inhibitors, but it has also shown that there exists an additional, more favorable, allosteric binding site, which could be a better target for non-covalent inhibitors, as it could prevent dimerization and activation of SARS-CoV-2 3CLpro. Two such examples are radotinib and nilotinib, tyrosine kinase inhibitors already in use for treatment of leukemia and which binding to the newly found allosteric binding site was also confirmed using MD simulations. Communicated by Ramaswamy H. Sarma, Graphical Abstract

The complementarity principle is a well-established concept in the field of chemistry and biology. This concept is widely studied as the lock-and-key relationship between two structures, such as enzyme and ligand interactions. These interactions are based on the overlap of electron clouds between two structures. In this study, a mathematical relation determining complementarity of intermolecular contacts in terms of overlaps of electron clouds was examined using a quantum orbital-free AlteQ method developed in-house for 64 EGFR–ligand complexes with experimentally measured binding affinity data. A very high correlation was found between the overlap of ligand and enzyme electron clouds and the calculated terms, providing a good basis for prognosis of bioactivity and for molecular docking studies.

Aims:: The aim of this letter is to explore the influence of adding hydrogen atoms to the crystallographic structures of HIV-1 protease complexes with a series of inhibitors on the performance of radial distribution function based descriptors recently introduced in chemoinformatic studies. Background:: Quite recently the successful application of molecular descriptors based on a radial distribution function to correlate it with biologically interesting properties of a ligand – enzyme complex was demonstrated. Except its predictive power, the analysis of atoms with dominant contributions to the RDFs can be used to identify relevant atoms and interactions. Since original paper was published on dataset consisting of the X-ray structures of complexes without hydrogen atoms, we wonder weather addition of light atoms can provide us new piece of information. Objective:: The primarily objective is to create the model correlating the RDF based descriptors and physicochemical properties of the HIV-1 protease complexes with inhibitors with hydrogen atoms. Then, we will compare the performance of new model with previous one, where the hydrogen atoms were discarded. Information about interactions between the enzyme and the inhibitors will be extracted from the analysis of the RDF. Methods:: The radial distribution function descriptor weighted by the number of valence shell electrons has proven to be sensitive to the changes in the structure of the enzyme and enzyme-ligand complexes. For each structure in our data set, RDF will be calculated and using multiple linear regression method the mathematical model will be designed correlating RDF based descriptors and the physicochemical properties. Statistical analysis of the atom’s contribution to the total RDF will reveal relevant interactions. Results:: The applicability of RDF based descriptor for the correlation with pKi and EC50 values is demonstrated, while simple models containing only two or three parameters are able to explain 78 and 86 % of the variance, respectively. The models with explicitly included hydrogens are of comparable quality with the previous models without hydrogens. The analysis of the atom’s dominant contributions highlighted the importance of the hydroxyl groups of the inhibitor near the Asp25 and Asp25’ residues when it is bounded to the protease. Conclusion:: Models based on the RDF weighted by the number of valence shell electrons for correlating small number of molecular descriptors and physicocehmical properties for structures with and without hydrogens are of comparable quality and both can be used for identification of relevant functional groups and interactions. Other:: Our approach can be integrated to the next generation virtual screening methods, because is fast, reliable with high predictability potential.

In the recent past, chitosan demonstrated intriguing applications in the different domains of biomedical science, probably due to its biodegradability, biocompatibility, minimal toxicity, cost-effectiveness, and easy-going synthetic procedures. Chitosan is the second most prevalent amino polysaccharide after cellulose, generated from a deacetylated version of chitin. This short review briefly explains the preparation methods for chitosan from chitin and its role as a drug carrier for biomedical applications.

Plasmepsin V (Plm V) is an essential aspartic protease required for survival of the malaria parasite, Plasmodium falciparum (Pf). Plm V is required for cleaving the PEXEL motifs of many Pf proteins...

Even though the first docking procedures were developed almost 40 years ago, they are still under intense development, alongside with their validation. In this article, we are proposing the use of the quantum free-orbital AlteQ method in evaluating the correctness of ligand binding poses and their ranking. The AlteQ method calculates the electron density in the interspace between the ligand and the receptor, and since their interactions follow the maximum complementarity principle, an equation can be obtained, which describes these interactions. In this way, the AlteQ method evaluates the quality of contacts between the ligand and the receptor, bypasses the drawbacks of using ligand RMSD as a measure of docking quality, and can be considered as an improvement of the “fraction of recovered ligand−receptor contacts” method. Free Windows and Linux versions of the AlteQ program for assessing complementarity between the ligand and the receptor are available for download at www.chemosophia.com.

Background: The SARS-CoV-2 3CLpro is one of the primary targets for designing new and repurposing known drugs. Methodology: A virtual screening of molecules from the Natural Product Atlas was performed, followed by molecular dynamics simulations of the most potent inhibitor bound to two conformations of the protease and into two binding sites. Conclusion: Eight molecules with appropriate ADMET properties are suggested as potential inhibitors. The greatest benefit of this study is the demonstration that these ligands can bind in the catalytic site but also to the groove between domains II and III, where they interact with a series of residues which have an important role in the dimerization and the maturation process of the enzyme., Graphical abstract

Curcumin (diferuloylmethane) is bioactive phenolic compound which exerts diverse antimetastatic effect. Several studies have reported the antimetastatic effect of curcumin by its ability to modulate the epithelial-to-mesenchymal transition (EMT) process in different cancers, but underlying molecular mechanism is poorly understood. EMT is a highly conserved biological process in which epithelial cells acquire mesenchymal-like characteristics by losing their cell-cell junctions and polarity. As a consequence, deviation in cellular mechanism leads to cancer metastasis and thereby death. In this perspective, we explored the antimetastatic potential and mechanism of curcumin on the EMT process by establishing in vitro EMT model in lungs cancer (A549) cells induced by TGF-β1. Our results showed that curcumin mitigates EMT by regulating the expression of crucial mesenchymal markers such as MMP2, vimentin and N-cadherin. Besides, the transcriptional analysis revealed that the curcumin treatment differentially regulated the expression of 75 genes in NanoString nCounter platform. Further protein-protein interaction network and clusters analysis of differentially expressed genes revealed their involvement in essential biological processes that plays a key role during EMT transition. Altogether, the study provides a comprehensive overview of the antimetastatic potential of curcumin in TGF-β1-induced EMT in lung cancer cells.The online version contains supplementary material available at 10.1007/s13205-022-03360-7.

Background: A principle of complementarity is a well-established concept in chemistry and biology. This concept is based on the overlap of electron clouds of the molecules in question. Materials & methods: In this article, one such approach (an in-house developed quantum free-orbital AlteQ method) was used to evaluate the complementarity of 51 CDK–ligand complexes. Results: A significant universally applicable correlation (adjusted R2 = 0.9749; p < 2.2 × 10-16) relating the product of ligand and enzyme electron densities to the product of distances between the contacting atomic centers and the type of atoms involved in the interaction was found. Conclusion: The terms calculated in this article can provide a good basis for prognosis of bioactivity and scientifically based molecular docking.

Nucleophilic ring opening reactions of epoxides with aromatic amines are in the forefront of the synthetic organic chemistry research to build new bioactive scaffolds. Here, convenient, green, and highly efficient regioselective ring opening reactions of sterically hindered (2R,3S)-3-(N-Boc-amino)-1-oxirane-4-phenylbutane with various poorly reactive aromatic amines are accomplished under microwave irradiation in nitromethane. All the reactions effectively implemented for various aromatic amines involve the reuse of nitromethane that supports its dual role as a solvent and catalyst. The corresponding new β-alcohol analogs of hydroxyethylamine (HEA) are isolated in 41–98% yields. The reactions proceed under mild conditions for a broad range of less reactive and sterically hindered aromatic amines. Proton NMR experiments suggest that the nucleophilicity of amines is influenced by nitromethane, which is substantiated by the extensive computational studies. Overall, this methodology elucidates the first-time use of nitromethane as a solvent for the ring opening reactions under microwave conditions involving an equimolar ratio of epoxide and aromatic amine without any catalyst, facile ring opening of complex epoxide by less reactive aromatic amines, low reaction time, less energy consumption, recycling of the solvent, and simple workup procedures.

The properties of TiO2 can vary greatly, depending on the size and morphology of the particles used. The modeling of TiO2 nanoparticles of various diameters, and the study of their properties and morphology are of great interest for identifying the factors affecting the properties of nanoparticles. In this paper, the theoretical study based on the modeling of nanoparticles of TiO2 and the relationship between morphological parameters and calculated descriptors has been carried out. As a result of simulation, the nanoparticle structures of the composition Ti17O34–Ti568O1136 have been obtained. The surface analysis of nanoparticles has been carried out, and their density is calculated. We explained the increase in N3 dye adsorption and photovoltaic parameters with the decrease in the surface area of nanoparticles. We found that dye adsorption, short circuit photocurrent density, and power conversion efficiency are related to the solvent accessible surface area of the nanoparticle as well as the accessible surface area of oxygens.

Malaria, a global threat to the human population, remains a challenge partly due to the fast-growing drug-resistant strains of Plasmodium species. New therapeutics acting against the pathogenic asexual and sexual stages, including liver-stage malarial infection, have now attained more attention in achieving malaria eradication efforts. In this paper, two previously identified potent antiplasmodial hydroxyethylamine (HEA) compounds were investigated for their activity against the malaria parasite's multiple life stages. The compounds exhibited notable activity against the artemisinin-resistant strain of P. falciparum blood-stage culture with 50% inhibitory concentrations (IC50) in the low micromolar range. The compounds' cytotoxicity on HEK293, HepG2 and Huh-7 cells exhibited selective killing activity with IC50 values > 170 μM. The in vivo efficacy was studied in mice infected with P. berghei NK65, which showed a significant reduction in the blood parasite load. Notably, the compounds were active against liver-stage infection, mainly compound 1 with an IC50 value of 1.89 μM. Mice infected with P. berghei sporozoites treated with compound 1 at 50 mg kg−1 dose had markedly reduced liver stage infection. Moreover, both compounds prevented ookinete maturation and affected the developmental progression of gametocytes. Further, systematic in silico studies suggested both the compounds have a high affinity towards plasmepsin II with favorable pharmacological properties. Overall, the findings demonstrated that HEA and piperidine possessing compounds have immense potential in treating malarial infection by acting as multistage inhibitors.

Despite the fact that there are already drugs for cancer, they still show strong toxicity to the human organism. That is why it is necessary to establish the factors affecting activity in order to develop new, more effective drugs aimed at tumor cells, minimizing harm to healthy cells. The present research is based on electronic properties calculation of the complexes using AlteQ approach. In the focus of this study are complexes of human dihydrofolate reductase (hDHFR) with a series of known inhibitors bound in the active site. Further, a statistical analysis was performed to establish the relationships between a myriad electronic characteristics and IC50. The change in total volume and the change of own electrons number of hydrogen atoms in their atomic basins are identified as the descriptors correlating the most with the hDHFR inhibition potency. Additionally, two lipophilic parts of protein (Thr56, Ser59, Ile60 and Ile7, Val8, Ala9) were found, which act as a key factor in decreasing bioactivity. The depth analysis of intermolecular interactions showed that the interactions between water molecules and ligand play a crucial role in hDHFR inhibition. Furthermore, the molecular dynamics simulations were used for deeper understanding of the structural inhibition, each for 50 ns time scale in explicit water conditions. Thus, the AlteQ approach made it possible to determine the factors influencing the activity and evaluate them not only qualitatively, but also quantitatively.

Background: A great step toward describing the structure of the molecular electron was made in the era of quantum chemical methods. Methods play a very important role in the prediction of molecular properties and in the description of the reactivity of compounds, which cannot be overestimated. There are many works, books, and articles on quantum methods, their applications, and comparisons. At the same time, quantum methods of a high level of theory, which give the most accurate results, are time-consuming, which makes them almost impossible to describe large complex molecular systems, such as macromolecules, enzymes, supramolecular compounds, crystal fragments, and so on. Objective: To propose an approach that allows real-time estimation of electron density in large systems, such as macromolecules, nanosystems, proteins. Methods: AlteQ approach was applied to the tolopogical analysis of electron density for “substrate - cytochrome” complexes. The approach is based on the use of Slater’s type atomic contributions. Parameters of the atomic contributions were found using high resolution X-ray diffraction data for organic and inorganic molecules. Relationships of the parameters with atomic number, ionization potentials and electronegativities were determined. The sufficient quality of the molecular electron structure representation was shown under comparison of AlteQ predicted and observed electron densities. AlteQ algorithm was applied for evaluation of electron structure of “CYP3A4 – substrate” complexes modeled using BiS/MC restricted docking procedure. Topological analysis (similar to Atoms In Molecules (AIM) theory suggested by Richard F.W. Bader) of the AlteQ molecular electron density was carried out for each complex. The determination of (3,-1) bond, (3,+1) ring, (3,+3) cage critical points of electron density in the intermolecular “CYP3A4 – substrate” space was performed. Results: Different characteristics such as electron density, Laplacian eigen values, etc. at the critical points were computed. Relationship of pKM (KM is Michaelis constant) with the maximal value of the second Laplacian eigen value of electron density at the critical points and energy of complex formation computed using MM3 force field was determined. Conclusion: It was shown that significant number of (3,-1) bond critical points are located in the intermolecular space between the enzyme site and groups of substrate atoms eliminating during metabolism processes.

The dormant Mycobacterium tuberculosis is evolved to develop the tolerance against the acidification of phagolysosome by the action of gamma interferon. The molecular mechanism responsible for the development of the resistance towards the acidic conditions in M. tuberculosis is not fully understood. Therefore, the current analysis was performed which studies the mechanism of acid tolerance by correlating the alteration in the protonation state of conserved residues in virulent proteins with changes in their folding states. The pH dependencies of proteins were studied using an efficient computational scheme which enables the understanding of their conformational behavior by molecular dynamics (MD) simulations. The adopted methodology involves cyclically updating of the ionization states of titrable residues in the studied proteins with conventional MD steps, which were applied to the newly generated ionization configuration. Significant pH-dependent protein structural stability parameters consistent with the changes of the protonation states of conserved residues were observed. Among the studied proteins, the peptidoglycan binding protein ompATB, carboxylesterase LipF and two-component systems' transcriptional regulator PhoP showed highest structural conservation in the observed acidic pH range throughout the course of MD simulations. The current study provides a better understanding of acid tolerance mechanisms present in M. tuberculosis and can facilitate the drug development strategies against the dormant protein targets.Communicated by Ramaswamy H. Sarma.

In the current era of a pandemic, infections of COVID-19 and Tuberculosis (TB) enhance the detrimental effects of both diseases in suffering individuals. The resistance mechanisms evolving in

Kyasanur forest disease (KFD) is a tick-borne, neglected tropical disease, caused by KFD virus (KFDV) which belongs to Flavivirus (Flaviviridae family). This emerging viral disease is a major threat to humans. Currently, vaccination is the only controlling method against the KFDV, and its effectiveness is very low. An effective control strategy is required to combat this emerging tropical disease using the existing resources. In this regard, in silico drug repurposing method offers an effective strategy to find suitable antiviral drugs against KFDV proteins. Drug repurposing is an effective strategy to identify new use for approved or investigational drugs that are outside the scope of their initial usage and the repurposed drugs have lower risk and higher safety compared to de novo developed drugs, because their toxicity and safety issues are profoundly investigated during the preclinical trials in human/other models. In the present work, we evaluated the effectiveness of the FDA approved and natural compounds against KFDV proteins using in silico molecular docking and molecular simulations. At present, no experimentally solved 3D structures for the KFD viral proteins are available in Protein Data Bank and hence their homology model was developed and used for the analysis. The present analysis successfully developed the reliable homology model of NS3 of KFDV, in terms of geometry and energy contour. Further, in silico molecular docking and molecular dynamics simulations successfully presented four FDA approved drugs and one natural compound against the NS3 homology model of KFDV.

Exploring potent herbal medicine candidates is a promising strategy for combating a pandemic in the present global health crisis. In Ayurveda (a traditional medicine system in India)

Novel coronavirus disease 2019 (COVID-19) has significantly altered the socio-economic status of countries. Although vaccines are now available against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a causative agent for COVID-19, it continues to transmit and newer variants of concern have been consistently emerging world-wide. Computational strategies involving drug repurposing offer a viable opportunity to choose a medication from a rundown of affirmed drugs against distinct diseases including COVID-19. While pandemics impede the healthcare systems, drug repurposing or repositioning represents a hopeful approach in which existing drugs can be remodeled and employed to treat newer diseases. In this review, we summarize the diverse computational approaches attempted for developing drugs through drug repurposing or repositioning against COVID-19 and discuss their advantages and limitations. To this end, we have outlined studies that utilized computational techniques such as molecular docking, molecular dynamic simulation, disease-disease association, drug-drug interaction, integrated biological network, artificial intelligence, machine learning and network medicine to accelerate creation of smart and safe drugs against COVID-19.

A novel series of a hybrid class of hybrid thiazolidin-4-one derivatives were designed and synthesized through one-pot catalytic synthesis. The reaction was catalyzed in the presence of silica-H2SO4(+6). The derivatives computational ADMET profile was calculated. The study shows that most active derivatives have optimal logP, higher anti-inflammatory activity score, and poor metabolism at the sight of P450-3A4 and 2D6. The entire series of derivatives were further evaluated for anti-tubercular (against Mycobacterium tuberculosis H37Rv (Resistant strain)) and anti-inflammatory activity (in-vivo assay using Wistar rat). The result showed that derivatives 4c, 4h, and 4m have significant potency against tested M. tuberculosis. However, derivatives 4i and 4j found significantly active against inflammation. In vitro COX inhibition assay also supported the result in favor of selectivity and efficacy of derivatives.

Electronic properties of benzothiadiazole (BTD) unit containing dyes adsorbed on TiO2 nano-particles have been estimated using Quantum Theory of Atoms in Molecules (QTAIM). We found that short circuit photocurrent density Jsc and open circuit photovoltage Voc of the studied DSSCs are well related to the electronic properties of dyes, namely charges of BTD atomic basins of nitrogens, summary isodensity surface area and summary volume of hydrogen basins. Analysis of deviations of predicted and observed photovoltaic properties allowed to reveal device fabrication details influencing positively and negatively on device efficiency. Found relationships have been used for design of new promising dyes and recommendation of the better fabrication details of DSSCs with significantly higher photovoltaic properties as compared to the studied and published. For newly designed metal-free BTD-unit containing dyes, Jsc is expected to reach 20.7–25.8 mA/cm2, Voc – 0.858–1.029 V and power conversion efficiency η – 10.6–16.3%.

The highly efficient oxygen mediated reduction of functional chromones with sodium borohydride (NaBH4) catalyzed by cobalt(II) porphyrins afforded biologically active chroman-4-ols as the reduction products in 80–98% yields. Oxygen assists in the formation of hydridocobalt(III) porphyrin as a key intermediate, which releases hydride rapidly to reduce the chromones. Additionally, the correlation between quantum calculation results of the catalysts’ conversions, yields, times and logarithms of the rate constants for the oxygen assisted reduction reaction was studied. The mechanism of the reaction was also justified by establishing a quantitative relationship between the rate constant, the α-HOMO orbital of the catalytic complex and the stabilization energy of the complex with oxygen.