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The heats of formation of thirty-five molecules containing antimony atoms have been calculated using G4(MP2)-XK, B3LYP, M06, M06-HF, M06-2X, BMK, wB97XD, and TPSSh atomization. The discrepancies between the predicted and the reported heats of formation vary in the range of 0.0-83 kcal mol

The structure and substitution energies of dichlorotris(triphenylphosphine)ruthenium(II) complex, [RuCl2(PPh3)3], was computed with ten different methods at the density functional theory level usin...

The disease outbreak caused by SARS-CoV-2 continues to rise worldwide, even in countries which have considered it controlled. As new cases appear daily, infecting millions of people and causing thousands of deaths, the current in silico study aims to investigate the imidazolic alkaloids of the species Pilocarpus microphyllus (Jaborandi) as a potential inhibitory activity against the Mpro protease from SARS-CoV-2, since it plays a fundamental role in the processing of polyproteins that are translated from viral RNA. Jaborandi is distributed in some Brazilian biomes, being easily identified, yet little researched, with proven anti-inflammatory, contraceptive, anti-diabetic and gastroprotective activities. In this work, DFT calculation of thermodynamic properties, electrostatic potential surface, frontier molecular orbitals and descriptors of chemical reactivity of imidazolic alkaloids were associated with the use of molecular docking techniques, molecular dynamics and ADMET predictions. One can verify a good reactivity chemistry and energetic stability of epiisopiloturine, epiisopilosine, isopilosine and e pilosine with some residues of amino acids present in the active site of the main protease of COVID-19. In this sense, the results point out to the imidazolic alkaloids of Jaborandi as promising targets for in vitro and in vivo tests, as possible candidates for inhibitors of the enzyme Mpro.

Statistics show alarming numbers of infected and killed in the world, caused by the Covid-19 pandemic, which still doesn't have a specific treatment and effective in combating all efforts to seek treatments and medications against this disease. Natural products are of relevant interest in the search for new drugs. Thus, Buriti oil (Mauritia flexuosa L.) is a natural product extracted from the fruit of the palm and is quite common in the legal Amazon region, Brazil. In the present work, the anti-Covid-19 biological activity of some constituents of Buriti oil was investigated using in silico methods of Molecular Docking and Molecular Dynamics Simulations. The main results of Molecular Docking revealed favorable interaction energies in the formation of the 2GTB peptidase complex (main peptidase of SARS-CoV) with the 13-cis-s-carotene ligands (ΔGbind = -10.23Kcal mol-1), 9-cis -s-carotene (ΔGbind = -9.82Kcal mol-1), and α-carotene (ΔGbind = -8.34Kcal mol-1). Molecular Dynamics simulations demonstrated considerable interaction for these ligands with emphasis on α-carotene. Such theoretical results encourage and enable a direction for experimental studies in vitro and in vivo, essential in the development of new drugs with enzymatic inhibitory action for Covid-19.Communicated by Ramaswamy H. Sarma.

A Leishmaniose é uma doença infecciosa que ocasiona a morte de 26.000 a 65.000 pessoas anualmente, estima-se que no ano de 2019 houve 700.000 a 1 milhão de novos casos. Estes dados são preocupantes e está relacionado à falta de saneamento básico que favorece a proliferação dos vetores, além da ausência de medicamentos eficientes com mecanismos de ação alternativos e com menos efeitos colaterais. Em meio a essa necessidade de novos agentes inibitórios, este estudo teve como objetivo realizar uma predição computacional de alvos moleculares de Leishmania para um complexo metálico de rutênio com epiisopiloturina e óxido nítrico (Epiruno2). O processo de docking molecular foi realizado empregando-se o software Autodock Tools (ADT) versão 1.5.6. As proteínas alvos foram consideradas rígidas, enquanto que o Epiruno2 foi considerado flexível. A glicoproteína GP63 (1lml) representa mais de 1% da proteína total do parasito tendo em vista que a 1lml é uma metaloprotease que predomina grupos funcionais em seu sítio ativo, torna-se um alvo atrativo em estudos de atividade inibitória. O docking molecular entre o Epiruno2 e a 1lml resultou na melhor conformação de encaixe deste estudo, com energia de Gbind a de -8,05 Kcal.mol-1 e uma constante de inibição de 1,26 µM. Também foi observada a formação de quatro pontes de hidrogênio, demonstrando ser um forte candidato a fármaco antileishmania. Concluindo-se que o composto Epiruno2 é clinicamente atrativo para estudos experimentais futuros ex vivo, in vitro e in vivo, pois seus resultados in sílico apresentaram boas interações moleculares para todas as proteínas alvo deste estudo. Leishmaniasis is an infectious disease that causes the death of 26,000 to 65,000 people annually, it is estimated that in 2019 there were 700,000 to 1 million new cases. These data are worrying and are related to the lack of basic sanitation that favors the proliferation of vectors, in addition to the absence of efficient drugs with alternative mechanisms of action and with less side effects. Amid this need for new inhibitory agents, this study aimed to perform a computational prediction of Leishmania molecular targets for a ruthenium metal complex with epiisopiloturine and nitric oxide (Epiruno2). The molecular docking process was performed using the Autodock Tools (ADT) software version 1.5.6. The target proteins were considered rigid, while Epiruno2 was considered flexible. The glycoprotein GP63 (1lml) represents more than 1% of the total protein of the parasite, considering that 1lml is a metalloprotease that predominates functional groups in its active site, it becomes an attractive target in studies of inhibitory activity. The molecular docking between Epiruno2 and 1lml resulted in the best fit conformation in this study, with Gbinda energy of -8.05 Kcal.mol-1 and an inhibition constant of 1.26 µM. The formation of four hydrogen bonds was also observed, demonstrating to be a strong candidate for antileishmania drug. In conclusion, the compound Epiruno2 is clinically attractive for future experimental studies ex vivo, in vitro and in vivo, as in silico results showed good molecular interactions for all the target proteins in this study.

Leishmaniasis is an infectious disease that affects both animals and humans, caused by flagellated parasites belonging to the genus Leishmania. The disease is estimated to reach about 700,000 to 1 million people, causing the deaths of 20 to 30,000 individuals annually. Thus, the present study aims to perform molecular docking tests and evaluation of antileishmania activity in vitro of a ruthenium complex with epiisopiloturine and nitric oxide. AutoDockTools-1.5.6 software was used to perform molecular docking tests. Molecular targets were considered rigid, and Epiruno2 considered flexible. The genetic algorithm Lamarckian (AGL) with global search and pseudo-Solis and Wets with local search were the methods adopted in the docking. The most promising results of molecular interaction were achieved in the targets Pteridine reductase and UDP-glucose Pyrophosphorylase with rates of -10.68 Kcal·mol-1 and -10.51 Kcal·mol-1, respectively. This demonstrates that Epiruno2 has molecular affinity with the targets of L. major. In vitro assays prove the antileishmania activity of the complex in the face of promastigote forms with inhibition of growth, concluding through this study that the Epiruno2 complex has antileishmania activity.

O processo educacional vem passando por grandes transformacoes nas ultimas decadas, como por exemplo, atraves da utilizacao de ferramentas que proporcionam a visualizacao e a reproducao de modelos dinâmicos. Neste sentido, os softwares de simulacao e as ferramentas de modelagem molecular surgem com a finalidade de desenvolverem a compreensao conceitual e minimizarem o aprendizado mecânico dos estudantes no Ensino de Quimica (EQ). A presente pesquisa busca promover uma melhor compreensao de conceitos e calculos sobre os conteudos de Termodinâmica Quimica (TQ), abordados na disciplina de Fisico-Quimica I (FQI) de estudantes do curso de Licenciatura em Quimica da Universidade Estadual do Piaui (UESPI). Nesse sentido, foram produzidos e aplicados tutoriais, a fim de facilitar a utilizacao dos softwares de modelagem molecular pelos graduandos, a partir de aulas praticas computacionais. O metodo de pesquisa empregado e uma abordagem qualitativa do tipo estudo de caso, com a aplicacao de questionarios subjetivos e escalas do tipo Likert de cinco pontos, como instrumentos de coleta de dados. A partir dos resultados pode-se perceber que as utilizacoes dessas ferramentas no ensino contribuem para o aprofundamento do conhecimento termodinâmico, ajudam a estabelecer uma visao mais realistica e simbolica do mundo microscopico, minimizam as limitacoes matematicas na obtencao dos calculos e melhoram o interesse e a motivacao dos estudantes pelo aprendizado.

HLA epitope analysis emerged as a strategy to determine alloimmune risk in solid organ transplantation. However, it requires not only knowledge on HLA amino acids sequences, but also on HLA three-dimensional structures. Unfortunately, the number of structures available is still unsatisfactory. This work reports the modelling of 106 heterotrimeric (alpha chain + β2M + peptide) HLA class I molecules. The models were generated by homology modelling using Modeller, refined using GalaxyRefine server, heterodimerized with Swiss-PDB Viewer and, finally, assessed as to their structural quality through Dali server. The final structures were made available through a free online database, pHLA3D ( www.phla3d.com.br ), developed in Ruby language using the Ruby on Rails web framework. Structural parameters were similar between refined molecules and their templates. The new database may improve HLA epitope analysis and better guide risk assessment in solid organ transplantation setting.

Computational chemistry only gained international recognition after making a significant contribution to the scientific advances that resulted in Nobel prizes. With the technological evolution of the last decades, software was created with the aim of studying, investigating and understanding chemical processes at the molecular level of experimental studies. This promoted research agility and reduced costs with laboratory work. In this work, 5 different sets of computational bases were studied: STO-3G, LAN2DZ, SDD, 3-21G and DGDZVP, using the GaussView 5 and Gaussian 09w software with the DFT and B3LYP functional hybrid method. The distance and angle parameters of the di-u-chloro-bis complex [chlorine (4,7-dimethyl-1,10-phenanthroline) cadmium (II)] were obtained. The RMSD values obtained for each of the bases were observed. Molecular docking test was performed for each base, to verify which one had better parameters. It was noted in this study that the set of SDD bases presented the best results in the tests, being classified as the most suitable for studies of structures containing the element cadmium in its composition. La química computacional solo ganó reconocimiento internacional después de hacer una contribución significativa a los avances científicos que resultaron en premios Nobel. Con la evolución tecnológica de las últimas décadas, se creó un software con el objetivo de estudiar, investigar y comprender procesos químicos a nivel molecular de estudios experimentales. Esto promovió la agilidad de la investigación y redujo los costos con el trabajo de laboratorio. En este trabajo se estudiaron 5 conjuntos diferentes de bases computacionales: STO-3G, LAN2DZ, SDD, 3-21G y DGDZVP, utilizando el software GaussView 5 y Gaussian 09w con el método híbrido funcional DFT y B3LYP. Se obtuvieron los parámetros de distancia y ángulo del complejo di-u-cloro-bis [cloro (4,7-dimetil-1,10-fenantrolina) cadmio (II)]. Se observaron los valores de RMSD obtenidos para cada una de las bases. Se realizó prueba de acoplamiento molecular para cada base, para verificar cuál tenía mejores parámetros. En este estudio se observó que el conjunto de bases SDD presentó los mejores resultados en las pruebas, siendo clasificado como el más adecuado para estudios de estructuras que contienen el elemento cadmio en su composición. A química computacional só ganhou reconhecimento internacional depois de contribuir significativamente para os avanços científicos que resultaram em prêmios Nobel. Com a evolução tecnológica das últimas décadas softwares foram criados com o objetivo de estudar, investigar e compreender os processos químicos a nível molecular de estudos experimentais. Isso promoveu agilidade nas pesquisas e reduziu custos com trabalhos laboratoriais. Neste trabalho foram estudados 5 diferentes conjuntos de bases computacionais: STO-3G, LAN2DZ, SDD, 3-21G e DGDZVP, utilizando o software GaussView 5 e Gaussian 09w com o método DFT e B3LYP híbrido funcional. Foram obtidos os parâmetros de distância e ângulo do complexo di-u-cloro-bis [cloro (4,7-dimetil-1,10-fenantrolina) cádmio (II)]. Observou-se os valores de RMSD obtidos para cada uma das bases. Teste de docking molecular foi realizado para cada base, para verificar qual apresentava melhores parâmetros. Notou-se neste estudo que o conjunto de bases SDD apresentou os melhores resultados nos testes, sendo classificado como o mais adequado para estudos de estruturas contendo o elemento cádmio em sua composição.

We performed a biological evaluation of antileishmanial activity, in silico ADME-Tox profile, and molecular docking of riparins A-F. The antileishmanial activity was evaluated in Leishmania major promastigotes, whereas the cytotoxic activity was tested on murine macrophages. Computational parameters were predicted by in silico analysis. Molecular docking was performed with 18 L. major molecular targets. Riparins, especially RipC and RipE, showed cytotoxic activity in vitro toward L. major promastigotes and a high selectivity index. Riparins showed small differences in their physicochemical properties, such as polarity and aqueous solubility. LogP was an important parameter for the differences in the antileishmanial activity between the molecules. In molecular docking, the ligands displayed Ki 1 μM for LmNMT and LmLEI. Significant molecular interactions were observed with residues from the active site and adjacent regions of such enzymes. Thus, riparins have the potential for application in antileishmanial therapy.

Chagas disease is a neglected tropical disease caused by the protozoan Trypanosoma cruzi. Currently only the drugs benznidazole and nifurtimox are used in the treatment of the disease. However, in addition to adverse effects, these drugs have reduced effectiveness, especially for chronic cases of the disease. A viable alternative is the investigation of new drugs from natural products. Catharanthus roseus is a common plant in tropical regions and has more than 130 terpenoids of relevant scientific interest. The present work aimed to investigate natural products in the prospect of new antichagasics drugs. In silico molecular docking were performed for 21 alkaloids derived from Catharanthus roseus in the active site of cruzain, the main cysteine ​​protease of Trypanosoma cruzi. The main results demonstrated the formation of enzyme complexes of considerable stability for the compounds strictosidine (ΔG = -11.23 Kcal.mol-1), ajmalicine (ΔG = -9.59 Kcal.mol-1) and serpentine (ΔG = - 9.28 Kcal.mol-1). These results demonstrated a good enzyme inhibitory activity of cruzain. ADMET and PASS predictions showed promising results for absorption rates and bioavailability. Therefore, the investigated molecules were considered promising in the prospect of new anti-chagasic drugs. La enfermedad de Chagas es una enfermedad tropical desatendida causada por el protozoario Trypanosoma cruzi. Actualmente, solo los fármacos benznidazol y nifurtimox se utilizan en el tratamiento de la enfermedad, sin embargo, además de los efectos adversos, estos fármacos tienen una eficacia reducida, principalmente para los casos crónicos de la enfermedad. Una alternativa viable es la investigación de nuevos fármacos a partir de productos naturales. Catharanthus roseus es una planta común en las regiones tropicales y tiene más de 130 alcaloides de interés científico relevante. El presente trabajo tuvo como objetivo investigar productos naturales en la prospección de nuevos fármacos antichagásicos. Se realizaron estudios de anclaje molecular in silico para 21 terpenoides derivados de Catharanthus roseus en el sitio activo de cruzina, la principal cisteína proteasa de Trypanosoma cruzi. Los principales resultados demostraron la formación de complejos enzimáticos de considerable estabilidad para los compuestos strictosidina (ΔG = -11,23 Kcal.mol-1), ajmalicina (ΔG = -9,59 Kcal.mol-1) y serpentina (ΔG = -9,28 Kcal.mol-1). Tales resultados demostraron una buena actividad inhibitoria enzimática de cruzain. Las predicciones a través de ADMET y PASS mostraron resultados prometedores para las tasas de absorción y la biodisponibilidad. Por lo tanto, las moléculas investigadas se consideraron prometedoras en la prospección de nuevos fármacos antichagásicos. A Doença de Chagas é uma doença tropical negligenciada causada pelo protozoário Trypanosoma cruzi. Atualmente apenas os fármacos benznidazol e nifurtimox são utilizados no tratamento da doença, porém, além dos efeitos adversos, estes fármacos possuem eficácia reduzida principalmente para casos crônicos da doença. Uma alternativa viável consiste na investigação de novos fármacos a partir de produtos naturais. A Catharanthus roseus é uma planta comum em regiões tropicais e possui mais de 130 alcaloides de relevante interesse científico. O presente trabalho teve por objetivo investigar produtos naturais na prospecção de novos fármacos antichagásicos. Estudos in silico de ancoragem molecular foram realizados para 21 terpenoides derivados da Catharanthus roseus no sítio ativo da cruzaína, principal cisteíno protease do Trypanosoma cruzi. Os principais resultados demonstraram a formação de complexos enzimáticos de considerável estabilidade para os compostos estrictosidina (ΔG = -11,23 Kcal.mol-1), ajmalicina (ΔG = -9,59 Kcal.mol-1) e serpentina (ΔG = -9,28 Kcal.mol-1). Tais resultados demonstraram uma boa atividade inibidora enzimática da cruzaína. Previsões via ADMET e PASS apresentaram resultados promissores para taxas de absorção e biodisponibilidade. Assim sendo, as moléculas investigadas foram consideradas como promissoras na prospecção de novos fármacos antichagásicos.

In this work, we introduce a technique to choose polarization functions directly from the primitive set of Gaussian exponent without the necessity to optimize or even reoptimized them. For this purpose, initially, we employed Gaussian basis sets generated by using the Polynomial Generator Coordinate Hartree-Fock (PGCHF) method, and later we extended our technique to the cc-pVQZ and pc-3 Gaussian basis sets in order to show how our technique works and how good it is. Using the new polarized basis sets, from our technique, total electronic energies, equilibrium geometries, and vibrational frequencies were calculated for a set of molecules containing atoms from H(Z = 1) to Ba(Z = 56). The technique presented here can be used with any Gaussian basis set flexible (large) enough and also can be used to choose Gaussian basis set exponents from one basis set to another as polarization functions.

To improve the availability of three-dimensional (3D) structures of HLA molecules, we created the pHLA3D database. In its first version, we modeled and published 106 3D structures of HLA class I molecules from the HLA-A, HLA-B, and HLA-C loci. This paper presents an update of this database, providing more 127 3D structures of HLA class II molecules (41 DR, 42 DQ, and 44 DP), predicted via homology modeling with MODELLER and SWISS-MODEL. These new 3D structures of HLA class II molecules are now freely available at pHLA3D (www.phla3d.com.br) for immunologists and other researchers working with HLA molecules.

In this paper, we have applied state-of-the-art technologies and new investigations were developed focusing on obtaining simple and inexpensive molecules for treating cardiovascular diseases, as they are considered the leading cause of death in the world. For the first time, the inclusion complex of sulcatone (SU) and β-cyclodextrin (β-CD) was achieved (using a spray drier) and characterized making use of spectroscopic, thermal and computational methods. In addition, the system was evaluated regarding its vasorelaxant properties. Evidence of the inclusion complex formation was provided using different techniques, such as X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR), and 1H nuclear magnetic resonance (NMR) spectroscopies and then deduced by pharmacological experiments, which showed significant changes in relation to the initial material.

We have prepared, by a sol-immobilization method, bimetallic catalysts with different Au:Pt atomic ratios supported on commercial SrCO3. The catalytic performance for the oxidation reaction of benzyl alcohol of such materials was compared to the monometallic counterparts, aiming at the obtaining of the best composition of the material. It was found that the Au:Pt atomic ratio presents a remarkable effect on the system performance, i.e., Pt-rich systems are more selective; however, less active. Thus, an equilibrium related to the activity and selectivity of the system was obtained by considering the yield of the system. Also, some density functional theory (DFT) insights were obtained by using a cluster of 14 atoms of Au and 1 or 2 atoms of Pt. X-ray photoelectron spectroscopy, elemental mapping in scanning transmission electron microscopy before and after catalyst usage, flame atomic absorption spectroscopy, Rietveld refinement, among other techniques, were used and associated to the experimental data, which allowed us to propose a catalytic mechanism for the system, which was important since SrCO3 has not been considered before as catalyst support for alcohol oxidation reactions.

This study performed a physicochemical characterization of the inclusion complex generated between Riparin A and β-cyclodextrin (Rip A/β-CD) and compared the cytotoxic potential of the incorporated Rip A upon Artemia salina larvae. Samples were analyzed by phase solubility diagram, dissolution profile, differential scanning calorimetry, X-ray diffraction, infrared spectroscopy, proton nuclear magnetic resonance, scanning electron microscopy and artemicidal action. Riparin A/β-cyclodextrin complexes presented increased water solubility, AL type solubility diagram and Kst constant of 373 L/mol. Thermal analysis demonstrated reduction of the melt peak of complexed Rip A at 116.2 °C. Infrared spectroscopy confirmed generation of inclusion complexes, 1H NMR pointed out the interaction with H-3 of β-CD cavities, alterations in the crystalline natures of Rip A when incorporated within β-CD were observed and inclusion complexes presented higher cytotoxic on A. salina nauplii, with CL50 value of 117.2 (84.9–161.8) μg/mL. So, Rip A was incorporated into β-CDs with high efficiency and water solubility of Rip A was improved. Such solubility was corroborated by cytotoxic evaluation and these outcomes support the improvement of biological properties for complexes between Riparin A/β-cyclodextrin.

Diarrhea is a condition in which the individual has about three or more daily bowel movements, followed by changes in stool consistency. It is currently considered as one of the worst public health problems due to the number of cases and deaths involved and difficulty of treatment. Thus, the use of natural products is an alternative for new treatments. Among these possibilities is Farnesol (C15H26O), a sesquiterpene found in different herbal species that has known biological activities. The objective of this study was to evaluate the antidiarrheal activity of Farnesol (FOH). Initially, FOH activity was evaluated in models of diarrhea and enteropooling induced by castor oil and PGE2. To evaluate motility, the opioid and cholinergic pathways were studied. In addition, the effect of FOH was investigated in the secretion model in intestinal loops treated with cholera toxin. FOH was evaluated for the ability to absorb fluids in intestinal loops and interact with GM1 receptors using the ELISA method and molecular docking. The dose of 50 mg/kg of FOH showed the best results in all antidiarrheal activity tests with castor oil and PGE2, being considered as the standard dose, reducing motility by anticholinergic mechanisms. There was a reduction in fluid secretion when FOH interacted directly with GM1 receptors; cholera toxin and molecular docking showed strong interaction between farnesol and these targets. In view of the results presented, the antidiarrheal activity occurs through anticholinergic, anti-inflammatory and anti-secretory action, making farnesol a potential candidate for the development of a new drug to treat diarrheal diseases.

COVID-2019 disease, caused by the 2019-nCOV virus or SARS-Cov-2, adds up to just over 290 thousand cases and 12 thousand deaths worldwide. No clinical studies are indicating effective treatments, and the identification of suitable antiviral agents is a crucial step in combating the pandemic. This research constitutes a survey of SARS-Cov-2 proteins from the Protein Data Bank (PDB), eligible as targets for docking of inhibitory substances. later, in silico tests were performed with two enzymatic targets in interaction with the drugs Ledipasvir and Ombitasvir. Prospecting in the PDB reported 29 proteins. 6vsb and 6m17 were selected for docking with Ledispasvir, resulting in interaction energies equal to -6.88 and -6.25kJ / mol, respectively. For the same targets, the drug Ombitasvir obtained -5.96 and -4.53kJ / mol. The study showed the advances in COVID-19 research, presenting 29 structures. The drugs tested showed favorable parameters for continuing in vitro and clinical studies. O vírus COVID-2019, 2019-nCOV ou SARS-Cov-2 soma pouco mais de 290 mil casos e 12 mil mortes pelo mundo. Não existem estudos clínicos indicando tratamentos eficazes, e a identificação de agentes antivirais adequados constitui-se um passo crucial no combate à pandemia. O presente trabalho constitui o levantamento de proteínas do SARS-Cov-2 a partir do Protein Data Bank (PDB), elegíveis como alvos para docagem de substâncias inibitórias. Posteriormente, foram realizados testes in sílico, com dois alvos enzimáticos em interação com os fármacos Ledipasvir e Ombitasvir. A prospecção no PDB reportou 29 proteínas. Selecionou-se 6vsb e 6m17 para docagem com Ledispasvir, resultando energias de interação iguais a -6.88 e -6.25kJ/mol, respectivamente. Para os mesmos alvos, o fármaco Ombitasvir obteve -5,96 e -4,53kJ/mol. O estudo evidenciou o avanço nas pesquisas relacionadas ao COVID-19, apresentando 29 estruturas enzimáticas. Os fármacos Ledipasvir e Ombitasvir apresentaram parâmetros favoráveis para a continuação de estudos in vitro e clínicos.

Ruthenium complexes are being considered as novel chemotherapeutic alternatives for cancer treatment. In our study, we assessed the antitumoral activities of novel ruthenium complexes coupled to the amino acids proline (RuPro) and threonine (RuThr) in prostate tumor cell lines (DU145) and breast (MCF7), and normal cell lines of the lung fibroblast (GM07492A). Our results revealed that the EC50 of the complexes for DU145 and MCF7 was two times lower than that GM07492A. Moreover, RuPro and RuThr were not able to induce significant genomic instability, cell cycle arrest or cell death in GM07492A, but could induce DNA damage, arrest in G2/M and apoptosis in DU145 and MCF7. Furthermore, BAX, TP53 and ATM were found to be upregulated in DU145 and MCF7 treated with RuPro and RuThr, in which, a higher ASCT2 gene expression was also observed. Using molecular docking, RuPro and RuThr interact with ASCT2, suggesting that this transporter might have a pivotal role in the execution of their activities. Hence, our results with RuPro and RuThr are capable of selectively inducing genetic damage, cell cycle arrest and apoptosis in DU145 and MCF7. We suggest that the selective action of the RuPro and RuThr complexes is related to the higher expression of ASCT2 in the tumor cells.

We have reported Riparin A as a promising antiparasitic molecule ​​against Leishmania amazonensis promastigotes. This work evaluated the acute oral toxicity of Riparin A and its anxiolytic effects using in vivo models and computational tools. Mice were submitted to acute oral toxicity tests (Guideline OECD 423). Later, anxiety assays with Riparin A (50, 100 and 200 mg/kg: elevated plus maze, light/dark box and marble burying) were performed. Theoretical calculations analyzed interaction of Riparin A with gamma-amino butyric acid (GABA) receptors. Only Riparin A at 2000 mg/kg alter body weight, food and water consumption and urine production after 7 and/or 14 days treatment and increased serum triglycerides. There was increase in the time spent in the open arms (TSOA) and number of transitions between compartments (NTC) and decrease in number of hidden balls (NHB) in Riparin A-treated animals at 200 mg/kg (P 0.05), whose approximate ED

The vasoactive proline-rich oligopeptide termed BPP-BrachyNH2 (H-WPPPKVSP-NH2) induces in vitro inhibitory activity of angiotensin I-converting enzyme (ACE) in rat blood serum. In the present study, the removal of N-terminal tryptophan or C-terminal proline from BPP-BrachyNH2 was investigated in order to predict which structural components are important or required for interaction with ACE. Furthermore, the toxicological profile was assessed by in silico prediction and in vitro MTT assay. Two BPP-BrachyNH2 analogues (des-Trp(1)-BPP-BrachyNH2 and des-Pro(8)-BPP-BrachyNH2) were synthesized, and in vitro and in silico ACE inhibitory activity and toxicological profile were assessed. The des-Trp(1)-BPP-BrachyNH2 and des-Pro(8)-BPP-BrachyNH2 were respectively 3.2- and 29.5-fold less active than the BPP-BrachyNH2-induced ACE inhibitory activity. Molecular Dynamic and Molecular Mechanics Poisson-Boltzmann Surface Area simulations (MM-PBSA) demonstrated that the ACE/BBP-BrachyNH2 complex showed lower binding and van der Wall energies than the ACE/des-Pro(8)-BPP-BrachyNH2 complex, therefore having better stability. The removal of the N-terminal tryptophan increased the in silico predicted toxicological effects and cytotoxicity when compared with BPP-BrachyNH2 or des-Pro(8)-BPP-BrachyNH2. Otherwise, des-Pro(8)-BPP-BrachyNH2 was 190-fold less cytotoxic than BPP-BrachyNH2. Thus, the removal of C-terminal proline residue was able to markedly decrease both the BPP-BrachyNH2-induced ACE inhibitory and cytotoxic effects assessed by in vitro and in silico approaches. In conclusion, the aminoacid sequence of BPP-BrachyNH2 is essential for its ACE inhibitory activity and associated with an acceptable toxicological profile. The perspective of the interactions of BPP-BrachyNH2 with ACE found in the present study can be used for development of drugs with differential therapeutic profile than current ACE inhibitors.

Transgenic maize produced by the insertion of the Cry transgene into its genome became the second most cultivated crop worldwide. Cry gene from Bacillus thuringiensis kurstaki expresses protein derivatives of crystalline endotoxins which confer insect resistance onto the maize crop. Mandatory labeling of processed food containing or made by genetically modified organisms is in force in many countries, so, it is very urgent to develop fast and practical methods for GMO identification, for example, biosensors. In the absence of an available empirical structure of Cry1A(b)16 protein, a theoretical model was effectively generated, in this work, by homology modeling and molecular dynamics simulations based on two available homologous protein structures. Molecular dynamics simulations were carried out to refine the selected model, and an analysis of its global structure was performed. The refined models of Cry1A(b)16 showed a standard fold and structural characteristics similar to those seen in Bacillus thuringiensis Cry1A(a) insecticidal toxin and Bacillus thuringiensis serovar kurstaki Cry1A(c) toxin. After in silico analysis of Cry1A(b)16, two immunoreactive candidate peptides were selected and specific polyclonal antibodies were produced resulting in antibody–peptide interaction. Biosensing devices are expected to be developed for detection of the Cry1A(b) protein as a marker of transgenic maize in food. Proteins 2017; 85:1248–1257. Fil: Plácido, Alexandra. Instituto Politécnico do Porto; Portugal Fil: Coelho, Andreia. Instituto Politécnico do Porto; Portugal Fil: Nascimento, Lucas Abreu. Universidade Federal do Piauí; Brasil Fil: Vasconcelos, Andreanne Gomes. Universidade Federal do Piauí; Brasil Fil: Barroso, María Fátima. Instituto Politécnico do Porto; Portugal Fil: Ramos Jesús, Joilson. Universidade Federal do Piauí; Brasil Fil: Costa, Vladimir. Instituto de Doenças Tropicais Natan Portela; Brasil Fil: Lima, Francisco das Chagas Alves. Universidade Estadual do Piauí; Brasil Fil: Delerue Matos, Cristina. Instituto Politécnico do Porto; Portugal Fil: Ramos, Ricardo Martins. Universidade Estadual do Piauí; Brasil. Instituto Federal do Piauí; Brasil Fil: Marani, Mariela Mirta. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico para el Estudio de los Ecosistemas Continentales; Argentina Fil: Leite, José Roberto de Souza Almeida. Universidade de Brasília; Brasil

The interaction between pyrenetetrasulphonate (PTS) and methyl viologen (MV 2+ ) leads to a 1:1 charge transfer complex (CTC) in the concentration range below mmol L −1 of the ligands. Quantum mechanical calculations show the 1:1 complex having the planar moiety of PTS and the charges of the sulfonate groups stabilized by the twisted rings of the positively charged MV 2+ species. The peculiar nature of PTS includes high fluorescence quantum yield (~1), clear specular UV–vis spectra and fluorescence emission images, as well similar S 2 ←S 0 and S 3 ←S 0 transitions as those of S 1 ←S 0, all of them exhibiting well resolved vibrational structure. MV 2+ has well known electron-accepting properties that favor the complexation. These features were studied as a function of salt concentration and temperature dependences allowing a detailed comprehension of static and dynamic association processes. Quantum mechanical calculations show the 1:1 stabilization of PTS/MV 2+ . In addition the effect of urea on the CTC equilibrium is presented, as expected the additive acts towards the non-complexed species (solvated free ions). The fluorescence quenching of MV 2+ over PTS highlights is one of the applications of this effect for giant vesicles characterization.

In this work, MCM-41 were synthesized hydrothermally and functionalized with calcium and strontium salts by direct method, using the Si/M = 50 molar ratio, in order to elucidate the way as the alkaline earth is incorporated on MCM-41 molecular sieve. The materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, nitrogen adsorption–desorption and theoretical calculations by DFT method. Experimental results and computer simulations showed that the alkaline earths were incorporated on MCM-41 through a complex structure, which negatively influences on basic sites formation.

Schistosomiasis is a neglected tropical disease caused by blood flukes of the genus Schistosoma. This disease control has been widely made by praziquantel-reference drug, but resistance to this drug has already been found. There has been the finding of an imidazole alkaloid in jaborandi leaves-epiisopiloturine, which has known activity against adult, young and egg forms of Schistosoma mansoni. This alkaloid is an apolar molecule with difficult solubility; therefore, the liposomal structure of epiisopiloturine was proposed. Liposomes are carrying structures of drugs that may enhance solubility of compounds such as epiisopiloturine. In this work, we report in vitro epiisopiloturine-loaded liposomes effect formed by different concentrations of lipids 9:1 (weight ratio) dipalmitoylphosphatidylcholine:cholesterol and 8:2 (weight ratio) dipalmitoylphosphatidylcholine:cholesterol. Results have showed that epiisopiloturine extraction and isolation have been successful through high-performance liquid chromatography-HPLC and its purity confirmed through mass spectrometry has showed 287 Da molecular mass. Formulations from 9:1 DPPC:cholesterol and 8:2 DPPC:cholesterol with loaded EPI (300 microg/ml) have killed parasites at 100% after incubation 96 h and 120 h, respectively. Confocal microscopy employed to observe morphological alterations in the tegument of adult form of Schistosoma mansoni. Details from interaction, between epiisopiloturine and liposome, have been achieved by semi-empirical AM1 calculations, which have showed that epiisopiloturine inside is more stable than the outside form, at least 10 kcal. This is first time that schistosomicidal activity has been reported for epiisopiloturine-loaded into liposome.

macrocycles was evaluated by the differencebetween the respective binding energies. The first-row metal binding energy is higher to polyethermacrocycle than to polyamine one. In the case of second-row transition metals, the polyamine lig-and has a higher binding energy than the polyether macrocycle. This behavior is in good agreementwith the macrocyclic cavity dimension, which has a direct relation to the ring size and metal ionsize. While the oxygen–oxygen distances are close to4Ainthepolyether macrocycle cavity, in thepolyamine one the nitrogen–nitrogen distances are close to 5 A.

In this study, the interaction ways between n-butyl amine and SBA-15 molecular sieve were evaluated when the TPD technique is carried out to determine the total acidity of that solid. Experimental results (FTIR, TG/DTG, total acid, and catalytic activity) and theoretical calculations demonstrated that the n-butyl amine, used as probe molecule to total acidity determined by TPD, can act as acid or base depending on the nature and force of the active sites on SBA-15.

The reduction of trans- [Ru(NO)(NH 3 ) 4 (P(OEt) 3 )] 3+ ion was investigated in aqueous medium. Due to the phosphite ligand trans -effect and trans -influence, this complex selectively releases NO or HNO after one or two electrons reduction centered at the nitrosonium ligand (NO + ). These reactions were carried out through electrochemical reduction and using Eu 2+ and zinc amalgam, and the products were identified using electrochemical and spectroscopic techniques. Only the reduction of the nitrosonium ligand to nitric oxide is observed when europium is used as reductant. When the reaction is carried out with Zn(Hg), nitric oxide formation was not observed and N 2 O, an indirect marker of HNO, is detected in solution.

Made available in DSpace on 2018-11-26T17:21:09Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-02-23 Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Fundacao de Amparo a Pesquisa do Estado do Piaui [FAPEPI] Ethnopharmacological relevance: Casearia sylvestris is a medicinal plant traditionally used to treat snakebites, wounds, inflammation and gastric ulcers and scientific supports for have demonstrated its antitumor, antihyperlipidemic and antiparasitic properties. Aim of the study: To assess the effects of a fraction with casearins (FC) on adult mice using classical experimental models of animal behavior and theoretical calculations to verify the interaction of Casearin X (Cas X) with neuron receptors. Materials and methods: Animals divided in 6 groups (n=9/group) were intraperitoneally treated with vehicle (DMSO 4%), FC (2.5, 5, 10 and 25 mg/kg/day) and diazepam (2 mg/kg) for 7 days. Thirty minutes after the last dose of treatment, acute toxicity and behavioral experiments were performed. Results: The highest dose of FC (25 mg/kg/day) caused diarrhea, weight loss and death of one animal. Elevated plus maze test showed that lower doses [2.5 mg/kg/day (36.4 +/- 5.1 s) and 5 mg/kg/day (43.9 +/- 6.2 s)] increased the time spent in open arms (TSOA). Open field test revealed reduction in the number of crossings (54.9%, 51.1%, 48% and 67.7% for 2.5, 5, 10 and 25 mg/kg/day, respectively) in all doses of FC studied and decrease of rearings at 25 mg/kg/day (p < 0.05). Computational calculations showed that the inhibition constant (Ki) for the Cas X -D-1 complex is up to 1000 -fold more favourable than the Cas X-GABA(A) complex. All Delta G degrees values obtained for Cas X -D-1 complexes were more negative than those seen with Cas X-GABA(A) complexes. Conclusions: Findings indicate a probable anxiolytic action of the FC since it reduces the number of crossings and rearings and prolonged the time spent in open arms, without sedative and myorelaxant effects, probably due to the interaction of Cas X with dopaminergic system. Univ Fed Piaui, Postgrad Program Pharmaceut Sci, Teresina, Brazil Univ Fed Piaui, Dept Pharm, Teresina, Brazil Univ Fed Piaui, Postgrad Program Biotechnol RENORBIO, Teresina, Brazil Univ Estadual Piaui, Dept Chem, Quantum Computat Chem Lab, Teresina, Piaui, Brazil State Univ Sao Paulo Julio de Mesquita Filho, Inst Chem, Dept Organ Chem, Araraquara, Brazil Univ Fed Ceara, Fac Med, Dept Physiol & Pharmacol, Fortaleza, Ceara, Brazil Univ Fed Piaui, Expt Cancerol Lab, Dept Physiol & Biophys, Teresina, Brazil State Univ Sao Paulo Julio de Mesquita Filho, Inst Chem, Dept Organ Chem, Araraquara, Brazil CNPq: 484286/2011-0 Fundacao de Amparo a Pesquisa do Estado do Piaui [FAPEPI]: 034/2012-PPP

Aniba riparia (Lauraceae) is an important medicinal plant found in the Amazon region and presents alkaloids of the type alkamide known as riparins. Riparin A is structurally represented as the fundamental core of all Amazon riparins. This work aimed to assess the in vitro antioxidant, antitumor and antileishmanial effects of riparin A. Riparin A presented weak antioxidant capacity by tecniques of DPPH• (EC50 of 296.2 μg mL-1) and ABTS•+ (EC50 of 450.1 μg mL-1), showed moderate activity against colon carcinoma (HCT-116: IC50 of 21.7 μg mL-1) and leishmanicidal activity on promastigotes of L. amazonensis (IC50 of 307.0 ± 79.6, 193.7 ± 44.3 and 81.8 ± 11.2 μg mL-1, respectively, after 24, 48 and 72 h of incubation). Then, in addition to its structural simplicity, riparin A revealed promising biological activities and remarkable in vitro leishmanicidal action, an important result in epidemiological point of view to control leishmaniasis in Brazil, including in the Amazon region. RESUMO Aniba riparia (Lauraceae) é uma importante planta medicinal encontrada na região amazônica que apresenta alcaloides do tipo alcamida e conhecidos como riparinas. Este trabalho teve como objetivo avaliar os efeitos antioxidantes, antitumorais e leishmanicidas in vitro da riparina A. Riparina A apresentou fraca capacidade antioxidante pelas técnicas do DPPH• (CE50 de 296,2 μg mL-1) e ABTS•+ (CE50 de 450,1 μg mL-1), mostrou moderada atividade contra carcinoma de cólon (HCT-116: CI50 de 21,7 μg mL-1) e atividade leishmanicida sobre formas promastigotas de Leishmania amazonensis (CI50 de 307,0 ± 79,6; 193,7 ± 44,3 e 81,8 ± 11,2 μg mL-1, respectivamente, após 24, 48 e 72 h de incubação). Assim, além de sua simplicidade estrutural, a riparina A revelou atividades biológicas promissoras e significativa ação leishmanicida in vitro, resultado importante diante da relevância epidemiológica para controle da leishmaniose no Brasil, inclusive na região amazônica.

Aim: The goal of this study was to increase knowledge about the antimicrobial activity of some synthetic Riparin-derived compounds, alone or in combination with fluoroquinolone antibiotics, against a strain of Staphylococcus aureus resistant to fluoroquinolone by way of overexpression of the NorA efflux pump. Methods and Results: Microdilution tests showed that Riparins A and B did not show any significant antibacterial activity against Staph. aureus strains. On the other hand, the intrinsic antibacterial activity increased with increasing lipophilicity of the compounds, in the following order: Riparin-D (MIC 256 μg ml−1; Log P 2·95) < Riparin-C (MIC 102 μg ml−1; Log P 3·22) < Riparin-E (MIC 16 μg ml−1; Log P 3·57). The addition of all riparins to growth media at subinhibitory concentrations caused an increase in the antibacterial activity of antibiotics against the NorA-overexpressing test strain. Riparin-B, which has two methoxyl groups at the phenethyl moiety, showed the best modulatory effect. Conclusions: Riparin-E is a good anti-staphylococci agent, while Riparin-B functions as a NorA efflux pump inhibitor. Significance and Impact of the Study: Our data suggest the possibility of using Riparin-B in combination with norfloxacin or ciprofloxacin for therapy of infections caused by multi-drug resistant Staph. aureus. Fil: Costa, L. M.. Federal University of Piauí; Brasil Fil: de Macedo, E. V.. Federal University of Piauí; Brasil Fil: Oliveira, F. A. A.. Federal University of Piauí; Brasil Fil: Ferreira, J. H. L.. Federal University of Piauí; Brasil Fil: Gutierrez, S. J. C.. Federal University of Piauí; Brasil Fil: Peláez, Walter José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina Fil: Lima, F. C. A.. Federal University of Piauí; Brasil Fil: Siqueira Jr, J. P.. Federal University of Paraiba; Brasil Fil: Coutinho, H. D. M.. Regional University of Cariri; Brasil Fil: Kaatz, G. W.. Wayne State University School of Medicine; Estados Unidos Fil: de Freitas, R. M.. Federal University of Piauí; Brasil Fil: Barreto, H. M.. Federal University of Piauí; Brasil

Hybrid magnetite materials are interesting for both biomedical and catalytic applications due to their well-known biocompatibility, as well as their magnetic and electric properties. In this work we prepared Fe3O4 nanoparticles (NPs) coated with tannic acid (TA), a natural polyphenol, through two different synthetic routes, aiming to understand the influence of TA in the synthesis step and contribute to the development of water-dispersible magnetic materials. The coating process was verified by information obtained from transmission electron microscopy (TEM), zeta-potential and Fourier transform infrared (FTIR) spectroscopy. The incorporation of TA after Fe3O4 NPs production generated spherical NPs smaller than 10 nm, suggesting that TA plays a fundamental role in the nucleation and organization of Fe3O4 NPs. Data from both density functional theory (DFT) and FTIR allowed us to infer that Fe3O4 interacts mainly with the carbonyl groups of TA. Hybrid materials having improved water-dispersibility are very attractive for biomedical applications., The authors acknowledge the financial support from CNPq (470996/2011-0 and 304684/2011-2 projects), CAPES (nBioNet), FAPEPI, MICINN (Spain) for project MAT 2011-25870, and CENAPAD-UFC by availability of computational resources used in the development of theoretical calculations.

Schistosomiasis affects million people and its control is widely dependent on a single drug, praziquantel. Computational chemistry has led to the development of new tools that predict molecular properties related to pharmacological potential. We conducted a theoretical study of the imizadole alkaloids of Pilocarpus microphyllus (Rutaceae) with schistosomicidal properties. The molecules of epiisopiloturine, epiisopilosine, isopilosine, pilosine, and macaubine were evaluated using theory models (B3lyp/SDD, B3lyp/6-31+G(d,p), B3lyp/6-311++G(d,p)). Absorption, distribution, metabolization, excretion, and toxicity (ADMET) predictions were used to determine the pharmacokinetic and pharmacodynamic properties of the alkaloids. After optimization, the molecules were submitted to molecular docking calculations with the purine nucleoside phosphorylase, thioredoxin glutathione reductase, methylthioadenosine phosphorylase, arginase, uridine phosphorylase, Cathepsin B1 and histone deacetylase 8 enzymes, which are possible targets of Schistosoma mansoni. The results showed that B3lyp/6-311++G(d,p) was the optimal model to describe the properties studied. Thermodynamic analysis showed that epiisopiloturine and epiisopilosine were the most stable isomers; however, the epiisopilosine ligand achieved a superior interaction with the enzymes studied in the molecular docking experiments, which corroborated the results of previous experimental studies on schistosomiasis.

MO calculations were carried out on a cis-[Ru(bpy)2Lx](PF6) 2 complex, where bpy is 2,2'-bipyridine and L is 3-aminopyridine (complex 1 with x = 2), with the Gaussian 03 package using the DFT method. The electronic structure and molecular properties of 1 were characterized in vacuum and in acetonitrile solution, and the results were compared to those obtained from the complex with L = 5,6-bis(3-amidopyridine)-7-oxanorbornene (complex 2 with x = 1). The electronic spectra of 1 and 2 were investigated by TD-DFT. Experimental data from cyclic voltammetry, UV-visible spectroscopy, photochemical and photophysical experiments were compared to the theoretical data to discover the influence of L on the electronic transitions and to interpret the differences between the photochemical behaviors of these complexes. Cálculos de orbitais moleculares para o complexo cis-[Ru(bpy)2Lx](PF6) 2, onde bpy é 2,2'-bipiridina e L é 3-aminopiridina (complexo 1 com x = 2), foram realizados com o programa Gaussian 03 usando o método DFT. A estrutura eletrônica e as propriedades moleculares de 1 foram caracterizadas no vácuo e em solução com acetonitrila e comparadas com os resultados obtidos para o complexo com L = 5,6-bis(3-amidopiridina)-7-oxanorborneno (complexo 2 com x = 1). Os espectros eletrônicos dos complexos 1 e 2 foram investigados por TD-DFT. Os dados experimentais de voltametria cíclica, UV-vis, fotoquímica e fotofísica foram comparados com dados teóricos de maneira a estabelecer a influência de L nas transições eletrônicas e interpretar as diferenças entre os comportamentos fotoquímicos desses complexos.

The ruthenium complex, trans-[Ru(Bz)(NH 3) 4SO 2](CF 3SO 3) 2 1, Bz = benznidazole ( N-benzyl-2-(2-nitro-1 H-imidazol-1-yl)acetamide), is more hydrosoluble and more active (IC 50try/1 h = 79 +/- 3 microM) than free benznidazole 2 (IC 50try/1 h1 mM). 1 also exhibits low acute toxicity in vitro (IC 50macrophages1 mM) and in vivo (400 micromol/kgLD 50600 micromol/kg) and the formation of hydroxylamine is more favorable in 1 than in 2 by 9.6 kcal/mol. In murine acute models of Chagas' disease, 1 was more active than 2 even when only one dose was administrated. Moreover, 1 at a thousand-fold smaller concentration than the considered optimal dose for 2 (385 micromol/kg/day = 100 mg/kg/day), proved to be sufficient to protect all infected mice, eliminating the amastigotes in their hearts and skeletal muscles as observed in HE micrographics.

This paper presents the synthesis, MO calculations, and photochemical and photophysical properties of cis-[Ru(bpy)2(3Amdpy2oxaNBE)](PF6)2 (2), where bpy is 2,2'-bipyridine and 3Amdpy2oxaNBE is the novel 5,6-bis(3-amidopyridine)-7-oxanorbornene chelate-ligand (1). Complex 2 is considered in relation to the cis-[Ru(bpy)2(3Amnpy)2](PF6)2 (3) analogous complex, where 3Amnpy is 3-aminopyridine. Complexes 2 and 3 exhibit absorptions near 350 nm and in the 420-500 nm region attributable to a contribution from MLCT transitions (dpi-->bpy and dpi-->L; L=3Amdpy2oxaNBE or 3Amnpy). Whereas complex 3 is photochemically reactive, complex 2 shows luminescence either at 77 K or at room temperature in fluid solution. The emission of 2 assignable as an MLCT (Ru-->bpy) emission is characterized by a long lifetime at room temperature (650 ns in CH3CN and 509 ns in H2O). It is independent of lambdairr, but it is temperature dependent; i.e., it increases as the temperature is lowered. Considering the chelate ring of 1 contributes to the stability of the complex 2 under continuous light irradiation, the difference in the primary photoprocesses of 3 (loss of 3Amnpy) and 2 (luminescence) may be caused by a lowering of the lowest excited state from 3 to 2. The surface crossing to the lowest MC state value of 987 cm-1 (similar to that of [Ru(bpy)3]2+) will be prevented in the case of complex 2, and as a result, efficient 3Amdpy moiety loss cannot occur. The electronic depopulation of the {Ru(bpy)2} unit and population of a bpy* orbital upon excitation are evident by comparing the photophysical properties with those of a [Ru(bpy)3]2+ related complex. Moreover, a reduction of a bpy ligand in the MLCT excited state is indicated by time-resolved spectra that show features typical of bpy*-. The photocatalytic property of 2 is spectroscopically demonstrated by oxidative quenching using either methylviologen2+ or [RuCl(NH3)5]+2 electron-acceptor ions.

In this Letter, we present the investigation of the potential energy surface for the ONO–NO 2 molecule and the asymmetric dimerization of NO 2 by using the DFT/B3LYP methodology. The torsion energy of the ONO–NO 2 isomer is 1.7 kcal mol −1 . The asymmetric dimerization of NO 2 is barrierless with an energy well of 19.8 kcal mol −1 . By using the polarizable continuum model, the NO 2 asymmetric dimerization in aqueous phase may be slightly spontaneous. From this study, we suggest that this reaction is likely to occur in aqueous phase of polluted environments.

A detailed theoretical study of the 1,7,1l,17-tetraoxa-2,6,12,16-tetraaza-cycloeicosane ligand ([20]AneN4O4) coordinated to Fe2+, Co2+, Ni2+, Ru2+, Rh2+, and Pd2+ transition metal ions was carried out with the B3LYP method. Two different cases were performed: when nitrogen is the donor atom (1aq) and also with the oxygen as the donor atom (1bq). For all the cases performed in this study 1aq structures were always more stable than the 1bq ones. Considering each row is possible to see that the energy increases with the increase of the atomic number. The M2+ cation binding energies for the 1aq complexes increase with the following order: Fe2+ < Ru2+ < Co2+ < Ni2+ < Rh2+ < Pd2+.

355 nm light irradiation of fac-[Mn(CO)3(phen)(imH)]+ (fac-1) produces the mer-1 isomer and a long lived radical which can be efficiently trapped by electron acceptor molecules. EPR experiments shows that when excited, the manganese(I) complex can be readily oxidized by one-electron process to produce Mn(II) and phen −. In the present study, DFT calculations have been used to investigated the photochemical isomerization of the parent Mn(I) complex and to characterize the electronic structures of the long lived radical. The theoretical calculations have been performed on both the fac-1 and mer-1 species as well as on their one electron oxidized species fac-1+ and mer-1+ for the lowest spin configurations (S = 1/2) and fac-6 and mer-6 (S = 5/2) for the highest one to characterize these complexes. In particular, we used a charge decomposition analysis (CDA) and a natural bonding orbital (NBO) to have a better understanding of the chemical bonding in terms of the nature of electronic interactions. The observed variations in geometry and bond energies with an increasing oxidation state in the central metal ion are interpreted in terms of changes in the nature of metal–ligand bonding interactions. The X-ray structure of fac-1 is also described.

The complex trans-[Ru(NO)(NH3)4{P(OEt)3}](PF6)3 undergoes nucleophilic attack on the phosphorus ester ligand in the solid state yielding trans-[Ru(NO)(NH3)4{P(OH)(OEt)2}](PF6)3. The reaction was monitored and the products analyzed using nuclear magnetic resonance spectroscopy (31P{¹H} CP-MAS NMR and 31P{¹H} NMR), infrared spectroscopy (FTIR), electron paramagnetic resonance spectroscopy (EPR), cyclic voltammetry (CV), electronic spectroscopy (UV-Vis) and elemental analysis. According to experimental data and quantum mechanical calculations (DFT), the reaction proceeds in the solid state by the nucleophilic attack on the phosphorus ligand, promoted by the strong polarization along the P III-RuII-NO+ axis induced by the nitrosyl ligand, and takes place following the Michaelis-Arbusov type mechanism for phosphorus ester hydrolysis. In solution, the nucleophilic attack occurs simultaneously at the nitrosyl and triethylphosphite ligands, yielding trans-[Ru(H2O)(NH3)4{P(OEt)3}]2+ and trans-[Ru(NO)(H2O)(NH3)4]3+ in comparable amounts. Neste trabalho foi investigado o ataque nucleofílico sofrido no estado sólido pelo complexo trans-[Ru(NO)(NH3)4{P(OEt)3}](PF6)3, no éster de fósforo coordenado, originando como produto a espécie trans-[Ru(NO)(NH3)4{P(OH)(OEt)2}](PF6)3. A reação foi monitorada e os produtos caracterizados utilizando ressonância magnética nuclear (31P{¹H} CP-MAS NMR e 31P{¹H} NMR), espectroscopia no infravermelho (FTIR), ressonância paramagnética eletrônica (EPR), voltametria cíclica (CV), espectroscopia eletrônica (UV-Vis) e análise elementar. De acordo com os dados experimentais e cálculos de mecânica quântica (DFT), a reação ocorre no estado sólido pelo ataque nucleofílico no éster de fósforo coordenado devido à forte polarização no eixo P III-RuII-NO+ induzida pela presença do ligante nitrosilo. A reação segue o mecanismo tipo Michaelis-Arbusov para hidrólise de ésteres de fósforo. Em solução (pH 7,0), o ataque nucleofílico ocorre nos ligantes NO+ e P(OEt)3, gerando como produtos os complexos trans-[Ru(H2O)(NH3)4{P(OEt)3}]2+ e trans-[Ru(NO)(H2O)(NH3)4]3+ em proporções comparáveis.

Quantum chemical calculations were performed in order to obtain molecular properties such as electronic density, dipole moment, atomic charges, and bond lengths, which were compared to qualitative results based on the theories of the organic chemistry. The quantum chemistry computational can be a useful tool to support the main theories of the organic chemistry.