Theoretical Investigations of the Herbicide Glyphosate Adsorption on the B12N12 Nanocluster

Nowadays is emergent the development of new materials which can be used in the adsorption process to remove herbicide glyphosate from the aquatic environment. Therefore, density functional theory (DFT) calculations were performed to study the adsorption process of the glyphosate on the B12N12 nanocage in aqueous media. The optimized structures of adsorbed glyphosate do not affect the nanocage structure indicating its structural stability. The chemisorption of this herbicide is an exothermic process with −43.89 kcal.mol-1. The most stable complex displayed an adsorption energy and ∆G values of −53.97 and −40.79 kcal.mol-1, respectively. The HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital) energies are located in the glyphosate implying that this herbicide can be removed by chemical reaction. Our results show that the B12N12 nanocluster can be a suitable new nanomaterial to remove the glyphosate from wastewater. DOI: http://dx.doi.org/10.17807/orbital.v9i3.99

A New Complex of Palladium(II) With 2-Furoic Hydrazide: Synthesis, Characterization, Theoretical Calculations and Biological Studies

A new complex of palladium was isolated with 2-furoic hydrazide (FH) and characterized by spectroscopic methods. The results show that the ligand is coordinated to palladium by the basic nitrogen of NH2 group and has a general structure of type cis-[Pd(FH)2Cl2]. The structure of palladium(II) complex was optimized and theoretical data show good agreement with the experimental results. The cytotoxic activity was evaluated in a chronic myelogenous leukemia cell line, which revealed that the compound is less active than cisplatin or carboplatin. At 300 g mL−1, the complex presented antimicrobial activity more efficient than ampicillin, chloranfenicol and kanamicyn. (doi: 10.5562/cca2151

Crystallographic study of platinum (II) and nickel (II) compounds with dithiocarbimate

Dithiocarbamate salts and its complexes are well known because of their wide range of applications. For example, dithiocarbamate and derivatives are very active accelerators in rubber vulcanization. Many dithiocarbamates, anions and complexes, show biological activity and are used as fungicides and bactericides. Besides being less investigated, interest in the synthesis and characterization of dithiocarbimate metal complexes is due to their similarity with dithiocarbamates. The nickel(II) and platinum(II) bisditiocarbimate complexes are necessarily anionic species. Thus, the use of active counter ions could improve their biological activity. In the present work, the structural elucidation, by X-ray diffraction, is presented of two novel platinum(II) and three novel nickel(II) compounds with the R-ditiocarbimate anion: tetra-n-butylammonium bis(2,5-dichlorophenylsulphonyldithiocarbimato) nickelate(II) (NIDBU), tetra-n-butylammonium bis(4-iodophenylsulphonyldithio carbimato)nickelate(II) (NIBBU), tetra-n-butylammonium bis(ethylsulphonyldithio carbimato)nickelate(II) (NIJBU), tetra-n-butylammonium bis(phenylsulphonyldithio carbimato)platinate(II) (PTB) and tetra-n-butylammonium bis(4-bromophenyl sulphonyldithiocarbimato)platinate(II) (PT2F1). The compounds studied are constituted by two tetra-n-butylammonium cations and one complex anion. The metallic atom is coordinated by 4 sulfur atoms of two R-sulfonyldithiocarbimato ligands, in a distorted square-planar configuration. With the exception of NIBBU, in all other compounds the metallic atom crystallizes in an inversion center. The complex anion geometry mainly depends on the R group of the R-sulfonyldithiocarbimato ligand. The crystal packing of the 5 compounds presents weak interactions as Csp3-H...X (X = O, N e/ou S e Cl) between the cátion and the complex anion.Dissertação (Mestrado)Sais e complexos de ditiocarbamato são compostos bem conhecidos por suas amplas e variadas aplicações. Por exemplo, ditiocarbamato e seus derivados são muito ativos como aceleradores de vulcanização da borracha. Muitos ânions e complexos de ditiocarbamato apresentam atividade biológica e são usados como fungicidas e bactericidas. Além de terem sido pouco estudados, o interesse na síntese e caracterização de complexos metálicos de ditiocarbimatos é devido às suas similaridades com compostos de ditiocarbamatos. Complexos de níquel(II) e de platina(II) com bisditiocarbimatos são espécies aniônicas e a possibilidade de variar os contra-íons pode melhorar sua atividade biológica. No presente trabalho foi realizada a elucidação estrutural, por difração de raios-X, de cinco compostos inéditos, dois de platina(II) e três de níquel(II) com ditiocarbimato: bis(2,5-diclorofenilsufonilditiocarbimato)niquelato(II) de tetrabutilamônio (NIDBU), bis(4-iodofenilsufonilditiocarbimato)niquelato(II) de tetrabutilamônio (NIBBU), bis(etilsufonilditiocarbimato)niquelato(II) de tetrabutilamônio (NIJBU), bis(fenilsufonilditiocarbimato)platinato(II) de tetrabutilamônio (PTB) e bis(4-bromofenilsufonilditiocarbimato)platinato(II) de tetrabutilamônio (PT2F1). Todos os compostos estudados são constituídos por dois cátions tetrabutilamônio e um ânion complexo. O átomo metálico está coordenado por 4 átomos de enxofre de dois ligantes R-sulfonilditicarbimato, numa geometria quadrado planar distorcida. Com exceção do composto NIBBU, os demais cristalizam com o átomo metálico localizado em um centro de inversão. A geometria do ânion complexo depende, principalmente, do substituinte R do ligante R-sulfonilditiocarbimato. No empacotamento cristalino dos 5 compostos estão presentes interações fracas do tipo Csp3-H...X (X = O, N e/ou S e Cl) entre o cátion e o ânion complexo

MOLECULAR CHARACTERIZATION OF BIOPOLIMERS IN SOLUTION BY COMPUTATIONAL SIMULATION

Computer simulation methods were used to characterize the structure and molecular properties of natural and synthetic biopolymers in aqueous solution. The polysaccharides chitin and chitosan, and aliphatic polypeptides were studied. The interest on the chitin and chitosan biopolymers is because of their biodegradability, biocompatibility and potential use as pharmaceutical and technological product. Molecular dynamics simulations have been used to characterize the structure and the solubility of the chitins and chitosans in aqueous solution. The simulated systems were composed by solvated chains, and nanoparticles composed by chains packed in a parallel and anti-parallel fashion, with different percentage and distribution of acetyl groups. The 100% acetylated chitin, whether isolated or in the form of α/β-chitin, adopt the 2-fold helix conformation with φ and ψ values similar to those on crystalline state. The ionic strength affects the kinetics, but not the conformational equilibrium. In solution, the intramolecular hydrogen bond HO3(n)···O5(n+1) responsible for the 2-fold helical motif is stabilized by hydrogen bonding to water molecules in a well-defined orientation. On the other hand, chitosan with small percentage and random distribution of acetil groups can adopt five distinct helical motifs and its conformational equilibrium is highly dependent on pH. The hydrogen bond pattern and solvation around the O3 atom of insoluble chitosan (basic pH) are nearly identical to those quantities in chitin. Chitin and chitosan nanoparticles with block distribution of acetyl groups favor the formation of intermolecular hydrogen bonds and hydrophobic interactions, resulting in more stable aggregates. The water mobility and orientation around polysaccharide chain (highly affected by electrostatic forces) is responsible for the aggregation and solubility of the chitin and chitosan biopolymers. Moreover, a sequential QM/MM methodology is used to study the α-helix stability of aliphatic polypeptides in water solution. The understanding of the folding process is one of the greatest challenges of biophysics, and the first step is the understanding of the formation and stabilization of the secondary structure of a polypeptide. The calculated heat of formation and free energy of solvation showed that the size of side chain is directly related to the α-helix stability. The results suggest that the helix-coil transition of a polypeptide is governed by the equilibrium between the energy used in the folding process and the energy released in the solvation process, showing the solvent effect on α-helix stabilization. The validation of the sequential QM/MM methodology showed that this method is suitable to study the helix-coil transition of polypeptides in solution. The methodology is therefore useful to study solvation effects on the properties of compounds with many conformational degrees of freedom.Universidade Federal de Sao CarlosNeste trabalho, métodos de simulação computacional foram usados para caracterizar a estrutura e propriedades moleculares de biopolímeros naturais e sintéticos em solução aquosa. Os polissacarídeos quitina e quitosana, e polipeptídeos alifáticos foram os biopolímeros estudados. O interesse nos biopolímeros quitina e quitosana é devido à suas biodegradabilidade, biocompatibilidade e potencial uso como produto farmacêutico ou tecnológico. No presente trabalho, simulações por Dinâmica Molecular foram utilizadas para caracterizar a estrutura e a solubilidade de quitinas e quitosanas em solução aquosa. Os sistemas modelados eram compostos por cadeias solvatadas e nanopartículas formadas por cadeias empacotadas paralelamente e de forma antiparalela, com diferentes percentagens e distribuição de grupos acetil. A quitina 100% acetilada, tanto na forma isolada ou na forma de α/β-quitina adota a conformação de hélice 2, com valores de φ e ψ similares aos da sua estrutura cristalina. A força iônica afeta a cinética, mas não o equilíbrio conformacional. Em solução, as ligações de hidrogênio intramolecular HO3(n)···O5(n+1), responsável por estabilizar o motivo helicoidal hélice 2, são estabilizadas por ligações de hidrogênio com moléculas de água em orientações bem definidas. Por outro lado, a quitosana com pequena percentagem e distribuição randômica de grupos acetil pode adotar cinco motivos estruturais e seu equilíbrio conformacional é altamente dependente do pH. O padrão de ligação de hidrogênio e a solvatação ao redor do átomo O3 da quitina insolúvel (pH básico) é quase idêntico ao observado para a quitina. As nanopartículas de quitina e quitosana com distribuição em blocos de grupos acetil favorece a formação de ligações de hidrogênio intermolecular e interações hidrofóbicas, resultando em agregados mais estáveis. A mobilidade e a orientação das moléculas de água ao redor da cadeia de polissacarídeo (altamente afetada por forças eletrostáticas) é responsável pela agregação e solubilidade dos biopolímeros quitina e quitosana. Além disso, a metodologia QM/MM sequencial foi utilizada para estudar a estabilidade da α-hélice de polipeptídeos alifáticos em solução. Sabe-se que o entendimento do processo de enovelamento é um dos grandes desafios da biofísica, e o primeiro passo consiste em entender a formação e a estabilização da estrutura de polipeptídeos. Os valores de calor de formação e energia livre de solvatação mostraram que o tamanho da cadeia lateral é diretamente proporcional à estabilidade da α-hélice. Os resultados sugerem que o processo de enovelamento-desenovelamento de polipeptídeos é governado pelo equilíbrio entre a energia utilizada para enovelar o peptídeo e a energia liberada pelo processo de solvatação, mostrando o efeito do solvente na estabilização da α-hélice. A validação da metodologia QM/MM sequencial utilizada mostrou ser adequada para o estudo do processo de enovelamento desenovelamento de polipeptídeos em solução, e útil no estudo da estrutura eletrônica e do efeito do solvente em compostos que possuam elevado grau de liberdade conformacional

Syntheses, crystal structure and theoretical investigation of novel heteroleptic complexes of nickel(II) with N-R-sulfonyldithiocarbimate and phosphine ligands

Five new complexes of general formula: [Ni(RSO(2)N=CS(2))(dppe)], where R = C(6)H(5) (1), 4-ClC(6)H(4) (2), 4-BrC(6)H(4) (3), 4-IC(6)H(4) (4) and dppe = 1,2-bis(diphenylphosphino) ethane and [Ni(4-IC(6)H(4)SO(2)N=CS(2))(PPh(3))(2)] (5), where PPh3 = triphenylphosphine, were obtained in crystalline form by the reaction of the appropriate potassium N-R-sulfonyldithiocarbimate K(2)(RSO(2)N=CS(2)) and dppe or PPh(3) with nickel(II) chloride in ethanol/water. The elemental analyses and the IR, (1)H NMR, (13)C NMR and (31)P NMR spectra are consistent with the formation of the square planar nickel(II) complexes with mixed ligands. All complexes were also characterized by X-ray diffraction techniques and present a distorted cis-NiS(2)P(2) square-planar configuration around the Ni atom. Quantum chemical calculations reproduced the crystallographic structures and are in accord with the spectroscopic data. Rare C-H center dot center dot center dot Ni intramolecular short contact interactions were observed in the complexes 1-5. (C) 2011 Elsevier B. V. All rights reserved.CNPqConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG)FAPEMI

Preparation, crystal structure and spectroscopic characterization of nickel(II) complexes with dithiocarbimate derivated of sulfonamides

This work describes the syntheses of three compounds containing [Ni(RSO2N=CS2)2]^2 anions: (Bu4N)2[Ni(CH3CH2SO2N=CS2)2] (1), (Bu4N)2[Ni(4-IC6H4SO2N=CS2)2] (2) and (Bu4N)2[Ni(2,5-Cl2C6H3SO2N=CS2)2] (3). They were obtained in the crystalline form by the reaction of the appropriate potassium N-R-sulfonyldithiocarbimate (RSO2N=CS2K2) with nickel(II) chloride hexahydrate in methanol/water. Elemental analyses were consistent with the proposed formulae. UV–Vis and IR data are consistent with the formation of nickel–sulfur diamagnetic planar complexes. The 1H NMR and 13C NMR spectra showed the expected signals for the tetrabutylammonium cation and the dithiocarbimate moieties. Single crystal structure analyses showed that 1 crystallizes in the monoclinic space group P21/n, 2 crystallizes in the monoclinic space group P21/c and 3 crystallizes in the triclinic space group Pī. In these compounds the Ni. atom is coordinated to four S atoms in a distorted square plane geometry due to the asymmetric bidentade chelation by each ligand

Anatomical terminology of the internal nose and paranasal sinuses: cross-cultural adaptation to Portuguese

Introduction: Functional endonasal endoscopic surgery is a frequent surgical procedure among otorhinolaryngologists. In 2014, the European Society of Rhinology published the “European Position Paper on the Anatomical Terminology of the Internal Nose and Paranasal Sinuses”, aiming to unify the terms in the English language. We do not yet have a unified terminology in the Portuguese language. Objective: Transcultural adaptation of the anatomical terms of the nose and paranasal cavities of the “European Anatomical Terminology of the Internal Nose and Paranasal Sinuses” to Portuguese. Methods: A group of rhinologists from diverse parts of Brazil, all experienced in endoscopic endonasal surgery, was invited to participate in the creation of this position paper on the anatomical terms of the nose and paranasal sinuses in the Portuguese language according to the methodology adapted from that previously described by Rudmik and Smith. Results: The results of this document were generated based on the agreement of the majority of the participants according to the most popular suggestions among the rhinologists. A cross-cultural adaptation of the sinonasal anatomical terminology was consolidated. We suggest the terms “inferior turbinate”, “nasal septum”, “(bone/cartilaginous) part of the nasal septum”, “(middle/inferior) nasal meatus”, “frontal sinus drainage pathway”, “frontal recess” and “uncinate process” be standardized. Conclusion: We have consolidated a Portuguese version of the European Anatomical Terminology of the Internal Nose and Paranasal Sinuses, which will help in the publication of technical announcements, scientific publications and the teaching of the internal anatomical terms of the nose and paranasal sinuses in Brazil. Resumo: Introdução: A cirurgia endoscópica funcional endonasal é um procedimento cirúrgico frequente entre os otorrinolaringologistas. Em 2014, a Sociedade Europeia de Rinologia publicou o “Documento Europeu para Posicionamento sobre a Terminologia Anatômica Interna do Nariz e das Cavidades Paranasais” com o objetivo de unificar os termos na língua inglesa. Ainda não dispomos de uma terminologia unificada na língua portuguesa. Objetivo: Adaptação transcultural dos termos anatômicos do nariz e das cavidades paranasais para o português da “European Anatomical Terminology of the Internal Nose and Paranasal Sinuses”. Método: Um grupo de rinologistas de todo o Brasil, com experiência em cirurgia endoscópica endonasal, foi convidado a participar da elaboração desse posicionamento sobre os termos anatômicos do nariz e das cavidades paranasais para o português conforme metodologia adaptada da previamente descrita por Rudmik e Smith. Resultados: Os resultados desse documento foram gerados a partir da concordância da maioria dos participantes conforme as sugestões mais populares entre os rinologistas. Uma adaptação transcultural da terminologia anatômica nasossinusal foi consolidada. Sugerimos que se busque uniformizar termos como “concha inferior”, “septo nasal”, “porção (óssea/cartilagionasa) do septo nasal”, “meato (médio/ inferior) nasal”, “via da drenagem do seio frontal”,“recesso frontal” e “processo uncinado”. Conclusão: Consolidamos uma versão adaptada em português da “European Anatomical Terminology of the Internal Nose and Paranasal Sinuses” que auxiliará a publicação de comunicados técnicos, publicações científicas e o ensino dos termos anatômicos internos do nariz e das cavidades paranasais no Brasil. Keywords: Cross-cultural adaptation, Anatomy, Nose, Paranasal sinus, Consensus, Palavras-chave: Adaptação transcultural, Anatomia, Nariz, Cavidades paranasais, Consens