Thermochemistry of organometallic reactions in solution: joint ITC and DFT study

The understanding of certain, still unknown, aspects of the chemical bond is made possible by new theoretical tools, particularly static DFT-D or DFT methods corrected for dispersion. These methods allow accounting for, in a physically relevant way, the effects of dispersion at medium and long distance [1]. For the further assessing the accuracy of static DFT-D calculations the providing of referential experimental data was found to be essential. It has been shown that Isothermal titration calorimetry (ITC) techniques can provide reliable thermodynamic parameters of reaction (enthalpy ΔHr, Gibbs free energy ΔGr and entropy ΔSr) [2], while some recent studies showed good agreement between experimental and theoretical results [2]. The study presented here sheds some light on the thermochemistry of reactions in solution by preforming ITC experiments in chlorobenzene and static DFT-D calculations. The study points out that, in cases where solvent molecules can interact significantly with molecules of reactants, an accounting for the explicit solvation is of crucial importance for agreement between experiment and theory. The results of various kinds of organometallic reactions will be presented in some details

Joint ITC and DFT Study of the Affinity of Some Lewis Bases to HIFP in Solution

HFIP, i.e. 1,1,1,3,3,3-hexafluoropropan-2-ol, was found to be an exceptional medium,[1] either as solvent or co-solvent, that allows many reactions to occur.[2-5] However, the exact role and mode of action of HFIP in various chemical transformations still remains elusive. Despite many reports dealing with water/HFIP complexes, little has been published on other molecular complexes of HFIP as well as on thermochemistry of the formation of such complexes.[6] Within this study the affinity of a series of eight different Lewis bases (3 sulfoxides, 3 Nsp2 pyridine derivatives, 1 aromatic amine, 1 cyclic aliphatic ether) to HFIP (as Lewis acid) is investigated experimentally by Isothermal Titration Calorimetry (ITC) and theoretically using static DFT-D calculations. Measured ITC association enthalpy values ΔHaITC spanned -9.3 kcal/mol - -14 kcal/mol. Computations including a PCM implicit solvation model produced similar exothermicity of association of all studied systems - ΔHa values ranging -8.5 – -12.7 kcal/mol. In general, most of interaction energy is due to the hydrogen bonding and not due to formation of significantly strong halogen bonds. An additional set of calculations combining implicit and explicit solvation by chlorobenzene of the reactants, pointed out the relatively low interference of the solvent with the HFIPbase complexation, which main effect is to slightly enhance the Gibbs energy of the HFIP-Lewis base association. It is speculated that the interactions of bulk HFIP with Lewis bases therefore may significantly intervene in catalytic processes not only via the dynamic miscrostructuration of the medium but also more explicitly by affecting bonds’ polarization at the Lewis bases

Primena prirodnih antimikrobnih jedinjenja u biološkoj zaštiti hrane

The use of certain micro-organisms, their metabolic products, as well as plant extracts, is based on the development of new technologies of biological conservation and protection, which application can contribute, on the one hand, to the standardization process of making food products with uniform and / or improved quality parameters, and on the other hand, the emergence of secure products with longer shelf-life. The quest for a natural alternative to food safety, in relation to the use of chemical substances, is one of the most important activities of the food industry which is determined by the request of modern consumer to consume a minimum of processed foods.Upоtrеbа оdrеđеnih mikrооrgаnizаmа, njihоvih mеtаbоličkih prоdukаtа, kао i bilјnih еkstrаkаtа prеdstаvlја оsnоvu rаzvоја nоvih tеhnоlоgiја biоlоškоg kоnzеrvisаnjа i zаštitе, čiја primеnа mоžе dоprinеti, s јеdnе strаnе, stаndаrdizаciјi prоcеsа izrаdе prеhrаmbеnih prоizvоdа sа uјеdnаčеnim i/ili unаprеđеnim pаrаmеtrimа kvаlitеtа, а sа drugе strаnе, nаstаnku bеzbеdnih prоizvоdа sа prоdužеnim rоkоm upоtrеbе. Potraga za prirodnom alternativom zаštitе hrаnе, u odnosu na upotrebu hemijskih supstanci, predstavlјa jednu od najvažnijih aktivnosti prehrambene industrije, koja je uslovljena zahtevom savremenih potrošača za konzumiranjem minimalno prerađene hrane

Benchmarking to DFT-d calculations by ITC experimental data

The London forces [1–3], or dispersion, are omnipresent in the nature. It constitutes an important part of the energy contribution to the stabilization of the tertiary structure of peptides, other natural polymers and the spontaneous coalescence of atomic aggregates or apolar molecules. The specifi city of the force of London is that it acts at long distances and it is always attractive, and it is therefore effective intramolecularly and determines in many situations the conformational behaviour of organic molecules and organometallics as well. It plays an essential role in chiral recognition and discrimination processes. The understanding of certain still unknown aspects of the chemical bond is made possible by new theoretical tools, particularly static DFT-D or DFT methods corrected for Dispersion. These allow to account for in a physically relevant way the effects of dispersion at medium and long distance [4]. For the further assessing the accuracy of static DFT-D calculations providing a referential of experimental data was found essential. It has been shown that ITC techniques can provide reliable reaction enthalpy ΔHr, Gibbs free energy of reaction ΔGr and reaction entropy ΔSr as well [5]. Some recent studies showed good agreement between experimental and theoretical results [6–8]. This study will shed some light on the thermochemistry of the reactions in solution by preforming ITC experiments in chlorobenzene, from one side, and static DFT-D calculations at different levels of theory, from another side (Fig. 1). By comparison of obtained results one could conclude on the excellent agreement between experimental and theoretical data, which could be promising for the further development and application of static DFT-D computational methods. As examples, the results of various organometallic reactions will be presented in some details [9]

Unusual biological behavior of femoral liposarcoma

Introduction Liposarcoma of a bone is a very rare tumor of the fatty marrow, originating from lipoblasts. Its frequency is 1:1000 of all bone tumors. The long bones and the lower extremities are predominantly affected, equally in males and females between 30 and 70 years of age. In the estimation of its biological behavior, histological graduation (G), the surgical localization of the tumor (T) and the presence or absence of metastases (M), are very important. A tumor with low grade differentiation, with transosseal propagation and metastases, has a poor prognosis. Surgical resection-amputation, chemotherapy and radiotherapy are the therapeutic methods of choice. Case outline Twelve years ago, in a 58-year old man, there was a radiologically diagnosed sarcoma in the lower part of the right femur manifested with painful swelling in that region. The high suprapatellar amputation was done. There was a histologically proved liposarcoma of a high grade of malignancy. According to the therapeutic protocol, chemotherapy and radiotherapy were applied. During the period of 12 years, the patient had a relapse on the stump, metastatic dissemination in the soft tissue of small pelvis twice, once in the left scapular region and in the inguinal lymph nodes, six operations and 8-year accumulation of metastatic deposits in the lung. Now, the patient feels relatively well, mobile, and walks 5 kilometres every day. Conclusion Unusual behaviour of the liposarcoma of high grade malignancy with which the patient has been living for 12 years, could be explained by the patient’s strong immunobiological system in the struggle to retain its vitality and mobility

Improving the District Heating System in Belgrade - Towards Smart Energy consumption

An efficient system of district heating is the element of a sustainable building that determines comfort interior microclimate. District heating supply exists in 55 towns in Serbia. In Belgrade 50% of apartments and houses are covered with it. At the moment, Public Utility Company “Beogradske elektrane” uses lump billing method for collection for heating per square meter of residential space. Such billing method does not reflect the actual consumption of heat energy of each residential building. Furthermore, tenants who live in buildings with high consumption until now had no incentive to improve the energy efficiency of their building. By payment according to the lump sum principle no one is stimulated to rationally use expensive energy, neither plants nor consumers. According to the Law on energy in Serbia, Law on efficient use of energy and the Decision on the heat supply in the city of Belgrade, PUC "Beogradske elektrane" is obliged to install measuring device for payment per kWh of heat energy supplied, regarding fairer distribution of payment costs and rational energy management as well as increase energy efficiency of the buildings. Generation plants are required to switch to reading of the central heat meters (located in the substations) and to calculate consumption of heat energy of each building individually. The paper considers measures to improving the District Heating System in Belgrade in order to perceive the reduction of heating energy consumption and environmental pollution. Two case studies are presented as comparative analysis of future costs of central heating for apartments - one in a building from 70-s without insulation and proper windows and another one built recently at the same area in Belgrade

ARCHITECTURE SOFTWARE SOLUTION TO SUPPORT AND DOCUMENT MANAGEMENT QUALITY SYSTEM

One of the basis of a series of standards JUS ISO 9000 is quality system documentation. An architecture of the quality system documentation depends on the complexity of business system. An establishment of an efficient management documentation of system of quality is of a great importance for the business system, as well as in the phase of introducing the quality system and in further stages of its improvement. The study describes the architecture and capability of software solutions to support and manage the quality system documentation in accordance with the requirements of standards ISO 9001:2001, ISO 14001:2005 HACCP etc

Ruptured hydatid cyst of the interventricular septum with acute embolic pulmonary artery complications

Hydatid cysts located in the interventricular septum are especially rare but with the high risk for intracavitary rupture. We report a patient with acute pulmonary embolism caused by an isolated, ruptured hydatid cyst on the right side of the interventricular septum. Early diagnosis was made by echocardiography and positive serology. Pulmonary artery embolism was confirmed by angiography and the patient was operated on. Embolectomy was performed by removing multiple fragments of ruptured endocyst from the left pulmonary artery, followed by surgical closure of a cyst cavity. Prompt diagnosis and an appropriate surgical treatment prevented a potentially fatal outcome