Simple Method for the Estimation of pKa of Amines

A simple and efficient model for the estimation of alkylamine basicities (through corresponding pKa values) is developed. Model uses partial atomic charges of hydrogen and of neighboring nitrogen cal-culated by MNDO-PM6 semiempirical model, taking into account the order of the substitution on nitrogen

Effect of light on the aging, corrosion, and degradation of materials, in relation to the enhanced removal of organic pollutants

A review on advanced photochemical processes influencing properties of materials is presented. Particular emphasis is given on photolytic processes for the removal of pollutants. Separately are presented methods for the removal of biological pollution. Major concern is paid to the methods for removal of persistent chemical pollutants. Two major groups of processes are known: homogenous and heterogeneous photocatalytic methods. The heterogeneous photocatalysis is usually done with semiconductor nanoparticles, capable to absorb light. In semiconductor the absorption of light quanta is connected with the promotion of electron(s) from valence to conduction band, leaving a positively charged hole(s) in CB. Electrons and holes can react with adsorbed molecules including water molecules. In this way the reactive intermediates are produced, which upon the sequence of reactions end with complete mineralization of ingredients. The scaling-up of heterogeneous photocatalytic process is closely connected with efficacy of them. As a matter of fact, many factors are involved in kinetics of photocatalysis: concentration of pollutants; concentration of catalyst; temperature; radiant flux; quantum yield; dopants; etc. The interrelations among various parameters are mostly nonlinear, and construction of the photoreactor is very demanding task. In last 30 years a lot of study was done, and general conclusion is that TiO2 (mostly anatase) is most efficient photocatalyst, but there is a lot of work needed on improvement of such processes

Računarski generisani molekulski deskriptori kao proxi-ji za modelovanje materijala i njihovog uticaja

For the prediction of material's properties and of interaction of molecules with the surroundings, one needs to know their properties. Usually, the molecular properties are revealed through experimental measurements. It can be a tedious, time-consuming, and costly work. On the other hand, computational chemistry readily generates a huge number of data which can provide various molecular descriptors. These can be various observable properties (bond lengths and angles, dipole moments, etc...), but also the unobservable properties (partial atomic charges, electronegativity, various latent variables ....). There is an urgent need to develop accurate and economical screening tools that predict potential toxicity and environmental burden of various chemicals. Equally important is the design of safer alternatives. Molecular modeling methods offer one of several complementary approaches to evaluate the risk to human health and the environment as a result of exposure to environmental chemicals. These tools can streamline the hazard assessment process by simulating possible modes of action and providing virtual screening tools that can help prioritize bioassay requirements. Tailoring these strategies to the particular challenges presented by environmental chemical interactions make them even more effective. Advances in the fields of computational chemistry and molecular toxicology in recent decades allow the development of predictive models that inform the design of molecules with reduced potential to be toxic to humans or to the environment. As an example we present the novel methodology for the computational evaluation of pKa values of various organic bases, based on calculation of partial atomic charges by a simple semiempirical QM method.Za predviđanje osobina materijala i njihove interakcije sa okolinom, treba poznavati njihove osobine. Obično se osobine molekula otkrivaju eksperimentalnim merenjima. To može biti mukotrpan dugotrajan i skup posao. Sa druge strane, računarska hemija lako daje veliki broj podataka koji mogu da obezbede različite deskriptore molekula. To mogu biti razne merljive veličine (dužine i uglovi veza, dipolni momenti, i sl...), ali i nemerljive osobine (parcijalna atomska naelektrisanja, elektronegativnost, razne latentne varijable ....). Postoji velika potreba za razvijanjem pouzdanih i ekonomičnih načina za skrininge kojima se predskazuje potencijalna otrovnost i opterećenje životne okoline raznim hemikalijama. Jednako važan je i dizajn bezbednijih alternativa. Metode molekulskog modelovanja nude jedan od nekoliko komplementarnih pristupa za procenu rizika za zdravlje ljudi i životne sredine kao posledicu izlaganja hemikalijama u okolišu. Ovim postupcima se može neprekidno vršiti procena opasnosti simuliranjem mogućih načina delovanja, a obezbeđivanje virtualnog skrininga može pomoći u određivanju prioriteta kod bio-eseja. Ukrajanjem ovih strategija u određene izazove interakcija hemikalija i životne sredine može iste učiniti efikasnijima. Napredak u računarskoj hemiji i molekulskoj toksikologiji postignut poslednjih decenija dozvoljava razvoj prediktivnih modela za racionalni dizajn molekula sa umanjenim potencijalom otrovnosti za ljude ili za životnu sredinu. Kao primer predstavljamo novu metodologiju za računarsko procenjivanje pKa vrednosti različitih organskih baza na osnovu izračunavanja parcijalnih atomskih naelektrisanja prostim semiempirijskim QM metodom

Fotohemijska aktivacija zagađivača vazduha i veza sa očuvanjem kulturnog nasleđa

It is well known that the exposition to air and weather markedly enhances derogation of all artifacts. In this report, the contribution of light (particularly sunlight) to marked speed-up of the oxidation and other changes by exposition to atmosphere will be analyzed. Five major mechanisms of the effect of insolation can be identified: 1. First is a trivial one – the heating effect which enhances all chemical processes. 2. Photoexcitation of material from which the item is made, turning it more reactive toward air oxygen (and to other present substances). 3. Sensitization of oxygen by excitation to singlet state in which it is extremely reactive, and can react even with inert materials. 4. Photochemical transformation of volatile organic compounds (VOC), primarily aldehydes and ketones, that can with oxygen yield organic acids and hydroperoxides which definitely harm majority of materials. 5. In contact of oxygen and another material, upon the absorption of light quanta, a charge transfer process can occur, giving yield to pairs of ion-radicals, which further can be transformed in various reactive products.Dobro je poznato da izloženost vazduhu i vremenskim prilikama dovodi do značajnog narušavanja stanja svih rukotvorina. U ovom radu ćemo anaizirati uticaj svetlosti (naročito sunčeve svetlosti) na značajno ubrzanje oksidacije i drugih promena kao posledica izloženosti atmosferskim prilikama. Može se identifikovati pet glavnih mehanizama efekta insolacije:1. Prvi je trivijalni- uticaj zagrevanja koji ubrzava sve hemijske procese 2. Fotoekscitacija materijala od koga je predmet izrađen, što ga čini reaktivnijim prema kiseoniku iz vazduha( i drugim prisutnim supstancama). 3. Senzibilizacija kiseonika putem ekcitacije u stanje singleta u kojem je on ekstremno reaktivan i može reagovati čak i sa inertnim materijalima.4. Fotohemijska transformacija isparljivih organskih jedinjenja(VOC), prvensveno aldehida i ketona, koja sa kiseonikom mogu dati organske kiseline i hidroperokside koji definitivno oštećuju većinu materijala. 5. U dodiru sa kiseonikom i nekim drugim materijalom, nakon apsorpcije kvantuma svetlosti može doći do procesa prenosa naelektrisanja, što dovodi do parova jon-radikala, koji se dalje mogu transformisati u razne reaktivne produkte

Konformaciona analiza tri germakranolida PM3 semi-empirijskom metodom

The conformations of the C-6 lactomized germacranolides 1-3 were calculated by applying the PM3 semi-empirical method, The low-temperature H-1-NMR spectra of parthenolide (1) were also measured. The relations between the calculated and the experimentally determined geometries were established using a modified Karplus equation. The applied quantum-chemical calculations proved to be an efficient and easy-to-use tool for die elucidation and prediction of die properties of germacranolide-type sesquiterpene lactones.Konformacije germakranolida 1–3, laktonizovanih u položaju (6), izračunate su primenom PM3 semi-empirijske MO metode. Takođe su snimljeni protonski NMR spektri partenolida (1) na niskim temperaturama. Pomoću modifikovane Karplusove jednačine je uspostavljena korelacija između eksperimentalno utvrđenih i izračunatih najstabilnijih konformacija. Zaključeno je da primenjena kvantno-hemijska izračunavanja brzo i pouzdano mogu predvideti i objasniti osobine seskviterpenskih laktona tipa germakranolida

Umanjeno preživljavanje neoplastičkih humanih HeLa ćelija supstituisanim (E)-b-(benzoil) akrilnim kiselinama

The bacteriostatic activity of some of alkyl substituted (E)-β-(benzoyl)acrylic acids was shown earlier. The aim of this study was to investigate the antiproliferative action of 19 alkyl-, or halogeno-, or methoxy-, or acetamido-substituted (E)-β-(benzoyl)acrylic acids, against human cervix carcinoma, HeLa, cells. Target HeLa cells were continuously treated with increasing concentrations of substituted (E)-β-(benzoyl)acrylic acids during two days. The MTT test was used for assessment of the antiproliferative action of this group of compounds. Treatment of HeLa cells with 4-methyl-, 4-fluoro-, 4-chloro-, 4-bromo-and 4-methoxy-derivatives of (E)-β-(benzoyl) acrylic acid leads to the expression of cytostatic activity against HeLa cells (IC50 were in the range from 31-40 μM). Their antiproliferative action was less than that of the basic compound (E)-β-(benzoyl)acrylic acid whose IC50 was 28.5 μM. The 3,4-dimethyl-, 2,4-dimethyl-and 2,5-dimethyl-derivatives as well as the 4-ethyl-and 3,4-dichloro-and 2,4-dichloro-derivatives, have stronger cytostatic activity than the correspoding monosubstituted and parent compound. Their IC50 were 18.5 μM; 17.5 μM; 17.0 μM; 17.5 μM; 22.0 μM and 18 μM, respectively. The 4-iso-propyl-and 4-n-butyl-derivatives excited higher cytostatic activity than the compounds with a lower number of methylene -CH2-groups in the substitutent. Their IC50 were 14.5 μM and 6.5 μM respectively. The 2,5-di-iso-propyl-and 4-tert-butyl-derivatives expressed the most strong antiproliferative action against the investigated HeLa cells, IC50 being 4.5 μM and 5.5 μM, respectively. The investigated compounds affected the survival of HeLa cells, expressing a strong structure-activity relationship of the Hansch type.Još ranije je pokazana bakteriostatska aktivnost nekih alkil supstituisanih (E)-b-(benzoil)akrilnih kiselina. Cilj ovog rada je bio proučavanje antiproliferativnog dejstva 19 (E)-b-(benzoil)akrilnih kiselina, alkil-, ili halogeno-, ili metoksi-, ili acetamido-supstituisnaih, na ćelije humnog karcinoma grlića materice, HeLa ćelije. Ciljne HeLa ćelije, su kontinualno tretirane rastućim koncentracijama supstituisanih (E)-b-(benzoil)akrilnih kiselina tokom dva dana. MTT test je korišćen za utvrđanje antiproliferativnog dejstva ovog jedinjenja. Tretiranje HeLa ćelija 4-metil-, 4-fluoro, 4-hloro-, 4-bromo- i 4-metoksi-derivatima (E)-b-(benzoil)akrilne kiseline dovelo je do ispoljavanja citostatske aktivnosti prema HeLa ćelijama (IC50 su između 31.40 mM). Njihovo antiproliferativno dejstvo je bilo manje nego kod osnovnog jedinjenja, (E)-b-(benzoil)akrilne kiseline, čije IC50 je bilo 28,5 mM. 3,4-Dimetil-, 2,4-dimetil- i 2,5-dimetil- supstituisani, kao i 4-etil- te 3,4-dihloro-i 2,4- dihloro- derivati, imaju jaču citostatsku aktivnost od odgovarajućeg monosupstituisanog i osnovnog jedinjenja.Njihove IC50 vrednosti su 18,5 mM; 17,5 mM, 17,0 mM; 17,5 mM; 22,0 mMi18mM, u navedenom redosledu. 4-iso-Propil- i 4-n-butil-derivati pokazuju višu citostatsku aktivnost od jedinjenja sa manjim brojem metilenskih –CH2. grupa u supstituentu. Wihove IC50 vrednosti su 14,5 mM odnosno 6,5 mM. 2,5-Di-iso-propil- i 4-tert-butil- derivati ispoqavaju najjače antiproliferativno dejstvo prema ispitivanim HeLa ćelijama, IC50 su 4,5 mM i 5,5 mM u navedenom redosledu. Proučavana jedinjenja utiču na pre.ivqavawe HeLa ćelija, ispoljavajunji izrazitu relaciju Hanschovog tipa između strukture i biološke aktivnosti

Supplementary data for article: Cvijetić, I.; Vitorović-Todorović, M. D.; Juranić, I. O.; Drakulić, B. J. Reactivity of (E)-4-Aryl-4-Oxo-2-Butenoic Acid Arylamides toward 2-Mercaptoethanol. A LFER Study. Monatshefte Fur Chemie 2013, 144 (12), 1815–1824. https://doi.org/10.1007/s00706-013-1084-6

Supplementary material for: [https://doi.org/10.1007/s00706-013-1084-6]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1441

Molekulsko-orbitalno proučavanje oksidacije fenola u hinole i epoksihinole

The MO study showed that the radical oxidation of phenols into quinols occurs readily. Further radical oxidation (in the m-CPBA/(BzO)(2)/hv system) of quinols occurs through appropriate biradical species with an activation energy of 79.5 kJ/mol yielding syn-epoxyquinols. The stereochemical outcome presented in this study is in full agreement with the experimental results.Molekulsko-orbitalnim proučavanjem potvrđeno je da lako dolazi do radikalske oksidacije fenola u odgovarajuće hinole. Daljom oksidacijom sistemom m-CPBA/(BzO)2/hν hinoli se preko biradikalskih reakcionih vrsta oksiduju u odgovarajuće epoksihinole. Izračunato je da aktivaciona energija ove reakcije iznosi 79.5 kJ/mol. Stereohemijske posledice naših izračunavanja su u potpunom skladu sa eksperimentalnim rezultatima

Supplementary data for the article: Vitorović-Todorović, M. D.; Koukoulitsa, C.; Juranić, I. O.; Mandić, L. M.; Drakulić, B. J. Structural Modifications of 4-Aryl-4-Oxo-2-Aminylbutanamides and Their Acetyl- and Butyrylcholinesterase Inhibitory Activity. Investigation of AChE-Ligand Interactions by Docking Calculations and Molecular Dynamics Simulations. European Journal of Medicinal Chemistry 2014, 81, 158–175. https://doi.org/10.1016/j.ejmech.2014.05.008

Supplementary material for: [https://doi.org/10.1016/j.ejmech.2014.05.008]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1808]Related to accepted version:[http://cherry.chem.bg.ac.rs/handle/123456789/2907

Supplementary data for the article: Cvijetić, I. N.; Tanç, M.; Juranić, I. O.; Verbić, T. Ž.; Supuran, C. T.; Drakulić, B. J. 5-Aryl-1H-Pyrazole-3-Carboxylic Acids as Selective Inhibitors of Human Carbonic Anhydrases IX and XII. Bioorganic and Medicinal Chemistry 2015, 23 (15), 4649–4659. https://doi.org/10.1016/j.bmc.2015.05.052

Supplementary material for: [https://doi.org/10.1016/j.bmc.2015.05.052]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1742]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3327