Wyniki wyszukiwania - BazTech

1

Raman scattering study of meloxicam molecule and DFT calculations of its possible conformers

Skonieczny Robert, Osmałek Tomasz, Froelich Anna, Wiśniewska Maria, Nowicka Ariadna B., Szybowicz Mirosław

Inżynieria Materiałowa

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2023

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Vol. 44, nr 5

16--25

EN

Celem przeprowadzonych badań dla meloksykamu (MLX) było uzyskanie informacji o możliwych izomerach konformacyjnych oraz stabilności termicznej wybranych konformerów MLX. Obliczenia z wykorzystaniem teorii funkcjonału gęstości (DFT) wskazują na cztery możliwe izomery konformacyjne, które zostały porównane z eksperymentalnym widmem ramanowskim leku. Otrzymane wyniki wskazują, że konformer meloksykamu obserwowany w analizowanej próbce jest stabilny w badanym zakresie temperatur.

PL

The aim of the performed studies for meloxicam (MLX) was to obtain information about possible conformational isomerism and the thermal stability of the selected conformers of MLX. Density functional theory (DFT) calculations show four possible conformational isomers which are compared to the experimental Raman spectrum of the drug. The obtained results indicate that the conformer of meloxicam observed in the analyzed sample is stable within the investigated temperature range.

2

Intermolecular interactions for two chosen anthracene derivatives

Kania Sylwester, Kuliński Janusz, Kościelniak-Mucha Barbara, Słoma Piotr, Wojciechowski Krzysztof

Scientific Bulletin. Physics / Lodz University of Technology

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2021

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Vol. 42

5--12

EN

The nature of intermolecular interactions for anthrone and anthraquinone differs due to the symmetry of substitution of the central benzene ring, i.e. anthrone substituted with only one keto group and anthraquinone substituted with two keto groups. In order to interpret the interactions among the molecules, the interaction energies between molecules in crystals were calculated using DFT B3LYP calculations. The results reveal the consistency between calculated “lattice energies” and theirs terms and thermodynamical properties as density, boiling point and melting point of examined compounds.

PL

Przeprowadzono obliczenia oddziaływań międzycząsteczkowych wykorzystując program CrystalExplorer17 z wykorzystaniem pakietu oprogramowania Gaussian09. Obliczenia DFT wykazały zgodność pomiędzy uzyskanymi wartościami energii „sieci krystalicznej” badanych związków i jej składowych z osobna a wybranymi do analizy doświadczanymi właściwościami termodynamicznymi jak gęstość materiału, temperatura wrzenia i temperatura topnienia badanych związków. Badania wykazały inny charakter oddziaływań zachodzących podczas procesu topnienia i podczas procesu wrzenia. Proces topnienia związany jest z całkowitą energią sieci. Temperatura wrzenia związana jest z zerwaniem odziaływań pomiędzy pojedynczymi cząsteczkami. Decydujące jest tu zerwanie oddziaływania dipolowego i dyspersyjnego.

3

Structure-activity of chelating depressants for chalcopyrite/pyrite separation: DFT study and flotation experiment

Li Mingyang, Lian De, Zhao Fugang, Tong Xiong, Wu Chaoyang, Gao Xiangpeng

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 6

102--112

EN

Three types of chelating depressants were studied for chalcopyrite/pyrite separation, including S-S, S-O, and O-O types, via density functional theory calculations and microflotation. The calculation results indicate that the depressant’s chelating atoms have large coefficient and great activity according to the molecular frontier orbital (HOMO and LUMO) and the orbital coefficients. For S-S type of depressant, S atom in both keto or enol forms won’t affect their HOMO and LUMO patterns and the orbital contributions. For S-O type, the presence of N atom in the ring structure of a molecular will increase the reactivity of O-Cu while weak S-Cu. For O-O type, the electron supply capacity of benzene ring is higher than strain chain, and atom N in strain chain increased their electron supply capacity. The microflotation results basically confirmed the prediction based on the calculation. The simulation results demonstrate that the interaction of a depressant with metals and minerals are affected obviously by the spatial structure and electronic structure of an atom in its molecular.

4

Electrical and thermal properties of anthrone

Kania Sylwester, Kuliński Janusz, Sikorski Dominik

Scientific Bulletin. Physics / Lodz University of Technology

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2020

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Vol. 41

43--51

EN

Electrical and thermal properties of anthrone Quantum-chemical density functional theorem (DFT) calculations indicate that the value of the reorganization energy indicates the possibility of efficient hole capture by the anthrone molecule during transport process of charge carriers. Differential scanning calorimetry (DSC) studies indicate the temperature stability of anthrone molecules above the melting point up to 164°C. The glass transition is determined at 153.7°C and melting point at 157.05°C.

PL

Obliczenia funkcjonału kwantowo-chemicznego (DFT) wskazują, że wartość energii reorganizacji wskazuje na możliwość efektywnego wychwytywania dziur przez cząsteczkę antronu podczas transportu nośników ładunku. Badania metodą różnicowej kalorymetrii skaningowej (DSC) wskazują na stabilność temperaturową cząsteczek antronu powyżej temperatury topnienia do 164°C. Temperaturę zeszklenia określono jako Tg = 153,7°C, a temperaturę topnienia jako Tc = 157,05°C.

5

A DFT study of reorganization energy of some chosen carbazole derivatives

Kania Sylwester, Kościelniak-Mucha Barbara, Kuliński Janusz, Słoma Piotr, Wojciechowski Krzysztof

Scientific Bulletin. Physics / Lodz University of Technology

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2020

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Vol. 41

33--42

EN

Strong efforts toward finding an organic semiconductor with a molecule characterized by a low charge transfer energy applying quantum-chemical calculations are undertaken. Density Functional Theory (DFT) calculations made for carbazole (Cz) and three isomers of benzocarbazole, benzo (a) carbazole (BaCz), benzo (b) carbazole (BbCz) and benzo (c) carbazole (BcCz) proves the possibility of lacking the growth of reorganization energy despite the molecule dimentions enlargement. Benzo(b)carbazole molecules with high longitudinal dimension of the rigid skeleton d = 9,05 Å posses the low value of reorganization energy for both hole and electron transport of 0,18 eV and 0,11 eV, respectively. We suggest that the reduction of reorganization energy may be related to the diminishing of intramolecular hydrogen interactions.

PL

W artykule przedstawiono wyniki obliczeń kwantowo-mechanicznych mających na celu poszukiwanie cząsteczki organicznego półprzewodnika charakteryzującego się niską energią transferu ładunku. Obliczenia z wykorzystaniem teorii funkcjonału gęstości (DFT) zostały wykonane dla karbazolu (Cz) i trzech izomerów benzokarbazolu, benzo(a)karbazolu (BaCz) , benzo(b)karbazolu (BbCz) i benzo(c)karbazolu (BcCz) dowodzą , że można uniknąć wzrostu energii reorganizacji cząsteczki tak dla przewodnictwa dziurowego jak i dla przewodnictwa elektronowego pomimo zwiększenia rozmiarów przestrzennych szkieletu aromatycznego cząsteczki. Cząsteczki benzo(b)karbazolu o największym rozmiarze podłużnym szkieletu d = 9,05 Å charakteryzują się najniższą energią reorganizacji dla przewodnictwa dziur λh = 0,18 eV oraz najniższą wśród izomerów benzokarbazolu energią reorganizacji dla przewodnictwa elektronowego λe = 0,11 eV. Analiza odległości pomiędzy wybranymi charakterystycznymi atomami wodoru pozwala przypuszczać, że zmniejszenie energi reorganizacji obserwowane dla benzo(b)- karbazolu jest związane ze zmiejszaniem wewnątrzcząsteczkowych oddziaływań pomiędzy sąsiadującymi atomami wodoru.

6

The origin of the interaction responsible for the difference of hole mobility of two derivatives of anthracene

Kania S., Kuliński J., Sikorski D.

Scientific Bulletin. Physics / Lodz University of Technology

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2018

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Vol. 39

27--35

EN

Hole mobility of the layers built from two anthracene derivatives differing in the substitution of the central benzene ring, i.e. anthrone substituted with only one keto group and anthraquinone substituted with two keto groups differs by one order of magnitude despite the fact that both have almost identical crystal structure. We ascribe this difference to existence of an additional intermolecular interaction arising in the layer of anthrone.

PL

Wykazano, w przypadku antronu i antrachinonu będących pochodnymi antracenu podstawionego w środkowym pierścieniu jedną lub dwiema grupami ketonowymi obserwuje się jedynie małe i prawie identyczne zmiany aromatycznej energii stabilizacji (w zakresie 1%). Oba rozpatrywane związki mają prawie identyczną strukturę krystaliczną. Jednakże ruchliwość dziur w antronie jest o jeden rząd wyższa niż w antrachinonie, niezależnie, czy jest badana w warstwach amorficznych, quasi-amorficznych czy też krystalicznych. Dlatego też jedynym źródłem obserwowanej doświadczalnie różnicy ruchliwości nośników ładunku może być obecność dużego momentu dipolowego cząsteczki antronu w porównaniu do małej wartości momentu dipolowego cząsteczki antrachinonu.

7

Mix-substituted phthalocyanines of a “push–pull”-type and their metal complexes as prospective nanostructured materials for optoelectronics

Usol'tseva N. V., Smirnova A. I., Kazak A. V., Giricheva N. I., Galanin N. E., Shaposhnikov G. P., Bodnarchuk V. V., Yablonskii S. V.

Opto-Electronics Review

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2017

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Vol. 25, No. 2

127--136

EN

To study the influence of structural features of phthalocyanine (Pc) derivatives on their physico-chemical properties in bulk and thin films, 23 new phthalocyanines with different quantity and ratio of donor (alkyloxy-groups, in fragment “A”) and acceptor (Cl-, in fragment “B”) substituents in one molecule of the A3B, ABAB and AABB types with varied length of alkyloxy-substituents and their metal complexes were designed and synthesized. A comparative analysis of spectral, mesomorphic and photoelectric properties of these mix-substituted phthalocyanines of a “push–pull” type was performed. It was shown that non-peripheral substitution by alkyloxy-fragments in hetero-substituted Pcs (similar to homo-substituted Pc) leads to red-shifting of the Q-band into near-IR region. The intensity of photoluminescence, position of peaks and their splitting are strongly connected with chemical structure of Pcs and the type of solvent. In contrast to non-mesogenic octyloxy-Pc (A4) having alkyloxy-substituents in non-peripheral positions, 22 of 23 synthesized compounds possess columnar mesomorphism. The change of donor–acceptor ratio can influence the type of mesophase. A new approach to the creation of materials for optoelectronics is proposed and implemented, which includes design of compounds possessing vitrification from mesophase with maintenance of a columnar order, absorption in the near IR-region of the spectrum and good performance electrophysical characteristics simultaneously.

8

Spin trapping studies of essential oils in lipid systems

Makarova K., Drązikowska K., Suska B., Zawada K., Wawer I.

Nukleonika

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2015

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Vol. 60, No. 3, part 1

461--468

EN

In the present work, we report the results of a spin trapping ESR study of four essential oils widely used for skin care products such as creams and bath salts. The studied essential oils are Rosmarini aetheroleum (rosemary), Menthae piperitae aetheroleum (mint), Lavandulae aetheroleum (lavender), and Thymi aetheroleum (thyme). Fenton reaction in the presence of ethanol was used to generate free radicals. The N-tert- -butyl-α-phenylnitrone (PBN) was used as a spin trap. In the Fenton reaction, the rosemary oil had the lowest effect on radical adduct formation as compared to the reference Fenton system. Since essential oils are known to be lipid soluble, we also conducted studies of essential oils in Fenton reaction in the presence of lipids. Two model lipids were used, namely 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dipalmitoyl-sn- -glycero-3-phosphocholine (DPPC). The obtained results suggested that in the presence of DOPC lipids, the •OH and PBN/•CHCH3(OH) radicals are formed in both phases, that is, water and lipids, and all the studied essential oils affected the Fenton reaction in a similar way. Whereas, in the DPPC system, the additional type of PBN/X (aN = 16.1 G, aH = 2.9 G) radical adduct was generated. DFT calculations of hyperfi ne splittings were performed at B3LYP/6-311+G(d,p)/EPR-II level of theory for the set of c-centered PBN adducts in order to identify PBN/X radical.

9

Mössbauer study of a tetrakis (pentafl uorophenyl) porphyrin iron (III) chloride in comparison with the fluorine unsubstituted analogue

Kaczmarzyk T., Dziedzic-Kocurek K., Rutkowska I., Dziliński K.

Nukleonika

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2015

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Vol. 60, No. 1

57--61

EN

Mössbauer investigations, in association with density functional theory (DFT) calculations, have been conducted for the molecular and electronic structures of iron (III) [tetrakis (pentafl uorophenyl)] porphyrin chloride [(F20TPP)Fe:Cl], as a Fe(III)-tetraphenylporphyrin complex containing chloride axial ligand and substituted hydrogen atoms by fl uorine ones in the four phenyl rings, in comparison with its fl uorine unsubstituted analogue [(TPP)Fe:Cl]. It was found that the parameters of Mössbauer spectra of both complexes are close to one another, and correspond to the high-spin state of Fe(III) ions, but they show the different temperature dependence and the quadrupole doublets in Mössbauer spectra show different asymmetry at low temperatures. Results of DFT calculations are analyzed in the light of catalytic activity of the halogenated complex.

10

Mössbauer spectroscopy of reduced forms of a Fe-tetraphenylporphyrine complex

Kaczmarzyk T., Rutkowska I., Dziliński K.

Nukleonika

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2015

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Vol. 60, No. 1

51--55

EN

Molecular and electronic structure changes during successive reduction of a Fe-tetraphenylporphyrin chloride [Fe(III)(TPP):Cl] complex are reported on the basis of Mössbauer spectroscopy and DFT calculations. It is established that the attachment of additional electrons to a neutral Fe(III)(TPP):Cl molecule leads to signifi cant shortening of Fe-N distances at the fi rst stage of the reduction Fe(III)(TPP):Cl →Fe(II)(TPP) and lengthening of these bonds at the second stage Fe(II)(TPP)→Fe(I)(TPP). Changes of other bond lengths of the porphyrin ring also appear but in less degree. Interaction of Fe(II) and Fe(I)(TPP) with tetrahydrofuran (THF) solvent is considered. Electron configuration of Fe(II)(TPP) corresponds to intermediate-spin (S = 1) state and in the case of Fe(I)(TPP) low-spin state (S = ½) is observed. Electron density distribution in Fe(II)- and Fe(I)(TPP) complexes, in association with Mössbauer data, is analyzed. Good correlation between experimental and theoretical results was obtained.

11

Crystal structures and conformers of CyMe4-BTBP

Lyczko K., Ostrowski S.

Nukleonika

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2015

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Vol. 60, No. 4, part 2

853--857

EN

The crystal structure of new conformation of the CyMe4-BTBP ligand (ttc) has been presented. The ttt conformer of this compound in a form of THF solvate has been also crystallized. The geometries of six possible conformations (ttt, ttc, tct, tcc, ctc and ccc) of the CyMe4-BTBP ligand have been modeled in the gas phase and in solutions (MeOH and H2O) by DFT calculations using B3LYP/6-31G(d,p) method. According to the calculations, in the three different media the conformers with trans orientation of the N atoms in the bipyridyl moiety are the most stable.

12

Konformacyjne właściwości modyfikowanych reszt aminokwasowych

Wałęsa R., Buczek A., Broda A.

Chemik

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2014

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Vol. 68, nr 4

329--334

PL

Konformacyjnie usztywnione aminokwasy są szeroko stosowane przy konstruowaniu peptydowych analogów o lepszych właściwościach farmako-kinetycznych. Jednym z sposobów modyfikacji peptydów jest wprowadzenie reszt a,b-dehydroaminokwasowych w łańcuch peptydowy. Podwójne wiązanie Ca=Cb usztywnia łańcuch boczny i umożliwia występowanie izomerii geometrycznej Z/E. Innym rodzajem modyfikacji jest zastąpienie amidowej grupy –NH grupą –NCH3, czyli tzw. N-metylowanie. Autorzy określili wpływ tych dwóch modyfikacji strukturalnych na konformację łańcucha peptydowego. Przeprowadzone badania pozwoliły ustalić, że reszta a,b-dehydrofenyloalaniny aminokwasów konformacji H. Wykazano również, że polarny rozpuszczalnik zwiększa wyraźnie udział konfiguracji cis wiązania amidowego w N-metylowanych peptydach.

EN

Conformationally constrained amino acids are widely used in the design of peptide analogues with better pharmacokinetic properties. One of the methods of peptide modification is the introduction of a, b -dehydroamino acid residues into peptide chain. The double bond Ca=Cb constrains side chain and enables occurrence of geometrical isomerism Z/E. The other type of modification is the replacement of amide group –NH with group –NCH3, i.e. so called N-methylation. The Authors have determined the impact of these two structural modifications on peptide chain conformation. Conducted research has lead to the conclusion that -dehydrophenylalanine residue has the ability to exhibit atypical for standard amino acids H conformation. It has also been shown that polar solvent clearly increase percentage of cis configuration of amide bond in N-methylated peptides.

13

Contemplation on the protonation of TEX

Türker L.

Central European Journal of Energetic Materials

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2014

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Vol. 11, no. 2

307--319

EN

The possibility of acid catalyzed decomposition of TEX, a well known explosive, is considered by investigating the stability of cations formed by protonation at different sites in the molecule. For this purpose, density functional theory has been employed at the B3LYP/6-31++G(d,p) and B3LYP/6-31G(d,p) levels. Various simple cations, as well as hydrogen-bridged cations of TEX and carbocations formed from protonated TEX, are considered which may undergo further acid catalyzed cleavage routes of the molecule.

14

Hydrogen Bonds in the 1:1 and 2:1 Complexes of 1-Methylquinolinium-3-carboxylate with Mineral Acids Studied by NMR, FTIR and Raman Spectra and DFT Calculations

Barczyński P., Szafran M.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 5

1061-1074

EN

The 1:1 and 2:1 complexes of 1-methylquinolinium-3-carboxylate (benzotrigonelline), 3QB, with HCl, HBr, HNO3, HClO4 and HBF4 have been synthesized and their FTIR, Raman, 1H and 13C NMR spectra have been analyzed. The 1:1 complexes with HCl and HBr crystallize as monohydrates and water molecule is localized between the betaine and counter-ions (Cl– and Br–). In the complexes with HNO3, HClO4 and HBF4 the anions are connected with the protonated 3QB via O–HźźźX– hydrogen bonds. The 2:1 complexes with HCl, HBr, HNO3 and HClO4 crystallize with one water molecule while with HBF4 as an hydrous. Their FTIR spectra show a broad and intense absorption in the 1500–400 cm–1 region, typical of hydrogen bonds shorter than 2.5 A. The water molecule in the 2:1 complexes, except perchlorate, forms hydrogen bonds with anions. The influence of counter-ions on proton and carbon-13 chemical shifts is very small and comparable with the experimental error. The protonation of 3QB causes deshielding of all protons and most carbons, except C-3, C-9 and COO, which are shielded. The 2:1 complexes in D2O dissociate to the 1:1 complexes and 3QB. Five 1:1 (2–6) and six 2:1 (7–12) complexes have been analyzed by the B3LYP/6-31G(d,p) calculations in order to determine the influence of conformation of COOH groups on hydrogen bond and homoconjugation.

15

Hydrogen Bonds and Electrostatic Interactions in N-(Ethoxycarbonylmethyl)-quinuclidinium Chloride Dihydrate

Dega-Szafran Z., Katrusiak A., Szafran M.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 5

723-735

EN

N-(Ethoxycarbonylmethyl)-quinuclidinium chloride crystallizes as dihydrate, QNBEźClź2H2O. The crystals are monoclinic, space group C2/c. Water molecules interact with the chloride an ions and form a cyclic oligomer, through the O–HźźźCl and O–HźźźO hydrogen bonds. The chloride an ions and water molecules addition ally interact electrostically with the positively charged nitrogen atom of the quinuclidinium moiety. The optimized structure of QNBEźClź2H2O by the B3LYP/6-31G(d,p) level of the ory reproduces well the molecular aggregation observed in the crystal. The FTIR spectrum of the solid compound is consistent with the X-ray structure.

16

Assembly of Protonated Tetramethylpyrazine (TMP) in Triiodide. Vibrational Spectra and DFT Simulations

Sobczyk L., Bator G., Sawka-Dobrowolska W., Nowicka-Scheibe J., Grech E., Pawlukojć A.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 5

957-963

EN

In the complex of tetramethylpyrazine (TMP) with HI3 two protonated molecules of TMP form the assembly of composition (TMP×H+)2TMP(I3 - )2. The X-ray structure, determined at 100 K, shows the +N-H×××N hydrogen bonds markedly shorter than those found previously [13] at room temperature (2.828 ni s. 2.894 A). The DFT calculations for isolated cation yield the value of 3.038 capital A, ring that reflects the soft ness of the hydroen bond potential. The calculations of vibrational frequencies for crystalline state reflect very well the IR spectra. This relates particularly to the ni (NH+) mode. A remark able discrepancy is observed when calculations are performed for isolated assemblies.

17

Modification of Tetraphenylporphyrin Ring in Manganese(III) Complexes - Theoretical Description of the Influence on Their Physicochemical Properties

Szaleniec M., Tokarz-Sobieraj R., Witko M.

Polish Journal of Chemistry

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2008

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Vol. 82, nr 9

1853-1863

EN

Metalloporphyrins are known to be efficient catalysts in oxidation of hydrocarbons. To understand a mechanism of oxidation processes de tailed knowledge of the electronic and structural parameters of these systems is required. Here, atomic parameters calculated by means of DFT method for the selected manganese porphyrins are correlated with experimental redox potential. The results of calculations carried out for systems with modification in phenyl substituents showed that charge of porphyrin ring and charge of axial ligand are good theoretical descriptors of effect introduced by the substituent. These descriptors correlate (R2 = 0.97) with experimental value of redox potential of the MnIII/MnII system.

18

Aktywacja cząsteczek organicznych przez jony Cu+ w zeolitach

Kukulska-Zając E., Kozyra P., Datka J.

Wiadomości Chemiczne

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2007

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[Z] 61, 11-12

839-890

EN

The present paper describes the activation of organic molecules containing multiple bonds by donation of electrons to ?* antibonding orbitals of the molecules. The data concerning the adsorption of alkenes (ethene, propene, cis-but-2-ene, trans--but-2-ene), acetylene, benzene, acetone, and formaldehyde on Cu+ sites in zeolites CuX, CuY, and CuZSM-5 will be presented. The spectroscopic IR data, as well as the results of quantum chemical DFT calculations will be considered. Both IR studies and DFT calculations evidenced a weakening of C=C and C-C bonds. IR red shift reaches 78-115 cm-1 for C=C band and 168 cm-1 for acetylene. Moreover, in the case of ethene and acetylene the stretching modes of the C=C and C-C bonds which were IR inactive in free molecules became IR active when interacting with Cu+, indicating the loss of symmetry. On the contrary, the C=C stretching in trans-but-2-ene was still IR inactive when trans-but-2-ene interacted with Cu+. At high loading some Cu+ ions were able to bond two alkene molecules. Although the activation is small, it occurs also for aromatic C-C bond in benzene adsorbed on Cu+ site; the red band shift was 13 cm-1 i.e. much less than in the case of alkenes and acetylene. Similarly, the activation of C=O bond in acetone and formaldehyde inter-acting with Cu+ also results in the red band shift of 38 and 56 cm-1.

19

The Role of Alkali and Alkaline Earth Metal Ions on the Hydrolysis of 2-Ferrocenyl-1,3-dioxane in Acetonitrile Solutions

Navarro E., González F., Astudillo P., Vázquez-Hernández M., Hernández-Rodríguez M., Juaristi E.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 5-6

921-930

EN

he hydrolysis of 2-ferrocenyl-1,3-dioxane in the presence of different alkali (Li+, Na+, K+ ), alkaline earth (Mg2+, Ca2+ ), and transition metal ions (Zn2+) was studied in acetonitrile solutions. The evolution of the hydrolysis of the dioxane ketalmoiety and the formation of the reaction products was monitored by analysis of the electrochemical oxidation potential of the ferrocenyl redox centre, which maintains its integrity in the reaction and facilitates the determination of the concentrations of both the starting material and products. It was found that only Ca2+ promotes the hydrolysis of 2-ferrocenyl- 1,3-dioxane to produce ferrocenecarboxaldehyde and 1,3-propanediol in up to quantitative yield when an excess of the Ca2+ metal ion is present. Theoretical calculations (B3LYP/3-21G*) led to a proposal for the hydrolysis mechanism, in which coordination of solvated calcium to theO–C–O dioxane segment is determinant for the process to begin.

20

Experimental and Density Functional Studies on Two Substituted 1H-Benzimidazoles

Zhao P., Yu H., Jian F., Wang X.

Polish Journal of Chemistry

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2007

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Vol. 81, nr 8

1511-1519

EN

Two substituted 1H-benzimidazoles, 2-(4-chlorophenyl)-1H-benzimidazole and 1-(2- chlorobenzyl)-2-(2-chlorophenyl)-1H-benzimidazole, have been synthesized and characterized by elemental analysis, IR and UV-Vis spectra. An extended MO calculations using density functional theory (DFT) at B3LYP/6-311G** level have been carried out on the two compounds. Comparison of the experiments with the calculated results suggests that the optimized geometries can well reproduce the molecular structures. Atomic charge distributions show that both of the title compounds are potential ligands to coordinate with metallic ions. Natural population analyses indicate that the electronic transitions corresponding to electronic spectra are mainly derived from the contribution of bands pi--pi*. Thermodynamic properties of the two title compounds at different temperatures have also been calculated on the basis of vibration analyses.