Wyniki wyszukiwania - Biblioteka Nauki

1

Synthesis and structural characterization of a series of transition metal complexes with a tetradentate Schiff-base ligand derived from salicylaldehyde and 2-(2-aminoethylamino)ethanol

100%

Mikuriya M. , Matsunami K.

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tom Vol. 23, No. 3

773--792

EN

A series of transition metal complexes with 1-[(2-hydroxyethyl)amino]-2-(salicylideneamino)ethane (H2hase), [V(Hhase)2]Cl (1), [VO2(Hhase)] (2), [Cr(Hhase)2]Cl (3), [Mn(Hhase)2]Cl (4), [Fe(Hhase)2]Cl (5), [Co(Hhase)2]Cl (6), [Co(Hhase)2]Br (7), [Co(Hhase)2]I (8), [Co(Hhase)2]NO3 (9), [Co(Hhase)2]NCS (10), [Co(Hhase)2]ClO4 (11), and [Co(Hhase)2]CH3CO2.H2O (12), have been synthesized by template reactions of salicylaldehyde and 2-(2-aminoethylamino)ethanol with metal salts and characterized by measurements of the infrared and electronic spectra, and magnetic moments. The molecular structures of these complexes were determined by the singlecrystal X-ray structure analysis. All the complexes except for 2 are mononuclear with an octahedral metal(III) ion, where the two Hhase ligands act a meridional tridentate chelate forming hydrogen bondings with counter anion. The two Hhase ligands are arranged so that the imino-nitrogen atoms are trans while the phenoxo-oxygen atoms and the aminonitrogen atoms are cis, respectively. Complex 2 is dinuclear of vanadium(V) with dioxobridges. A similar template reaction with copper(II) afforded Cu(salen) (H2salen = N,N'-bis(salicylidene)ethylendiamine) (13) in a low yield.

2

Complexes of Cobalt(II), Nickel(II) and Copper(II) with 3-Hydroxysalicyliden-p-aminoacetophenoneoxime

100%

Tuna S. , Canpolat E. , Kaya M.

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2006

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tom Vol. 80, nr 2

227-234

EN

The complexes of Co(II), Ni(II) and Cu(II) with 3-hydroxysalicyliden-p-aminoacetophenoneoxime were prepared and characterized by physical, spectral and analytical data. The metal:ligand stoichiometric ratio is 1:2 in all the complexes. It was determined that the bidentate behavior of the ligand is accomplished via the phenolic oxygen and the azomethine nitrogen atoms. The presence of water is revealed by thermograms and supported by the presence of relevant bands in their IR spectra. Suitable structures have been proposed for these complexes.

3

Complexes of iron(III) salen and saloph Schiff bases bridges by dicarboxylic acids

80%

Kopel P. , Sindelar Z. , Biler M. , Klicka R.

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tom Vol. 72, nr 9

2060-2066

EN

Six dinuclear Fe(III) complexes involving tetradentate Schiff bases N,N'-bis(salicylidene)ethylenediamine (salenH2) or bis(salicylidene)o-phenylenediamine (salophH2) with 2,6-pyridinedicarboxylic acid (2,6-dicarpyH2), thiodiglycolic acid (tdgaH2) or 3,3'-thiodipropionic acid (3,3'-tdpaH2) have been synthesized and characterized by elemental analysis, IR spectroscopy and conductivity measuremenys. The magnetic behavioral of all complexes has been studied between 77-298 K. The dicarboxylic acids form bridges between paramagmetic centers and weak antiferromagnetic intramolecular exchanges were found. Thus, the complexes can be characterized as high spin distorted octahedral iron(III), except for [{Fe(saloph)}2(2,6-dicarpy)], where S1 = S2 = 3/2 spin-exchange model complies best with experimental data and the iron(III) has probably aquare-pyramidal coordination mode. The HDW S1 = S2 = 5/2 spin-exchange model with (H = -2S1S2) was applied in the case of the other complexes. The antiferromagnetic coupling parameters J vary in the range of -1.06 to -5.87 cm(-1).

4

Mn₂O₃ Nanoparticles Synthesized from Thermal Decomposition of Manganese(II) Schiff Base Complexes

80%

Khalaji A. , Ghorbani M.

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tom 133

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nr 1

7-9

EN

The Mn₂O₃ nanoparticles have been prepared using solid state thermal decomposition of MnL¹ and MnL², L¹=N,N'-bis(2-hydroxy-4-methoxybenzophenone)-1,3-propanediamine and L²=N,N'-bis(2-hydroxy-4-methoxybenzophenone)-1,2-cyclohexanediamine, at 500°C for 3 h and characterized by the Fourier transform infrared spectroscopy, X-ray powder diffraction and scanning electron microscopy. The Fourier transform infrared spectroscopy and X-ray powder diffraction confirm that the formed product at 500°C is Mn₂O₃. The MnL¹ and MnL² complexes were prepared from the one-pot reaction of MnCl₂·H₂O, diamine and 2-hydroxy-4-methoxybenzophenone and characterized by elemental analyses, the Fourier transform infrared spectroscopy and thermogravimetry.

5

Symmetrical and asymmetrical imino-naphthalimides in perovskite solar cells

80%

Korzec M. , Kotowicz S. , Pająk A. K. , Schab-Balcerzak E.

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tom Vol. 29, No. 4

175--180

EN

In perovskite solar cells, series of symmetrical and asymmetrical imino-naphthalimides were tested as hole-transporting materials. The compounds exhibited high thermal stability at the temperature of the beginning of thermal decomposition above 300 °C. Obtained imino-naphthalimides were electrochemically active and their adequate energy levels confirm the application possibility in the perovskite solar cells. Imino-naphthalimides were absorbed with the maximum wavelength in the range from 331 nm to 411 nm and emitted light from the blue spectral region in a chloroform solution. The presented materials were tested in the perovskite solar cells devices with a construction of FTO/b-TiO2/m-TiO2/perovskite/ HTM/Au. For comparison, the reference perovskite cells were also performed (without hole-transporting materials layer). Of all the proposed materials tested as hole-transporting materials, the bis-(imino-naphthalimide) containing in core the triphenylamine structure showed a power conversion efficiency at 1.10% with a short-circuit current at 1.86 mA and an open-circuit voltage at 581 mV.

6

Synthesis, Characterization and Catalytic Activity of the Manganese(III) - Schiff Base Complexes

80%

Szypa M. , Pelech R.

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tom Vol. 82, nr 3

481-486

EN

Symmetrical and un symmetrical mangaese(III) Schiff base complexes of the type [MnClLLc], (LLc = [ONNO] = symmetrical and unsymmetrical Schiff base derivatives of trans-1,2-diaminocyclohexane and 2-hydroxynaphthaldehyde as well as R-salicyl - aldehydes) were synthesized by the reactions of the appropriate Schiff base with Mn(CH3COO)3ź4H2O and lithium chloride. The complexes were characterized by elemental analysis, IR and UV-vis spectrometric methods. The catalytic activity of the prepared complexes was studied in the epoxidation of styrene and cyclohexene.

7

Studies on DNA Cleavage and Antimicrobial Screening of Transition Metal(II) Complexes Derived from Tetradentate Schiff Base

80%

Raman N. , Dhaveethu Raja J. , Sakthivel A.

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tom Vol. 81, nr 12

2059-2067

EN

A new series of transition metal complexes of Cu(II), Ni(II), Co(II), Mn(II), Zn(II), VO(IV), Hg(II) and Cd(II) have been synthesized from the Schiff base (H2L) derived from 4-aminoantipyrine, 3-hydroxy-4-nitrobenzaldehyde and 2-aminophenol. The structural features have been arrived from their elemental analyses, magnetic susceptibility, molar conductance, mass, IR, UV-Vis, 1H NMR and ESR spectral studies. The data show that the complexes have composition of ML type. The UV-Vis, magnetic susceptibility and ESR spectral data of the complexes suggest a square planar geometry around the central metal ion except VO(IV) complex which has square-pyramidal geometry. The redox behavior of copper and vanadyl complexes has been studied by cyclic voltammetry. The minimum inhibitory concentration (MIC) values of the in vestigated compounds indicate that the complexes have higher antimicrobial activity than the free ligand. The nuclease activity of the above metal complexes shows that only copper and nickel complexes cleave DNA through redox chemistry.

8

Synthesis, crystal structures, and fluorescent properties of zinc(II) complexes with benzazino-2-carboxalidin-2-aminophenols

70%

Nosova E. , Stupina T. , Chupakhin A. , Lipunova G. , Valova M. , Slepukhin P. , Charushin V.

Open Chemistry

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2015

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tom 13

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nr 1

EN

Complexes ZnL2 with novel fluorinated benzazines as tridentate ligands (HL = 6,7-difluoroquinoxalinand 6,7-difluoroquinolincarboxalidin-2-aminophenol) have been prepared. The photophisical properties of the ligands and the complexes has been studied.

9

Novel s-Triazinyl Schiff Base/Chalcone Congeners: Rational, Synthesis, Antimicrobial and Anti-TB Evaluation

70%

Lakum H. P. , Shah D. R. , Chikhalia K. H.

International Letters of Chemistry, Physics and Astronomy

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2014

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tom Vol. 19, iss. 1

56--73

EN

The occurrence of Multi Drug Resistant (MDR) infectious microbial strains has been increased upto alarming level which affects the public health worldwide. To cure this problem, a library of s-triazinyl derivatives comprising schiff base or chalcone motif have been rationalized, synthesized and screened for their in vitro antibacterial activity against five bacterial strains (Staphylococcus aureus MTCC 96, Bacillus subtilis MTCC 441, Escherichia coli MTCC 739, Pseudomonas aeruginosa MTCC 741 and Klebsiella pneumoniae MTCC 109) and four fungal strains (Aspergillus niger MTCC 282, Aspergillus fumigates MTCC 343, Aspergillus clavatus MTCC 1323, Candida albicans MTCC 183) using broth dilution technique. All the newly synthesized scaffolds were further evaluated for their in vitro anti-TB efficacy against the tubercular strain (Mycobacterium tuberculosis H37Rv) using Lowenstein-Jensen MIC method. All the derivatives were well characterized by IR, 1H NMR, 13C NMR, elemental analysis as well as mass spectroscopy.

10

Z badań nad spektroskopią UV-VIS kompleksów metali przejściowych z zasadami Schiffa w roztworach

70%

Kurzak K. , Kuźniarska-Biernacka I.

Wiadomości Chemiczne

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2001

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tom [Z] 55, 9-10

913--931

EN

Metal complexes derived from Schiff bases have been known for one hundred years. The complexes have occupied a central role in the development of coordination chemistry. This situation is manifested by huge number of publications ranging from the physicochemical to biochemical relevant studies of these complexes. The reason for this sustained interest in those compounds are undoubtedly many but important among them must be their general ease to preparation, and diverse properties, e.g., their ability to reversibly bind oxygen, catalytic activity, photochromic and thermochromic properties. Schiff base are those compound containing the azomethine group (-RHC=N-) and usually formed by the condensation of amine with carbonyl compound. Bases which are effective as coordinating ligands bear a functional group, usually -OH, sufficiently near the site of condensation that a five- or six membered chelate ring can be formed upon reaction with a metal ion. Tautomeric equilibrium of three tautomers is possible for Schiff base compounds: imine, enamine and keto-imine. The presence of the imine and enamine tautomeric forms depends on the formation of intramolecular hydrogen bond. It is claimed that enamine form is dominant in napthaldimines while imine form in salicylaldimines. The distribution of the tautomeric equilibrium is strongly depend on the solvents. The presence of keto-imine form is insignificant for Schiff base compounds, but is found in the case of b-diketones and arylimines of b-ketoethers. The most significant complexes of the salicylaldimines are of the types: bi-, tri- and tetracoordinateSchemat 3. The geometry of Schiff base complexes depends on substituent at the coordinating nitrogen atoms. For tetra-coordinate copper(II) complexes different types of geometry is possible. A planar structure has been established for the copper(II) complexes (with bidentate Schiff base) where the substituent is hydrogen atom, hydroxyl, methyl, n-butyl or n-amyl group. In the other hand the copper(II) complexes where the substituent is isopropyl or tert-butyl are pseudo-tetrahedral. For tetra-coordinate cobalt(II), either a square-planar or pseudo-tetrahedral geometry is possible. A pseudo-tetrahedral structure has been established for the cobalt(II) complexes (with bidentate Schiff base) where the substituent is n-propyl, isopropyl, n-butyl, tert-butyl, cyclohexyl or aryl group. Cobalt(II) complexes with bidentate Schiff bases where the substituent is hydrogen atom or hydroxyl group have a planar geometry, because of formation hydrogen bonding between hydrogen (from hydroxyl group) and oxygen (from aldehyde linkage). Geometry of this type is characteristic for cobalt(II) complexes witch Schiff base tetradentate (e.g., with salicylidene-ethylenediamine). The aim of this account is to summarize the result of studies of structural and spectroscopic properties on Schiff bases and their complexes. These have been reviewed based on 104 articles.

11

Synthesis, Spectral, Redox and Biological Screening Studies of Schiff Base Copper(II), Nickel(II), Cobalt(II), Oxovanadium(II) and Zinc(II) Complexes Derived from Curcumin and 4-Aminoantipyrine

70%

Kulandaisamy A. , Thomas M.

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tom Vol. 82, nr 3

469-480

EN

Neutral complexes of Cu(II), Ni(II), Co(II), VO(II) and Zn(II) have been synthesized from the new Schiff base de rived from curcumin and 4-aminoantipyrine. The structural features of the com plexes have been de ter mined from their microanalytical, magnetic susceptibility, molar conductance, IR, UV-Vis, 1H-NMR, mass and ESR spectral data. All the complexes exhibit square planar geometry while vanadyl complex exists in a square pyramidal geome try. Their magnetic susceptibility measurements and low conductance data provideevidence for the monomeric and non-electrolytic nature of the complexes respectively. Mass, 1H-NMR spectra of the Schiff base and its com plexes suggest that the general formula of the complexes is [ML2]. The redox behaviour of the Cu(II), Ni(II) and VO(II) complexes in MeCN at 300 K was studied by using cyclic voltammetry. The X-band ESR spectra of copper and vanadyl complexes in DMSO solution at 300 K and 77 K were recorded and their salient features were discussed. The antimicrobial activity of the ligand and its complexes against the bacteria Staphylococus aureus, Bacillus subtilis, Klebsiella pneumoniae, Salm nella typhi, Pseud monas aeruginosa and Shigella flexneri are also reported.

12

Cu(II), Co(II), Ni(II), Mn(II) and Zn(II) Schiff base complexes of 3-hydroxy-4-[N-(2-hydroxynaphthylidene)-amino]-naphthalene-1-sulfonic acid: Synthesis, Spectroscopic, thermal, and antimicrobial studies

60%

Bakare S. B.

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tom Vol. 21, nr 3

26--34

EN

Five divalent transition metals Cu(II), Co(II), Ni(II), Mn(II) and Zn(II) complexes have been synthesized using 3-hydroxy-4-[N-(2-hydroxynaphthylidene)-amino]-naphthalene-1-sulfonic acid (H3L) Schiff base as a ligand derived from the condensation reaction between 4-amino-3-hydroxynaphthalene-1-sulfonic acid and 2-hydroxy-1-naphthalde-hyde. The synthesized complexes were characterized using microanalytical, conductivity, FTIR, electronic, magnetic, ESR, thermal, and SEM studies. The microanalytical values revealed that the metal-to-ligand stoichiometry is 1:1 with molecular formula [M2+(NaL)(H2O)x].nH2O (where x = 3 for all metal ions except of Zn(II) equal x = 1; n = 4, 10, 7, 4, and 6 for Cu(II), Co(II), Ni(II), Mn(II) and Zn(II), respectively). The molar conductivity result indicates that all these complexes are neutral in nature with non-electrolytic behavior. Dependently on the magnetic, electronic, and ESR spectral data, octahedral geometry is proposed for all the complexes except to zinc(II) complex is tetrahedral. Thermal assignments of the synthesized complexes indicates the coordinated and lattice water molecules are present in the complexes. SEM micrographs of the synthesized complexes have a different surface morphologies. The antimicrobial activity data show that metal complexes are more potent than the parent ligand.

13

Styrene oxidation by copper(II) complexes salen-type encapsulated into NaY zeolite

60%

Kuźniarska-Biernacka I. , Carvalho M. A. , Correia Neves I. , Fonseca A. M. , Lisińska-Czekaj A. , Czekaj D.

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tom Vol. 58, iss. 4

1291--1294

EN

The copper(II) complex with a Schiff-base salen-type ligand has been encapsulated in the nanopores of a NaY zeolite by using two different methodologies, the flexible ligand and in situ complex preparation methods. The encapsulated and non-encapsulated copper(II) complexes were screened as catalysts for styrene oxidation by using TBHP as the oxygen source in acetonitrile solvent. Under the optimized conditions, the catalysts exhibited moderate activity with higher selectivity to benzaldehyde. Both heterogeneous catalysts were found to be reusable after the catalytic cycle, but with some loss of activity.

PL

Osadzenie kompleksu miedzi(II) z zasadą Schiffa typu salen na zeolicie typu NaY zostało przepowadzone za pomocą dwóch metod „flexible ligand" i „in situ”. Katalityczne właściwości otrzymanego kompleksu oraz jego heterogenizowanych analogów badano w reakcji utleniania styrenu w obecności TBHP. Jako rozpuszczalnik stosowano acetonitryl. Testowane katalizatory wykazują średnią aktywność katalityczną z tendencją wytwarzania aldehy du benzoesowego. Oba heterogenizowane katalizatory mogą być wykorzystywane ponownie bez utraty aktywności katalitycznych.

14

Novel N,N’-bis(2,4-dimethoxybenzylidene)ethylenediamine PVC membrane electrode for the potentiometric iron selective sensor based on Schiff base ligand

51%

Kumar S. , Sandhu S. K. , Patel A. K. , Parmar K. H.

Polimery

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2022

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tom Vol. 67, nr 5

197--204

EN

N,N’-bis(2,4-dimethoxybenzylidene)ethylenediamine was synthesized and used as a membrane carrier to create a novel poly(vinyl chloride) membrane potentiometric sensor that is selective especially for Fe3+ ions. The super-Nernstian slope of the projected sensor was 19.5 mV per decade over a concentration range of 7.3•10-8–1•10-1 M having detection limit at 7.3•10-8 M. The sensor displayed a linear potential response for the detection of Fe3+ ions in about 30 seconds, and it had a lifespan of no less than 9 weeks without lacking any potential divergence. The selected sensor showed high selectivity in water solutions in relation to Fe3+ ions, even in the presence of other metal cations in the pH range of 3.6–10.

PL

Przedmiotem badań był potencjometryczny czujnik do selektywnego oznaczania jonów Fe3+ oparty na membranie wykonanej z poli(chlorku winylu) i N,N’-bis(2,4-dimetoksybenzylideno)etylenodiaminy. Nachylenie super-nernstowskie (ang. super-Nernstian slop) badanego czujnika wynosiło 9,5 mV na dekadę w zakresie stężeń 7,3•10-8–1•10-1 M z limitem detekcji 7.3•10-8 M. Czujnik wykazywał w obecności jonów Fe3+ liniową odpowiedź przez około 30 s, a jego czas życia bez rozbieżności potencjałów wynosił nie mniej niż 9 tygodni. Wybrany czujnik wykazywał w roztworach wodnych wysoką selektywność w stosunku do jonów Fe3+ nawet w obecności innych kationów metali w zakresie pH 3,6–10.

15

Thermal and long period stability of series of V(V), V(IV) and V(III) complex with Schiff base ligands in solid state

41%

Szklarzewicz J. , Jurowska A. , Hodorowicz M. , Gryboś R.

Science, Technology and Innovation

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2019

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tom Vol. 4, no. 1

30--36

EN

The synthesis and physicochemical properties of three new complexes of vanadium at +5, +4 and +3 oxidation state are described and discussed. The octahedral surrounding of vanadium for V(III) complexes of [V(L1)(HL1)] general formula is filled with two ONO tridentate ligand L, for V(IV) one ONO ligand L, oxido ligand and 1,10-phenanthroline (phen) as a co-ligand are presented in complexes of [VO(L2)(phen)]. For V(V) the complexes of [VO2(L1)(solv)] type were formed. As ligands, the H2L Schiff bases were formed in reaction between 5-hydroxysalcylaldehyde and phenylacetic hydrazide (H2L1) and 3,5- dichlorosalicyaldehyde and 4-hydroxybenzhydrazide (L2). The magnetic moment measurements, in 8 year period, show, that V(III) complexes slowly oxidise to V(IV) with preservation of the nonoxido character of the complexes, while V(IV) complexes were found to be stable. The TG and SDTA measurements indicate, that thermal stability depends mainly on the oxidation state of vanadium. The less thermally stable are the V(V) complexes, while V(IV) and V(III) are stable up to ca. 200oC. In solution, at pH 2 (similar to that in human digestion system), again the V(IV) are the most stable, only at pH 7.0 V(III) complexes had higher stability. The most stable, thus best for pharmaceutical use, are V(IV) complexes.

16

Zastosowanie metod dynamiki molekularnej w badaniach nad układami z wiązaniami wodorowymi

36%

Jezierska A. , Panek J. J.

Wiadomości Chemiczne

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2017

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tom [Z] 71, 7-8

473--495

EN

Modern computational chemistry offers a wide variety of methods allowing us to investigate very complex systems. In the current study, we would like to focus on ab initio and classical molecular dynamics to show their applications in our research. Car-Parrinello molecular dynamics (CPMD) was carried out to study compounds possessing intra- and intermolecular hydrogen bonds. Our simulations were performed in vacuum, in solvent and in crystalline phase. It is well known that intramolecular hydrogen bonding stabilizes 3D structure of molecules. The strength of the bonding and its features are influenced by inductive and steric effects. Our short overview on CPMD application to systems with intramolecular HB we start from Schiff and Mannich bases -model compounds to investigate intramolecular hydrogen bonding. Other examples reported here derive from the class of N-oxide type compounds. Special attention was devoted to another representative structure in such investigations – picolinic acid N-oxide. In some examples listed above proton transfer phenomena occurred making these compounds interesting objects for future excited state studies. Aliphatic boronic acid was used as a model example to study intermolecular hydrogen bonds based on CPMD method. Further, classical molecular dynamics was applied to investigate proteins. Here, we would like to report our results for two biomolecules. The first one is proteinase K for which the impact of mercury(II) on its catalytic center was studied. The second one is streptavidin. For the latter one its complexes with biotinylated ligands were investigated. We close our review with a paragraph describing further development and perspectives related to CPMD method.

17

Właściwości spektralne i fotofizyczne wybranych cząsteczek aromatycznych i indywiduów przejściowych w krótkożyjących stanach wzbudzonych

36%

Maciejewski A. , Burdziński G. , Dobek K. , Grabowska A. , Karolczak J. , Krystkowiak E. , Kubicki J. , Łukaszewicz A. , Naskręcki R. , Ziołek M.

Wiadomości Chemiczne

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2007

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tom [Z] 61, 3-4

137-165

EN

The paper presents results of spectral and photophysical studies obtained for molecules representing three different classes of compounds: • Schiff bases with strong intramolecular hydrogen bond, occurring in a few phototautomers, • Aminophtalimides with LE and ICT type electronic excited states forming exciplexes through hydrogen bonds with the solvent molecules, • Thioketones with a thiocarbonyl group becoming exceptionally reactive in the S2 state, quenched by molecules of solvent of different properties. It should be emphasized that for all compounds, irrespective of the complex mechanisms of their deactivation characterised by different dynamics, the dominant final process is the reproduction of the chemically unchanged substrate in the ground state. The necessary condition of the correct interpretation of the complex properties of the compounds studied in electronic excited states is the proper choice of solvents of specific properties. Through this proper choice of solvents it becomes possible to study the role of nonspecific and specific (hydrogen bonds) interactions with the solvent and to observe the intramolecular and intermolecular processes of deactivation. The results presented could be obtained thanks to the use of the steady-state and time-resolved laser methods of absorption and emission spectroscopy with a pico- and femtosecond resolution. The results obtained can be helpful in the study of compounds of similar properties and more complex systems including biological systems.