- Spectroscopic, semi-empirical and antimicrobial studies of a new amide of monensin A with 4-aminobenzo-15-crown-5 and its complexes with Na+ cation at 1:1 and 1:2 ratios
-
A new amide of monensin A with 4-aminobenzo-15-crown-5 (M-AM3) was synthesised and its ability to form complexes with Na+ cations was studied by ESIMS, 1H, 13C and 23Na NMR, FTIR and PM5 semi-empirical methods. ESI mass spectrometry indicates that in the gas phase M-AM3 amide forms complexes of 1:1 and 1:2 stoichiometry with Na + cations. The formation of such complexes is also confirmed in the acetonitrile solution, in which the existence of equilibrium between two structures A and B is found, of which B structure is dominant. The structures of M-AM3 and its 1:1 and 1:2 complexes with Na+ cations are stabilised by various intramolecular hydrogen bonds, which are discussed in detail. The in vitro biological tests have demonstrated that the new M-AM3 amide shows good activity towards some strains of Gram-positive bacteria (MIC 25-50 μg/ml).
- ?owicki, Daniel,Huczyński, Adam,Stefańska, Joanna,Brzezinski, Bogumil
-
-
Read Online
- Can temperature be used to tune the selectivity of membrane ion-selective electrodes?
-
The selectivity coefficients, KIJpot, of ion-selective electrodes (ISEs) have been fundamentally related to thermodynamic parameters, but yet, the effect of temperature on KIJpot has not been studied. We describe a new approach to fine-tune the selectivity of ISEs based on the effect of temperature on selectivity coefficients. This effect was quantified for ion exchangers as well as neutral carrier ionophores. Potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate was used as an ion exchanger in a poly(vinyl chloride) membrane. The corresponding electrode showed an inverse relationship between log KNapot+,K+ and temperature. Additionally, sodium-selective electrodes using monensin, monensin methyl ester (MME), and monensin decyl ester (MDE) were evaluated as models of electrodes based on neutral carriers. The electrode based on monensin showed an enhancement in the selectivity for sodium over potassium by half an order of magnitude as the temperature increased from 20 to 50 °C, while the electrodes based on MME or MDE showed a very small change in selectivity. This can be explained in light of changes in the formation constants between the ions and ionophores with temperature. The theory of the effect of temperature on selectivity for both ion exchangers and neutral carrier ionophores is also discussed.
- Zahran, Elsayed M.,Gavalas, Vasileios,Valiente, Manuel,Bachas, Leonidas G.
-
-
Read Online
- 1H, 13C NMR, FT-IR, ESI MS and PM5 studies of a new 3,6,9-trioxadecylamide of monensin A and its complexes with Li+, Na+ and K+ cations
-
A new 3,6,9-trioxadecylamide of monensin A (M-AM4) has been synthesised and its ability to form complexes with Li+, Na+ and K + cations has been studied by ESI mass spectrometry, 1H and 13C NMR, FT-IR spectroscopy and PM5 semiempirical method. The ESI MS data indicate that M-AM4 forms complexes with Li+, Na+ and K+ of exclusively 1:1 stoichiometry which are stable up to cv = 70 V. The formation of the M-AM4-Na+ is strongly favoured. Above cv = 70 the fragmentation process is observed. The spectroscopic studies show that the structures of the M-AM4 and its complexes with the cations of 1:1 stoichiometry are stabilized by intramolecular hydrogen bonds in which the OH groups are always involved. The CO amide group is engaged in the complexation process of each cation. The M-AM4-K+ complex can also assume a structure in which the CO amide group does not participate in the complexation but the complexes of such structure do not dominate.
- ?owicki, Daniel,Huczyński, Adam,Brzezinski, Bogumil,Bartl, Franz
-
experimental part
p. 121 - 131
(2011/04/23)
-
- Structural and antimicrobial studies of a new N-phenylamide of monensin A complex with sodium chloride
-
A complex between a new N-phenylamide of monensin A (M-AM1) and sodium chloride has been synthesised and studied by X-ray diffraction and FT-IR spectroscopy. The crystal structure of the complex between M-AM1 and sodium chloride with acetonitrile was exam
- ?owicki, Daniel,Huczyński, Adam,Ratajczak-Sitarz, Ma?gorzata,Katrusiak, Andrzej,Stefańska, Joanna,Brzezinski, Bogumil,Bartl, Franz
-
experimental part
p. 53 - 59
(2009/09/30)
-
- Spectroscopic, mass spectrometry, and semiempirical investigations of a new 2-(2-methoxyethoxy)ethyl ester of Monensin A and its complexes with monovalent cations
-
A new 2-(2-methoxyethoxy)ethyl ester of Monensin A (MON7) has been synthesized and its capability of complex formation with Li+, Na+, and K+ cations has been studied by ESI MS, 1H and 13C NMR, FT-IR, and PM5 semiempirical methods. ESI mass spectrometry indicates that MON7 forms complexes with Li+, Na+, and K+ of exclusively 1:1 stoichiometry which are stable up to cv = 70 V. The formation of complexes between MON7 and Na+ cations is strongly favored. Starting from about cv = 90 V fragmentation of the respective complexes is observed, primarily characterized by several dehydration steps. The structures of the MON7 complexes with Li+, Na+, and K+ cations are stabilized by intramolecular hydrogen bonds in which the OH groups are always involved. The structures are visualized and discussed in detail. It has been proved that the formation of a pseudo crown ring structure formed by MON7 is preferred in complexes with Na+ cations.
- Huczyński, Adam,?owicki, Daniel,Brzezinski, Bogumil,Bartl, Franz
-
-
