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Gytis-Kazimieras Kupetis Gintautas ?aduikis Ona Nivinskien? Olegas Eicher-Lorka 《Monatshefte für Chemie / Chemical Monthly》2002,71(11):313-321
A series of 1-alkyl-4-dialkylaminopyridinium halides derived from 4-dimethylamino- and 4-morpholinopyridines were synthesized and tested as phase-transfer catalysts in three typical reactions of dichlorocarbene: dehydration of benzamide, N-formylation of diphenylamine, and dichlorocyclopropanation of styrene. The catalytic performance of the above compounds was found comparable or higher than that of conventional quaternary ammonium catalysts. The influence of catalyst structure on the reactivity was evaluated. 相似文献
2.
Algirdas Matijoška Tatjana Charkova Zenonas Kuodis Vladislava Voiciuk Olegas Eicher-Lorka 《Central European Journal of Chemistry》2012,10(1):113-120
The synthesis of a new halogenide containing hexyltriethylene glycol chain functionalized with biotin is reported. The general
possibility of this linker to use as the building block for biotinylated compounds syntheses is demonstrated. Two biotinylated
esters with different properties for useful surface modification and as fluorescence probes for proteins marking were synthesized.
The properties of mentioned compounds were investigated by using surface plazmon resonance ellypsometry and fluorescence spectroscopy. 相似文献
3.
Mažeikienė R Niaura G Eicher-Lorka O Malinauskas A 《Journal of colloid and interface science》2011,357(1):189-197
Surface-enhanced Raman spectroscopy (SERS) was used to probe the structure of adsorbed and electropolymerized Meldola blue (MB) films on roughened gold surfaces in solutions with pH 1.0 and 7.0 by using 785 nm excitation wavelength. Spectral bands were assigned based on density functional theory (DFT) calculations at B3LYP/6-311+G(2d, p) level. The most characteristic band of the oxidized MB form was found to be the breathing vibration of the central ring containing heteroatoms at 596 cm(-1). Based on a red shift of bands assigned to vibrations of double C=N(C(2)H(6)) bonds and adjacent ring C=C bonds in surface spectra as compared with solution 1 it was suggested that polymerization and interaction with an electrode surface proceed through these moieties. The presence of out-of-plane bands in SERS spectra was attributed to "flat" or slightly "tilted" orientation of aromatic rings at the interface. Potential-dependent spectral changes were followed by SERS spectroscopy. Raman spectra of the reduced MB form were obtained in both pH 1.0 and pH 7.0 solutions by analysis of the potential-difference SERS spectra. Reduced MB form can be recognized by characteristic bands near 1620, 1574, 1374, and 1234 cm(-1). By comparing the intensities of 1637 cm(-1) (oxidized MB form) and 1374 cm(-1) (reduced MB form) bands in experimental spectra of polymerized MB in pH 1.0 solution, a reduction-induced decrease by factor of 7 was estimated. A similar tendency in intensity changes showed calculations indicating that this effect is associated with reduction-induced changes in the molecular structure of the dye. 相似文献
4.
Zenonas Kuodis Ieva Matulaitien Marija pandyreva Linas Labanauskas Sigitas Ston
ius Olegas Eicher-Lorka Rita Sadzevi
ien Gediminas Niaura 《Molecules (Basel, Switzerland)》2020,25(23)
Multifunctional amide-containing self-assembled monolayers (SAMs) provide prospects for the construction of interfaces with required physicochemical properties and distinctive stability. In this study, we report the synthesis of amide-containing thiols with terminal phenylalanine (Phe) ring functionality (HS(CH2)7CONH(CH2)2C6H5) and the characterization of the formation of SAMs from these thiols on gold by reflection absorption infrared spectroscopy (RAIRS). For reliable assignments of vibrational bands, ring deuterated analogs were synthesized and studied as well. Adsorption time induced changes in Amide-II band frequency and relative intensity of Amide-II/Amide-I bands revealed two-state sigmoidal form dependence with a transition inflection points at 2.2 ± 0.5 and 4.7 ± 0.5 min, respectively. The transition from initial (disordered) to final (hydrogen-bonded, ordered) structure resulted in increased Amide-II frequency from 1548 to 1557 cm−1, which is diagnostic for a strongly hydrogen-bonded amide network in trans conformation. However, the lateral interactions between the alkyl chains were found to be somewhat reduced when compared with well-ordered alkane thiol monolayers. 相似文献
5.
Riauba L Niaura G Eicher-Lorka O Butkus E 《The journal of physical chemistry. A》2006,110(50):13394-13404
Different cysteamine (H2N-CH2-CH2-SH) ionization forms have been studied by polarized Raman spectroscopy in solutions prepared with H2O and D2O and by DFT calculations at the B3LYP/6-31++G(d,p) level. To account for solvation effects, we employed the integral equation formalism polarizable continuum model (IEFPCM) option and explicit water molecules. Calculated relative energies and Raman spectra revealed that gauche rotamers around the C-C bond are the most stable conformers in solution. The experimental pKa values and Raman spectra of various ionization forms were best predicted by using a model with three explicit water molecules and the IEFPCM option. In general, the use of IEFPCM tends to lower the calculated frequencies for a few bands, but in some cases (S-H stretching mode) this effect is expressed very strongly. Potential energy distribution (PED) analysis of gauche conformers of various cysteamine ionization forms provided the possibility of discriminating spectroscopically methylene groups adjacent to sulfur, (CH2)S, and nitrogen, (CH2)N, sites. In general, stretching and scissoring modes as well as wagging and twisting vibrations of the (CH2)N group were found to be at higher frequencies. The influence of ionization of SH and NH2 groups on the vibrational spectrum is discussed, and Raman markers for further amine group ionization studies are suggested. 相似文献
6.
Milda M. Burbuliene Olegas Bobrovas Povilas Vainilavicius 《Journal of heterocyclic chemistry》2006,43(1):43-47
7.
Zenonas Kuodis Albertas Rutavičius Algirdas Matijoška Olegas Eicher-Lorka 《Central European Journal of Chemistry》2007,5(4):996-1006
New hydrazones of 2-(5-thioxo-4,5-dihydro-1,3,4-thiadiazol-2-ylthio)acetohydrazide have been obtained and the percentages
of anti/syn - conformers were determined. Based on the analyses of 1H NMR spectra, it was concluded that for hydrazones obtained from the 2- hydroxybenzaldehydes and 2’-hydroxycetophenones the
ratio between the anti-and syn-conformers depends on the strength of intramolecular hydrogen bond (IMHB) between the nitrogen atom of the imino group and
the proton of the 2-hydroxy group. It was shown that increase in IMHB strength results in stabilization of the anti-conformer in solution.
相似文献
8.
Gytis-Kazimieras Kupetis Gintautas Šaduikis Ona Nivinskienė Olegas Eicher-Lorka 《Monatshefte für Chemie / Chemical Monthly》2002,133(3):313-321
Summary. A series of 1-alkyl-4-dialkylaminopyridinium halides derived from 4-dimethylamino- and 4-morpholinopyridines were synthesized
and tested as phase-transfer catalysts in three typical reactions of dichlorocarbene: dehydration of benzamide, N-formylation
of diphenylamine, and dichlorocyclopropanation of styrene. The catalytic performance of the above compounds was found comparable
or higher than that of conventional quaternary ammonium catalysts. The influence of catalyst structure on the reactivity was
evaluated.
Received June 27, 2001. Accepted (revised) September 25, 2001 相似文献
9.
Misiūnas A Niaura G Talaikyte Z Eicher-Lorka O Razumas V 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2005,62(4-5):945-957
Hydrogen bonding and interchain interactions in phytantriol, 3,7,11,15-tetramethyl-1,2,3-hexadecanetriol, have been studied by Fourier transform infrared (FT-IR) and Raman spectroscopies. Assignments of the bands were performed based on the OH/OD isotopic substitution, molecular modeling, and measurements of polarized Raman spectra. Marker bands were evaluated from the temperature-dependent spectral changes. It is shown that Raman spectroscopy provides sensitive markers, namely I(delta(CH2))/I(deltas(CH3)), tau(CH)2, I(nus(CH3)(FR))/I(nus(CH2)), and nus(CH2) for probing the interactions between the hydrocarbon chains. Hydrogen bonding interaction might be studied through the difference Raman spectroscopy by the analysis of polarized band at 811 cm-1. Relationship is found between the frequencies of IR bands at 883-873 and 1097-1086 cm-1, associated with the vibrations localized at the primary COH site, and the frequencies of OH stretching mode, making these bands specific markers in the analysis of hydrogen bonding. Evaluated marker bands may be of utility to probe the interchain and hydrogen bonding interaction of phytantriol with guest molecules in the practically important aqueous liquid-crystalline phases of this lipid. 相似文献
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