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Tytuł:
Analysis of Common Explosives in Different Solvents by Nuclear Magnetic Resonance Spectroscopy
Autorzy:
Szala, M.
Szymańczyk, L.
Powiązania:
https://bibliotekanauki.pl/articles/358931.pdf
Data publikacji:
2014
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
NMR spectroscopy
common explosives
detection
Opis:
The results of systematic multinuclear NMR studies of 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), 1,3,5,7-tetranitro-1,3,5, 7-tetraazacyclooctane (HMX) and 3-nitro-1,2,4-triazol-5-one (NTO) are presented. For comparison of interactions between the analytes and the solvents, experiments in both deuterated DMSO and CDCl3 (where possible) were performed. Complete assignment of the resonance signals for the compounds investigated are presented. Analysis of the high resolution NTO spectra leads to new conclusions about the different reactivities of the N-H protons. The results can be used for many analytical purposes, such as solvent matching for extracting traces of explosives, controlling the purity of various samples etc.
Źródło:
Central European Journal of Energetic Materials; 2014, 11, 1; 129-142
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Solution structure of conformationally restricted vasopressin analogues.
Autorzy:
Trzepałka, Emilia
Oleszczuk, Marta
Maciejczyk, Maciej
Lammek, Bernard
Powiązania:
https://bibliotekanauki.pl/articles/1043316.pdf
Data publikacji:
2004
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
vasopressin
X-PLOR
NMR spectroscopy
EDMC
peptide conformation
Opis:
In recent years, a massive effort has been directed towards designing potent and selective antagonists of neurohypophyseal hormones substituted at position 3. Modification of vasopressin at position 3 with 4,4'-biphenylalanine results in pharmacologically inactive analogues. Chemically, this substitution appears to vary only slightly from those previously made by us (1-Nal or 2-Nal), which afforded potent agonists of V2 receptors. In this situation, it seemed worthwhile to study the structure of the analogues with 4,4'-biphenylalanine (BPhe) at position 3 in aqueous solution using NMR spectroscopy and total conformational analysis. This contribution is part of extensive studies aimed at understanding spatial structures of 3-substituted [Arg8]vasopressin analogues of different pharmacological properties. NMR data were used to calculate 3D structures for all the analogues using two methods, EDMC with the ECEPP/3 force field, and molecular dynamic with the simulated annealing (SA) algorithm. The structures obtained by the first method show a better fit between the NMR spectral evidence and the calculation for all the peptides.
Źródło:
Acta Biochimica Polonica; 2004, 51, 1; 33-49
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Fluorescence, 1H NMR spectroscopy and molecular dynamics study of the influence of rotamer population on fluorescence decay of tyrosine, phenylalanine and their derivatives
Autorzy:
Ganzynkowicz, R.
Liwo, A.
Wiczk, W.
Powiązania:
https://bibliotekanauki.pl/articles/1965825.pdf
Data publikacji:
2001
Wydawca:
Politechnika Gdańska
Tematy:
tyrosine
phenylalanine
rotamers
fluorescence
molecular dynamics
NMR spectroscopy
Opis:
Molecular dynamics simulations were carried out on tyrosine and phenylalanine and their derivatives with various terminal groups to determine the populations of side-chain rotamers. The obtained populations were compared with those calculated from fluorescence-decay lifetime distributions and NMR studies. It was found that theoretically calculated populations do not match the experimental ones, which suggests that the static rotamer model is inadequate to explain the dynamics of tyrosine and phenylalanine side chain in fluorescence and NMR experiments.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2001, 5, 3; 311-316
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Degradation analysis of radiosensitizer control release system based on the NMR spectroscopy
Autorzy:
Buszman, A.
Kasperczyk, J.
Jaworska, J.
Powiązania:
https://bibliotekanauki.pl/articles/284117.pdf
Data publikacji:
2012
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
Tematy:
biodegradable polyesters
NMR spectroscopy
hydrolytic degradation
polymeric chain microstructure
Opis:
The degradation process of multilayer radiosensitizer releasing systems was conducted and examined via the nuclear magnetic resonance spectroscopy. Copolymers of glycolide and lactide with different chain microstructure were used as biocompatible drug carriers. Metronidazole was used as radiosensitizer. The changes of copolymers chain microstructure were monitored during 16 weeks of hydrolytic degradation of material in artificial Cerebro-spinal Fluid Solution. This study shows distinct differences in the rate of copolymer degradation and changes of the degree of randomness, directly connected with the type of comonomers and the comonomeric molar ratio. During 16 weeks of hydrolytic degradation, copolymers with L-lactidyl units remain resistant to hydrolysis while materials with D,L-lactidyl units are completely degraded. Examined materials can be used as carriers of agents for different types of short-, mid- and long-term therapies based on control release systems.
Źródło:
Engineering of Biomaterials; 2012, 15, 113; 16-18
1429-7248
Pojawia się w:
Engineering of Biomaterials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
2-Tetrazene Derivatives as New Energetic Materials; Synthesis, Characterization and Energetic Properties
Autorzy:
Miró Sabaté, C.
Delalu, H.
Powiązania:
https://bibliotekanauki.pl/articles/358238.pdf
Data publikacji:
2014
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
2-tetrazene
energetic materials
X-ray diffraction
NMR spectroscopy
Opis:
The oxidation of 1,1-dimethylhydrazine with aqueous monochloramine yielded (E)-1,1,4,4-tetramethyl-2-tetrazene (1) as a pale yellow liquid with hypergolic properties. 1 can be oxidized with potassium permanganate to form (E)-1-formyl-1,4,4-trimethyl-2-tetrazene (2) and (E)-1,4-diformyl-1,4dimethyl-2-tetrazene (3). Additionally, 1 reacts with a diethyl ether solution of monochloramine to form a stable 1,1,4,4-tetramethyl-2-tetrazenium chloride salt (4). The chloride in salt 4 was exchanged with various energetic anions, such as nitrate (5), perchlorate (6), 5,5´-azobistetrazolate (7*6H2O), picrate (8) and azide (9). All materials were characterized by analytical and spectroscopic methods and the solid state structures of compounds 2-8 were elucidated. Due to the energetic nature of these materials, they were submitted to friction and impact sensitivity tests and DSC analysis was used to assess their thermal stabilities. Furthermore, the heats of formation of compounds 2-8 were computed using quantum mechanical methods (CBS-4M) and their detonation parameters (pressure and velocity) and specific impulses were also calculated. Lastly, the 2-tetrazene derivatives presented here are of potential interest either as building blocks or as a new class of low toxicity, low sensitivity energetic materials.
Źródło:
Central European Journal of Energetic Materials; 2014, 11, 4; 515-537
1733-7178
Pojawia się w:
Central European Journal of Energetic Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badania strukturalne cyklicznych β-aminoketonów z wykorzystaniem metod obliczeniowych i analizy NMR
Structural studies of cyclic β-amino ketons using computational and NMR methods
Autorzy:
Sidorowicz, K.
Łaźny, R.
Powiązania:
https://bibliotekanauki.pl/articles/142626.pdf
Data publikacji:
2015
Wydawca:
Stowarzyszenie Inżynierów i Techników Przemysłu Chemicznego. Zakład Wydawniczy CHEMPRESS-SITPChem
Tematy:
alkaloidy
konformacje
teoria funkcjonału gęstości
spektroskopia NMR
alkaloids
conformations
density functional theory
NMR spectroscopy
Opis:
Przestrzenna konfiguracja na atomie azotu w cyklicznych β-aminoketonach powoduje, że związki te mogą występować w dwóch stereoizomerycznych formach, w których podstawniki na tym atomie mogą przyjmować orientację aksjalną lub ekwatorialną w stosunku do pierścienia piperydonu. Stereochemia N-podstawionych bicyklicznych β-aminoketonów była badana za pomocą metod eksperymentalnych i teoretycznych, m.in.: spektroskopia NMR, spektroskopii mikrofalowa, rentgenografii strukturalnej i obliczeń DFT.
Because of pyramidal configuration of the nitrogen atom, tropanes, granatanes, and their derivatives can exist in two stereoisomeric forms, in which N-substituents can be oriented axial or equatorial with respect to the piperidone ring. The N-invertomer stereochemistry of N-substituted bicyclic β-amino ketones has been investigated using experimental, and theoretical methods, such as NMR, microwave spectroscopy, crystallography, and DFT calculations.
Źródło:
Chemik; 2015, 69, 7; 401-410
0009-2886
Pojawia się w:
Chemik
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Conformational studies of tachykinin peptides using NMR spectroscopy
Autorzy:
Rodziewicz, S.
Xiao-Fei, Qi.
Rolka, K.
Powiązania:
https://bibliotekanauki.pl/articles/1954059.pdf
Data publikacji:
1998
Wydawca:
Politechnika Gdańska
Tematy:
conformational analysis
tachykinin peptides
NMR spectroscopy
Scyliorhinin II
molecular dynamics calculation methods
DMSO
Opis:
Conformational analysis of two tachykinin family peptides: Scyliorhinin I (ScyI) and Scyliorhinin II (ScyII) was carried out by 1D- and 2D-NMR (DQF-COSY, TOCSY, HMQC, HMBC, NOESY and ROESY) and molecular dynamics calculation methods in water and DMSO. Scyliorhinin I is an equipotent agonist of NK-1 and NK-2 tachykinin receptors and Scyliorhinin II is a selective agonist of the NK-3 tachykinin receptor. In DMSO, two groups of conformations (major and minor) were obtained for both peptides based on the experimental data. The conformations proposed for ScyI represent a folded structure, which show certain similarities to the structures reported for other NK-1 and NK-2 tachykinin agonists. In water ScyII displays a flexible, extended structure, whereas in DMSO the structure is more compact and in the fragment from the centre to the C-terminus several beta -turns may be present.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 1998, 2, 1; 47-53
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zastosowanie spektroskopii NMR do identyfikacji i ilościowych oznaczeń wybranych środków powierzchniowo czynnych
Autorzy:
Siergiejczyk, L.
Powiązania:
https://bibliotekanauki.pl/articles/274283.pdf
Data publikacji:
2011
Wydawca:
Roble
Tematy:
spektroskopia NMR
spektroskopia magnetycznego rezonansu jądrowego
surfaktanty
substancje powierzchniowo czynne
NMR spectroscopy
nuclear magnetic resonance spectroscopy
surfactants
surface active agents
Opis:
Za pomocą spektroskopii NMR zbadano sześć (3 anionowe i 3 niejonowe) spośród najpowszechniej stosowanych surfaktantów. Wyznaczono zakresy przesunięć chemicznych charakterystyczne dla poszczególnych substancji. Wyznaczono krzywe wzorcowe pozwalające selektywnie oznaczać zawartość anionowych surfaktantów w zakresie stężeń od 0,1-20 g m-3. Skuteczność metody oznaczania ilościowego zweryfikowano badając sporządzone mieszaniny surfaktantów oraz środowiskowe próbki wody.
Źródło:
LAB Laboratoria, Aparatura, Badania; 2011, 16, 1; 12-14
1427-5619
Pojawia się w:
LAB Laboratoria, Aparatura, Badania
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructural analysis of poly(n-propyl acrylate) and poly(isopropyl acrylate) based on the backbone β-methylene carbon signal in the 13C NMR spectra
Analiza mikrostrukturalna poli(akrylanu n-propylu) i poli(akrylanu izopropylu) na podstawie sygnału węgla β-metylenowego w widmach 13C NMR
Autorzy:
Pasich, M.
Siołek, M.
Henzel, N.
Matlengiewicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/278863.pdf
Data publikacji:
2016
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Inżynierii Materiałów Polimerowych i Barwników
Tematy:
poly(n-propyl acrylate)
poly(isopropyl acrylate)
microstructure
NMR spectroscopy
poli(akrylan n-propylu)
poli(akrylan izopropylu)
mikrostruktura
spektroskopia NMR
Opis:
The samples of poly(n-propyl acrylate), PnPrA, and poly(isopropyl acrylate), PiPrA, were synthesized by free radical polymerization in solution (butan-2-one). The 100 MHz 13C NMR spectra of these homopolymers were recorded in two deuterated solvents: chloroform (CDCl3) and benzene (C6D6). In the PnPrA spectra, the backbone β-methylene carbon signal (β-CH2) (33.0 - 36.5 ppm) was split up to configurational hexads for CDCl3 and C6D6. In the PiPrA spectra, the β-CH2 signal (32.5 - 36.5 ppm) was split up to configurational hexads in both solvents.
Próbki poli(akrylanu n-propylu), PnPrA, i poli(akrylanu izopropylu), PiPrA, otrzymano w polimeryzacji rodnikowej w roztworze. Widma 100 MHz 13C NMR tych homopolimerów zarejestrowano w dwóch deuterowanych rozpuszczalnikach: chloroformie (CDCl3) i benzenie (C6D6). Na widmach PnPrA, zarejestrowanych w deuterowanym chloroformie i benzenie sygnał, węgli metylenowych (β-CH2) (33,0 - 36,5 ppm) ulega rozszczepieniu się na poziomie heksad konfiguracyjnych, natomiast sygnał β-CH2 (32,5 - 36,5 ppm) poli(akrylanu izopropylu) rozszczepia się na poziomie heksad konfiguracyjnych.
Źródło:
Przetwórstwo Tworzyw; 2016, T. 22, Nr 5 (173), 5 (173); 451-457
1429-0472
Pojawia się w:
Przetwórstwo Tworzyw
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructural analysis of two poly(propyl acrylates): poly(n-propyl acrylate) and poly(isopropyl acrylate), based on the carbonyl signal in the 13C NMR spectra
Analiza mikrostrukturalna dwóch poli(akrylanów propylu): poli(akrylanu n-propylu) i poli(akrylanu izopropylu), na podstawie sygnału węgla karbonylowego w widmach 13C NMR
Autorzy:
Pasich, M.
Henzel, N.
Matlengiewicz, M
Powiązania:
https://bibliotekanauki.pl/articles/946319.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Inżynierii Materiałów Polimerowych i Barwników
Tematy:
poly(n-propyl acrylate)
poly(isopropyl acrylate)
microstructure
NMR spectroscopy
poli(akrylan n-propylu)
poli(akrylan izopropylu)
mikrostruktura
spektroskopia NMR
Opis:
The samples of poly(n-propyl acrylate), PnPrA, and poly(isopropyl acrylate), PiPrA, were synthesized by free radical polymerization in solution (butan-2-one). The 100 MHz 13C NMR spectra of these homopolymers were recorded in two deuterated solvents: chloroform (CDCl3) and benzene (C6D6). In the spectra of both PnPrA and PiPrA recorded in CDCl3 the carbonyl signal was split at the level of configurational triads, while in C6D6 this signal revealed heptad splitting for PiPrA and pentad splitting for PnPrA.
Próbki poli(akrylanu n-propylu), PnPrA, i poli(akrylanu izopropylu), PiPrA, otrzymano w polimeryzacji rodnikowej w roztworze butan-2-onu. Widma 100 MHz 13C NMR tych homopolimerów zarejestrowano w dwóch deuterowanych rozpuszczalnikach: chloroformie (CDCl3) i benzenie (C6D6). Na widmach PnPrA i PiPrA, zarejestrowanych w deuterowanym chloroformie, sygnał węgli karbonylowych (C=O) ulega rozszczepieniu na poziomie triad konfiguracyjnych, podczas gdy dla deuterowanego benzenu sygnał C=O PiPrA rozszczepia się na poziomie heptad, a dla PnPrA pentad konfiguracyjnych.
Źródło:
Przetwórstwo Tworzyw; 2018, T. 24, Nr 1 (181), 1 (181); 56-63
1429-0472
Pojawia się w:
Przetwórstwo Tworzyw
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The gyrotron for DNP-NMR spectroscopy: A review
Autorzy:
Nowak, Kacper
Powiązania:
https://bibliotekanauki.pl/articles/2173563.pdf
Data publikacji:
2022
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
DNP-NMR spectroscopy
gyrotron stability
gyrotron tuning
dynamic nuclear polarization
spektroskopia magnetycznego rezonansu jądrowego
stabilność żyrotronu
strojenie żyrotronu
Opis:
This paper outlines the principle of the DNP-NMR technique. The gyrotron, as a very promising microwave source for NMR spectroscopy, is evaluated. Four factors: power stability, power tuning, frequency stability, and frequency tuning determine the usability of the gyrotron device. The causes of instabilities, as well as the methods of overcoming limitations and extending usability are explained with reference to the theory, the numerical and experimental results reported by gyrotron groups.
Źródło:
Bulletin of the Polish Academy of Sciences. Technical Sciences; 2022, 70, 1; e140354, 1--13
0239-7528
Pojawia się w:
Bulletin of the Polish Academy of Sciences. Technical Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
15N magnetic relaxation study of backbone dynamics of the ribosome-associated cold shock response protein Yfia of Escherichia coli
Autorzy:
Zhukov, Igor
Bayer, Peter
Schölermann, Beate
Ejchart, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/1040866.pdf
Data publikacji:
2007
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
anisotropic overall molecular diffusion
model-free approach
15N NMR spectroscopy
stress adaptation
disordered polypetide chain motion
protein Y
Opis:
In the solution structure of the ribosome-associated cold shock response protein Yfia of Escherichia coli in the free state two structural segments can be distinguished: a well structured, rigid N-terminal part displaying a βαβββα topology and a flexible C-terminal tail comprising last 20 amino-acid residues. The backbone dynamics of Yfia protein was studied by 15N nuclear magnetic relaxation at three magnetic fields and analyzed using model-free approach. The overall diffusional tumbling of the N-terminal part is strongly anisotropic with a number of short stretches showing increased mobility either on a subnanosecond time scale, or a micro- to millisecond time scale, or both. In contrast, the unstructured polypeptide chain of the C-terminal part, which cannot be regarded as a rigid structure, shows the predominance of fast local motions over slower ones, both becoming faster closer to the C-terminus.
Źródło:
Acta Biochimica Polonica; 2007, 54, 4; 769-775
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Novel synthesis of 3-(((E)-benzylidene)amino)-5-((Z)-3,4-dimethoxybenzylidene)-2-phenyl-3,5-dihydro-4H-imidazol-4-one derivatives as potent antimicrobial agents
Autorzy:
Manawar, Rohit B.
Parmar, Mukesh B.
Nayaka, Indresh J.
Pandit, Brinda H.
Shah, Manish K.
Powiązania:
https://bibliotekanauki.pl/articles/1066261.pdf
Data publikacji:
2019
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
4H-imidazol-4-one
A. niger
Anti-fungal
Anti-microbial Agent
Bioactivity
C. albicans
E. coli
Elemental analysis
IR spectroscopy
Mass spectroscopy
NMR spectroscopy
P. aeruginosa
S. aureus
S. pyogenes
Opis:
Novel synthesis of 4H-imidazol-4-one derivative by reaction of (Z)-3-amino-5-(3,4 dimethoxybenzylidene)-2-phenyl-3,5-dihydro-4H-imidazol-4-one with derivative of different aromatic aldehydes and Salicyldehyde. New synthesized compound are thermally stable and neither air-nor moisture sensitive at RT. Successive library of synthesized compound characterized using IR, NMR, Elemental, Mass, and its antimicrobial activity study.
Źródło:
World Scientific News; 2019, 130; 42-70
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badanie struktury i dynamiki N-terminalnych sekwencji dermorfiny i ich analogów z wykorzystaniem spektroskopii NMR w ciele stałym i rentgenografii
Studies on the structure and dynamics of N-terminal sequences of dermorphin and their analogs by means of solid state NMR spectroscopy and XRD
Autorzy:
Trzeciak-Karlikowska, K.
Powiązania:
https://bibliotekanauki.pl/articles/171648.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
peptydy opioidowe
oddziaływania CH-pi
dynamika molekularna
oddziaływanie peptyd–fosfolipid
spektroskopia NMR
1H Ultra Fast MAS NMR
PISEMA MAS
PILGRIM
XRD
opioid peptides
CH-pi interactions
molecular dynamics
peptide–phospholipid interaction
NMR spectroscopy
Opis:
Deltorphin I (Tyr-d-Ala-Phe-Asp-Val-Val-Gly-NH_2) and dermorphin (Tyr-d-Ala-Phe- -Gly-Tyr-Pro-Ser-NH_2) are natural opioid peptides that have been isolated from the skin of South American frogs [1]. The presence of d-amino acid is crucial for their biological activity. The synthetic analogs of given heptapeptides containing l-alanine are not analgesics [2]. Analysis of the influence of stereochemistry on molecular packing, dynamics and biological functions of neuropeptides is still important for receptor studies and practical applications (e.g. design of new selective pain killers). Presented research is focused on the structure and dynamics of two N-terminal sequences of dermorphin: tripeptide Tyr-d-Ala-Phe 1, tetrapeptide Tyr-D-Ala-Phe-Gly 2, and their analogs with l-alanine: Tyr-Ala-Phe 3 and Tyr-Ala-Phe-Gly 4, using solid state NMR and X-ray diffraction. This study clearly demonstrates that 1 and 2 crystallized under different conditions to form exclusively one structure [3, 4]. In contrast, tripeptide and tetrapeptide with l-Ala in the sequence very easily form different crystal modifications. Tyr-Ala-Phe 3 crystallizes into two forms: 3a and 3b [5], while Tyr-Ala-Phe-Gly 4 gives three modifications: 4a, 4b and 4c [4]. It seems that one of the factors, which can be important in the preorganization mechanism anticipating the formation of crystals, is the intramolecular CH-đ interaction between aromatic rings of tyrosine and/or phenylalanine and the methyl group of alanine. Such interaction is possible only for d-Ala residue. For l-Ala in the peptide sequence, the methyl group is aligned on the opposite side with respect at least to one of the aromatic groups. It can be further speculated that such internal CH-π contacts can also occur during the interaction of ligand–receptor, making the message sequence of opioid peptides more rigid and finally selective. By employing different NMR experiments (e.g. PISEMA MAS and PILGRIM) it was proven that the main skeleton of analyzed peptides is rigid, whereas significant differences in the molecular motion of the aromatic residues were observed [4, 6]. Solid state 2H NMR spectroscopy of samples with deuterium labeled aromatic rings: Tyrd4-d-Ala-Phe 5, Tyr-d-Ala-Phed5 6, Tyrd4-Ala-Phe 7, Tyr-Ala-Phe^d5 8 was used to analyze the geometry and time scale of the molecular motion. At ambient temperature, the tyrosine ring of sample 5 is rigid and in the sample 6 the phenylalanine ring undergoes a "π -flip". The tyrosine rings of form I of 7 and 8 are static, while the phenylalanine rings of form II of 7 and 8 undergo a fast regime exchange [6]. Variable temperature 2H measurements proved that the tyrosine and phenylalanine rings of two forms of compounds 7 and 8 became more mobile with increasing temperature. In contrast, the aromatic rings of samples 5 and 6 preserve their dynamics regime (static tyrosine and "π -flip" phenylalanine) in a large range of temperatures [6]. The analysis of 13C, 15N labeled tetrapeptide Tyr-D-Ala-Phe-Gly 2’-phospholipid membrane interactions suggests that peptide 2’ is aligned on the surface of the membrane (RFDR MAS) and the sandwich-like π -CH_3-π arrangement of the pharmacophore is preserved (DARR) [7].
Źródło:
Wiadomości Chemiczne; 2012, 66, 9-10; 867-891
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Synthesis and evaluation of effectiveness of a controlled release preparation 2,4-D: a reduction of risk of pollution and exposure of workers
Autorzy:
Kowalski, W. J.
Romanowska, I.
Smol, M.
Silowiecki, A.
Głazek, M.
Powiązania:
https://bibliotekanauki.pl/articles/204646.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
acids
2,4-dichlorophenoxy acetic acid (2,4-D)
controlled release
ring opening polymerization of B-butyrolactone
SEC
ESI-MS characterization of oligomers
NMR spectroscopy
assessment of herbicide effectiveness
Opis:
A novel herbicidal controlled release formulation composed of (2,4-dichlorophenoxy) acetic acid (2,4-D) chemically bonded to biodegradable (R,S)-3-hydroxybutyric acid oligomers was investigated. The synthesis of (R,S)-3-hydroxy butyric acid oligomers was carried out via the ring opening polymerization of â-butyrolactone initiated by 2,4-dichlorophenoxy acetic potassium salt in the presence of complexing agents. The formed oligomers were characterized by size exclusion chromatography, proton magnetic resonance and electrospray mass spectrometry in order to fi nd out their molar mass distribution and molecular structures. An assessment of biological effectiveness of the obtained herbicidal formulation was carried out in the greenhouse vs. Sinapis alba var. Nakielska. A promotion of the controlled release formulation with decreased water solubility and with low vapor pressure of the active ingredient, instead of traditional formulations of 2,4-dichlorophenoxy acetic acid may help to ensure a greater safety for workers and reduce the risk of dissemination of the active ingredient in the soil profile.
Źródło:
Archives of Environmental Protection; 2012, 38, 3; 119-129
2083-4772
2083-4810
Pojawia się w:
Archives of Environmental Protection
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 23

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