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wizyta

od 2020-09-20

Dr Farhod Nozirov  | 1999-10 <> 2006-06

Stażysta podoktorski

  6508162929  

Publikacje                          Seminaria


8.

Nozirov F., Fojud Z., Jancelewicz M., Nazirov A., Jurga S.

Molecular motion in the biocopolymer sequence of glycolide and lactide studied by solid state NMR This paper reports a nuclear magnetic resonance study of the molecular motion in copolymers derived from glycolide and L-lactide in the solid state. Variation of T-1 relaxation times with temperature reflects a local disorder and the fast segment conformational motions which can be quantified in terms of correlation times predicted by the Bloembergen-Purcell-Pound and Davidson-Cole models. At low temperatures, spin relaxation is dominated by the axial methyl rotation in lactide units described by an asymmetry parameter of the correlation time delta which takes a value of about 0.45 for all systems. Above the devitrification points the trans and gauche isomerization in glycolide segments occurs. In addition to the chemical structure characterization, solid-state magic-angle spinning spectroscopy gives an insight into the role of glycol segments in the chain mobility.

Applied Magnetic Resonance, 34(1-2), 193-203 (2008)

DOI: 10.1007/s00723-008-0102-z   (Pobrane:  2020-10-23)


7.

Nozirov F., Nazirov A., Jurga S., Fu R.

Molecular dynamics of poly(L-lactide) biopolymer studied by wide-line solid-state 1H and 2H NMR spectroscopy The molecular dynamics of poly(L-lactide) (PLLA) biopolytner was characterized through analyses of H-1 and H-2 NMR line-shapes and spin-lattice relaxation times at different temperatures. At low temperatures (e.g. 90K), the methyl group rotation is dominant leading to a significant reduction in the proton second moment. Fast methyl group reorientation occurs at ca. 130 K. In additional to the fast methyl group rotation, hydroxyl groups start to reorient as the temperature increases further, eventually leading to the breakdown of the segments of the biopolymer chains above its glass transition temperature Tg of 323K. The analyses of the H-2 NMR line-shapes indicate that both the methyl and hydroxyl reorientations can be described by the so-called cone model, in which the former has three equilibrium positions with theta(C-D) = 70.5 degrees and phi = 120 degrees while the latter one exhibits two equilibrium positions with theta(C-D) = 78 degrees and phi = 180 degrees.
(C) 2005 Elsevier Inc. All rights reserved.

Solid State Nuclear Magnetic Resonance, 29(4), 258-266 (2006)

DOI: 10.1016/j.ssnmr.2005.09.001   (Pobrane:  2020-10-21)


6.

Gnatyuk I., Puchkovska G., Chashechnikova I., Nozirov F., Jurga S., Peplińska B.

1H NMR study of hydrogen bonding and molecular dynamics of 5CB confined to molecular sieves It has been found that the main mechanism of H-1 protons spin-lattice relaxation of bulk 5CB at 200 MHz is its intramolecular motion, namely, the reorientation of CH2 and CH3 groups of its alkyl chain. Activation parameters of such motions have been estimated. Drastic decrease in proton spin-lattice relaxation times at the nematic-to-isotropic phase transition can be explained by the activation of molecular translational diffusion and reorientations around long and short molecular axes of bulk 5CB. Our NMR analysis revealed the slowing-down of molecular dynamics of confined 5CB molecules and their fragments. This can be explained by the interaction of some part of 5CB molecules with the surface active Si(Al)-OH centers of MCM matrix via hydrogen bonds of Si(Al)-(OHN)-N-... drop C-type.
(C) 2004 Elsevier B.V. All rights reserved.

Journal of Molecular Structure, 700(1-3), 183-189 (2004)

DOI: 10.1016/j.molstruc.2004.01.048   (Pobrane:  2020-10-21)


5.

Gnatyuk I., Galdyna O., Chashechnikova I., Nozirov F., Jurga S., Peplińska B.

1H NMR spectra of 5CB liquid crystal and 5CB-MCM heterogeneous system It is shown that, in the 1H NMR spectra of 5CB, the splitting of proton bands is the result of the dipole-dipole interaction. Using the value of the splitting of the 1H bands, we determined the order parameters S for some fragments of 5CB molecules in the nematic phase. It is found that the values of S for the biphenyl core are twice greater than that for alkyl radical, which is the evidence for different dynamics of these structure fragments. From the analysis of the form of bands in the 1H spectra in the hetereogeneous system 5CB-MCM, we showed that, in the temperature range of the existence of the nematic and crystal phases of bulk 5CB, there is no ordering of these molecules in the channels of MCM. This is caused by the appearance of defects in the liquid crystal ordering due to the interaction of some part of the LC molecules with the active centers of the surface of MCM channels.

Proceedings of SPIE - XVI International Conference on Spectroscopy of Molecules and Crystals, 5507, (2004)

DOI: 10.1117/12.569807
ISBN: 9780819454447   (Pobrane:  2021-01-11)


4.

Nozirov F., Szcześniak E., Fojud Z., Dobrzyński P., Klinowski J., Jurga S.

1H and 13C NMR studies of molecular dynamics in the biocopolymer of glycolide and epsilon-caprolactone Copolymers of glycolide and F-caprolactone were studied using differential scanning calorimetry and solid-state NMR. The variation of the T-1 relaxation time with temperature reflects local disorder and can be quantified in terms of the distribution of correlation times predicted by the Davidson-Cole model. T-1 relaxation is dominated by trans gauche lisomerisation, with an activation energy of 34-35 kJ mol(-1).
(C) 2002 Elsevier Science (USA).

Solid State Nuclear Magnetic Resonance, 22(1), 19-28 (2002)

DOI: 10.1006/snmr.2002.0056   (Pobrane:  2020-10-21)


3.

Nozirov F., Fojud Z., Klinowski J., Jurga S.

High-resolution solid-state 13C NMR studies of poly[(R)-3-hydroxybutyric] acid Solid poly[(R)-3-hydroxybutyric] acid was examined by high-resolution C-13 MAS NMR, differential scanning calorimetry and infrared spectroscopy. The C-13 methyl group resonance consists of three components: the rigid amorphous phase, the crystalline phase and the mobile amorphous phase. Spectral deconvolution, using the Lorentz function, reveals the relative amounts as 62% crystalline and 38% amorphous at 333 K, and 42% crystalline, 40% pure amorphous and 18% beta-orthorhombic at 413 K. NMR indicates a large difference in molecular mobility between the crystalline and amorphous regions of the sample. Infrared spectroscopy shows that the stretching at 1725 cm(-1) (characteristic of the a-form) comes from the crystalline region, and the bands at 1744 cm(-1) (characteristic of the beta-form) and 1800 cm(-1) come from the amorphous region.
(C) 2002 Elsevier Science (USA).

Solid State Nuclear Magnetic Resonance, 21(3-4), 197-203 (2002)

DOI: 10.1006/snmr.2002.0060   (Pobrane:  2020-10-23)


2.

Nozirov F., Kozak M., Domka L., Jurga S.

NMR relaxation studies of polyhydroxybutyric acid (PHB) biodegradation by Escherichia Coli In the paper the biodegradation process of polyhydroxybutyric acid (PHB) copolymer, induced by Escherichia coli bacteria is monitored using nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM).

Molecular Physics Reports, 33, 102-105 (2001)

WWW: http://www.ifmpan.poznan.pl/mol/
ISSN: 1505-1250   (Pobrane:  2021-01-07)


1.

Nozirov F., Fojud Z., Szcześniak E., Jurga S.

Molecular dynamics in poly[(R)-3-hydroxybutyric acid] biopolymer as studied by NMR Nuclear magnetic resonance line shapes and spin-lattice relaxation rimes T-1 of H-1 and H-2 nuclei of poly[(R)-3-hydroxybutyric acid] have been measured in the temperature range 100-413 K. The results provide information on the local dynamics of the compound. Activation parameters of the revealed motion are determined.

Applied Magnetic Resonance, 18(1), 37-45 (2000)

DOI: 10.1007/BF03162097


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