Ireneusz Natkaniec

Optical nonlinearity and electric conductivity origin study on sucrose crystal by using IR, Raman, INS, NMR, and EPR spectroscopies.

The supposed importance of hydrogen bonds toward the origin of second harmonic generation (SHG) and electric conductivity in crystalline sucrose was investigated by IR (4000-10cm(-1)), INS (2000-10cm(-1), at 35K), polarized Raman (3600-50cm(-1)) spectra, and (1)H NMR second moment line records in the temperature range 450-80K. The temperature dependence of NIR (7000-5500cm(-1)) polarized spectra gave information about -CH2 motions complementary to NMR results concerning -CH2OH group rearrangements. The EPR spectra were applied to study the generation of radical ions by exposure to NIR radiation. Density functional theory quantum chemical calculations were performed to reproduce the vibrational spectra in order to complete as far as possible the assignments of bands observed by us and in the literature in sucrose crystals, and to throw more light on the possible reasons of sucrose electric conductivity and optical nonlinearity by the knowledge of theoretical values of dipole moments, polarizabilities, first order hyperpolarizabilities of sucrose molecule and clusters as well as ionization energy and electron affinity. The proton transfer in one specific hydrogen bond parallel to the helical axis b is proposed to be the most important in SHG and conductivity origin.

Neutron scattering from graphene oxide paper and thermally exfoliated reduced graphene oxide

E. F. Sheka, I. Natkaniec, V. Mel’nikov, K. Druzbicki Peoples’ Friendship University of Russia, Miklukho-Maklaya Str. 6, 117198 Moscow, Russia Faculty of Physics, Adam Mickiewicz University, Umultowska Str. 85, 61-614 Poznań, Poland Semenov Institute of Chemical Physics RAS, Kosyguina str. 4, 119991 Moscow, Russia Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Joliot-Curie Str. 6, 141980 Dubna, Russia sheka@icp.ac.ru, inat@amu.edu.pl, melnikov@center.chph.ras.ru

Inelastic Neutron Scattering (INS) Study of Low Frequency Vibrations and Hydrogen Bonding of (E)-2-Hydroxyimino-2-Cyanoacetic Acid Ethyl Ester

Abstract The title unsubstituted (normal) (E)-2-hydroxyimino-2-cyanoacetic acid ethyl ester (the abbreviated name: (E)-2-cyanoethyl ester-2-oxime or 2-oxime) and its 2-deuterated analogue have been prepared and characterized using infrared, Raman and inelastic, incoherent neutron scattering (IINS) spectroscopy. Molecular structures (molecular conformations) of the compounds are proposed for the vapour state. Four molecular conformers, namely two pairs of the s-cis, s-trans rotational isomers (rotamers) from six lower energetic conformations of E-2-hydroxyimino-2-cyanoacetic ethyl ester, are predominating for the single molecule of the compound. They amount together to almost 100% of the conformational populations of both rotational isomers as it was theoretically calculated using DFT (B3LYP) method with 6-311G++(d,p) basis set. Additionally dimers of 2-oxime were considered using B3LYP/6-31G* method in order to improve the results obtained for single molecule. In both parent (=N–OH) and deuterated (=N–O–D) molecules of the (E)-2-ethylcyano ester-2-oxime respectively, extra bands corresponding primarily to hydrogen (deuterium) bond vibrations (γ–bending out of plane of hydrogen bond, σ–stretching of hydrogen bond bridge, δ–bending in plane of hydrogen bond, λ–bending of hydrogen bond bridge have been identified, namely σ (N–O–H···O) at 132.8, 212.5, 279, 358.7, 424, 448, 523.6, 872, γ (N–O–H···O) at 334, 564, 592, 745, 820, δ (N–OH···O) at 1461, 1600, 1862cm−1 in the low temperature IINS spectrum, whereas the frequency at 365cm−1 has been assigned as the out of plane (o.o.p.) (γO–D···O) vibrational mode. Formation of the O–H···O hydrogen bridge is reflected in shifting of the bands of the stretching and bending vibrations of OH group as well as arising of the bridge vibrations in the low frequency range. Moreover, equilibrium geometries and all harmonic vibrational frequencies of the (E)-2-cyano ethyl ester-2-oxime molecules with potential energy distribution (PED) were also calculated by means of the above mentioned theoretical programs.

Inelastic Neutron Scattering (INS) Study of Low Frequency Vibrations and Hydrogen Bonding of (E)-Benzil Monoxime

Abstract (E)-benzil monoxime (or (E)-monoxime of 1,2 diphenyloetandion), which is the subject of this paper, belongs to the family of bioactive organic substances. Many of them have been investigated for many years by inelastic, incoherent neutron scattering spectroscopy (IINS) but the investigation of (E)-benzil monoxime is absent from literature. Therefore (E)-benzil monoxime has been investigated using infrared, and IINS spectroscopy. Dimers of (E)-benzil monoxime were considered using B3LYP functional (connection of Becke and Lee–Yang–Parr functionals) combined with the 6-311++G(d,p) basis set method of quantum chemistry in order to improve the results obtained for a single molecule. In (E)-benzil monoxime, extra bands corresponding primarily to hydrogen bond vibrations (γ bending out of plane of hydrogen bond at 312.3, 372, 470.5, 578.3, 703.5, 748.7, 780.4u2009cm–1, σ stretching of hydrogen bond bridge at 124.3, 140.9, 176.5, 190.1, 223.6, 259.1, 290.5, 501.8, 623.5u2009cm–1, δ bending in plane of hydrogen bond at 1102.4, 1371,1452,1535, 1630.6u2009cm–1, λ bending of hydrogen bond bridge at ca. 40u2009cm–1, ν stretching band OH at 3397u2009cm–1) have been identified. Some of them could be discovered only by using IINS method and this is the main result of this work. Additionally wed like to compare the structure of the compound and the structure of oximes previously investigated by us . Taking into account the structure and IINS results for three oximes investigated by us, we can estimate the difference of hydrogen bond power in those three oximes. Hence the power of hydrogen bond in the (E)-benzil monoxime seems to be the smallest in the group of the three compounds: (E)-benzil monoxime, (E)-2-hydroxyimino-2-cyanoacetic acid ethyl ester (2-oxime), acid K salt of 2-oxime.

Inelastic Neutron Scattering (INS) Study of Low Frequency Vibrations of Acid K Salt of (E)-2-Hydroxyimino-2-Cyanoacetic Acid Ethyl Ester and its Phase Situation by DSC Method

Abstract The acid potassium salt of (E)-2-hydroxyimino-2-cyanoacetic acid ethyl ester (in other words: the acid Ksalt of (E)-2-cyanoethyl ester of 2-oxime or acid Ksalt of 2-oxime, or shortly speaking acid Ksalt-) has been prepared and characterized using inelastic, incoherent neutron scattering (IINS or shortly speaking INS). The last results have been compared with those obtained from optical spectroscopy. Additionally, dimers of the acid Ksalt of 2-oxime were considered i.e. vibrational frequencies of such dimers have been calculated using RB3LYP method [20] with basis set 6-311++G(d, p). In the molecule of the acid Ksalt of 2-oxime, extra bands corresponding to hydrogen bond vibrations (λ – bending of hydrogen bond bridge, σ – stretching of hydrogen bond bridge, γ – bending out of plane of hydrogen bond, ν – stretching –OH, δ – bending in plane of hydrogen bond have been identified, namely λ at ca. 20, σ (N–O–H···O) at 109.7, 132.3, 154.8, 206.8, 248.5, 255.1, 303.9, 339.2, 359.4, 396.6, 428.8, 483.3, 537, 577.8, 782.4, 815.3, 894.7,1108, 1165. 1408.7, γ (N–O–H···O) at 1298, ν at 1583.1 cm-1, δ (N–OH···O) at 1734.4 and at 1847.4 cm-1, in the low temperature IINS spectrum. Formation of the O–H···O hydrogen bridge in the acid Ksalt of 2-oxime in comparison with the same O–H···O hydrogen bridge in pure 2-oxime is reflected in shifting of the bands of the stretching (to lower) and bending vibrations (to higher) of OH group frequencies confirming the fact of increasing of hydrogen bond power in the acid Ksalt of 2-oxime in comparison with hydrogen bond power of pure 2-oxime. Additionally the fact that acid Ksalt melts ca. 50 K higher than 2-oxime and the shorter length of hydrogen in acid Ksalt than in 2-oxime confirm the greater hydrogen bond power in the acid Ksalt than in 2-oxime.