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•Spectral properties of (FH4C6)NHCHC(CN)(COCH3) have been studied.•ZZa and EZa conformers of the molecule were determined as the most stable.•The dependence on the solvent polarity ...for the existence of ZZa/EZa conformers has been found.•The assignment of normal vibrational modes based on PED calculation has been done.
The isomers and conformers of push–pull 3-fluorophenylamino-2-acetyl propenenitrile (FH4C6)NHCHC(CN)(COCH3) (FPAAPN) have been studied experimentally by NMR and vibrational spectroscopy and theoretically by ab initio calculations at MP2 and DFT B3LYP levels in various basis sets. The IR and Raman spectra of FPAAPN as a solid and as a solute in various solvents have been recorded. The NMR spectra were obtained in chloroform, acetone, acetonitrile and dimethylsulfoxide at room temperature.
FPAAPN was prepared as a pure Z-isomer with an intramolecular hydrogen bond. According to the NMR spectra in chloroform the studied compound exists as a single ZZa entity. On the other hand, in more polar solvents the isomerization process occured and an additional EZa confomer was detected. The influence of the environment polarity on this conformational equilibrium is discussed with respect to the SCRF solvent effect calculations using IEFPCM model.
The observed IR and Raman bands were compared with calculated MP2/6-311G∗∗ harmonic vibrational frequencies and assigned on the basis of potential energy distribution.
The isomers and conformers of four push–pull compounds: methyl-2-cyano-3-methoxyacrylate (MCMA) H
3C
O
CH
C(CN)(COOCH
3), methyl-2-cyano-3-aminoacrylate (MCAA) H
2N
CH
C(CN)(COOCH
3), ...methyl-2-cyano-3-methylaminoacrylate (MCMAA) H
3C
NH
CH
C(CN)(COOCH
3) and methyl-2-cyano-3-dimethylaminoacrylate (MCDMAA) (H
3C)
2N
CH
C(CN)(COOCH
3) have been studied experimentally by vibrational and NMR spectroscopy and theoretically by the ab initio calculations at MP2 level in 6-311++G
** basis set. The IR and Raman spectra of all compounds as a solid and solute in various solvents have been recorded in the region 4000–50
cm
−1. The NMR spectra were obtained in chloroform, acetonitrile and DMSO at room temperature.
Because both electron-withdrawing groups are different, all studied compounds can exist as E and Z isomers and then conformational possibilities are given by the rotation of the methylester and methoxy or methylamino groups. NMR spectra revealed that both MCMA and MCDMAA compounds without the possibility of intramolecular hydrogen bonding were prepared as a pure E isomer whereas in the case of the compounds with the possibility of intramolecular bonding MCAA and MCMAA a mixture of both E and Z isomers was obtained.
X-ray analysis shows the presence of two EZ and EE conformers in solid MCMA. For this compound the possible second conformer was detected by NMR in more polar solvent DMSO. Vibrational spectra revealed the existence of two EZa and EEa conformers with Z and E orientation of methylester group and with
anti orientation of dimethylamino group for MCDMAA. For MCAA and MCMAA the Z isomer with Z orientation of methylester group and with intramolecular hydrogen bond is the most stable one. In more polar surrounding (DMSO) the isomerization of ZZ or ZZa conformers of MCAA and MCMAA, respectively to E isomers occurred. These experimental findings have been supported by ab initio solvent effect calculations.
The IR, Raman and NMR spectra of 3-
N,
N-dimethylhydrazino-2-acetyl propenenitrile (DMHAP) (H
3C)
2N
NH
CH
C(CN)(COCH
3) were measured. X-ray analysis revealed that DMHAP exists in solid state as
ZZa ...conformer. Vibrational and NMR spectra confirmed the existence of only one
ZZa conformer with an intramolecular hydrogen bond in less polar solvents and next two
EZa and
EZs conformers of
E-isomer with
Z-orientation of acetyl group and
anti and
syn orientation of dimethylhydrazino group in more polar environments. The observed IR and Raman bands were compared with harmonic vibrational frequencies, calculated using ab initio MP2 and DFT/B3LYP methods in 6-31G∗∗ basis set, and assigned on the basis of potential energy distribution.
In addition, the geometries and relative energies of the possible isomers and conformers of DMHAP were also evaluated on the same levels and compared with the X-ray data. The influence of environment polarity on this conformational equilibrium is discussed with respect to the SCRF solvent effect calculations using IEFPCM model.
The IR and Raman spectra of aminomethylene-malonic acid dimethylester (AMDME) NH
2
CH
C(COOCH
3)
2 and its
N-methyl derivatives (MAMDME and DMAMDME) were measured in solid phase and in different ...solvents at various temperatures. X-ray analysis revealed that AMDME exists in solid phase as
EZ conformer, MAMDME as
ZZa conformer and DMAMDME as
ZE conformer (the first and second
E or
Z letters express the orientation of the carbonyl oxygen to the C
C double bond for
trans and
cis methylester group, respectively, and the third letter
a denotes
anti position of methylamino group with respect to the C
C double bond). In less polar solutions dominantly two
ZZ and
EZ conformational forms of AMDME and
ZZa and
EZa of MAMDME are observed, whereas in more polar environments a third conformational form (
ZE and
ZEa, respectively) also appeared.
The behaviour of DMAMDME is different because there is no intramolecular hydrogen bond and in less polar solutions exists in two
ZZ and
ZE conformational forms. Very weak indications of a third conformational form (probably
EZ conformer) were observed only in more polar surroundings. From the solution IR temperature dependent spectra the energy difference between
ZE and
ZZ conformers of ΔH
=
1.8
±
0.5
kJ
mol
–1 in chloroform and ΔH
=
4.2
±
0.5
kJ
mol
–1 in acetonitrile was estimated with the
ZZ one being more stable.
The geometries and relative energies of the possible conformers of all three compounds were evaluated using
ab initio MP2 and DFT B3LYP methods in 6-31G
∗∗ basis set with PCM solvent effect inclusion. The influence of environment polarity on the conformational equilibrium is discussed.
Cyclohexadepsipetides enniatin B, B1 and G were isolated from the cultivation broth of Fusarium dimerum Penzig, an endophyte of Magnolia x soulangeana. Their production was about 350 mg l(-1) after ...96 h of submerged cultivation in Sabouraud maltose medium. Isolated enniatins inhibited growth of selected microorganisms and activity of 12-lipoxygenase with IC50 = 0.73 mg l(-1).
The IR, Raman and NMR spectra of 3-
N,
N-dimethylhydrazino-2-methylsulfonyl propenenitrile (DMHSP) (H
3C)
2N
NH
CH
C(CN) (SO
2CH
3) as a solid and in different solvents were measured. The spectra and ...X-ray analysis revealed that DMHSP was prepared as a pure
E-isomer and
E-
syn conformer with the
syn orientation of
N,
N-dimethylhydrazino group towards the C
C double bond in the solid state. Due to the low barrier practically free isomerization process occurred in solutions at room temperature. DMHSP exists in more polar solvents as pure
E-isomer in conformational equilibrium between
E-
syn and
E-
anti but in a less polar solvent the presence of
Z-isomer was observed as well. From the IR and NMR temperature dependence spectra in polar solvents the energy difference between
E-
anti and
E-
syn of Δ
H
=
2.3
±
0.9
kJ/mol and Δ
H
=
3.2
±
0.4
kJ/mol, respectively, was estimated with the
syn one being more stable.
The geometries and relative energies of possible conformers of DMHSP were evaluated using ab initio MP2 and B3LYP density functional methods in 6-31G
∗∗ basis set and compared with the X-ray data. The interpretation of NMR spectra was supported by ab initio MP2 calculations. The influence of solvent polarity on the conformational equilibrium is discussed with respect to the SCRF solvent effect calculations using PCM model. In addition, the observed IR and Raman bands were compared also with harmonic vibrational frequencies, calculated on the same levels of theory, and assigned on the base of potential energy distribution.
The isomers and conformers of two push–pull hydrazines: 3-
N,
N-dimethylhydrazino-2-acetyl propenenitrile (H
3C)
2N
NH
CH
C(CN)(COCH
3) (DMHAP) and 3-
N,
N-dimethylhydrazino-2-methylsulfonyl ...propenenitrile (H
3C)
2N
NH
CH
C(CN)(SO
2CH
3) (DMHSP) have been studied experimentally by NMR and vibrational spectroscopy and theoretically by the ab initio calculations at MP2 level in 6-31G** basis set. The IR and Raman spectra of both compounds as a solid and solute in various solvents have been recorded. The NMR spectra were obtained in chloroform and DMSO at room temperature.
Both compounds have been prepared by the same way. NMR spectra revealed that DMHAP was prepared as a pure
Z-isomer whereas in the case of DMHSP a pure
E-isomer was obtained. Due to the low barrier for both compounds practically free isomerisation process occurred in the solutions but in opposite directions. Whereas DMHAP exists in the solid state and in the less polar solvent as
Z-isomer, in more polar solvents the appearance of next two conformers of
E-isomer was observed. On the contrary DMHSP exists in the solid state and in the more polar solvent as
E-isomer only but in less polar solvent the presence of
Z-isomer was observed as well.
Conformational possibilities of both studied compounds are given by the rotation of dimethylhydrazino group with its
anti- or
syn-orientation towards the olefinic double bond. Moreover, by the rotation of the acetyl group with
Z- and
E-orientation of carbonyl bond towards olefinic double bond can occur in DMHAP. Vibrational and NMR spectra revealed the existence of single conformer with intramolecular hydrogen bond for
Z-isomer in less polar solvent and next two conformers for
E-isomer of DMHAP with
Z-orientation of acetyl group and
anti and
syn orientation of dimethylhydrazine group in more polar solvents. For
E-isomer of DMHSP two conformers with
anti or
syn orientations of dimethylhydrazino group have been also confirmed by NMR spectra in more polar solvents. Additionally the third DMHSP conformer with
anti orientation of dimethylhydrazino group originating from
Z-isomer was detected in less polar solvents. These experimental findings have been supported by ab initio calculations with solvent effect inclusion.
The first successful Pd(II)-catalysed aminocarbonylation of the highly substituted benzylaminoalkene
5 allows the direct preparation of fused piperidine lactones
3 and
4, which are subsequently ...converted to the novel C-6 homologue of 1-deoxynojirimycin
1 and 1-deoxy-
l-idonojirimycin
2. The study of the influence of various catalytic conditions on the diastereoselectivity and product distribution of the key aminocarbonylation is presented.
In vivo magnetic resonance spectroscopy (MRS) studies of glial brain tumours reported that higher grade of astrocytoma is associated with increased level of choline-containing compounds (Cho) and ...decreased levels of N-acetylaspartate (NAA) and creatine and phosphocreatine (Cr). In this work, we studied the metabolism of glioma tumours by in vitro proton magnetic resonance spectroscopy (1H-MRS). 1H-MR spectra were recorded in vitro from perchloric acid extracts of astrocytoma (WHO II) and glioblastoma multiforme (WHO IV) samples. We observed differences between astrocytoma and glioblastoma multiforme in the levels of Cho, alanine, lactate, NAA, and glutamate/glutamine. In astrocytoma samples, we found higher MR signal of NAA and lower signal of Cho and alanine. MR spectra of glioblastoma samples reported significantly higher levels of lactate and glutamate/glutamine. In contrast, levels of Cr were the same in both tumour types. We also determined NAA/Cr and Cho/Cr ratios in the tumour samples. The NAA/Cr ratio was higher in astrocytomas than in glioblastomas multiforme. Conversely, the Cho/Cr ratio was higher in glioblastoma multiforme. The results indicate that MRS is a promising method for distinguishing pathologies in human brain and for pre-surgical grading of brain tumours.
The analyses of sup.99gTc-DMSA complexes prepared under alkali and acidic reactions were reported. Modern analytical, separation and spectral methods such as NMR (¹H-NMR, sup.13C-NMR, APT, COSY and ...HSQC) and Q-TOF HPLC-MS/MS system with ESI were employed to determine the identity and characterization of the products. The structure of sup.99gTc(V)DMSA was clearly confirmed and its fragmentation path in negative and positive ionisation mode was suggested. The effect of ascorbic acid and new alternative labelling with the use of NH.sup.99g.sub.4TcOCl.sub.4 was examined. Surprisingly, sup.99gTc(III)DMSA complex was not formed under acidic reaction conditions. sup.99gTc(V)DMSA complex was the main reaction product under both experimental conditions. This result suggests the key role of sup.99g/99mTc concentration during the process of radiopharmaceuticals preparation. Keywords sup.99gTc-DMSA * NMR * HPLC-MS/MS
