某些芳香族羟肟一过渡金属配合物的红外光谱

The preparation and infrared spectroscopic studies of coordination compounds of salicylaldoxime, 2-hydroxy-acetophenone oxime, 2-hydroxy-benzophenone oxime and 2-hydroxy-4-methoxy-benzophenone oxime with copper (II), nickel (II), cobalt (II) and iron (II) have been described. The frquency of the C=N stretching vibration is usually higher in the complex than that in the ligand. The higher the frequency of the C=N vibration is, the larger the stability constant of the complex will be, but there is no quantitative relationship. In the case of complexes of salicylaldoxime with Cu, Ni, Co and Fe, &CC=N values are correlated linearly with the ionization potentials of the central metal ions. The frequency of the OH stretching vibration is closely related to the geometric configuration of the complex. Thus aromatic hydroxyoximes form coordination compound with Co (II) and Fe (II) with cis configuration possessing six membered stronger hydrogen bonding ring. This is indicated in the infrared spectra by the complete absence of the absorption band due to the OH stretching vibration, or by the appearance of an extremely broad and flat band of very low intensity. However, Cu (II) or Ni (II) complex possesses trans configuration with five membered hydrogen-bonding bridge showing characteristic OH absorption band in the infrared region. The &COH of complex investigated is closely related to the polar nature of the substituents on the benzene ring. By examining the spectra of Cu-63 and Cu-65 complexes with 2-hydroxy-4(5)-substituted benzophenone oximes, the characteristic frequencies of M -- O and M -- N in the far infrared region were assigned for a series of aromatic hydroxyoxime-transition metal complexes.     

Investigation of aromatic hydroxyoxime-transition metal complexes by infrared spectroscopy

The preparation and infrared spectroscopic studies of coordination compounds of salicylaldoxime, 2-hydroxy-acetophenone oxime, 2-hydroxy-benzophenone oxime and 2-hydroxy-4-methoxy-benzophenone oxime with copper (II), nickel (II), cobalt (II) and iron (II) are described. The frequency of the C=N stretching vibration is usually higher in the complex than that in the ligand. The higher this frequency is, the larger the stability constant of the complex will be, but there is no quantitative relationship. In the case of complexes of salicylaldoxime with Cu (II), Ni (II), Co (II) and Fe (II), v_O=N values are correlated linearly with the ionization potentials of the central metal ions. The frequency of the OH stretching vibration is closely related to the geometric configuration of the complex. Thus aromatic hydroxyoximes form coordination compounds with Co (II) and Fe (II) with cis configuration possessing six-membered hydrogen-bonded ring. This is indicated in the infrared spectra by the complete absence of the OH stretching band, or by the appearance of an extremely broad and flat band of very low intensity. However, Cu (II) or Ni (II) complex possesses trans configuration with five-membered hydrogen-bonded bridge showing characteristic OH absorption band in the infrared region. The v_oh's of complexes investigated are closely related to the polar nature of substituents on the benzene ring. By examining the spectra of ⁶³Cu and ⁶⁵Cu complexes with 2-hydroxy-4(5)-substituted benzophenone oximes in the far infrared region, the characteristic frequency of M-O and M-N were assigned for a series of aromatic hydroxyoxime-transition metal complexes.     

Investigation of complexes of octaethyltetraamidepyrophosphate (OETAPP) with uranyl salts using infrared spectroscopy

The infrared spectra of the complexes UO₂ (NO₃)₂-octaethyltetraamidepyrophosphate (OETAPP) and UO₂ Cl₂-OETAPP were investigated to test their formation and structure. Under the experimental conditions used, a stoichiometry of 1∶1 was found for both complex types.     

Fullerene bridged metallocyclodextrin donor-acceptor complexes: optical spectroscopy and photophysics

Two pyridine substituted beta-cyclodextrins have been synthesized and coordinated to the photoactive metal centres, [Ru(II)(bpy)2] and [Re(I)(CO)3bpy], where bpy is 2,2'-bipyridyl. The photophysical and electrochemical properties of these model complexes have been examined and compared with dinuclear complexes formed when C60 was included between two cyclodextrin cavities of the metallocyclodextrin units. On inclusion of C60, significant quenching of the emission of the luminophores is observed. Concentration and laser power dependence confirm that this quenching is intramolecular. The quenching process is interpreted in terms of a photoinduced electron transfer between the photosensitizer and C60 centre on the basis of spectroscopic and electrochemical evidence. Rate constants of 1.3 +/- 0.1 x 10(8) and 7.0 +/- 0.4 x 10(7) s(-1) have been determined for the Ru and Re based complexes, respectively. Significantly, these large rate constants indicate that that there is substantial electronic communication across the cyclodextrin at least for excited state processes.     

ATR and transmission analysis of pigments by means of far infrared spectroscopy

In the field of FTIR spectroscopy, the far infrared (FIR) spectral region has been so far less investigated than the mid-infrared (MIR), even though it presents great advantages in the characterization of those inorganic compounds, which are inactive in the MIR, such as some art pigments, corrosion products, etc. Furthermore, FIR spectroscopy is complementary to Raman spectroscopy if the fluorescence effects caused by the latter analytical technique are considered. In this paper, ATR in the FIR region is proposed as an alternative method to transmission for the analyses of pigments. This methodology was selected in order to reduce the sample amount needed for analysis, which is a must when examining cultural heritage materials. A selection of pigments have been analyzed in both ATR and transmission mode, and the resulting spectra were compared with each other. To better perform this comparison, an evaluation of the possible effect induced by the thermal treatment needed for the preparation of the polyethylene pellets on the transmission spectra of the samples has been carried out. Therefore, pigments have been analyzed in ATR mode before and after heating them at the same temperature employed for the polyethylene pellet preparation. The results showed that while the heating treatment causes only small changes in the intensity of some bands, the ATR spectra were characterized by differences in both intensity and band shifts towards lower frequencies if compared with those recorded in transmission mode. All pigments' transmission and ATR spectra are presented and discussed, and the ATR method was validated on a real case study. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Determination of sulphate and nitrate in plutonium compounds by infrared spectroscopy

An infrared spectrophotometric method is described for the determination of sulphate and nitrate in plutonium peroxide and plutonium tetrafluoride. Spectra of the samples in potassium bromide pellets are obtained over the 4000-4680 cm(-1) wavelength region; sulphate is determined from the absorbance of the 1103 cm(-1) absorption band and nitrate from the 1370 cm(-1) band. Data are given on the precision and accuracy for analyses of peroxide and tetrafluoride samples.     

Post-blast detection of traces of explosives by means of Fourier transform infrared spectroscopy

Samples obtained from debris after explosions of about 30 g of energetic materials were analyzed by means of Fourier transform infrared (FTIR) spectroscopy using both, Globar and synchrotron infrared radiation at the ISMI beamline of the Singapore synchrotron light source (SSLS). Low- and high-strength-of-explosion blasts were performed during each test run with the same explosive material. From the spectroscopic measurements, traces of unreacted explosives were found on more than 200 different materials that served as sample catchers in the explosions.The integrality of the experiments done confirmed that FTIR spectroscopy is a sufficiently sensitive method to detect traces of explosives in post-blast residues even of high-strength explosions. The method requires only a minimal amount of sample and enables accurate and very fast identification of the presence of explosive material. Finally, the synchrotron radiation infrared source provided one order of magnitude higher sensitivity compared to the conventional Globar source.     

Post-blast detection of traces of explosives by means of Fourier transform infrared spectroscopy

Samples obtained from debris after explosions of about 30 g of energetic materials were analyzed by means of Fourier transform infrared (FTIR) spectroscopy using both, Globar and synchrotron infrared radiation at the ISMI beamline of the Singapore synchrotron light source (SSLS). Low- and high-strength-of-explosion blasts were performed during each test run with the same explosive material. From the spectroscopic measurements, traces of unreacted explosives were found on more than 200 different materials that served as sample catchers in the explosions.The integrality of the experiments done confirmed that FTIR spectroscopy is a sufficiently sensitive method to detect traces of explosives in post-blast residues even of high-strength explosions. The method requires only a minimal amount of sample and enables accurate and very fast identification of the presence of explosive material. Finally, the synchrotron radiation infrared source provided one order of magnitude higher sensitivity compared to the conventional Globar source.     

Molecular complexes of the hydrogen halides studied by matrix isolation infrared spectroscopy

Spectroscopic studies of base—hydrogen halide complexes are reviewed, including previously unpublished data for complexes of hydrogen chloride and hydrogen bromide with a variety of bases in argon matrices. The variation of the HX stretching relative frequency shift with the hydrogen halide and with the medium (gas phase, argon matrix or nitrogen matrix) and correlations of the HX stretching and hydrogen bond bending frequencies with the proton affinity of the base and with the hydrogen bond stretching force constant or dissociation energy of the complex are discussed.     

Mass-resolved infrared spectroscopy of complexes without chromophore by nonresonant femtosecond ionization detection

Mass-resolved excitation spectroscopic techniques are usually limited to systems with a chromophore, that is, a functional group with electronic transitions in the Vis/UV, with lifetimes from hundreds of picoseconds to some microseconds. In this paper, we expand such techniques to any system, by using a combination of nanosecond IR pulses with nonresonant ionization with 800 nm femtosecond laser pulses. Furthermore, we demonstrate that the technique can achieve conformational specificity introducing an additional nanosecond IR laser. As a proof-of-principle, we apply the technique to the study of phenol(H(2)O)(1), propofol(H(2)O)(1) γ-butyrolactone(H(2)O)(n), n = 1-3, and (H(2)O)(2) complexes. While monohydrated phenol and propofol clusters permit a direct comparison with a well-studied system including an aromatic chromophore, γ-butyrolactone is a cyclic nonaromatic molecule, whose mass-resolved spectroscopy cannot be tackled by conventional techniques. Finally, we further demonstrate the potential of the technique by obtaining the first mass-resolved IR spectrum of the neutral water dimer, a nice example of a system whose ionization-based detection had not been possible to date.     

Investigation of the dislocation of natural fibres by Fourier-transform infrared spectroscopy

Dislocations were thought the weakest link in natural fibres which had negative effects on the tensile strength of the fibres. This paper presents a systematic approach to examine the dislocations in hemp fibres firstly by optical microscopy (OM) and field emission scanning electron microscopy (FE-SEM) for the morphologies of the dislocations and then by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) for the crystallinity index and hydrogen bonds and main chemical compositions of the dislocation regions in hemp fibres. The results showed that (i) dislocations resulted in fibril distortion and intensified amorphous features of hemp fibres; (ii) crystallinity index reduced from 48.4% examined by FTIR and 56.0% by XRD determination for hemps without dislocations to 41.3% for the dislocation regions; (iii) the FT-IR spectra showed much higher absorbance of hemp fibres without dislocations which was two times that of dislocation regions across the whole range of wavenumbers; (iv) deconvolving spectra in O-H stretching region showed a lower number of hydrogen bonds, weaker inter- and intra-molecular hydrogen bonding in the dislocation regions, indicating a possible decrease in the tensile strength of hemp fibres; (v) the FT-IR spectra indicated the removal of the hemicelluloses in dislocation regions and hence possible loss of lignin because of disappearing the bands at 1368 cm⁻¹, 1363 cm⁻¹ and 1506 cm⁻¹; (vi) the spectra in fingerprint region gave rise to the ratio of syringyl (S)/guaiacyl (G) of 0.9 in dislocation regions which was lower than that (1.1) of hemp without dislocation, this means a significant reduction of lignin content and a higher cellulose content in the dislocation regions.