scholarly journals Infrared Spectrum and UV-Induced Photochemistry of Matrix-Isolated Phenyl 1-Hydroxy-2-Naphthoate

Photochem ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 10-25
Author(s):  
İsa Sıdır ◽  
Sándor Góbi ◽  
Yadigar Gülseven Sıdır ◽  
Rui Fausto
Keyword(s):  
Infrared Spectroscopy ◽  
Infrared Spectrum ◽  
Uv Light ◽  
Conformational Stability ◽  
Ester Group ◽  
Intramolecular Interactions ◽  
Excitation Wavelength ◽  
Stable Form ◽  
Stable Conformer ◽  
Conformational Composition

The conformational stability, infrared spectrum, and photochemistry of phenyl 1-hydroxy-2-naphthoate (PHN) were studied by matrix isolation infrared spectroscopy and theoretical computations performed at the DFT(B3LYP)/6-311++G(d,p) level of theory. The main intramolecular interactions determining the relative stability of seven conformers of the molecule were evaluated. According to the calculations, the twofold degenerated O–H···O=C intramolecularly hydrogen-bonded conformer with the phenyl ring ester group ±68.8° out of the plane of the substituted naphtyl moiety is the most stable conformer of the molecule. This conformer is considerably more stable than the second most stable form (by ~15 kJ mol−1), in which a weaker O–H···O–C intramolecular hydrogen bond exists. The compound was isolated in cryogenic argon and N2 matrices, and the conformational composition in the matrices was investigated by infrared spectroscopy. In agreement with the predicted relative energies of the conformers, the analysis of the spectra indicated that only the most stable conformer of PHN was present in the as-deposited matrices. The matrices were then irradiated at various wavelengths by narrowband tunable UV light within the 331.7–235.0 nm wavelength range. This resulted in the photodecarbonylation of PHN, yielding 2-phenoxynaphthalen-1-ol, together with CO. The extension of the decarbonylation was found to depend on the excitation wavelength.

Comparison of the Conformational Stability for Several Vinylhalomethanes and Silanes with Experiment Using MP2 Perturbation Theory and DFT

2007 ◽  
Vol 72 (1) ◽  
pp. 15-50 ◽  
Author(s):  
Wolfgang Förner ◽  
Hassan M. Badawi
Keyword(s):  
Experimental Data ◽  
Vibrational Spectra ◽  
Recent Literature ◽  
Conformational Stability ◽  
Basis Set ◽  
Major Conclusion ◽  
Stable Conformer ◽  
Polarization Functions ◽  
Complete Series ◽  
Triple Zeta

In recent literature it was reported that the valence triple zeta basis set augmented by polarization functions is not too reliable for vinyl monohalo- and dihalomethanes and -silanes, the halogen being fluorine and chlorine. The major conclusion was that a valence triple zeta basis is too small to be augmented by polarization functions in a balanced way, at least on vinylmonofluoromethane. Thus we decided to apply the 6-311++G** basis set to the complete series of methanes, silanes and germanes (the latter ones are just added for completeness because no experimental data are available for them and, moreover, we published them already previously) and to compare the results to experimental data available in the literature to see whether the failures of this basis set show up in the complete series of molecules. In the literature we found five such molecules and the information which of the conformers is the most stable. Indeed we found that predictions on the relative stability of conformers in those systems with this basis set and MP2 as well as DFT are with a 60:40 chance, three being correct predictions and two being incorrect ones out of the five. However, since the energy differences are rather small in these systems and due to the fact that - as a consequence of twofold degeneracy of the gauche conformer on the potential curve of the torsional vibration - the abundances of the conformers in equilibrium do not change too much, we decided to calculate also vibrational spectra for three examples and to compare them also to experiment. It is reported that besides the failures in total energy (we have chosen two examples where predictions of the nature of the stable conformer are correct, and one where it is not), the vibrational spectra are rather well reproduced, especially when experimental energies are used to calculate abundances in equilibrium in the case where the prediction of the stable conformer failed.

Study of Conformational Stability of Polyacetylene Films by Infrared Spectroscopy

1991 ◽  
Vol 62-64 ◽  
pp. 511-512
Author(s):  
O.S. Roshchupkina ◽  
G.I. Kozub ◽  
L.I. Tkachenko
Keyword(s):  
Infrared Spectroscopy ◽  
Conformational Stability

Fourier-Transform Infrared Spectroscopy of Environmentally Weathered Textile Fabrics for Enhanced Microplastic Identification

2021 ◽  
Author(s):  
Shreyas Patankar ◽  
Ekaterina Vassilenko ◽  
Mathew Watkins ◽  
Anna Posacka ◽  
Peter Ross
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Fourier Transform Infrared Spectroscopy ◽  
Infrared Spectra ◽  
Environmental Fate ◽  
Uv Light ◽  
Natural Fibers ◽  
Fourier Transform Infrared ◽  
Ambient Conditions ◽  
Selection Of

<p>Microplastic pollution in oceans is among the global environmental concerns of our time. Emerging research on ocean environments indicates that microfibers, such as those originating from textiles, are some of the most commonly occurring type of microplastic contaminants. While Fourier-transform infrared spectroscopy (FTIR) is commonly used to identify and characterize pollutant samples obtained from the environment, this identification is challenging because infrared spectra of materials can be modified by exposure to the ocean, air, UV light, and other ambient conditions, in a process referred to as “weathering”. We report preliminary efforts in improving FTIR characterization of microplastics by building a library of infrared spectra of common textile fibers weathered under a selection of ambient conditions. Consumer textile materials including polyester, nylon, cotton, and other, were exposed to a selection of ambient conditions: ocean, air, and wastewater treatment stages, in a controlled weathering experiment. Infrared spectra were monitored for up to 52 weeks, with the resulting data illuminating on the environmental fate and longevity of synthetic and natural fibers. Spectral changes caused by weathering were found to depend strongly on both the composition of the material and the specific ambient conditions. This library of weathered material spectra is useful not only in easier identification of environmental microfibers, but also in helping us estimate the duration and manner of weathering that a given environmental microfiber may have experienced.</p>

Intense Photoluminescence and Photoluminescence Enhancement of Silicon Nanocrystals by Ultraviolet Irradiation

2007 ◽  
Vol 31 ◽  
pp. 74-76 ◽  
Author(s):  
P.T. Huy ◽  
P.H. Duong
Keyword(s):  
Silicon Nanocrystals ◽  
Room Temperature ◽  
Laser Excitation ◽  
Uv Light ◽  
Irradiation Time ◽  
Excitation Wavelength ◽  
Nonradiative Recombination ◽  
Emission Yield ◽  
Recombination Centers ◽  
Pl Intensity

Photoluminescence (PL) from silicon nanocrystals deposited on top of silica-glass template and from silicon nanocrystals in nc_Si/SiO2 multilayer films were studied as a function of ultraviolet (UV) laser irradiation time in vacuum. Both the films exhibit intense visible PL at room temperature under laser excitation. It was found that upon prolong irradiation time using a He-Cd laser (325 nm) the PL intensity of the films was spectacularly enhanced. The process is reversible and does not happen with excitation wavelength longer than 400 nm. Upon introducing air into the measurement chamber, a rapid decrease of the PL intensity was recorded. This observation suggests that the UV light may lead to modification of nonradiative recombination centers in the films and thus improves the emission yield of silicon nanocrystals.

scholarly journals Evolution Mechanism of Macromolecular Structure in Coal during Heat Treatment: Based on FTIR and XRD In Situ Analysis Techniques

2019 ◽  
Vol 2019 ◽  
pp. 1-18 ◽  
Author(s):  
Dun Wu ◽  
Wenyong Zhang
Keyword(s):  
Heat Treatment ◽  
Infrared Spectroscopy ◽  
Infrared Spectrum ◽  
Functional Groups ◽  
Coal Sample ◽  
Diffraction Peak ◽  
Coal Rank ◽  
Coal Structure ◽  
Temperature Range

Owing to the complexity and heterogeneity of coal during pyrolysis, the ex situ analytical techniques cannot accurately reflect the real coal pyrolysis process. In this study, according to the joint investigation of Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD), the structural evolution characteristics of lignite-subbituminous coal-bituminous coal-anthracite series under heat treatment were discussed in depth. The results of the infrared spectrum of coal show that the different functional groups of coal show different changes with the increase of coal rank before pyrolysis experiment. Based on in situ infrared spectroscopy experiments, it was found that the infrared spectrum curves of the same coal sample have obvious changes at different pyrolysis temperatures. As a whole, when the pyrolysis temperature is between 400 and 500°C, the coal structure can be greatly changed. By fitting the infrared spectrum curve, the infrared spectrum parameters of coal were obtained. With the change of temperature, these parameters show regular changes in coal with different ranks. In the XRD study of coal, the absorption intensity of the diffraction peak (002) of coal increases with increasing coal rank. The XRD patterns of coal have different characteristics at different pyrolysis temperatures. Overall, the area of (002) diffraction peak of the same coal sample increases obviously with the increase of temperature. The XRD structural parameter of coal was obtained by using the curve fitting method. The changing process of two parameters (interlayer spacing (d002) and stacking height (Lc)) can be divided into two main stages, but the average lateral size (La) does not change significantly and remains at the 2.98 ± 0.09 nm. In summary, the above two technologies complement each other in the study of coal structure. The temperature range of both experiments is different, but the XRD parameters of coal with different ranks are reduced within the temperature range of less than 500°C, which reflects that the size of coal-heated aromatic ring lamellae is reduced and the distance between lamellae is also reduced, indicating that the degree of condensation of coal aromatic nuclei may be increased. Correspondingly, the FTIR parameters of coal also reflect that, with increasing temperature, the side chains of coal are constantly cracked, the oxygen-containing functional groups are reduced, and the degree of aromatization of coal may be increased.

Modification of PEDOT:PSS Surface by RGD Peptide

2019 ◽  
Vol 955 ◽  
pp. 68-73
Author(s):  
Šárka Tumová ◽  
Romana Malečková ◽  
Vojtěch Enev ◽  
Stanislav Stříteský ◽  
Jan Víteček ◽  
...  
Keyword(s):  
Contact Angle ◽  
Raman Spectroscopy ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Uv Light ◽  
Coupling Reaction ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Rgd Peptide ◽  
Novel Technique

In this paper, a novel technique for modification of PEDOT:PSS surface by the arginine-glycine-aspartic (RGD) acid, using a bifunctional photolinker sulfosuccinimidyl 6-(4’-azido-2’-nitrophenylamino) hexanoate (sulfo-SANPAH), is presented. The technique is based on the UV light initialized immobilization of the photolinker to the surface of the polymer and subsequent link of the RGD peptide to the photolinker via coupling reaction. The aim of this modification is the improvement of the biocompatibility and hydrophilicity of the polymer PEDOT:PSS. To confirm if the process of conjugation of RGD peptide to the surface of the polymer PEDOT:PSS was successful, the contact angle measurement, Fourier transform infrared spectroscopy, Raman spectroscopy and elemental analysis was performed. All of the obtained results indicate the conjugation of RGD peptide to the PEDOT:PSS surface was successful.

scholarly journals High-Resolution Infrared Spectroscopy of the v1+ v4Band of14NF3:Reductions of the Rovibrational Hamiltonian

2012 ◽  
Vol 9 (1) ◽  
pp. 253-259 ◽  
Author(s):  
Hamid Najib ◽  
Siham Hmimou ◽  
Hicham Msahal
Keyword(s):  
Experimental Data ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Excited State ◽  
High Resolution ◽  
Infrared Spectrum ◽  
Fourier Transform Infrared ◽  
Sixth Order ◽  
Degenerate State ◽  
Unitary Equivalence

The high-resolution Fourier transform infrared spectrum of nitrogen trifluoride NF3has been studied in the v1+ v4perpendicular band region around 1523 cm−1. All experimental data have been refined applying various reduction forms of the effective rovibrational Hamiltonian developed for an isolated degenerate state of a symmetric top molecule. The v1= v4= 1 excited state of the14NF3oblate molecule was treated with models taking into account ℓ- andk-type intravibrational resonances. Parameters up to sixth order have been accurately determined and the unitary equivalence of the derived parameter sets in different reductions was demonstrated.

Near Infrared Spectroscopy

1998 ◽  
Vol 6 (1) ◽  
pp. 3-17 ◽  
Author(s):  
L. Bokobza
Keyword(s):  
Infrared Spectroscopy ◽  
Infrared Spectrum ◽  
Near Infrared Spectroscopy ◽  
Spectral Properties ◽  
Near Infrared ◽  
High Energy ◽  
Local Mode ◽  
Mode Effects ◽  
Vibrational Anharmonicity ◽  
Frequency Intensity

Some of the concepts that make a near infrared spectrum understandable are reviewed. The origin of vibrational anharmonicity which determines the occurrence and the spectral properties (frequency, intensity) is discussed. The importance of the effects of the resonances which increase with increasing excitation are mentioned. Some of the characteristics of high energy overtone/combination spectra are considered in relation to local mode effects. The location of some particular group frequencies is provided.

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