FT-IR and Raman spectra vibrational assignments and density functional calculations of 1-naphthyl acetic acid

Abstract Background The atherosclerotic ascending aorta could represent a potential source of emboli or could be an indicator of atherosclerosis in general with high mortality. The mechanism of aneurysm formation and atherosclerosis of the ascending aorta at the molecular level has not yet been clarified. To approach the mechanism of ascending aortic lesions and mineralization at a molecular level, we used the non-destructive FT-IR, Raman spectroscopy, SEM and Hypermicroscope. Methods Six ascending aorta biopsies were obtained from patients who underwent aortic valve replacement (AVR) cardiac surgery. CytoViva (einst inc) hyperspectral microscope was used to obtain the images of ascending aorta. The samples were dissolved in hexane on a microscope glass plate. The FT-IR and Raman spectra were recorded with Nicolet 6700 thermoshintific and micro-Raman Reinshaw (785nm, 145 mwatt), respectively. The architecture of ascending aorta biopsies was obtained by using scanning electron microscope (SEM of Fei Co) without any coating. Results FT-IR and Raman spectra showed changes arising from the increasing of lipophilic environment and aggregate formation (Fig. 1). The band at 1744 cm–1 is attributed to aldehyde CHO mode due to oxidation of lipids. The shifts of the bands of the amide I and amide II bands to lower are associated with protein damage, in agreement with SEM data. The bands at about 1170–1000 cm–1 resulted from the C-O-C of advanced glycation products as result of connecting tissues fragmentations and polymerization. The spectroscopic data were analogous with the lesions observed with SEM and hypermicroscopic images. Conclusions The present innovate molecular structure analysis showed that upon ascending aorta aneurysm development an excess of lipophilic aggregate formation and protein lesions, changing the elasticity of the aorta's wall. The released Ca2+ interacted mostly with carbonate-terminal of cellular protein chains accelerated the ascending aorta calcifications. Figure 1. FT-IR and Raman spectra Funding Acknowledgement Type of funding source: None

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C2: An Asymmetric Specie ?

10.26434/chemrxiv.11913669.v1 ◽

2020 ◽

Author(s):

Robson de Farias

Keyword(s):

Chemical Bond ◽

Raman Spectra ◽

Density Functional ◽

Functional Approach ◽

Ir And Raman Spectra ◽

Basis Set ◽

Ir And Raman

The present work is another contribution to a better understanding of the chemical bond in C2. Several density functional approach/basis set provided calculated IR and Raman spectra with simultaneous active bands. Hence, the hypothesis of electronic asymmetry in C2 [1] was reinforced.

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Chemical adsorption of salicylate on silver - A systematic approach to the interpretation of surface-enhanced vibrational spectra

Canadian Journal of Chemistry ◽

10.1139/v04-075 ◽

2004 ◽

Vol 82 (6) ◽

pp. 987-997 ◽

Cited By ~ 36

Author(s):

P J.G Goulet ◽

R F Aroca

Keyword(s):

Salicylic Acid ◽

Raman Spectra ◽

Vibrational Spectra ◽

Density Functional ◽

Ir And Raman Spectra ◽

Chemical Adsorption ◽

Surface Enhanced ◽

Surface Enhanced Raman ◽

Enhanced Raman Scattering ◽

Ir And Raman

In this work, surface-enhanced vibrational spectroscopy and normal vibrational spectroscopy as well as density functional theory (DFT) computational methods have been employed to investigate the nature of the chemical adsorption and orientation of the surface species generated from salicylic acid at silver surfaces. The structure of salicylic acid and its IR and Raman spectra are determined at the B3LYP/6-311+G(d,p) level of theory. These results are used in the assignment of the vibrational spectra. Surface-enhanced Raman scattering (SERS) spectra obtained from silver island films thinly coated with salicylic acid confirm chemical adsorption on the Ag nanostructures. To probe the nature of this surface complex, the optimized geometries and IR and Raman spectra of two model salicylate-silver complexes (Ag1 and Ag2) were calculated at the B3LYP/Lanl2DZ level of theory. It was found that good agreement exists between experimentally observed SERS spectra and the simulated SERS spectra of a complex with the salicylate monoanion bound to a Ag+ ion through its carboxylate group (Ag1). The carboxylate silver salt of salicylic acid (essentially the Ag1 complex) was also prepared, and its IR and Raman spectra were recorded for comparison with the surface-enhanced vibrational spectra. These results, along with the application of surface selection rules, suggest that salicylic acid is deprotonated at silver surfaces, interacting through its carboxylate group alone, and is preferentially in a tilted head-on orientation.Key words: chemisorption, salicylic acid, silver, density functional theory, surface-enhanced Raman scattering, reflection-absorption IR spectroscopy, surface-enhanced IR absorption.

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