Aromatic and Heteroaromatic Rings

Colthup, Norman B.; Daly, Lawrence H.; Wiberley, Stephen E.

doi:10.1016/b978-0-08-091740-5.50011-9

Cited by 38 publications

(23 citation statements)

References 37 publications

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“…A peak at 1602 cm –1 corresponds to quadrant stretching vibration of CC at all positions. The peak shift from 1630 (tetracene) to 1602 cm –1 (heated tetracene above 853 K) relates to the increment of conjugated system, which is similar to the negative shift of Raman spectra. , The formation of pentagon by dehydrogenation between two tetracene molecules generated similar spectral shape to the experimental DRIFT spectra (Figure d,e). Those structures with pentagons are not main structures above 853 K, but the pentagon should be present.…”

Section: Resultssupporting

confidence: 69%

“…The experimental peak at ca. 1450 cm –1 has been reported to correspond to the characteristic peak for zigzag edges, semicircle ring stretch vibration of PAHs, C–H rock vibration of five-membered ring heterocyclic compounds, , and pentagons in fullerene and other aromatic compounds. , Thus, the peak at 1437 cm –1 observed in this work would correspond to these peaks including pinch mode in the presence of pentagons (Figures d,e and S9) and the presence of zigzag edges, although the peak intensity of zigzag edges was weak (Figures S10 and S11). In addition, the peak at 1437 cm –1 was related to sp 3 C–H (Figures b,c and S7) and dehydrogenated structure between tetracene molecules (Figure S8).…”

Section: Resultsmentioning

confidence: 53%

“…This negative shift from 1620 to 1606 and 1580 cm –1 can be explained by the formation of dehydrogenated structure and graphene-like structure (G band). From the point of view of PAHs, peaks in the region of G and D′ band are known as quadrant stretch rather than G and D′ bands. , This negative shift of the peak of quadrant stretch upon increment of the conjugated system has been reported from the point of view of polyacetylene . Raman spectra of almost all possible dehydrogenated structures of tetracene were calculated, and the selected spectra are shown in Figure S8.…”

Section: Resultsmentioning

confidence: 84%

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Carbon Materials with Zigzag and Armchair Edges

Yamada

Kawai

Yorimitsu

et al. 2018

ACS Appl. Mater. Interfaces

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Carbon materials such as graphene and graphene nanoribbon with zigzag and armchair edges have attracted much attention because of various applications such as electronics, batteries, adsorbents, and catalyst supports. Preparation of carbon materials with different edge structures at a large scale is essential for the future of carbon materials, but it is generally difficult and expensive because of the necessity of organic synthesis on metal substrates. This work demonstrated a simple preparation method of carbon materials with zigzag and armchair edges with/without nonmetallic silica supports from aromatic compounds such as tetracene with zigzag edges and chrysene with armchair edges and also determined the edge structures in detail by three types of analyses such as (1) reactive molecular dynamic simulation with a reactive force field, (2) Raman and infrared (IR) spectra combined with calculation of spectra, and (3) reactivity analyzed by oxidative gasification using thermogravimetric analysis. Two different types of carbon materials with characteristic Raman and IR spectra could be prepared. These carbon materials with different edge structures also clearly showed different tendency in oxidative gasification. This work did not only show the simple preparation method of carbon materials with different edge structures, but also contributes to the development of detailed analyses for carbon materials.

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Section: Resultssupporting

confidence: 69%

Section: Resultsmentioning

confidence: 53%

Section: Resultsmentioning

confidence: 84%

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Carbon Materials with Zigzag and Armchair Edges

Yamada

Kawai

Yorimitsu

et al. 2018

ACS Appl. Mater. Interfaces

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“…Another single antenna with the same dimensions was used to analyze the vibrations of a 4-MTP SAM (Figure b). The red dashed lines indicate the spectral positions of the two most prominent vibrations: the aromatic ring (in the plane) stretches (1594 and 1485 cm –1 ) . The other two vibrational signals in the low-frequency region (i.e., C–O–C stretches at 1287 and 1244 cm –1 ) are not observed in the antenna spectrum because of the very low SEIRA enhancement provided by the antenna at those off-resonant wavelengths.…”

Section: Results and Discussionmentioning

confidence: 99%

Nanogapped Au Antennas for Ultrasensitive Surface-Enhanced Infrared Absorption Spectroscopy

et al. 2017

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Surface-enhanced infrared absorption (SEIRA) spectroscopy has outstanding potential in chemical detection as a complement to surface-enhanced Raman spectroscopy (SERS), yet it has historically lagged well behind SERS in detection sensitivity. Here we report a new ultrasensitive infrared antenna designed to bring SEIRA spectroscopy into the few-molecule detection range. Our antenna consists of a bowtie-shaped Au structure with a sub-3 nm gap, positioned to create a cavity above a reflective substrate. This three-dimensional geometry tightly confines incident mid-infrared radiation into its ultrasmall junction, yielding a hot spot with a theoretical SEIRA enhancement factor of more than 10, which can be designed to span the range of frequencies useful for SEIRA. We quantitatively evaluated the IR detection limit of this antenna design using mixed monolayers of 4-nitrothiophenol (4-NTP) and 4-methoxythiolphenol (4-MTP). The optimized antenna structure allows the detection of as few as ∼500 molecules of 4-NTP and ∼600 molecules of 4-MTP with a standard commercial FTIR spectrometer. This strategy offers a new platform for analyzing the IR vibrations of minute quantities of molecules and lends insight into the ultimate limit of single-molecule SEIRA detection.

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“…It does not seem to be possible to distinguish mono-, di-, or trisubstitution, except possibly for ring CH stretch absorption for mono or disubstitution, which can sometimes be seen in the 3100-3000 cm −1 region. There is usually at least one band in the 1450-1350 cm −1 region [33]. The absorbances of the extraction solutions, obtained in a neutral medium, using distilled water, were determined spectrophotometrically.…”

Section: Structural Modification Studies By Ftirmentioning

confidence: 99%

Photochemical Stability of a Cotton Fabric Surface Dyed with a Reactive Triphenodioxazine Dye

Roşu¹,

Gavat

Roşu³

et al. 2021

Polymers

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The paper describes the photochemical stability of a commercial triphenodioxazine dye (Reactive Blue_204) linked onto a cotton fabric. Preliminary studies have shown that as a result of irradiation, the dye and its photodegradation products can pass directly onto the skin under conditions that mimic human perspiration and cause side-effects. The cotton dyed fabric was photo irradiated at different time intervals. Standard methods were employed to evaluate the color strength at various levels of pH, temperature, dyeing contact time, and salt concentration. The influence of UV radiation at different doses (λ > 300 nm) on the structural and color modifications of the dyed cotton fabrics was studied. Structural modifications before and after irradiation were compared by applying FTIR, UV–Vis, and near infrared chemical imaging (NIR–CI) techniques. Color modifications were investigated with the CIELAB system. Color differences significantly increased with the irradiation dose. High irradiation doses caused changes in the dye structure.

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Aromatic and Heteroaromatic Rings

Cited by 38 publications

References 37 publications

Carbon Materials with Zigzag and Armchair Edges

Carbon Materials with Zigzag and Armchair Edges

Nanogapped Au Antennas for Ultrasensitive Surface-Enhanced Infrared Absorption Spectroscopy

Photochemical Stability of a Cotton Fabric Surface Dyed with a Reactive Triphenodioxazine Dye

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