Amide bands in the IR spectra of urethanes

Сучкова, Г. Г.; Maklakov, L. I.

doi:10.1016/j.vibspec.2009.09.002

Cited by 62 publications

(38 citation statements)

References 21 publications

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“…Several characteristic bands were observed at 30°C; 3340 cm -1 for amide A (m (N-H)), 1693 cm -1 for amide I (m(C=O)), 1537 cm -1 for amide II (d (N-H), m(C-N)), 1264 cm -1 for amide III (d (N-H), m(C=O), m(C-N)), 1195 and 1053 cm -1 for urethane (m(C-N), m(C=O), d(C-O-C)). These frequency values were similar within the frequency difference of 1-4 cm -1 to those of a crystal HDC reported by Suchkova and Maklakov [24]. Upon heating the sample in N 2 flow to 200°C, blue or red shifts occurred in these amide bands (blue: amide A and amide I, red: amide II and amide III).…”

Section: Plausible Reaction Mechanism For Zno-catalyzed Hdc Decomposisupporting

confidence: 89%

Phosgene-free decomposition of dimethylhexane-1,6-dicarbamate over ZnO

et al. 2015

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In catalytic decomposition of dimethylhexane-1,6-dicarbamate (HDC) into hexamethylene-1,6-diisocyanate (HDI), Zn-containing homogeneous (i.e., zinc acetate) and heterogeneous (i.e., ZnO) catalysts were active among a number of catalysts tested, due to the great electron withdrawing ability of Zn ions. Particularly, when polyethylene glycol dimethyl ether was used as a solvent, ZnO was found to be relatively robust, because the catalytic performance was maintained up to the third use (HDC conversion of 93 % and HDI yield of 67 % at 180°C for 1 h). Through investigation of a HDC/ZnO mixture at elevated temperatures by IR spectroscopy, a possible reaction scheme of ZnO-catalyzed decomposition of HDC was proposed. The H atom is removed from the N-H group of HDC by hydrogen bonding with an O site on the ZnO surface, followed by coordination of an O-C=O group in monodentate mode to a Zn site. The C-O group in the O-C=O linkage is then cleaved yielding the isocyanate and surface methoxide species. Finally, methanol is released from ZnO by a reaction between the surface methoxide and the hydroxyl species.

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Section: Plausible Reaction Mechanism For Zno-catalyzed Hdc Decomposisupporting

confidence: 89%

Phosgene-free decomposition of dimethylhexane-1,6-dicarbamate over ZnO

et al. 2015

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“…The 1410 cm -1 band results from the stretch vibrations of -OH groups, which are located at the surface of SiO 2 nanoparticles. The 380 cm -1 band corresponds to the deformations of the urethane groups [14]. Comparison of the Raman spectra of monomer and polymer -AuNP nanocomposites shows, that under the influence of 522 nm irradiation the concentration of SiO 2 surface-connected -OH groups and the mobility of urethane framework decrease.…”

Section: Results and Discussion Of Holographic Recording Of Pcs In Acmentioning

confidence: 98%

Peculiarities of photonic crystal recording in functional polymer nanocomposites by multibeam interference holography

Zhuk

Burunkova

Denisyuk

et al. 2017

Polymer

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Two-dimensional photonic crystal structures (PCS) were fabricated using a one-step recording process, multi-beam interference in smart polymer nanocomposites incorporating SiO2 and Au nanoparticles sensitized to 532 nm laser radiation. It was shown, that PCS with different geometry can be recorded in thick nanocomposite layers. The typical two dimensional (2D) PCS have square structure with 2-8 µm period, being in good agreement with theoretical structures obtained by mathematical modeling of the recorded PCS. The peculiarities of the photo-polymerization of nanocomposites with plasmonic Au nanoparticles were analyzed on the basis of Surface Plasmon Resonance Imaging (SPRi) and Raman spectroscopy investigations and used for the interpretation of the recording process and periodic structure formation. Abstract Two-dimensional photonic crystal structures (PCS) were fabricated using a one-step recording process, multi-beam interference in smart polymer nanocomposites incorporating SiO 2 and Au nanoparticles sensitized to 532 nm laser radiation. It was shown, that PCS with different geometry can be recorded in thick nanocomposite layers. The typical two dimensional (2D) PCS have square structure with 2-8 µm period, being in good agreement with theoretical structures obtained by mathematical modeling of the recorded PCS. The peculiarities of the photopolymerization of nanocomposites with plasmonic Au nanoparticles were analyzed on the basis of Surface Plasmon Resonance Imaging (SPRi) and Raman spectroscopy investigations and used for the interpretation of the recording process and periodic structure formation.

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“…In (thio)amide compounds several infrared absorption bands which are called ''(thio)amide bands'' are important for studying structural and electronic properties because they are sensitive to intermolecular hydrogen bonding and conformational changes [29,30]. The thioamide bands I, II, III and IV have a large contribution from d(NAH) (I), m(CAN) (II and III) and m(C@S) (IV) motions and are usually reported around 1500, 1300, 1100 and 750 cm À1 , respectively [31,32].…”

Section: Vibrational Analysismentioning

confidence: 99%