Investigation of chemical transformations of thiophenylglycoside of muramyl dipeptide on the fumed silica surface using TPD-MS, FTIR spectroscopy and ES IT MS

Abstract

In this study, chemical transformations of benzyl ester of О-(phenyl-2-acetamido-2,3-dideoxy-1-thio-β-d-glucopyranoside-3-yl)-d-lactoyl-l-alanyl-d-isoglutamine (SPhMDPOBn) on the fumed silica surface were examined, and the surface complex structure was characterized by temperature-programmed desorption mass spectrometry (TPD-MS), infrared spectroscopy (FTIR) and electrospray ion trap mass spectrometry (ES IT MS). Stages of pyrolysis of SPhMDPOBn in pristine state and on the silica surface have been determined. Probably, hydrogen-bonded complex forms between silanol surface groups and the C = O group of the acetamide moiety NH-(CH3)-C = O…H-O-Si≡. The thermal transformations of such hydrogen-bonded complex result in pyrolysis of SPhMDPOBn immobilized on the silica surface under TPD-MS conditions. The shifts ∆ν of amide I band (measured from 1,626 to 1,639 cm−l for SPhMDPOBn in pristine state) of 33 and 35 cm−l which occurred when SPhMDPOBn was immobilized on the silica surface may be caused by a weakening of the intramolecular hydrogen bonding of the SPhMDPOBn because the interaction with the silica surface as hydrogen bond with silanol groups is weaker than that in associates.

Study on the interaction of Hericium erinaceus mycelium polysaccharides and its degradation products with food additive silica nanoparticles

“…There was a broad weak absorption peak at 3 400–3 000 cm −1 with a lower response value, which was ν hydrogen-bonded silanols (overlapping the stretching modes in hydrogen-bonded hydroxyl bands produced by OH bonds adsorbed water and Si-OH). It showed that there was a small amount of isolated –OH on the surface of nSiO 2 , which helped to form hydrogen bonds between the hydroxyl groups of nSiO 2 and the hydroxyl groups of polysaccharides ( Azizova, Kulik, Palianytsia, Zemlyakov, Tsikalova & Chirva, 2014 ).

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Green Synthesis of Zwitterion-Functionalized Nano-Octahedral Ceria for Enhanced Intracellular Delivery and Cancer Therapy

“…The broad peak in the FTIR spectra at 3400 cm –1 for all three samples (NO, SNO, and FNO) is attributed to the symmetric stretching of the hydroxyl group . The transmittance intensity of this peak was the least for FNO, which suggests the modification of the surface OH groups during functionalization.…”

“…The broad peak in the FTIR spectra at 3400 cm −1 for all three samples (NO, SNO, and FNO) is attributed to the symmetric stretching of the hydroxyl group. 49 The trans-mittance intensity of this peak was the least for FNO, which suggests the modification of the surface OH groups during functionalization. The presence of stretching vibrations for CO, SiO, and SiC at 1720, 900, and 1130 cm −1 , respectively, in SNO and FNO differentiates these materials from NO.…”

“…The presence of stretching vibrations for CO, SiO, and SiC at 1720, 900, and 1130 cm −1 , respectively, in SNO and FNO differentiates these materials from NO. 49 The establishment of silane linkages and oligomers in SNO and FNO, respectively, is shown by the CH stretching peak at 2900 cm −1 in Figure 3a and the Raman spectra in Figure 3b. The correspondence of the peaks (aromatic CC and CC, CN, CS, SO) for FTIR and Raman spectra for the general structure of FNO supports the NMR data for the localized structure of the functionalization agents.…”

Hexagonal Mesoporous Silica‐Supported Copper Oxide (CuO/HMS) Catalyst: Synthesis of Primary Amides from Aldehydes in Aqueous Medium

“…The FTIR spectrum of CuO/HMS shows a broad absorption around 3600–3200 cm −1 ascribed to the overlapping of the O−H stretching of adsorbed water bands and silanols (Figure S3 in the Supporting Information) . The band observed near 1640 cm −1 corresponds to the bending mode of vibration of −OH groups of adsorbed water .…”