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Analytic Methods fo the Bioactive Compounds in Waste
Published in Quan V. Vuong, Utilisation of Bioactive Compounds from Agricultural and Food Waste, 2017
Heteronuclear correlations can also be viewed in 2D NMR. This is a very important diagnostic tool in determining the structure of an unknown compound as it is able to show which hydrogen atoms are attached to which carbons atoms within the organic scaffold. Running a Heteronuclear Single Quantum Coherence (HSQC) experiment indicates the presence of all one bond coupling between 1H and 13C nuclei within the scaffold. In HSQC spectra, the 1H and 13C spectra are placed on orthogonal axes, with the presence of any contours at the intersection of a 1H signal and a 13C signal indicating that those nuclei are joined through a chemical bond. An example of a HSQC spectrum is shown below in Fig. 20 (Williams and Fleming 1995).
Nuclear Magnetic Resonance
Published in Grinberg Nelu, Rodriguez Sonia, Ewing’s Analytical Instrumentation Handbook, Fourth Edition, 2019
The HMQC (heteronuclear multiple-quantum correlation spectroscopy), HSQC (heteronuclear single-quantum correlation spectroscopy), and HMBC (heteronuclear multiple-bond correlation spectroscopy) are indirect/inverse NMR experiments that correlate 1H with an X nucleus where 1H is the observed nucleus [49, 50]. The 2D homonuclear and heteronuclear correlation experiments can be used to provide definitive structure assignment.
Synthesis and mesomorphism behaviour of chalcones and pyrazoles type compounds as photo-luminescent materials
Published in Liquid Crystals, 2018
Ahmed Jasim M. Al-Karawi, Ali Jasim Hammood, Adil A. Awad, Al-Ameen Bariz OmarAli, Saba Riad Khudhaier, Dhafir T. A. Al- Heetimi, Samer Ghanim Majeed
Elemental analyses (C, H and N) were performed on a EuroEA 3000 Elemental Analyser, while Ag was determined using a 7300 V ICP-OES PerkinElmer-Optima Spectrometer. Electronic spectra (200–1100 nm) of the prepared compounds (5 × 10–5 M of the samples in dichloromethane) were measured at room temperature (RT) using a Varin Cary 100 Conc. spectrophotometer. RF-6000 Shimadzu spectrofluorimeter equipped with a ThermoNeslab RTE7 bath was used to record the fluorescence emissions of the compounds in the solid state. Fourier-transform infrared (FTIR) spectra were obtained in the region (4000–600 cm−1) by using a 8400S-FT-IR Shimadzu spectrophotometer. Nuclear magnetic resonance (1HNMR, 13CNMR, 2D 1H-1H-COSY and 2D 1H-13C-HSQC) spectra were recorded in CDCl3 using a Brucker 400 MHz spectrometer. Mass spectra were carried out using Orbitrap LTQ XL Thermo Fisher scientific mass spectrometer. Differential scanning calorimetry (DSC) thermograms were performed in a nitrogen atmosphere at a heating and cooling rate of 5.0°C/min, using a Linseis STA PT-1000 equipment, which is precalibrated. The equipment was provided with an autocool system. Liquid crystalline mesophases of the compounds were obtained by PW-BK5000R microscope equipped with HS-400 (KER3100-08S) heating stage. XRD-6000 Shimadzu x-ray diffractometer equipped with a Anton Paar HTK1200 heating stage was used to perform the X-ray powder diffraction (XRD) diffractograms at variable temperature, using Cu-Ka radiation (λ = 1.54178 Å). Molar conductivity of silver(I) complexes (1 × 10–3 M in acetone) were recorded at 25°C using a WTW 82362-Weilheim digital conductometer.
Structural characterization of lignin from D. sinicus by FTIR and NMR techniques
Published in Green Chemistry Letters and Reviews, 2019
Zhengjun Shi, Gaofeng Xu, Jia Deng, Mengyao Dong, Vignesh Murugadoss, Chuntai Liu, Qian Shao, Shide Wu, Zhanhu Guo
For an in-depth structural characterization of lignin polymer present in the bamboo species, the milled wood lignin (MWL) of bamboo (D. sinicus) was isolated under a mild condition according to the recognized method of Björkman (10). The structural characteristics of the isolated bamboo lignin were investigated by Fourier transform infrared (FT-IR) and nuclear magnetic resonance (13C NMR and HSQC NMR) spectroscopy in detail.
Liquid crystal and photoluminescent properties of a series of symmetrical 1,2-bis(4-alkoxybenzylidene)hydrazines bearing long-tails of hydrocarbon chain
Published in Liquid Crystals, 2021
Ahmed Jasim M. Al-Karawi, Al-Ameen Bariz OmarAli, Adil A. Awad, Giscard Doungmo, Huayna Terraschke
Different techniques like infrared (IR), ultraviolet-visible (UV–Vis), nuclear magnetic resonance (1HNMR, 13CNMR, DEPT NMR, 2D 1 H-1 H-COSY and 2D 1 H-13C- HSQC) in addition to elemental analysis (CHN) were used to characterise and identify the structure of the prepared compounds (1a–i) and (2a–i).