scholarly journals Synthesis and Phase Transition Behaviours of New Chalcone Derivatives

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
S. T. Ha ◽  
Y. W. Low
Keyword(s):  
Phase Region ◽  
Spectroscopic Techniques ◽  
Organic Solution ◽  
Scanning Calorimetry ◽  
Chalcone Derivatives ◽  
Heating And Cooling ◽  
Phenyl Rings ◽  
Mesomorphic Property ◽  
Dsc Thermograms ◽  
C Nmr

A series of new chalcone derivatives with a general formula of C11H27COOC6H4COCH=CHC6H4X where X=F, Cl, Br, and NO2were well synthesized and crystallized from organic solution. The physical properties as well as the chemical formulations of these compounds were determined by spectroscopic techniques (FTIR, and1H and13C NMR). Differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) techniques were employed to study their transition temperatures and mesophase characteristics. DSC thermograms of compounds with fluoro and nitro substituents displayed direct isotropization and recrystallization during heating and cooling processes. Chloro and bromo analogues exhibited Cr1-to-Cr2transition within the crystal phase region. It was also found that enone linkage showed fewer tendencies to exhibit mesomorphic property compared to imine linkage. However, when enone linkage is combined with other central linkages and additional phenyl rings, it turns conducive to mesomorphism.

scholarly journals New Homologues Series of Heterocyclic Schiff Base Ester: Synthesis and Characterization

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Yee-Ting Chong ◽  
Norazilawati Muhamad Sarih ◽  
Sie-Tiong Ha ◽  
Md. Rezaul Karim Sheikh
Keyword(s):  
Schiff Base ◽  
Relative Phase ◽  
Structural Information ◽  
Optical Microscope ◽  
Spectroscopic Techniques ◽  
Ester Synthesis ◽  
Scanning Calorimetry ◽  
Smectic C ◽  
Heating And Cooling ◽  
C Nmr

A homologous series of liquid crystal bearing with heterocyclic thiophene Schiff base ester with alkanoyloxy chain (CH3(CH2)nCOO–, where n=4, 6, 8, 10, 12, 14, 16) was successfully synthesized through the modification of some reported methods. The structural information of these compounds was isolated and characterized through some spectroscopic techniques, such as FTIR, 1H, and 13C NMR and elemental analysis. Textural observation was carried out using a polarizing optical microscope (POM) over heating and cooling cycles. It was found that all synthesized compounds (3a–g) exhibited an enantiotropic nematic phase upon the heating and cooling cycle with high thermal stability. Moreover, a characteristic bar transition texture was observed for compounds 3f and 3g which have shown transition of nematic-to-smectic C phase. This has been further confirmed by obtaining relative phase transition temperature using the differential scanning calorimetry (DSC).

scholarly journals Influence of Linking Group Orientation on Mesomorphism of Two Aromatic Ring Mesogens

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
L. K. Ong ◽  
S. T. Ha
Keyword(s):  
Isotropic Phase ◽  
Scanning Calorimetry ◽  
Polarizing Microscopy ◽  
Group Orientation ◽  
Heating And Cooling ◽  
Ester Linkage ◽  
Microscopy Techniques ◽  
Optical Polarizing Microscopy ◽  
Mesomorphic Properties ◽  
Dsc Thermograms

A new homologous series of alkyl 4-{[(4-chlorophenyl)imino]methyl}benzoates were prepared, and all the members are differentiate by the alkoxy chain length,CnH2n+1O, wheren=2–7, 9, 11, 13, 15. Their phase transition behaviors and mesophase characteristics were studied by differential scanning calorimetry (DSC) and optical polarizing microscopy techniques. DSC thermograms show direct isotropization and recrystallization during heating and cooling processes, respectively. The crystal phase changed directly to dark area textures (isotropic phase) without displaying any mesophase. The mesomorphic properties of compounds studied are strongly dependent on the orientation of the ester linkage. Reversed ester linkage has caused depression of mesomorphic property in the compounds studied.

Synthesis, Electrochemical, and Thermal Properties of [3]Ferrocenophane-Containing Chalcone Derivatives

2015 ◽  
Vol 68 (7) ◽  
pp. 1035 ◽  
Author(s):  
Haiying Zhao ◽  
Xueyou Zhu ◽  
Dong Wang ◽  
Shufeng Chen ◽  
Zhanxi Bian
Keyword(s):  
Differential Scanning Calorimetry ◽  
Thermal Properties ◽  
Phase Transitions ◽  
Optical Microscopy ◽  
Alkyl Chain ◽  
Freezing Process ◽  
Naphthalene Ring ◽  
Scanning Calorimetry ◽  
Chalcone Derivatives ◽  
Heating And Cooling

[3]Ferrocenophane-containing chalcone derivatives with benzene ring (3a–3d) or naphthalene ring (3e–3f) were synthesized and characterized. The potentials for [3]ferrocenophane-containing chalcones cathodically shifted ~70–80 mV compared with those of ferrocene-containing chalcones, indicating easier oxidation by loss of an electron for the former. The thermal behaviours of the prepared compounds were studied by differential scanning calorimetry and polarizing optical microscopy. Compound 3f with terminal alkyl chain of 14 carbon atoms displayed mesophases, whereas other compounds were non-mesomorphic and showed either crystal polymorphic phase transitions or simple melting and freezing process in the heating and cooling cycles.

Chalcones: As potent α-amylase enzyme inhibitors; synthesis, in vitro, and in silico studies

2020 ◽  
Vol 16 ◽  
Author(s):  
Mahboob Ali ◽  
Momin Khan ◽  
Khair Zaman ◽  
Abdul Wadood ◽  
Maryam Iqbal ◽  
...  
Keyword(s):  
In Silico ◽  
Enzyme Inhibitors ◽  
Biological Activities ◽  
Condensation Reaction ◽  
Type Ii Diabetes Mellitus ◽  
Spectroscopic Techniques ◽  
Chalcone Derivatives ◽  
In Silico Studies ◽  
Wide Range

: Background: The inhibition of α-amylase enzyme is one of the best therapeutic approach for the management of type II diabetes mellitus. Chalcone possesses a wide range of biological activities. Objective: In the current study chalcone derivatives (1-17) were synthesized and evaluated their inhibitory potential against α-amylase enzyme. Method: For that purpose, a library of substituted (E)-1-(naphthalene-2-yl)-3-phenylprop-2-en-1-ones was synthesized by ClaisenSchmidt condensation reaction of 2-acetonaphthanone and substituted aryl benzaldehyde in the presence of base and characterized via different spectroscopic techniques such as EI-MS, HREI-MS, 1H-, and 13C-NMR. Results: Sixteen synthetic chalcones were evaluated for in vitro porcine pancreatic α-amylase inhibition. All the chalcones demonstrated good inhibitory activities in the range of IC50 = 1.25 ± 1.05 to 2.40 ± 0.09 μM as compared to the standard commercial drug acarbose (IC50 = 1.34 ± 0.3 μM). Conclusion: Chalcone derivatives (1-17) were synthesized, characterized, and evaluated for their α-amylase inhibition. SAR revealed that electron donating groups in the phenyl ring have more influence on enzyme inhibition. However, to insight the participation of different substituents in the chalcones on the binding interactions with the α-amylase enzyme, in silico (computer simulation) molecular modeling analyses were carried out.

scholarly journals pH-controlled synthesis of sustainable lauric acid/SiO2 phase change material for scalable thermal energy storage

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shafiq Ishak ◽  
Soumen Mandal ◽  
Han-Seung Lee ◽  
Jitendra Kumar Singh
Keyword(s):  
Electron Microscopy ◽  
Phase Change ◽  
Lauric Acid ◽  
Photoelectron Spectroscopy ◽  
Phase Change Materials ◽  
Precursor Solution ◽  
Thermal Reliability ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Heating And Cooling

AbstractLauric acid (LA) has been recommended as economic, eco-friendly, and commercially viable materials to be used as phase change materials (PCMs). Nevertheless, there is lack of optimized parameters to produce microencapsulated PCMs with good performance. In this study, different amounts of LA have been chosen as core materials while tetraethyl orthosilicate (TEOS) as the precursor solution to form silicon dioxide (SiO2) shell. The pH of precursor solution was kept at 2.5 for all composition of microencapsulated LA. The synthesized microencapsulated LA/SiO2 has been characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). The SEM and TEM confirm the microencapsulation of LA with SiO2. Thermogravimetric analysis (TGA) revealed better thermal stability of microencapsulated LA/SiO2 compared to pure LA. PCM with 50% LA i.e. LAPC-6 exhibited the highest encapsulation efficiency (96.50%) and encapsulation ratio (96.15%) through Differential scanning calorimetry (DSC) as well as good thermal reliability even after 30th cycle of heating and cooling process.

scholarly journals Li-Nafion Membrane Plasticised with Ethylene Carbonate/Sulfolane: Influence of Mixing Temperature on the Physicochemical Properties

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1150
Author(s):  
Aigul S. Istomina ◽  
Tatyana V. Yaroslavtseva ◽  
Olga G. Reznitskikh ◽  
Ruslan R. Kayumov ◽  
Lyubov V. Shmygleva ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Ethylene Carbonate ◽  
Membrane Integrity ◽  
Amorphous Structure ◽  
Nafion Membrane ◽  
Polymer Gel ◽  
Scanning Calorimetry ◽  
Practical Applications ◽  
Heating And Cooling ◽  
Solvent Uptake

The use of dipolar aprotic solvents to swell lithiated Nafion ionomer membranes simultaneously serving as electrolyte and separator is of great interest for lithium battery applications. This work attempts to gain an insight into the physicochemical nature of a Li-Nafion ionomer material whose phase-separated nanostructure has been enhanced with a binary plasticiser comprising non-volatile high-boiling ethylene carbonate (EC) and sulfolane (SL). Gravimetric studies evaluating the influence both of mixing temperature (25 to 80 °C) and plasticiser composition (EC/SL ratio) on the solvent uptake of Li-Nafion revealed a hysteresis between heating and cooling modes. Differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) revealed that the saturation of a Nafion membrane with such a plasticiser led to a re-organisation of its amorphous structure, with crystalline regions remaining practically unchanged. Regardless of mixing temperature, the preservation of crystallites upon swelling is critical due to ionomer crosslinking provided by crystalline regions, which ensures membrane integrity even at very high solvent uptake (≈200% at a mixing temperature of 80 °C). The physicochemical properties of a swollen membrane have much in common with those of a chemically crosslinked polymer gel. The conductivity of ≈10−4 S cm−1 demonstrated by Li-Nafion membranes saturated with EC/SL at room temperature is promising for various practical applications.

scholarly journals Competitive Diels–Alder and ene addition of N-arylmaleimides to 7-dehydrocholesteryl acetate

1992 ◽  
Vol 70 (11) ◽  
pp. 2730-2744 ◽  
Author(s):  
William J. Leigh ◽  
Donald W. Hughes ◽  
D. Scott Mitchell
Keyword(s):  
Molecular Mechanics ◽  
Nmr Spectra ◽  
Benzene Solution ◽  
Diels Alder ◽  
Spectroscopic Techniques ◽  
Two Dimensional ◽  
A Minor ◽  
C Nmr ◽  
Alder Adduct ◽  
Ene Addition

Thermolysis of N-phenyl, N-para-biphenyl, and N-para, para′-terphenylmaleimide with 7-dehydrocholesteryl acetate in benzene solution at 200 °C yields mixtures of four cycloadducts in relative yields that are essentially independent of the maleimide substituent. The three major products are those of ene addition to C7 of the steroid with abstraction of the proton at C9 or C14. The α-endo-Diels-Alder adduct is formed as a minor product. The structures of the adducts have been elucidated on the basis of one- and two-dimensional 1H and 13C NMR spectroscopic techniques, including homonuclear 1H decoupling, NOE, 1H–1H COSY, heteronuclear 1H–13C shift correlation, and TOCSY 2-D experiments, and the results of molecular mechanics (MMX) calculations. The combination of these techniques has made it possible to almost completely assign the 1H and 13C NMR spectra for two of the ene adducts and the Diels–Alder adduct from reaction of 7-dehydrocholesteryl acetate with N-phenyl maleimide.

Thermotropic behavior of sodium cholesteryl carbonate

2009 ◽  
Vol 24 (1) ◽  
pp. 156-163 ◽  
Author(s):  
Rabkwan Chuealee ◽  
Timothy S. Wiedmann ◽  
Teerapol Srichana
Keyword(s):  
Phase Behavior ◽  
Chemical Structure ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Wave Number ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
X Ray Scattering ◽  
C Nmr

Sodium cholesteryl carbonate ester (SCC) was synthesized, and its phase behavior was studied. The chemical structure was assessed by solid-state infrared spectroscopy based on vibration analysis. The wave number at 1705 and 1276 cm−1 corresponds to a carbonyl carbonate and O–C–O stretching of SCC, respectively. Molecular structure of SCC was further investigated with 1H and 13C NMR spectroscopy. The chemical shift, for the carbonyl carbonate resonance appeared at 155.5 ppm. A molecular mass of SCC was at m/z of 452. Differential scanning calorimetry (DSC), video-enhanced microscopy (VEM) together with polarized light microscopy, and small-angle x-ray scattering (SAXS) were used to characterize the phase behavior as a function of temperature of SCC. Liquid crystalline phase was formed with SCC. Based on the thermal properties and x-ray diffraction, it appears that SCC forms a structure analogous to the type II monolayer structure observed with cholesterol esters.

scholarly journals A STUDY OF PARAMETERS RELATED TO ANALYSIS OF TRANSITION TEMPERATURES AND ENTHALPIES OF POLYPROPYLENE BY DIFFERENTIAL SCANNING CALORIMETRY (DSC)

2002 ◽  
Vol 10 (11) ◽  
pp. 73-78
Author(s):  
Carlos R. Wolf ◽  
Emir Grave
Keyword(s):  
Differential Scanning Calorimetry ◽  
Material Characterization ◽  
Transition Temperatures ◽  
Nitrogen Flow ◽  
Thermoplastic Polymer ◽  
Scanning Calorimetry ◽  
Know How ◽  
Heating And Cooling ◽  
Polypropylene Material ◽  
Dsc Method

Polypropylene is a thermoplastic polymer, widely employed by converter industries to produce different plastic objects. In order to control and optimize the final properties of the polypropylene material, the evaluation of transition temperatures and enthalpies by Differential Scanning Calorimetry (DSC) has a very important role. Therefore, it is fundamental to know how the analytical conditions influence the results. In this study heating and cooling rates, 10°C/min and 20°C/min, and two different rates of nitrogen flow, 20mL/min and 50mL/min were investigated. It was concluded that thermal properties are influenced by rates of heating and rates of nitrogen flow. The best precision was obtained with the low heating rate, 10°C/min, and high flow rate, 50mL/min. These conditions are being used with the DSC method for polyolefin quality control and material characterization.

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