scholarly journals Spectral Studies on Impact of Alkali Perchlorate (Li/Na/K-ClO4) Salts on the Properties of PVA-Ag-Cr3+ Polymer Nanocomposite Films

2021 ◽  
Vol 2070 (1) ◽  
pp. 012077
Author(s):  
M Hemalatha ◽  
V Krishna Vinay ◽  
D Siva Raju ◽  
Ch Linga Raju
Keyword(s):  
Polymer Films ◽  
Polymer Nanocomposite ◽  
Intramolecular Hydrogen Bonding ◽  
Nanocomposite Films ◽  
Degree Of Crystallinity ◽  
Spectral Studies ◽  
Poly Vinyl Alcohol ◽  
X Ray Diffraction ◽  
Intramolecular Hydrogen ◽  
Metal Nanocomposites

Abstract Poly (Vinyl alcohol) metal (PVA-Ag-Cr) nanocomposites were prepared by a slow evaporation method with the help of a refluxing procedure. The effect of alkali perchlorate (Li/Na/K-QlO4) salts embedded in PVA-metal nanocomposites were analysed with SEM, XRD, EPR, and optical techniques. The surface structure and topology of the synthesized composites were studied using scanning electron microscopy. The crystallinity of the prepared polymer films has been determined using the X-ray diffraction pattern. Existing changes in some diffraction angle with the alkali salts results the fluctuations in the degree of crystallinity. EPR studies reveal the ‘g’ values at 1.96, 1.93, and 1.98 due to the oxidation exchange-coupled pair. The observed absorption spectra of Cr3+ ions corresponding to Li, Na & KClO4 salts in PVAAgSe polymer films revealed the band positions centered at 220, 275, 480, 535, and 1030 nm of all the alkali chlorates with small shifting in-band positions. This may be due to the inter/intramolecular hydrogen bonding.

scholarly journals Synthesis of Silver Nanoparticles from Mimusops elengi Extract of Raw Fruits and Characterization of PVA-Silver Polymer Nanocomposite Films

2021 ◽  
Vol 33 (4) ◽  
pp. 762-766
Author(s):  
BHABANI SHANKAR PANDA ◽  
MOHAMMED ANSAR AHEMAD
Keyword(s):  
Silver Nanoparticles ◽  
Vinyl Alcohol ◽  
Thermal Studies ◽  
Polymer Nanocomposite ◽  
Nanocomposite Films ◽  
Poly Vinyl Alcohol ◽  
X Ray Diffraction ◽  
X Ray ◽  
Uv Visible ◽  
Mimusops Elengi

The present work concerns on the synthesis of silver nanoparticles at 25 ºC using raw fruits extract of Bakul (Mimusops elengi) tree via chemical reduction route development of poly(vinyl alcohol) PVA-silver polymer nanocomposite films. The nanocomposite films were subjected to characterization by UV-visible, FTIR, X-ray diffraction, field emission scanning electron microscope (FESEM) and thermal studies. The UV-visible spectrum shows a characteristic broad absorption band observed near 465 nm suggesting presence of silver nanoparticles in polymer nanocomposites (PNCs) film. The vibrational band shift of –OH group of poly(vinyl alcohol) in the presence of nanoparticle designated the chemical interaction between –OH group of poly(vinyl alcohol) and silver nanoparticles. The FESEM study confirmed that PVA is not only acted as a capping agent, but also a cross-linking agent. X-ray diffraction study shows that the existence of AgNPs in the poly nanocomposite film and nanoaparticles are crystalline in nature. Thermal studies suggest that the enhanced thermal stability is because of the good packing of the polar crystallites in β-PVA composites as compared to the non-polar α-phase of neat poly(vinyl alcohol) (PVA).

Structural and Spectral Studies of Palladium (II) Complexes of Pyridil bis{3-Piperidyl-, bis{Hexamethyleneiminyl-, bis{N(4)-Diethyl- and bis{N(4)-Dipropylthiosemicarbazone}

2000 ◽  
Vol 55 (9) ◽  
pp. 863-870 ◽  
Author(s):  
Alfonso Castiñeiras ◽  
Maria Gil ◽  
Elena Bermejo ◽  
Douglas X. West
Keyword(s):  
Hydrogen Bonding ◽  
Nmr Spectroscopy ◽  
Intramolecular Hydrogen Bonding ◽  
Isomeric Form ◽  
Spectral Studies ◽  
Imine Nitrogen ◽  
Pyridine Nitrogen ◽  
Square Planar ◽  
Intramolecular Hydrogen ◽  
C Nmr

Pyridil bis{N(4)-substituted thiosemicarbazones}, in which the substituents replacing the NH2 group on the thiosemicarbazone moieties are piperidyl, H2Plpip; hexamethyleneiminyl, H2Plhexim; diethylamino, H2Pl4DE; and dipropylamino, H2PI4 DP, have been synthesized. Representative palladium(II) complexes of these bis (thiosemicarbazones) have been characterized by IR, electronic, mass, and 1H and 13C NMR spectroscopy. Crystal structures have been determined for H2Plhexim and two of its palladium(II) complexes. H2Plhexim is in the Z isomeric form with intramolecular hydrogen bonding from both thiosemicarbazone moieties to pyridine nitrogens. [Pd(Plhexim)] has square-planar N2S2 coordination (i.e., imine nitrogen and thiolato sulfur atoms). [Pd2 (Plhexim)Cl2 · DMSO has two PdNNSCl centers with the pyridine nitrogen, imine nitrogen or hydrazinic nitrogen and thiolato sulfur atoms coordinated

Preparation and Crystal Structure of the Potentially Tridentate Substituted Phenoxyacetic Acid (2-Benzoyl-5-methoxyphenoxy)acetic Acid and Its Complex Adduct With Sodium

1995 ◽  
Vol 48 (4) ◽  
pp. 869 ◽  
Author(s):  
G Smith ◽  
EJ Oreilly ◽  
SA See ◽  
KA Byriel ◽  
CHL Kennard
Keyword(s):  
Crystal Structure ◽  
Acetic Acid ◽  
Carboxy Group ◽  
Intramolecular Hydrogen Bonding ◽  
Ligand Molecule ◽  
Phenoxyacetic Acid ◽  
X Ray Diffraction ◽  
X Ray ◽  
Intramolecular Hydrogen ◽  
Hydrogen Bonded

The ring-substituted phenoxyacetic acid (2-benzoyl-5-methoxyphenoxy)acetic acid (HL) (3) and its complex adduct dimer (4) with sodium, [Na2(L)2(HL)2].2HL, have been synthesized and their structures determined by X-ray diffraction. The acid (3) does not have the usual cyclic hydrogen-bonded dimer association, but instead has three-centre intramolecular hydrogen bonding between the carboxyl proton and both the ether and keto oxygens [O---O, 2.602(3), 2.711(3) Ǻ respectively]. Each sodium in the centrosymmetric complex dimer (4) is seven-coordinate [Na-O, 2.313(5)-2.612(5) Ǻ], involving the 'inner' three oxygens of both a protonated and an ionic ligand molecule. In addition, one of these carboxyl oxygens forms a bridge to the inversion-related sodium, while the uncoordinated carboxyl oxygen is hydrogen-bonded to a protonated carboxy group [O---O, 2.464(8) Ǻ]. The molecules of the lattice acid have only one hydrogen-bonded association with the second uncoordinated carboxy group in the dimer [O---O, 2.513(7) Ǻ].

Crystal structures and conformations of 1-α-D-xylofuranosylcytosine and its protonated form (HCl salt)

1981 ◽  
Vol 59 (2) ◽  
pp. 238-245 ◽  
Author(s):  
Michael L. Post ◽  
Carol P. Huber ◽  
George I. Birnbaum ◽  
David Shugar
Keyword(s):  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Direct Method ◽  
Intramolecular Hydrogen Bonding ◽  
Protonated Form ◽  
X Ray Diffraction ◽  
Base Stacking ◽  
Torsion Angles ◽  
Cell Parameters ◽  
Intramolecular Hydrogen

The structures of 1-α-D-xylofuranosylcytosine, C9H13N3O5 (1), and its hydrochloride salt, C9H13N3O5•HCl (1•HCl), have been determined by X-ray diffraction from diffractometer data, using direct method techniques. Both compounds crystallize in the orthorhombic system with Z = 4. Space group and cell parameters are, for 1: P21212, a = 18.706, b = 8.127, c = 7.007 Å; and for 1 HCl::P21212, a = 16.800, b = 8.045, c = 8.897 Å. Refinement by block-diagonal least-squares calculations gave a final R of 0.033 on 873 reflections and 0.034 on 914 reflections for 1 and 1 HCl, respectively. The glycosyl torsion angles are in the anti domain, χCN = −25.1° (1) and −28.6° (1•HC1), and the sugar puckers are nearly pure [Formula: see text] and 3E (1•HCl) forms. The C(4′)—C(5′) rotamer is trans–gauche in both cases. No intramolecular hydrogen bonding occurs in the xylofuranosyl rings. Lattice packing in the crystal structures occurs via intermolecular hydrogen bonding, with base stacking in pairs about one of the 2-fold axes for the neutral form, and with no base-stacking interactions for the protonated form. The biological implications of the structure and conformation of α-nucleosides are examined.

scholarly journals Direct Measurement of Temperature Diffusivity of Nanocellulose-Doped Biodegradable Composite Films

Micromachines ◽  
2020 ◽  
Vol 11 (8) ◽  
pp. 738 ◽  
Author(s):  
Hiroki Fujisawa ◽  
Meguya Ryu ◽  
Stefan Lundgaard ◽  
Denver P. Linklater ◽  
Elena P. Ivanova ◽  
...  
Keyword(s):  
Thermal Properties ◽  
Direct Measurement ◽  
Cross Sections ◽  
Polymer Films ◽  
Composite Films ◽  
Polymer Nanocomposite ◽  
Optical Transmittance ◽  
Nanocomposite Films ◽  
Contact Method ◽  
Resistance Change

The thermal properties of novel nanomaterials play a significant role in determining the performance of the material in technological applications. Herein, direct measurement of the temperature diffusivity of nanocellulose-doped starch–polyurethane nanocomposite films was carried out by the micro-contact method. Polymer films containing up to 2 wt%. of nanocellulose were synthesised by a simple chemical process and are biodegradable. Films of a high optical transmittance T≈80% (for a 200 μm thick film), which were up to 44% crystalline, were characterised. Two different modalities of temperature diffusivity based on (1) a resistance change and (2) micro-thermocouple detected voltage modulation caused by the heat wave, were used for the polymer films with cross sections of ∼100 μm thickness. Twice different in-plane α‖ and out-of-plane α⊥ temperature diffusivities were directly determined with high fidelity: α‖=2.12×10−7 m2/s and α⊥=1.13×10−7 m2/s. This work provides an example of a direct contact measurement of thermal properties of nanocellulose composite biodegradable polymer films. The thermal diffusivity, which is usually high in strongly interconnected networks and crystals, was investigated for the first time in this polymer nanocomposite.

Syntheses and structural studies of η5-pentamethylcyclopentadienyl rhodium(III) and iridium(III) complexes of a Schiff-base expanded porphyrin

2010 ◽  
Vol 14 (01) ◽  
pp. 41-46 ◽  
Author(s):  
Luciano Cuesta ◽  
Vincent M. Lynch ◽  
Jonathan L. Sessler
Keyword(s):  
Schiff Base ◽  
Intramolecular Hydrogen Bonding ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
Coordination Environment ◽  
Metal Centers ◽  
X Ray ◽  
Hydrogen Bonding Interactions ◽  
Intramolecular Hydrogen ◽  
Expanded Porphyrin

Reported here is the synthesis of new binuclear rhodium(III) and iridium(III) semi-sandwich complexes of a Schiff-base expanded porphyrin. Single crystals of these new complexes were subject to X-ray diffraction analysis. The resulting structures revealed that the Schiff-base macrocycle adopts a V-shape in which two {(η5- C 5 Me 5) MCl } ( M = Rh and Ir ) fragments are accommodated within the macrocyclic pocket. The coordination environment of the metal centers is typical to that of "piano stool"-type complexes. The X-ray analyses and complementary NMR studies (carried out in CD 2 Cl 2) provide evidence for the existence of strong intramolecular hydrogen-bonding interactions between the pyrrolic NH protons and the chloride counteranion both in solution and in the solid state.

Photochemical isomerization of 7-aryl-substituted 1H-Azepin-2(3H)-ones. Formation and X-ray structure determination of atropisomeric ketimines

1983 ◽  
Vol 36 (10) ◽  
pp. 2073 ◽  
Author(s):  
H Becker ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Hydrogen Bonding ◽  
Structure Determination ◽  
Intramolecular Hydrogen Bonding ◽  
Phenolic Hydroxyl ◽  
X Ray Diffraction ◽  
X Ray ◽  
Photochemical Isomerization ◽  
Intramolecular Hydrogen

The structures of two isomeric 3,5-di-t-butyl-2-[(3,5-di-t-butyl-2-hydroxyphenyl){(Z)-methylimino}- methyl]cyclopent-2-en-1-ones, formed upon photoexcitation of 3,5-di-t-butyl-7-(3,5-di-t-butyl-2- hydroxyphenyl)-1-methyl-1H-azepin-2(3H)-one in methanol, have been established by X-ray diffraction, and are found to be examples of atropisomeric ketimines. In both isomers, the geometry of imino substitution is characterized by intramolecular hydrogen bonding with the phenolic hydroxyl.

Synthesis of (PVA/PEG: ZnO and Co3O4) Nanocomposites: Characterization and Gamma Ray Studies

2021 ◽  
Vol 19 (4) ◽  
pp. 47-56
Author(s):  
Hanan H. Jassim ◽  
Fouad Sh. Hashim
Keyword(s):  
Gamma Ray ◽  
Polymer Nanocomposite ◽  
Xrd Analysis ◽  
Polymeric Matrix ◽  
Nanocomposite Films ◽  
X Ray Diffraction ◽  
Field Frequency ◽  
Electric Field Frequency ◽  
Solution Cast ◽  
Ft Ir

Polymer blend (PVA/PEG) and its nanocomposites with constant ZnO and different ratios of Co3O4 NPs films synthesized using solution cast technique. The obtained products were identified by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). Optical characteristics have been studied by UV-visible spectroscopy. FT-IR spectra confirmed of the produce the functional groups present in polymer nanocomposite systems. XRD analysis confirmed the formation nanocomposite films more crystalline from the polymeric matrix. SEM showed a powerful dispersion of ZnO and Co3O4 NPs on the surface of the polymeric matrix. The D.C electrical conductivity of the polymeric system (PVA/PEG) increases after addition of and Co3O4 NPs for all temperatures under test. D.C measurements indicate that all films having one activation energy, and that its value increases with the increase in the percentage of addition. The A.C electrical properties showed that the dielectric constant and dielectric loss for all films decreases with the increase of the electric field frequency, and that its values increase with the increasing of the wt.% of Co3O4 NPs. The (PVA/PEG) and its nanocomposite with ZnO and different wt.% of Co3O4 films have good linear attenuation coefficients for gamma ray radiation.

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