Abstract The integration of inorganic nanoparticles into a polymer matrix presents a category of ... more Abstract The integration of inorganic nanoparticles into a polymer matrix presents a category of advanced materials, known as polymer inorganic nanocomposites (PINCs). In present work, the γ-ray shielding parameters of epoxy resin loaded with two different proportions (5 and 25 wt%) of Pb, Zn, ZnO, Ti and TiO2 inorganic nanoparticles have been investigated. The prepared samples were characterized through structural investigations including SEM, EDS, XRD and FT-IR analyses. Furthermore, mechanical properties of the nanocomposites were evaluated on the basis of compressive strength. To evaluate the γ-ray attenuation performance of the nanocomposites, the transmission and flux buildup factors have been measured experimentally. The 59.54 and 662 keV γ-rays emitted from 241Am and 137Cs point sources were counted by a 2″ × 2″ NaI(Tl) detector. In addition, experimental results has been confirmed by a theoretical study using MCNPX code. The results showed that γ-ray shielding effectiveness was enhanced by the increment of the filler loading. The experimental and theoretical calculations of transmission and buildup factors were found to be in a good agreement. As expected, 25 wt% Pb/epoxy nanocomposites indicated better shielding properties than their counterparts. However, it has to be notices that the mechanical strength of Pb/epoxy nanocomposites were determined significantly lower than those of Zn, ZnO, Ti and TiO2/epoxy nanocomposites. To design and choose an appropriate shielding material, therefore, a number of factors have to be considered.
Repetitivity of 21-axis symmetry element in three polymorphic crystal structures of carboxamide c... more Repetitivity of 21-axis symmetry element in three polymorphic crystal structures of carboxamide compound with high Z′ packing problem.
Pharmaceutical cocrystals are well-investigated compounds in which properties of active pharmaceu... more Pharmaceutical cocrystals are well-investigated compounds in which properties of active pharmaceutical ingredients (APIs). Drugs are generally classified into the four categories in the Biopharmaceutics Classification System (BCS): class I (high solubility, high permeability), class II (low solubility, high permeability), class III (high solubility, low permeability), and class IV (low solubility, low permeability). Poor solubility and/or permeability of APIs are the main factors to restrict the bioavailability of APIs during drug discovery and development. Many approaches have been employed to improve the solubility and permeability of APIs. Gliclazide (GCZ), Tolbutamide (TOL) and Glipizide (GPZ) are BCS class II antidiabetic drugs with poor aqueous solubility. Multicomponent solid forms, salts and cocrystals of GCZ were obtained upon liquid assisted grinding (LAG) with coformers of catechol (CAT), resorcinol (RES), p-toluenesulfonic acid (PTSA) and piperazine (PPZ). Solubility of TOL and GPZ have been modified by salt formation with PPZ. The multicomponent solids were characterized by single crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) and further subjected to solubility studies. The cocrystals/salts, in all cases, showed improvements in the solubility and dissolution rates compared to the parent APIs. GCZ −PPZ, TOL−PPZ (I) and GPZ−PPZ showed 6.6, 80 and 89.4 fold enhancements respectively in the solubility. The reasons for the improved solubility of the cocrystals/salts in terms of drug-coformer interactions are discussed. While salt formation can enhance solubility by 100-1000 times, cocrystal formation can increase it typically 4−160 fold. It is to be noted that the solution crystallization of these drugs is tedious and often results in poor crystals that were obtained slowly, after many months. This could be due to the entropic reason arising from the molecular flexibility which prolongs the crystallization process. In the case of TOL-PPZ (I) the DSC peak is split into two peaks. We conclude that this observation may have to do with the presence of two TOL polymorphs in the mortar which might lead to two different polymorphic salts when ground with PPZ.
On the base of our previous studies due to the presence of halides in our complexes there is stro... more On the base of our previous studies due to the presence of halides in our complexes there is strong probability for obtaining coordination polymers. Crystal engineering well-defined as the understanding of intermolecular interactions in the context of crystal packing and the utilization of such understanding in the design of new solids with desired physical and chemical properties. Owing to the fact that the small changes in the ligands may play a significant role in the complexes, the organic ligand (1-naphtyl pyridine-2-carboxylate) (L), was synthesized. In order make more steric repulsion around of the complexes resulted in the substitution effect around of the naphtyl moiety was hired in the design. Relocation in the position of functional group was fulfilled our expectations. Three new mercury (II) halide complexes, [Hg(L)2Cl2] (1), [Hg(L)2Br2] (2) and [Hg(L)2I2] (3) were synthesized. All of the compounds were fully characterized using FT-IR, TGA, DSC, mass spectrometry, CHNOS elemental analyses, PXRD, NMR and SCXRD. The results indicate that metal-ligand polymerization controlled by substitution effect. The coordination geometry around the Hg (II) ion is seesaw shape in distorted tetrahedral geometry for compounds (1), (2) and (3) with τ4 of 0.74, 0.76 and 0.78, respectively. Due to the replacement of the functional group (mentioned substitution effect), flexibility of coodinated ligand was decreased. In the previously reported structures, the angle between two planes of aromatic rings in the analogous ligand was 78.37o which changed to the 59.47o, 50.75o and 64.90o for mercury halide series complexes. In present study these angles are 89.09, 89.73 and 88.90 for titled complexes based on new designed ligand. Consequently, this study emphasize that the substitution effect can play the significant role through the flexibility of designed ligand to control the metal-ligand polymerization. [1] Desiraju.
The coordination sphere can be influenced by many factors of inorganic and organic units. Despite... more The coordination sphere can be influenced by many factors of inorganic and organic units. Despite the predominant role of inorganic unit in coordination sphere determination, organic unit can change it via one major or cooperativity of minor effects.
Repetitivity of 21-axis symmetry element in three polymorphic crystal structures of carboxamide c... more Repetitivity of 21-axis symmetry element in three polymorphic crystal structures of carboxamide compound with high Z′ packing problem.
Abstract The integration of inorganic nanoparticles into a polymer matrix presents a category of ... more Abstract The integration of inorganic nanoparticles into a polymer matrix presents a category of advanced materials, known as polymer inorganic nanocomposites (PINCs). In present work, the γ-ray shielding parameters of epoxy resin loaded with two different proportions (5 and 25 wt%) of Pb, Zn, ZnO, Ti and TiO2 inorganic nanoparticles have been investigated. The prepared samples were characterized through structural investigations including SEM, EDS, XRD and FT-IR analyses. Furthermore, mechanical properties of the nanocomposites were evaluated on the basis of compressive strength. To evaluate the γ-ray attenuation performance of the nanocomposites, the transmission and flux buildup factors have been measured experimentally. The 59.54 and 662 keV γ-rays emitted from 241Am and 137Cs point sources were counted by a 2″ × 2″ NaI(Tl) detector. In addition, experimental results has been confirmed by a theoretical study using MCNPX code. The results showed that γ-ray shielding effectiveness was enhanced by the increment of the filler loading. The experimental and theoretical calculations of transmission and buildup factors were found to be in a good agreement. As expected, 25 wt% Pb/epoxy nanocomposites indicated better shielding properties than their counterparts. However, it has to be notices that the mechanical strength of Pb/epoxy nanocomposites were determined significantly lower than those of Zn, ZnO, Ti and TiO2/epoxy nanocomposites. To design and choose an appropriate shielding material, therefore, a number of factors have to be considered.
Repetitivity of 21-axis symmetry element in three polymorphic crystal structures of carboxamide c... more Repetitivity of 21-axis symmetry element in three polymorphic crystal structures of carboxamide compound with high Z′ packing problem.
Pharmaceutical cocrystals are well-investigated compounds in which properties of active pharmaceu... more Pharmaceutical cocrystals are well-investigated compounds in which properties of active pharmaceutical ingredients (APIs). Drugs are generally classified into the four categories in the Biopharmaceutics Classification System (BCS): class I (high solubility, high permeability), class II (low solubility, high permeability), class III (high solubility, low permeability), and class IV (low solubility, low permeability). Poor solubility and/or permeability of APIs are the main factors to restrict the bioavailability of APIs during drug discovery and development. Many approaches have been employed to improve the solubility and permeability of APIs. Gliclazide (GCZ), Tolbutamide (TOL) and Glipizide (GPZ) are BCS class II antidiabetic drugs with poor aqueous solubility. Multicomponent solid forms, salts and cocrystals of GCZ were obtained upon liquid assisted grinding (LAG) with coformers of catechol (CAT), resorcinol (RES), p-toluenesulfonic acid (PTSA) and piperazine (PPZ). Solubility of TOL and GPZ have been modified by salt formation with PPZ. The multicomponent solids were characterized by single crystal X-ray diffraction (SCXRD), powder X-ray diffraction (PXRD), fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) and further subjected to solubility studies. The cocrystals/salts, in all cases, showed improvements in the solubility and dissolution rates compared to the parent APIs. GCZ −PPZ, TOL−PPZ (I) and GPZ−PPZ showed 6.6, 80 and 89.4 fold enhancements respectively in the solubility. The reasons for the improved solubility of the cocrystals/salts in terms of drug-coformer interactions are discussed. While salt formation can enhance solubility by 100-1000 times, cocrystal formation can increase it typically 4−160 fold. It is to be noted that the solution crystallization of these drugs is tedious and often results in poor crystals that were obtained slowly, after many months. This could be due to the entropic reason arising from the molecular flexibility which prolongs the crystallization process. In the case of TOL-PPZ (I) the DSC peak is split into two peaks. We conclude that this observation may have to do with the presence of two TOL polymorphs in the mortar which might lead to two different polymorphic salts when ground with PPZ.
On the base of our previous studies due to the presence of halides in our complexes there is stro... more On the base of our previous studies due to the presence of halides in our complexes there is strong probability for obtaining coordination polymers. Crystal engineering well-defined as the understanding of intermolecular interactions in the context of crystal packing and the utilization of such understanding in the design of new solids with desired physical and chemical properties. Owing to the fact that the small changes in the ligands may play a significant role in the complexes, the organic ligand (1-naphtyl pyridine-2-carboxylate) (L), was synthesized. In order make more steric repulsion around of the complexes resulted in the substitution effect around of the naphtyl moiety was hired in the design. Relocation in the position of functional group was fulfilled our expectations. Three new mercury (II) halide complexes, [Hg(L)2Cl2] (1), [Hg(L)2Br2] (2) and [Hg(L)2I2] (3) were synthesized. All of the compounds were fully characterized using FT-IR, TGA, DSC, mass spectrometry, CHNOS elemental analyses, PXRD, NMR and SCXRD. The results indicate that metal-ligand polymerization controlled by substitution effect. The coordination geometry around the Hg (II) ion is seesaw shape in distorted tetrahedral geometry for compounds (1), (2) and (3) with τ4 of 0.74, 0.76 and 0.78, respectively. Due to the replacement of the functional group (mentioned substitution effect), flexibility of coodinated ligand was decreased. In the previously reported structures, the angle between two planes of aromatic rings in the analogous ligand was 78.37o which changed to the 59.47o, 50.75o and 64.90o for mercury halide series complexes. In present study these angles are 89.09, 89.73 and 88.90 for titled complexes based on new designed ligand. Consequently, this study emphasize that the substitution effect can play the significant role through the flexibility of designed ligand to control the metal-ligand polymerization. [1] Desiraju.
The coordination sphere can be influenced by many factors of inorganic and organic units. Despite... more The coordination sphere can be influenced by many factors of inorganic and organic units. Despite the predominant role of inorganic unit in coordination sphere determination, organic unit can change it via one major or cooperativity of minor effects.
Repetitivity of 21-axis symmetry element in three polymorphic crystal structures of carboxamide c... more Repetitivity of 21-axis symmetry element in three polymorphic crystal structures of carboxamide compound with high Z′ packing problem.
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