Rauzah Hashim - Academia.edu (original) (raw)
Papers by Rauzah Hashim
Proceedings of SPIE - The International Society for Optical Engineering
The self-assembly phenomena on a special class of poly-hydroxy sugar surfactant have been studied... more The self-assembly phenomena on a special class of poly-hydroxy sugar surfactant have been studied extensively. This class of material is classified as amphitropic liquid crystals since they exhibit both thermotropic and lyotropic liquid crystalline properties. Hence the potential applications of these non-ionic surfactants are more versatile than those from the conventional lyotropic liquid crystals including those from thermotropic phases, but the latters are yet to be realized. Unfortunately, due to the lack of interest (or even awareness), fundamental studies in thermotropic glycolipids are scanty to support application development, and any tangible progress is often mired by the complexity of the sugar stereochemistry. However, some applications may be pursued from these materials by taking the advantage of the sugar chirality and the tilted structure of the lipid organization which implies ferroelectric behavior. Here, we present our studies on the stereochemical diversity of t...
CrystEngComm, 2015
ABSTRACT Long flexible bis-imidazolium dications form discrete multi-component complexes with ani... more ABSTRACT Long flexible bis-imidazolium dications form discrete multi-component complexes with anionic p-sulfonatocalix[4]arene, cationic tetraphenylphosphonium, and hydrated lanthanide ions (La3+ and Gd3+). The terminally charged head groups of the dications reside in either one or two calixarene cavities of different bilayers depending on the length of the terminal alkyl group with the central spacer penetrating across the multi-layers and adjusted to fit in the tight bilayer.
Local heterogeneity in lipid self-assembly is important for executing the cellular membrane funct... more Local heterogeneity in lipid self-assembly is important for executing the cellular membrane functions. In this work, we chemically modified 2-(2′-hydroxyphenyl)benzoxazole (HBO) and attached a C8 alkyl chain in two different locations to probe the microscopic environment of four lipidic phases of dodecyl β-maltoside. The fluorescence change in HBO and the new probes (HBO-1 and HBO-2) shows that in all phases (micellar, hexagonal, cubic and lamellar) three HBO tautomeric species (solvated syn-enol, anionic, and closed syn-keto) are stable. The formation of multi tautomers reflects the heterogeneity of the lipidic phases. The results indicate that HBO and HBO-1 reside in a similar location within the head group region, whereas HBO-2 is slightly pushed away from the sugar-dominated area. The stability of the solvated syn-enol tautomer is due to the formation of a hydrogen bond between the OH group of the HBO moiety and an adjacent oxygen atom of a sugar unit. The detected HBO anions wa...
Proceedings of SPIE - The International Society for Optical Engineering
Water-driven self-assembly of lipids displays a variety of liquid crystalline phases that are cru... more Water-driven self-assembly of lipids displays a variety of liquid crystalline phases that are crucial for membrane functions. In this work, we characterized the temperature-induced phase transitions in aqueous self-assembly systems using steady-state and time-resolved fluorescence measurements. The polar head group region was investigated using tryptophan (Trp) and two of its ester derivatives, and the hydrophobic tail region was probed using pyrene. The spectral changes in tryptophan and pyrene were used as a benchmark to estimate the polarity of the head group region and the tail region, respectively. A basic medium was detected and estimated for the polar region in the inverse cubic phase of a Guerbet glycolipid and was attributed to the structural effect of the narrow nanochannels. All the studied lipid compositions show completely reversible temperature-induced phase transitions, reflecting the thermodynamic equilibrium structures of their mesophases. The results reveal a large...
Although glycolipids exist in nature, they can also be synthesized either chemically or enzymatic... more Although glycolipids exist in nature, they can also be synthesized either chemically or enzymatically. Due to their role in the nervous system and biomembranes, natural glycolipids are extensively studied by researchers, especially biochemists, but their liquid crystal state is not well understood. In this paper, starting from glucose and a series of branched-chain alcohols, novel alkyl glycosides have been synthesized. These compounds have been structurally elucidated using standard spectroscopic techniques like hydrogen (1 H) NMR, carbon-13 (13 C) NMR, and infra-red-(IR) and also using high resolution mass spectrometry (HRMS). Their thermotropic liquid crystalline properties were investigated using polarizing microscopy and differential scanning calorimetry. It was found that the shorter carbon chain analogues gave the smectic A phase while the longer ones gave only the columnar phase. The results were compared with those of the straight chain counterparts.
Liquid Crystals, 2015
ABSTRACT A promising new development in therapeutic nanomedicine includes drug and biomolecule de... more ABSTRACT A promising new development in therapeutic nanomedicine includes drug and biomolecule delivery system using carbon nanotubes dispersed in surfactant, such as glycolipid. To study the interaction between carbon nanotube and surfactant, here we report on a density functional theory (DFT) calculation at the B3LYP/6-31G level of theory performed for the purpose of predicting the reactivity governing the nucleophilic and electrophilic attacks on the external surface of a single-walled carbon nanotube (SWNTs). The DFT-based local reactivity descriptor, Fukui function, local softness and dual reactivity have been examined to predict the reactivity of different carbon atom sites of the SWNTs understudy. In addition, binding energy, high occupied molecular orbital (HOMO), lowest occupied molecular orbital (LUMO) and energy difference between carbon nanotube and the complex (SWNT-surfactant) are determined. The computational results predicted that glycolipid, as a non-ionic surfactant, could result in a strong interaction on the surface of the SWNT in both gas and aqueous phases.
RSC Adv., 2015
ABSTRACT The use of alkyl glycosides as alternatives to other surfactants for pharmaceutical appl... more ABSTRACT The use of alkyl glycosides as alternatives to other surfactants for pharmaceutical applications has received much interest due to their specific carbohydrate interactions, low inherent toxicity, and biodegradability. We have formulated sugar-based vesicles that carry mono- and disaccharide groups using octyl glucoside and maltoside, respectively. The physicochemical properties of the vesicles including size, surface charge, shape, and effect of the cholesterol content on the vesicle stability were investigated using dynamic light scattering and transmission electron microscopy. Stable glucoside (C8G) and maltoside (C8M) vesicles were achieved by incorporation of 20 mol% cholesterol, and 8 mol% dicetyl phosphate charge additives. A model small hydrophilic methylene blue (MB) dye was encapsulated into C8G and C8M, and the leakage of the dye was determined by examining the corresponding fluorescence signal in frequency and time domains. The results indicate a tight binding of MB in C8G, as reflected in the short fluorescence lifetime (s < 0.10 ns) compared to MB in C8M (s ¼ 0.28 ns). This was in agreement with the leakage efficiency of MB which was measured at physiological temperature to be almost zero in MB– C8G, while a ca. 17% leakage was detected for MB–C8M after 30 minutes. The latter shows a ca. 44% leakage after 60 minutes. The larger head group in C8M increases the membrane fluidity, leading to a more flexible vesicle with more leakage efficiency. A local basic environment was observed in dyeencapsulated vesicles, and was attributed to through space interactions between MB and each of the sugar polar sites and the localized water molecules. The vesicles were non-cytotoxic at low concentrations. The current work shows the usefulness of using C8M as a carrier intended for fast release of hydrophilic drugs.
International Journal of Modern Physics B
We have considered a classical lattice-gas model, consisting of a three-dimensional simple-cubic ... more We have considered a classical lattice-gas model, consisting of a three-dimensional simple-cubic lattice, whose sites host three-component unit vectors; pairs of nearestneighboring sites interact via the nematogenic potential here P4(τ) denotes the fourth Legendre polynomial, nuj=0,1 are occupation numbers, uj are unit vectors (classical spins), and ∊ is a positive quantity setting the energy and temperature scales (i.e. T* =kB T / ∊). The total Hamiltonian is given by where ∑{j < k} denotes sum over all distinct nearest-neighboring pairs of lattice sites. The saturated-lattice version of this model defines a nematogenic lattice model, already studied in the literature, and found to possess a transition to an orientationally ordered phase at low temperature; moreover, according to available rigorous results, there exists a μ0<0, such that, for all μ>μ0, the system supports an ordering transition at a finite, μ-dependent, temperature. We present here a detailed study of the ...
International Journal of Modern Physics B
We report here an attempt of directly estimating densities of states, and hence partition functio... more We report here an attempt of directly estimating densities of states, and hence partition functions, for classical lattice-spin models of a rather general type; the method has been applied to a few models in one dimension with nearest-neighbor interactions isotropic in spin space; their exact solutions, available in the literature, are used for unambiguous comparison. After obtaining the appropriate histograms, thermodynamic properties have been calculated over a range of temperatures. At sufficiently high temperatures, the resulting estimates are in very good agreement with available exact results; as expected, the agreement deteriorates at lower temperatures.
The Journal of Physical Chemistry C, 2013
Scientific reports, 2015
Local heterogeneity in lipid self-assembly is important for executing the cellular membrane funct... more Local heterogeneity in lipid self-assembly is important for executing the cellular membrane functions. In this work, we chemically modified 2-(2'-hydroxyphenyl)benzoxazole (HBO) and attached a C8 alkyl chain in two different locations to probe the microscopic environment of four lipidic phases of dodecyl β-maltoside. The fluorescence change in HBO and the new probes (HBO-1 and HBO-2) shows that in all phases (micellar, hexagonal, cubic and lamellar) three HBO tautomeric species (solvated syn-enol, anionic, and closed syn-keto) are stable. The formation of multi tautomers reflects the heterogeneity of the lipidic phases. The results indicate that HBO and HBO-1 reside in a similar location within the head group region, whereas HBO-2 is slightly pushed away from the sugar-dominated area. The stability of the solvated syn-enol tautomer is due to the formation of a hydrogen bond between the OH group of the HBO moiety and an adjacent oxygen atom of a sugar unit. The detected HBO anion...
The Journal of chemical physics, Jan 28, 2014
Glycolipid, found commonly in membranes, is also a liquid crystal material which can self-assembl... more Glycolipid, found commonly in membranes, is also a liquid crystal material which can self-assemble without the presence of a solvent. Here, the dielectric and conductivity properties of three synthetic glycolipid thin films in different thermotropic liquid crystal phases were investigated over a frequency and temperature range of (10(-2)-10(6) Hz) and (303-463 K), respectively. The observed relaxation processes distinguish between the different phases (smectic A, columnar/hexagonal, and bicontinuous cubic Q) and the glycolipid molecular structures. Large dielectric responses were observed in the columnar and bicontinuous cubic phases of the longer branched alkyl chain glycolipids. Glycolipids with the shortest branched alkyl chain experience the most restricted self-assembly dynamic process over the broad temperature range studied compared to the longer ones. A high frequency dielectric absorption (Process I) was observed in all samples. This is related to the dynamics of the hydrog...
A molecular field theory of biaxial nematics formed by molecules with C2h point group symmetry ha... more A molecular field theory of biaxial nematics formed by molecules with C2h point group symmetry has been developed by Luckhurst et al. and a Monte Carlo computer simulation study of this model has been performed by Hashim et al.. In these studies the truncated model pair potential was only applied to molecules whose long axes are taken to be along their C2 rotation axes. The present study extends this work by assuming that the molecular long axis is now perpendicular to the C2 axis, resulting in there being two possible choices of minor axes. It considers the phases formed by both cases. The molecular field theory for these models is formulated and reported here. The theoretical treatment of the present cases gives rise to a new set of order parameters. So as to simplify the pseudo-potentials only the dominant second rank order parameters are considered and evaluated to give the phase behaviour of these truncated models. The predicted phase behaviour is compared with the results from...
Journal of Molecular Structure: THEOCHEM, 1997
The electronic structures of carbazole, N-phenylcarbazole (NPC), cyanophenylcarbazole (CPC) and N... more The electronic structures of carbazole, N-phenylcarbazole (NPC), cyanophenylcarbazole (CPC) and N-ethylcarbazole (NEC) have been calculated using the quantum chemical semi-empirical MINDO/3 method. In this paper, electronic ground states and first singlet ...
RSC Adv., 2014
ABSTRACT An efficient and eco-friendly method is reported for the synthesis of 2,3-dihydroquinazo... more ABSTRACT An efficient and eco-friendly method is reported for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones from the direct cyclocondensation of anthranilamide with aldehydes using p-sulfonic acid calix[4]arene (p-SAC) as a recyclable organocatalyst in excellent yields in water at room temperature. The catalyst was reusable without significant loss of catalytic efficiency. Operational simplicity, the compatibility with various functional groups, non-chromatographic purification technique, high yields and mild reaction conditions are the notable advantages of this procedure. Large scale reaction demonstrated the practical applicability of this methodology.
Advanced Materials Research, 2014
ABSTRACT The phase behaviour and self-assembly structural parameters of a pair of monosaccharide ... more ABSTRACT The phase behaviour and self-assembly structural parameters of a pair of monosaccharide and disaccharide Guerbet branched-chain β-D-glycosides, namely 2-octyldodecyl β-D-glucoside (β-Glc-C12C8) and 2-octyldodecyl β-D-maltoside (β-Mal-C12C8), have been studied by means of optical polarizing microscopy (OPM) and small-angle X-ray diffraction at room temperature (25°C). These compounds are sugar-based glycolipid surfactants having a total chain length of C20, and differ based on the increasing number of hydroxyl groups of the sugar headgroup (glucose and maltose). The repeat spacings obtained by X-ray diffraction as a function of water content have been used to determine the limiting hydration for the two glycosides. At room temperature, β-Glc-C12C8 and β-Mal-C12C8 have limiting hydrations of 22 wt% and 25 wt%, corresponding to 8 10 and 10 12 water molecules per glycoside, respectively. At all water contents between 5 and 29 wt % water, these compounds adopt inverse hexagonal (HII) or fluid lamellar (Lα) phases. The structural parameters of these phases have been determined from the diffraction data, from the X-ray repeat spacings, densities and concentration of the glycosides.
Proceedings of SPIE - The International Society for Optical Engineering
The self-assembly phenomena on a special class of poly-hydroxy sugar surfactant have been studied... more The self-assembly phenomena on a special class of poly-hydroxy sugar surfactant have been studied extensively. This class of material is classified as amphitropic liquid crystals since they exhibit both thermotropic and lyotropic liquid crystalline properties. Hence the potential applications of these non-ionic surfactants are more versatile than those from the conventional lyotropic liquid crystals including those from thermotropic phases, but the latters are yet to be realized. Unfortunately, due to the lack of interest (or even awareness), fundamental studies in thermotropic glycolipids are scanty to support application development, and any tangible progress is often mired by the complexity of the sugar stereochemistry. However, some applications may be pursued from these materials by taking the advantage of the sugar chirality and the tilted structure of the lipid organization which implies ferroelectric behavior. Here, we present our studies on the stereochemical diversity of t...
CrystEngComm, 2015
ABSTRACT Long flexible bis-imidazolium dications form discrete multi-component complexes with ani... more ABSTRACT Long flexible bis-imidazolium dications form discrete multi-component complexes with anionic p-sulfonatocalix[4]arene, cationic tetraphenylphosphonium, and hydrated lanthanide ions (La3+ and Gd3+). The terminally charged head groups of the dications reside in either one or two calixarene cavities of different bilayers depending on the length of the terminal alkyl group with the central spacer penetrating across the multi-layers and adjusted to fit in the tight bilayer.
Local heterogeneity in lipid self-assembly is important for executing the cellular membrane funct... more Local heterogeneity in lipid self-assembly is important for executing the cellular membrane functions. In this work, we chemically modified 2-(2′-hydroxyphenyl)benzoxazole (HBO) and attached a C8 alkyl chain in two different locations to probe the microscopic environment of four lipidic phases of dodecyl β-maltoside. The fluorescence change in HBO and the new probes (HBO-1 and HBO-2) shows that in all phases (micellar, hexagonal, cubic and lamellar) three HBO tautomeric species (solvated syn-enol, anionic, and closed syn-keto) are stable. The formation of multi tautomers reflects the heterogeneity of the lipidic phases. The results indicate that HBO and HBO-1 reside in a similar location within the head group region, whereas HBO-2 is slightly pushed away from the sugar-dominated area. The stability of the solvated syn-enol tautomer is due to the formation of a hydrogen bond between the OH group of the HBO moiety and an adjacent oxygen atom of a sugar unit. The detected HBO anions wa...
Proceedings of SPIE - The International Society for Optical Engineering
Water-driven self-assembly of lipids displays a variety of liquid crystalline phases that are cru... more Water-driven self-assembly of lipids displays a variety of liquid crystalline phases that are crucial for membrane functions. In this work, we characterized the temperature-induced phase transitions in aqueous self-assembly systems using steady-state and time-resolved fluorescence measurements. The polar head group region was investigated using tryptophan (Trp) and two of its ester derivatives, and the hydrophobic tail region was probed using pyrene. The spectral changes in tryptophan and pyrene were used as a benchmark to estimate the polarity of the head group region and the tail region, respectively. A basic medium was detected and estimated for the polar region in the inverse cubic phase of a Guerbet glycolipid and was attributed to the structural effect of the narrow nanochannels. All the studied lipid compositions show completely reversible temperature-induced phase transitions, reflecting the thermodynamic equilibrium structures of their mesophases. The results reveal a large...
Although glycolipids exist in nature, they can also be synthesized either chemically or enzymatic... more Although glycolipids exist in nature, they can also be synthesized either chemically or enzymatically. Due to their role in the nervous system and biomembranes, natural glycolipids are extensively studied by researchers, especially biochemists, but their liquid crystal state is not well understood. In this paper, starting from glucose and a series of branched-chain alcohols, novel alkyl glycosides have been synthesized. These compounds have been structurally elucidated using standard spectroscopic techniques like hydrogen (1 H) NMR, carbon-13 (13 C) NMR, and infra-red-(IR) and also using high resolution mass spectrometry (HRMS). Their thermotropic liquid crystalline properties were investigated using polarizing microscopy and differential scanning calorimetry. It was found that the shorter carbon chain analogues gave the smectic A phase while the longer ones gave only the columnar phase. The results were compared with those of the straight chain counterparts.
Liquid Crystals, 2015
ABSTRACT A promising new development in therapeutic nanomedicine includes drug and biomolecule de... more ABSTRACT A promising new development in therapeutic nanomedicine includes drug and biomolecule delivery system using carbon nanotubes dispersed in surfactant, such as glycolipid. To study the interaction between carbon nanotube and surfactant, here we report on a density functional theory (DFT) calculation at the B3LYP/6-31G level of theory performed for the purpose of predicting the reactivity governing the nucleophilic and electrophilic attacks on the external surface of a single-walled carbon nanotube (SWNTs). The DFT-based local reactivity descriptor, Fukui function, local softness and dual reactivity have been examined to predict the reactivity of different carbon atom sites of the SWNTs understudy. In addition, binding energy, high occupied molecular orbital (HOMO), lowest occupied molecular orbital (LUMO) and energy difference between carbon nanotube and the complex (SWNT-surfactant) are determined. The computational results predicted that glycolipid, as a non-ionic surfactant, could result in a strong interaction on the surface of the SWNT in both gas and aqueous phases.
RSC Adv., 2015
ABSTRACT The use of alkyl glycosides as alternatives to other surfactants for pharmaceutical appl... more ABSTRACT The use of alkyl glycosides as alternatives to other surfactants for pharmaceutical applications has received much interest due to their specific carbohydrate interactions, low inherent toxicity, and biodegradability. We have formulated sugar-based vesicles that carry mono- and disaccharide groups using octyl glucoside and maltoside, respectively. The physicochemical properties of the vesicles including size, surface charge, shape, and effect of the cholesterol content on the vesicle stability were investigated using dynamic light scattering and transmission electron microscopy. Stable glucoside (C8G) and maltoside (C8M) vesicles were achieved by incorporation of 20 mol% cholesterol, and 8 mol% dicetyl phosphate charge additives. A model small hydrophilic methylene blue (MB) dye was encapsulated into C8G and C8M, and the leakage of the dye was determined by examining the corresponding fluorescence signal in frequency and time domains. The results indicate a tight binding of MB in C8G, as reflected in the short fluorescence lifetime (s < 0.10 ns) compared to MB in C8M (s ¼ 0.28 ns). This was in agreement with the leakage efficiency of MB which was measured at physiological temperature to be almost zero in MB– C8G, while a ca. 17% leakage was detected for MB–C8M after 30 minutes. The latter shows a ca. 44% leakage after 60 minutes. The larger head group in C8M increases the membrane fluidity, leading to a more flexible vesicle with more leakage efficiency. A local basic environment was observed in dyeencapsulated vesicles, and was attributed to through space interactions between MB and each of the sugar polar sites and the localized water molecules. The vesicles were non-cytotoxic at low concentrations. The current work shows the usefulness of using C8M as a carrier intended for fast release of hydrophilic drugs.
International Journal of Modern Physics B
We have considered a classical lattice-gas model, consisting of a three-dimensional simple-cubic ... more We have considered a classical lattice-gas model, consisting of a three-dimensional simple-cubic lattice, whose sites host three-component unit vectors; pairs of nearestneighboring sites interact via the nematogenic potential here P4(τ) denotes the fourth Legendre polynomial, nuj=0,1 are occupation numbers, uj are unit vectors (classical spins), and ∊ is a positive quantity setting the energy and temperature scales (i.e. T* =kB T / ∊). The total Hamiltonian is given by where ∑{j < k} denotes sum over all distinct nearest-neighboring pairs of lattice sites. The saturated-lattice version of this model defines a nematogenic lattice model, already studied in the literature, and found to possess a transition to an orientationally ordered phase at low temperature; moreover, according to available rigorous results, there exists a μ0<0, such that, for all μ>μ0, the system supports an ordering transition at a finite, μ-dependent, temperature. We present here a detailed study of the ...
International Journal of Modern Physics B
We report here an attempt of directly estimating densities of states, and hence partition functio... more We report here an attempt of directly estimating densities of states, and hence partition functions, for classical lattice-spin models of a rather general type; the method has been applied to a few models in one dimension with nearest-neighbor interactions isotropic in spin space; their exact solutions, available in the literature, are used for unambiguous comparison. After obtaining the appropriate histograms, thermodynamic properties have been calculated over a range of temperatures. At sufficiently high temperatures, the resulting estimates are in very good agreement with available exact results; as expected, the agreement deteriorates at lower temperatures.
The Journal of Physical Chemistry C, 2013
Scientific reports, 2015
Local heterogeneity in lipid self-assembly is important for executing the cellular membrane funct... more Local heterogeneity in lipid self-assembly is important for executing the cellular membrane functions. In this work, we chemically modified 2-(2'-hydroxyphenyl)benzoxazole (HBO) and attached a C8 alkyl chain in two different locations to probe the microscopic environment of four lipidic phases of dodecyl β-maltoside. The fluorescence change in HBO and the new probes (HBO-1 and HBO-2) shows that in all phases (micellar, hexagonal, cubic and lamellar) three HBO tautomeric species (solvated syn-enol, anionic, and closed syn-keto) are stable. The formation of multi tautomers reflects the heterogeneity of the lipidic phases. The results indicate that HBO and HBO-1 reside in a similar location within the head group region, whereas HBO-2 is slightly pushed away from the sugar-dominated area. The stability of the solvated syn-enol tautomer is due to the formation of a hydrogen bond between the OH group of the HBO moiety and an adjacent oxygen atom of a sugar unit. The detected HBO anion...
The Journal of chemical physics, Jan 28, 2014
Glycolipid, found commonly in membranes, is also a liquid crystal material which can self-assembl... more Glycolipid, found commonly in membranes, is also a liquid crystal material which can self-assemble without the presence of a solvent. Here, the dielectric and conductivity properties of three synthetic glycolipid thin films in different thermotropic liquid crystal phases were investigated over a frequency and temperature range of (10(-2)-10(6) Hz) and (303-463 K), respectively. The observed relaxation processes distinguish between the different phases (smectic A, columnar/hexagonal, and bicontinuous cubic Q) and the glycolipid molecular structures. Large dielectric responses were observed in the columnar and bicontinuous cubic phases of the longer branched alkyl chain glycolipids. Glycolipids with the shortest branched alkyl chain experience the most restricted self-assembly dynamic process over the broad temperature range studied compared to the longer ones. A high frequency dielectric absorption (Process I) was observed in all samples. This is related to the dynamics of the hydrog...
A molecular field theory of biaxial nematics formed by molecules with C2h point group symmetry ha... more A molecular field theory of biaxial nematics formed by molecules with C2h point group symmetry has been developed by Luckhurst et al. and a Monte Carlo computer simulation study of this model has been performed by Hashim et al.. In these studies the truncated model pair potential was only applied to molecules whose long axes are taken to be along their C2 rotation axes. The present study extends this work by assuming that the molecular long axis is now perpendicular to the C2 axis, resulting in there being two possible choices of minor axes. It considers the phases formed by both cases. The molecular field theory for these models is formulated and reported here. The theoretical treatment of the present cases gives rise to a new set of order parameters. So as to simplify the pseudo-potentials only the dominant second rank order parameters are considered and evaluated to give the phase behaviour of these truncated models. The predicted phase behaviour is compared with the results from...
Journal of Molecular Structure: THEOCHEM, 1997
The electronic structures of carbazole, N-phenylcarbazole (NPC), cyanophenylcarbazole (CPC) and N... more The electronic structures of carbazole, N-phenylcarbazole (NPC), cyanophenylcarbazole (CPC) and N-ethylcarbazole (NEC) have been calculated using the quantum chemical semi-empirical MINDO/3 method. In this paper, electronic ground states and first singlet ...
RSC Adv., 2014
ABSTRACT An efficient and eco-friendly method is reported for the synthesis of 2,3-dihydroquinazo... more ABSTRACT An efficient and eco-friendly method is reported for the synthesis of 2,3-dihydroquinazolin-4(1H)-ones from the direct cyclocondensation of anthranilamide with aldehydes using p-sulfonic acid calix[4]arene (p-SAC) as a recyclable organocatalyst in excellent yields in water at room temperature. The catalyst was reusable without significant loss of catalytic efficiency. Operational simplicity, the compatibility with various functional groups, non-chromatographic purification technique, high yields and mild reaction conditions are the notable advantages of this procedure. Large scale reaction demonstrated the practical applicability of this methodology.
Advanced Materials Research, 2014
ABSTRACT The phase behaviour and self-assembly structural parameters of a pair of monosaccharide ... more ABSTRACT The phase behaviour and self-assembly structural parameters of a pair of monosaccharide and disaccharide Guerbet branched-chain β-D-glycosides, namely 2-octyldodecyl β-D-glucoside (β-Glc-C12C8) and 2-octyldodecyl β-D-maltoside (β-Mal-C12C8), have been studied by means of optical polarizing microscopy (OPM) and small-angle X-ray diffraction at room temperature (25°C). These compounds are sugar-based glycolipid surfactants having a total chain length of C20, and differ based on the increasing number of hydroxyl groups of the sugar headgroup (glucose and maltose). The repeat spacings obtained by X-ray diffraction as a function of water content have been used to determine the limiting hydration for the two glycosides. At room temperature, β-Glc-C12C8 and β-Mal-C12C8 have limiting hydrations of 22 wt% and 25 wt%, corresponding to 8 10 and 10 12 water molecules per glycoside, respectively. At all water contents between 5 and 29 wt % water, these compounds adopt inverse hexagonal (HII) or fluid lamellar (Lα) phases. The structural parameters of these phases have been determined from the diffraction data, from the X-ray repeat spacings, densities and concentration of the glycosides.