Nonpolar Organic Solvents Research Articles

Size-dependent oxidation of monodisperse silicon nanocrystals with allylphenylsulfide surfaces.

The synthesis and characterization of size-separated silicon nanocrystals functionalized with a heteroatom-substituted organic capping group, allylphenylsulfide, via photochemical hydrosilylation are described for the first time. These silicon nanocrystals form colloidally stable and highly photoluminescent dispersions in non-polar organic solvents with an absolute quantum yield as high as 52% which is 20% above that of the allylbenzene analogue. Solutions of the size-separated fractions are characterized over time to monitor the effect of aging in air by following the change of their photoluminescence and absolute quantum yields, supplemented by transmission electron microscopy.

Self-aggregation of synthetic zinc chlorophyll derivatives possessing 3(1)-hydroxy or methoxy group and 13(1)-mono- or dicyanomethylene moiety in nonpolar organic solvents as models of chlorosomal bacteriochlorophyll-d aggregates.

Methyl 13(1)-(di)cyanomethylene-pyropheophorbides were synthesized by Knoevenagel reactions of the corresponding 13(1)-oxo-chlorins prepared from modifying chlorophyll-a with malononitrile or cyanoacetic acid. Alternatively, methyl 13(1)-cyanomethylene-pyropheophorbides were produced by Wittig reactions of 13(1)-oxo-chlorins with Ph3P=CHCN. Self-aggregation of zinc complexes of the semi-synthetic chlorophyll derivatives possessing a hydroxy or methoxy group at the 3(1)-position was examined in 1%(v/v) tetrahydrofuran or dichloromethane and hexane by electronic absorption and circular dichroism spectroscopy. Although intermolecular hydrogen-bonding between the 3(1)-hydroxy and 13(1)-oxo groups of bacteriochlorophylls-c/d/e/f was essential for their self-aggregation in natural light-harvesting antenna systems (=chlorosomes), zinc 3(1)-hydroxy-13(1)-di/monocyanomethylene-chlorins self-aggregated in the less/lesser polar organic solvents to form chlorosome-like large oligomers in spite of lacking the 13(1)-oxo moiety as the hydrogen-bonding acceptor. Zinc 3(1)-methoxy-13(1)-dicyanomethylene-chlorin gave similar self-aggregates regardless of lack of both the 3(1)-hydroxy and 13(1)-oxo groups. The present self-aggregation was ascribable to stronger coordination of the 3(1)-oxygen atom to the central zinc than the conventional systems, where the electron-withdrawing cyano group(s) increased the coordinative ability of the central zinc through the chlorin π-system.

Removal of heavy metal ions with the use of chelating polymers obtained by grafting pyridine–pyrazole ligands onto polymethylhydrosiloxane

Abstract New chelating polymers soluble in organic non-polar solvents were synthesized by hydrosilylation reaction of polymethylhydrosiloxane with pyridine–pyrazole ligands. Two types of linkers were used to graft pyridine–pyrazole ligands onto polymethylhydrosiloxane. The composition and properties of the polymers obtained were studied by NMR spectroscopy, Fourier transform infrared spectroscopy, elemental analysis, thermogravimetric analysis and derivative scanning calorimetry. The effects of various parameters such as initial metal ion concentration, contact time, temperature and pH were examined in the processes of extraction of Cu 2+ , Cd 2+ , Cr 3+ , Ni 2+ and Co 2+ . The equilibrium data were best represented by Langmuir isotherm and the uptake capacities of polymers obtained varied between 0.24 mmol (for Co 2+ ) and 1.48 mmol (for Cu 2+ ) per 1 g of polymer. The adsorption kinetics was found to follow the pseudo-second-order kinetic model. The polymers adsorption capacity was more than 90% level after five cycles of adsorption–desorption. Treatment of real wastewater samples showed good ability of the polymers to absorb metal ions.

New lipophilic polyelectrolyte gels containing quaternary ammonium salt with superabsorbent capacity for organic solvents.

Water and soil pollution by organic pollutants from petrochemical plants has become one of the major environmental problems in recent years. Lipophilic polyelectrolyte gels with ionic groups dissociable in nonpolar organic solvents show an enhanced swelling ability in a corresponding media attributed to the electrostatic repulsion and osmotic pressure provided by dissociated ionic groups. Here, we synthesized new lipophilic polyelectrolyte gels based on an easily available electrolyte monomer, methacryloxyethyl dimethyloctane ammonium trifluoromethanesulfonimide (MODAT), and a lipophilic neutral monomer, dodecyl acrylate by radiation-induced polymerization and cross-linking. The resultant lipophilic polyelectrolyte gels could absorb plenty of organic solvents with dielectric constants lower than 20 and exhibited a high absorbing ability at a wide range of temperatures (0-40 °C). The maximum swelling degree could reach as high as 200 g/g in some media, such as 1,2-dichloroethane (199.4 g/g) and dichloromethane (204 g/g), which was much higher than that of the nonionic gel without the addition of MODAT. Moreover, the resultant lipophilic polyelectrolyte gels could release most of the absorbed solvents within several hours and then be reused. It is expected that this new type of lipophilic polyelectrolyte gels may be a suitable candidate as organic pollutant absorbents.

Predictive Multiscale Modeling of Nanocellulose Based Materials and Systems

Cellulose Nanocrysals (CNC) is a renewable biodegradable biopolymer with outstanding mechanical properties made from highly abundant natural source, and therefore is very attractive as reinforcing additive to replace petroleum-based plastics in biocomposite materials, foams, and gels. Large-scale applications of CNC are currently limited due to its low solubility in non-polar organic solvents used in existing polymerization technologies. The solvation properties of CNC can be improved by chemical modification of its surface. Development of effective surface modifications has been rather slow because extensive chemical modifications destabilize the hydrogen bonding network of cellulose and deteriorate the mechanical properties of CNC. We employ predictive multiscale theory, modeling, and simulation to gain a fundamental insight into the effect of CNC surface modifications on hydrogen bonding, CNC crystallinity, solvation thermodynamics, and CNC compatibilization with the existing polymerization technologies, so as to rationally design green nanomaterials with improved solubility in non-polar solvents, controlled liquid crystal ordering and optimized extrusion properties. An essential part of this multiscale modeling approach is the statistical- mechanical 3D-RISM-KH molecular theory of solvation, coupled with quantum mechanics, molecular mechanics, and multistep molecular dynamics simulation. The 3D-RISM-KH theory provides predictive modeling of both polar and non-polar solvents, solvent mixtures, and electrolyte solutions in a wide range of concentrations and thermodynamic states. It properly accounts for effective interactions in solution such as steric effects, hydrophobicity and hydrophilicity, hydrogen bonding, salt bridges, buffer, co-solvent, and successfully predicts solvation effects and processes in bulk liquids, solvation layers at solid surface, and in pockets and other inner spaces of macromolecules and supramolecular assemblies. This methodology enables rational design of CNC-based bionanocomposite materials and systems. Furthermore, the 3D-RISM-KH based multiscale modeling addresses the effect of hemicellulose and lignin composition on nanoscale forces that control cell wall strength towards overcoming plant biomass recalcitrance. It reveals molecular forces maintaining the cell wall structure and provides directions for genetic modulation of plants and pretreatment design to render biomass more amenable to processing. We envision integrated biomass valorization based on extracting and decomposing the non-cellulosic components to low molecular weight chemicals and utilizing the cellulose microfibrils to make CNC. This is an important alternative to approaches of full conversion of lignocellulose to biofuels that face challenges arising from the deleterious impact of cellulose crystallinity on enzymatic processing.

Photoelectrical properties of surfactant-free kesterite Cu2ZnSnSe4 hydrophilic nanocrystal ink and the stability in polar solvents

Colloidal semiconductor nanocrystals (NCs) with surfactant/ligand capping have easy solubility in nonpolar organic solvents but have hindered charge transport, diminishing the electrical efficiency of the material. In the present article, synthesis of bare Cu2ZnSnSe4 NCs of 20–30 nm average diameter with high quality and phase purity has been demonstrated by a simple hydrothermal route, without using any surfactant and hazardous organic solvents. As-synthesized samples can be easily dispersed in polar solvents by electrostatic stabilization and utilized for thin film fabrication. Photovoltaic cell made from the fine high-quality bare Cu2ZnSnSe4 NCs shows accountable fourfold photoresponse electrical conductivity upon illumination (AM 1.5) attributed to ligand-free nature of the synthesized nanoparticles. The dispersibility of the material in a variety of solvents providing electrostatic stabilization has been explored for application purpose which is useful for the material utilization without any pre- or post-deposition treatment for low-cost photovoltaic applications.

Dynamic solvation shell and solubility of C60 in organic solvents.

The notion of (static) solvation shells has recently proved fruitful in revealing key molecular factors that dictate the solubility and aggregation properties of fullerene species in polar or ionic solvent media. Using molecular dynamics schemes with carefully evaluated force fields, we have scrutinized both the static and the dynamic features of the solvation shells of single C60 particle for three nonpolar organic solvents (i.e., chloroform, toluene, and chlorobenzene) and a range of system temperatures (i.e., T = 250-330 K). The central findings have been that, while the static structures of the solvation shell remain, in general, insensitive to the effects of changing solvent type or system temperature, the dynamic behavior of solvent molecules within the shell exhibits prominent dependence on both factors. Detailed analyses led us to propose the notion of dynamically stable solvation shell, effectiveness of which can be characterized by a new physical parameter defined as the ratio of two fundamental time constants representing, respectively, the solvent relaxation (or residence) time within the first solvation shell and the characteristic time required for the fullerene particle to diffuse a distance comparable to the shell thickness. We show that, for the five (two from the literature) different solvent media and the range of system temperatures examined herein, this parameter bears a value around unity and, in particular, correlates intimately with known trends of solubility for C60 solutions. We also provide evidence revealing that, in addition to fullerene-solvent interactions, solvent-solvent interactions play an important role, too, in shaping the dynamic solvation shell, as implied by recent experimental trends.

Low temperature studies of the photoluminescence from colloidal CdSe nanocrystals prepared by the hot injection method in liquid paraffin

This article describes the results from low temperature studies of the photoluminescence (PL) from colloidal CdSe nanocrystals prepared by the hot injection method in liquid paraffin. The synthesized nanocrystals were taken from the reaction mixture at different time intervals, their sizes were all within the quantum confinement range, and showed the typical size-dependent UV–vis absorption, PL and Raman spectral characteristics. The PL spectra and their temperature dependences were measured from room temperature (295K) down to temperatures as low as 15K, demonstrating that the exciton PL transitions followed the Varshni equation. The thermal quenching activation energy below 100K was relatively low, while the luminescence was strongly quenched as the temperature was increased above 100K, probably pointing at change in the degree of carrier localization. The smallest (2.6nm in size) CdSe nanocrystals isolated in the beginning of the nanocrystal growth had a relatively symmetric size distribution and showed a single exciton emission band, while the samples isolated at later stages of the growth process showed negatively skewed asymmetric size distribution, indicating that the growth mechanism of nanocrystals could be explained by the model of Ostwald ripening. The obtained results are expected to be helpful for better understanding of the PL properties of quantum dots and their formation and growth in non-polar organic solvents.

Porous metal-organic frameworks incorporating mixed ligands

Metal-organic frameworks (MOFs), infinite systems built up of metal ions and organic ligands have been extensively studied in materials and supramolecular chemistry due their structural diversity and application as porous materials, in catalysis, ion exchange, gas storage and purification. [1] A novel, 2-fold interpenetrated, pillared, cadmium metal-organic framework was synthesized using trimesic acid and 1,2-bis(4-pyridyl)ethane.[2] Single crystal X-ray analysis revealed a 2-fold interpenetrated, 3-dimensional framework which exhibits a 3,5-connected network with the Schläfli symbol of [(6^3)(6^9.8)] and hms topology. This compound exhibits a temperature-induced single-to-crystal-single-crystal (SC–SC) transformation upon the release of N,N'-dimethylformamide (stable up to 3000C). SC–SC transformation was also observed when the desolvated form absorbed selected polar and non-polar organic solvents. In addition, gas (N_2, CO_2 and N_2O) sorption experiments were performed showing 2.5% N_2, 4.5% CO_2 and 3.4% N_2O absorption by mass at room temperature and moderate gas pressures (~10 bar). A similar MOF was produced when 1,3,5-benzenetricarboxylic acid was replaced with 5-nitro-1,3-benzenedicarboxylic acid. This MOF displays 4-fold interpenetration and also maintains the host framework structure upon heating.

Smart Cleaning Properties of a Multi Tolerance Keratinolytic Protease from an Extremophilic Bacillus tequilensis hsTKB2: Prediction of Enzyme Modification Site

Bacillus tequilensis hsTKB2, produced extracellular alkaline (9–10.5), thermostable (50–80 °C), halophilic (0–30 %), organic solvent tolerant keratinolytic protease. The maximum enzyme production was observed in high alkaline condition (pH 10) at 45 °C in sea water as supporting medium and chicken feathers as substrate with cell-immobilization of chitin flakes. The molecular mass of purified enzyme was estimated to be about 59.89 kDa by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and MALDI-TOF analysis. The apparent Km for the enzyme activity on keratin was 1.9 mg mL−1. Optimum temperature and pH for keratinolytic protease activity were 70 °C and 10.5 respectively. The effect of organic solvents on the enzyme activity showed that this enzyme was more stable in the presence of non-polar organic solvents than polar solvents. Circular dichroism spectroscopy revealed that at pH 10.5 and temperature 70 °C, the enzyme upholds a typical secondary structure (α-helix 25.23 %, β-sheet 61.02 %, turn 11.97 % and coil 1.78 %). Mn2+ and toluene were influenced the enzyme activity by effecting structural changes. This enzyme folded into its active conformation inside the cell and secreted outside. Furthermore the tolerability with surfactants and commercial solid and liquid detergents appeared to be a favorable approach towards laundry and dishwashing detergents.

Enhancing the physicochemical and photophysical properties of small (<2.0 nm) CdSe nanoclusters for intracellular imaging applications

The chemical properties of surface passivating ligands that surround nanoclusters (NCs) are extremely important for controlling their structural, physicochemical, and photophysical properties. However, to investigate these properties in various environments, it is important to be able to dissolve the ligand-coated NCs in a wide range of polar and nonpolar solvents. We have developed a direct synthesis and purification procedure for poly(ethylene glycol) thiolate-protected ultra-small (<2.0 nm diameter) CdSe NCs, which have such solubility characteristics. These CdSe NCs were characterized by UV-vis absorption, photoluminescence, and X-ray photoelectron spectroscopy (XPS), as well as mass spectrometry. Analyses by XPS confirmed the formation of surface Cd-rich NCs and mass spectrometry confirmed a stoichiometric core with mass of 6.5 kDa. The NCs were synthesized in aqueous medium and purified using a simple solvent extraction method, and the organic phase-extracted CdSe NCs were readily soluble in a wide range of polar and nonpolar organic solvents including acetonitrile, ethanol, chlorobenzene, dichloromethane, and chloroform, as well as in water. The diverse solubility properties of poly(ethylene glycol) thiolate-protected ultra-small CdSe NCs allowed us to perform a post synthetic surface ligand treatment with triphenylphosphine in an organic solvent. The post synthetic treatment enhanced the photophysical properties of these ultrasmall NCs and resulted in an ∼8 fold increase in fluorescence quantum yield. These bright yellow, mixed ligand-coated CdSe NCs were then used for intracellular imaging studies for the first time due to their unique physicochemical properties. We also found that the penetration ability of mixed ligand-coated CdSe NCs through fibroblast cell membranes and the fluorescence properties of the NCs inside the cell were both strongly poly(ethylene glycol) chain length dependent.

The use of two non-toxic lipophilic oils to generate environmentally friendly anionic reverse micelles without cosurfactant. Comparison with the behavior found for traditional organic non-polar solvents

In this work two different non-toxic solvents/sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT)/water reverse micelles (RMs) have been investigated by dynamic (DLS) and static (SLS) light scattering techniques. Methyl laurate (ML) and isopropyl myristate (IPM) were used as external non-polar solvents to formulate the AOT RMs without cosurfactant. DLS results reveal the formation of IPM and ML AOT RMs containing water as a polar component since the droplet sizes values increase as the W0 values increase. To the best of our knowledge this is the first report where ML is used to formulate AOT RMs. The droplets size values, the maximum amount of water solubilized and the aggregation numbers (Nagg, determined by SLS) of both AOT RMs are dissimilar considering the chemical structure of the external solvents and they can be explained taking into account the different non-polar solvent penetration to the interface. The results suggest that IPM penetrate more the interface than ML in AOT RMs, diminishing the interdroplets interactions and producing RMs with smaller sizes and Nagg than ML/AOT. The higher viscosity and polarity of IPM in comparison with ML promotes the interface penetration. Thus, the penetration of IPM into the interface is higher than ML, making the interface of IPM/AOT RMs more rigid and, in consequence with smaller droplets sizes values. Finally, a peculiar comparable behavior (droplets size, maximum amount of water solubilized and Nagg) between n-heptane and ML AOT RMs and benzene and IPM AOT RMs was observed. These results present a very promissory field since that the unique properties of the alkanes/AOT/water RMs can be obtained using non-toxic lipophilic oils and, in the same way the opportunity to formulate environmentally friendly AOT RMs.

Cloning and characterization of newly isolated lipase from Enterobacter sp. Bn12.

A mesophilic Enterobacter sp. Bn12 producing an alkaline thermostable lipase was isolated from soil in Tehran, Iran. The lipase gene (ELBn12) was identified from a genomic library. Sequence analysis of the DNA fragment revealed an open reading frame of 879 bp encoding a lipase with a molecular mass of 31.3 kDa. The deduced amino acid sequence showed 96% identity with a lipase of Enterobacter sp. Ag1 and the identity of their DNA sequences was 88.9%. ELBn12 belongs to the lipase subfamily I.1 and its catalytic triad consists of Ser82, Asp237 and His259. The lipase was expressed in Escherichia coli (BL21) pLysS and partially purified by anion exchange chromatography. The maximum activity of ELBn12 was obtained at temperature of 60 °C and pH 8.0 towards tricaprylin (C8) and its specific activity was around 2900 U/mg. ELBn12 was stable within a broad pH range from 6.0 to 11.0. The enzyme showed high stability in both polar and nonpolar organic solvents at 50% (v/v). The lipase activity was enhanced in the presence of 10 mM of Ca(2+), Mg(2+) and K(+), while heavy metals (Fe(3+) and Zn(2+)) had strong inhibitory effect. ELBn12 showed high activity in the presence of 1% (w/v) nonionic surfactants, however ionic surfactants inhibited the lipolytic activity. ELBn12 characteristics show that it has a potential to be used in various industrial processes.

Distribution of Zinc and Cadmium in Tissues of Giant Reed (Arundo Donax L.): Sequential Extraction - Radiometric Study

Abstract Heavy metals are taken up by the vascular plant root system from water solutions in cationic forms. Subsequently, during both short and long distance transport to other plant tissues, cation forms are incorporated to many bioorganic compounds differing in stability, ionic character and physico-chemical properties such as solubility in lipid structures and mobility across cell membrane systems. Many sequential and single step extraction methods have been elaborated for characterization of the role of individual components of plant cells components in transport and detoxication of heavy metals. In our study, dry biomass of giant reed (Arundo donax L.) grown in hydroponic media spiked with 65ZnCl2 and 109CdCl2 was treated with dithizone solutions as complexing ligand in order to convert free Zn2+ and Cd2+ ions to corresponding dithizonates. Treatment with dithizone showed that up to 67 % of the total plant Cd and 56 % of the total plant Zn were transformed to dithizonate complexes extracted with chloroform. Extraction of biomass with Folch reagent showed that up to 48 % of the total root cadmium and up to 18 % of the total shoot cadmium is bound in lipid fraction. Zinc was not found in lipid fraction of root and shoot. Derivatization of the dried root and shoot lipid fraction by dithizone showed that two third of Cd in root and practically all Cd in shoot lipid fraction could be transformed to Cd-dithizonate. Methods of biomass treating with complexing ligands and a method of sequential extraction procedures with non-polar organic solvents and radiotracer methodology seem to be useful methods for the study of metal speciation and distribution in vascular plants

Investigation of thermodynamic and surface characterisation of 4-[4-(2-ethylhexyloxy)benzoyloxy]benzoic acid thermotropic liquid crystal by inverse gas chromatography

The inverse gas chromatography method was used to obtain thermodynamic and surface properties of the thermotropic liquid crystalline material, 4-[4-(2-ethylhexyloxy)benzoyloxy]benzoic acid (EBBA). The retention diagrams of undecane, dodecane, tridecane, ethyl acetate, n-butyl acetate, iso-butyl acetate, toluene, ethylbenzene, iso-propylbenzene, n-propylbenzene and chlorobenzene on EBBA were plotted at temperatures between 443.2 and 468.2 K. The specific retention volume, , Flory–Huggins interaction parameter, , equation-of-state interaction parameter, , and effective exchange energy parameter, , were determined. The dispersive component of the surface free energy, , of the studied adsorbent surface was estimated using retention times of different nonpolar organic solvents in the infinite dilution region. The specific free energy of adsorption, the enthalpy of adsorption, , and the entropy of adsorption, , of solvents on liquid crystal were determined. The values of were correlated with the donor and the acceptor numbers of the probes to quantify the acidic and the basic parameters of the liquid crystal surface. The values obtained for and parameters indicated an acidic character for the surface of EBBA.

A capacitive chemical sensor based on porous silicon for detection of polar and non-polar organic solvents

A capacitive sensor based on porous silicon (PSi) for detection of various polar (ethanol, methanol, acetone, acetonitrile, chloroform) and non-polar organic solvents (n-hexane, toluene) was described. The meso-PSi layer with an average pore size of 30 nm was prepared by a galvanostatic electrochemical etching of crystalline silicon in HF-based solution. Surface passivation was conducted by anodic oxidation process and the electrical contacts were made exclusively onto the front porous structure. The as-fabricated sensor exhibits highly sensitive and reversible response toward polar organic molecules during the real-time measurements of capacitance, whereas the capacitive sensing behavior was irreversible and opposite in direction in case of non-polar solvents. The response time was in the order of acetone < methanol < acetonitrile < ethanol < chloroform. The observed response could be understood as the impact of charge redistribution on the pore walls upon organic infiltration, along with changes in the dielectric constant of the porous layer. A comparative study of such different responses is provided. Excellent repeatability of the device was obtained after twelve cyclic tests of acetone, demonstrating stability of the sensor. Long-term stability for the sensor was also observed after four weeks storage. The present approach is useful for the development of a simple, cost-effective sensor for detection of various chemical analytes.

Conformational Behavior and Influence of Organic Solvents on a Strong Polar Group Nematogen at Room Temperature—A Computational Model

The conformational behavior and influence of organic solvents on a nematogen, 4’-n-alkyl-4-cyanobiphenyl, with strong polar group propyl (3CB) that is of commercial and application interest has been studied with respect to the translational and orientational motions. The atomic net charge and dipole moment components at each atomic center have been evaluated using the complete neglect differential overlap (CNDO/2) method. The modified Rayleigh-Schrodinger Perturbation theory with the multicentered-multipole expansion method has been employed to evaluate the long-range interactions, and a “6-exp.” potential function has been assumed for the short-range interactions. The minimum energy configurations obtained during the different modes of interactions have been taken as input to calculate the configurational probability using the Maxwell–Boltzmann formula in nonpolar organic solvents, i.e., carbon tetrachloride (CCl4), and chloroform (CHCl3) at room temperature 300 K. It has been observed that the molecules show the interesting property in the organic solvents. The interaction energies of dimer complexes have been taken into consideration in order to investigate the most energetically stable configuration. An attempt has been made to develop an interesting computational model for nematogen at molecular level.

Development of a PDMS-grafted alumina membrane and its evaluation as solvent resistant nanofiltration membrane

A new solvent resistant nanofiltration (SRNF) membrane is developed by grafting a PDMS polymer into the pores of a 5nm γ-alumina ceramic membrane. These PDMS-grafted γ-alumina membranes were attained through a two-step synthesis. The linking agent, 3-aminopropyltriethoxysilane (APTES), was first applied on a ceramic membrane either by a vapor phase or a solution phase method, followed by grafting of an epoxy-terminated PDMS. Through this route it was possible to tune the pore size and to engineer the surface chemistry (e.g. hydrophobicity) of ceramic membranes in favor of non-polar organic solvent permeation. Reproducible results were obtained for filtration experiments with hexane, toluene and isopropanol (IPA). As expected, higher permeabilities were found for non-polar solvents than for more polar solvents (resp. 4.8±0.1lm−2h−1bar−1 for hexane, 3.1±0.5lm−2h−1bar−1 for toluene and 0.54±0.04lm−2h−1bar−1 for IPA). A Molecular Weight Cut Off (MWCO) of 500±10Da was determined. Stability tests in hexane, toluene and IPA have shown that these newly developed membranes were stable in all these solvents during testing periods of up to 170 days.

Order–Disorder Phenomenon of Nematogens at Molecular Level—A Computational Approach

The phase behavior of nematogenic p-n-Alkoxy cinamic acids (nOCAC) with alkyl chain carbon atoms (n = 2,4) has been reported with respect to the translational and orientational motions. The atomic net charge and dipole moment components at each atomic center have been evaluated using the complete neglect differential overlap (CNDO/2) method. The modified Rayleigh-Schrodinger Perturbation theory with the multicentered-multipole expansion method has been employed to evaluate the long-range interactions, and a “6-exp.” potential function has been assumed for the short-range interactions. The minimum energy configurations obtained during the different modes of interactions have been taken as input to calculate the configurational probability using the Maxwell–Boltzmann formula in nonpolar organic solvents, i.e., carbon tetrachloride (CCl4), and chloroform (CHCl3) at room temperature 300 K. Further, entropy of each configuration has been computed. It has been observed that the molecules show the remarkable behavior in the solvents. An attempt has been made to develop new and interesting computational model for nematogens in the solvents and order–disorder phenomenon at molecular level.

The Interesting Property of Strong Polar Group Nematogens in Organic Solvents – A Computational Study

The interesting property of strong polar group nematogens, 4′-n-alkyl-4-cyanobiphenyl (nCB) with pentyl (5CB), and heptyl (7CB), groups that are of commercial and application interest has been studied with respect to the translational and orientational motions. The atomic net charge and dipole moment components at each atomic center have been evaluated using the complete neglect differential overlap (CNDO/2) method. The modified Rayleigh–Schrodinger Perturbation theory with the multicentered–multipole expansion method has been employed to evaluate the long-range interactions, and a “6-exp.” potential function has been assumed for the short-range interactions. The minimum energy configurations obtained during the different modes of interactions have been taken as input to calculate the configurational probability using the Maxwell-Boltzmann formula in nonpolar organic solvents, that is, carbon tetrachloride (CCl4), and chloroform (CHCl3) at room temperature 300 K. It has been observed that the molecules show the remarkable property in the organic solvents. The interaction energies of dimer complexes have been taken into consideration in order to investigate the most energetically stable configuration. An attempt has been made to develop a new and interesting model for nematogens at molecular level.