Liquid Chloroform Research Articles

Unraveling the Impact of Flexibility and Solvent Effects on the UV-Vis Absorption Spectrum of Subphthalocyanine in Liquid Chloroform within the Born-Oppenheimer Molecular Dynamics Approach.

A study based on Born-Oppenheimer molecular dynamics (BOMD) of the subphthalocyanine (SubPc) with a chloride attached to the central boron atom was carried out. The BOMD simulation is used to access the dynamic evolution of the SubPc in liquid chloroform, and the electronic absorption spectrum is calculated using the Time-Dependent Density Functional Theory (TDDFT) considering explicit solvent models. We show that the conformational changes and solvent effects produce a red shift of the Q-band, where the largest contribution is due to the geometry changes of the symmetric structure of SubPc. A large splitting (0.2 eV) of the first electronic transition is also described, and it originates as a shoulder in the Q-band, which according to previous experimental studies is attributed to a vibronic origin. The red shift is obtained in agreement with experiment within less than 0.1 eV. The splitting is a consequence of the symmetry breaking in the SubPc central ring structure occurring during the molecular dynamics, with a significant contribution to the large red shift and the broadening of the spectrum.

ONE POT DEVELOPMENT OF LIPID-BASED QUERCETIN SPHERICAL AGGLOMERATES FOR BIOAVAILABILITY ENHANCEMENT: IN VITRO AND IN VIVO ASSESSMENTS

Objective: Quercetin, a wonder flavanoid despite numerous pharmacological actions, has limited clinical applications due to solubility and permeability issues and additionally having shorter biological half-life. The goal of the current work was to design Quercetin lipid-based spherical crystals, to improve its oral bioavailability and sustain its in vivo plasma levels. Methods: An anti-solvent precipitation method was employed to prepare quercetin spherical agglomerates using ethanol and distilled water as good and bad solvents, respectively. As bridging liquid chloroform, dichloromethane, hexane and gelucire 43/01, compritol 888 as lipid carrier were screened. The drug-to-lipid polymer proportion and stirring speed effect were optimized by 3-level, 2-factor, experimental design. Numerical optimization function was employed to identify the optimum level of independent variables. Spectroscopic, micromeritic, surface morphology, size distribution, saturated solubility, in vitro dissolution, in vivo pharmackokinetic and stability studies were performed. Results: Surface morphology studies indicated the agglomeration of quercetin needle-like fragments into a spherical shape, which further showed smooth surfaces due to entrapment of QC in lipid carrier. The spherical agglomerates of quercetin showed a four-fold improvement in aqueous solubility compared to pure drug and showed 92.13% release in 8 h. The optimised formulation showed a 3.69-fold enhancement in relative bioavailability in contrast to the marketed preparation in an in vivo pharmacokinetic analysis in male Wistar rats. Conclusion: The obtained lipid-based spherical crystals of quercetin with enhanced bioavailability could be effectively used for its various potential pharmacological applications. The designed system can also be utilized to deliver other phytochemicals with poor bioavailability due to limited solubility and permeability.

Femtosecond coherent anti-Stokes Raman spectroscopy study of vibrational dynamics of liquid chloroform.

Femtosecond time-resolved coherent anti-Stokes Raman spectroscopy (CARS) was used to study the dynamics of the vibrational modes of liquid chloroform. The vibrational modes were selectively excited and their coherent vibrational dynamics were obtained. Some subtle features that are difficult to distinguish in the ordinary spontaneous Raman spectrum, such as overtones and combinations of some fundamental vibrational modes, were recognized from the CARS transients. Combined with theoretical calculations, the contributions of chlorine isotopes were also confirmed from the CARS transients of the vibrational modes involving the motion of chlorine atoms.

Theoretical Investigation of Mid Infrared Temperature Sensor Based on Sagnac Interferometer Using Chloroform Filled Photonic Crystal Fiber

In this paper, a novel Sagnac Interferometer (SI) based chalcogenide Photonic Crystal Fiber (PCF) temperature sensor is theoretically and numerically analyzed operating in the mid infrared (MIR) region. The PCF cladding air holes are proposed to be filled with a highly temperature sensitive liquid chloroform to enhance the temperature sensitivity. The temperature sensing characteristics of three different infiltration technique is investigated theoretically and compared by Finite Element Method (FEM). Simulation results show that full infiltration performs better than partial infiltration. In the numerical analysis two sensing dips with high linearity is achieved for full infiltration which shows sensitivity of −5.77 nm/°C and 8.49 nm/°C when the temperature increases from 25 to 85 °C for the specific fiber length of 1.532 mm. The R <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> values are 0.957446809 and 0.97680771 for the respective two sensing dips. The proposed highly sensitive sensor has broad detection window which can be applied in fingerprint unlocking, MIR radiation detection in human body, biomedicine applications, and environmental temperature monitoring.

Self-aggregation of stilbazolium ion pairs in liquid chloroform. A molecular dynamics study

Molecular aggregation plays an important role on optical phenomena, and optimizing the latter requires understanding the aggregation behavior as a function of the molecular structures. The formation of molecular aggregates composed of stilbazolium chromophores and small to medium-size anions is studied by carrying out classical molecular dynamics (MD) simulations, shedding light on the dynamics of spontaneous self-aggregation of anion-cation (AC) pairs and estimating their equilibrium aggregation constants. First, analyses based on atom-atom distances and on contact mapping (Voronoi tessellation) highlight that the interactions occur at the level of the methylpyridinium groups of the cations, which enabled monitoring the clustering dynamics. Then, simulations show that clusters containing up to 5 AC pairs dominate the populations. Among the AC pairs, two of them (where the stilbazolium bears a strong donor substituent and when the anion is SCN- or pTS-) aggregate into small clusters even at high concentration, corroborating related experimental results [ChemPhysChem. 11 (2010) 495–507]. Still, these MD simulations do not reveal strict relationships between the aggregate size and the nature of the anion. Nevertheless, AC pairs bearing iodide anions require longer MD simulation times to reach an asymptotic equilibrium tendency of the average number of clusters. Finally, the aggregates are shown to adopt a preferential Λ-shape with contributions from head-to-head and stacked forms. Complementarily, the analyses of the isoperimetric quotient reinforce the AC pairs are not forming spherical aggregates even for clusters including more than 10 AC pairs. So, when the stilbazolium bears a strong donor substituent and when the anion is pTS-, stacked aggregates are formed, at both low and high concentrations, resulting in excellent agreement with the measured aggregation equilibrium constant.

Thermochemistry of solution of methylpheophorbide a, dioxidine and their conjugate in chloroform from 298.15 K to 318.15 K

This paper focuses on the study of thermochemistry of solution and transfer of potential hydrophobic photosensitizers, viz. 9-ethenyl-14-ethyl-21-(methoxycarbonyl)-3-{(O-methylcarbamoyl)ethyl}-4,8,13,18-tetramethyl-20-oxo-phorbine (Methylpheophorbide a, comp. 1), [3-(hydroxymethyl)-1-oxido-4-oxoquinoxalin-4-ium-2-yl]methanol (Dioxidine, comp. 2) and their conjugate 9-ethenyl-14-ethyl-3-{[2-(3-hydroxymethyl)]-1-oxido-4-oxoquinoxalin-4-ium-2-methyleneoxy}carbamoyl}ethyl)-4,8,13,18-tetramethyl-20-oxo-phorbine (Conjugate, comp. 3), in liquid chloroform (CHCl3) and N,N-dimethylformamide (DMF) between the temperatures of 298.15 K and 318.15 K. The standard enthalpies and heat capacities of solution as well as partial molar heat capacities of these species and some non-electrolytes modeling their side-chains have been computed from experimental enthalpies of solution and compared with previously reported quantities to highlight several important features of solvation of potential drugs in H-donor and H-acceptor media.

Mixing dynamics of diethyl ether and chloroform

Mixing dynamics of liquid diethyl ether and chloroform were studied by time-resolved Fourier-transform infrared absorption spectroscopy in attenuated total reflectance mode (ATR-FTIR). An in situ experiment where chemicals were mixing in the vertical cell directly attached to the diamond ATR accessory was carried out. The data were analyzed by two-dimensional correlation spectroscopy (2D COS) and multivariate curve resolution (MCR). The analysis of ATR-FTIR spectra has shown that each species (diethyl ether and chloroform) exist in an unbound (free) state and bound state (as a part of the molecular complex). The concentration and spectral profiles of mixture components were obtained using MCR decomposition. A theory of nonlinear diffusion has been used to model the experimentally obtained concentration profiles. It has been shown that the theoretical concentration profiles are in good qualitative agreement with experimental ones.

Deconstructing the Local Intermolecular Ordering and Dynamics of Liquid Chloroform and Bromoform.

Local intermolecular structure and dynamics of the polar molecular liquids chloroform and bromoform are studied by molecular dynamics simulation. Structural distribution functions, including 1- and 2-D pair correlations and dipole contour plots allow direct comparison and show agreement with recent analyses of diffraction experiments. Studies of the haloforms' reorientational dynamics and longevity of structural features resulting from intermolecular interaction extend previous work toward deeper understanding of the factors controlling these features. Analyses of ensemble average structures and dynamical properties isolate mass, electrostatics, and steric packing as driving forces or contributing factors for the observed ordering and dynamics.

English

The extraction of high-quality DNA from okra (Abelmoschus esculentus L. Moench) is notoriously troublesome due to the high contents of polysaccharides, polyphenols, and different secondary metabolites. We have tested seven extraction buffers on silica dried okra leaves. Here, we describe a simple, rapid and modified procedure for high-quality DNA extraction from okra, which is amenable for downstream analyses. In contrast to Cetyl-trimethyl-ammonium bromide (CTAB) methods, the described procedure is rapid, omits the use of liquid nitrogen, phenol, PVP-10, and chloroform. It also uses inexpensive and less hazardous reagents and requires only ordinary laboratory equipment. The procedure employed a high concentration of Sodium dodecyl sulphate (SDS) to rid the problems associated with polysaccharides and polyphenols. The average yield was between 36 and 45 &mu;g of total DNA from 90 mg of dried leaf weight. The DNA is adequate for molecular analysis of okra, such as genetic mapping or marker-assisted plant breeding. This protocol can be performed in as little as 3 h and may be adapted to high-throughput DNA isolation. &nbsp; Key words: PVP-10, polyvinylpyrrolidone, non cetyltrimethylammonium bromide, okra, genomic DNA, Sodium dodecyl sulphate (SDS).

Comparative Study on Soil Microbial Biomass in Tarai and Hill Sal (Shorearobusta Gaertn.) Forests of Tropical Region in Eastern Nepal

A comparative study was conducted to investigate the effect of altitudinal variation and seasonality on soil microbial biomass carbon (MB-C), nitrogen (MB-N), and phosphorus (MB-P) between Tarai Sal forest (TSF) and Hill Sal forest (HSF) of the tropical region in eastern Nepal. Soil microbial biomass was estimated by chloroform fumigation - extraction method in summer, rainy and winter seasons in the upper (0-15 cm) soil depth in both forests. Pre-conditioned soil samples were saturated with purified liquid chloroform, represented fumigated sample. Another set of soil samples without using chloroform, represented unfumigated samples and soil biomass was estimated from these samples. MB-C, MB-N, and MB-P were higher by 66%, 31%, and 9%, respectively, in HSF than TSF. Distinct seasonality was observed in soil microbial biomass. It was maximum in summer and minimum in rainy season in both the forest stands. The value decreased from summer to rainy season by 46 to 67% in HSF and by 32 to 80% in TSF. Higher soil microbial biomass in the summer season may be due to its accumulation in soil when the plant growth and nutrient demand are minimal. Analysis of variance suggested that MB-C, MB-N, and MB-P were significantly different for both sites and seasons (P &lt; 0.001). Soil organic carbon, TN, and TP were positively correlated with MB-C, MB-N, and MB-P in both the forests. In conclusion, the higher value of soil microbial biomass in HSF may be due to the higher concentration of soil organic matter and decreasing turnover rate of microbial biomass due to higher altitude. On the other hand, the lower value of microbial biomass at TSF may indicate its fast turnover rate due to lowland tropics to enhance the nutrient cycling process.

Growth Kinetics of Single Crystalline C8-BTBT Rods via Solvent Vapor Annealing

The successful device fabrication of organic semiconducting single crystals relies on controlling their growth properties, which can only be achieved by understanding the growth kinetics of the crystals under various growth conditions. Here, we measure the growth kinetics of single crystalline 2,7-dioctyl[1] benzothieno­[3,2-b]­[1]­benzothiophene (C8-BTBT) rods on poly­(methyl methacrylate) (PMMA) films at various substrate temperatures (Tsub) and chloroform gas pressures (Pchl) during solvent vapor annealing using in situ optical microscopy. Initially, the total volume of the rods quickly increases, but afterward, the volume splits into three different modes depending on the parameters: (mode 1) remaining constant at high Tsub and low Pchl, (mode 2) slowly decreasing at medium Tsub and Pchl (i.e., 28 °C and 220 Torr), and (mode 3) rapidly decreasing at low Tsub and high Pchl. These behaviors are explained by the competition between the adsorption and desorption of chloroform molecules on the PMMA film. With decreasing Tsub and increasing Pchl, the number of molecules adsorbed on the film increases with time, allowing the rods to be dissolved into chloroform. For the opposite conditions, the molecules are evaporated, thereby preventing the coarsening of the rods. Interestingly, during growth, each rod is encapsulated in a liquid chloroform drop, and the rods only interact when they are trapped in a liquid chloroform drop via the coarsening of multiple liquid drops. Additionally, we demonstrate the successful application of the rods grown at the mode 2, the best SVA condition, to field effect transistors (FETs), obtaining the hole mobility of 7.67 cm2/(V s), comparable to that of the best single crystal organic FET.

Liquid-Filled Highly Asymmetric Photonic Crystal Fiber Sagnac Interferometer Temperature Sensor

In this paper, we theoretically designed and numerically studied a high-resolution and ultrasensitive photonic crystal fiber temperature sensor by selective filling of a liquid with high thermo-optic coefficient in one of the airholes of the fiber. The finite element method was utilized to study the propagation characteristics and the modal birefringence of the fiber under different ambient temperatures. A large base birefringence value of 7.7 × 10−4 as well as a large birefringence sensitivity of almost 29% to a 10 °C temperature variation was achieved for the optimized fiber design with liquid chloroform between 15 °C and 35 °C. We also studied the performance of the proposed optical fiber in a temperature sensing Sagnac interferometer. An average linear temperature sensitivity of 17.53 nm/°C with an average resolution of 5.7 × 10−4 °C was achieved over a temperature range of 20 °C (15 °C to 35 °C).

Hydrophobic boron organic polymers: Ultra-high capacity of enrichment and storage for chloroform

Chloroform, a superstar widely applied as solvent, extractant, refrigerating fluid and adhesive, faces storage risks and environmental pressures. Herein, a brand-new strategy for storing and enriching chloroform is designed. It is shown that stable boron organic polymers BOPs-S3 with excellent hydrophobicity can be facilely prepared by combining Na2[B12H12] and amphiphilic HBPB-14 molecules. The unique molecular structure of such as prepared polymers endows strong affinity with chloroform. BOPs-S3 possesses an ultra-high adsorption capacity of 46.9 g·g−1 toward liquid chloroform, with a resulting gel that maintains a low volatilization rate. In addition, a stainless mesh coating with BOPs-S3 is shown to excellently remove chloroform vapor, likewise BOPs-S3 is shown efficient for removal of chloroform traces in water, with a residual amount lower than the allowable concentration in drinking water defined by the World Health Organization. This work provides a novel approach to store chloroform in transportation or other unstable conditions with unprecedented ramifications.

Local structure and orientational ordering in liquid bromoform

The neutron diffraction data of liquid bromoform (CHBr3) at 25°C was analysed using the Empirical Potential Structure Refinement technique in combination with H/D isotopic substitution. Compared to liquid chloroform (CHCl3), CHBr3 displays more spatially defined intermolecular contacts. A preference for polar stacking with collinear alignment of dipole moments is observed for the most closely approaching CHBr3 molecules, although to a lesser extent than in chloroform. Consistent with this, and in line with dielectric spectroscopy, the Kirkwood correlation factor from the structural model of CHBr3 is smaller than that of CHCl3. The net antiparallel alignment of dipole moments in CHBr3, as suggested by dielectric spectroscopy, must be due to weak but persistent long-range orientation correlations in CHBr3, which counteract the local polar stacking.

In English

The aim of this study was to analyze the temperature and interfacial behavior of water bound to A-300, A-300/AM1 and Al 2 O 3 /AM1 initial and mechanically treated and located in air, chloroform alone or with addition of trifluoroacetic acid (TFAA) using low-temperature 1 H NMR spectroscopy and cryoporometry. Properties of unmodified (A-300) and modified (AM1) (1 : 1) nanosilicas, as well as nanoalumina, were studied in air or chloroform alone or with addition of TFAA using 1 H NMR spectra recorded at different temperatures and related cryoporometry. In nontreated composite, water interaction with nanosilica (hydration degree h = 1.125 g/g) increases and free surface energy g S grows by five times due to water reorganization into nanoclusters and similar clusters are absent in cA-300 due to several factors. After the mechanical treatment (bulk density increases to r b » 1.2 g/cm 3 ), water interaction energy with nanosilicas becomes smaller (by three times for CDCl 3 and ten times for air medium) than that for nontreated composite. The effects of CDCl 3 are much stronger for water in nontreated system than those in compacted composite. This is due to reorganization of water affected both by changes in the confined space effects and the influence of hydrophobic chloroform, which can displace water into small voids (inaccessible for larger chloroform molecules) or larger voids to reduce the contact area of both liquids. Thus, it has been shown that the observed influence of the hydrophobic components in complex hydrophobic/hydrophilic systems on enhancement of water binding to hydrophilic components is the general phenomenon caused by both the confined space effects and features of interactions of water with various hydrophobic structures such as the surface functionalities of hydrophobic silica and hydrophobic liquid (chloroform) or proton-donor components (TFAA).

On the local intermolecular ordering and dynamics of liquid chloroform

Recently published neutron scattering experiments suggest local molecular ‘polar stacking’ in bulk liquid chloroform. We present molecular dynamics simulations of liquid chloroform that confirm the existence of these structures in relative populations that agree with experiment. Removing the electrostatic contributions to the chloroform force field leaves these structures mostly unchanged. Dynamic studies show that the lifetimes of these short-lived structures are also unchanged when disabling electrostatics. This set of results confirms that these polar-stacked structures are the result of geometrical packing, as opposed to dipole-dipole interactions or other electrostatic driving forces. We also extend this investigation of local intermolecular ordering in chloroform to relate these polar stacking populations to the well-known ‘Apollo configuration,’ where nearby molecules have collinear, head-to tail-dipole moment vectors. We find that the ‘Apollo configuration’ represents only a very small fraction of the total population in bulk liquid CHCl3.

A Series of Robust Copper-Based Triazolyl Isophthalate MOFs: Impact of Linker Functionalization on Gas Sorption and Catalytic Activity †.

The synthesis and characterization of an isomorphous series of copper-containing microporous metal-organic frameworks (MOFs) based on triazolyl isophthalate linkers with the general formula [Cu4(μ3-OH)2(R1-R2-trz-ia)3(H2O)x] are presented. Through size adjustment of the alkyl substituents R1 and/or R2 at the linker, the impact of linker functionalization on structure-property relationships was studied. Due to the arrangement of the substituents towards the cavities, the porosity (pore fraction 28%–39%), as well as the pore size can be adjusted by the size of the substituents of the triazole ring. Thermal analysis and temperature-dependent PXRD studies reveal a thermal stability of the MOFs up to 230 °C due to increasing framework stability through fine-tuning of the linker substitution pattern. Adsorption of CO2 (298 K) shows a decreasing maximum loading with increasing steric demand of the substituents of the triazole ring. Furthermore, the selective oxidation of cyclohexene with tert-butyl hydroperoxide (TBHP) is studied over the MOFs at 323 K in liquid chloroform. The catalytic activity increases with the steric demand of the substituents. Additionally, these isomorphous MOFs exhibit considerable robustness under oxidizing conditions confirmed by CO2 adsorption studies, as well as by the catalytic selective oxidation experiments.

Numerical simulation of coherent visible-to-near-infrared supercontinuum generation in the CHCl3-filled photonic crystal fiber with 1.06 μm pump pulses

The hollow-core photonic crystal fiber (PCF) is filled by highly nonlinear liquid chloroform (CHCl3) in the center core. The CHCl3-filled PCF with an appropriate geometric parameters exhibits a normal dispersion profile in the visible-to-near-infrared (NIR) region, where the values of group velocity dispersion (GVD) in the vicinity of 1060-nm pump wavelength can be tuned in the range from −20 to −50ps/nm/km. Furthermore, the nonlinear parameters at wavelengths <1100nm are higher than 0.7W−1m−1, which can lead to a significant enhancement of the spectral broadening, especially on the blue side. The numerical results show that, when 100-fs pulses centered at 1060nm are launched in the 0.01m-long fiber (47kW peak power), the generated supercontinuum (SC) spectra with high degree of coherence can cover near 2 octaves spanning from 340 to 1360nm at −20dB level. The spectral variations are < 5dB in the wavelength range of 365–1315nm.

Chemical transformations of liquid chloroform, hexane, and heptane in microwave plasmoid field

Yields of the products of the microwave plasmoid treatment of liquid n-hexane, n-heptane, or chloroform and their mixtures have been measured using the gas chromatography—mass spectrometry technique.

Multiscale computational modeling of (13)C DNP in liquids.

Dynamic nuclear polarization (DNP) enables the substantial enhancement of the NMR signal intensity in liquids. While proton DNP is dominated by the dipolar interaction between the electron and nuclear spins, the Fermi contact (scalar) interaction is equally important for heavier nuclei. The impossibility to predict the magnitude and field dependence of the scalar contribution hampers the application of high-field DNP to nuclei other than (1)H. We demonstrate that molecular dynamics (MD) simulations followed by density functional calculations of the Fermi contacts along the MD trajectory lead to quantitative agreement with the DNP coupling factors of the methyl and carbonyl carbons of acetone in water at 0.35 T. Thus, the accurate calculation of scalar-dominated DNP enhancement at a desired magnetic field is demonstrated for the first time. For liquid chloroform at fields above 9 T, our methodology predicts direct (13)C DNP enhancements that are two orders of magnitude larger than those of (1)H.