Preparation of Langmuir-Blodgett Film of Oligophenylenevinylene at the Air/Water Interface and Study on its Fluorescence

Phenylenevinylene polymers and oligomers were widely investigated as active materialsused in emission layer of light emitting diodes (LEDs), recently, due to their conductingand luminescent properties1-3. Comparing with their polymers, oligophenyl ene-vin…     

A Spectrometric Setup for Synchronous Total Internal Reflection Fluorescence Measurement at the Solid／Liquid Interface

A spectrometric setup of perform total internal reflection fluorescence(TIRF) and synchronous TIRF measurements at solid/liquid interfaces is presented. The combination of TIRF and synchronous fluorescence was proposed to analyze simultaneously different components at interfaces. The TIRF excitation,emission and synchronous spectra of a water-soluble porphyrin were obtained from water/glass interface using this setup without the existence of a surfactant.     

A Solid Ag Film Deposited from Solution on Self—assembled Mercaptopropyltrimethoxysilane （MPTS） Monolayer

Mercaptopropyltrimethoxysilane (MPTS) bearing mercapto groups was used to form self-assembly monolayers (SAMs) on glass substrates by solution extraction.SEM,XRD and rubbing test analysis illustrated that the Ag film on the SAMs-modified glass was more durable than that on the commonly-modified glass and that the crystallinity of Ag film on the SAMs-modified glass was identical with those of the Ag film on the commonly-modified glass and pure Ag.     

Interaction between Sulfaproxyline and β-Cyclodextrin in the Solution and Solid States

The 1 : 1 inclusion complex between sulfaproxyline (SP) and -cyclodextrin (-CD) was prepared by the freeze-drying and the kneading method. Complex formation was confirmed in the solid state by X-ray diffractometry and by infrared spectroscopy. The interaction between sulfaproxyline and -cyclodextrin in solution was studied by the solubility method and 13C-NMR spectroscopy. Phase solubility studies in water revealed a AN type diagram and a stability constant of 930 ± 120 M-1 for a 1 : 1 inclusion complex was derived. Complexation was found to improve the dissolution rate of sulfaproxyline.     

Inclusion Complexation of Carbaryl and β-Cyclodextrin in Solution and in the Solid State

This study was carried out with the aim ofinvestigating the interactions between-cyclodextrin and carbaryl, a carbamatepesticide, and their effect on some physico-chemicalproperties of carbaryl, such as aqueous solubility andlipophilicity. The interactions between carbaryl and-cyclodextrin were thoroughly investigated bothin solution and in the solid state. The effect of-cyclodextrin on the aqueous solubility ofcarbaryl was evaluated by the phase solubility method.The amount of carbaryl dissolved increased linearlywith the addition of -cyclodextrin according toan A_L type plot and without precipitation of thecomplex. The apparent stability constant of thecomplex was 289 ± 21 M^-1, assuming a 1 : 1stoichiometry; this value was confirmed by a methodbased on circular dichroism measurements.Equimolar carbaryl/-cyclodextrin solid systemswere prepared by physical-mixing and freeze-drying,and fully characterised by Differential ScanningCalorimetry, X-ray powder diffractometry and FourierTransform Infra-Red analysis. The results of the solidstate study demonstrated that the freeze-drying methodyields a system with a high degree of amorphisationand yields an inclusion complex.The dissolution profile of the pesticide was affectedby the physico-chemical properties of each solidsystem, the freeze-dried form dissolving more rapidly. However, the physical association of-cyclodextrin and carbaryl enhanced the aqueoussolubility of the insecticide as well.     

Light-Induced Charge Transfer at Interface Between Lipid-Free RhTSPc Film and p-Si(111)

The present paper covers the lipid-free rhodium tetrasulfonato-phthalocyanine (RhTSPc) films prepared on p-Si(111) by using Langmuir-Blodgett technique. Their surface photovoltage spectra were measured. It was found that there is a strong interaction at the interface between the RhTSPc film and p-Si (111) and that the surface photovoltaic effect of the film system is maximum when only one monolayer of RhTSPc molecules coats p-Si(111), which is similar to that of CuTSPc films on p-Si(111) reported previously. These results confirm that only the monolayer of dye molecules being adjacent to the semiconductor surface plays a key role in the light-induced interfacial charge transfer process.     

Synthesis of New Multibranch Chromophores with Strong Light-emitting in Solution and in PMMA Film

Three new chromophores with triphenylamine as molecular focal point bearing one,two, or three 4-(n-butyloxystyryl) group(s) at the periphery respectively, (named as T1, T2, and T3) have been synthesized and characterized. It is interesting to find that the fluorescence quantum yield increases from T1 (0.489), to T3 (0.535), and to T2 (0.628) in cyclohexane, meanwhile the lifetime for T3 is shorter than T1 and T2, which is an important characteristic for applications in light emitting diode. Also PMMA (polymethyl methacrylate) film doped with T3 gives stronger fluorescence than T1, and T2. Cyclic voltammetry showed that T3 exhibited lowest oxidation potential of-0.52 V vs SCE, suggesting its better hole-transport property.     

Transformation of an Imine Cage to a Covalent Organic Framework Film at the Liquid–Liquid Interface

Dynamic covalent chemistry (DCC) opens up a fascinating route for the construction of well-organized supramolecular architectures, starting from organic molecular cages to crystalline macromolecular covalent organic frameworks (COFs). Herein, for the first time, we have manifested a facile room-temperature DCC-directed transformation of discrete organic imine cage-to-COF film at the liquid–liquid interface. The unfolding of the cage leading to the generation of imine intermediates, followed by their interface-assisted preorganization and subsequent growth of the COF film, are elucidated through detailed spectroscopic and microscopic investigations. The interfacial cage-to-COF transformation provides a facile route for the faster fabrication of free-standing COF films with high porosity and crystallinity, demonstrating excellent performance towards molecular sieving and high solvent permeance. Thus, the current study opens up a new route for structural interconversion between two crystalline entities with diverse dimensionality employing DCC at the confined interface.     

The Equilibria of Phosphatidylethanolamine-Cholesterol and Phosphatidylcholine–Phosphatidylethanolamine in Monolayers at the Air/Water Interface

Monolayers of phosphatidylethanolamine (PE), cholesterol (Ch), phosphatidylcholine (PC), and binary mixtures (PC-PE or PE-Ch) were investigated at the air/water interface. The surface tension values of pure and mixed monolayers were used to calculate π -A isotherms. The surface tension measurements were carried out at 20°C using an improved Teflon trough and a Nima 9000 tensiometer. The Teflon trough was filled with a subphase of triple-distilled water. Known amounts of lipid dissolved in 1-chloropropane were placed at the surface using a syringe. The interactions between phosphatidylethanolamine and cholesterol as well as phosphatidylcholine and phosphatidylethanolamine result in significant deviations from the additivity rule. An equilibrium theory to describe the behavior of monolayer components at the air/water interface was developed in order to obtain the stability constants of PC-PE and PE-Ch complexes. We considered the equilibrium between the individual components and the complex and established that phosphatidylethanolamine and cholesterol as well as phosphatidylcholine and phosphatidylethanolamine formed highly stable 1:1 complexes.     

A New [5]Ferrocenophane Containing a N–Si–O–Si–N Bridge. Molecular Structure in the Solid State and in Solution

The reaction of 1,1-diaminoferrocene 1 with 1,3-dichloro-1,1,3,3-tetramethyl-1,3-disiloxane in the presence of triethylamine gave the new 1,5,3,2,4-diazaoxadisila[5]ferrocenophane, which was characterized in the solid state by X-ray structural analysis, ¹³C and ²⁹Si MAS NMR spectroscopy, and in solution by [¹H], [¹³C], [¹⁵N], and [²⁹Si]NMR spectroscopy. The ideal ferrocene geometry is slightly distorted, and the cycle containing the heteroelements N, Si, and O is nonplanar. In solution, NMR spectra indicate dynamic processes which may involve both the cyclopentadienyl rings and ring inversion.     

Pseudorotaxanes of β-Cyclodextrin with Diamino End-functionalized Oligo-phenyl and -benzyl Compounds in Solution and in the Solid State

-Cyclodextrin forms a 1:1 host:guest inclusion complex ([2]pseudorotaxane) with 4-[2-(4-aminophenyl)ethyl]-benzenamine (1) in water as determined by 1D and 2D NMRexperiments. In the crystalline state, the structure of the complex has revealed a 2:2 stoichiometry, with two CD molecules forming head-to-head dimers byH-bonds between the secondary O3 hydroxyl groups and enclosing two molecules of the guest. The packing mode of the present complex is encountered for the first time, since it does not belong to any of the four known packing types of the dimeric CD inclusion complexes. On the other hand,N ¹,N ⁴-bis(4-aminophenyl)-1,4-benzenedimethanamine 2), which is longer than 1 by a phenylene diamine unit, has not afforded any crystals, at present, however it threads into CD in aqueous solution forming most probably [2]- and [3]pseudorotaxanes. The solution structures and the equilibria in this system are investigated.     

Conformational Heterogeneity of a Tripeptide in the Solid State and in Solution: Characterization of a γ-Turn Containing Incipient Hairpin in Solution

A terminally blocked tripeptide Boc--Ala-Aib--Ala-OMe 1 with noncoded amino acids forms a novel type of hairpin structure containing a -turn instead of a conventional -turn in the central loop region in solution. This new type structural motif was characterized by NMR and restraint molecular dynamics simulation study. In the solid state peptide 1 adopts an extended backbone conformation and self-assembles to form supramolecular -sheet.     

A Solution and Solid State Study on 2-Hydroxypropyl-β-Cyclodextrin Complexation with Hyodeoxycholic Acid

Hyodeoxycholic acid (HDCA) isa 6- dihydroxylated natural bile acid capable ofpreventing gallstone formation by reducing the bilecholesterol saturation. However, any attempt to enrichthe bile acid pool with HDCA have failed owing to thepoor solubility of the molecule. To resolve thebioavailability problems, the complexation of HDCAinto the HPCD cavity was studied in solution(solubility methods, ¹³C- and ¹H-NMRspectroscopy and circular dichroism) and in the solidstate (IR spectroscopy, X-ray diffractometry andthermal analysis). According to the results, the HDCAinclusion took place with 1 : 1 stoichiometry. Theinfluence of different preparation methods of thesolid complex was evaluated for its potential use inappropriate pharmaceutical formulations to improve thebioavailability of HDCA.     

Stability Constants and Fluorescence of Terbium(Ⅲ) Complexes with Polyaminopolycarboxylates in Aqueous Solution

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Studies on Lattice Parameter,Molar Volume and Excess Molar Volume of Pb-based a-phase Solid Solution in Pb-Sn-Cd Ternary System

The lattice parameters a and the molar volumes Km of Pb-based a-phase solid solutions in the Pb-Sn-Cd ternary system were determined by means of X-ray diffraction. The lattice parameters a vary linearly with the molar fractions, the molar volumes show a positive deviation from the ideal solution behaviour, and the contribution of the solute Cd to the excess molar volumes V is much larger than that of the solute Sn. According to Vegard' s law orsub-regular solution model, the relationship between the experimental data of a or Vm andthe compositions of alloy is obtained by the mathematic regressive method, the prediction precisions of the both formulae are within the limits of experiment error.     

Intermolecular Magnetic Spin–Spin Interactions in Solution State at 1.53 mT

Overhauser dynamic nuclear polarization (DNP) technique can provide a dramatic increase in the signal obtained from nuclear magnetic resonance experiments owing to the magnetic spin–spin interactions between ¹H nuclei of the solvent and electrons delocalized on the asphaltene in crude petroleum or asphalt. Studies on ¹H Overhauser DNP enhancements at 1.53 mT are reported for benzene solvent medium with three different radical sources: Iran crude petroleum, MC30 liquid asphalt, and MC800 liquid asphalt for a range of radical concentrations. The results show that protons of benzene are good detectors for dipolar coupling.     

Comparison of Modifiers for Mercury Speciation in Water by Solid Phase Extraction and High Performance Liquid Chromatography–Atomic Fluorescence Spectrometry

Diethyldithiocarbamate and 2-mercaptoethanol modifiers were compared for the preconcentration of mercury species in water by C₁₈ solid phase extraction (SPE). The recovery values of mercury species were determined by high performance liquid chromatography–atomic fluorescence spectrometry. The eluent type, pH, chloride ion concentration, humic acid concentration, and storage time were evaluated to compare the preconcentration efficiency. L-cysteine was employed to elute the mercury compounds. Less eluent was needed for 2-mercaptoethanol modified SPE than for diethyldithiocarbamate modified SPE at an L-cysteine concentration of 0.12%. Diethyldithiocarbamate modified SPE could be used over a wider pH range and higher humic acid concentrations, whereas 2-mercaptoethanol modified SPE was less affected by the chloride concentration. Both modified SPE systems stored mercury species for 5 days, but diethyldithiocarbamate modified SPE could be stored longer. Diethyldithiocarbamate SPE provided limits of detections of 3.5, 2.5, and 4 ng · L^?1 and average recoveries of 90.78 ± 3.37%, 96.79 ± 5.12%, and 84.88 ± 5.37% for mercury(II), methylmercury, and ethylmercury, respectively. The relative standard deviation was less 6.5%. For 2-mercaptoethanol modified SPE, the limits of detection were 1.4, 1, and 1.6 ng · L^?1 and the recoveries were of 87.66 ± 8.45%, 86.70 ± 2.61%, and 91.31 ± 6.98% for mercury(II), methylmercury, and ethylmercury, respectively, with a relative standard deviation below 9.7%. Water should be characterized for its physical and chemical characteristics before mercury preconcentration to choose the most suitable method.     

A Calorimeter for Measuring the Enthalpy of Solution of Solid Solutes in Supercritical Fluids and Study on CO_2-Naphthlene System

Supercritical fluids (SCFs) have some unique properties1 It has been known that SCFs have very strong ability to dissolve low volatile compounds, which is the basis of SCF technology. However, the mechanism of SCFs to dissolve solutes is not very clear. Enthalpy of solution of solutes in SCFs can provide useful information for studying the mechanism. In this work, we built a calorimeter and ΔH for the dissolution of naphthalene in supercritical CO2 was determined. This kind of work wa…     

Solid–liquid equilibria in the NaCl–SrCl2–H2O system at 288.15 K

The phase equilibria in the ternary system NaCl–SrCl₂–H₂O at 288.15 K were studied with the isothermal equilibrium solution method. The phase diagram and refractive index diagram were plotted for this system at 288.15 K. The phase diagram contains one invariant solubility point, two univariant solubility curves, and two crystallization fields of NaCl and SrCl₂ · 6H₂O. The refractive indices of the equilibrium solution change regularly with w(NaCl) increase. The calculated refractive index data are in good agreement with the experimental data. Combining the experimental solubility data of the ternary system, the Pitzer binary parameters for NaCl at 288.15 K and SrCl₂ at 298.15 K, the Pitzer mixing parameters θ_{Na, Sr}, Ψ_{Na, Sr, Cl} and the solubility equilibrium constants Ksp of solid phases existing in the ternary system at 288.15 K were fitted using the Pitzer and Harvie-Weare (HW) models. The mean activity coefficients of sodium chloride and strontium chloride, and the solubilities for the ternary system at 288.15 K were presented. A comparison between the calculated and measured solubilities shows that the predicted data agree well with the experimental results.     

Volumetric and Surface Properties of Short Chain Alcohols in Aqueous Solution–Air Systems at 293?K

From measurements of the surface tension, density, viscosity and light scattering of aqueous solutions of methanol, ethanol and propanol at 293?K, their activity in the surface monolayer, surface excess concentration, and apparent and partial molar volume were determined. The surface excess concentration of alcohols at the water?Cair interface was determined from the Gibbs equation by using both the alcohol's activity and their molar fraction in the bulk phase and recalculated by using the Guggenheim?CAdam equation. The values of the surface excess concentration determined from the Gibbs equation were also applied to determine the standard Gibbs energy of alcohol adsorption at the water?Cair interface from Langmuir??s equation and compared to those determined from that of Aronson and Rosen.