Effective refractive index and intermolecular forces associated with a phase of functional groups

Cases in which a functional groups form distinct phases are known in material science in general and specifically in polymer and surfactant sciences. To calculate the van der Waals forces associated with such phases there is a need to evaluate the refractive index of those phases. We expand and generalize a method to estimate the refractive index of such ‘functional group phase’ and discuss how to use the refractive indices to calculate the interaction energies associated with such functional group phases and thereby modify the total theoretically calculated van der Waals forces.     

A mononuclear cobalt(II) hydroxo complex: synthesis,molecular structure,and reactivity studies

A novel Co(II) hydroxo complex Co{HB(3-^tBu-5-ⁱPrpz)₃}(OH) 4 {where HB(3-^tBu-5-ⁱPrpz)₃ = hydrotris(3-tert-butyl-5-isopropylpyrazol-l-yl)borate} has been prepared and its molecular structure has been determined by X-ray crystallography. This complex is mononuclear with distorted tetrahedral geometry. The reaction of CO₂ with Co{HB(3-^tBu-5-ⁱPrpz)₃}(OH) resulted in the formation of a μ-carbonato bridged binuclear complex [Co{HB(3-^tBu-5-ⁱPrpz)₃}]₂(CO₃) wherein the carbonate group is bound to both metal centers in an asymmetrical manner. In order to explore the role of labile metal complexes in promoting ester hydrolysis, complexes [Co{HB(3,5-ⁱPr₂pz)₃}]₂(OH)₂ and Co{HB(3-^tBu-5-ⁱPrpz)₃}(OH) have been used as catalysts in the hydrolysis of both carboxylate as well as phosphate esters. The product of 4-nitrophenylacetate hydrolysis with Co{HB(3-^tBu-5-ⁱPrpz)₃}(OH) was isolated as four coordinate Co{HB(3-^tBu-5-ⁱPrpz)₃}(OC₆H₄-4-NO₂) 6, whereas the reaction of 4-nitrophenyltrifluoroacetate with [Co{HB(3,5-ⁱPr₂pz)₃}]₂(OH)₂ resulted the formation of the six coordinate Co{HB(3,5-ⁱPr₂pz)₃}(OC₆H₄-4-NO₂)(MeCN)₂ species. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.

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Drop retention force as a function of resting time

The force, f, required to slide a drop on a surface is shown to be a growing function of the time, t, that the drop waited resting on the surface prior to the commencement of sliding. In this first report on the resting time effect, we demonstrate the existence of this phenomenon in different systems, which suggests that this phenomenon is general. We show that d f/d t is never negative. The shorter the resting times, the higher d f/d t is. As the resting time increases, d f/d t decreases toward zero (plateau) as t --> infinity. The increase in the force, Delta f, due to the resting time effect (i.e., f( t --> infinity) - f( t --> 0)) correlates well with the vertical component of the liquid-vapor surface tension, and we attribute this phenomenon to the corrugation of the surface by the drop due to this unsatisfied normal component of Young's equation.     

Drop retention force as a function of drop size

The force, f, required to slide a drop past a surface is often considered in the literature as linear with the drop width, w, so that f/w = const. Furthermore, according to the Dussan equation for the case that the advancing and receding contact angles are constant with drop size, one can further simplify the above proportionality to f/V(1/3) = const where V is the drop volume. We show, however, that experimentally f/V(1/3) is usually a decaying function of V (rather than constant). The retention force increases with the time the drop rested on the surface prior to sliding. We show that this rested-time effect is similar for different drop sizes, and thus the change of f/V(1/3) with V occurs irrespective of the rested-time effect which suggests that the two effects are induced by different physical phenomena. The time effect is induced by the unsatisfied normal component of the Young equation which slowly deforms the surface with time, while the size effect is induced by time independent properties. According to the Dussan equation, the change of f/V(1/3) with V is also expressed in contact angle variation. Our results, however, show that contact angle variation that is within the scatter suffices to explain the significant force variation. Thus, it is easier to predict contact angle variation based on force variation rather than predicting force variation based on contact angle variation. A decrease of f/V(1/3) with V appears more common in the system studied compared to an increase.     

Structural elucidation of propargylated products of 3-substituted-1,2,4-triazole-5-thiols by NMR techniques

Propargylation of 3-substituted-1,2,4-triazole-5-thiols, which predominantly exist as their thione tautomers, was carried out with the view to synthesize different heterocycles and study their biological activity. Three different products namely, a mono S-propargyl and two S,N-dipropargyl regioisomers, arising from N1/N2 substitution, were isolated and characterized. Unambiguous structural elucidation of the regioisomers of S,N-dipropargyl derivatives was achieved by means of (13)C-(1)H HMBC technique. The proportion of the regioisomers was found to vary with the substituent on the 1,2,4-triazole thiols. No product corresponding to N4 substitution was isolated from any of the reactions carried out.     

Determination of aliphatic amines by high-performance liquid chromatography-amperometric detection after derivatization with naphthalene-2,3-dicarboxaldehyde

A simple and sensitive liquid chromatographic method has been developed for the determination of low molecular weight aliphatic amines after their pre-column derivatization with naphthalene-2,3-dicarboxaldehyde (NDA). Derivatization conditions, including the NDA concentration, reaction pH and reaction time have been investigated for method optimization. The chromatographic separation of five amines was performed on ABZ PLUS column using mobile phase of methanol-water (80:20, v/v) at a flow rate of 0.2 mL min⁻¹. The detection was carried out with a 6 mm glassy carbon electrode at the applied potential of 0.7 V versus Ag/AgCl reference electrode. The detection limits were between 23.3 and 34.4 nmol L⁻¹ of amines with a sample injection volume of 2 μL. The present method was applied for the determination of aliphatic amines in lake water. The recovery ranged 52.2-127.9%. The RSD in analytes retention time was less than 0.3% and 2.4% for intra- and inter-day analyses, respectively. The RSD in peak area was below 5.8% for both intra-day and inter-day analyses. The total analysis was completed within 20 min.     

As-placed contact angles for sessile drops

As-placed contact angle is the contact angle a drop adapts as a result of its placement on a surface. As expected, the as-placed contact angle, thetaAP, of a sessile drop on a horizontal surface decreases with the drop size due to the increase in hydrostatic pressure. We present a theoretical prediction for thetaAP which shows that it is a unique function of the advancing contact angle, thetaA, drop size, and material properties (surface tensions and densities). We test our prediction with published and new data. The theory agrees with the experiments. From the relation of the as-placed contact angle to drop size the thermodynamic equilibrium contact angle is also calculated.     

Polysaccharide-Silica Hybrids: Design and Applications

This article discusses and reviews the current status and future perspectives of silica hybrids of polysaccharides and biosilicas derived thereof. The hybrids have been produced in various morphological shapes and utilized in water remediation, separation, enzyme immobilization, sensor, and biomedical fields. The polysaccharides show templating and structure directing influence in manipulation of sol gel silica hybrid materials which can be calcined to derive functional biosilicas. The development of energy storage devices and white light emitting solid phosphors may be the fields of future research.     

Hybrid Class Phenylthiazole and 1,2,3,4‐Tetrahydronaphthalene Target Sertraline Transporter for Antidepressant Action Revealed by Molecular Docking Studies

Phenylthiazolyl‐substituted 1,2,3,4‐tetrahydronaphthalene derivatives were synthesized, and their chemical structures were elucidated by Fourier transform infrared, ¹H‐NMR, ¹³C‐NMR spectral data and elemental analyses. Antidepressant‐like activities of these compounds were screened using both Porsolt's behavioural despair on albino mice and tail suspension tests. Open field test was also performed for the examination of probable neurological deficits, which may interfere with the test results. The test compounds exhibited different levels of antidepressant activities. Additionally, the key ligand was further substantiated by docking experiment to explore plausible mode of binding in molecular dynamics overflow. The studies elucidates role of a hydrophilic H‐bonding region and pi‐cation binding as a major driving force for biological activity.