Synthesis of a tetraazacyclotetradecadiene and a pentaazacyclotetradecatriene

Useful procedures for preparing a novel tetraazacyclotetradecadiene and a pentaazacyclotetradecatriene are reported. J. Heterocyclic Chem., 14, 1097 (1977)     

Wetting of a drop on a sphere

In this work, the equilibrium morphology of a drop on a sphere is analyzed as a function of the contact angle and drop volume experimentally and with analytical effective interfacial energy calculations. Experimentally, a drop on a sphere geometry is realized in an oil bath by placing a water drop on a sphere coated with a dielectric, of which the radii of curvature are comparable with that of the drop. Electrowetting (EW) is used to change the contact angle of the water drop on the sphere. To validate the applicability of EW and the Lippman-Young equation on nonflat surfaces, we systematically investigate the response of the contact angle to the applied voltage (EW response) for various drop volumes and compared the results with the case of a planar surface. The effective interfacial energy of two competing morphologies, namely, the spherically symmetric "completely engulfing" and "partially engulfing" morphologies are calculated analytically. The analytical calculations are then compared to the experimental results to confirm which morphology is energetically more favored for a given contact angle and drop volume. Our findings indicate that the "partially engulfing" morphology is always the energetically more favorable morphology.     

两嵌段共聚高分子链通过薄膜上纳米孑孔隙输运的研究

针对两嵌段高分子链的跨膜输运过程,分别给出与不同输运次序相对戍的高分子链的自由能,进而通过求解Fokker-Planck方程并在不同条件下对平均首次通过时间进行了数值计算.计算结果表明,当共聚高分子链由良溶剂区向不良溶剂区输运时,不能发生线团一链滴转变的链首先输运总是有利于整个高分子链的输运.而在给定输运次序的情况下,化学势、线团一链滴转变、共聚链的组成以及输运速率等因素对输运时间可产生显著影响.相关研究结果可为调控实际生物高分子链的输运时间提供可能的理论线索.     

Force of a gas bubble on a foreign particle in front of a freezing interface

We monitored the formation and development of a single gas bubble on the surface of a spherical particle of size 1.676 mm under unidirectional freezing and thawing (4.6-5.0 microm/s) and for the first time quantitatively estimated the force exerted on this particle by measuring the deformation of an attached elastic stick. The bubble would nucleate and grow on the particle surface closest to the ice front, while the force curve for a freezing-thawing cycle presented a hysteresis characteristic. This force was much greater than in the case without a bubble, and hence it dominated the engulfment process in the present freezing tests. The bubble force increased with increasing bubble size and was shown to be mainly attributable to the elastic force by the deformed bubble shape. Comments were made on the need to incorporate the role of bubbles in predicting the critical velocity to freeze a suspension with high dissolved gas content.     

Rearrangement of a pyranone to a benzothiazole

The conversion of 2-chloromethyl-5-methoxy-4H-pyran-4-one to 2-amino-5-hydroxy-6-methoxybenzothiazole hydrochloride under mild reaction conditions has been observed. The synthesis of the identical benzothiazole by an alternate unequivocal method is also reported.     

Use of a Photovoltaic Receptor in a Phototitrator

Abstract

In phototitrators especially designed to allow operation in ambient light, a photovoltaic device, the Texas Instrument LS 222, may be used instead of the photoresistive diode Texas Instrument 1N2175. This permits elimination of one battery, and a simplier circuit. Construction and performance of the titrator are otherwise identical.     

Thermal properties of a disc-like compound benzene-hexa-n-pentanoate: a precursor of a discotic mesogen

The heat capacity of a disk-like compound, benzene-hexa-n-pentanoate (BH5), a precursor of a discotic mesogen, has been measured by adiabatic calorimetry between 13 and 390 K. BH5 showed four different crystalline phases, but no liquid crystalline phase. Molar entropy and transition entropies were determined and compared with those of other homologues (BH6, BH7, and BH8). An odd-even effect with respect to the number of carbon atoms in the alkyl chain was observed for the cumulative entropies of the phase transitions occurring in the solid state. This effect is discussed by comparing with data for the n-alkanes. The molar entropies of the crystalline state, especially below 250 K, exhibited a peculiar 'pairing effect' between BH(2m- 1) and BH(2m), where m is an integer.     

Thermal properties of a disc-like compound benzene-hexa-n-pentanoate: a precursor of a discotic mesogen

The heat capacity of a disk-like compound, benzene-hexa-n-pentanoate (BH5), a precursor of a discotic mesogen, has been measured by adiabatic calorimetry between 13 and 390 K. BH5 showed four different crystalline phases, but no liquid crystalline phase. Molar entropy and transition entropies were determined and compared with those of other homologues (BH6, BH7, and BH8). An odd-even effect with respect to the number of carbon atoms in the alkyl chain was observed for the cumulative entropies of the phase transitions occurring in the solid state. This effect is discussed by comparing with data for the n-alkanes. The molar entropies of the crystalline state, especially below 250 K, exhibited a peculiar 'pairing effect' between BH(2m- 1) and BH(2m), where m is an integer.     

Local pressure tensor of a simple fluid in a conelike cage of a solid

Asymptotic formulas are derived for distribution functions and components of the pressure tensor for a Van der Waals fluid in a conelike cage of a solid. The formulas describe the local behavior of the fluid far from the vertex of the cone and at rather large distances from solid walls. It is shown that, due to the symmetry of the system, three diagonal components and one off-diagonal component of the pressure tensor differ from zero. The effect of the deviation of conelike pore walls from a cylindrical shape on the appearance of a noticeable contribution to the local characteristics of the fluid in the pore is estimated.     

Observation of a fluorescent dimer of a sulfonated phthalocyanine

With very few exceptions, phthalocyanine dimers are found to be nonfluorescent. We report here the observation of a fluorescent dimer of a tetrasulfonated copper phthalocyanine in ethanol and water. Fluorescence excitation and emission spectra at room temperature and at 77 K are presented. These are consistent with the conventional model of exciton coupling in a cofacial dimer.     

Formation of a tris-capsule and a tris-carceplex from a cyclic six-bowl assembly

A macrocycle composed of six cavitands was assembled into a tris-capsule and a tris-carceplex, each of which encapsulates three guest molecules.     

Partial incorporation of a cyclopentadienyl ligand into a molybdaborane to form a molybdacarbaborane

Reaction of the molybdaborane arachno-2-[Mo(η-C₅H₅)(η⁵:η¹-C₅H₄)B₄H₇] (I) with NEt₃ in toluene at 120 °C for 7 days gives a 90% yield of the molybdacarbaborane nido-1-[Mo(η-C₅H₅)(η³:η²-C₃H₃)C₂B₃H₅] (II). Two of the carbon atoms in the substituted cyclopentadienyl ring in I are incorporated into the metallacarbaborane cluster II. The carbaborane {C₂B₃H₅} fragment in II is attached to an allylic {C₃H₃} group and can be thought of as a new non-planar {C₅B₃H₈} ligand providing seven electrons to the molybdenum atom. Reaction of I with KH in thf at 20 °C gives the anion via deprotonation of a B-H-B bridging proton.     

Impedance of a passive iron electrode in a solution containing a reducing agent

Frequency dependences of impedance of a passive iron electrode in 0.5 M Na₂SO₄ solutions with and without 0.01 M K₄[Fe(CN)₆] are obtained by a pulsed method and the Fourier transform. At 1–1000 Hz, the results in 0.5 M Na₂SO₄ satisfactorily agree with our previous results obtained by a lock-in method. With the [Fe(CN)₆]^4- ions present, the impedance decreases faster at lower frequencies. The impedance of the oxide film/solution interface relaxes longer the film impedance. These conclusions are similar to those obtained earlier.Translated from Elektrokhimiya, Vol. 41, No. 1, 2005, pp. 97–101.Original Russian Text Copyright © 2005 by Klyuev, Rotenberg, Batrakov.To the Centennial of B.N. Kabanov.