Kobalt(III) ammin-derivate einiger Reineckesalz-Analoga mit Toluidinen

Zusammenfassung Es wurden 39 neue Komplexsalze durch doppelte Umsetzung aus wäßrig-alkohol. Lösungen der folgenden Reineckeat-Analoga: [Cr(NCS)₄(o-Toluidin)₂]^–, [Cr(NCS)₄(m-Toluidin)₂]^– und [Cr(NCS)₄(p-Toluidin)₂]^– und Hexammin-, Monoacido-pentammin-und Diacido-tetrammin-kobalt(III)-komplexsalze erhalten.Es wurden in einigen Fällen Abweichungen in physikochemischen Eigenschaften, wie Farbtönung, Kristallform, Löslichkeit und papierchromatographischeR _F-Werte, bei den stellungsisomeren Salzen vom Typus: Kation·[Cr(NCS)₄(Toluidin)₂] und auch bei den Koordinationsisomerpaaren: [Co(DH)₂(o-Toluidin)₂][Cr(NCS)₄(p-Toluidin)₂] und [Co(DH)₂(p-Toluidin)₂] [Cr(NCS)₄(o-Toluidin)₂], usw. beobachtet.

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Cobalt(III) ammine derivatives of some reineckate analogues with toluidines

39 new complex salts were prepared by double conversion of the reineckate analogues [Cr(SCN)₄(o-toluidine)₂]^–, [Cr(SCN)₄(m-toluidine)₂]^–, and [Cr(SCN)₄(p-toluidine)₂]^– with the hexammine, monoacido-pentammine and diacido-tetrammine complexes of Co(III). In some of the position and coordination isomers deviations from the standard physico-chemical properties, i.e. color, crystal form, solubility and paper chromatographyR _f-values were observed.

     

Mobile-phone-based classroom response systems: Students’ perceptions of engagement and learning in a large undergraduate course

Using a Classroom Response System (CRS) has been associated with positive educational outcomes, by fostering student engagement and by allowing immediate feedback to both students and instructors. This study examined a low-cost CRS (VotApedia) in a large first-year class, where students responded to questions using their mobile phones. This study explored whether the use of VotApedia retained the advantages of other CRS, overcame some of the challenges of other CRS, and whether new challenges were introduced by using VotApedia. These issues were studied within three themes: students’ perceptions of using VotApedia; the impact of VotApedia on their engagement; and the impact of VotApedia on their learning. Data were collected from an online survey, focus groups and student feedback on teaching and course content. The results indicated that using VotApedia retains the pedagogical advantages of other CRS, while overcoming some of the challenges presented by using other CRS, without introducing any new challenges.     

Neue Reineckesalzanaloge Verbindungen mit tertiären aromatischen Aminen

Substitution reactions of anhydrous K₃[Cr(NCS)₆] with tertiary aromatic monoamines such as N,N-dimethylaniline and N,N-diethylaniline were carried out in the absence of solvents. The tertiary amines readily form compounds analogous to Reinecke salts,amine ₂H[Cr(NCS)₄(N,N-dimethylaniline)₂] andamine ₂H[Cr(NCS)₄(N,N-Diethylaniline)₂] respectively. The formula of the new complex anions was established by a series of double decomposition reactions with the hydrochlorides of some heterocyclic N-bases, alcaloids and cobalt(III)-ammine complexes. Some structural problems were resolved by UV and IR spectroscopic studies.     

Inverse suspension polymerization of acrylamide

The polymerization of acrylamide in inverse suspension is described and compared with polymerization in solution. The influences of various factors upon the molecular weight of the polymer were studied, viz. the concentration of initiator, the procedure of aqueous phase addition, the nature and concentration of emulsifier, the salt concentration, the time between mixing of phases and start of polymerization etc. Conductometry, NMR and electron microscopy were employed in order to establish the reaction stages and the characteristics of the polymers. The results indicate the importance of each factor and lead to an understanding of the polymerization.     

Oxygenation of the cobalt(II) complex of an unsymmetrical bis-Schiff base

Summary The cobalt(II) complex of an unsymmetrical bis-Schiff base. Co(dha, salen), has been prepared. In the presence of pyridine, it forms both monomeric superoxo and dimeric peroxo adducts with dioxygen. At –10°C and lower temperatures, the adduct formed in pyridine solution is mainly superoxo as shown by electronic and e.s.r. spectra as well as volumetric measurement of oxygen uptake. The solid adduct precipitated by addition of toluene is predominantly peroxo as shown by elemental analysis, i.r. spectrum, magnetic and thermogravimetric measurements. Comparison of the oxygen affinities of this complex and of the symmetrical Co(salen) is discussed.     

Conformal blocks in Virasoro and W theories: Duality and the Calogero–Sutherland model

We study the properties of the conformal blocks of the conformal field theories with Virasoro or W-extended symmetry. When the conformal blocks contain only second-order degenerate fields, the conformal blocks obey second order differential equations and they can be interpreted as ground-state wave functions of a trigonometric Calogero–Sutherland Hamiltonian with non-trivial braiding properties. A generalized duality property relates the two types of second order degenerate fields. By studying this duality we found that the excited states of the Calogero–Sutherland Hamiltonian are characterized by two partitions, or in the case of _WAk−1${\mathrm{WA}}_{k-1}$ theories by k   partitions. By extending the conformal field theories under consideration by a u(1)$u(1)$ field, we find that we can put in correspondence the states in the Hilbert state of the extended CFT with the excited non-polynomial eigenstates of the Calogero–Sutherland Hamiltonian. When the action of the Calogero–Sutherland integrals of motion is translated on the Hilbert space, they become identical to the integrals of motion recently discovered by Alba, Fateev, Litvinov and Tarnopolsky in Liouville theory in the context of the AGT conjecture. Upon bosonization, these integrals of motion can be expressed as a sum of two, or in general k, bosonic Calogero–Sutherland Hamiltonian coupled by an interaction term with a triangular structure. For special values of the coupling constant, the conformal blocks can be expressed in terms of Jack polynomials with pairing properties, and they give electron wave functions for special Fractional Quantum Hall states.     

Synthesis of Beaded Polyvinyl Alcohol by Suspension Methanolysis of Polyvinyl Acetate: Derivatization and Some Applications

A new procedure for the synthesis of porous and nonporous polyvinyl alcohol beads by controlled methanolysis of different concentrations of polyvinyl acetate suspension is described. By crosslinking with epichlorohydrin, insoluble crosslinked polyvinyl alcohol gels were obtained. These gels exhibit some peculiar swelling properties related to the reticulation degree, probably due to the interchain hydrogen associations. Crosslinked polyvinyl alcohol beads can be used as supports for liquid chromatography and for enzyme immobilization. Some new stationary phases for affinity chromatography and for ion-exchange chromatography were obtained. No substantial modifications in the catalytic properties of enzyme immobilized on crosslinked polyvinyl alcohol gels were established.