On Homomorphisms Indexed by Semistandard Tableaux

We describe techniques which may be used to compute the homomorphism space between Specht modules for the Hecke algebras of type A. We prove a q-analogue of a result of Fayers and Martin and show how it may be applied to construct homomorphisms between Specht modules. In particular, we show that in certain cases the dimension of the homomorphism space is given by the corank of a matrix whose entries we write down explicitly.     

Daisy chain assembly formed from a cucurbit[6]uril derivative

The building block synthesis of a derivative of CB[6] that bears a reactive propargyloxy group and its functionalization by click chemistry to yield 1 which contains a covalently attached isobutylammonium group is presented. Compound 1 undergoes self-assembly to yield a cyclic [c2] daisy chain assembly (1(2)) in water. The behavior of 1(2) in response to various stimuli (e.g., guests and CB[n] receptors) is described.     

A Nexus between Theory and Experiment: Non‐Empirical Quantum Mechanical Computational Methodology Applied to Cucurbit[n]uril⋅Guest Binding Interactions

A training set of eleven X‐ray structures determined for biomimetic complexes between cucurbit[n]uril (CB[7 or 8]) hosts and adamantane‐/diamantane ammonium/aminium guests were studied with DFT‐D3 quantum mechanical computational methods to afford ΔG_calcd binding energies. A novel feature of this work is that the fidelity of the BLYP‐D3/def2‐TZVPP choice of DFT functional was proven by comparison with more accurate methods. For the first time, the CB[n] ? guest complex binding energy subcomponents [for example, ΔE_dispersion, ΔE_{electrostatic}, ΔG_solvation, binding entropy (?TΔS), and induced fit E_{deformation(host)}, E_{deformation(guest)}] were calculated. Only a few weeks of computation time per complex were required by using this protocol. The deformation (stiffness) and solvation properties (with emphasis on cavity desolvation) of cucurbit[n]uril (n=5, 6, 7, 8) isolated host molecules were also explored by means of the DFT‐D3 method. A high ρ²=0.84 correlation coefficient between ΔG_exptl and ΔG_calcd was achieved without any scaling of the calculated terms (at 298 K). This linear dependence was utilized for ΔG_calcd predictions of new complexes. The nature of binding, including the role of high energy water molecules, was also studied. The utility of introduction of tethered [‐(CH₂)_nNH₃]⁺ amino loops attached to N,N‐dimethyl‐adamantane‐1‐amine and N,N,N′,N′‐tetramethyl diamantane‐4,9‐diamine skeletons (both from an experimental and a theoretical perspective) is presented here as a promising tool for the achievement of new ultra‐high binding guests to CB[7] hosts. Predictions of not yet measured equilibrium constants are presented herein.     

Die Synthese aliphatischer Organophosphorverbindungen mit Hilfe von Diäthylaminodichlorphosphin

Zusammenfassung Diäthylaminodichlorohosphin, (C₂H₅)₂NPCl₂, hergestellt aus PCl₃ und Diäthylamin, reagierte mit C₈H₁₇MgBr zu Dioctylphosphinigsäure, (C₈H₁₇)₂P(O)H, die mit H₂O₂ zur Phosphinsäure oxydiert wurde. Polyoctamethylenphosphinsäure wurde in 67% Ausbeute als eine in organischen Lösungsmitteln unlösliche weiße Substanz in ähnlicher Weise, unter Verwendung von BrMg(CH₂)₈MgBr, erhalten. *** DIRECT SUPPORT *** A3615144 00016

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Synthesis of Aliphatic Organophosphorus compounds

Diethylaminodichlorophosphine, prepared from PCl₃ and diethylamine, reacted with C₈H₁₇MgBr to give dioctylphosphinous acid, (C₈H₁₇)₂P(O)H. Oxidation of this compound with H₂O₂ produced dioctylphosphinic acid, (C₈H₁₇)₂P(O)OH. In an analogous reaction sequence employing BrMg(CH₂)₈MgBr polyoctamethylenephosphinic acid was obtained in 67% yield. This polymer is insoluble in organic solvents.

     

Mass spectra of a series of 2-p-substituted phenyl-1,3,2-dioxaborolanes

The mass spectra of a series of 2-p-substituted phenyl-1,3,2-dioxaborolanes have been examined and compared with the mass spectrum of 2-phenyl-1,3,2-dioxaborolane. Formation of the substituted ion [C₇H₆X]⁺ by electron impact induced rearrangement has been found to be influenced significantly by the presence and nature of the substituent at the para position of the phenyl ring.     

Co-precipitation of metal dimethylglyoximates generated from biacetyl monoxime or biacetyl and hydroxylamine

A study has been made of some aspects of the co-precipitation of gold and platinum(II) and (IV) with palladium(II) precipitated from homogeneous solution initially containing biacetyl and hydroxylamine in 0.3M hydrochloric acid. The co-precipitation of nickel(II) with palladium(II) and vice versa from near neutral solutions initially containing biacetyl and hydroxylamine was also explored; the solid is enriched in the minor constituent in both cases. As with biacetyl monoxime-hydroxylamine systems, both nickel(II) and palladium(II) promote formation of dimethylglyoxime from such solutions between pH 7 and 8. Factors leading to this unusual behaviour in co-precipitation are discussed and a qualitative explanation tentatively advanced. The co-precipitation of nickel and palladium(II) is different when biacetyl monoxime solutions are used; the former comes out of solution faster than the latter irrespective of their concentration ratio. This disparity in the reaction rates can be used to separate nickel directly from palladium(II) by precipitation or extraction of the dimethylglyoximate into chloroform.     

A cucurbit[6]uril analogue: host properties monitored by fluorescence spectroscopy

This paper describes the host properties of a new cucurbit[6]uril analogue, studied by fluorescence and 1H NMR spectroscopy. This host has an elongated cavity with oval-shaped portals. It is intrinsically fluorescent, and more importantly, this fluorescence is sensitive to guest encapsulation, allowing for the study of the inclusion of nonfluorescent guests by fluorescence spectroscopy. In the case of benzene as guest, significant enhancement of the cucurbit[6]uril analogue host fluorescence was observed upon addition of benzene; this allowed for the determination of the binding constant for 1:1 host-guest complexation, yielding a value of K = 6900 +/- 1100 M(-1). This complexation was also studied by 1H NMR, yielding a similar value of K = 8980 +/- 500 M(-1). The binding of a much larger guest, the dye Nile Red, was also studied, but in this case using guest fluorescence. Significant suppression of the Nile Red fluorescence was observed upon 1:1 complexation with the cucurbit[6]uril analogue, with an extremely large binding constant of 8.2 +/- 0.5 x 10(6) M(-1), indicating a very strong host-guest interaction and an excellent size and shape match. In both cases, binding was much stronger than in the case of the same guests with cucurbit[6]uril itself, and in the case of Nile Red, binding was also much stronger than with modified beta- or gamma-cyclodextrins. This is partly a result of the partial aromatic nature of the host walls, which allow for pi-pi interactions not possible in cucurbiturils or cyclodextrins. The ability to study its inclusion complexes using either host or guest fluorescence, and the very high binding constants observed, illustrates the versatility and potential usefulness of this new host compound.     

A spectrophotometric determination of europium in lanthanide and other mixtures by use of Methylene Blue

A spectrophotometric determination of 0.1-1 mg of europium in a lanthanide(III) mixture is described. Europium(III) is selectively reduced in a Jones reductor and the europium(II) allowed to react with a measured excess of Methylene Blue (MB) solution. The dye is reduced to the colourless leuco form according to the equation, MB + 2 Eu(II)-->leuco MB + 2 Eu(III) and the excess of MB is determined spectrophotometrically at 664 nm. Optimum conditions are discussed and various applications presented.     

Extraction and spectrophotometric determination of cobalt with dithizone

Cobalt(II) in acetate-tartrate buffer (pH 6.0-7.3) is extracted quantitatively as cobalt(III) dithizonate with excess of dithizone in CCl(4). The molar absorptivity in the CCl(4) phase is 4.6 x 10(4) 1.mole(-1).cm(-1) at the absorption maximum 550 nm. The calibration graph is linear for 1-10 mug of cobalt in 10 ml of CCl(4) when excess of dithizone is removed by back-extraction with 0.01M aqueous ammonia. Most interferences can be overcome by (a) initial extraction with dithizone at pH 1.3, (b) selective back-extraction into hydrochloric acid (pH 1 to 2), (c) oxidation of iron and tin to iron(III) and tin(IV) and addition of fluoride to complex the former, and (d) selective reaction of nickel dithizonate with 1,10-phenanthroline in the CCl(4) phase followed by back-extraction of nickel into 0.1M acid. The method has been applied to determination of cobalt in a copper-nickel-zinc alloy and a nimonic alloy.