A “sodium trap” based on benzo-15-crown-5 with an exocyclic N-(thiophosphoryl)thiourea moiety

For N-(thio)phosphorylthioureas of the common formula RC(S)NHP(X)(OiPr)₂HL^I (R = N-(4′-aminobenzo-15-crown-5), X = S), HL^II (R = N-(4′-aminobenzo-15-crown-5), X = O), HL^III (R = PhNH, X = S), HL^IV (R = PhNH, X = O), and (N,N′-bis-[C(S)NHP(S)(OiPr)₂]₂-1,10-diaza-18-crown-6) H₂L^V, salts LiL^I,III,IV, NaL^I–IV, KL^I–IVM₂L^V (M = Li⁺, Na⁺, K⁺), Ba(L^I,III,IV)₂, and BaL^V have been synthesized and investigated. Compounds NaL^I,II quantitatively drop out as a deposit in ethanol medium, allowing the separation of Na⁺ and K⁺ cations. This effect is not displayed for the other compounds. The crystal structures of HL^III and the solvate of the composition [K(Me₂CO)L^III] have been investigated by X-ray crystallography.     

Tris(Trimethylsilyl)Phosphine in Reaction with Bis(Phenylenedioxa)Chlorophosphorane. The Way to Phosphoranylphosphines

Abstract

Tris(trimethy1silyl)phosphine (1) is the key reagent in the synthesis of one- and two-coordinated phosphorus compounds. Its characteristic features are extreme reactivity, high nucleophility of phosphorus atom and the P-Si bonds lability. The interaction of phosphine (1) with bis(catecho1)chlorophosphome (2) has been studied by dynamic ³¹P NMR method. On the reagents ratio 1:1 at first the nucleophilic substitution of chlorine occurs leading to formation of phosphome (3) with P^III-P^v bond (σ_P(III) -117.0, σ^P(V) 17.4 ppm, ¹J_pp 305.0 Hz) which converts then into more stable 2-(trimethylsiloxyphenyloxy)-4,5-bem- 1,3,2-dioxaphospholane (4).     

Foreword

Nonlinear Dynamics -     

Platinum(II) diimine complexes with catecholate ligands bearing imide electron-acceptor groups: synthesis, crystal structures, (spectro)electrochemical and EPR studies, and electronic structure

A series of catechols with attached imide functionality (imide = phthalimide PHT, 1,8-naphthalimide NAP, 1,4,5,8-naphthalenediimide NDI, and NAP-NDI) has been synthesized and coordinated to the Pt (II)(bpy*) moiety, yielding Pt(bpy*)(cat-imide) complexes (bpy* = 4,4'-di- tert-butyl-2,2'-bipyridine). X-ray crystal structures of PHT and NAP complexes show a distorted square-planar arrangement of ligands around the Pt center. Both complexes form "head-to-tail" dimers in the solid state through remarkably short unsupported Pt...Pt contacts of 3.208 (PHT) and 3.378 A (NAP). The Pt(bpy*)(cat-imide) complexes are shown to combine optical (absorption) and electrochemical properties of the catecholate (electron-donor) and imide (electron-acceptor) groups. The complexes show a series of reversible reduction processes in the range from -0.5 to -1.9 V vs Fc (+)/Fc, which are centered on either bpy* or imide groups, and a reversible oxidation process at +0.07 to +0.14 V, which is centered on the catecholate moiety. A combination of UV-vis absorption spectroscopy, cyclic voltammetry, UV-vis spectroelectrochemistry, and EPR spectroscopy has allowed assignment of the nature of frontier orbitals in Pt(bpy*)(cat-imide) complexes. The HOMO in Pt(bpy*)(cat-imide) is centered on the catechol ligand, while the LUMO is localized either on bpy* or on the imide group, depending on the nature of the imide group involved. Despite the variations in the nature of the LUMO, the lowest-detectable electronic transition in all Pt(bpy*)(cat-imide) complexes has predominantly ligand-to-ligand (catechol-to-diimine) charge-transfer nature (LLCT) and involves a bpy*-based unoccupied molecular orbital in all cases. The LLCT transition in all Pt(bpy*)(cat-imide) complexes appears at 530 nm in CH2Cl2 and is strongly negatively solvatochromic. The energy of this transition is remarkably insensitive to the imide group present, indicating lack of electronic communication between the imide and the catechol moieties within the cat-imide ligand. The high extinction coefficient, approximately 6 x 10(3) L mol(-1) cm(-1) of this predominantly LLCT transition is the result of the Pt orbital contribution, as revealed by EPR spectroscopy of the complexes in various redox states. The CV profile of the oxidation process of Pt(bpy*)(cat-imide) in CH2Cl2 and DMF is concentration dependent, as was shown for NDI and PHT complexes as typical examples. Oxidation appears as a simple diffusion-limited process at low concentrations, with an increasing anodic-to-cathodic peak separation eventually resolving as two independent consecutive waves as the concentration of the complex increases. It is suggested that aggregation of the complexes in the diffusion layer in the course of oxidation is responsible for the observed concentration dependence. Overall, the Pt(bpy*)(cat-imide) complexes are electrochromic compounds in which a series of stepwise reversible redox processes in the potential range from 0.2 to -2 V (vs Fc (+)/Fc) leads to tuneable absorbencies between 300 and 850 nm.     

Oscillator Representation for Pseudoharmonic Potential

Oscillator representation method is applied to obtain the bound state energy eigenvalues and the corresponding eigenfunctions of the n-dimensional Schrödinger equation for the pseudoharmonic potential with arbitrary angular momentum.     

Fast head-related transfer function measurement via reciprocity

An efficient method for head-related transfer function (HRTF) measurement is presented. By applying the acoustical principle of reciprocity, one can swap the speaker and the microphone positions in the traditional (direct) HRTF measurement setup, that is, insert a microspeaker into the subject's ear and position several microphones around the subject, enabling simultaneous HRTF acquisition at all microphone positions. The setup used for reciprocal HRTF measurement is described, and the obtained HRTFs are compared with the analytical solution for a sound-hard sphere and with KEMAR manikin HRTF obtained by the direct method. The reciprocally measured sphere HRTF agrees well with the analytical solution. The reciprocally measured and the directly measured KEMAR HRTFs are not exactly identical but agree well in spectrum shape and feature positions. To evaluate if the observed differences are significant, an auditory localization model based on work by J. C. Middlebrooks [J. Acoust. Soc. Am. 92, 2607-2624 (1992)] was used to predict where a virtual sound source synthesized with the reciprocally measured HRTF would be localized if the directly measured HRTF were used for the localization. It was found that the predicted localization direction generally lies close to the measurement direction, indicating that the HRTFs obtained via the two methods are in good agreement.     

Higher-order modulation instability in nonlinear fiber optics

We report theoretical, numerical, and experimental studies of higher-order modulation instability in the focusing nonlinear Schr?dinger equation. This higher-order instability arises from the nonlinear superposition of elementary instabilities, associated with initial single breather evolution followed by a regime of complex, yet deterministic, pulse splitting. We analytically describe the process using the Darboux transformation and compare with experiments in optical fiber. We show how a suitably low frequency modulation on a continuous wave field induces higher-order modulation instability splitting with the pulse characteristics at different phases of evolution related by a simple scaling relationship. We anticipate that similar processes are likely to be observed in many other systems including plasmas, Bose-Einstein condensates, and deep water waves.     

Self-adjoint sub-classes of generalized thin film equations

In this work we consider a class of fourth-order nonlinear partial differential equation containing several un-specified coefficient functions of the dependent variable which encapsulates various mathematical models used, e.g. for describing the dynamics of thin liquid films. We determine the subclasses of these equations which are self-adjoint. By using a general theorem on conservation laws proved by one of the authors (NHI) we find conservation laws for some of these partial differential equations without classical Lagrangians.