Thermogenesis: Identification by means of modulating functions

This paper describes how to obtain an analytic approximation to the transfer function of a conduction calorimeter, namely a procedure to identify the calorimetric system. In this case modulating functions are used directly on the thermogram. The method is used twice: to obtain the time constants and the amplitudes. Its feasibility is tested on two models which span the frequency range usually attained by actual calorimeters. The influence of random noise and baseline drift have also been analyzed. The results show that three or four time constants are correctly obtained.     

Mononuclear and dinuclear copper(I) complexes with a particularly bulky phosphine ligand. Unusual synthesis and crystal structure characterizations

Summary The addition of NPm (diphenylaminodiphenylphosphinomethane) to CuI or the addition of KI to (NPm)₂CuNO₃ leads to the same P-bonded Cu^I complex, (NPm)₂CuI, presenting a trigonal geometry around the Cu atom. The reaction of this new complex (or of its chloro analogue) with a Cu^II salt yields dinuclear species of general formula [(NPm)Cu(-X)₂Cu(NPm)] (X = Cl or I). X-ray analysis of these complexes show that they are isostructural and retain the trigonal geometry around the metal atom. The Cu···Cu distances are 2.775(1)Å for X = Cl and 2.642(1) Å for X = I. The Cu-(-X)-Cu angle is more acute for the iodide [61.48(3)°] than for the chloride [74.17(8)°] complex. These values are discussed in terms of Cu···Cu interactions induced by the electron donor ability of X and the bulk of the phosphine L.     

Stochastic phenomena in a fiber Raman amplifier

The interplay of such cornerstones of modern nonlinear fiber optics as a nonlinearity, stochasticity and polarization leads to variety of the noise induced instabilities including polarization attraction and escape phenomena harnessing of which is a key to unlocking the fiber optic systems specifications required in high resolution spectroscopy, metrology, biomedicine and telecommunications. Here, by using direct stochastic modeling, the mapping of interplay of the Raman scattering‐based nonlinearity, the random birefringence of a fiber, and the pump‐to‐signal intensity noise transfer has been done in terms of the fiber Raman amplifier parameters, namely polarization mode dispersion, the relative intensity noise of the pump laser, fiber length, and the signal power. The obtained results reveal conditions for emergence of the random birefringence‐induced resonance‐like enhancement of the gain fluctuations (stochastic anti‐resonance) accompanied by pulse broadening and rare events in the form of low power output signals having probability heavily deviated from the Gaussian distribution.

     

Synthesis of 8-dipropylamino-7,8,9,10-tetrahydrophenanthridines as potential serotoninergic agonists

A number of 8-dipropylamino-7,8,9,10-tetrahydrophenanthridines have been prepared as analogs of the known serotoninergic agonist 8-hydroxy-2-(dipropylamino)tetralin (8-OH-DPAT) and their affinity for the 5-HT_1A receptor subtype evaluated by radioligand binding assay.     

Highly efficient on-DNA amide couplings promoted by micelle forming surfactants for the synthesis of DNA encoded libraries

DNA encoded libraries (DELs) represent powerful new technology for finding small molecule ligands for proteins and are increasingly being applied to hit finding in medicinal chemistry. Crucial to the synthesis of high quality DELs is the identification of chemical reactions for their assembly that proceed with very high conversion across a range of different substrates, under conditions compatible with DNA-tagged substrates. Many current chemistries used in DEL synthesis do not meet this requirement, resulting in libraries of low fidelity. Amide couplings are the most commonly used reaction in synthesis of screening libraries and also in DELs. The ability to carry out highly efficient, widely applicable amide couplings in DEL synthesis would therefore be highly desirable. We report a method for amide coupling using micelle forming surfactants, promoted by a modified linker, that is broadly applicable across a wide range of substrates. Most significantly, this works exceptionally well for coupling of DNA-conjugated carboxylic acids (N-to-C) with amines in solution, a procedure that is currently very inefficient. The optimisation of separate procedures for coupling of DNA-conjugated acids and amines by reagent screening and statistically driven optimisation is described. The generality of the method is illustrated by the application to a wide range of examples with unprecedented levels of conversion. The utility of the (N-to-C) coupling of DNA-conjugated acids in DEL synthesis is illustrated by the three cycle synthesis of a fully DNA-encoded compound by two cycles of coupling of an aminoester, with intermediate ester hydrolysis, followed by capping with an amine. This methodology will be of great utility in the synthesis of high fidelity DELs.

Highly efficient forward and reverse on-DNA amide couplings were developed exploiting hydrophobic linkers in combination with the micelle forming surfactant TPGS-750M. The method is highly effective for a wide range of substrates in the synthesis of DNA-encoded libraries.     

NMR (195Pt and 13C) contribution to the study of some Pt(II), Pt(IV) and mixed-valence thioamido complexes

The ¹⁹⁵Pt and ¹³C chemical shifts (δ_Pt and δ_c) are reported for platinum(II), platinum(IV) and class II mixed-valence complexes, with general formula [PtL₄]X₂, cis- and trans-PtL₂X₂, PtL₂X₄ and Pt₂L₄X₆ (where L may be thiourea, 2-imidazolidine-thione, tetrahydro 2-pyrimidinethione, thiocaprolactam, pyridine-2-thione and tetramethylthiourea, and X may be Cl or Br). The ¹⁹⁵Pt chemical shifts can be understood in view of ¹³C data in terms of variations of electronegativities and σ-donor abilities of ligands attached to platinum.     

A possible route to oxamic-platinum-blue: Nature and reactivity of a stable intermediate

Summary Oxamic acid is a ligand which offers several potential coordination sites, From its reaction in an aqueous medium with K₂[Pt(NO₂)₄] it is possible to isolate a complex (A) which constitutes a first step in the formation of oxamic-platinum-blue (C), together with green species whose structures are much more difficult to define. Elemental analyses and i.r. spectra of such a series allow one to postulate a formation mechanism for the oxamic platinum-blues.     

Platinum(II) complexes with ligands involving the -NH-CS-NH-Group in heterocyclic rings

Summary The reaction of PtCl₂ or K₂PtCl₄ with thiocaprolactam (1), tetrahydro-2-pyrimidinethione (2), 2-imidazolidinethione (ethylenethiourea) (3), and 2-thioxoimidazolinone (thiohydantoin (4) yields complexes of general formula [PtL₄]Cl₂, PtLCl₂, or PtL₂Cl₂. These complexes have been characterized by elemental analysis, i.r. and n.m.r. spectroscopy. The coordination site is discussed in the light of the various data obtained.     

Interstack Interactions in Potassium Bis(1,2-Cyclobutenedione 3,4-dithiolato) Palladate. Crystal Structure

Abstract

Potassium bis(1,2-cyclobutenedione 3,4-dithiolato) palladate (Pd(dithiosquarato)₂K₂) crystallizes in the monolinic system, space group P2₁/c, a = 8.046(2), b = 15.235(4), c = 6.289(1). The dithiosquarate entities are stacked in parallel columns separated by potassium cations and water molecules. π-interactions within a stack are evidenced by the short stacking distance (3.51 Å). Further interstack interactions involve close S…O or O…O interstack contacts. (～3.5 Å). As a result, the structural arrangement is nearly two-dimensional. Conductivity measurements carried out on pressed pellets show a semi-conductive behavior (σ = 2 × 10^?5 Ω^?1 cm¹).