Circularly‐Polarized Electrochemiluminescence from a Chiral Bispyrene Organic Macrocycle

The first observation of circular polarization of electrochemiluminescence (ECL) from a purely organic derivative is reported. A bispyrene scaffold mounted on a constrained polyether macrocycle displaying intense excimer fluorescence and highly circularly‐polarized (CP) photoluminescence has been selected for this purpose. The compound displays an ECL dissymmetry factor of about |8×10^?3|, which is in good agreement with the corresponding photoluminescence value. This observation is the first step towards the molecular engineering of tailored dyes that can act as both ECL and CP‐ECL reporters for (bio)analysis by bringing a new level of information when dealing with chiral environments. Additionally, it provides an extra dimension to the ECL phenomenon and opens the way to chiral detection and discrimination.     

On the numerical computation of Generalized Burmester Points

This note describes a procedure for plane higher-curvature path analysis and synthesis. All coefficients have been written in terms of elementary instantaneous invariants. This facilitates the numerical computation of Generalized Burmester Points for a moving link of a planar mechanism in a non-symmetric position. FORTRAN subroutines have been written and a numerical example is provided.

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Sommario Si descrive una procedura di analisi e sintesi per meccanismi piani generatori di traiettoria con approssimazione del quarto ordine. Nella formulazione adottata, l'impiego degli invarianti istantanei elementari consente di valutare analiticamente i termini delle equazioni per la ricerca dei punti generalizzati di Burmester. Sono state implementate subroutines in linguaggio FORTRAN ed è stato sviluppato un esempio numerico.

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Nomenclature P _o velocity pole - inflection circle diameter - angle of rotation of the moving body - r _f ,r _m radii of curvature of the fixed and moving polodes, respectively - dl infinitesimal arc length measured on the polode - a,b coordinates ofP _o , in the canonical reference system¹ - a _i ,b _i i-th derivatives ofa andb, respectively, computed at the initial position (i.e. =0). These are the elementary instantaneous invariants - h,* polar coordinates of the moving point in the canonical reference system (0 ) - radius of curvature of the point-path trajectory - _E radius of curvature of the evolute of the point-path trajectory - _E ^/(2) radius of curvature of the evolute of the evolute of the point-path trajectory A canonical reference system is a rectangular right-handed cartesian system having they-axis directed toward inflexion pole, origin in the velocity pole.     

A stereoselective route to 6-substituted pyrrolo-1,5-benzoxazepinones and their analogues

We developed a novel and convenient stereoselective path for the preparation of pyrrolo-1,5-benzoxazepinones (PBOs). This innovative route envisaged the employment of (−)-menthol as convenient chiral auxiliary and a key S_NAr for the stereoselective preparation of a tertiary aryl–alkyl ether. As a further advancement, we exploited this newly conceived synthetic route for the preparation of 2-substituted PBO analogues to either undergo biological evaluation themselves or give access to a variety of further functionalization options.     

L'Opera geometrica di Evangelista Torricelli

Mit 23 Figuren im Text.     

Ethene hydroformylation with CO/H2O: nucleophilic attack by water on to a terminal CO of a Ru(II) acylcarbonyl complex

The reaction with water of acyldicarbonyl-Ru(II) complexes relevant to ruthenium catalysed ethene hydrocarbonylation with CO/H2O is shown to consist of a nucleophilic attack and to proceed via coordination of propionate and CO to the Ru(II) species.     

Esistenza ed unicita’ delle soluzioni di un problema misto per un sistema iperbolico simmetrico con coefficienti discontinui

In this paper we give existence and uniqueness theorems for weak solutions of a mixed initial and boundary value problem with conservative boundary conditions relating to a particular symmetric hyperbolic linear system with discontinuous coefficients. The unicity is proved also for a mixed non linear problem.     

Identification of RFLP G6PD mutations by using microcapillary electrophoretic chips (Experion)

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is one of the most well-known human genetic defects, identified in more than 400 million individuals in the world. To date, no commercial kits are available for the mutation screening of this disease. Seventy G6PD-deficient Italian individuals admitted to the Laboratory of Clinical Molecular Biology of Hospital "Agostino Gemelli" of Rome were screened for the most frequent Italian mutations, by means of allele-specific PCR, followed by restriction fragment length electrophoresis. The present study compares two techniques for the identification of restriction patterns: agarose gel electrophoresis versus Experion system. When the first screening was negative, the entire G6PD gene was sequenced using the ABI 3100 Avant Instrumentation. The G6PD variants identified and their frequencies were the following: G6PD Mediterranean (75.7%), G6PD Seattle (7.1%), G6PD A(-) 202 + 376 (7.1%), and G6PD Cassano (2.8%). In addition, we identified by direct sequencing two new mutations, namely Buenos Aires and Rignano. With the Experion method, the size band determination was more accurate than that obtained by gel electrophoresis. The Experion system resulted as a valid, easy, and reproducible diagnostic method for the screening of G6PD mutation as compared with the agarose electrophoretic analysis.     

Thioflavin T: Electronic Circular Dichroism and Circularly Polarized Luminescence Induced by Amyloid Fibrils

The circularly polarized luminescence (CPL) spectrum of thioflavin T (ThT) bound to insulin amyloid fibrils has been measured for the first time. It has been found that the samples exhibiting induced circular dichroism (CD) retain the optical activity in the CPL spectra, with the same sign of the rotatory strength. The fluorescence dissymmetry factor is substantial (of the order of magnitude 10^?2). Unlike in the corresponding CD and absorption spectra, there is no shift of the CPL band with respect to the fluorescence band. It has been verified that the measured CPL spectra are free from artifacts from circularly polarized scattering of emitted light by conducting additional measurements in a medium with a refractive index similar to insulin (methylsalicylate). The CD and CPL spectra have been interpreted by means of density functional calculations carried out for ThT in its ground and first excited states in different dielectric environments and for ThT interacting with an aromatic ring. It has been found that the presence of an aromatic ring close to the ThT molecule induces Cotton effects of the same order of magnitude as the stabilization of one enantiomeric conformer. Thus, it is expected that both mechanisms contribute to the induced CD and CPL effect to a similar degree.