New [g]-fused [1,2,4]triazolo[1,5-c]pyrimidines: Synthesis of pyrido[3,2-e] and [4,3-e][1,2,4]triazolo[1,5-c]pyrimidine,pyrimido[5,4-e][1,2,4]triazolo[1,5-c]pyrimidine and [1,2,4]triazolo[1,5-c]pteridine derivatives

A number of 2-aryl-substituted pyrido[3,2-e] and [4,3-e][1,2,4]triazolo[1,5-c]pyrimidines and [1,2,4]triazolo[1,5-c]pteridines 11,12a,b,e , their corresponding 5-carbonyl derivatives 7,8a,b,e and some pyrimido[5,4-e][1,2,4]triazolo[1,5-c]pyrimidin-5-ones 7,8c,d have been synthesized, according to different pathways. The new tricyclic heterocycles were prepared with the aim of studying their possible benzodiazepine receptors affinity.     

A simplified integral equation for adsorption of gas mixtures on heterogeneous surfaces

Summary The multiple integral representing the overall isotherm for adsorption of gas mixtures on heterogeneous surfaces is transformed to a single integral, which is promising for predicting the mixed-gas adsorption by means of single-gas adsorption parameters. This transformation is possible when the adsorption energies of components for various adsorption sites show a certain type of correlation.

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Eine vereinfachte Integralgleichung für die Adsorption von Gasmischungen auf heterogenen Oberflächen

Zusammenfassung Das multiple Integral, das die Adsorption von Gasmischungen auf heterogenen Oberflächen darstellt, wurde zu einem einfachen Integral transformiert, das zur Voraussage der Adsorption von Gasgemischen mittels der Einzelgas-Adsorptionsparameter geeignet sein sollte. Diese Transformation ist dann möglich, wenn die Adsorptionsenergien der Komponenten einem bestimmten Korrelationstyp angehören.

     

About the synthesis of N-1-substituted 3-aminopyrroles. A comparison

A general method for the preparation of 3-amino-1-methylpyrroles in excellent yields is reported. The key step involves the N-methylation of the nitro derivatives 2 , under phase transfer catalysis conditions.     

Quantitative Structure–Retention Relationships as Useful Tool to Characterize Chromatographic Systems and Their Potential to Simulate Biological Processes

Quantitative structure–retention relationships (QSRR) date back to the 1970s and are associated with the evolution of modern Chromatography, while in conjunction with quantitative structure–property relationships (QSPR), they make part of the QSAR discipline. The present review offers a survey of QSRR from a medicinal chemistry point of view, highlighting the merits of this approach in exploiting the friendly chromatographic techniques for the establishment of the physico chemical profiling of drug and drug candidates. It starts with a short overview on QSRR methodology concerning molecular representation, statistical tools and model validation. It continues focusing on the major recent achievements of QSRR with regard to the characterization of chromatographic systems and thereupon to the improvement of stationary phases and to experimental design, while emphasizing their application in drug design. The inter-relation of retention with lipophilicity, a property of paramount interest in drug action and the merit of biomimetic chromatography and of MEEKC systems to simulate essential pharmacokinetic properties are commented under the insights offered by QSRR, in conjunction with QSPR. Characteristic examples are discussed.     

Double photoionisation spectra of small molecules and a new empirical rule for double ionisation energies

Complete double photoelectron spectra are presented for 18 small molecules where the location of charges in the cations and dications is relatively clearly defined. The data demonstrate the importance of a coulombic repulsion contribution to the double ionisation energies. Examination of data for a wide range of molecules leads to a new empirical rule to calculate double ionisation energies from the molecules’ single ionisation energies and maximum dimensions. Where single and double ionisation energies are known the rule allows the deduction of plausible intercharge distances.     

Intrinsically flame retardant epoxy resin - Fire performance and background - Part I

The flame retardant effect of newly synthesized phosphorus-containing reactive amine, which can be used both as crosslinking agent in epoxy resins and as a flame retardant, was investigated. The effect of montmorillonite and sepiolite additives on the fire induced degradation was compared to pristine epoxy resin. The effect of combining the organophosphorous amine with clay minerals was also studied. It could be concluded that the synthesized phosphorus-containing amine, TEDAP can substitute the traditional epoxy resin curing agents providing additionally excellent flame retardancy: the epoxy resins flame retarded this way reach 960 °C GWFI value, 33 LOI value and V-0 UL-94 rating - compared to the 550 °C GWFI value, 21 LOI value and “no rate” UL-94 classification of the reference epoxy resin. The peak of heat release was reduced to 1/10 compared to non-flame retarded resin, furthermore a shift in time was observed, which increases the time to escape in case of fire. The flame retardant performance can be further improved by incorporating clay additives: the LOI and the HRR results showed that the optimum of flame retardant effect of clay additives is around 1 mass% filler level in AH-16-TEDAP system. Applying a complex method for mechanical and structural characterization of the intumescent char it was determined that the flame retarded system forms significantly more and stronger char of better uniformity with smaller average bubble size. Incorporation of clay additives (owing to their bubble nucleating activity) results in further decrease in average bubble diameter.     

Dyson orbitals for ionization from the ground and electronically excited states within equation-of-motion coupled-cluster formalism: theory, implementation, and examples

Implementation of Dyson orbitals for coupled-cluster and equation-of-motion coupled-cluster wave functions with single and double substitutions is described and demonstrated by examples. Both ionizations from the ground and electronically excited states are considered. Dyson orbitals are necessary for calculating electronic factors of angular distributions of photoelectrons, Compton profiles, electron momentum spectra, etc, and can be interpreted as states of the leaving electron. Formally, Dyson orbitals represent the overlap between an initial N-electron wave function and the N-1 electron wave function of the corresponding ionized system. For the ground state ionization, Dyson orbitals are often similar to the corresponding Hartree-Fock molecular orbitals (MOs); however, for ionization from electronically excited states Dyson orbitals include contributions from several MOs and their shapes are more complex. The theory is applied to calculating the Dyson orbitals for ionization of formaldehyde from the ground and electronically excited states. Partial-wave analysis is employed to compute the probabilities to find the ejected electron in different angular momentum states using the freestanding and Coulomb wave representations of the ionized electron. Rydberg states are shown to yield higher angular momentum electrons, as compared to valence states of the same symmetry. Likewise, faster photoelectrons are most likely to have higher angular momentum.     

Solvothermal Synthesis and Structures of Lamellar [Mn(tren)2]Cl2 and the Dimeric and Polymeric Hexaselenidomanganese(II) Complexes [{Mn(Se6)(tren)}2] and $^{2}_{\infty}\rm [\{Mn(Se_{6})(tren)\}]$

Reaction of [MnCl₂(tren)] with tren (tris‐(2‐aminoethyl)amine) affords the coordination polymer ( 1 ), in which the primary amino groups of tridentate tren ligands connect [(tren)Mn]²⁺ fragments into a pseudo 6³ network. The Mn atoms exhibit a capped octahedral environment with the tertiary N atom of the second tetradentate tren ligand in the capping position. Treatment of MnCl₂ with Se at 1:2 molar ratio in H₂O/tren (10:1) at 150 °C leads to formation of the dinuclear complex [{Mn(μ‐Se₆)(tren)}₂] ( 2 ), which contains tetradentate tren ligands and two bridging hexaselenide ligands in the 1κSe¹ : 2κSe⁶ mode. In contrast, reaction of [MnCl₂(tren)] with Se at a 1:6 molar ratio under similar sovothermal conditions affords the isomeric coordination polymer ( 3 ). In this complex, Se₆^2? anions now bridge [(tren)Mn]²⁺ fragments into chains, that themselves are linked into polymeric sheets through one of the primary amino groups of the tetradentate tren ligands.