TFA-catalysed tandem double cyclisation: A one-pot,metal-free routes for novel indolo-imidazo[1,2-a]pyridine derivatives

A transition-metal free, one-pot tandem synthetic routes for novel indole and imidazo[1,2-a]pyridine derivative hybrids have been established. An efficient three-component reaction was designed with incorporation of two sequential Groebke–Blackburn–Bienayme (GBB) and cyclization reaction in one-pot under mild acidic condition. The salient feature of this protocol is atom economy, good yield and operational simplicity. A molecular prospective library of 32 compounds was synthesized by utilizing the various substituted aryl aldehydes and 2-aminopyridine.     

Detection of equimolar EDTA and DTPA in spiked wastewater effluents

Ethylenediaminetetraacetic acid (EDTA) and diethylenetriamine-pentaacetic acid (DTPA) are water ‘softening’ agents that are present in numerous household and industrial detergents. Since these particular chelating agents are not significantly degraded during conventional wastewater treatment processes, wastewater treatment plant (WTP) effluents can contain up to 19 µM of EDTA and 7 µM of DTPA. Little, however, is known about the release of EDTA and DTPA from WTPs to rivers. To gain insight, we here report on the development of a cost-effective analytical method. This method is based on the chromatography of a humic acid-cadmium (HA-Cd) complex on a size-exclusion chromatography column (SEC, Sephadex G-15) while using WTP effluents from Lethbridge, Banff and Canmore which contained 10 mM Tris-buffer as the mobile phase (pH 8.2). The intact HA-Cd complex is detected by means of a flame atomic absorption spectrometer (FAAS). The addition of equimolar EDTA and DTPA up to 10 µM allowed us to observe a concentration-dependent increase of the retention time of the main Cd-peak. This behaviour was qualitatively comparable between the WTP effluents and was rationalised by the EDTA/DTPA-mediated mobilisation of Cd from the HA-Cd complex. The signal intensity that corresponded to the mobilised Cd was used to establish calibration curves with corresponding correlation coefficients in the range of 0.950–0.978. Therefore, the developed method yields robust results for realistic concentrations of equimolar EDTA/DTPA in real WTP effluents. The developed method can now be applied to analyse real WTP effluent for the presence of chelating agents, whose concentrations may be expressed as being equivalent to a particular equimolar EDTA/DTPA concentration.     

Detecting Embedded Networks in LP Using GUB Structures and Independent Set Algorithms

In this paper, we present an alternative multi-stage generalized upper bounds (GUB) based approach for detecting an embedded pure network structure in an LP problem. In order to identify a GUB structure, we use two different approaches; the first is based on the notion of Markowitz merit count and the second exploits independent sets in the corresponding graphs. Our computational experiments show that the multi-stage GUB algorithm based on these approaches performs favourably when compared with other well known algorithms.     

4‐Ethynyl‐4‐hydroxycyclohexan‐1‐one and 4‐ethynyl‐4‐hydroxy‐2,3,5,6‐tetramethylcyclohexa‐2,5‐dien‐1‐one

The title compounds, C₈H₁₀O₂, (I), and C₁₂H₁₄O₂, (II), occurred as by‐products in the controlled synthesis of a series of bis­(gem‐alkynols), prepared as part of an extensive study of synthon formation in simple gem‐alkynol derivatives. The two 4‐(gem‐alkynol)‐1‐ones crystallize in space group P2₁/c, (I) with Z′ = 1 and (II) with Z′ = 2. Both structures are dominated by O—H?O=C hydrogen bonds, which form simple chains in the cyclo­hexane derivative, (I), and centrosymmetric dimers, of both symmetry‐independent mol­ecules, in the cyclo­hexa‐2,5‐diene, (II). These strong synthons are further stabilized by C[triple‐bond]C—H?O=C, C_methylene—H?O(H) and C_methyl—H?O(H) interactions. The direct intermolecular interactions between donors and acceptors in the gem‐alkynol group, which characterize the bis­(gem‐alkynol) analogues of (I) and (II), are not present in the ketone derivatives studied here.     

Benzyltriphenylphosphonium gluta­conaldehyde

The title compound, C₂₅H₂₂P⁺·C₅H₅O₂^?, crystallizes in space group P2₁/c. The phospho­nium cations form zigzag chains with P?P distances of 6.475 (1) and 8.287 (2) Å, and are related by inversion centres. Two types of attractive edge‐to‐face phenyl interactions exist, resulting in a dominant supramolecular motif. The glutaconaldehyde anions occupy the interchain spacing and hold adjacent chains together via multiple C—­H?O hydrogen bonds. The bond‐length alternation, a parameter which reveals the non‐linear optical efficiency at the molecular level, is optimized in the chromophore anion.     

Parity of the band head at 3710 keV in 99Rh using clover detector as compton polarimeter

Clover detector has been used as a Compton polarimeter to measure the linear polarization of γ-rays produced in heavy ion fusion reaction. The polarization sensitivity of the clover detector has been measured over γ-ray energies ranging from 386 to 1368 ke V. The E1 multipolarity of the 1117 keV transition in ⁹⁹Rh has been established using this polarimeter. This has resulted in the assignment of negative parity to the band head at 3710 keV in ⁹⁹Rh.     

Two-Neutron Alignment in <Superscript>127</Superscript>Xe

High spin states in ¹²⁷Xe have been investigated via ⁹Be induced fusion-evaporation reaction at 48 MeV. Spin and parity of excited states up to \( \sim \frac {47}{2} \hbar \) have been confirmed from angular correlation and linear polarization results. Rotational alignment of the second pair of h _11/2 neutrons has been observed at \(\hbar \omega \sim \) 0.44 MeV; beyond that, the band is associated with ν[h _11/2]³ configuration. The alignment phenomena has been discussed in comparison with the neighboring ^125,129Xe.     

Role of Barrier Modification and Nuclear Structure Effects in Sub-Barrier Fusion Dynamics of Various Heavy Ion Fusion Reactions

The role of barrier modifications and the relevant nuclear structure effects in the fusion of the \( {}_8{}^{16}O+{}_{62}{}^{144,148,150,152,154}Sm \) and \( {}_3{}^{6,7}Li+{}_{62}{}^{152}Sm \) systems is analyzed within the context of the energy-dependent Woods-Saxon potential model (EDWSP model) and the coupled channel model. For the \( {}_8{}^{16}O+{}_{62}{}^{144,148,150,152,154}Sm \) reactions, where the colliding pairs are stable against breakup, the collective excitations and/or static deformations are sufficient to account for the observed fusion enhancement. In contrast, the model calculations overpredict the complete fusion data at above - barrier energies for the \( {}_3{}^{6,7}Li+{}_{62}{}^{152}Sm \) systems, where the importance of projectile breakup effects has been pointed out. Due to the low threshold of the alpha-breakup channel, the weakly bound projectiles \( \left({}_3{}^{6,7}Li\right) \) break up into charged fragments before reaching the fusion barrier and consequently the complete fusion cross section is suppressed by 28% (25%) in the \( {}_3{}^6Li+{}_{62}{}^{152}Sm\;\left({}_3{}^7Li+{}_{62}{}^{152}Sm\right) \) reaction with respect to predictions of coupled channel calculations. However, the EDWSP model based calculations can minimize the suppression factor by as much as of 13% (8%) in the \( {}_3{}^6Li+{}_{62}{}^{152}Sm\;\left({}_3{}^7Li+{}_{62}{}^{152}Sm\right) \) reaction with reference to the predictions made by the coupled channel calculations. Therefore, the complete fusion data of the \( {}_3{}^6Li+{}_{62}{}^{152}Sm\;\left({}_3{}^7Li+{}_{62}{}^{152}Sm\right) \) reaction at above - barrier energies is reduced by 15% (17%) with respect to the expectations of the EDWSP model. The extracted suppression factors for the studied reactions are due to the modifications of the barrier profile as a consequence of the energy - dependence in nucleus-nucleus potential, and thus greater barrier modifications occur for more weakly bound system, which in turn, confirms the breakup of projectile in the incoming channel.     

Structural basis for bending of organic crystals

Bending is observed in organic crystals when the packing is anisotropic in such a way that strong and weak interaction patterns occur in nearly perpendicular directions.