Thermal,spectral and biological characterisation of copper(II) complexes with isoniazid-based hydrazones

Journal of Thermal Analysis and Calorimetry - A series of complexes [Cu(L)(CH3COO)2]·nH2O (L: isonicotinic acid 2-(2-hydroxy-8-substituted-tricyclo[7.3.1.02.7]tridec-13-ylidene)-hydrazones)...     

Compact dielectric particles as a building block for low-loss magnetic metamaterials

We characterize experimentally a compact dielectric particle that can be used to design very low-loss artificial electromagnetic materials (metamaterials). Focusing on magnetic media, we show that the particle can behave almost identically to the well-known split-ring resonators (SRRs) widely used in present designs, without suffering from the Ohmic losses that can limit the applicability of SRRs especially at high frequencies. We experimentally compare qualitatively and quantitatively the dielectric particle with a typical split-ring resonator of the same size built on a low-loss dielectric substrate and show that at GHz frequencies the quality factor of the dielectric particle is more than 3 times bigger than that of its metallic counterpart. Low-loss and simple geometry are significant advantages compared to conventional metal SRRs.     

Click-evoked potentials in a large marine mammal, the adult male northern elephant seal (Mirounga angustirostris)

Auditory evoked potential (AEP) hearing studies in marine mammals should consider an expected size-dependent reduction in AEP amplitude. This study is the first to measure the click-evoked response in a large marine mammal, the adult male elephant seal (Mirounga angustirostris). Click stimuli were presented at peak-peak equivalent sound pressure levels of 117-118 dB re: 20 microPa. Three positive peaks (P1-P3) and two negative peaks (N4 and N5) were observed in the AEP. Response latencies were longer than previously observed in a 1.8 yr old seal and the maximum peak-peak amplitude was comparatively reduced by more than 60%. The inverse relationship between size and AEP amplitude will likely require increased averaging with larger subjects and possibly modifications to electrode placement and design in order to increase the quality of recorded evoked responses.     

Preparation of core–shell nanospheres of silica–silver: SiO2@Ag

We prepared SiO₂@Ag core–shell nanospheres: silver nanoparticles (～4 ± 2 nm in diameter) coated silica nanospheres (～50 ± 10 nm in diameter). The preparation route is a modification of the Stöber method, and involves the preparation of homogeneous silica spheres at room temperature, combined with the deposition of silver nanoparticles from Ag⁺ in solution, by using water/ethanol mixtures, tetraethyl-orthosilicate as Si source and silver nitrate as Ag source in a single-pot wet chemical route without an added coupling agent or surface modification, which leads to the formation of core@shell homogeneous nanospheres. We present the preparation and characterization of the SiO₂@Ag core–shell nanospheres and also of bare silica spheres in the absence of silver, and propose a reaction mechanism for the formation of the core–shell structure.     

Triphenylene: A versatile molecular receptor

Since the late seventies, the search for new molecular receptors has been constant in perfecting the affinity and selectivity of recognition in different media. At present, a renewed interest in (host:guest) chemistry focuses on the molecular detection of specific targets such as biological, pollutant, toxic or explosive species. This review of triphenylene-based receptors outlines their recent contribution to molecular recognition. Two main structural approaches were investigated to transform a simple triphenylene moiety into a host for neutral aromatic compounds or cations, by tailoring multivalent molecules provided with or without a flatten cavity. The properties of different receptors are presented along with the latest synthetic methods to prepare high-value triphenylenes and the perspectives in the field of sensing. In addition, the role of functionalized triphenylenes in extended (host:guest) systems is illustrated by the main examples of discotic liquid crystals and porous coordination polymers involving this polyaromatic compound.     

Unsaturated four-membered N-heterocycles: From synthesis to applications

The ubiquity of strained motifs in drug discovery has recently witnessed a large regain of interest, as such scaffold can be used to modulate the properties of drug candidates. Unsaturated N-containing four-membered heterocycles present unique opportunities to access functionalized azetidines, which play an essential role in pharmacological studies. Even though those unsaturated patterns have been much less reported than the corresponding saturated versions, the consequent impact that those structures could have on molecular design with implementation of strained modules deserves to be summarized. In this review, synthetic accesses to substituted azetes, 1-azetines and 2-azetines are depicted, as well as their involvement in further transformations.     

Effect of the amine type on thermal stability of modified mesoporous silica used for CO2 adsorption

In this study, the preparation by grafting of amino-functionalized SBA-15 molecular sieves was carried out. Amino-functionalized molecular sieves were synthesized using a silane coupling agent and different types of amination reagents which react with modified SBA-15. These composites were characterized by FT-IR spectroscopy, X-ray diffraction at low angles, nitrogen physisorption at 77 K, and evaluated by the adsorption of CO₂ and its temperature-programmed desorption—TPD. Thermal stability was investigated by TGA and DTA methods. In the view of a possible use of these amino-functionalized molecular sieves as sorbents for CO₂ removal, their adsorption–desorption properties towards CO₂ were also investigated by the TPD method. The mass loss of amino-functionalized molecular sieves above 215 °C was due to the oxidation and decomposition of amino propyl functional groups. This means that these composites could be used for adsorption of CO₂ at temperatures below 215 °C. The adsorption of CO₂ and its temperature programmed desorption using thermogravimetry were studied for amino-functionalized molecular sieves at 60 °C. The evolved gases during the adsorption–desorption of CO₂ on amino-functionalized molecular sieves were identified by online mass spectrometry coupled with thermogravimetry. CO₂ adsorption isotherms of functionalized samples at 60 °C showed that both the adsorption capacity (mg CO₂/g adsorbent) and the efficiency of amino groups (mol CO₂/mol NH₂) depend on the type of amination reagents and the amount of organic compound used.

     

Amalgamated free products of weakly rigid factors and calculation of their symmetry groups

We consider amalgamated free product II₁ factors M = M _1*B M _2*B … and use “deformation/rigidity” and “intertwining” techniques to prove that any relatively rigid von Neumann subalgebra Q ⊂ M can be unitarily conjugated into one of the M _i ’s. We apply this to the case where the M _i ’s are w-rigid II₁ factors, with B equal to either C, to a Cartan subalgebra A in M _i , or to a regular hyperfinite II₁ subfactor R in M _i , to obtain the following type of unique decomposition results, àla Bass–Serre: If M = (N _1 * CN_2*C …) ^t , for some t > 0 and some other similar inclusions of algebras C ⊂ N _i then, after a permutation of indices, (B ⊂ M _i ) is inner conjugate to (C ⊂ N _i ) ^t , for all i. Taking B = C and , with {t _i } _i⩾1 = S a given countable subgroup of R ₊ ^*, we obtain continuously many non-stably isomorphic factors M with fundamental group equal to S. For B = A, we obtain a new class of factors M with unique Cartan subalgebra decomposition, with a large subclass satisfying and Out(M) abelian and calculable. Taking B = R, we get examples of factors with , Out(M) = K, for any given separable compact abelian group K.     

226Ra translocation from soil to selected vegetation in the Crucea (Romania) uranium mining area

A two year field survey of ²²⁶Ra translocation from soil to selected spontaneous plants growing in the Crucea (Romania) uranium mining area is presented. Since Crucea is a large and relatively highly contaminated area, an easy and cheap way for a desired lowering of radiopollution represents phytoremediation using plentifully occurring plant species. The ²²⁶Ra translocation from soil was affected by analyzed species, collecting sites and vegetation periods. The specific ²²⁶Ra activities of the roots were considerably higher than the aboveground parts confirming the root tropism of radioisotopes. Mentha piperita was found to be highly effective in phytoremediation, especially in autumn.     

The first platinum(IV) complexes involving aromatic cytokinins or cyclin-dependent kinase inhibitors derived from 6-benzylaminopurine: X-ray structures of

A series of Pt(IV) complexes with cytokinins or CDK-inhibitors derived from 6-benzylaminopurine (Bap) of the composition [Pt^IV(LH⁺)Cl₅] (1–14), where LH⁺ stands for protonated form of the Bap derivative (1–12), Boh = 6-(benzylamino)-2-[(3-hydroxypropyl)amino]-9-isopropylpurine, bohemine (13) and Ros = 6-(benzylamino)-2-[(1-hydroxymethylpropyl)amino]-9-isopropylpurine, roscovitine (14), have been prepared.They have been fully characterized by microanalysis, conductivity, FT-IR, ¹H, ¹³C, ¹⁵N and ¹⁹⁵Pt NMR and ES+ mass spectroscopy.It has been found that the cytokinin molecule is coordinated via N9 atom to platinum(IV) and N1, N7-protonated in case of complexes 1–12, and N7 coordinated and N1-protonated in case of complexes with CDK inhibitors (13 and 14).Predicted molecular geometries of the complexes have been supported by DFT calculations at the B3LYP level with the 6-311+G^**/LANL2DZ and aug-cc-pVDZ/LANL2DZ basis sets.All of the compounds have been tested in vitro for their cytotoxicity against four human cancer cell lines: malignant melanoma (G361), osteogenic sarcoma (HOS), chronic myelogenous erythroleukemia (K562) and breast adenocarcinoma (MCF7).The best result has been achieved for complex 14, where IC₅₀ = 17 μM against K562. The molecular structures of two ionic pair compounds have been determined by a single crystal X-ray analysis.