Lipophilic Cage Ligands: Synthesis, Spectroscopic Properties and Applications

Lipophilic Cage Ligands: Synthesis, Spectroscopic Properties and Application

Ditopic receptors capable of hydrogen bonding: Synthesis and complexation behaviour of diaza crown-ethers having melamine sidearms

The new ditopic receptors 1-3 (Figure 1) have been synthesized and their binding ability for alkaline and transition metal cations has ben investigated by halide and UV-Vis titrations. The recognition of complementary molecules through hydrogen bonding has been studied by H-1-NMR. The simultaneous recognition of these two guests is an anti-cooperative event

Second-generation fluorous chiral (salen) manganese complexes

Sterically hindered chiral (salen)manganese complexes bearing long perfluoroalkyl substituents are synthesized and successfully employed as catalysts in the enantioselective (ee = 50-87%) epoxidation of alkenes under fluorous biphasic conditions

A new tetraoxa-tetraaza macrobicyclic anthracenyl luminescent receptor: control of the receptor-substrate stoichiometry

The luminescent receptor 1 incorporating anthracenyl groups as luminophores and a tetraoxa-tetraaza macrobicyclic receptor as the binding subunit has been synthesized and its interactions with Ca-II, investigated by fluorescence measurements, are reported. The receptor-substrate 1-Ca system is an example of multistability at the molecular level, triggered by a reversible modification of the receptor ability and evidenced by luminescence

Photodegradation of Selected PCBs in the Presence of Nano-TiO2 as Catalyst and H2O2 as an Oxidant

Photodegradation of five strategically selected PCBs was carried out in acetonitrile/water 80:20. Quantum chemical calculations reveal that PCBs without any chlorine on ortho-positions are closer to be planar, while PCBs with at least one chlorine atoms at the ortho-positions causes the two benzene rings to be nearly perpendicular. Light-induced degradation of planar PCBs is much slower than the perpendicular ones. The use of nano-TiO2 speeds up the degradation of the planar PCBs, but slows down the degradation of the non-planar ones. The use of H2O2 speeds up the degradation of planar PCBs greatly (by >20 times), but has little effect on non-planar ones except 2,3,5,6-TCB. The relative photodegradation rate is: 2,2′,4,4′-TCB > 2,3,5,6-TCB > 2,6-DCB ≈ 3,3′,4,4′-TCB > 3,4′,5-TCB. The use of H2O2 in combination with sunlight irradiation could be an efficient and “green” technology for PCB remediation

Constraining the radio properties of the z = 6.44 QSO VIK J2318-3113

The recent detection of the quasi-stellar object (QSO) VIKING J231818.3−311346 (hereafter VIK J2318−3113) at redshift z = 6.44 in the Rapid ASKAP Continuum Survey (RACS) uncovered its radio-loud nature, making it one of the most distant known to date in this class. By using data from several radio surveys of the Galaxy And Mass Assembly 23h field and from a dedicated follow-up, we were able to constrain the radio spectrum of VIK J2318−3113 in the observed range ∼0.110 GHz. At high frequencies (0.8885.5 GHz in the observed frame) the QSO presents a steep spectrum (αr = 1.24, with Sν ∝ ν−αr), while at lower frequencies (0.40.888 GHz in the observed frame) it is nearly flat. The overall spectrum can be modelled by either a curved function with a rest-frame turnover around 5 GHz, or with a smoothly varying double power law that is flat below a rest-frame break frequency of about 20 GHz and above which it significantly steepens. Based on the model adopted, we estimated that the radio jets of VIK J2318−3113 must be a few hundred years old in the case of a turnover, or less than a few × 104 years in the case of a break in the spectrum. Having multiple observations at two frequencies (888 MHz and 5.5 GHz), we further investigated the radio variability previously reported for this source. We found that the marginally significant flux density variations are consistent with the expectations from refractive interstellar scintillation, even though relativistic effects related to the orientation of the source may still play a non-negligible role. Further radio and X-ray observations are required to conclusively discern the nature of this variation

1-Iodo-polyfluoroalkanes from polyfluoroalkoxy trimethylsilanes and iodochloro triphenylphosphorane

Polyfluoroalkoxy trimethylsilanes RfCH2OSi(CH3)3 (from the alcohols RfCH2OH and HMDS), react with Ph3PICl (from ICl and Ph3P) eliminating (CH3)3SiCl. Pyrolysis of the residues gives Ph3PO and pure iodides RfCH2I