Elimination of aspirin and paracetamol from aqueous media using Fe/N-CNT/ß-cyclodextrin nanocomposite polymers: theoretical comparative survey via advanced physical models.

The main purpose of this research is to theoretically investigate the adsorption of two pharmaceutical molecules, i.e. aspirin and paracetamol, using two composite adsorbents, i.e. N-CNT/ß-CD and Fe/N-CNT/ß-CD nanocomposite polymers. A multilayer model developed by statistical physics is implemented to explain the experimental adsorption isotherms at the molecular scale, so as to overpass some limitations of the classical adsorption models. The modelling results indicate that the adsorption of these molecules is almost accomplished by the formation of 3 to 5 adsorbate layers, depending on the operating temperature. A general survey of the number of adsorbate molecules captured by the adsorption site (npm) suggested that the adsorption process of pharmaceutical pollutants is multimolecular and that each adsorption site can capture several molecules simultaneously. Furthermore, the npm values demonstrated the presence of aggregation phenomena of aspirin and paracetamol molecules during adsorption. The evolution of the adsorbed quantity at saturation confirmed that the presence of Fe in the adsorbent enhanced the removal performance of the investigated pharmaceutical molecules. In addition, the adsorption of the pharmaceutical molecules aspirin and paracetamol on the N-CNT/ß-CD and Fe/N-CNT/ß-CD nanocomposite polymer surface involved weak physical type interactions, since the interaction energies do not overcome the threshold of 25 000 J mol-1.

Retraction Note to: Theoretical study of the fragmentation of ionized benzophenone.

The authors have retracted this article [1] due to an error in obtaining permission to use the data generated at the Synchrotron SOLEIL. All authors agree to this retraction.

Addition of tryptophan methyl-ester on [60]fullerene: theoretical investigation of the mechanisms of azomethine ylides and fulleropyrrolidine formation.

In this paper, we perform the synthesization of carbon nanoparticles for active principle vectorization, with the suggestion of a reaction mechanism of tryptophan methyl ester addition on [60]fullerene. Firstly, we studied the effect of tryptophan form on its addition reaction on [60]fullerene. So, in order to determine the preferred environment that makes this reaction the most favorable, we considered all tryptophan possible forms in our investigation: the molecular, the zwitterionic, and the dibasic forms. Secondly, we investigate the proposed reaction mechanism of tryptophan methyl ester addition on [60]fullerene using theoretical thermodynamic calculation. Our hypothesis suggests the formation of azomethine ylide molecule in a first step followed by its addition on [60]fullerene in the second step by the photo-addition reaction involving the oxygen in its singlet state. The stability of each reactive intermediate involved in this mechanism is verified thermodynamically. The 12 most stable conformations of azomethine ylide were observed through potential energy surface analysis. They were obtained by a relaxed scan of the four dihedral angles. The calculations were conducted on the optimized geometry of fulleropyrrolidine mono-adduct and the bulk values of its thermodynamic constants were also determined. Infrared spectra observed in 100-4000 cm-1 region confirmed our hypothesis suggesting the first step of azomethine ylide formation followed by the second step of azomethine ylide addition on [60]fullerene by ν(Caliphatic-C-N), ν(Caromatic-C-N) and δ(N-H) coupled with ν(C-N) absorption bond. Graphical abstract Optimized geometry of the Fulleropyrrolidine monoaduct molecule.

Theoretical study of the fragmentation of ionized benzophenone.

A detailed theoretical study of the various possible fragmentation reactions of the benzophenone radical cation was carried out for the first time. In the first step, we optimized the geometries of all the structures resulting from the fragmentation of this cation using density functional theory (DFT). Our calculations were performed in the gas phase using the aug-cc-pVTZ basis set and the PBE1PBE functional. We determined the optimized structural parameters and the harmonic and anharmonic frequencies. The energies corresponding to all the optimized molecules were recalculated using the coupled cluster method CCSD(T). Upon comparing the fragmentation reaction energies, we found that the principal reaction was that leading to C7H5O+ and ·C6H5. We were able to theoretically demonstrate the existence of different fragments of the benzophenone cation: CO, CO+·, ·C6H5, C6H5+, ·C7H5O, C7H5O+, biphenyl, and (biphenyl)+·, and we found that the main products of the fragmentation reactions of the benzophenone cation are C7H5O+ and (biphenyl)+·, which have been observed experimentally using slow photoelectron spectroscopy (SPES). Our theoretical results are in good agreement with the experimental results from benzophenone cation spectroscopy and fragmentation obtained using Benoît Soep's equipment at Synchrotron SOLEIL.

Photoionization of Benzophenone in the Gas Phase: Theory and Experiment.

We report on the single photoionization of jet-cooled benzophenone using a tunable source of VUV synchrotron radiation coupled with a photoion/photoelectron coincidence acquisition device. The assignment and the interpretation of the spectra are based on a characterization by ab initio and density functional theory calculations of the geometry and of the electronic states of the cation. The absence of structures in the slow photoelectron spectrum is explained by a congestion of the spectrum due to the dense vibrational progressions of the very low frequency torsional mode in the cation either in pure form or in combination bands. Also a high density of electronic states has been found in the cation. Presently, we estimate the experimental adiabatic and vertical ionization energy of benzophenone at 8.80 ± 0.01 and 8.878 ± 0.005 eV, respectively. The ionization energy as well as the energies of the excited states are compared to the calculated ones.

Ab initio investigation of electronic properties of the magnesium hydride molecular ion.

In this work, adiabatic potential energy curves, spectroscopic constants, dipole moments, and vibrational levels for numerous electronic states of magnesium hydride molecular ion (MgH(+)) are computed. These properties are determined by the use of an ab initio method involving a nonempirical pseudopotential for the magnesium core (Mg), the core polarization potential (CPP), the l-dependent cutoff functions and the full valence configuration interaction (FCI). The molecular ion is thus treated as a two-electron system. Our calculations on the MgH(+) molecular ion extend previous theoretical works to numerous electronic excited states in the various symmetries. A good agreement with the available theoretical and experimental works is obtained for the spectroscopic constants, the adiabatic potential energy curves, and the dipole moments for the lowest states of MgH(+).