Publications

Abstract The authors regret the existence of an error on one of the results reported in the original and published manuscript. The error has been identified and rectified as follows: • In Abstract, page 2469: the half-life period of “23.8 ± 0.6 s” should be read as “47.6 ± 1.1 s”. • In page 2472, section Results and discussion, second paragraph: the half life was “23.8 ± 0.6 s” should be read as “47.6 ± 1.1 s”. • In page 2478, section Conclusions, first paragraph: the half life period of “23.8 ± 0.6 s” should be read as “47.6 ± 1.1 s”. The authors would like to apologise for any inconvenience caused to the editorial staff and the editor of the Journal of Environmental Chemical Engineering, as well as all its valuable readers and followers.

Abstract UV photodecomposition of azidomethyl methyl sulfide (AMMS) yields a transient S-methylthiaziridine which rapidly evolves to S-methyl-N-sulfenylmethanimine at 10 K. This species was detected by infrared matrix isolation spectroscopy. The mechanism of the photoreaction of AMMS has been investigated by a combined approach, using low-temperature matrix isolation FTIR spectroscopy in conjunction with two theoretical methods, namely, complete active space self-consistent field and multiconfigurational second-order perturbation. The key step of the reaction is governed by a S-2/S-1 conical intersection localized in the neighborhood of the singlet nitrene minimum which is formed in the first reaction step of the photolysis, that is, N-2 elimination from AMMS. Full assignment of the observed infrared spectra of AMMS has been carried out based on comparison with density functional theory and second-order perturbation Moller-Plesset methods.

Abstract Pharmaceuticals are invaluable tools for the prevention and treatment of human and animal diseases. Human evolution led to the increase of life expectancy, which promoted the increase of consumption of pharmaceuticals. These compounds are consistently detected in superficial waters, and whilst degradation processes are expected to mitigate their levels, they also induce the formation of potentially harmful by-products. The compounds studied in this work were acetaminophen, 17 alpha-ethynylestradiol and carbamazepine. High-performance liquid chromatography coupled with ultraviolet diode-array detection was used to follow the degradation reactions, whilst liquid chromatography associated with ultraviolet diode-array detection and mass spectrometry was applied in the determination of by-products. Ethynylestradiol proved to be the most reactive (t(1/2) = 38.6 +/- 1.9 seconds) and carbamazepine the least reactive (t(1/2) = 481.4 +/- 16.7 minutes) when exposed to active chlorine. In relation to disinfection by-products, two monochlorinated analogues were detected for acetaminophen, one monochlorinated for carbamazepine, and one mono- and one trichlorinated for ethynylestradiol. Chlorine levels and water pH proved to be the most influential variables on the degradation of the compounds, with and without dissolved organic matter in solution. All pharmaceuticals displayed significant photostability towards artificial solar radiation, with acetaminophen being slightly more stable.

Abstract <p>A greener and efficient one-pot methodology for the assembly of Glypromate® and its structurally-related analogues by tandem sequential peptide coupling.</p>

Abstract This work reports the role of different dispersants, namely, polyethylene glycol (PEG 200 2%), ethylene glycol 5%, ethanol 2%, dimethyl sulfoxide (DMSO 5%), and polyvinyl alcohol (PVA 5%) in the toxicity profile of several commercial nanomaterials (NM), such as hydrophilic and hydrophobic TiO2, hydrophilic SiO2, SiO2 in aqueous suspension (aq), and ZnO towards the bioluminescent bacterium Aliivibrio fischeri. The majority of NM showed tendency to form agglomerates in the different dispersants. Although some particle agglomeration could be detected, DMSO at 5% was the best dispersant for hydrophobic TiO2 NM while PVA at 5% was the most effective dispersant for the other types of NM. Average size was not the most relevant aspect accounting for their toxicity. A remarkable reduction in average size was followed by a decrease in NM toxicity, as demonstrated for SiO2 aq. in PVA 5%. Contrarily, despite of high particle agglomeration, ZnO NM showed a higher toxicity to bacteria when compared with other tested NM. Independently of the average particle size or surface charge, the dispersant either enhanced the toxicity to bacteria or acted as physical barrier decreasing the NM harmful effect to A. fischeri.

Abstract The efficiency and associated environmental impacts of different N-doping strategies of carbon dots (CDs) were evaluated. More specifically, N-doped CDs were prepared from citric acid via two main synthesis routes: Microwave-assisted hydrothermal treatment with addition of N-containing small organic molecules (urea and ethylenediamine (EDA)); and microwave-assisted solvothermal treatment in N-containing organic solvents (n,n-dimethylformamide (DMF), acetonitrile and pyridine). These syntheses produced CDs with similar blue emission. However, XPS analysis revealed that CDs synthesized via both hydrothermal routes presented a better N-doping efficiency (15 at.%) than all three solvothermal-based strategies (0.6-7 at.%). However, from the former two hydrothermal strategies, only the one involving EDA as a nitrogen-source provided a non-negligible synthesis yield, which indicates that this should be the preferred strategy. This conclusion was supported by a subsequent life cycle assessment (LCA) study, which revealed that this strategy is clearly the most sustainable one from all five studied synthesis routes.

Abstract The study of sensing materials to the detection of carbon dioxide (CO2) was achieved using p-nitrophenol (pNPh) as a colorimetric indicator. The sensing material was polymerized (NPLn), functionalized with 3-triethoxysilyl propyl isocyanate (IPTES) which sensitivity was tested in the form of a membrane as is and encapsulated in hollow silica nanoparticles. The sensing membranes were tested in a closed gas system comprising very precise flow controllers to deliver different concentrations of CO2 (vs. N2). The combination of the sensing membranes with multimode optical fibers and a dual-wavelength diode (LED) allows the measurement of the CO2 through the analysis of the induced absorbance changes with a self-referenced ratiometric scheme. The analysis of the sensing materials have shown significant changes in their chemical and physical properties and the results attest these materials with a strong potential for assessing CO2 dynamics in environmental, medical, and industrial applications.

Abstract Adenosine receptors participate in many physiological functions. Molecules that may selectively interact with one of the receptors are favorable multifunctional chemical entities to treat or decelerate the evolution of different diseases. 3-Arylcoumarins have already been studied as neuroprotective agents by our group. Here, differently 8-substituted 3-arylcoumarins are complementarily studied as ligands of adenosine receptors, performing radioligand binding assays. Among the synthesized compounds, selective A(3) receptor antagonists were found. 3-(4-Bromophenyl)-8-hydroxycoumarin (compound 4) displayed the highest potency and selectivity as A(3) receptor antagonist (K-i = 258 nM). An analysis of its X-ray diffraction provided detailed information on its structure. Further evaluation of a selected series of compounds indicated that it is the nature and position of the substituents that determine their activity and selectivity. Theoretical modeling calculations corroborate and explain the experimental data, suggesting this novel scaffold can be involved in the generation of candidates as multitarget drugs.

Abstract The impact of fullerene side chain functionalization with thiophene and carbazole groups on the device properties of bulk-heterojunction polymer:fullerene solar cells is discussed through a systematic investigation of material blends consisting of the conjugated polymer poly[(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3'"-di(2-octyldodecyl)-2,2 ' ;5 ' ,2 '' ;5 '' ,2'"-quaterthiophen-5,5'"-diyl)] (PffBT4T-2OD) as donor and C-60 or C-70 fulleropyrrolidines as acceptors. The photovoltaic performance clearly depended on the molecular structure of the fulleropyrrolidine substituents although no direct correlation with the surface morphology of the photoactive layer, as determined by atomic force microscopy, could be established. Although some fulleropyrrolidines possess favorable lowest unoccupied molecular orbital levels, when compared to the standard PC71BM, they originated OPV cells with inferior efficiencies than PC71BM-based reference cells. Fulleropyrrolidines based on C-60 produced, in general, better devices than those based on C-70, and we attribute this observation to the detrimental effect of the structural and energetic disorder that is present in the regioisomer mixtures of C-70-based fullerenes, but absent in the C-60-based fullerenes. These results provide new additional knowledge on the effect of the fullerene functionalization on the efficiency of organic solar cells.

Abstract The synthesis of noble metal nanoparticles (i.e., silver and gold) for electrochemical applications has been widely studied using mainly wet synthesis chemical methods or electrochemical deposition methods. In this work, we propose a single-step flash photochemical method for synthesizing noble metal nanoparticles (i.e., silver, gold, and Au:Ag) in solution for electrochemical applications. The method is based on the intense pulsed radiation emitted from a xenon flashlamp, which induce the reduction of metal cations in solution to form metallic nanoparticles. The present method is based on the selective light absorption of the metal precursor salts combined with the decomposition of polyvinylpyrrolidone added to the solution. This approach can be termed as flash light synthesis.