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Sulfate radicals (SO) reactivity against gram-negative (E. coli) and gram-positive (E. faecalis) bacteria and Contaminants of Emerging Concern (CECs) (Diclofenac-DCF, Sulfamethoxazole-SMX and Trimethoprim-TMP) was investigated through laser flash photolysis (LFP) technique. Analysis of the lifetime of SO in presence of cell-wall compounds of bacteria and CECs allowed determining reactivity of SO towards these compounds. Results showed that SO reacts with common cell-wall components through H-abstraction mechanism (k < 10 Ms). By contrast, k > 10 Ms were found using aromatic amino acids (AAA) only present in Porins of the gram-negative outer-membrane. The intermediates detected from the reaction of SO with the AAA confirmed the involvement of electron transfer processes. Moreover, k values determined for DCF, TMP and SMX also agreed with an electron transfer mechanism. Interestingly, bacteria and CECs removal at pilot plant scale by UV-C/SO is in accordance with the k obtained using the LFP: E. coli > E. faecalis and DCF > TMP ≅ SMX., This work is part of a project that has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreement No 765860 (AQUAlity). Authors also acknowledge the Spanish Ministry of Science and Innovation (Projects PID2019–110441RB-C32 and PID2019–110441RB-C33). PhD Scholarship from CONACYT for J. Flores-Garcia (709358) is acknowledged.

Photosensitized thymine<>thymine (Thy<>Thy) formation and repair can be mediated by carbazole (Cbz). The former occurs from the Cbz triplet excited state via energy transfer, while the latter takes place from the singlet excited state via electron transfer. Here, fundamental insight is provided into the role of the topology and excited state multiplicity, as factors governing the balance between both processes. This has been achieved upon designing and synthesizing different isomers of trifunctional systems containing one Cbz and two Thy units covalently linked to the rigid skeleton of the natural deoxycholic acid. The results shown here prove that the Cbz photosensitized dimerization is not counterbalanced by repair when the latter, instead of operating through-space, has to proceed through-bond., Financial support from the Spanish Government (grant SEV-2016-0683), Generalitat Valenciana (PROMETEO/2017/075 and PROMETEO/2021/077), and Technical University of Valencia (Predoctoral FPI fellowship for P.M.) is gratefully acknowledged. G.S. thanks CTI-CSIC for the use of computational facilities.

Benzotriazole UV-stabilizers (BUVSs) are commonly used in industry as solar filters, due to their strong UV light absorption. Because of their extended usage, environmental contamination of waters due to BUVSs constitutes a growing concern. Direct photodegradation of BUVSs is not efficient due to their intrinsic thermal pathways to release the absorbed light. Nevertheless, their abatement in natural environments could be assisted by chromophoric dissolved organic matter. Among the BUVSs, three representative candidates were selected, UV-326, UV-327 and UV-328, to demonstrate the potential of Riboflavin (RF) as a natural visible-light absorbing photocatalyst for the abatement of these recalcitrant pollutants under reductive conditions. The use of visible light and DABCO, as a model sacrificial electron donor, generates the radical anion RFTA. This key species reacts with the solar filters, achieving their reductive abatement from the medium. Moreover, the participation of every potential reactive species has been investigated by photophysical techniques, together with determination of the quenching rate constant for every reaction pathway. Consequently, evidence supported the main role of the reductive photodegradation pathway, being RFTA the key species in the abatement of BUVSs., This research was funded by H2020/Marie Skłodowska-Curie Actions under the AQUAlity project (Reference: 765860) and European Union's Horizon 2020 Research and Innovation Program under European Research Council (ERC) through the HyMAP project (grant agreement No. 648319). Project PID2019-110441RB-C33 financed by MCIN/AEI/10.13039/501100011033 and AEI-MICINN/FEDER, UE through the Nympha Project (PID2019-106315RB-I00), the regional government of “Comunidad de Madrid” and the European Structural Funds through their financial support to FotoArt-CM project (S2018/NMT-4367) are also acknowledged.

Noscapine (NSC) is a benzyl-isoquinoline alkaloid discovered in 1930 as an antitussive agent. Recently, NSC has also been reported to exhibit antitumor activity and, according to computational studies, it is able to attack the protease enzyme of Coronavirus (COVID-19) and thus could be used as antiviral for COVID-19 pandemic. Therefore, an increasing use of this drug could be envisaged in the coming years. NSC is readily metabolized with a half-life of 4.5 h giving rise to cotarnine, hydrocotarnine, and meconine, arising from the oxidative breaking of the Csingle bondC bond between isoquinoline and phthalide moieties. Because of its potentially increasing use, high concentrations of NSC but also its metabolites will be delivered in the environment and potentially affect natural ecosystems. Thus, the aim of this work is to investigate the degradation of NSC in the presence of naturally occurring photocatalysts. As a matter of fact, the present contribution has demonstrated that NSC can be efficiently degraded in the presence of a derivative of the natural organic dye Riboflavin (RFTA) upon exposure to visible light. Indeed, a detailed study of the mechanism involved in the photodegradation revealed the similarities between the biomimetic and the photocatalyzed processes. In fact, the main photoproducts of NSC were identified as cotarnine and opianic acid based on a careful UPLC-MS2 analysis compared to the independently synthesized standards. The former is coincident with one of the main metabolites obtained in humans, whereas the latter is related to meconine, a second major metabolite of NSC. Photophysical experiments demonstrated that the observed oxidative cleavage is mediated mainly by singlet oxygen in a medium in which the lifetime of 1O2 is long enough, or by electron transfer to the triplet excited state of RFTA if the photodegradation occurs in aqueous media, where the 1O2 lifetime is very short., This work has been partially funded by the European Union, under the Marie Skłodowska-Curie scheme (Grant No 765860, AQUAlity). The Generalitat Valenciana (PROMETEO/2017/075) and the Spanish Government (Grant PID2019-110441RB-C33 financed by MCIN/AEI/10.13039/501100011033) are also gratefully acknowledged.

[EN] Organic photocatalysts could employ visible light to produce photodegradation of pollutants; however, their low photostability prevents their reuse even when they are supported on solid materials. Herein, to obtain a Riboflavin (RF)-based photocatalyst robust and recyclable, RF has been covalently anchored to silica particles, converting the known homogeneous photocatalyst into a new heterogeneous one (SiO2-RF). To enhance the photostability of SiO2-RF, generation of the RF triplet excited state and subsequent singlet oxygen were prevented by ensuring a complete shell of RF moieties on the silica spheres. Moreover, adsorption of organic pollutants such as phenol, ortho-phenylphenol, 2,4,6-trichlomphenol and pentachlorophenol on the surface of SiO2-RF is favored in aqueous media, facilitating electron transfer from the pollutants to the short-lived first singlet excited state of RF. Photophysical measurements provided evidence on the photocatalytic mechanism for SiO2-RF., YY The authors would like to acknowledge H2020/Marie Skodowska-Curie Actions under the AQUAlity project (Reference: 765860) , Con-selleria d'Educacio, Investigacio, Cultura i Esport (PROMETEO/2017/075) , the Spanish Ministry of Science, Innovation and Universities (PID2019-110441RB-C33 and SEV-2016-0683) . O. Cabezuelo is indebted to the Universitat Polite cnica de Valencia for the Predoctoral FPI fellowship (FPI-UPV/Subprograma 1) . R. M.-H. acknowledges Fondo Social Europeo (FSE) 2014-2020 Generalitat Valenciana (APOSTD-2019/124) .

[EN] The attainment of transition-metal catalysis and photoredox catalysis has represented a great challenge over the last years. Herein, we have been able to merge both catalytic processes into what we have called "the light-triggered CuAAC reaction". Particularly, the CuAAC reaction reveals opposite outcomes depending on the nature of the photocatalyst (eosin Y disodium salt and riboflavin tetraacetate) and additives (DABCO, Et3N, and NaN3) employed. To get a better insight into the operating processes, steady-state, time-resolved emission, and laser flash photolysis experiments have been performed to determine reactivity and kinetic data. These results, in agreement with thermodynamic estimations based on reported data, support the proposed mechanisms. While for eosin Y (EY), Cu(II) was reduced by its triplet excited state; for riboflavin tetraacetate (RFTA), mainly triplet excited RFTA state photoreductions by electron donors as additives are mandatory, affording RFTA¿- (from DABCO and NaN3) or RFTAH¿ (from Et3N). Subsequently, these species are responsible for the reduction of Cu(II). For both photocatalysts, photogenerated Cu(I) finally renders 1,2,3-triazole as the final product. The determined kinetic rate constants allowed postulating plausible mechanisms in both cases, bringing to light the importance of kinetic studies to achieve a strong understanding of photoredox processes., We acknowledge financial support from the Spanish Government (SEV-2016-0683), the Spanish Ministry of Science, Innovation, and Universities (Project PID2019-110441RBC33), the Generalitat Valenciana (Prometeo 2017/075), the Generalitat Valenciana, and the European Social Fund for postdoctoral contract (APOSTD2019-124 for R.M.-H.). R.M.H. We would also like to thank the financial support for a predoctoral contract from Apadrina la Ciencia Association and Ford Espana/Ford Motor Company Fund. We also acknowledge INFIQC-CONICET and Universidad Nacional de Cordoba (UNC). This work was partly supported by CONICET, SECyT-UNC, and FONCyT.

[EN] There is a current concern, among the scientific community, on the pollutants classified as "persistent organic pollutants (POPs)". Pharmaceuticals and personal care products (PPCPs) belong to this family of contaminants; therefore, it is necessary to find more efficient techniques able to achieve their removal from the environment. This study focuses on two different pharmaceuticals: carbamazepine and atenolol, chosen for their widespread use and their different chemical and medical properties. In this work, an organic dye, acetylated riboflavin, has been used in combination with visible light to achieve the photodegradation of these two POPs in, Financial support from H2020/Marie SkodowskaCurie Actions under the AQUAlity project (Reference: 765860) , Conselleria d'Educacio, Investigacio, Cultura i Esport (PROMETEO/2017/075) and the Spanish Ministry of Science, Innovation and Universities (PID2019-110441RB-C33) is gratefully acknowledged.

[EN] Oxidative damage to proteins leads to a variety of modifications that are markers of pathogenesis. One of the most important modifications is the dityrosine (Tyr(2)) cross-link, resulting from an oxidative covalent bond between two tyrosines (Tyr). An optimized methodology for preparation of pure Tyr(2) is important to investigate in detail its physicochemical properties and reactivity. Pterin (Ptr), the parent and unsubstituted compound of oxidized pterins, is able to photosensitize the cross-linking of free tyrosine (Tyr) and tyrosine residues of peptides and proteins through a photoinduced electron transfer mechanism. We have optimized a simple, one-step photocatalyzed formation of Tyr(2), using Ptr as photocatalyst. Our procedure is carried out in aqueous solutions under UV-A radiation for few minutes. The purification of Tyr(2) is performed by reverse-phase chromatography. The obtained highly pure solution is used to fully characterize the Tyr(2) (exact mass and H-1, H-1-H-1 COSY; DEPT; HSQC and HMBC NMR experiments) and to deeper study its fluorescence properties. (C) 2017 Elsevier Ltd. All rights reserved., The present work was partially supported by Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET; Grant PIP 0304), Agencia de Promocion Cientifica y Tecnologica (ANPCyT; Grants PICT 2012-0508), and Universidad Nacional de La Plata (UNLP; Grant X586 and X712). L.O.R. and C.C. thanks CONICET for doctoral research fellowships. Funding from the Programa CSIC de Cooperacion Cientifica para el Desarrollo (iCOOPLight project ref 20105CD0017) is gratefully acknowledged. A.H.T. and M.L.D are research members of CONICET. The authors thank Dr. Mariana Vignoni (INIFTA, CONICET) and Nathalie Martins-Froment of the Service Commun de Spectrometrie de Masse (FR2599), Universite de Toulouse III (Paul Sabatier) for their crucial contributions in mass spectrometry measurements.

An organized collection of visible-light photoredox reactions, mainly based on the use of transition-metal photocatalysts, and leading to the preparation of drugs or pharmacophores is presented. Upon generation of radicals, the key step is the formation of new carbon-carbon, carbon-nitrogen or carbon-oxygen bonds. Examples of late stage transformation of heterocycles, benzylic derivatizations, arylation of 5 or 6-membered (hetero) arenes, rearrangements, Michael-like additions, [3+2] cycloadditions, among others are included.

Reductive dehalogenation of organic bromides has been achieved in the presence of riboflavin (RF) as the photocatalyst under visible light irradiation. Specifically, benzyl bromide (2) and -bromoacetophenone (3) were quantitatively converted into toluene and acetophenone, respectively, using amines as electron donors and i-PrOH as H-donor, while bromobenzene (1) remained unreacted. The thermodynamics of the reduction reaction from the radical anion of RF was evaluated using the redox potentials of the involved species: while it is not expected for bromobenzene (1), is thermodynamically exergonic for 2 and 3. The viability of the different competing processes in the time scale of the corresponding singlet and triplet RF excited states (1RF* and 3RF*), was analyzed by time-resolved techniques. Quenching of 1RF* by amines was very efficient, and the comparison of the transient absorption spectrum recorded in the absence and in the presence of amines acted as an additional confirmation of the efficient redox process from 1RF*. Moreover, quenching of RF._ was observed for bromides 2 and 3, while 1 did not produce any change. Thus, deeper understanding of the overall mechanism of a photocatalytic reductive reaction has been achieved, and the key role of the radical anion of the photocatalyst has been demonstrated.

[EN] A photoactive bathymeter based on a carboxylic acid moiety covalently linked to a signalling methoxynaphthalene (MNP) fluorophore has been designed to prove the concept of "snorkelling" vs. "diving" in mixed micelles (MM). The carboxylic acid "floats" on the MM surface, while the MNP unit sinks deep in MM. The rate constants of MNP fluorescence quenching by iodide, which remains basically in water, consistently decrease with increasing spacer length, revealing different regions. This is associated with the distance MNP should "dive" in MM to achieve protection from aqueous reactants. Unequivocal proof of the exergonic photoinduced electron transfer was obtained from the UV-visible spectral signature of I-3(-) upon steady-state photolysis. The applicability of the bathymeter was examined upon testing a family of MNP derivatives. The obtained results were validated by comparison with different lipophilicity tests: (i) a modified version of the K-ow partition coefficient and (ii) the retention factor on thin layer chromatography. This concept could potentially be extended to test drugs or pharmacophores exhibiting any photoactive moiety., Financial support from the Spanish Government (SEV-2016-0683), Red RETICS de Investigacion de Reacciones Adversas a Alergenos y Farmacos (RIRAAF), Instituto de Salud Carlos III (RD012/0013, RD16/0006/0030, FIS PI16/01877), VLC-Campus and the Generalitat Valenciana (Prometeo Program) is gratefully acknowledged.

[EN] A mechanistic study is herein presented for the use of heterogeneous photocatalysts based on perylene moieties. First, the successful immobilization of perylene diimides (PDI) on silica matrices is demonstrated, including their full characterization by means of electronic microscopy, surface area measurements, powder XRD, thermogravimetric analysis, and FTIR, Si-29 and C-13 solid-state NMR, fluorescence, and diffuse reflectance spectroscopies. Then, the photoredox activity of the material was tested by using two model reactions, alkene oxidation and 4-nitrobenzylbromide reduction, and mechanistic studies were performed. The mechanistic insights into their photoredox activity show they have promising dual photocatalytic activity for both organic oxidations and reductions., This work was supported by the Natural Sciences and Engineering Research Council of Canada and the Canada Foundation for Innovation. The authors are grateful to Prof. J.C. Scaiano for his generous support.

Benzophenone (BP) and drugs containing the BP chromophore, such as the non-steroidal anti-inflammatory drug ketoprofen, have been widely reported as DNA photosensitizers through triplet–triplet energy transfer (TTET). In the present work, a direct spectroscopic fingerprint for the formation of the thymine triplet ( Thy*) by through-bond (TB) TTET from BP* has been uncovered. This has been achieved in two new systems that have been designed and synthesized with one BP and one thymine (Thy) covalently linked to the two ends of the rigid skeleton of the natural bile acids cholic and lithocholic acid. The results shown here prove that it is possible to achieve triplet energy transfer to a Thy unit even when the photosensitizer is at a long (nonbonding) distance., Financial support from the Spanish Government (Grant SEV‐2016‐0683 and Projects CTQ2012‐38754‐C03‐03 and CTQ2015‐70164P), the Generalitat Valenciana (Prometeo Program), and the Universitat Politècnica de València (pre‐doctoral FPI fellowship for P.M.) is gratefully acknowledged.

The photochemical reactivity of the triplet state of pyrano- and furano-1,4-naphthoquinone derivatives (1 and 2) has been examined employing nanosecond laser flash photolysis. The quinone triplets were efficiently quenched by l-tryptophan methyl ester hydrochloride, l-tyrosine methyl ester hydrochloride, N-acetyl-l-tryptophan methyl ester and N-acetyl-l-tyrosine methyl ester, substituted phenols and indole (k ∼10 L mol s ). For all these quenchers new transients were formed in the quenching process. These were assigned to the corresponding radical pairs that resulted from a coupled electron/proton transfer from the phenols, indole, amino acids, or their esters, to the excited state of the quinone. The proton coupled electron transfer (PCET) mechanism is supported by experimental rate constants, isotopic effects and theoretical calculations. The calculations revealed differences between the hydrogen abstraction reactions of phenol and indole substrates. For the latter, the calculations indicate that electron transfer and proton transfer occur as discrete steps., The authors thank the following Brazilian agencies Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) and Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ) for financial assistance. The authors also thank the Generalitat Valenciana (Prometeo Program).

Reactive oxygen species (ROS) can provoke damage to cells, where their concentrations are regulated by antioxidants. As the hydroxyl radical (&bull, OH) is the most oxidizing ROS, we have focused our attention on the use of a mechanistically based time-resolved methodology, such as laser flash photolysis, to determine the relative reactivity of alcoholic beverages towards &bull, OH as an indicator of their antioxidant potential. The selected drinks were of two different origins: (i) those derived from grapes such as red wine, white wine, white vermouth, marc and brandy and (ii) spirits not derived from grapes: triple sec, gin, whisky, and rum. Initially, we determined the quenching rate constant of ethanol with &bull, OH and then we explored the reactivity of the different beverages, which was higher than expected based on their alcoholic content. This can be attributed to the presence of antioxidants and was especially remarkable for the grape-derived drinks.

The photochemistry of the DNA biomacromolecule is an issue of paramount importance as it is part of the etiology of skin cancer development, being ultraviolet sunlight radiation the most relevant environmental carcinogen. Herein, we demonstrate the potential of pterin, an endogenous compound, to form covalent adduct under UVA irradiation with a short thymine oligomer as well as with the whole DNA polymer. Our approach is based on the spectroscopic features of pterin, which allow, by monitoring specific absorption or emission wavelengths, the following-up of the covalent binding. The results are confirmed by HPLC coupled with mass spectrometry, revealing the attachment of one or two pterin units to the homothymine 5-mer oligonucleotide. Altogether the findings point toward the role of pterin as endogenous sensitizer and genotoxic compound., The present work was partially supported by Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET-Grant PIP 112-200901-0304), Agencia de Promoción Científica y Tecnológica (ANPCyT-Grant PICT-2012–0508), Universidad Nacional de La Plata (UNLP-Grant X712). Funding from the Programa CSIC de Cooperación Científica para el Desarrollo (iCOOPLight project ref 20105CD0017) and Spanish Government (CTQ2015-70164-P) are gratefully acknowledged. S.E.R. thanks ANPCyT and CONICET for doctoral research fellowships. M.G.T thanks CONICET for postdoctoral fellowship. C.L. and A.H.T. are research members of CONICET. The authors thank Dr. Mariana Vignoni (INIFTA, CONICET) and Nathalie Martins-Froment of the Service Commun de Spectrométrie de Masse (FR2599), Université de Toulouse III (Paul Sabatier) for their crucial contributions in mass spectrometry measurements.

[EN] Through-bond triplet exciplex formation in donor-acceptor systems linked through a rigid bile acid scaffold has been demonstrated on the basis of kinetic evidence upon population of the triplet acceptors (naphthalene, or biphenyl) by through-bond triplet-triplet energy transfer from benzophenone., Financial support from the Spanish Government (Grants SEV-2012-0267, CTQ2012-38754-C03-03, CTQ2013-47872-C2-1-P and JCI-2011-09926), EU (PCIG12GA-2012-334257), Generalitat Valenciana (Prometeo Program), and Technical University of Valencia (VLC/Campus, ASIC-UPV for computational facilities and Predoctoral FPI fellowship for P. Miro) is gratefully acknowledged.

[EN] Photocatalytic degradation of three highly chlorinated contaminants, namely 2,4,6-trichlorophenol (TCP), 2,4,6-trichloroanisole (TCA) and 5-chloro-2-(2,4-dichlorophenoxy)phenol (triclosan, TCS) has been investigated in the presence of N-methylquinolinium tetrafluoroborate (NMQ(+)), a photocatalyst able to act via Type I or Type II mechanism. Photodegradation of contaminants under aerobic conditions was achieved within hours; and it was accompanied by mineralization, as demonstrated by trapping of the evolved carbon dioxide as barium carbonate. Moreover, a high degree of detoxification, based on % inmobilization of daphnids (Daphnia magna bioassay), was reached after 70 h of irradiation. Quenching of the NMQ(+) fluorescence by the pollutants was evidenced by a decrease in the emission intensity and lifetime. Detection of the reduced NMQ. by laser flash photolysis in the presence of the pollutants provided an unambigous evidence of the electron transfer process. Quenching of singlet oxygen by the contaminants showed the typical singlet oxygen quenching constants (10(5)-10(6) M-1 s(-1)). Evaluation of the relative contribution of both pathways (Type I vs Type II) point to the photodegradation occurring via a Type I mechanism, being the contribution of Type II mechanism negligible at any concentration range., Financial support from Spanish Government (Grant SEV-2016.0683 and CTQ2015-69832-C4) and generous contribution from Generalitat Valenciana (Prometeo Program) are gratefully acknowledged. We also thank support from VLC/Campus. R Martinez-Haya thanks financial support from Spanish Government (Grant SEV-2012-0267).

[EN] Heterogeneous catalysis presents significant advantages over homogeneous catalysis such as ease of separation and reuse of the catalyst. Here we show that a very inexpensive, manageable and widely available material - glass wool - can act as a catalyst support for a number of different reactions. Different metal and metal oxide nanoparticles, based on Pd, Co, Cu, Au and Ru, were deposited on glass wool and used as heterogeneous catalysts for a variety of thermal and photochemical organic reactions including reductive de-halogenation of aryl halides, reduction of nitrobenzene, Csp(3)-Csp(3) couplings, N-C heterocycloadditions (click chemistry) and Csp-Csp(2) couplings (Sonogashira couplings). The use of glass wool as a catalyst support for important organic reactions, particularly C-C couplings, opens the opportunity to develop economical heterogeneous catalysts with excellent potential for flow photo-chemistry application., This work was supported by the Natural Sciences and Engineering Research Council of Canada, the Canada Foundation for Innovation, the Canada Research Chairs Program and funding from Canada's International Development Research Centre (IDRC). Thanks are due to the RISE program for the scholarship awarded to M. C. and the Generalitat Valenciana (BEST/2017/049) for the financial support granted to M. L. M. The authors would like to thank Dr Yun Liu for helping on the acquisition of the SEM images.

In situ light initiated synthesis of silver nanoparticles (AgNP) was employed for AgNP incorporation within the polymeric matrices of medical grade polyurethane. The resulting materials showed improved antibacterial and antibiofilm activity against Pseudomonas aeruginosa with negligible toxicity for human primary skin cells and erythrocytes., The authors would like to thank Mr Michel Grenier and Mr Christopher McTiernan for their help taking some of the pictures shown in this article and for technical support in the hemolysis project. Thanks are due to Dr May Griffith for helpful discussions. Support for this work is from a Collaborative Health Research Project grant (NSERC/CIHR Canada) to JCS and T.-F.M, NSERC's CREATE program. M. L. Marin thanks the Spanish Ministerio de Educacion, Cultura y Deporte (Programa Salvador de Madariaga) and the Distinguished Visiting Researchers Program at uOttawa for their financial support. EIA thanks UOHI startup grant #1255.

Solid niobium oxide treated with phosphoric acid (NbP) was used as a heterogeneous catalyst in the protection of a series of aliphatic alcohols as tetrahydropyranyl (THP) derivatives. Protection of primary alcohols using this material with strong Brønsted acid sites was achieved in good yields (75%–94%), while moderate values were obtained in the protection of secondary and tertiary alcohols (50%–84%), largely dependent on the steric hindrance in the proximity of the hydroxyl moiety. NbP also catalyzed deprotection of THP ethers derived from primary alcohols and phenol with moderate yields (65%–99%).

[EN] Visible light photoredox catalysis is emerging as a versatile technique for a great variety of chemical transformations. Specifically,Ru(bpy)(3)(2+) has been widely used as a transition metal-based photocatalyst; however, little if any attention has been paid to the thermodynamic analysis of the photoredox processes that occur in the photocatalytic cycle of the studied reactions or, even more interestingly, to the examination of the kinetic feasibility of the involved processes. In addition, only a few studies on the progress of the reaction have been performed. Organic halides constitute a major concern for environmental remediation since they are reluctant towards aerobic oxidation. Therefore, p-halonitrobenzene (X-NB) derivatives have been selected in the present work as the model compounds to obtain a deeper understanding of their photocatalytic reduction using visible light and RuRu(bpy)(3)(2+). Thermodynamic estimations were made on the basis of the experimentally determined energy of the LUMO of RuRu(bpy)(3)(2+), which was determined to be 54.5 kcal mol(-1) from the cross-point of the normalized emission and excitation spectra, and redox potentials of X-NB and several sacrificial amines. As anticipated from chemical intuition, the feasibility of the global photoredox process increased upon going down in the group of halogens regardless of the participation of the oxidative or reductive quenching cycles. To unequivocally demonstrate the direct participation of the excited state of RuRu(bpy)(3)(2) in the photoreduction, steady-state and time-resolved experiments were carried out upon increasing X-NB or amine concentration; this allowed determining the quenching rate constants for the electron transfer processes, which were found to be in the range of 108 M-1 s(-1) for the X-NB and 106 M-1 s(-1) for the amines. Therefore, the main role of the oxidative quenching cycle has been demonstrated under the experimental conditions employed. A good correlation was found between the thermodynamic and kinetic parameters, in agreement with the expectations from Marcus theory. Upon optimization of the reaction conditions, reductive dehalogenation was found to occur leading to the parent nitrobenzene., Generous support from the Ministerio de Economia y Competitividad (Project CTQ2012-38754-C03-03 and SEV-2016-0683) and from the Generalitat Valenciana (Prometeo Program) is gratefully acknowledged.

The aim of the present work is to develop two-channel emitters to probe local hydrophobicity by means of fluorescence quenching within different biomimetic supramolecular environments. To achieve this goal, the dansyl (Dns) and tryptophan (Trp) fluorophores have been covalently attached to cholic acid (CA) in order to ensure simultaneous incorporation of the two emitting units into the same compartment. In principle, the two fluorophores of the synthesized Dns-CA-Trp probes could either exhibit an orthogonal behavior or display excited state interactions. The fluorescence spectra of 3 beta-Dns-CA-Trp showed a residual Trp emission band at ca. 350 nm and an enhanced Dns maximum in the 500-550 nm region. This reveals a partial intramolecular energy transfer, which is consistent with the Dns and Trp singlet energies. Thus, the two photoactive units are not orthogonal; nevertheless, 3 beta-Dns-CA-Trp seems appropriate as a two-channel reporter for the supramolecular systems of interest. Fluorescence quenching of 3 beta-Dns-CA-Trp by iodide (which remains essentially in bulk water) was examined within sodium cholate, sodium taurocholate, sodium deoxycholate and mixed micelles. Interestingly, a decrease in the emission intensity of the two bands was observed with increasing iodide concentrations. The most remarkable effect was observed for mixed micelles, where the quenching rate constants were one order of magnitude lower than in solution. As anticipated, the quenching efficiency by iodide decreased with increasing hydrophobicity of the microenvironment, a trend that can be correlated with the relative accessibility of the probe to the ionic quencher., Financial support from the Spanish Government (CTQ2012-38754-C03-03), Predoctoral FPU fellowship (AP2008-03295), and the Generalitat Valenciana (Prometeo Program) is gratefully acknowledged.

Correction for ‘A comprehensive mechanistic study on the visible-light photocatalytic reductive dehalogenation of haloaromatics mediated by Ru(bpy)3Cl2’ by Mireia Marin et al., Catal. Sci. Technol., 2017, 7, 4852–4858.

New photoactive dyads have been synthesized by derivatization of cholic acid (CA) or cholesterol (Ch). These compounds have proven to be efficient tools to monitor incorporation of CA and Ch to mixed micelles (MM) and to probe the microenvironment experienced inside these entities. The outstanding capability of MM to solubilize Ch has been demonstrated., We gratefully acknowledge financial support from the Generalitat Valenciana (Prometeo Program), the Spanish Government (Red RETICS de Investigacion de Reacciones Adversas a Alergenos y Farmacos (RIRAAF), Servet Contract CP11/00154 for I.A.; CTQ2009-13699 CTQ2010-14882 and Predoctoral FPU fellowship AP2008-03295 for M.G.-M.).

The second?generation Grubbs catalyst, RuCl2(H2IMes)(PCy3) (=CHPh) [GII ; H2IMes=1,3?bis(2,4,6?trimethylphenyl)?4,5?dihydroimidazol?2?ylidene, Cy=cyclohexyl], is shown to decompose during olefin metathesis to generate Ru nanoparticles (RuNPs). These RuNPs appear to contribute significantly to competing isomerization during metathesis. Larger, partially oxidized RuNPs are also observed in commercial GII , but these exhibit modest isomerization activity. Removal of RuNPs from the precatalyst does not prevent isomerization, because new, more reactive NPs are generated by catalyst decomposition during metathesis.

The aggregation behavior of bile salts is strongly dependent on the number of hydroxyl groups. Thus, cholic acid (CA), with three hydroxyls, starts forming aggregates at 15 mM, while deoxycholic, chenodeoxycholic or ursodeoxycholic acids, with two hydroxyls, start aggregating at 5-10 mM; for lithocholic acid, with only one hydroxyl group, aggregation is observed at lower concentration (2-3 mM). Here, the singular self-assembling properties of dansyl and naproxen derivatives of CA (3 beta-Dns-CA and 3 beta-NPX-CA, respectively) have been demonstrated on the basis of their photoactive properties. Thus, the emission spectra of 3 beta-Dns-CA registered at increasing concentrations (25-140 mu M) showed a remarkable non-linear enhancement in the emission intensity accompanied by a hypsochromic shift of the maximum and up to a three-fold increase in the singlet lifetime. The inflection point at around 50-70 mu M pointed to the formation of unprecedented assemblies at such low concentrations. In the case of 3 beta-NPX-CA, when the NPX relative triplet lifetime was plotted against concentration, a marked increase (up to two-fold) was observed at 40-70 mu M, indicating the formation of new 3 beta-NPX-CA assemblies at ca. 50 mu M. Additional evidence supporting the formation of new 3 beta-Dns-CA or 3 beta-NPX-CA assemblies at 40-70 mu M was obtained from singlet excited state quenching experiments using iodide. Moreover, to address the potential formation of hybrid assemblies, 1 : 1 mixtures of 3 beta-Dns-CA and 3 beta-NPX-CA (2-60 mu M, total concentration) were subjected to steady-state fluorescence experiments, and their behavior was compared to that of the pure photoactive derivatives. A lower increase in the emission was observed for 3 beta-NPX-CA in the mixture, while a huge increase was experienced by 3 beta-Dns-CA in the same concentration range (up to 60 mu M total). A partial intermolecular energy transfer from NPX to Dns, consistent with their reported singlet energies, was revealed, pointing to the formation of extremely fluorescent hybrid assemblies at 5-10 mu M (total concentration). The morphology of the entities was investigated by means of confocal microscopy. At 90 mu M, 3 beta-Dns-CA showed disperse assemblies in the mu m range., Financial support from the Spanish Government (Grants SEV-2012-0267 and CTQ2012-38754-C03-03) and the Generalitat Valenciana (Prometeo Program) is gratefully acknowledged.

The two enantiomers of the nonsteroidal antiinflammatory drug naproxen and of its methyl ester have been selected as representative probes with markedly different hydrophobicity to assess the potential of cholic acid aggregates as drug carriers by means of photophysical techniques. The different distribution of the probes between bulk solution and aggregates has been assessed by quenching of their singlet and triplet excited states by iodide and nitrite anions, respectively. This straightforward photophysical methodology can, in principle, be extended to a variety of drugs containing a photoactive chromophore. © 2012 American Chemical Society., We gratefully acknowledge financial support from the Generalitat Valenciana (GV/2009/104 and Prometeo Program 2008/090), the Spanish Government (Red RETICS de Investigacion de Reacciones Adversas a Alergenos y Farmacos (RIRAAF)), CTQ2009-13699 and Predoctoral FPU fellowship AP2008-03295 for M. G.-M.).

A new mechanism of photosensitized formation of thymine (Thy) dimers is proposed, which involves generation of a delocalized triplet excited state as the key step. This is supported by chemical evidence obtained by combining one benzophenone and two Thy units with different degrees of freedom, whereby the photoreactivity is switched from a clean Paterno-Buchi reaction to a fully chemo-, regio-, and stereoselective [2+2] cycloaddition., Financial support from the Spanish Government (Grants SEV-2012-0267, CTQ2012-38754-C03-03, and CTQ2012-32621), Generalitat Valenciana (Prometeo Program), and Technical University of Valencia (Predoctoral FPI fellowship for P.M.) is gratefully acknowledged.

[EN] Binding of natural bile acids to human serum albumin (HSA) is an important step in enterohepatic circulation and provides a measure of liver function. In this article, we report on the use of four dansyl (Dns) derivatives of cholic acid (ChA) to demonstrate a regiodifferentiation in their relative affinity for the two binding sites of HSA. Using both steady-state and time-resolved fluorescence, formation of Dns-ChA@HSA complexes was confirmed; the corresponding binding constants were determined, and their distribution between bulk solution and HSA microenvironment was estimated. By means of energy transfer from Trp to the Dns moiety, donor-acceptor distances were estimated (21-25) and found to be compatible with both site 1 and site 2 occupancies. Nevertheless, titration using warfarin and ibuprofen as specific displacement probes clearly indicated that 3¿- and 3ß-Dns-ChA bind to HSA at site 2, whereas their C-7 regioisomers bind to HSA at site 1. Furthermore, the C-3-labeled compounds are displaced by lithocholic acid, whereas they are insensitive to ChA, confirming the assumption that the former binds to HSA at site 2. Thus, Dns labeling provides a useful tool to modulate the relative affinity of ChA to the major binding sites of HSA and, in combination with other fluorescent ChA analogs, to mimic the binding behavior of natural bile acids. © 2011 American Chemical Society., Financial support from the CSIC (Fellowship I3P-2005), the Spanish Government (CTQ2009-13699, RIRAAF RETICS), and the Generalitat Valenciana (Prometeo Program) is gratefully acknowledged. Dedicated to Prof. J. V. Castell on the occasion of his 60th birthday.

Three ¿uorescent cholic acid derivatives incorporating the dansyl chromophore at positions 3R, 3ß, and 7Rhave been successfully employed to build the speciation diagram of sodium cholate by means of steady-state and time-resolved ¿uorescence., Financial support from the Spanish Government (CTQ2009-13699), Predoctoral FPU fellowship (AP2008-03295), and the Generalitat Valenciana (Prometeo Program) is gratefully acknowledged.

Interaction between bile acids and plasma proteins has attracted considerable attention over past decades. In fact, binding of bile acids to human serum albumin (HSA) determines their level in plasma, a value that can be used as a test for liver function. However, very little is known about the role that bile acids-HSA complexes play in hepatic uptake. In the present paper, we report on the utility of the singlet excited state properties of 4-nitrobenzo-2-oxa-1,3-diazole (NBD) fluorescent derivatives of cholic acid (ChA); namely, 3alpha-NBD-ChA, 3beta-NBD-ChA, 3beta-NBD-ChTau, 7alpha-NBD-ChA, and 7beta-NBD-ChA to clarify key aspects of bile acids-HSA interactions that remain poorly understood. On the basis of either absorption or emission measurements, formation of NBD-ChA@HSA complexes with 1:1 stoichiometry has been proven. Enhancement of the fluorescence emission upon addition of HSA has been used for determination of the binding constants, which are in the range of 10(4) M(-1). Energy transfer from tryptophan to NBD-ChA occurs by a FRET mechanism; the donor-acceptor distances have been determined according to Forster's theory. The estimated values (27-30 A) are compatible with both site I and site II occupancy and do not provide sufficient information for a safe assignment; however, fluorescence titration using warfarin (site I probe) and ibuprofen (site II probe) for displacement clearly indicates that the employed cholic acid derivatives bind to HSA at site I.

The photochemistry of aromatic ketones through the Norrish type I cleavage of benzoins and via photoreduction generates ketyl radicals that readily reduce many metal ions, including silver and gold. Reduction to Au(0) and Ag(0) leads to the spontaneous formation of nanoparticles (NPs) in aqueous or micellar solutions. Careful consideration of kinetic factors to minimize triplet quenching by metal ions can lead to rapid NP generation. These materials are quite stable and have interesting reactivities due to the essentially unprotected characteristics of the surface.

A comprehensive study of the ketone-photoinduced formation of gold nanoparticles (AuNPs) from gold ions in aqueous and micellar solution has been carried out. Ketones are good photosensitizers for nanoparticle synthesis not because of the energy they can absorb or deliver but rather because of the reducing free radicals they can generate; thus, efficient nanoparticle generation requires a careful selection of substrates and experimental conditions to ensure that free-radical generation occurs with high quantum efficiency and that gold ion precursors do not cause UV screening of the organic photosensitizers. A key consideration in achieving AuNP synthesis with short exposure times is minimizing excited-state quenching by gold ions; this can be achieved by temporal or spatial segregation or a combination of the two. Temporal segregation can be accomplished by using unimolecular precursors, such as benzoins, that yield ketyl radicals from triplet precursors with lifetimes of a few nanoseconds. Spatial segregation can be achieved by using self-assembled structures such as micelles. In this case, the process can be assisted by selecting ketones with n,pi* triplet states and by adding good hydrophobic hydrogen donors such as 1,4-cyclohexadiene. Systems involving bimolecular reactions of ketones are catalytic in that the ketone is recovered at the end of the reductive process. Rate constants have been determined for the quenching of excited triplets and for the scavenging of ketyl radicals by Au(I) and Au(III); in general, these values are within an order of magnitude of the rate constant for diffusion control. This article provides a paradigm for the photochemical production of nanoparticles of gold and other metal ions that highlights ten aspects that must be considered in order to design successful photochemical systems for nanoparticle generation.

Cholylamidofluorescein (CamF) has been selected as a fluorescent bile acid scaffold to perform a full characterization of its photophysical properties. In aqueous medium, under nitrogen, the absorption spectrum of CamF was expectedly dependent on pH. Under air, the presence of CO(2) resulted in a partial protonation of the photoactive form, reducing the absorbance of CamF. The fluorescence spectrum of CamF in ethanol (lambda(exc) = 481 nm) showed a broad band with maximum at 518 nm; the fluorescence quantum yield was 0.67, and the fluorescence lifetime was 4.8 ns. Laser flash photolysis of CamF showed the triplet state transient with a broad maximum at ca. 540 nm and a lifetime of 19 mu s. Flow cytometric kinetic assay of CamF uptake in real time was performed in suspensions of rat hepatocytes, showing that living hepatocytes accumulated slowly but constantly CamF along the 5-minute experimental period. Besides, intracellular fluorescence of live cells was found to be clearly dependent on the extracellular concentration of CamF. Thus, flow cytometry has allowed us to demonstrate that CamF is specifically taken up by living rat hepatocytes in a concentration-dependent fashion, suggesting the suitability of this molecule for further studies on bile-acid transport in liver cells.

The photoreactivity of the nonsteroidal anti-inflammatory 2-arylpropionic acids benoxaprofen, carprofen, naproxen, ketoprofen, tiaprofenic acid, and suprofen is reviewed with special emphasis on fundamental photophysical and photochemical properties. The absorption and emission properties of the excited states of these drugs as well as their main photodegradation routes are summarized. The photochemical mechanisms are discussed on the basis of product studies and detection of short-lived intermediates by means of laser flash photolysis. After dealing with the unimolecular processes, attention is focused on the photosensitized reactions of key biomolecules, such as lipids, proteins or nucleic acids. Finally, a short section on the photobiological effects on simple biological models is also included. Although some earlier citations are included, the literature coverage is in general limited to the last decade.

[EN] Solid niobium oxides (Nb2O5 center dot nH(2)O) and niobium phosphate were used as heterogeneous acid catalysts to promote the condensation between a switchable oxazine and a fluorescent coumarin in an aprotic solvent. The catalysts were found to promote the generation of an active methylene from the enamine-based portion of the oxazine, which was followed by a nucleophilic attack on the aldehyde functionality of the coumarin reagent. In the resulting system, the emission of the conjugated fluorophore can be observed at 670 nm and, thus, the processes occurring at the catalyst surface can be monitored in real time by total internal reflection fluorescence microscopy (TIRFM)., The authors wish to thank the Natural Sciences and Engineering Research Council (NSERC) and the Canada Research Chairs program. The University of Ottawa International Office provided grants to study niobium. Thanks are due to the Government of Canada and NSERC for a Banting Postdoctoral Fellowship to S. Impellizzeri and a Vanier Scholarship to C. Fasciani. S. Simoncelli acknowledges a DFAIT fellowship from ELAP (Emerging Leaders in the Americas Program) to support her visit to Canada. M. L. Marin thanks the financial support of the Generalitat Valenciana (BEST/2012/233) and the Distinguished Visiting Professor program of the University of Ottawa. We thank Dr. Jose-Carlos Netto-Ferreira of INMETRO (Rio de Janeiro, Brazil) for providing chemicals from CBMM.

In this work, a kinetic model, in combination with time-resolved experiments, is applied to assess the involvement of OH in the photodegradation of emerging pollutants (EPs) by means of advanced oxidation processes. In contrast with the general assumption, quenching of the short-lived OH in the real waters by the (highly diluted) EPs must be very inefficient, so removal of EPs cannot purely rely on the generation and reaction of OH. This suggests that more complex pathways have to be considered to explain the photodegradation of EPs actually achieved under the employed oxidative conditions, possibly involving other reactive species with longer lifetimes or chain degradation processes., This work was supported by the Spanish Government (Projects CTQ2012-38754-C03-03 and CTQ2012-38754-C03-02) and Technical University of Valencia (Predoctoral fellowship for J. Gomis).

Colloidal or heterogeneous nanocatalysts can improve the range and diversity of Cu(I)catalysed click reactions and facilitate catalyst separation and reuse. Catalysis by metal nanoparticles raises the question as to whether heterogeneous catalysts may cause homogeneous catalysis through metal ion leaching, since the catalytic process could be mediated by the particle, or by metal ions released from it. The question is critical as unwanted homogeneous processes could offset the benefits of heterogeneous catalysis. Here, we combine standard bench scale techniques with single-molecule spectroscopy to monitor single catalytic events in real time and demonstrate that click catalysis occurs directly at the surface of copper nanoparticles; this general approach could be implemented in other systems. We use 'from the mole to the molecule' to describe this emerging idea in which mole scale reactions can be optimized through an intimate understanding of the catalytic process at the single-molecule-single catalytic nanoparticle level., The Natural Sciences and Engineering Research Council of Canada supported this work through its Discovery and CREATE programs, while the Canadian Foundation for Innovation enabled the purchase of the instrumentation used in this work. M. L. M. thanks the Spanish Ministerio de Educacion, Cultura y Deporte (Programa Salvador de Madariaga) for its financial support.

Single molecule fluorescence microscopy techniques are used to complement conventional catalysis and high-throughput experiments in order to gain a complete picture of a model reaction. In these experiments a model nitroarene is reduced to an amine where, upon reduction, a red shift in absorption/emission, as well as an increase in emission, is observed. The reaction is studied under bulk reaction conditions by NMR spectroscopy and the fluorescence activation makes it possible to also study this reaction at the single molecule level. Fluorescence correlation spectroscopy is a valuable technique in supporting the proposed reaction mechanism and understanding the nature and duration of molecular 'visits' to catalytic sites, where both the starting material, nitroarene, and the amine product have an affinity for the catalyst., Thanks are due to the Natural Sciences and Engineering Council of Canada and the Canadian Foundation for Innovation for generous support. M. L. Marin thanks the Universitat Politecnica de Valencia (Programa de Apoyo a la Investigacion y Desarrollo) for financial support. Technical support from Roxanne Clement at uOttawa's Centre for Catalysis Research and Innovation is gratefully acknowledged.

A new efficient approach for the in situ synthesis of anchored ruthenium nanoparticles (RuNP) in three different kinds of mesoporous silica materials, MCM-41, SBA-15 and HMS, has been developed. Solids have been synthesized under very mild conditions from RuCl3 center dot H2O salt reduced in one hour at room temperature in the mesoporous silicas previously grafted with aminopropyltriethoxysilane (APTES). Well-dispersed ruthenium nanoparticles, with an average size of 3 nm, anchored into the silica network by the APTES were obtained. These materials, with a molar ratio of Si/Ru = 40, were found to be catalytically active and selective in the alcohol oxidation-Wittig olefination. Interestingly, while the reaction occurs from the alcohol, control experiments suggest that the aldehyde (the common Wittig substrate) is not involved., Thanks are due to the Natural Sciences and Engineering Council of Canada and the Canadian Foundation for Innovation for their generous support. M.L. Marin thanks the Universitat Politecnica de Valencia (Programa de Apoyo a la Investigacion y Desarrollo) for its financial support. Thanks are due to Dr. Yun Liu for advice on XPS interpretation.

[EN] The photochemical properties of itraconazole (1), a broad-spectrum antifungal agent, have been investigated in connection with reported skin photosensitivity disorders. Steady state photolysis, fluorescence and phosphorescence experiments have been performed to understand photoreactivity of 1 in biological media. The drug is unstable under UVB irradiation, suffering a primary dehalogenation of the 2,4-dichlorophenyl moiety that occurs mainly at the ortho-position. In poorly H-donating solvents, such as acetonitrile, the major photoproduct arises from intramolecular attack of the initially generated aryl radical towards the triazole ring. In addition, reduced compounds resulting from homolytic cleavage of the C-Cl bond in ortho or para positions and subsequent H-abstraction from the medium are obtained to a lesser extent. In good H-donating solvents, such as ethanol, the main photoproducts are formed by reductive dehalogenation. Furthermore, irradiation of a model dyad containing a tryptophan unit and the reactive 2,4-dichlorophenyl moiety of itraconazole leads to formation of a new covalent link between these two substructures revealing that homolysis of the C-Cl bond of 1 can result in alkylation of reactive amino acid residues of proteins, leading to formation of covalent photoadducts. Therefore, it has been established that the key process in the photosensitization by itraconazole is cleavage of the carbon-halogen bond, which leads to aryl radicals and chlorine atoms. These highly reactive species might be responsible for extensive free radical-mediated biological damage, including lipid peroxidation or photobinding to proteins., Merck Sharp & Dohme, Spanish Government (CTQ2009-13699, CTQ2012-32621, CTQ2012-38754-C03-03, RyC-2007-00476, PFIS FI09/00312), Generalitat Valenciana (Prometeo Program) and CAPES (post-doctoral fellowship of P. A. S. Programa de Pos-Graduacao em Quimica da UFRJ, Brazil) are gratefully acknowledged for financial support.

Several forms of niobium oxide were prepared, including nanostructured mesoporous materials, and their acidity properties were comprehensively investigated and compared with commercially available materials. The composites were characterized by a variety of techniques, including XRD, TEM, N-2 adsorption and Hammett acid indicator studies. The acidity of the niobium oxide derivatives was also investigated by the ability of the materials to successfully promote the halochromic ring-opening of an oxazine-coumarin probe that was specifically designed for use in fluorescence imaging studies. The ring-opening reaction was easily monitored using UV-visible, fluorescence and NMR spectroscopy. Single molecule microscopy was employed to gain a more in-depth understanding of the niobium oxide acid catalysis pathway. Using this technique, the rate of niobium oxide mediated protonation was estimated to be 1.8 x 10(-13) mol m(-2) s(-1). Single molecule analysis was also used to obtain a detailed map of Bronsted acid sites on the niobium oxide surface. The active sites, located by multiple blinking events, do not seem to be localized on any area of the material, but rather randomly distributed throughout the solid state surface. As the reaction proceeds, the sites with the highest acidity and accessibility are gradually consumed, making the next tier of acid sites available for reaction. The phenomenon was more closely characterized by using time lapsed reactivity maps., The authors wish to thank the Natural Sciences and Engineering Research Council (NSERC) and the Canada Research Chairs program. The University of Ottawa International Office provided grants to study niobium. M. L. Marin thanks the financial support of the Generalitat Valenciana (BEST/2012/233). Thanks are due to the Government of Canada and NSERC for a Banting Postdoctoral Fellowship to S. Impellizzeri and a Vanier Sholarship to C. Fasciani. S. Simoncelli acknowledges a DFAIT fellowship from ELAP (Emerging Leaders in the Americas Program) to support her visit to Canada.