Development of Fluorescent Chemosensors for Calcium and Lead Detection

This work was supported by the Associate Laboratory for Green Chemistry—LAQV which is financed by national funds from FCT-MCTES (UIDB/50006/2020 and UIDP/50006/2020). L. J. G. acknowledges FCT-MCTES for a doctoral grant (UI/BD/153617/2022). The NMR spectrometers are part of Rede Nacional de RMN (PTNMR), supported by FCT-MCTES (grant ROTEIRO/0031/2013—PINFRA/22161/2016) (co-financed by FEDER through COMPETE 2020, POCI, and PORL and FCT through PIDDAC). The X-ray infrastructure was financed by FCT-MCTES through project RECI/BBB-BEP/0124/2012. Publisher Copyright: © 2024 by the authors.In the present work, several coumarin-3-carboxamides with different azacrown ether moieties were designed and tested as potential luminescent sensors for metal ions. The derivative containing a 1-aza-15-crown-5 as a metal chelating group was found to yield the strongest response for Ca2+ and Pb2+, exhibiting an eight- and nine-fold emission increase, respectively, while other cations induced no changes in the optical properties of the chemosensor molecule. Job’s plots revealed a 1:1 binding stoichiometry, with association constants of 4.8 × 104 and 8.7 × 104 M–1, and limits of detection of 1.21 and 8.04 µM, for Ca2+ and Pb2+, respectively. Computational studies suggest the existence of a PET quenching mechanism, which is inhibited after complexation with each of these two metals. Proton NMR experiments and X-ray crystallography suggest a contribution from the carbonyl groups in the coumarin-3-carboxamide fluorophore in the coordination sphere of the metal ion.publishersversionpublishe

Synthesis of platinum (II) N-heterocyclic carbenes based on adenosine

Funding Information: This research was funded by national funds through FCT?Funda??o para a Ci?ncia e a Tecnologia, I.P., Project MOSTMICRO-ITQB (refs. UIDB/04612/2020 and UIDP/04612/2020), and IF/00109/2014/CP1244/CT0007. This work was also supported by FCT fellowships number PD/BD/135483/2018 (M.I.P.S.L.) and SFRH/BD/1444412019 (G.F.). Clara S. B. Gomes acknowledges the Associate Laboratory for Green Chemistry?LAQV and the Applied Molecular Biosciences Unit?UCIBIO, which are financed by national funds from Funda??o para a Ci?ncia e a Tecnologia (UIDB/50006/2020, UIDP/50006/2020, UIDB/04378/2020, UIDP/04378/2020, respectively).The NMR spectra were acquired at CERMAX?ITQB, integrated in the National NMR Network and are partially supported by Infrastructure Project No. 022161 (co-financed by FEDER through COMPETE 2020, POCI, PORL and FCT through PIDDAC). Mass spectroscopy measurements were obtained by the UniMass Laboratory at ITQB-NOVA, Portugal. Clara S. B. Gomes acknowledges the XTAL?Macromolecular Crystallography group for granting access to the X-ray diffractometer. X-ray infrastructure financed by FCT-MCTES through project RECI/BBB-BEP/0124/2012. Funding Information: Funding: This research was funded by national funds through FCT—Fundação para a Ciência e a Tecnologia, I.P., Project MOSTMICRO-ITQB (refs. UIDB/04612/2020 and UIDP/04612/2020), and IF/00109/2014/CP1244/CT0007. This work was also supported by FCT fellowships number PD/BD/135483/2018 (M.I.P.S.L.) and SFRH/BD/1444412019 (G.F.). Clara S. B. Gomes acknowledges the Associate Laboratory for Green Chemistry—LAQV and the Applied Molecular Biosciences Unit—UCIBIO, which are financed by national funds from Fundação para a Ciência e a Tecnologia (UIDB/50006/2020, UIDP/50006/2020, UIDB/04378/2020, UIDP/04378/2020, respectively). Funding Information: Acknowledgments: The NMR spectra were acquired at CERMAX—ITQB, integrated in the National NMR Network and are partially supported by Infrastructure Project No. 022161 (co-financed by FEDER through COMPETE 2020, POCI, PORL and FCT through PIDDAC). Mass spectroscopy measurements were obtained by the UniMass Laboratory at ITQB-NOVA, Portugal. Clara S. B. Gomes acknowledges the XTAL—Macromolecular Crystallography group for granting access to the X-ray diffractometer. X-ray infrastructure financed by FCT-MCTES through project RECI/BBB-BEP/0124/2012. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Organometallic derivatization of nucleosides is a highly promising strategy for the im-provement of the therapeutic profile of nucleosides. Herein, a methodology for the synthesis of metalated adenosine with a deprotected ribose moiety is described. Platinum (II) N-heterocyclic carbene complexes based on adenosine were synthesized, namely N-heterocyclic carbenes bearing a protected and unprotected ribose ring. Reaction of the 8-bromo-2′,3′,5′-tri-O-acetyladenosine with Pt (PPh3)4 by C8−Br oxidative addition yielded complex 1, with a PtII centre bonded to C-8 and an unprotonated N7. Complex 1 reacted at N7 with HBF4 or methyl iodide, yielding protic carbene 2 or methyl carbene 3, respectively. Deprotection of 1 to yield 4 was achieved with NH4OH. Deprotected compound 4 reacted at N7 with HCl solutions to yield protic NHC 5 or with methyl iodide yielding methyl carbene 6. Protic N-heterocyclic carbene 5 is not stable in DMSO solutions leading to the formation of compound 7, in which a bromide was replaced by chloride. The cis-influence of complexes 1–7 was examined by31P{1H} and195Pt NMR. Complexes 2, 3, 5, 6 and 7 induce a decrease of1 JPt,P of more than 300 Hz, as result of the higher cis-influence of the N-heterocyclic carbene when compared to the azolato ligand in 1 and 4.publishersversionpublishe

A Combined Single-Crystal X-ray Diffraction and Hirshfeld Analysis Approach

Publisher Copyright: © 2024 by the authors.Dimeric bismuth(III) complexes bearing bis(aryl-imino)acenaphthene (Aryl-BIAN) donor ligands of the general formulae [(Dipp-BIAN)BiCl3]2 2, [(o-iPr-BIAN)BiCl3]2 3, and [(p-iPr-BIAN)BiCl3]2 4, where Dipp = diisopropyl, o-iPr = ortho-isopropyl and p-iPr = para-isopropyl, were prepared by reaction of the corresponding neutral BIAN ligand with BiCl3, under inert atmosphere conditions. X-ray studies were performed, and their molecular structures were determined. The individual contributions of intermolecular interactions to crystal packing have been quantified by means of Hirsfeld surface analysis.publishersversionpublishe

Mechanochemistry in Portugal—A Step towards Sustainable Chemical Synthesis

LA/P/0140/2020 DL 57/2016 Norma transitória.In Portugal, publications with mechanochemical methods date back to 2009, with the report on mechanochemical strategies for the synthesis of metallopharmaceuticals. Since then, mechanochemical applications have grown in Portugal, spanning several fields, mainly crystal engineering and supramolecular chemistry, catalysis, and organic and inorganic chemistry. The area with the most increased development is the synthesis of multicomponent crystal forms, with several groups synthesizing solvates, salts, and cocrystals in which the main objective was to improve physical properties of the active pharmaceutical ingredients. Recently, non-crystalline materials, such as ionic liquids and amorphous solid dispersions, have also been studied using mechanochemical methods. An area that is in expansion is the use of mechanochemical synthesis of bioinspired metal-organic frameworks with an emphasis in antibiotic coordination frameworks. The use of mechanochemistry for catalysis and organic and inorganic synthesis has also grown due to the synthetic advantages, ease of synthesis, scalability, sustainability, and, in the majority of cases, the superior properties of the synthesized materials. It can be easily concluded that mechanochemistry is expanding in Portugal in diverse research areas.publishersversionpublishe

Click-Derived Triazoles and Triazolylidenes of Manganese for Electrocatalytic Reduction of CO2

022162, CEECIND/00509/2017, PTDC/QUI-QIN/28151/2017, RECI/BBB-BEP/0124/2012, SFRH/BD/131955/2017, UIDB/00100/2020, UIDB/04378/2020, UIDB/04612/2020, UIDP/00100/2020, UIDP/04046/2020, UIDP/04378/2020, UIDP/50006/2020, UIPD/04612/2020 Funding Information: This research was funded by FUNDA??O DE CI?NCIA E TECNOLOGIA, FCT, grant numbers: PTDC/QUI-QIN/28151/2017, SFRH/BD/131955/2017, CEECIND/00509/2017. The MOSTMICRO-ITQB was funded by UIDB/04612/2020 and UIPD/04612/2020. The NMR spectrome-ters at CERMAX were funded by 022162. LAQV and UCIBIO were funded by UIDB/50006/2020, UIDP/50006/2020, UIDB/04378/2020, and UIDP/04378/2020. The X-ray infrastructure was funded by RECI/BBB-BEP/0124/2012. The BioISI was funded by UIDB/04046/2020, UIDP/04046/2020, UIDB/00100/2020, and UIDP/00100/2020. We thank C. Almeida for elemental analysis at ITQB laboratories. Funding Information: Funding: This research was funded by FUNDAÇÃO DE CIÊNCIA E TECNOLOGIA, FCT, grant numbers: PTDC/QUI-QIN/28151/2017, SFRH/BD/131955/2017, CEECIND/00509/2017. The MOSTMICRO-ITQB was funded by UIDB/04612/2020 and UIPD/04612/2020. The NMR spectrometers at CERMAX were funded by 022162. LAQV and UCIBIO were funded by UIDB/50006/2020, UIDP/50006/2020, UIDB/04378/2020, and UIDP/04378/2020. The X-ray infrastructure was funded by RECI/BBB-BEP/0124/2012. The BioISI was funded by UIDB/04046/2020, UIDP/04046/2020, UIDB/00100/2020, and UIDP/00100/2020. Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.A series of new fac-[Mn(L)(CO)3 Br] complexes where L is a bidentate chelating ligand containing mixed mesoionic triazolylidene-pyridine (MICˆpy, 1), triazolylidene-triazole (MICˆtrz, 2), and triazole-pyridine (trzˆpy, 3) ligands have been prepared and fully characterized, including the single crystal X-ray diffraction studies of 1 and 2. The abilities of 1–3 and complex fac-[Mn(MICˆMIC)(CO)3 Br] (4) to catalyze the electroreduction of CO2 has been assessed for the first time. It was found that all complexes displayed a current increase under CO2 atmosphere, being 3 and 4 the most active complexes. Complex 3, bearing a NˆN-based ligand exhibited a good efficiency and an excellent selectivity for reducing CO2 to CO in the presence of 1.0 M of water, at low overpotential. Interestingly, complex 4 containing the strongly electron donating di-imidazolylidene ligand exhibited comparable activity to 3, when the experiments were performed in neat acetonitrile at slightly higher overpotential (−1.86 vs. −2.14 V).publishersversionpublishe

Thermal and photochemical reactions of n-pyridinebenzopyrylium multistate of species (n = 2′,3′,4′). Exploring the synthetic potentialities from the unique reactivity of position 2′

Funding Information: This work was supported by the Associate Laboratory for Green Chemistry – LAQV (projects UIDB/50006/2020 and UIDP/ 50006/2020), the Research Unit on Applied Molecular Biosciences – UCIBIO (projects UIDP/04378/2020 and UIDB/ 04378/2020) and the Associate Laboratory Institute for Health and Bioeconomy – i4HB (project LA/P/0140/2020) which are financed by national funds from FCT/MCTES. FCT/MCTES is also acknowledged for supporting the National Portuguese NMR Network (ROTEIRO/0031/2013–PINFRA/22161/2016, cofinanced by FEDER through COMPETE 2020, POCI, PORL, and FCT through PIDDAC). A. C. acknowledges financing from Fundação Calouste Gulbenkian, grant no. 219201, and from the Angolan Embassy in Lisbon, Portugal, INAGBE grant. Dr. Ramesh Pandian is acknowledged for the initial acquisition and processing of single crystal X-ray data. Publisher Copyright: © 2023 The Author(s)The kinetics and thermodynamics of the pH-dependent multistate of species generated by the trans-chalcone of n-pyridinebenzopyrylium (n = 2′, 3′) were studied by UV–vis spectroscopy, 1H NMR and HPLC-MS, and the results compared with those reported for n = 4′. Due to the slow kinetics of the multistate species interconversion, the conjugation of these techniques has shown to be a powerful tool to investigate the behaviour of these systems. The species involved in the multistate are mutatis mutandis the same observed in anthocyanins and related compounds except for the flavylium cation, which was not observed in these systems even in very acidic medium. The rates of the interconversion of the multistate species upon pH stimuli are much slower than in anthocyanins. The compound bearing the pyridine nitrogen in position 2′ gives two novel products absorbing in the visible. Formation of the new products is particularly efficient from the thermal evolution of the photochemical products obtained upon light irradiation of the protonated trans-chalcone in a mixture of methanol:acidic water (1:1). This confirms the unique capacity of the substituents in position 2′ in giving intramolecular reactions involving the benzopyrylium core. Crystal structures for the three pyridine chalcone compounds (n = 2′, 3′, 4′) were obtained and the respective structures discussed.publishersversionpublishe

Antimicrobial Activity of Manganese(I) Tricarbonyl Complexes Bearing 1,2,3-Triazole Ligands

Funding Information: We are grateful to Fundação para a Ciência e a Tecnologia, I.P., through DOI 10.54499/PTDC/QUI-QIN/0359/2021, MOSTMICRO- ITQB R&D Unit (UIDB/04612/2020 and UIDP/04612/2020) and LS4FUTURE Associated Laboratory (LA/P/0087/2020). The NMR data were acquired at CERMAX, ITQB NOVA, Oeiras, Portugal, with equipment funded by FCT, project AAC 01/SAIC/2016. Oscar A. Lenis-Rojas acknowledge national funds through FCT, POPH-Programa Operacional Potencial Humano, and FSE (European Social Fund) for the CEEC 2017 Initiative. This work was partially funded by the Department of Microbiology, Trinity College Dublin, Ireland. C. Trigueiros’ work is funded under a Provost Ph.D. Award provided by Trinity College Dublin, Dublin, Ireland. Funding of the Martins lab is also supported by Welcome Trust. This work was supported by the Associate Laboratory for Green Chemistry- LAQV, UCIBIO, and i4HB, which are financed by national funds from FCT/MCTES (UIDB/50006/2020, UIDP/50006/2020 and LA/P/0008/2020, UIDB/04378/2020 and UIDP/04378/2020, and LA/P/0140/2020, respectively). The X-ray infrastructure was financed by FCT-MCTES through project RECI/BBB-BEP/0124/2012. Publisher Copyright: © 2023 by the authors.Background. Antimicrobial resistance is one of the most pressing health issues of our time. The increase in the number of antibiotic-resistant bacteria allied to the lack of new antibiotics has contributed to the current crisis. It has been predicted that if this situation is not dealt with, we will be facing 10 million deaths due to multidrug resistant infections per year by 2050, surpassing cancer-related deaths. This alarming scenario has refocused attention into researching alternative drugs to treat multidrug-resistant infections. Aims. In this study, the antimicrobial activities of four manganese complexes containing 1,2,3,-triazole and clotrimazole ligands have been evaluated. It is known that azole antibiotics coordinated to manganese tricarbonyl complexes display interesting antimicrobial activities against several microbes. In this work, the effect of the introduction of 1,2,3,-triazole-derived ligands in the [Mn(CO)3(clotrimazole)] fragment has been investigated against one Gram-positive bacterium and five Gram-negative bacteria. Methods. The initial antimicrobial activity of the above-mentioned complexes was assessed by determining the minimum inhibitory and bactericidal concentrations using the broth microdilution method. Growth curves in the presence and absence of the complexes were performed to determine the effects of these complexes on the growth of the selected bacteria. A possible impact on cellular viability was determined by conducting the MTS assay on human monocytes. Results. Three of the Mn complexes investigated (4–6) had good antimicrobial activities against all the bacteria tested, with values ranging from 1.79 to 61.95 µM with minimal toxicity. Conclusions. Due to the increased problem of antibiotic resistance and a lack of new antibacterial drugs with no toxicity, these results are exciting and show that these types of complexes can be an avenue to pursue in the future.publishersversionpublishe

A model compound for pyridinechalcone-based multistate systems. Ring opening-closure as the slowest kinetic step of the multistate

UID/QUI/50006/2019. PTDC/QEQ-QFI/1971/2014. PTDC/QUI-COL/32351/2017. PTDC/QUI-QFI/30951/2017. grant no. 219201.Anthocyanins and related flavylium derivatives exist in aqueous solution as a pH-dependent mole fraction distribution of species (a multistate system) with known biological activity. Introduction of nitrogen heterocycles in the flavylium core can lead to multistates with different constitution and increased activity. Compound 1, a diethylamino derivative of 4-pyridinechalcone, was synthesized and characterized by X-ray crystallography, showing a pH-dependent reaction network similar to anthocyanins and related compounds. The several species present at the equilibrium multistate were fully characterized by 1H NMR and 13C NMR. The thermodynamics and kinetics of the multistate were studied through pH jumps followed by 1H NMR and UV-vis absorption including stopped-flow for the faster kinetic steps. In the parent 4-pyridinechalcone compound, protonation of the pyridine nitrogen for pH 4 prevents formation of the flavylium cation. In compound 1, the first protonation takes place in the diethylamino substituent and in acidic medium, two new flavylium derivatives, a single (2 pH 4) and a double (pH 1) positively charged species, in equilibrium with protonated hemiketal, cis and trans chalcones, have been characterized. Differently from anthocyanins and related compounds, experimental evidence for an unexpected very slow (0.0003 s-1) ring opening-closure between the hemiketal and the cis-chalcone (tautomerization) was achieved.publishe

First examples of neutral and cationic indenyl nickel(II) complexes bearing arsine or stibine ligands: highly active catalysts for the oligomerisation of styrene

New indenyl nickel(II) complexes bearing arsine or stibine ligands synthesised by a new methodology exhibit very high catalytic activities for the oligomerisation of styrene