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Giamello E, Theobald F, Naccache C, Vedrine JC. Étude par RPE des molybdates de bismuth supportés sur silice. ACTA ACUST UNITED AC 2017. [DOI: 10.1051/jcp/1978750305] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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27
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Moreno-González M, Palomares AE, Chiesa M, Boronat M, Giamello E, Blasco T. Evidence of a Cu2+–Alkane Interaction in Cu-Zeolite Catalysts Crucial for the Selective Catalytic Reduction of NOx with Hydrocarbons. ACS Catal 2017. [DOI: 10.1021/acscatal.6b03473] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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García‐López EI, Marcì G, Pomilla FR, Liotta LF, Megna B, Paganini MC, Gionco C, Giamello E, Palmisano L. Improved (Photo)catalytic Propene Hydration in a Gas/Solid System by Using Heteropolyacid/Oxide Composites: Electron Paramagnetic Resonance, Acidity, and Role of Water. Eur J Inorg Chem 2017. [DOI: 10.1002/ejic.201601396] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Chiesa M, Livraghi S, Giamello E, Albanese E, Pacchioni G. Ferromagnetic Interactions in Highly Stable, Partially Reduced TiO 2 : The S=2 State in Anatase. Angew Chem Int Ed Engl 2017; 56:2604-2607. [PMID: 28128485 DOI: 10.1002/anie.201610973] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Indexed: 11/07/2022]
Abstract
We report direct evidence for quintuplet spin states in a particular kind of reduced TiO2 anatase obtained by the mild oxidation of TiB2 under hydrothermal conditions. Continuous-wave and pulse EPR spectroscopy at X and Q band frequencies provide compelling evidence for the presence of S=2 states, stable in a wide range of temperatures up to room temperature. A tentative model, corroborated by spin-polarized DFT calculations, is proposed, which consists of four ferromagnetically interacting Ti3+ ions with distances ranging from 0.5 nm to 0.8 nm and tetrahedral arrangement.
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Chiesa M, Livraghi S, Giamello E, Albanese E, Pacchioni G. Ferromagnetic Interactions in Highly Stable, Partially Reduced TiO2
: The S=
2 State in Anatase. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201610973] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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31
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Baravalle R, Valetti F, Catucci G, Gambarotta G, Chiesa M, Maurelli S, Giamello E, Barone I, Catalano S, Andò S, Di Nardo G, Gilardi G. Effect of sildenafil on human aromatase activity: From in vitro structural analysis to catalysis and inhibition in cells. J Steroid Biochem Mol Biol 2017; 165:438-447. [PMID: 27616271 DOI: 10.1016/j.jsbmb.2016.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 09/05/2016] [Accepted: 09/06/2016] [Indexed: 11/15/2022]
Abstract
Aromatase catalyses the conversion of androgens into estrogens and is a well-known target for breast cancer therapy. As it has been suggested that its activity is affected by inhibitors of phosphodiesterase-5, this work investigates the potential interaction of sildenafil with aromatase. This is carried out both at molecular level through structural and kinetics assays applied to the purified enzyme, and at cellular level using neuronal and breast cancer cell lines. Sildenafil is found to bind to aromatase with a KD of 0.58±0.05μM acting as a partial and mixed inhibitor with a maximal inhibition of 35±2%. Hyperfine sublevel correlation spectroscopy and docking studies show that sildenafil binds to the heme iron via its 6th axial water ligand. These results also provide information on the starting molecular scaffold for the development of new generations of drugs designed to inhibit aromatase as well as phosphodiesterase-5, a new emerging target for breast cancer therapy.
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Panarelli EG, Livraghi S, Maurelli S, Polliotto V, Chiesa M, Giamello E. Role of surface water molecules in stabilizing trapped hole centres in titanium dioxide (anatase) as monitored by electron paramagnetic resonance. J Photochem Photobiol A Chem 2016. [DOI: 10.1016/j.jphotochem.2016.02.015] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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33
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Morra S, Maurelli S, Chiesa M, Mulder DW, Ratzloff MW, Giamello E, King PW, Gilardi G, Valetti F. The effect of a C298D mutation in CaHydA [FeFe]-hydrogenase: Insights into the protein-metal cluster interaction by EPR and FTIR spectroscopic investigation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2015; 1857:98-106. [PMID: 26482707 DOI: 10.1016/j.bbabio.2015.10.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2015] [Revised: 10/01/2015] [Accepted: 10/15/2015] [Indexed: 01/17/2023]
Abstract
A conserved cysteine located in the signature motif of the catalytic center (H-cluster) of [FeFe]-hydrogenases functions in proton transfer. This residue corresponds to C298 in Clostridium acetobutylicum CaHydA. Despite the chemical and structural difference, the mutant C298D retains fast catalytic activity, while replacement with any other amino acid causes significant activity loss. Given the proximity of C298 to the H-cluster, the effect of the C298D mutation on the catalytic center was studied by continuous wave (CW) and pulse electron paramagnetic resonance (EPR) and by Fourier transform infrared (FTIR) spectroscopies. Comparison of the C298D mutant with the wild type CaHydA by CW and pulse EPR showed that the electronic structure of the center is not altered. FTIR spectroscopy confirmed that absorption peak values observed in the mutant are virtually identical to those observed in the wild type, indicating that the H-cluster is not generally affected by the mutation. Significant differences were observed only in the inhibited state Hox-CO: the vibrational modes assigned to the COexo and Fed-CO in this state are shifted to lower values in C298D, suggesting different interaction of these ligands with the protein moiety when C298 is changed to D298. More relevant to the catalytic cycle, the redox equilibrium between the Hox and Hred states is modified by the mutation, causing a prevalence of the oxidized state. This work highlights how the interactions between the protein environment and the H-cluster, a dynamic closely interconnected system, can be engineered and studied in the perspective of designing bio-inspired catalysts and mimics.
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Chen HYT, Livraghi S, Giamello E, Pacchioni G. Mechanism of the Cyclo-Oligomerisation of C2H2on Anatase TiO2(101) and (001) Surfaces and Their Reduction: An Electron Paramagnetic Resonance and Density Functional Theory Study. Chempluschem 2015; 81:64-72. [DOI: 10.1002/cplu.201500383] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Indexed: 11/10/2022]
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Morra E, Maurelli S, Chiesa M, Giamello E. Rational Design of Engineered Multifunctional Heterogeneous Catalysts. The Role of Advanced EPR Techniques. Top Catal 2015. [DOI: 10.1007/s11244-015-0418-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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36
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Morra E, Giamello E, Van Doorslaer S, Antinucci G, D'Amore M, Busico V, Chiesa M. Probing the Coordinative Unsaturation and Local Environment of Ti3+ Sites in an Activated High-Yield Ziegler-Natta Catalyst. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201412052] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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37
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Morra E, Giamello E, Van Doorslaer S, Antinucci G, D'Amore M, Busico V, Chiesa M. Probing the Coordinative Unsaturation and Local Environment of Ti3+ Sites in an Activated High-Yield Ziegler-Natta Catalyst. Angew Chem Int Ed Engl 2015; 54:4857-60. [DOI: 10.1002/anie.201412052] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 01/30/2015] [Indexed: 11/12/2022]
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Biedrzycki JJ, Livraghi S, Corazzari I, Mino L, Spoto G, Giamello E. On the redox mechanism operating along C2H2 self-assembly at the surface of TiO2. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:569-577. [PMID: 25514364 DOI: 10.1021/la504290d] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The interaction of acetylene with the TiO2 surface at room temperature entails a complex set of self-assembly reactions with the formation of products having relatively high molecular weight. In a previous paper by some of us (Jain, S. M.; et al. J. Mater. Chem. A 2014, 2, 12247-12254), the C2H2-TiO2 reaction has been monitored, essentially by Fourier transform infrared spectroscopy, at the surface of P25 (a mixture of anatase and rutile, typical benchmark material in the field of photocatalysis) in order to elucidate the nature of the products of this surface reaction. In the present paper, the same process was followed, for the first time, using electron paramagnetic resonance (EPR) and monitoring by the thermogravimetric analysis the weight loss of the material upon heating in order to further investigate the complex mechanism of the surface reaction. This was done using pure anatase and comparing the EPR results with those concerning both rutile and P25. The self-assembly mechanism occurring at the interface is accompanied by the formation of EPR visible Ti(3+) centers due to electrons injection in the TiO2 substrate. This finding clarifies that at least one of the reaction channels of this complex process (namely, the formation of polycyclic aromatic hydrocarbons) is based on the heterolytic dissociative chemisorption of acetylene, followed by a redox interaction between the adsorbate and the solid, which allows the creation of the building blocks necessary to assemble polyaromatic molecules.
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Morra E, Giamello E, Chiesa M. Probing the redox chemistry of titanium silicalite-1: formation of tetrahedral Ti3+ centers by reaction with triethylaluminum. Chemistry 2014; 20:7381-8. [PMID: 24824439 DOI: 10.1002/chem.201304139] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Revised: 11/21/2013] [Indexed: 11/10/2022]
Abstract
Transition-metal ions with open-shell configurations hold promise in the development of novel coordination chemistry and potentially unprecedented redox catalysis. Framework-substituted Ti(3+) ions with tetrahedral coordination are generated by reductive activation of titanium silicalite-1 with triethylaluminum, an indispensable co-catalyst for heterogeneous Ziegler-Natta polymerization catalysts. Continuous-wave and pulse electron paramagnetic resonance methods are applied to unravel details on the local environment of the reduced transition metal-ions, which are shown to be part of the silica framework by detection of (29)Si hyperfine interactions. The chemical accessibility of the reduced sites is probed using ammonia as probe molecule. Evidence is found for the coordination of a single ammonia molecule. Comparison to similar systems, such as TiAlPO-5, reveals clear differences in the coordination chemistry of the reduced Ti sites in the two solids, which may be understood considering the different electronic properties of the solid frameworks.
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Gionco C, Paganini MC, Giamello E, Burgess R, Di Valentin C, Pacchioni G. Cerium-Doped Zirconium Dioxide, a Visible-Light-Sensitive Photoactive Material of Third Generation. J Phys Chem Lett 2014; 5:447-451. [PMID: 26276590 DOI: 10.1021/jz402731s] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The dispersion of small amounts of Ce(4+) ions in the bulk of ZrO2 leads to a photoactive material sensitive to visible light. This is shown by monitoring with EPR the formation and the reactivity of photogenerated (λ > 420 nm) charge carriers. The effect, as confirmed by DFT calculations, is due to the presence in the solid of empty 4f Ce states at the mid gap, which act as intermediate levels in a double excitation mechanism. This solid can be considered an example of a third-generation photoactive material.
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Gionco C, Giamello E, Mino L, Paganini MC. The interaction of oxygen with the surface of CeO2–TiO2 mixed systems: an example of fully reversible surface-to-molecule electron transfer. Phys Chem Chem Phys 2014; 16:21438-45. [DOI: 10.1039/c4cp03195d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
CeO2–TiO2 mixed oxides showed an unusual and fully reversible interaction with molecular oxygen similar to that of natural and synthetic oxygen carriers.
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Gionco C, Battiato A, Vittone E, Paganini MC, Giamello E. Structural and spectroscopic properties of high temperature prepared ZrO2–TiO2 mixed oxides. J SOLID STATE CHEM 2013. [DOI: 10.1016/j.jssc.2013.02.040] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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43
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Chiesa M, Paganini MC, Livraghi S, Giamello E. Charge trapping in TiO2 polymorphs as seen by Electron Paramagnetic Resonance spectroscopy. Phys Chem Chem Phys 2013; 15:9435-47. [DOI: 10.1039/c3cp50658d] [Citation(s) in RCA: 163] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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Maurelli S, Chiesa M, Giamello E, Leithall RM, Raja R. A HYSCORE investigation of bimetallic titanium–vanadium microporous catalysts: elucidating the nature of the active sites. Chem Commun (Camb) 2012; 48:8700-2. [DOI: 10.1039/c2cc33997h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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45
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Corazzari I, Livraghi S, Ferrero S, Giamello E, Fubini B, Fenoglio I. Inactivation of TiO2 nano-powders for the preparation of photo-stable sunscreens via carbon-based surface modification. ACTA ACUST UNITED AC 2012. [DOI: 10.1039/c2jm32876c] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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Livraghi S, Maurelli S, Paganini MC, Chiesa M, Giamello E. Probing the Local Environment of Ti3+ Ions in TiO2 (Rutile) by 17O HYSCORE. Angew Chem Int Ed Engl 2011. [DOI: 10.1002/ange.201100531] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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47
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Livraghi S, Maurelli S, Paganini MC, Chiesa M, Giamello E. Probing the Local Environment of Ti3+ Ions in TiO2 (Rutile) by 17O HYSCORE. Angew Chem Int Ed Engl 2011; 50:8038-40. [DOI: 10.1002/anie.201100531] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Indexed: 11/11/2022]
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48
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Maurelli S, Livraghi S, Chiesa M, Giamello E, Van Doorslaer S, Di Valentin C, Pacchioni G. Hydration Structure of the Ti(III) Cation as Revealed by Pulse EPR and DFT Studies: New Insights into a Textbook Case. Inorg Chem 2011; 50:2385-94. [DOI: 10.1021/ic1021802] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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49
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Dozzi MV, Livraghi S, Giamello E, Selli E. Photocatalytic activity of S- and F-doped TiO2in formic acid mineralization. Photochem Photobiol Sci 2011; 10:343-9. [DOI: 10.1039/c0pp00182a] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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50
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Czoska AM, Livraghi S, Paganini MC, Giamello E, Di Valentin C, Pacchioni G. The nitrogen–boron paramagnetic center in visible light sensitized N–B co-doped TiO2. Experimental and theoretical characterization. Phys Chem Chem Phys 2011; 13:136-43. [DOI: 10.1039/c0cp00143k] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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