CV
Flavio Maran
Flavio Maran obtained his Laurea Degree in Chemistry, Magna cum Laude, from the
University of Padova in 1980. He took a faculty position in the same university in 1983. He
is currently Professor of Physical Chemistry at the University of Padova where he leads
the Electrochemistry Group and teaches physical chemistry, advanced physical chemistry,
molecular electrochemistry, and electron transfer reactions to undergraduate and graduate
chemistry and biotechnology students.
He has been a Visiting Scientist in Canada, USA, and Japan. Chairman of ECHEMS, the
new organization for the development and support of electrochemical activities in
emerging areas of research. Member of national and international chemical societies.
Member of the Stirring Committee of the PhD School of Molecular Sciences of the
University of Padova. Member of committees of the Electrochemical Society. Referee for
many Peer Review International Journals and Reviewer of Research Projects for
European and North-American Foundations. Organizer of scientific meetings and many
international symposia on electrochemistry and electron transfer.
Sabrina Antonello
Sabrina Antonello was born in Italy in 1970. She was educated at the University of
Padova, where she received her Laurea degree in Chemistry in 1996. She obtained her
PhD in Chemistry in 2000 with a Thesis entitled "Dissociative Electron Transfers", which
was awarded in 2001 as the best PhD thesis by the Electrochemistry Division of the Italian
Chemical Society. She currently holds a Research Associate Fellowship at the University
of Padova. Her research interests include electron transfer across interfaces and
electrochemical microscopy techniques.
The Maran group is currently involved in collaborations with various research groups in
Italy (e.g., Claudio Toniolo, Vincenzo Barone, University of Naples; ), Canada, USA,
Japan, Denmark, and Spain.
Research Interests
The Maran group at the University of Padova carries out research in intramolecular
dissociative electron-transfer reactions, electron-transfer reactions through biologically
relevant bridges, charge-transfer processes across interfaces, and gold nanoclusters
protected by peptide monolayers.
Intramolecular dissociative electron transfer
Predicting the rate of electron transfer (ET) reactions is one of the most significant and
fascinating achievements of modern physical chemistry. Thanks to the Marcus theory of
ET and subsequent refinements, the ET rates can be estimated using rather simple
concepts, such as reaction driving force, reorganization energy, and electronic coupling
between reactant and product states. In several chemical systems, the ET causes the
cleavage of a  bond, therefore leading to a dissociative ET (DET). Generally speaking,
DETs are useful reactions in that they provide an elegant and chemically clean way to
generate reactive species such as radicals and, depending on the fact that we deal with a
reductive or oxidative process, bases or acids, and nucleophiles or electrophiles. At
present, we have reached a valuable understanding of how the rate of heterogeneous and
intermolecular DETs changes as a function of the reaction free energy. On the other hand,
much less is known for intramolecular DETs. One of the purposes of our research is to
assess to which extent the knowledge so far accumulated can be extended to
intramolecular DETs. To address this problem, we are currently studying the activation and
intramolecular DET in specifically devised donor-spacer-acceptor molecules, mostly using
electrochemical techniques; to better understand the dynamics of these reactions, specific
theoretical calculations are also carried out.
Electron-transfer reactions through biologically relevant bridges
Understanding how electrons are transferred in proteins is a challenging task requiring
knowledge of many related aspects, such as the properties of the donor (D) and the
acceptor (A), the effect of the surrounding medium, and the electronic coupling between
the relevant states involved in the process. To study how fine details or specific aspects
may tune electron transfer (ET) reactions in such complex environments and taking into
account that the peptide chains are essential in assisting long-range ET in proteins,
focusing on well defined D-peptide-A model molecules is a successful strategy adopted by
several research groups. It has been proposed that long range ET through biological
systems may occur by both the superexchange mechanism, a coherent tunneling
mechanism in which ET between D and A occurs without transient occupation of the states
of the bridge, and the electron hopping mechanism, where electron migration takes place
by using electronic states that are localized onto the units forming the bridge itself. It is still
unclear, however, whether this scheme is actually applicable to peptides and proteins. Our
research is aimed at understanding this important issue, which rules the efficiency of longrange ET. We use electrochemical methods and quantum mechanical (QM) calculations to
gain insights into this problem and to rationalize the physico-chemical effects modulating
the rate of intramolecular ET in donor-peptide-acceptor systems in which the length of the
oligopeptide spacer is varied and the nature of D and A changed. To investigate
systematically how distance increase impact the electron tunneling, we are focusing on
series of peptides having well-defined conformational preferences. These peptides are
homo-oligomers based on the -aminoisobutyric acid (Aib) residue and are known for their
propensity to form rigid 310-helices because of steric hindrance at the -carbon and the
resulting restricted torsional freedom.
Charge-transfer processes across interfaces
Nature provides a variety of systems in which molecules self-assemble to form ordered
sequences that are kept together by noncovalent forces. Membranes and self-assembled
monolayers are particularly important examples of these systems. Charge transfer
processes occurring at the interface between two immiscibile electrolyte solutions, or
between solutions separated by a cellular membrane, or though self-assembled
monolayers are issues of current active research. In particular, many studies have been
directed to understand the role and mechanisms by which membrane-active peptides form
channels. To study the mechanisms by which peptides act, different model membranes
can be employed, such as solid-supported membranes and bilayer lipid membranes. Part
of this project is to modify the interface or membrane by using suitably devised and wellcharacterized peptide systems capable of providing a better electrical connection between
the two phases or, more generally, though the interphase. The goal eventually is to control
the charge transfer between the two phases by understanding the mechanism of the
transfer across the interface and the role of peptides generating charge-transfer channels.
The above biomimetic membranes allow for the application of various powerful surface
techniques, such as electrochemical methods and scanning probe microscopies. We will
employ electrochemical techniques and scanning probe methods. In this connection,
particular emphasis will be given to the use of the scanning electrochemical microscope
(SECM), an instrument devised to study chemical and physical processes at high
resolution near interfaces, and of the atomic force microscopy (AFM), which provides an
exceptionally powerful and versatile tool to study the packing of self-assembled layers. We
also will anchor peptides to metal electrodes by means of metal-sulfur bonds. The
peptides forming the ensuing self-assembled monolayer will be composed by both noncoded and coded alpha-amino acids. This part of the project concerns the effects of the
peptide length and secondary structure on the ET rate between the electrode and selected
acceptor (or donor) species on the solution side of the self-assembled monolayer system.
Peptide protected gold nanoclusters
Controlling the electronic properties of nanometer-scale materials is one of the hottest
areas of current research. In particular, several research groups are strongly focusing on
the detailed understanding of the physical and chemical properties of monolayer-protected
gold clusters (MPCs), which are relatively easy to fabricate and display high stability. The
monolayer not only protects the core from particle aggregation but also furnishes a way to
control the electrical, optical, magnetic, and chemical properties of the MPC itself. In
addition, the ligands provide a scaffold to attach molecular groups carrying out specific
functions, an issue of paramount relevance for the use of these systems in the area of
devices, sensors, and for biomedical applications. Our group is interested in synthesizing
and characterizing gold clusters protected by peptides decorated with groups displaying
specific physico-chemical properties. Although the project has a fundamental character,
the materials will be also chosen by keeping an eye on possible applications. A key aspect
of this project is the use of thiolized peptides based on the alpha-aminoisobutiric acid (Aib)
unit: even when short, the Aib oligopeptides form a rather robust secondary structure (3 10helix). We wish to study i) the factors controlling the electronic communication with the
gold core through the peptide monolayer; ii) the electrochemistry and photophysics of the
so-devised particles; iiii) the possibility of obtaining complex structures in which the various
MPCs are chemically connected in 1, 2, and 3D architectures.
Recent Selected Publications
1. "Intramolecular Dissociative Electron Transfer" Antonello, S.; Maran, F. Chem. Soc.
Rev. 2005, In press. Reprint
2. "Evidence against the Hopping Mechanism as an Important Electron Transfer Pathway
for Conformationally Constrained Oligopetides" Polo, F.; Antonello, S.; Formaggio, F.;
Toniolo, C.; Maran, F. J. Am. Chem. Soc. 2005, 127, 492-493. Reprint
3. "Understanding Electron Transfer Across Negatively-Charged Aib Oligo-Peptides"
Barone, V.; Antonello, S.; Formaggio, F.; Improta, R.; Maran, F. J. Phys. Chem. B 2005,
109, 1023-1033. Reprint
4. "ElectronTransfer to Sulfides: Heterogeneous Kinetics, C-S Bond Cleavage, and Selfprotonation" Meneses, A. B.; Antonello, S.; Arévalo, M.-C.; Maran, F. Electrochim. Acta
2005, 50, 1207-1215. Reprint
5. "Synthesis and Characterization of a Series of Homopeptide Peroxyesters" Formaggio,
F.; Crisma, M.; Scipionato, L.; Antonello, S.; Maran, F.; Toniolo, C. Org. Lett. 2004, 6,
2753-2756. Reprint
6. "Formation and Cleavage of Aromatic Disulfide Radical Anions" Antonello, S.;
Daasbjerg, K.; Jensen, H.; Taddei, F.; Maran, F. J. Am. Chem. Soc. 2003, 125, 1490514916. Reprint
7. "Anomalous Distance Dependence of Electron Transfer Across Peptide Bridges"
Antonello, S.; Formaggio, F.; Moretto, A.; Toniolo, C.; Maran, F. J. Am. Chem. Soc. 2003,
125, 2874-2875. Reprint
8. "Insights into the Free Energy Dependence of Intramolecular Dissociative Electron
Transfers" Antonello, S.; Crisma, M.; Formaggio, F.; Moretto, A.; Taddei, F.; Toniolo, C.;
Maran, F. J. Am. Chem. Soc. 2002, 124, 11503-11513. Reprint
9. "Theoretical and Electrochemical Investigation on Dissociative Electron Transfers
Proceeding Through the Formation of Loose Radical Anions: Reduction of Symmetrical
and Unsymmetrical Disulfides" Antonello, S.; Benassi, R.; Gavioli, G.; Taddei, F; Maran, F.
J. Am. Chem. Soc. 2002, 124, 7529-7538. Reprint
10. "Dissociative Electron Transfer" Maran, F.; Workentin, M. S. Interface 2002, 11, 44-49.
Reprint
11. "Serendipitous Discovery of Peptide Dialkyl Peroxides" Moretto, A.; De Zotti, M.;
Scipionato L.; Formaggio, F.; Crisma, M.; Toniolo, C.; Antonello, S.; Maran, F.;
Broxterman, Q. B. Helv. Chim. Acta 2002, 85, 3099-3112. Reprint
12. "Nitroxyl Peptides as Catalysts of Enantioselective Oxidations" Formaggio, F.;
Bonchio, M.; Crisma, M.; Peggion, C.; Mezzato, S.; Polese, A.; Barazza, A.; Antonello, S.;
Maran, F.; Broxterman, Q. B.; Kaptein, B.; Kamphuis, J.; Vitale, R. M.; Saviano, M.;
Benedetti, E.; Toniolo, C. Chem. Eur. J. 2002, 8, 84-93. Reprint
13. "Intramolecular, Intermolecular, and Heterogeneous Nonadiabatic Dissociative
Electron Transfer to Peresters" Antonello, S.; Formaggio, F.; Moretto, A.; Toniolo, C.;
Maran, F. J. Am. Chem. Soc. 2001, 123, 9577-9584. Reprint
14. "Kinetics and Mechanisms of the Dissociative Reduction of C-X and X-X Bonds (X = O,
S)" Maran, F.; Wayner, D. D. M.; Workentin, M. S. Adv. Phys. Org. Chem. 2001, 36, p. 85166. Reprint
15. "Nickel(I)(salen)-Electrocatalyzed Reduction of Benzyl Chlorides in the Presence of
Carbon Dioxide" Gennaro, A.; Isse, A. A.; Maran, F. J. Electroanal. Chem. 2001, 507, 124134. Reprint
16. "Reactivity of [Pd3(-OAc)3(,2-MeSCHCO2Et-C,S)3] in the Presence of
Triphenylphosphine: A Model of the Early Steps of the Pd/PR 3 Catalyzed Heck Reaction"
Basato, M.; Sesto, B.; Zecca, M.; Valle, G.; Antonello, S.; Maran, F. J. Organomet. Chem.
2000, 601, 201-210. Reprint
17. "The Role and Relevance of the Transfer Coefficient  in the Study of Dissociative
Electron Transfers. Concepts and Examples from the Electroreduction of Perbenzoates"
Antonello, S.; Maran, F. J. Am. Chem. Soc. 1999, 121, 9668-9676. Reprint
18. "Kinetics and Temperature Dependence of the Reduction of Dialkyl Peroxides. New
Insights into the Dynamics of Dissociative Electron Transfer" Donkers, R. L.; Maran, F.;
Wayner, D. D. M.; Workentin, M. S. J. Am. Chem. Soc. 1999, 121, 7239-7248. Reprint
19. "Evidence for Large Inner Reorganization Energies in the Reduction of Diaryl
Disulfides: Toward a Mechanistic Link between Concerted and Stepwise Dissociative
Electron Transfers?" Daasbjerg, K.; Jensen, H.; Benassi, R.; Taddei, F.; Antonello, S.;
Gennaro, A.; Maran, F. J. Am. Chem. Soc. 1999, 121, 1750-1751. Reprint
20. "Mechanism of the Dissociative Electrooxidation of Oxalate in Aprotic Solvents" Isse,
A. A.; Gennaro, A.; Maran, F. Acta Chem. Scand. 1999, 53, 1013-1022. Reprint
Collaborazioni scientifiche
Sono in atto varie collaborazioni scientifiche nazionali ed internazionali. Quelle
internazionali sono coi gruppi dei seguenti ricercatori:
Prof. M. S. Workentin, University of Western Ontario (London, Ontario, Canada)
Prof. M.-C. Arévalo, Universidad de La Laguna (La Laguna, Spagna)
Prof. K. Daasbjerg, Aarhus University (Aarhus, Danimarca)
Prof. J. Lessard, Université de Sherbrooke (Sherbrooke, Quebec, Canada)
Prof. J. Yoshida, Kyoto University (Kyoto, Giappone)
Quelle nazionali sono, in particolare, con:
Prof. F. Taddei, Università di Modena e Reggio Emilia
Prof. V. Barone, Università di Napoli "Federico II"
Prof. C. Toniolo, Università di Padova
Prof. Maria Anita Rampi, Università di Ferrara
Prof. Rolando Guidelli, Università di Firenze
Altre attività professionali
Componente di vari organi collegiali o professionali, sia in Italia che all'estero, e di varie
iniziative scientifiche, tra cui:
- Collegio Docenti della Scuola di Dottorato in Scienze Chimiche, Università di Padova;
- Società Chimica Italiana (SCI), Electrochemical Society (ECS), International Society of
Electrochemistry (ISE);
- Comitato direttivo della Division of Organic and Biological Electrochemistry (O&BE),
ECS;
- Chairman dell'International Working Group on the International Promotion of Organic
Electrochemistry (O&BE Division, ECS);
- Chairman dell'ECHEMS, gruppo internazionale di lavoro per la promozione e lo studio
delle possibilità offerte dall'elettrochimica nell'ambito di settori caldi della ricerca
contemporanea;
- Comitato New Materials and Nanotechnologies (ECS).
- Comitato per la valuazione di candidati a Habilitation à Diriger des Recherches
(Francia);
- Commissario esterno per la PhD School of Chemistry, The Univeristy of Western
Ontario (London, Ontario, Canada);
- Rappresentante per l'Elettrochimica Organica dell'Italian-German Workshop of
Electrochemistry;
- Comitato di valutazione delle candidature per il Baizer Award (massimo
riconoscimento mondiale nell'ambito dell'elettrochimica organica);
- Referee per numerose riviste scientifiche internazionali;
- Revisore di progetti di ricerca del National Science Foundation (USA), Natural
Sciences and Engineering Research Council of Canada (Canada), INTAS (UE), Alban
(UE).
- Co-editore di: Organic Electrochemistry - Manuel M. Baizer Award (Fifth International
Symposium), The Electrochemical Society Volume Series: Pennington, NJ, 2002-10.
- Organizzatore o Chairman dei seguenti Simposi internazionali o Congressi:
Simposio 5th Manuel M. Baizer Award Symposium on Organic Electrochemistry, 201st ECS Meeting,
Philadelphia (Pennsylvania-USA), 12-17 maggio 2002.
Simposio Electron Transfer Through Organic and Biological Bridges, 203rd ECS Meeting, Parigi
(Francia), 27 aprile - 2 maggio 2003.
Simposio Electrochemistry Symposium in Honor of Michael Weaver, 204th ECS Meeting, Orlando
(Florida-USA), 12-17 ottobre 2003.
Simposio Electron Transfer Through Organic and Biological Bridges II, 207th ECS
Meeting, Quebec City (Quebec-Canada), 15 - 20 maggio 2005;
Congresso Giornate dell'Elettrochimica Italiana GEI 2004, Padova, 5-9 settembre
2004.
1st ECHEMS Meeting, Venezia, 30 giugno - 3 luglio 2005.