Tunneling is a quantum mechanical phenomenon that describes how particles permeate through potential energy barriers. The occurrence of tunneling in chemical reactions has been largely ignored by the organic chemistry community. The conceptual foundations that are used to understand organic reactivity are based on the transition state theory (TST), which assumes that nuclei behave according to classical mechanics. However, recent evidence has been shown that tunneling is more common than previously thought, even occurring for organic reactions involving the motion of heavy atoms such as carbon. One consequence of the existence of tunneling is the increase of reaction rates in comparison to the expectation based on the classical TST. But tunneling effects can also have much more profound consequences on the chemical reaction outcome, leading to the emerging of new reactivity paradigms that break with the classic TST principles. Our group have have been in the forefront of such discoveries by carried out pioneer investigations on the direct spectroscopic observation of tunneling reactions in low-temperature matrices. Building upon our early research, we will continue to explore new concepts of tunneling reactivity and innovative ways to control it. Complementary to the endeavors on fundamental aspects of tunneling chemistry, will be perform inaugural investigations to include tunneling in synthetic strategies and reaction planning. We aim bring the quantum nature of molecules to the synthetic laboratories and implement research strategies beyond classic paradigms. As a long-term goal, we envision that quantum tunneling driving organic chemistry will create unique opportunities for discovering new and efficient transformations, with potential for opening the door to a universe of molecules hitherto inaccessible 

Representative works:

Simultaneous Tunneling Control in Conformer-Specific Reactions 

Cláudio M. Nunes,* José P. L. Roque, Srinivas Doddipatla, Samuel A. Wood, Robert J. McMahon, and Rui Fausto

J. Am. Chem. Soc. 2022, 144, 20866–20874   (get)   #in ChemistryViews  # in Chemistry World

Switching on H‑Tunneling through Conformational Control  

José P. L. Roque, Cláudio M. Nunes,* Luís P. Viegas, Nelson A. M. Pereira, Teresa M. V. D. Pinho e Melo, Peter R. Schreiner, and Rui Fausto

J.  Am. Chem. Soc. 2021, 143, 8266–8271   (link) (get)   #JACS Spotlight

Heavy‐Atom Tunneling Through Crossing Potential Energy Surfaces: Cyclization of a Triplet 2‑Formylarylnitrene to a Singlet 2,1-Benzisoxazole 

Cláudio M. Nunes,* Luís P. Viegas,* Samuel A. Wood, José P. L. Roque, Robert J. McMahon, and Rui Fausto 

Angew. Chem. Int. Ed. 2020, 59, 17622–17627   (link) (get)   #VIP paper

Competitive Nitrogen versus Carbon Tunneling  

Cláudio M. Nunes,* André K. Eckhardt, Igor Reva, Rui Fausto, and Peter Schreiner  

J. Am. Chem. Soc. 2019, 141, 14340–14348   (link) (get)  

Photochemistry of 2-Formylphenylnitrene: A Doorway to Heavy-Atom Tunneling of a Benzazirine to a Cyclic Ketenimine

Cláudio M. Nunes,* Igor Reva, Sebastian Kozuch, Robert J. McMahon, and Rui Fausto

J. Am. Chem. Soc. 2017, 139, 17649–17659   (link)

In the last two decades, selective IR vibrational excitation in conjugation with supersonic jets or cryogenic matrices conditions has been applied to get exceptional control over organic molecular conformations and to generate elusive conformers otherwise inaccessible to experiments. We have recently demonstrated that bond‑breaking/bond-forming reactions can also be induced by IR vibrational excitation. Surprisingly, the application of this strategy to induce and control organic reactions remains scarcely explored. Building upon our early results, we aim to unravel the potential of IR vibrational excitation to trigger organic reactions and molecular structure manipulations in unprecedented ways. The deposition of vibrational energy in molecules can provide unique opportunities (i) to selective induce reactions in a chosen type of molecules without affecting others or the medium, (ii) to control products distribution overriding the equilibrium thermodynamics, and (iii) to activate high energy reaction pathways instead of the usually observed lower-energy ones. This methodology has therefore a disruptive potential, surpassing the conventional catalytic, thermal, and electronic excitation approaches. Vibrational excitation chemistry will be investigated concomitantly with development of new cutting‑edge strategies to quest fundamental scientific questions and practical applications. As a long-term goal, we envision selective vibrational excitation applied to activate drugs in vivo or to switch optoelectronic devices

Representative works:

Differential Tunneling-Driven and Vibrationally-Induced Reactivity in Isomeric Benzazirines

Cláudio M. Nunes,* Srinivas Doddipatla, Gonçalo F. Loureiro, José P. L. Roque, Nelson A. M. Pereira, Teresa M. V. D. Pinho e Melo, and Rui Fausto

Chem. Eur. J. 2022, 28, e202202306   (link)   #VIP paper

Inducing Molecular Reactions by Selective Vibrational Excitation of a Remote Antenna with Near-Infrared Light

Cláudio M. Nunes,* Nelson A. M. Pereira, Luís P. Viegas, Teresa M. V. D. Pinho e Melo, and Rui Fausto

Chem. Comm.  2021, 57, 9570–9573   (link) (get)

Evidence of IR-Induced Chemistry in a Neat Solid: Tautomerization of Thiotropolone by Thermal, Electronic, and Vibrational Excitations

Nelson A. M. Pereira, Cláudio M. Nunes,* Igor Reva, and Rui Fausto 

J. Phys. Chem. A 2021, 125, 6394–6403   (link) (get)

Switching on H‑Tunneling through Conformational Control  

José P. L. Roque, Cláudio M. Nunes,* Luís P. Viegas, Nelson A. M. Pereira, Teresa M. V. D. Pinho e Melo, Peter R. Schreiner, and Rui Fausto

J.  Am. Chem. Soc. 2021, 143, 8266–8271   (link) (get)   #JACS Spotlight 

Bond-Breaking/Bond-Forming Reactions by Vibrational Excitation: Infrared-Induced Bidirectional Tautomerization of Matrix-Isolated Thiotropolone

Cláudio M. Nunes,* Nelson A. M. Pereira, Igor Reva, Patrícia S. M. Amado, Maria L. S. Cristiano, and Rui Fausto

Phys. Chem. Lett. 2020, 11, 8034–8039   (link) (get) 

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