The NanoSciences Group (GNS) is a multidisciplinary team of chemists, surface physicists and theoreticians. Our goal is to realise, in a single molecule or as few atoms as possible, a complex function such as long-distance information transfer (electronic, optical, magnetic) and a classical or quantum Boolean logic function, mechanical motion and classical <-> quantum transduction.
In order to function, the molecule is integrated into a multi-scale architecture and, ultimately, coplanar with its nano-interconnections. We are developing radical technologies such as the manipulation of individual atoms, or the construction of molecules or 2D arrays by surface chemical synthesis, and we are pushing nano-structuring techniques to the ultimate precision of atomic precision fabrication.
Researchers: Jacques Bonvoisin (CR CNRS), Xavier Bouju (DR CNRS), Olivier Guillermet (MCF UPS), Christian Joachim (DR CNRS), Claire Kammerer (MCF UPS), Gwénaël Rapenne (PR UPS)
Researchers: Christian Joachim (DR CNRS), Claire Kammerer (MCF UPS), Gwénaël Rapenne (PR UPS)
Goal: Putting a single molecule rotor into unidirectional rotary motion
Mastering the rotational motion of molecular motors at the nanometre and single-molecule scale will lead to the design of increasingly small and energy-efficient electronic and mechanical devices (see the European ESiM project).
A motor transforms an energy source into work via a controlled unidirectional rotational motion. The motors synthesised in GNS have been designed to be addressed on a single molecule scale surface using near-field microscopy techniques.
Examples of molecular motors synthesised at CEMES © G. Rapenne CEMES-CNRS/UPS
In collaboration with Prof. Saw-Wai Hla (Ohio University), we studied the electro-induced rotation of one of these motors. By placing the molecule at a temperature of 5 K on a gold surface, we were able to trigger the stepwise movement of the rotor subunit and control its direction of rotation. To do this, we use electrons from the tip of a scanning tunneling microscope (STM), which serves as both an observation instrument and an energy source. As shown in the figure below, the direction of rotation depends on the rotor blade that is positioned under the tip of the microscope at the time of excitation.
The molecular motor is anchored to a surface via three attachment points. The top plate (rotor) rotates back and forth around its axis, depending on the position of the microscope tip.© G. Rapenne and G. Vives, CEMES-CNRS/UPS
A few years later, we developed a new family of molecular motors that are intended to work synchronously at higher temperatures. Ferroelectric behaviour was demonstrated in a self-assembled monolayer on a gold surface with synchronised rotation under the influence of the electric field induced by the STM tip. This rotation occurs over long distances, limited only by the ends of the surface domains.
Synchronised rotation of a self-assembled layer of molecular motors carrying a permanent dipole © G. Rapenne, CEMES-CNRS/UPS
Prototypes of molecular motors based on star-shaped organometallic ruthenium complexes G. Vives, H.P. Jacquot de Rouville, A. Carella, J.P. Launay, G. Rapenne, Chem. Soc. Rev. 2009, 38, 1551-1561. DOI: 10.1039/b804684k
Controlled clockwise and anticlockwise rotational switching of a molecular motor U. Perera, F. Ample, H. Kersell, Y. Zhang, G. Vives, J. Echeverria, M. Grisolia, G. Rapenne, C. Joachim, S.-W. Hla, Nature Nanotech. 2013, 8, 46-51. DOI: 10.1038/NNANO.2012.218
Scorpionate hydrotris(indazolyl)borate ligands as tripodal platform for surface-mounted molecular motors and gears C. Kammerer, G. Rapenne, Eur. J. Inorg. Chem. 2016, 2214-2226. DOI: 10.1002/ejic.201501222
Simultaneous and coordinated rotational switching of all molecular rotors in a network Y. Zhang, H. Kersell, R. Stefak, J. Echeverria, V. Iancu, G. Perera, Y. Li, K.-F. Braun, C. Joachim, G. Rapenne, S.-W. Hla, Nature Nanotech. 2016, 11, 706-713. DOI: 10.1038/nnano.2016.69
A chiral molecular propeller designed for unidirectional rotations on a surface Y. Zhang, J.P. Calupitan, T. Rojas, R. Tumbleson, G. Erbland, C. Kammerer, T.M. Ajayi, S. Wang, L.C. Curtiss, A.T. Ngo, S.E. Ulloa, G. Rapenne, S.W. Hla, Nature Commun. 2019, 10, 3742. DOI: 10.1038/s41467-019-11737-1
A molecular rotor functionalized with a photoresponsive brake R Asato, C.J. Martin, S. Abid, Y. Gisbert, F. Asanoma, T. Nakashima, C. Kammerer, T. Kawai, G. Rapenne, Inorg. Chem. 2021, 60, 3492-3501. DOI: 10.1021/acs.inorgchem.0c03330
2. Nanovéhicules
Chercheurs : Jacques Bonvoisin (CR CNRS), Xavier Bouju (DR CNRS), Olivier Guillermet (MCF UPS), Christian Joachim (DR CNRS), Claire Kammerer (MCF UPS), Gwénaël Rapenne (PR UPS)
Objectif : Contrôler la direction et la vitesse de déplacement d’une molécule sur une surface.
Après la conception d’une brouette moléculaire en 2001 puis sa synthèse et son observation en 2003, nous avons montré en 2007 que lorsque deux roues sont montées sur un essieu, l’une d’elles est capable de tourner sous la poussée de la pointe STM. Expérimentalement, les molécules ont été soigneusement déposées sur une surface de cuivre très propre, et observées au moyen d’un STM. La pointe STM est utilisée à la fois comme une sonde pour capturer une “image” et comme un doigt de taille nanométrique pour déclencher la rotation de la roue.
La brouette moléculaire © GNS-CEMES-CNRS/UPS
Quelques années plus tard, une nanovoiture a été synthétisée et qualifiée pour la Nanocar Race I d’avril 2017. Sa structure chimique est fondée sur un châssis central incurvé et quatre roues. Les molécules ont été sublimées sur une surface d’or et imagées à basse température à l’aide du microscope à effet tunnel du LT-UHV 4-STM. De la spectroscopie tunnel a également été effectuée sur Au(111) afin d’établir une cartographie des résonances proches du niveau de Fermi et d’identifier le port d’entrée d’énergie potentielle sur le squelette moléculaire permettant de déclencher et contrôler un mouvement de la molécule sur la surface.
Nanovoiture qualifiée à la Nanocar Race I © GNS-CEMES, CNRS/UPS
En 2022, une seconde nanovoiture synthétisée à NAIST (Nara, Japon) a participé à la Nanocar Race II les 24-25 mars 2022 (https://www.youtube.com/watch?v=H0r4yNysAdo). L’architecture est cette fois-ci basée sur un châssis porphyrinique, entouré de deux roues triptycène et de deux groupements permettant d’induire un dipôle permanent.
Nanovoiture à structure porphyrinique comportant un dipôle électrique permanent t image de cette molécule-voiture à 2 roues sur la surface Au(111) enregistrée pendant la Nanocar Race II après la négociation d’un virage © GNS-CEMES-CNRS/UPS/NAIST
D’autres modèles de nanovoitures sont à l’étude et en phase de conception notamment sur un modèle de chassis encore différent incorporant une structure du type bis-salophène. L’intérêt ici est l’incorporation de centres métalliques différents incluant ainsi un possible moment dipolaire intramoléculaire permanent.
The design of a mono-molecular barrow
Rolling a single molecular wheel at the atomic scale L. Grill, K. H. Rieder, F. Moresco, G. Rapenne, S. Stojkovic, X. Bouju, C. Joachim, Nature Nanotech. 2007, 2, 95-98. DOI: 10.1038/nnano.2006.210
Molecular Machines : Synthesis and characterization of two prototypes of molecular wheelbarrows G. Rapenne, G. Jimenez-Bueno, Tetrahedron 2007, 63, 7018-7026. DOI: 10.1016/j.tet.2007.05.019
Synthesis of polycyclic aromatic hydrocarbon-based nanovehicles equipped with triptycene wheels H.P. Jacquot de Rouville, R. Garbage, R.E. Cook, A.R. Pujol, A.M. Sirven, G. Rapenne, Chem. Eur. J. 2012, 18, 3023-3031. DOI: 10.1002/chem.201102893
Synthesis and STM imaging of symmetric and dissymmetric ethynyl-bridged dimers of boron-subphthalocyanine bowl-shaped nano-wheels H.P. Jacquot de Rouville, R. Garbage, F. Ample, A. Nickel, J. Meyer, F. Moresco, C. Joachim, G. Rapenne, Chem. Eur. J. 2012, 18, 8925-8928. DOI: 10.1002/chem.201201123
Molecule concept-nanocars : chassis, wheels and motors? C. Joachim, G. Rapenne, ACS Nano, 2013, 7, 11-14. DOI: 10.1021/nn3058246
World’s first nanocar race: a single molecule piloted per team G. Rapenne, C. Joachim, Nature Rev. Mater. 2017, 2, 17040-17042. DOI: 10.1038/natrevmats.2017.40
From the synthesis of nanovehicles to the participation at the first Nanocar Race H.-P. Jacquot de Rouville, C. Kammerer, G. Rapenne, Molecules 2018, 23, 612-623. DOI: 10.3390/molecules23030612
Surface manipulation of a curved polycyclic aromatic hydrocarbon-based nanovehicle equipped with triptycene wheels W.-H. Soe, C. Durand, S. Gauthier, H.-P. Jacquot de Rouville, C. Kammerer, G. Rapenne, C. Joachim, Nanotechnology 2018, 29, 495401. DOI: 10.1088/1361-6528/aae0d9
A dipolar nanocar based on a porphyrin backbone T. Nishino, C.J. Martin, H. Takeuchi, F. Lim, K. Yasuhara, Y. Gisbert, S. Abid, N. Saffon-Merceron, C. Kammerer, G. Rapenne, Chem. Eur. J. 2020, 26, 12010-12018. DOI: 10.1002/chem.202001999
3. Engrenages moléculaires
Chercheurs : Christian Joachim (DR CNRS), Claire Kammerer (MCF UPS), Gwénaël Rapenne (PR UPS)
Objectif : Transférer un mouvement de rotation au sein d’un train d’engrenages moléculaires
La conception et la synthèse de molécules capables d’effectuer des actions mécaniques précises est l’une des clés du développement futur de nano-machineries moléculaires complexes. Dans ce contexte, nous étudions le transfert du mouvement de rotation, idéalement sur de longues distances, au sein de trains d’engrenages moléculaires.
Un train de trois engrenages moléculaires © GNS-CEMES-CNRS/UPS
Dans ce but, nous avons conçu un dispositif moléculaire à crémaillère pour lequel une pointe STM entraîne une seule molécule pignon à basse température. Le pignon est une molécule de 1,8 nm de diamètre fonctionnant comme une roue à six dents, intriquée au bord d’un îlot moléculaire auto-assemblé faisant office de crémaillère. La rotation de la molécule pignon, dent par dent, le long de la crémaillère est mise en évidence grâce à une étiquette chimique dans l’une de ses dents.
Structure de la roue dentée et images STM successives montrant la rotation du pignon (molécule unique) le long du bord de la crémaillère (monocouche auto-assemblée des mêmes molécules © GNS-CEMES-CNRS
Plus récemment, deux de ces molécules ont été montées chacune sur un adatome de cuivre, séparés exactement de 1,9 nm sur une surface de plomb à l’aide d’un microscope à effet tunnel à basse température (LT-STM). Un train fonctionnel de deux engrenages moléculaires a été construit en ajoutant une poignée moléculaire. Sans adatome, cette molécule auxiliaire est en prise mécanique avec la première roue dentée du train d’engrenages pour stabiliser sa rotation pas à pas. Centrée sur son axe en Cu, la rotation de la première roue dentée induit la rotation corrélée de la seconde à la manière d’un train d’engrenages macroscopiques.
Images STM montrant le mouvement corrélé disrotatoire de deux roues dentées ancrées sur des atomes uniques de Cu, lorsqu’elles sont actionnées via une poignée moléculaire. © GNS-CEMES-CNRS
Dans une approche alternative, il est également envisagé d’exploiter un axe métallo-organique comme moyen d’ancrer des roues dentées sur une surface et de construire des trains d’engrenages moléculaires. La conception et la synthèse de deux familles de prototypes d’engrenages moléculaires à base de ruthénium ont récemment été décrites. Ces complexes incorporent un ligand tripode de type hydrotris (indazolyl)borate comme axe de rotation et un ligand pentaarylcyclopentadiényle comme roue dentée en forme d’étoile, équipée de cinq dents allant de groupes aryles pseudo-1D à de grandes pales 2D planes. Une approche synthétique divergente a été suivie, à partir de complexes pentakis(p-halogénophényl) cyclopentadiényl ruthénium(II) comme précurseurs clés. Des réactions de couplage croisé successives avec divers partenaires ont permis d’atteindre une grande diversité structurale et ont conduit à des prototypes symétriques et dissymétriques d’engrenages moléculaires comportant des dents dérivées d’aryle, de carbazole, de BODIPY et de porphyrine de taille et de longueur croissantes.
Un engrenage moléculaire pentaporphyrinique © GNS- CEMES-CNRS/UPS
A rack and pinion device at the molecular scale F. Chiaravalloti, L. Gross, K.-H. Rieder, S. M. Stojkovic, A. Gourdon, C. Joachim, F. Moresco Nature Mater. 2007, 6, 30–33. DOI: 10.1038/nmat1802
Step by step rotation of a molecule-gear mounted on an atomic scale axis C. Manzano, W. -H. Soe, H. S. J. Wong, F. Ample, A. Gourdon, N. Chandrasekhar, C. Joachim Nature Mater. 2009, 8, 576-579. DOI: 10.1038/nmat2467
A Train of Single Molecule-Gears W. H. Soe, S. Srivastava, C. JoachimJ. Phys. Chem. Lett., 10, 6462 (2019).
Star-shaped ruthenium complexes as prototypes of molecular gears G. Erbland, S Abid, Y. Gisbert, N. Saffon-Merceron, Y. Hashimoto, L. Andreoni, T. Guérin, C. Kammerer, G. Rapenne, Chem. Eur. J. 2019, 25, 16328-16339. DOI: 10.1002/chem.201903615
Transmitting stepwise rotation between three molecular gears on the Au(111) surface K.H.A. Yeung, T. Kühne, F. Eisenhut, M. Kleinwächter, Y. Gisbert, R. Robles, N. Lorente, G. Cuniberti, C. Joachim, G. Rapenne, C. Kammerer, F. Moresco, J. Phys. Chem. Lett. 2020, 11, 6892-6899. DOI: 10.1021/acs.jpclett.0c01747
Mechanics of molecule-gears with six long teeth W.-H. Soe, M. Kleinwächter, C. Kammerer, G. Rapenne, C. Joachim, J. Phys. Chem. C 2020, 124, 22625-22630. DOI: 10.1021/acs.jpcc.0c08194
Desymmetrised pentaporphyrinic gears mounted on metallo-organic anchors S. Abid, Y. Gisbert, M. Kojima, N. Saffon-Merceron, J. Cuny, C. Kammerer, G. Rapenne, Chem. Sci. 2021, 12, 4709-4721. DOI: 10.1039/d0sc06379g
Molecular gears from solution to surfaces Y. Gisbert, S. Abid, C. Kammerer, G. Rapenne, Chem. Eur. J. 2021, 27, 12019-12031. DOI: 10.1002/chem.202101489
4. Nanotreuil
Chercheurs : Claire Kammerer (MCF UPS), Gwénaël Rapenne (PR UPS)
Objectif : Intégrer un moteur moléculaire dans une structure de treuil pour pouvoir mesurer son travail.
Nous avons conçu et synthétisé des prototypes de treuils moléculaires dans le but ultime d’étudier le travail effectué par un seul moteur moléculaire à base de ruthénium ancré sur une surface, en sondant sa capacité à tracter une charge lors d’une rotation directionnelle induite par une excitation tunnel inélastique. Selon une approche technomimétique, le moteur a été intégré dans une structure de treuil, avec une longue chaîne polyéthylène glycol flexible terminée par un crochet azoture permettant de connecter une variété de charges moléculaires.
Une méthode en un seul pot impliquant séquentiellement un couplage peptidique et une cycloaddition de Huisgen catalysée au cuivre a permis d’obtenir quatre nanotreuils chargés, reliés à des fragments triptycène, fullerène et porphyrine.
Dispositif expérimental envisagé pour sonder la capacité du moteur à fournir un travail : le moteur à base de ruthénium est intégré dans une structure de treuil moléculaire, permettant de tracter sur la surface une charge moléculaire (en orange) lors de la rotation unidirectionnelle de la sous-unité rotor (en bleu). © GNS- CEMES-CNRS/UPS
Modular synthesis of pentaarylcyclopentadienyl Ru-based molecular machines via sequential Pd-catalysed cross couplings Y. Gisbert, S. Abid, G. Bertrand, N. Saffon-Merceron, C. Kammerer, G. Rapenne, Chem. Commun. 2019, 55, 14689-14692. DOI: 10.1039/C9CC08384G
Divergent synthesis of molecular winch prototypes Y. Gisbert, C. Kammerer, G. Rapenne, Chem. Eur. J. 2021, 27, 16242-16249. DOI: 10.1002/chem.202103126
Researchers: Christian Joachim (DR CNRS), Jacques Bonvoisin (CR CNRS), Xavier Bouju (DR CNRS), Olivier Guillermet (MCF UPS),
Goal: Making a single molecule calculate
Since the beginning of molecular electronics 50 years ago, the scientific challenge has been to make a single molecule calculate by asking it, for example, to add two binary words of two digits each. The aim is then to measure the computing power of the molecule for a given energy consumption. The technological problems associated with this challenge are presented in Physical and Chemical Tools.
1) Molecular wires
In a traditional approach to molecular electronics, one must use molecular wires, i.e. very long conjugated molecules with the smallest possible van der Waals cross-section capable of electronically connecting the active elements of an intramolecular electronic circuit. The conductance G of a molecular wire is defined only when it is brought into moderate electronic interaction with two metallic nanopads at each end. Independently of this semi-classical mono-molecular electronics, several major challenges have been addressed by GNS for the physical chemistry of molecular wires:
(a) The quantum engineering challenge. This involves optimising the electronic structure of the molecular wire so that at low bias voltage of the metal-molecule-metal nano-junction, the decay rate of the conductance G of the molecular wire with length L is as small as possible.
Variation of the decay rate as a function of the product “gap x effective mass” of the tunneling electron for the different chemical structures of molecular wires shown on the right and measured experimentally.
The best current molecular wires have an energy gap between the electronic ground state So and its first excited state S1 of the order of one eV, and a fine optimisation has made it possible to achieve decay rates lower than 0.02 nm-1. GNS thus approaches the hypothetical supra-tunnel effect: a tunneling effect without decay even when the length of the molecular wire increases and this without reaching the electronic states So and S1, thus remaining at a very low bias voltage of the order of 10 mv to 100 mV. This would also avoid the breakdown effects of the nano-junction at higher voltages.
Minimal attenuation for tunneling through a molecular wire
M. Magoga, C. Joachim, Phys. Rev. B, 57, 1820 (1998)
Electron effective mass when tunnelling through a molecular wire
C. Joachim, M. Magoga, Chem. Phys., 281, 347 (2002)
Decay of the molecular wire conductance with length: the role of spectral rigidity
A.Lahmidi, C. Joachim, Chem. Phys. Lett., 381, 335 (2003)
Molecular wires: guiding the super-exchange interaction between 2 electrodes
C.Joachim, M. Ratner, Nanotechnology, 15, 1065 (2004)
Molecular Electronics: Some views on transport, junctions and beyond.
C. Joachim, M. Ratner, PNAS, 102, 8801 (2005)
Hole-Electron Quantum Tunnelling Interferences through a Molecular Junction
M. Portais, C. Joachim, Chem. Phys. Lett., 592, 272 (2014)
Conductance of a single flexible molecular wire composed of alternating Donor and Acceptor units
C.Nacci, F. Ample, D. Bleger, S. Hecht, C. Joachim, L. Grill, Nature Comm., 6, 7397 (2015)
Single and Double Valence Configuration Interactions for recovering the exponential
decay law while tunneling through a molecular wire.
M. Portais, M. Hliwa, C. Joachim, Nanotechnology, 27, 034002 (2016)
Contact Conductance of a graphene nanoribbon with its graphene nanoelectrodes
S. Srivastava, H. Kino, C. Joachim, Nanoscale, 8, 9265 (2016)
(b) The challenge of chemically synthesising long molecular wires initially in solution and then by synthesis on a metal surface and then on the surface of a large gap insulator. Starting with short synthons well synthesised in solution and of extreme purity, surface synthesis first made it possible to reach conjugated molecule lengths inaccessible in solution, as with the series of oligo-acenes and then graphene nanoribbons, before exploring oligomers with a more complex donor-acceptor-donor alternating structure.
Illustration of the synthesis scheme of a long aceno-acene
Tuning the conductance of a molecular wire by the interplay of Donor and Acceptor units.
D. Skidin, T Erdemann, S. Nikipar, F. Eisenhut, J. Kruger, F. Gunther, S. Gemming, A. Kiriy, B. Voit, D.A. Ryndyk, C. Joachim, F. Moresco, G. Cuniberti
Nanoscale, 10, 17131 (2018)
Synthesis and Absorption Properties of Long Acenoacenes
A. Jancarik, D. Mildner, Y. Nagata, M. Banasiewicz, J. Olas, B. Kozankiewicz, J. Holec, A. Gourdon. Chem.-Eur. J., 27, 12388-12394 (2021)
Preparative-scale synthesis of nonacene
Andrej Jančařík, Jan Holec, Yuuya Nagata, Michal Šámal, André Gourdon
Nature Comm. https://rdcu.be/cELtZ (2022)
(c) The challenge of measuring the G-conductance of a single molecule with pico-metric accuracy. The starting point for GNS was first electronic nano-lithography (see Chemical and Physical Tools) and then the broken junction technique. These approaches are not clean enough at the atomic level and have been progressively abandoned by GNS in order to reduce the challenge of nano-fabrication of a metal-molecule-metal nano-junction to a problem of Surface Science to be practiced in ultra-high vacuum. GNS has explored all the ways to bring the orbitals of the last metal atom of the STM tip to reach the molecular orbitals of the molecular wire with a precision better than 10 pm: approaching the tip vertically to the molecule (1995), laterally (2003) or on the contrary retracting it by lifting one of the two ends of the molecule from the surface (2009).
Example of the measurement of the conductance of a long molecular wire as a function of its length L using the pulling technique at very low temperature and in ultra-high vacuum, catching the molecular wire by one end, retracting the tip by a distance Z. The other end remaining on the surface gradually slides off while being detached from the surface unit by unit.
GNS has now switched to 2 STM tips on its LT-UHV 4-STM whose atomic apex to atomic apex distance can be reduced to 60 nm on average and 30 nm in the best cases (2020) with an uncertainty of the order of a nanometre. In parallel, GNS continues to develop a fully planar technology by pushing the via technology towards a UHV quality of the front surface (see Chemical and Physical Tools)
The Electronic Transparency of a Single C60 Molecule.
C. Joachim, J. Gimzewski, R.R. Schlittler, C. Chavy
Phys. Rev. Lett., 74, 2102 (1995)
Electron transport through a metal-molecule-metal junction.
C. Kerguelis, J.P. Bourgoin, J.P. Pallacin, D. Esteve, C. Urbina, M. Magoga, C. Joachim
Phys. Rev. B, 59, 12505 (1999)
Probing the Probing the different stages in contacting a single molecular wire.
F. Morecsco, L. Gross, M. Alemani, K.H. Rieder, H. Tang, A. Gourdon and C. Joachim
Phys. Rev. Lett., 91, 036601 (2003)
The conductance of a single conjugated polymer as a continuous function of its length.
L. Lafferentz, F. Ample, H. Yu, S. Hecht, C. Joachim, L. Grill, Science, 323, 1193 (2009)
Conductance of a single narrow graphene nanoribbon at different electron energy
M. Koch, F. Ample, C. Joachim, L. Grill, Nature Nano., 7, 713 (2012)
Imaging Single atom contact and single Atom manipulation at Low Temperature using
the new ScientaOmicron LT-UHV 4 STM.
J. Yang, D. Sordes, M. Kolmer, D. Martrou, C. Joachim, Eur. Phys. J. AP, 73, 10702 (2016)
For GNS, the major scientific challenge here is to master the intramolecular quantum behaviours and to understand the classical-quantum and quantum-classical conversions in order to determine the best architecture for designing, synthesising and then operating computational molecules one by one. One can choose:
(1) To stick to a classical electronic circuit architecture where each molecule would have either the role of a switch, a diode or a transistor, then to interconnect them by conductive wires with the smallest possible cross-section so that the circuit thus constructed calculates digitally for example,
(2) To integrate all these elementary functions in one and the same large molecule with chemical groups “molecular wire” to cascade them and form the intramolecular electronic circuit which calculates. In GNS, the best molecular wires are developed here, for example in search of the chemical structure of a true molecular quantum bus or the supra-tunnel effect in a more traditional approach,
(3) To design molecules carrying several qubits. It is then arranged that quantum information can be exchanged between these qubits as with the GNS-SWAP molecule,
(4) To abandon the concept of superposition in real space of these elementary components such as switches, diodes, transistors, qubits and molecular wires. In Hilbert space, GNS is looking for another way to superimpose the quantum states of a molecule in order to perform a complex binary calculation. This is called computational electronic states and there is no need to divide a molecule into qubits for this. This is the QHC approach for “Hamiltonian Quantum Computing”.
Electronics using Hybrid- Molecular and Mono- Molecular Devices,
C. Joachim, J.K. Gimzewski, A. Aviram, Nature, 408, 541 (2000)
Bonding more atoms together for a single molecule to compute,
C. Joachim, Nanotechnology, 13, R1 (2002)
Quantum Design rules for single molecule logic gates
N. Renaud, M. Hliwa, C. Joachim, Phys. Chem. Chem. Phys., 13, 14404 (2011)
For (1), this is hybrid molecular electronics where GNS has studied a large number of switch molecules i.e. whose G conductance can be modified by applying an external stimulus directly to the molecule: compression of the molecule by pressing on it with the tip of the STM, application of an electric field, increase of the tunnel current or chemical reduction of the molecule to trigger a stable conformational change on the support surface as shown below with 2 Cudbm2 molecules Most often the conductance under the STM tip varies by several orders of magnitude as in the transition from (a) to (b) for the Cu-dbm2 molecule on the right in the figure below.
Succession of STM images showing the reversible switching of two Cudbm2 molecules using the microscope tip. These are two Bis-dibenzoylmethanato-Cu molecules in the square planar conformation [Cu(II)dbm2](0) (STM image (a)) then one in the tetrahedral conformation [Cu(I)dbm2](-1) after its reduction and the other still in the square planar conformation (STM image (b)).
In order to build a Boolean logic function with these switches, they must each be connected to at least 2 conductive nano-electrodes which are themselves interconnected on an insulating flat surface by very short conductive wires with the smallest possible cross-section (see Chemical and Physical Tools). As shown below with the 2 C60 amplifiers (blue circle) mounted in “saturated-blocked”, GNS has demonstrated that a simple logic function like the NOR gate can be constructed. This is a relatively modest miniaturisation compared to the miniaturisation of modern semiconductor transistors. These switch-molecules are relevant for example to explore the kTLog2 switching energy limit predicted by R. Landauer for a stable two-state switch when its support surface is maintained at a temperature T.
NOR logic gate designed with 2 amplifiers (blue) each using a single C60 molecule and interconnected by conductor wires of the smallest possible cross-section with a minimum length of about 10 nm for a metal wire and for an operating temperature at ambient.
An electromechanical amplifier using a single molecule.
C. Joachim, J.K. Gimzewski, Chem. Phys. Lett., 265, 353 (1997).
Physical Principles of the single C60 transistor effect.
C. Joachim, J.K. Gimzewski, H. Tang
Phys. Rev. B, 58, 16407 (1998)
Logic gates and memory cells based on single C60 electromechanical transistor.
S. Ami, C. Joachim, Nanotechnology, 12, 44 (2001)
Controlling the Charge State of a Single Redox Molecular Switch
T. Leoni, O. Guillermet, H. Walch, V. Langlais, A. Scheuermann, J. Bonvoisin, S. Gauthier
Phys. Rev. Lett. 106, 216103 (2011)
Mechanical conformation switching of a single pentacene molecule on Si(100)-2×1.
O.A. Neucheva, F. Ample, C. Joachim, J. Phys. Chem. C, 49, 117 (2013).
For (2), this is semi-classical single-molecule electronics. In this case, a circuit molecule is designed as an electron scientist would by chemically linking active molecular groups (molecular diode, molecular switch and possibly molecular transistors) in a single molecule using molecular wire groups. The example below is an intramolecular circuit using in a single molecule 2 molecular diode groups (left) and various molecular wires. This molecule functions as a Boolean AND logic gate with 2 inputs and 1 output.
Exemple de la structure chimique d’une molécule-circuit AND structurée autour de 2 diodes moléculaire. Cette fonction AND demande 4 nano-plots métallique (extrémité atomique indiquée en vert) (Chem. Phys. Lett.,367, 662 (2003)).
This approach has been progressively abandoned by GNS since, in order to preserve the functionality of each functional molecular grouping, it is imperative to chemically link them by saturated bonds which limits the operating current to a few pA even for the simple AND gate given above. Moreover, there is no power gain possible inside such a molecule-circuit except to take the logic signal out of the molecule by connecting one or more metal nanopads at the right place.
Towards circuitry in a tunnel barrier
M. Magoga, C. Joachim, Phys. Rev. B, 59, 16011 (1999)
Intramolecular circuits connected to N electrodes
S. Ami, C. Joachim, Phys. Rev. B, 65, 155419 (2002)
Molecular “OR” and “AND” logic gates integrated in a single molecule
S. Ami, M. Hliwa, C. Joachim, Chem. Phys. Lett., 367, 662 (2003)
A Semi-classical XOR Logic gate integrated in a single molecule
N. Jlidat, M. Hliwa, C. Joachim, Chem. Phys. Lett., 451, 270 (2008)
A molecule OR logic gate with no molecular rectifier
N. Jildat, M. Hliwa, C. Joachim, Chem. Phys. Lett., 470, 275 (2009)
For (3), the aim is to bring molecular electronics into the realm of quantum computing with qubits arranged in the right place within the same molecular structure. Based on the experience of GNS in the field of molecular magnetism and mixed valence complexes, the chemical structure of a SWAP molecule has been proposed. As presented below, it is a low-spin paramagnetic organometallic complex with four centres. The magnetic super-exchange interaction between the 2 intramolecular qubits located on M1 and M2 depends on the oxidation state of the third intermediate M3 centre, which is itself controlled by a gap electron transfer process between the M3 and M4 sites.
Structure of the 3-qubit SWAP molecule (left) proposed by the GNS group and its operating principle (right).
A model system was constructed using spin-intricate qubits in the framework of a Heisenberg-Dirac-Van Vleck spin Hamiltonian demonstrating the efficient exchange operation of this complex. GNS has demonstrated that this 4-centre molecule functions as a SWAP logic gate of controlled quantum exchange.
A controlled Quantum SWAP logic gate in a 4-Center metal complex
M. Hliwa, J. Bonvoisin and C.Joachim
In “Architecture & Design of Molecule Logic Gates and Atom Circuits”
Springer Series: Advances in Atom and Single Molecule Machines:
Vol. II, p. 237 (2013), ISBN 978-3-642-33136-7
For (4), it is about single-molecule quantum electronics. With its QHC approach, GNS is able to generate quantum graphs realising all the 2-in-1-out logic gates without qubits, most of which have now been verified experimentally with starphene-type molecules.
Example of the chemical structure of a first generation QHC Boolean logic gate molecule with these 2 mechanical inputs (Chem. Phys. Lett, 452, 269 (2008)).
The second generation QHC logic gate invented by GNS avoided the need to pass the readout current through the entire molecular structure as was the case with the first generation shown above. The measurement of the logic output then becomes local. Starting from the simplest QHC quantum graph given on the left below with 3 computational states, GNS managed to build more complex graphs circled in red below with on the top right the graph that gave rise to QHC circuits etched atom by atom on the surface of Si(100)H and on the bottom right the QHC graph of an implantable ½ adder gate in a graphene sheet.
Starting from the universal QHC graph with 3 quantum states and 2 read states the different second generation QHC quantum graphs leading to the ½ binary adder.
GNS has experimentally demonstrated that a single well-designed molecule using intramolecular magnetic effects is a binary 3-input-2-output QHC adder. This is the most complex digital function ever embedded in a single molecule (see Figure above). In a conventional architecture, 14 switches or transistors would be required. In a traditional quantum computer, 4 qubits would be required to obtain the same Boolean function.
The molecular structure of the 1,8,9,16,17,24-hexaazatrianthracene molecule used and the position of its 3 single-atom Al logic inputs. Four LT-UHV STM dI/dV maps are presented. They were recorded at maximum tunnel resonance |So> for the 4 particular logic input configurations shown. The results of the logic calculation performed by this QHC molecule logic gate are measured by positioning the apex of one of the tips of my LT-UHV 4-STM on the central phenyl (red cross): the sum is tracked at +10 mV (the Kondo resonance) and the restraint at -750 mV (see hal-03412802v1 for more details) Each Al atom can be manipulated independently by the apex of the STM tip in a repulsive or attractive mode of manipulation on the Au(111) surface used for this experiment.
GNS now seeks to determine the molecular structure of a full adder of 2 binary words of 2 digits each and thus to understand the rules for climbing in complexity in Hilbert space without cascading elementary QHC gates.
A quantum digital half adder inside a single molecule
I. Duchemin, C. Joachim, Chem. Phys. Lett., 406, 167 (2005)
An intramolecular digital ½ adder with a tunneling current drive and reads out
I. Duchemin, N. Renaud, C. Joachim, Chem. Phys. Lett., 452, 269 (2008)
The design and stability of NOR and NAND logic gates constructed with only 3 quantum states.
N. Renaud, C. Joachim, Phys. Rev. A, 78, 062316 (2008)
Manipulating molecular quantum states with classical metal atom inputs : demonstration of a single molecule NOR logic gate.
W.H. Soe, X. Manzano, N. Renaud, P. De Mandoza, A. De Sarkar, F. Ample, M. M.Hliwa,
A.M. Echevaren, N. Chandrasekhar, C. Joachim, ACS Nano, 5 ,1436 (2011)
Realization of a Quantum Hamiltonian Computing Boolean logic gate on the Si(001):H surface.
M. Kolmer, R. Zuzak, S. Godlewski, M. Szymonski, G. Dridi, C. Joachim
Nanoscale, 7, 12325 (2015)
The Mathematics of a QHC ½ adder Boolean Logic Gate.
G. Dridi, R. Julien, M. Hliwa, C. Joachim, Nanotechnology, 26, 344003 (2015)
Quantum Half-Adder Boolean Logic Gate with a Nano-Graphene molecule and
Graphene electrodes.
S. Srivastava, H. Kino, C. Joachim, Chem. Phys. Lett., 667, 301 (2017)
Qubits and Quantum Hamiltonian Computing Performances for Operating Digital Boolean 1/2–adder.
G. Dridi, O. Faizy, C. Joachim, Quantum Science and Technology, 3, 025005 (2018).
Unimolecular NAND logic gate with classical input by single Au atoms.
D. Skidin,O. Faizy, J. Krüger, F. Eisenhut, A. Jancarik, K.H Nguyen, G. Cuniberti, A. Gourdon, F. Moresco, C. Joachim, ACS Nano, 12, 1139 (2018)
Quantum Hamiltonian Computing protocols for molecular electronics Boolean logic gates
O. Faizy, O. Giraud, B. Georgeot, C. Joachim, Quantum Science & Technology, 4, 035009 (2019)
A Tetrabenzophenazine Low Voltage Single Molecule XOR Quantum Hamiltonian Logic Gate
W.H. Soe, C. Manzano, C. Joachim, Chem. Phys. Lett., 478, 137388 (2020)
A Single Molecule Full Digital Adder
W.H. Soe, P. de Mendoza, A.M. Echavarren,, C.Joachim, J. Phys. Chem. Lett, 12, 8528–8532 (2021)
The GNS group has 8 chemistry laboratories (a total of 14 fume hoods) fully equipped for all types of synthesis in molecular chemistry (organic, coordination, organometallic).
We also have an electrochemical system coupled to a UV-Vis-PIR spectrometer, an EMC microwave reactor, a -70°C cryostat, a flash chromatography system (SPOT 2), etc.
The GNS group is a member of the Toulouse Chemistry Institute (UAR2599, https://ict.cnrs.fr/) and has access to its technical platform (NMR, HPLC, mass spectrometry, crystallography, Mössbauer spectroscopy, …).
For its experiments on a single molecule in mechanics and electronics, the GNS group has several tunneling microscopes (STM) and non-contact atomic force microscopes (nc-AFM) operating in ultra-high vacuum and at low temperature (see ATP platform).
It also has an ultra-high vacuum clean room (UHV) where the following are accessible along an 8 m long ultra-high vacuum service tube: an MBE, a mass spectrometer refitted as a molecule sublimator with a mass filter, a VT-STM from Scienta-Omicron and an nc-AFM also from Scienta-Omicron (see ATP platform). GNS also designed and had Scienta-Omicron build a 4 STM ultra-high vacuum and low temperature microscope, with an electron microscope operating in ultra-high vacuum. It has been operational since mid-2015 (see ATP platform) and hosted the first international molecule-car race in April 2017
The Pico-Lab white room at CEMES has been designed by GNS to host future developments in planar and picometrically precise molecular-mechanical technology and classical and quantum mono-molecular electronics. In particular, the processes are to be developed (see Atom Tech process roadmap in ATP platform):
– Atom Tech chips (1st Generation): Peer-to-peer and UHV suitcase (2012 – 2025)
– Atom Tech chips (2nd Generation): Fully integrated DUF clean room (2020-2030)
The GNS group is a member of the GdR NEMO (New Molecular Electronics). Xavier Bouju is the contact point for GNS (https://nemo.cnrs.fr/).
The GNS group coordinates the GDR NS-CPU- (Nanoscience Champ Proche Ultravide). David Martrou is the leader (https://www.nanosciences-spm-uhv.com/).
A reliable scheme for fabricating sub-5 nm co-planar junction for molecular electronics
MSM Saifullah, T. Ondarcuhu, D.F. Koltsov, C. Joachim, M. Welland,
Nanotechnology, 13, 659 (2002)
UHV-STM Manipulation of Single Au nano-island on MoS2 for the construction of planar
nano interconnects, J.S. Yang, D. Jie, N. Chandrasekar, C. Joachim,
J. Vac. Sci. Tech. B, 25, 1694 (2007)
Single molecular wires connecting metallic and insulating surface area
C. Bombis, F. Ample, L. Lafferentz, H. Yu, S. Hecht, C. Joachim, L. Grill
Ang. Chem. Int. Ed. 48, 9966 (2009)
Multiple Atomic scale solid surface interconnects for atom circuits and molecule logic gates
C. Joachim, D. Martrou, M. Rezeq, C. Troadec, Deng Jie, N. Chandrasekhar, S. Gauthier
J. Phys. CM, 22, 084025 (2010)
Direct transfer of Au nano-ilslands from a MoS2 stamp to an SiH surface
J. Deng, C. Troadec, H.K. Kim, C. Joachim
J. Vac. Sci. Tech. B., 28, 484 (2010)
Backside Interconnect fabrication for atomic and molecular scale circuits
M.H.T. Lwin, T.N. Tun, H.H. Kim, R.S. Kajen, N. Chandrasekhar, C. Joachim
J. Vac. Sci. Tech. B, 28, 978 (2010)
Atomic scale fabrication of dangling bond structures on hydrogen passivated Si(001)
wafers processed and nanopackaged in a clean room environment
M. Kolmer, S. Godlewski, R. Zuzak, M. Wojtaszek, C. Rauer, A. Thuaire, J.M. Hartmann,
H. Moriceau, C. Joachim, M. Szymonski,, Appl. Surf. Sci., 288, 83 (2014)
To understand how a molecule-machine performs the function envisaged by its design (for mechanics, calculation as a logic gate…), calculations and numerical simulations are necessary. Not only to predict the behaviour of the molecule but also to compare with experimental results. These calculations must take into account a very often large number of atoms in the systems considered (molecule + surface + STM tip). Semi-empirical methods of the extended Hückel type are used, but also semi-classical force fields or DFT when possible. We are therefore required to carry out mechanical/molecular dynamics type calculations to determine the conformations of adsorbed molecules (ASED+, VASP, MM4), STM image calculations (ESQC-EHMO) and the electric field in the STM junction, the conductance of a molecule, etc.
A tetrabenzophenazine low voltage single molecule XOR quantum Hamiltonian logic gate
W.-H. Soe, C. Manzano, C. Joachim
Chem. Phys. Lett. 748, 137388 (2020)
Train of Single Molecule-Gears
W.-H. Soe, S. Srivastava, and Christian Joachim
J. Phys. Chem. Lett. 10, 6462 (2019)
Surface Vacancy Generation by STM Tunneling Electrons in the Presence of Indigo Molecules on Cu(111)
C. J. Villagómez, F. Buendía, L. O. Paz-Borbón, B. Fuentes, T. Zambelli, and X. Bouju
J. Phys. Chem. C 126, 14103 (2022)
Planar bridging an atomically precise surface trench with a single molecular wire on an Au(111) surface
U. Thupakula, X. Bouju, J. Castro-Esteban, E. Dujardin, D. Peña, C. Joachim
Chem. Phys. Lett. 806, 140029 (2022)
On the left, the relaxed conformation of an indigo molecule after a double voltage pulse with the STM tip. In the middle, the corresponding calculated STM image. On the right, the experimental STM image of a single molecule.
Controlled reactivity of sulphoxides on insulating surfaces (CROSS)
PRC ANR 2021-2025
Researchers in CEMES: Jacques Bonvoisin (CR CNRS), Claire Kammerer (MCF UPS), Gwénaël Rapenne (PR UPS)
Partners:
– D. Madec, E. Maerten, O. Thillaye du Boullay (équipe ECOIH du LHFA, Toulouse – https://www.lhfa.cnrs.fr/index.php/equipes/ecoih)
– S. Clair, C. Loppacher, L. Nony (équipe Nanostructuration de l’IM2NP, Marseille – https://www.im2np.fr/fr/equipe-nanostructuration-nano)
Surface synthesis has emerged as a powerful approach for the formation of new functional nanomaterials, inaccessible by conventional solution synthesis methods. Complex nanoarchitectures with various structural, chemical, optoelectronic and magnetic properties have been obtained in a controlled manner from specifically designed molecular precursors.
In the field of surface synthesis, research has so far focused mainly on the assembly of one- or two-dimensional covalent networks by intermolecular coupling. As in conventional “solution” chemistry, it would be beneficial to enrich the toolbox of surface synthesis with new reactivities, so as to be able to perform in-situ functional modifications on nanostructures and thus allow a fine modulation of their properties.
In addition, the vast majority of surface synthesis reactions are carried out on metal substrates, in order to take advantage of their catalytic activity and their compatibility with scanning tunneling microscopy, which allows direct characterisation of the products. However, metal surfaces considerably modify the optoelectronic properties of the adsorbed species, which limits the reactivity of the precursors and the functionality of the products. Insulating substrates therefore appear as an alternative of choice for surface synthesis, allowing the intrinsic optoelectronic properties of the newly formed structures to be probed for optimisation and future applications.
With an original multidisciplinary approach combining studies in solution and on surfaces, the CROSS project aims to develop new tools for synthesis on insulating surfaces, exploiting photoactive polar sulphoxides as sacrificial chemical reagents to induce selective in-situ reactions.
HORIZON-EIC n. 101046363 European contrac
“Energy Storage in Molecule(s)” (ESiM) 2022-2026
Researchers in CEMES: Christian Joachim (DR CNRS), Xavier Bouju (DR CNRS), Olivier Guillermet (MCF UPS), David Martrou (CRN-CNRS) with Jimmy Faria (IE CNRS)
Partners:
TU Dresden (Allemagne),
CNRS (Groupe GNS-CEMES) (France)
Centro de Fisica de Materiales, San Sébastien CSIC (Espagne)
Int. Polymers Forshung Dresde (Allemagne)
Uni. Groningen (Hollande)
Instituto de Ciencia de Materiales, Barcelone CSIC (Espagne)
The ESiM strategy is to use the conformational degrees of freedom of certain molecule-rotors and molecule-switches to pump energy from a surface on a molecule-by-molecule basis and then create two-dimensional molecular networks to multiply the energy storage effects. We want to provide proof that energy storage in a molecule is feasible by going on another hunt for Maxwell’s Demon. The role of GNS here is to design rotor molecules with rotational asymmetry (clockwise – anti-clockwise) by exploring the mixing of fundamental and excited potential energy surfaces where the excited electronic state has a conical intersection or more simply an angular shift between the fundamental maximum and the excited minimum. Molecules will be designed and synthesised by ESiM chemists to try to take advantage of a possible deviation from the micro-reversibility principle. Then we will explore how it is possible to pump energy from a surface and store it in a few specific intramolecular mechanical degrees of freedom. Then, 2D molecular layers creating molecular nanopores will be developed to efficiently store this energy on the surface. As a proof of principle, an LT-UHV device will be constructed based on a bimetallic lever arm to pump and store energy from surface active molecules of this lever arm.
Charge transport in modulatable heterometallic self-assemblies composed of nanoparticles and coordination complexes (THERESA)
Collaborative project NanoX 2021-2024
Researchers in CEMES: Jacques Bonvoisin (CR CNRS), Claire Kammerer (MCF UPS), Gwénaël Rapenne (PR UPS)
Partners:
S. Tricard, A. Pham (LPCNO, Toulouse – http://lpcno.insa-toulouse.fr/spip.php?article594&lang=fr)
The THERESA project aims to develop nanometrically structured hybrid materials resulting from self-assemblies between ultra-small nanoparticles and molecular entities, and then to optimise their charge transport properties. The use of porphyrin or bisalophen coordination complexes (homo- or heterobimetallic) will make it possible to modulate the polarizability of the molecular entities within the self-assemblies and to exploit their possible luminescence properties.
«GNR Conductance» 2021-2022
Researchers in CEMES: Christian Joachim (DR CNRS)
We measure the intrinsic electronic conductance of a single graphene nanoribbon (GNR) electronically decoupled from its support surface and in a fully planar configuration using the LT-UHV 4-STM of the GNS group with two of its STM tips. For this purpose, 7-GNRs with a width of ~ 1-2 nm and a length between 20-50 nm but with a low coverage rate were first synthesized on the Au(111) surface. We will then use intermediate atomic thin films of sodium chloride (NaCl) to electronically decouple the GNR from the Au(111) surface during conductance measurements. The substrate will then be electrically disconnected from the ground. The z-accuracy of the LT-UHV 4-STM per tip will allow the different types of contact between the atomic apex of a tip and the end of a 7-GNR to be monitored as a function of the tip-to-7-GNR distance: tunneling, van der Waals, chemical and mechanical. For this purpose, the current-distance I(z) characteristics at the 7-GNR will be recorded. Particular care is taken by GNS in the FIB fabrication of the apex of each tip to achieve the smallest possible atomic apex to atomic apex distance (current world record 33 nm but not very reproducible). One could then engage in 3-point STM tunnel potentiometry and make dI/dV differential conductance maps with or without the 7-GNR connected.
Scanning tunneling microscopy and local electric field effect (STEFE)
Collaborative project NanoX 2020-2023
Researchers in CEMES: Xavier Bouju (DR CNRS)
Partners:
Iann Gerber (LPCNO, INSA-Toulouse)
The STEFE project aims at studying, mainly theoretically, the local electric field (EF) inside a scanning-tunneling-microscope (STM) junction. This EF is usually generated by a bias voltage applied between the local probe and the metallic substrate. Due to the tip shape, a more or less strong enhancement of the EF exists beneath the apex and can modify the adsorption state of a single atom or a single molecule according to the bias voltage and the tip-surface distance. Without an atomic-scale description of the tip apex and its effects on the adsorbates, the EF effect remains unclear. We plan to rationalize the possible EF enhancement in various situations with the help of DFT calculations, as well as a N-body order method. We shall apply our numerical methodology to molecular adsorbates with an increasing complexity, starting with single atoms to complexe molecules dedicated to the NanoCar Race 2022 (NCR22).
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