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Baklanov A, Garnica M, Robert A, Bocquet ML, Seufert K, Küchle JT, Ryan PTP, Haag F, Kakavandi R, Allegretti F, Auwärter W. On-Surface Synthesis of Nonmetal Porphyrins. J Am Chem Soc 2020; 142:1871-1881. [PMID: 31944105 DOI: 10.1021/jacs.9b10711] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
We report the on-surface synthesis of a nonmetal porphyrin, namely, silicon tetraphenylporphyrin (Si-TPP), by the deposition of atomic silicon onto a free-base TPP layer on a Ag(100) surface under ultrahigh vacuum (UHV) conditions. Scanning tunneling microscopy provides insights into the self-assembly of the TPP molecules before and after Si insertion. Silicon coordinates with all four nitrogen atoms of the TPP macrocycle and interacts with a silver atom of the substrate as confirmed by scanning tunneling spectroscopy, X-ray photoelectron spectroscopy, and complementary density functional theory calculations. The Si-TPP complex presents a saddle-shaped conformation that is stable under STM manipulation. Our study shows how protocols established for the on-surface metalation of tetrapyrroles can be adopted to achieve nonmetal porphyrins. Complementary experiments yielding Si-TPP and Ge-TPP on Ag(111) highlight the applicability to different main group elements and supports. The success of our nonmetal porphyrin synthesis procedure is further corroborated by a temperature-programmed desorption experiment, revealing the desorption of Ge-TPP. This extension of interfacial complex formation beyond metal elements opens promising prospects for new tetrapyrrole architectures with distinct properties and functionalities.
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Affiliation(s)
- Aleksandr Baklanov
- Physics Department E20 , Technical University of Munich , James-Franck-Str. 1 , D-85748 Garching , Germany
| | - Manuela Garnica
- Physics Department E20 , Technical University of Munich , James-Franck-Str. 1 , D-85748 Garching , Germany
| | - Anton Robert
- PASTEUR, Département de Chimie, École Normale Supérieure , PSL University, Sorbonne Université, CNRS , 75005 Paris , France
| | - Marie-Laure Bocquet
- PASTEUR, Département de Chimie, École Normale Supérieure , PSL University, Sorbonne Université, CNRS , 75005 Paris , France
| | - Knud Seufert
- Physics Department E20 , Technical University of Munich , James-Franck-Str. 1 , D-85748 Garching , Germany
| | - Johannes T Küchle
- Physics Department E20 , Technical University of Munich , James-Franck-Str. 1 , D-85748 Garching , Germany
| | - Paul T P Ryan
- Diamond Light Source , Harwell Science and Innovation Campus , Didcot OX11 0DE , U.K.,Department of Materials , Imperial College London , South Kensington, London , SW7 2AZ , U.K
| | - Felix Haag
- Physics Department E20 , Technical University of Munich , James-Franck-Str. 1 , D-85748 Garching , Germany
| | - Reza Kakavandi
- Physics Department E20 , Technical University of Munich , James-Franck-Str. 1 , D-85748 Garching , Germany
| | - Francesco Allegretti
- Physics Department E20 , Technical University of Munich , James-Franck-Str. 1 , D-85748 Garching , Germany
| | - Willi Auwärter
- Physics Department E20 , Technical University of Munich , James-Franck-Str. 1 , D-85748 Garching , Germany
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Néel N, Lattelais M, Bocquet ML, Kröger J. Depopulation of Single-Phthalocyanine Molecular Orbitals upon Pyrrolic-Hydrogen Abstraction on Graphene. ACS NANO 2016; 10:2010-6. [PMID: 26812093 DOI: 10.1021/acsnano.5b06153] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Single-molecule chemistry with a scanning tunneling microscope has preponderantly been performed on metal surfaces. The molecule-metal hybridization, however, is often detrimental to genuine molecular properties and obscures their changes upon chemical reactions. We used graphene on Ir(111) to reduce the coupling between Ir(111) and adsorbed phthalocyanine molecules. By local electron injection from the tip of a scanning tunneling microscope the two pyrrolic H atoms were removed from single phthalocyanines. The detachment of the H atom pair induced a strong modification of the molecular electronic structure, albeit with no change in the adsorption geometry. Spectra and maps of the differential conductance combined with density functional calculations unveiled the entire depopulation of the highest occupied molecular orbital upon H abstraction. Occupied π states of intact molecules are proposed to be emptied via intramolecular electron transfer to dangling σ states of H-free N atoms.
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Affiliation(s)
- Nicolas Néel
- Institut für Physik, Technische Universität Ilmenau , D-98693 Ilmenau, Germany
| | - Marie Lattelais
- Department of Chemistry, UMR ENS-CNRS-UPMC 8640, Ecole Normale Supérieure , F-75005 Paris, France
| | - Marie-Laure Bocquet
- Department of Chemistry, UMR ENS-CNRS-UPMC 8640, Ecole Normale Supérieure , F-75005 Paris, France
| | - Jörg Kröger
- Institut für Physik, Technische Universität Ilmenau , D-98693 Ilmenau, Germany
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Burema SR, Bocquet ML. Sensitizers in inelastic electron tunneling spectroscopy: a first-principles study of functional aromatics on Cu(111). NANOTECHNOLOGY 2012; 23:315702. [PMID: 22797417 DOI: 10.1088/0957-4484/23/31/315702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Low sensitivity is a key problem in inelastic electron tunneling spectroscopy (IETS) with the scanning tunneling microscope. Using first-principles simulations, we predict different means to tune the IETS sensitivity of symmetrical functional aromatics on a Cu(111) surface. We show how the IET-spectra of phenyl-NO₂ compounds can be greatly enhanced as compared to pristine phenyl. More precisely, the NO₂ substituent qualifies as a sensitizer of low-frequency wagging modes, but also as a quencher of high-frequency stretching modes. At variance, the CO₂ substituent is found to suppress the whole IET-activity. The head-up (non-anchoring) and head-down (anchoring) configurations of the functional group lead to minor changes in the signals, nevertheless allowing access to discriminate configurational features. It is shown how to disentangle the electronic and steric effects of the substituent in the STM junction.
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Affiliation(s)
- S R Burema
- Laboratoire de Chimie, Ecole Normale Supérieure de Lyon, Université de Lyon, CNRS, France
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Burema SR, Lorente N, Bocquet ML. A theoretical rationalization of a total inelastic electron tunneling spectrum: the comparative cases of formate and benzoate on Cu(111). J Chem Phys 2012; 136:244507. [PMID: 22755587 DOI: 10.1063/1.4730168] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Inelastic electron tunneling spectroscopy (IETS) performed with the scanning tunneling microscope (STM) has been deemed as the ultimate tool for identifying chemicals at the atomic scale. However, direct IETS-based chemical analysis remains difficult due to the selection rules that await a definite understanding. We present IETS simulations of single formate and benzoate species adsorbed in the same upright bridge geometry on a (111)-cleaved Cu surface. In agreement with measurements on a related substrate, the simulated IET-spectra of formate/Cu(111) clearly resolve one intense C-H stretching mode whatever the tip position in the vicinity of the molecular fragment. At variance, benzoate/Cu(111) has no detectable IET signal. The dissimilar IETS responses of chemically related molecules--formate and benzoate adsorbates--permit us to unveil another factor that complements the selection rules, namely the degree of the vacuum extension of the tunneling active states perturbed by the vibrations. As a consequence, the lack of a topmost dangling bond orbital is entirely detrimental for STM-based inelastic spectroscopy but not for STM elastic imaging.
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Affiliation(s)
- S R Burema
- Ecole Normale Supérieure de Lyon, Laboratoire de Chimie, CNRS UMR 5182, 46 Allée d'Italie, 69364 Lyon Cedex 07, France
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