Role of the Anchored Groups in the Bonding and Self-Organization of Macrocycles: Carboxylic versus Pyrrole Groups

González-Moreno, Rubén; García-Lekue, Aran; Arnau, A.; Trelka, Marta; Gallego, José M.; Otero, Roberto; Verdini, Alberto; Sánchez‐Sánchez, Carlos; Andrés, Pedro L. de; Martín‐Gago, José A.; Rogero, Celia

doi:10.1021/jp4005949

Cited by 8 publications

(17 citation statements)

References 61 publications

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“…In the adsorbed state, this leads to a competition between the energydecreasing maximization of the adsorbate-substrate contact, which forces the molecule to approach a planar conformation, and the energy-increasing intramolecular strain resulting from the distortion towards planarity. The balance between these two conflicting trends eventually determines the equilibrium [443] conformation of the adsorbed porphyrin, and it is obvious that this (often rather complex) conformation will be influenced both by the molecular structure and the adsorbate-substrate interaction.…”

Section: Porphyrinsmentioning

confidence: 99%

“…Covalent tethering of porphyrins to metal surfaces through reactive anchoring groups at the periphery of the molecules was performed with protoporphyrin IX (2HPPIX, Fig. 4c) [443,444] and with various other porphyrins using anchor groups on the basis of thiols [445], disulfides [446], acetylthiols [447][448][449][450][451], and others [452,453]. In some cases, electronic decoupling from the (metal) substrate was desired, for example to avoid quenching of excited states by substrate influences in the context of photochemistry.…”

Section: Tetrapyridylporphyrinsmentioning

confidence: 99%

“…The porphyrin was metalated by substrate Cu atoms at room temperature (cf. Section 6.2) [443,444]. The tethered 2HPPIX molecules formed ordered self-assembled structures, in which the linker group of each molecule was buried under the porphyrin macrocycle of the adjacent molecule [443].…”

Section: Tetrapyridylporphyrinsmentioning

confidence: 99%

“…Section 6.2) [443,444]. The tethered 2HPPIX molecules formed ordered self-assembled structures, in which the linker group of each molecule was buried under the porphyrin macrocycle of the adjacent molecule [443]. An insitu electrospray technique was used for the deposition of ZnPPIX onto rutile TiO 2 (1 1 0) in vacuum.…”

Section: Tetrapyridylporphyrinsmentioning

confidence: 99%

“…Metalation by substrate metal atoms, sometimes termed "self-metalation", has also been studied on Cu surfaces [433,434,443,444,509,[710][711][712][713]. The reaction of 2HP and 2HTPP with a Cu(1 1 1) surface was studied in great detail by Diller et al [433,434] using LT-STM, XPS and NEXAFS.…”

Section: Reaction With Pre-deposited or Substrate Metal Atomsmentioning

confidence: 99%

See 4 more Smart Citations

Surface chemistry of porphyrins and phthalocyanines

Gottfried

2015

Surface Science Reports

571

586

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Section: Porphyrinsmentioning

confidence: 99%

Section: Tetrapyridylporphyrinsmentioning

confidence: 99%

Section: Tetrapyridylporphyrinsmentioning

confidence: 99%

Section: Tetrapyridylporphyrinsmentioning

confidence: 99%

Section: Reaction With Pre-deposited or Substrate Metal Atomsmentioning

confidence: 99%

See 3 more Smart Citations

Surface chemistry of porphyrins and phthalocyanines

Gottfried

2015

Surface Science Reports

571

586

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2H‐Tetrakis(3,5‐di‐tert‐butyl)phenylporphyrin on a Cu(110) Surface: Room‐Temperature Self‐Metalation and Surface‐Reconstruction‐Facilitated Self‐Assembly

Zhang

Lepper

Stark

et al. 2016

Chemistry A European J

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The adsorption behavior of 2H-tetrakis(3,5-di-tert-butyl)phenylporphyrin (2HTTBPP) on Cu(110) and Cu(110)-(2×1)O surfaces have been investigated by using variable-temperature scanning tunneling microscopy (STM) under ultrahigh vacuum conditions. On the bare Cu(110) surface, individual 2HTTBPP molecules are observed. These molecules are immobilized on the surface with a particular orientation with respect to the crystallographic directions of the Cu(110) surface and do not form supramolecular aggregates up to full monolayer coverage. In contrast, a chiral supramolecular structure is formed on the Cu(110)-(2×1)O surface, which is stabilized by van der Waals interactions between the tert-butyl groups of neighboring molecules. These findings are explained by weakened molecule-substrate interactions on the Cu(110)-(2×1)O surface relative to the bare Cu(110) surface. By comparison with the corresponding results of Cu-tetrakis(3,5-di-tert-butyl)phenylporphyrin (CuTTBPP) on Cu(110) and Cu(110)-(2×1)O surfaces, we find that the 2HTTBPP molecules can self-metalate on both surfaces with copper atoms from the substrate at room temperature (RT). The possible origins of the self-metalation reaction at RT are discussed. Finally, peculiar irreversible temperature-dependent switching of the intramolecular conformations of the investigated molecules on the Cu(110) surface was observed and interpreted.

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Surface-Mediatedin SituMetalation of Porphyrins at the Solid–Vacuum Interface

2015

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The investigation of porphyrin derivatives at the solid-vacuum interface has become a vivid research field with the prospect to tailor functional molecular architectures and as prototype examples to study the fundamental properties of porphyrin derivatives in regard to their vital role in many natural processes. The functional properties of the porphyrin derivatives are mainly determined by the central metal atom. Thus, the recent exploration of the surface-confined in situ metalation of porphyrins is an important step toward the realization of molecule-based functional devices. The corresponding metalation reaction of free base porphyrin derivatives can be conveniently realized in situ in ultrahigh vacuum by post- or predeposition of metal atoms or directly with substrate atoms in the so-called self-metalation. Moderate heating above room temperature (RT) might be necessary either to realize the transport of the metal to the porphyrin via diffusion or to overcome an activation barrier determined by the redox reaction itself. Surface science techniques like scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy (XPS), and temperature-programmed desorption (TPD) are powerful tools to scrutinize the reaction and give valuable insights into the metalation process. For example, the completed metalation can be reflected in an enhanced apparent height of the corresponding porphyrin in STM or can be evidenced by characteristic changes in the N 1s region in XPS. These signatures allow monitoring of the progress of the metalation, and it was found that the reaction generally proceeds with very high yield. Surface diffusion of the coadsorbed metal atoms mediates the reaction and is crucial for the high yields of the corresponding reactions with pre- and postadsorbed metals. It was also demonstrated that the completed metalation can indeed significantly alter the adsorption behavior and the electronic properties and thus the functionality of the porphyrin molecules. These alterations can be used to monitor the kinetics of a particular porphyrin self-metalation reaction by STM and to estimate the activation barrier for that reaction based on isothermal measurements at different temperatures. Also TPD measurements of the H2 and D2 signals allow for the determination of corresponding activation energies for the metalation of free base porphyrins and their deuterized analogues. Gas phase DFT calculations of the metalation of the "bare" free base porphyrin macrocycle identify intermediate reaction steps with the transfer of the first hydrogen atom to the metal center being the main barrier to overcome. The values from these calculations are in fair agreement with experimentally determined ones. However, TPD based results indicate that exchanges of deuterium and hydrogen between the central nitrogen and the surface occur, which indicate an active role of the surface and challenge the findings from gas phase DFT. The in situ metalation of porphyrins at the solid-vacuum interface is established as a novel and conveni...

show abstract

Role of the Anchored Groups in the Bonding and Self-Organization of Macrocycles: Carboxylic versus Pyrrole Groups

Cited by 8 publications

References 61 publications

Surface chemistry of porphyrins and phthalocyanines

Surface chemistry of porphyrins and phthalocyanines

2H‐Tetrakis(3,5‐di‐tert‐butyl)phenylporphyrin on a Cu(110) Surface: Room‐Temperature Self‐Metalation and Surface‐Reconstruction‐Facilitated Self‐Assembly

Surface-Mediatedin SituMetalation of Porphyrins at the Solid–Vacuum Interface

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