A palladium-hinged organometallic square with a perfect-sized cavity for the encapsulation of three heteroguests

This is a pre-print of an article published in Chemical Communications. The final authenticated version is available online at: https://doi.org/10.1039/C9CC08595E.A nanometer-sized tetrapalladium metallosquare with a pyrene-bisimidazolylidene ligand was found to display a perfect-sized cavity for the encapsulation of three heteroguests, enabling the formation of quintuple D–A–D–A–D stacks. The encapsulating properties of the metallosquare are clearly determined by the presence of the pyrene panels, which endow the metallosquare with a three-dimensional shape, and also behave as effective antennae for π-stacking interactions

Cuestiones de Tema 2. Compuestos con ligandos - σ

I61:Química Organometàl.lic

Polyaromatic N-heterocyclic carbene ligands and π-stacking. Catalytic consequences

In the course of our most recent research, we demonstrated how homogeneous catalysts with polyaromatic functionalities possess properties that clearly differ from those shown by analogues lacking these polyaromatic systems. The differences arise from the ability of the polyaromatic groups to afford non-covalent interactions with aromatic molecules, which can either be substrates in a homogeneous catalysed reaction, or the same catalysts to afford self-assembled systems. This article summarizes all our efforts toward understanding the fundamental effects of p-stacking interactions in homogenous catalysis, particularly in those cases where catalysts bearing polyaromatic functionalities are used. The study reveals several important implications regarding the influence of ligand–ligand interactions, ligand–additive interactions, and ligand–substrate interactions, in the performance of the catalysts used. In particular, the electronic properties of ligands with fused polyconjugated systems, are modified if molecules with p-stacking abilities are added, via a ligand–additive interaction. Also, the kinetics of the reactions in which aromatic substrates and catalysts with polyaromatic ligands are used, are strongly influenced by the self-association of the catalysts and by the non-covalent interaction between the catalyst and the aromatic substrates. The nature and the magnitude of these supramolecular interactions were unveiled by using host–guest chemistry methods applied to organometallic catalysis. Finally, noncovalent interactions afford a very convenient approach for the immobilization of catalysts decorated with polyaromatic systems onto the surfaces of graphene derivatives, hence affording an easy yet extremely effective way to support catalysts and facilitate recycling. The results given have fundamental implications in the design of future catalysts containing rigid polyaromatic systems, and may inspire future researchers in the design of improved homogeneous catalysts, by taking into account that the activities of the metal complexes are strongly modified by supramolecular interactions.Financial support from the ‘Ministerio de Economía y Competitividad’ MINECO of Spain (CTQ2014-51999-P) and the Universitat Jaume I (P11B2014-02

Cuestiones del TEMA 3: Compuestos con ligandos dadores-pi

I61:Química Organometàl.lic

Cuestiones de Tema 2. Compuestos con ligandos - σ ( cuestiones adicionales)

I61:Química Organometàl.lic

Shape-Adaptability and Redox-Switching Properties of a Di-Gold Metallotweezer

The use of a carbazolyl-connected di-gold(I) metallotweezer for the encapsulation of several electron-poor organic substrates, and a planar Au(III) complex containing a CNC pincer ligand, is described. The binding affinity of the receptor depends on the electron-deficient character of the planar guest, with larger association constants found for the more electron-poor guests. The X-ray diffraction molecular structures of two host:guest adducts show that the host approaches its arms in order to facilitate the optimum interaction with the surface of the planar guests, in a clear example of an guest-induced fit conformational arrangement. The electrochemical studies of the encapsulation of N,N’-dimethyl-naphthalenetetracarboxy diimide (NTCDI) show that the redox active guest is released from the receptor upon one electron reduction, thus constituting an example of redox-switchable binding.Funding for open access charge: CRUE-Universitat Jaume

Dimensional Matching versus Induced‐Fit Distortions: Binding Affinities of Planar and Curved Polyaromatic Hydrocarbons with a Tetragold Metallorectangle

This is the peer reviewed version of the following article: Dimensional Matching versus Induced‐Fit Distortions: Binding Affinities of Planar and Curved Polyaromatic Hydrocarbons with a Tetragold Metallorectangle, which has been published in final form at https://doi.org/10.1002/anie.201915401. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.A tetragold(I) rectangle‐like metallocage containing two pyrene‐bis‐imidazolylidene ligands and two carbazolyl‐bis‐alkynyl linkers is used for the encapsulation of a series of polycyclic aromatic hydrocarbons (PAHs), including corannulene. The binding affinities obtained for the encapsulation of the planar PAHs guests in CD2Cl2 are found to exponentially increase with the number of π‐electrons of the guest (1.3 > logK >6.6). For the bowl‐shaped molecule of corannulene, the association constant is much lower than the expected one according to its number of electrons. The molecular structure of the host–guest complex formed with corannulene shows that the molecule of the guest is compressed, while the host is expanded, thus showing an interesting case of artificial mutual induced‐fit arrangement

Photocatalytic Properties of a Palladium Metallosquare with Encapsulated Fullerenes via Singlet Oxygen Generation

Singlet oxygen has recently attracted a great deal of attention due to its strong oxidizing properties, which makes it useful in organic synthesis and biological studies. However, the photosensitizers that are required for singlet oxygen generation remain inadequate due to their often low thermal and photochemical stabilities. Here we describe the use of a palladium-conjoined metallosquare with encapsulated fullerenes (C60 or C70), which behaves as an efficient and photochemically stable singlet oxygen photosensitizer. The metallocage with the encapsulated fullerenes can oxidize a series of cyclic and acyclic alkenes at room temperature via visible light-induced singlet oxygen generation, using oxygen molecules in air at atmospheric pressure. These reactions take advantage of the excellent spin-converting properties of fullerenes, which make them excellent agents for singlet oxygen production