0000000001301718
AUTHOR
Alberto Credi
Towards Organization of Molecular Machines at Interfaces. Langmuir Films and Langmuir-Blodgett Multilayers of an Acid-Base Switchable Rotaxane
In this context we investigated, for the first time, the organi-zation of a non-amphiphilic tricationic switchable rotaxaneand its dumbbell-shaped component into Langmuir films andLangmuir–Blodgett (LB) multilayers by using a cospreadingstrategy. The Langmuir films have been characterized by sur-face pressure–area (
Ion-Pairing Effects in the Self-Assembly of a Fluorescent Pseudorotaxane
Herein we report on the self-assembly, in a low polarity solvent, of a pseudorotaxane species comprising binaphthyl-26-crown-8 (BN26C8) as the macrocyclic host and anthracenyl-benzylammonium as the threadlike positively charged guest (ABH+). Absorption and luminescence data reveal a very efficient energy transfer process occurring from the binaphthyl to the anthracene singlet excited states. The self-assembly is highly dependent on the nature of the counteranion confirming the crucial role played by it in the competition between the self-assembly process and the formation of ion pairs (ABH+X-). This behavior can be readily evidenced in dilute solutions from the analysis of the luminescence …
Modulation of the solubility of luminescent semiconductor nanocrystals through facile surface functionalization
The solubility of luminescent quantum dots in solvents from hexane to water can be finely tuned by the choice of the countercations associated with carboxylate residues present on the nanocrystal surface. The resulting nanocrystals exhibit long term colloidal and chemical stability and maintain their photophysical properties.
Autonomous artificial nanomotor powered by sunlight
Light excitation powers the reversible shuttling movement of the ring component of a rotaxane between two stations located at a 1.3-nm distance on its dumbbell-shaped component. The photoinduced shuttling movement, which occurs in solution, is based on a “four-stroke” synchronized sequence of electronic and nuclear processes. At room temperature the deactivation time of the high-energy charge-transfer state obtained by light excitation is ≈10 μs, and the time period required for the ring-displacement process is on the order of 100 μs. The rotaxane behaves as an autonomous linear motor and operates with a quantum efficiency up to ≈12%. The investigated system is a unique example of an artif…
Synthesis of Densely Packaged, Ultrasmall Pt02Clusters within a Thioether-Functionalized MOF: Catalytic Activity in Industrial Reactions at Low Temperature
The gram-scale synthesis, stabilization, and characterization of well-defined ultrasmall subnanometric catalytic clusters on solids is a challenge. The chemical synthesis and X-ray snapshots of Pt02 clusters, homogenously distributed and densely packaged within the channels of a metal-organic framework, is presented. This hybrid material catalyzes efficiently, and even more importantly from an economic and environmental viewpoint, at low temperature (25 to 140 °C), energetically costly industrial reactions in the gas phase such as HCN production, CO2 methanation, and alkene hydrogenations. These results open the way for the design of precisely defined catalytically active ultrasmall metal c…
A Comparison of Shuttling Mechanisms in Two Constitutionally Isomeric Bistable Rotaxane-Based Sunlight-Powered Nanomotors
To find out how best to optimize shuttling of the macrocycle in a particular class of photochemically driven molecular abacus, which has the molecular structure of BR-I6+ in its Mark I prototype (Ashton et al., Chem. Eur. J. 2000, 6, 3558), we have synthesized and characterized a Mark II version of this kind of two-station rotaxane comprised of six molecular modules, namely (a) a bisparaphenylene[34]crown-10 electron donor macrocycle M and its dumbbell-shaped component which contains (b) a Ru(ii)-polypyridine photoactive unit P2+ as one of its stoppers, (c) a p-terphenyl-type ring system as a rigid spacer S, (d) 4,4′-bipyridinium (A12+) and (e) 3,3′-dimethyl-4,4′-bipyridinium (A22+) electr…
Controlling Multivalent Interactions in Triply-Threaded Two-Component Superbundles
We have investigated the (1)H NMR spectra, the absorption spectra, the fluorescence spectra and decays, and the electrochemical properties of i). a tritopic receptor in which three benzo[24]crown-8 macrorings are fused onto a triphenylene core, ii). a trifurcated trication wherein three dibenzylammonium ions are linked 1,3,5 to a central benzenoid core, and iii). their 1:1 adduct which constitutes a triply-threaded, two-component supramolecular bundle. X-Ray crystallography has established the precise geometry of this paucivalent recognition motif in the solid state. In addition to [N(+)-H...O] hydrogen bonding and [C-H...O] interactions between the NH(2) (+) centers on the three dibenzylam…
CCDC 1587822: Experimental Crystal Structure Determination
Related Article: Marta Mon, Miguel A. Rivero-Crespo, Jesffls Ferrando-Soria, Alejandro Vidal-Moya, Mercedes Boronat, Antonio Leyva-Pérez, Avelino Corma, Juan C. Hernandez-Garrido, Miguel Lopez-Haro, José J. Calvino, Giulio Ragazzon, Alberto Credi, Donatella Armentano, Emilio Pardo|2018|Angew.Chem.,Int.Ed.|57|6186|doi:10.1002/anie.201801957
CSD 1409698: Experimental Crystal Structure Determination
Related Article: Marta Mon, Miguel A. Rivero-Crespo, Jesffls Ferrando-Soria, Alejandro Vidal-Moya, Mercedes Boronat, Antonio Leyva-Pérez, Avelino Corma, Juan C. Hernandez-Garrido, Miguel Lopez-Haro, José J. Calvino, Giulio Ragazzon, Alberto Credi, Donatella Armentano, Emilio Pardo|2018|Angew.Chem.,Int.Ed.|57|6186|doi:10.1002/anie.201801957
CCDC 1587821: Experimental Crystal Structure Determination
Related Article: Marta Mon, Miguel A. Rivero-Crespo, Jesffls Ferrando-Soria, Alejandro Vidal-Moya, Mercedes Boronat, Antonio Leyva-Pérez, Avelino Corma, Juan C. Hernandez-Garrido, Miguel Lopez-Haro, José J. Calvino, Giulio Ragazzon, Alberto Credi, Donatella Armentano, Emilio Pardo|2018|Angew.Chem.,Int.Ed.|57|6186|doi:10.1002/anie.201801957