Sara P. Morcillo

Mild Method for the Selective Esterification of Carboxylic Acids Based on the Garegg−Samuelsson Reaction

A mild method for the selective esterification of primary alcohols is described. The use of different phosphines, I(2), and imidazole allows the selective esterification of a wide variety of acids with excellent results. The generation of a bulky phosphonium-carboxylate salt as intermediate could justify the selectivity observed in this process. Additionally, amides also can be synthesized with use of this method.

Recent applications of Cp2TiCl in natural product synthesis

This review highlights the recent applications of titanocene(III) complexes in the field of natural product synthesis from the seminal precedents to the development of modern catalytic methods. The power of the titanocene(III)-based approaches is demonstrated by the straightforward syntheses of many natural products from readily available starting materials.

Ti(III)-catalyzed cyclizations of ketoepoxypolyprenes: control over the number of rings and unexpected stereoselectivities.

We describe a new strategy to control the number of cyclization steps in bioinspired radical (poly)cyclizations involving epoxypolyenes containing keto units positioned along the polyene chain. This approach provides an unprecedentedly straightforward access to natural terpenoids with pendant unsaturated side chains. Additionally, in the case of bi- and tricyclizations, decalins with cis stereochemistry have been obtained as a consequence of the presence of the ketone. The preferential formation of cis-fused adducts was rationalized using DFT calculations. This result is completely unprecedented in biomimetic cyclizations and permits the access to natural terpenoids with this stereochemistry, as well as to non-natural analogues.

Toward Multiple Conductance Pathways with Heterocycle-Based Oligo(phenyleneethynylene) Derivatives

In this paper, we have systematically studied how the replacement of a benzene ring by a heterocyclic compound in oligo(phenyleneethynylene) (OPE) derivatives affects the conductance of a molecular wire using the scanning tunneling microscope-based break junction technique. We describe for the first time how OPE derivatives with a central pyrimidine ring can efficiently link to the gold electrode by two pathways presenting two different conductance G values. We have demonstrated that this effect is associated with the presence of two efficient conductive pathways of different length: the conventional end-to-end configuration, and another with one of the electrodes linked directly to the central ring. This represents one of the few examples in which two defined conductive states can be set up in a single molecule without the aid of an external stimulus. Moreover, we have observed that the conductance through the full length of the heterocycle-based OPEs is basically unaffected by the presence of the heterocycle. All these results and the simplicity of the proposed molecules push forward the development of compounds with multiple conductance pathways, which would be a breakthrough in the field of molecular electronics.

Development of a new dual polarity and viscosity probe based on the foldamer concept.

Small molecular probes able to act as sensors are of enormous interest thanks to their multiple applications. Here, we report on the development of a novel supramolecular dual viscosity and polarity probe based on the foldamer concept, which increases the resolution limits of traditional probes at low viscosity values (0-4 mPa·s). The applicability of this new probe has been tested with a supramolecular organogel.

Pyrene-Containing ortho-Oligo(phenylene)ethynylene Foldamer as a Ratiometric Probe Based on Circularly Polarized Luminescence

In this manuscript, we report the first synthesis of an organic monomolecular emitter, which behaves as a circularly polarized luminescence (CPL)-based ratiometric probe. The enantiopure helical ortho-oligo(phenylene)ethynylene (o-OPE) core has been prepared by a new and efficient macrocyclization reaction. The combination of such o-OPE helical skeleton and a pyrene couple leads to two different CPL emission features in a single structure whose ratio linearly responds to silver(I) concentration.

Thermally Driven Nanofuses Based on Organometallic Rotors

Molecular design of chromium arenes are theoretically studied as a model for the development of novel thermally-driven molecular fuses. This study correlates the switching event with a partial disconnection of the molecule from the metallic electrode mediated by changes in the conformational states of the molecule directed by external stimuli. Moreover, the reversibility of the process (the reconnection to the metallic electrode) is also considered for these systems when a reversal voltage pulse (reset) is applied. The energetic requirements of the on and off states are correlated with temperature through the Arrhenius equation. To carry out this study we performed density functional theory (DFT) calculations.