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Publications

Publications
Principal original articles, reviews, chapters and books published by our group
Publications 2020

2020

Insights into the mechanism of the formation of noble metal nanoparticles by in situ NMR spectroscopy

J. M. Mateo, A. de la Hoz, L. Uson, M. Arruebo, V. Sebastian, M. V. Gomez

Nanoscale Adv. Manuscript ID: NA-ART-02-2020-000159.R3

DOI:

High-resolution solution Nuclear Magnetic Resonance (NMR) spectroscopy has been used to gain insights into the mechanism of formation of gold, platinum and gold-platinum alloyed nanoparticles using metal precursors and tetrakis(hydroxymethyl)phosphonium chloride (THPC) as starting materials. THPC is widely used in nanochemistry as reductant and stabilizer of nanoparticles, however the identity of the specie responsible for each role is unknown. The multinuclear study of the reaction media by NMR spectroscopy allowed us to elucidate the structure of all the compounds that participate in the transformation from the metal salt precursor to the reduced metal that forms the nanoparticle, thus clarifying the controversy found in the literature regarding the formation of THPC-based compounds. The progress of the reaction was monitored from the initial moments of the synthesis to the end of the reaction and after long periods of time. Insights into the dual role of THPC were gained, identifying methanol as the actual reducing agent, and tris(hydroxymethyl)phosphine oxide (THPO) as the real stabilizing agent. Finally, the different stabilities of gold and platinum nanoparticles can be attributed to the different catalytic activity of the metals.

Formation of quaternary carbons through Cobalt-catalyzed C(sp3)-C(sp3) Negishi cross-coupling

 

J. AlcazarE. PalaoE. LopezA. de la HozA. Diaz, I. Torres Moya

 

Chem. Commun., 2020,8210-8220

DOI: 10.1039/D0CC02734K

 Formation of all-carbon-substituted quaternary carbons is a key challenge in organic and medicinal chemistry. We report a cobalt-catalyzed C(sp3)-C(sp3) cross-coupling that allows for the introduction of benzyl, heteroalkyl and allyl groups to halo-carbonyl substrates. The cross-coupling reaction is selective for C(sp3)- over C(sp2)-halides, in contrast to most used catalytic metals, and allows access to novel scaffolds of pharmaceutical interest. NMR mechanistic studies suggest the presence of Co(0) complexes as catalytic species.

Molecular adsorption of iminotriazine derivatives on graphene

Slow diffusion co-assembly as an efficient tool to tune colour emission in alkynyl benzoazoles

R. Martín, I. Torres-Moya, B. Donoso, J.R. Carrillo, J.M. González-Domínguez, J. Frontiñan-Rubio, P. Prieto, A. Díaz-Ortiz

Dyes Pigments 2020, 176, 108246.

doi: 10.1016/j.dyepig.2020.108246

We report here the preparation of co-assembled microcrystals by employing an easy, reproducible and costeffective technique, namely slow diffusion. 2H-Benzo[d][1,2,3]triazole and benzo[c][1,2,5]thiadiazole were chosen as host and guest skeletons, respectively. Structural similarities allowed the correct co-assembly of the two structures. The co-assemblies were studied by different techniques that included Raman spectroscopy and Xray diffraction, amongst others. The waveguiding properties and the emission colour of the doped organic microcrystals were also investigated. It was found that changes in the molar ratio of the different doping agents could tune the light emission. Fluorescence microscopy images of the co-assembled microcrystals revealed light colour changes from green to whitish, up to CIE coordinates of (0.370, 0.385). These tunable colour-active materials could be useful in the fields of optoelectronics or lab-on-a-chip for integrated optical circuits at micro-/nanoscale.

Fluorene-Based Donor-Acceptor Copolymers Containing Functionalized Benzotriazole Units: Tunable Emission and their Electrical Properties

I. Torres-Moya, R. Vázquez-Guilló, S. Fernández-Palacios, J. R. Carrillo, Á. Díaz-Ortiz, J. T. López Navarrete, R. Ponce Ortiz, M. C. Ruiz Delgado, R. Mallavia, P. Prieto

Polymers 2020, 12, 256

doi:10.3390/polym12020256

Monomers 4,7-dibromo-2H-benzo[d]1,2,3-triazole (m1) and 4,7-(bis(4-bromophenyl)ethynyl)-2H-benzo[d]1,2,3-triazole (m2) have been synthesized in good yields using di erent procedures. Monomers m1 and m2 have been employed for building new copolymers of fluorene derivatives by a Suzuki reaction under microwave irradiation using the same conditions.
In each case di erent chain lengths have been achieved, while m1 gives rise to polymers for m2 oligomers have been obtained (with a number of monomer units lower than 7). Special interest has been paid to their photophysical properties due to excited state properties of these D-A units alternates, which have been investigated by density functional theory (DFT) calculations using two methods: (i) An oligomer approach and (ii) by periodic boundary conditions (PBC). It is highly remarkable the tunability of the photophysical properties as a function of the di erent monomer functionalization derived from 2H-benzo[d]1,2,3-triazole units. In fact, a strong modulation of the absorption and emission properties have been found by functionalizing the nitrogen N-2 of the benzotriazole units or by elongation of the -conjugated core with the introduction of alkynylphenyl groups. Furthermore, the charge transport properties of these newly synthesized macromolecules have been approached by their implementation in organic field-effect transistors (OFETs) in order to assess their potential as active materials in organic optoelectronics.