Jorge Escorihuela

Nickel complexes from α-amino amides as efficient catalysts for the enantioselective Et2Zn addition to benzaldehyde

Abstract Ni2+ complexes derived from simple α-amino amides catalyze very efficiently the addition of Et2Zn to benzaldehyde, giving (S)-1-phenylethanol as the major isomer in most cases (94% yield, 97% ee for R=Bn). The nature of the substituent on the amide nitrogen atom seems to play a key role in determining the asymmetric induction observed.

Dual-Polarization Interferometry: A Novel Technique To Light up the Nanomolecular World

Nanomolecular World Jorge Escorihuela,† Miguel Ángel Gonzaĺez-Martínez,† Jose ́ Luis Loṕez-Paz,† Rosa Puchades,† Ángel Maquieira,† and David Gimenez-Romero*,‡ †Department of Chemistry, Institute of Molecular Recognition and Technological Development, Universitat Politec̀nica de Valeǹcia, Camino de Vera s/n, 46022 Valeǹcia, Spain ‡Physical Chemistry Department, Faculty of Chemistry, Universitat de Valeǹcia, Avenida Dr. Moliner 50, 46100 Burjassot, Valeǹcia, Spain

Direct Covalent Attachment of DNA Microarrays by Rapid Thiol–Ene “Click” Chemistry

A rapid strategy for the covalent immobilization of DNA onto silicon-based materials using the UV-initiated radical thiol-ene reaction is presented in this study. Following this approach, thiol- and alkene-modified oligonucleotide probes were covalently attached in microarray format, reaching immobilization densities around 6 pmol·cm(-2). The developed methodology presents the advantages of spatially controlled probe anchoring (using a photomask), direct attachment without using cross-linkers (one-pot fashion), and short irradiation times (20 min). Using the described strategy, hybridization efficiencies up to 65% with full complementary strands were reached. The approach was evaluated by scoring single-base pair mismatches with discrimination ratios around 15. Moreover, the efficacy of the proposed DNA detection scheme is further demonstrated through the assay on a genomic target of bacterial Escherichia coli.

Coordination of Cu2+ Ions to C2 Symmetric Pseudopeptides Derived from Valine

The acid-base and coordination properties of a family of pseudopeptidic ligands with C(2) symmetry derived from valine (4a-e) have been studied using a variety of techniques as a model for metal coordination in peptides and proteins. The Cu(2+) cation has been selected for coordination studies, although, for comparison, some results for Zn(2+) are also presented. Good agreement has been obtained between the results obtained by potentiometric titrations, spectroscopic analysis, and mass spectrometry (ESI) studies. These results highlight the potential for the use of ESI MS for characterizing the nature of the complex species formed. Clearly, the Cu(2+) complexes are much more stable than the Zn(2+) complexes. While the role of the aliphatic spacer seems to be very minor in the case of the Zn(2+) complexes, revealing the ability of this cation to accommodate different coordination environments, this role is critical in the case of Cu(2+). Different complexes with 1:1 or 2:2 Cu(2+):L stoichiometries can be formed according to the length of the spacer and the basicity of the media. This is fully illustrated by the resolution of the X-ray structures of two different Cu(2+) complexes corresponding to the ligands containing a spacer with two methylene groups (ligand 4a, complex 6a [Cu(2)(H(-1)L)(2)](ClO(4))(2) with a 2:2 stoichiometry) and a propylene spacer (4b, complex 5b [CuH(-2)L] x CH(3)CH(2)OH with a 1:1 stoichiometry).

Development of oligonucleotide microarrays onto Si-based surfaces via thioether linkage mediated by UV irradiation.

Selective covalent immobilization of thiolated oligonucleotides onto an epoxy-functionalized silicon-substrate can be achieved via light radiation (365 nm). Following this approach, thiol-modified oligonucleotide probes were covalently attached as microarrays, reaching an immobilization density of 2.5 pmol·cm(-2), with a yield of 53%. The developed method presents the advantages of spatially controlled probe anchoring (by means of using a photomask), direct attachment without using cross-linkers, and short irradiation times (10 min). Hybridization efficiencies up to 65%, with full complementary strands, were reached. The approach was evaluated by scoring single nucleotide polymorphisms with a discrimination ratio around 15. Moreover, sensitive and selective detection of bacterial Escherichia coli was demonstrated.

Site-specific immobilization of DNA on silicon surfaces by using the thiol–yne reaction

Covalent immobilization of ssDNA fragments onto silicon-based materials was performed using the thiol-yne reaction. Chemical functionalization provided alkyne groups on the surface where the thiol-modified oligonucleotide probes can be easily photoattached as microarrays, reaching an immobilization density around 30 pmol cm-2. The developed method presents the advantages of spatially controlled probe anchoring (by using a photomask), direct attachment without using cross-linkers, and short irradiation times (20 min). Hybridization efficiencies up to 70%, with full complementary strands, were reached. The approach was evaluated by scoring single nucleotide polymorphisms with a discrimination ratio around 15. Moreover, the potential applicability of the proposed methodology is demonstrated through the specific detection of 20 nM of a genomic target of bacterial Escherichia coli.

Bis(imidazolium) salts derived from amino acids as receptors and transport agents for chloride anions

The binding properties of bis(imidazolium) hosts 1a–c derived from amino acids towards different anions have been studied by 1H NMR titration experiments in 95 : 05 CD3CN : H2O at 303 K, ESI-MS and theoretical calculations. Among this family, the salt 1c showed a strong and high selectivity for chloride anions. Transmembrane chloride transport activity has also been studied for the three bis(imidazolium) based transporters in POPC liposome models, and compound 1a was identified as an active chloride/nitrate exchanger.

A simple peptidomimetic that self-associates on the solid state to form a nanoporous architecture containing chiral π-channels

The crystal structure of a simple peptidomimetic compound, derived from phenylalanine, shows the formation of a nanoporous architecture containing monodimensional π-channels with the aromatic rings as the exclusive components of the chiral channel walls.

Rapid and Complete Surface Modification with Strain-Promoted Oxidation-Controlled Cyclooctyne-1,2-Quinone Cycloaddition (SPOCQ)

Abstract Strain‐promoted oxidation‐controlled cyclooctyne‐1,2‐quinone cycloaddition (SPOCQ) between functionalized bicyclo[6.1.0]non‐4‐yne (BCN) and surface‐bound quinones revealed an unprecedented 100 % conjugation efficiency. In addition, monitoring by direct analysis in real time mass spectrometry (DART‐MS) revealed the underlying kinetics and activation parameters of this immobilization process in dependence on its microenvironment.

Use of Ambient Ionization High-Resolution Mass Spectrometry for the Kinetic Analysis of Organic Surface Reactions

In contrast to homogeneous systems, studying the kinetics of organic reactions on solid surfaces remains a difficult task due to the limited availability of appropriate analysis techniques that are general, high-throughput, and capable of offering quantitative, structural surface information. Here, we demonstrate how direct analysis in real time mass spectrometry (DART-MS) complies with above considerations and can be used for determining interfacial kinetic parameters. The presented approach is based on the use of a MS tag that--in principle--allows application to other reactions. To show the potential of DART-MS, we selected the widely applied strain-promoted alkyne-azide cycloaddition (SPAAC) as a model reaction to elucidate the effects of the nanoenvironment on the interfacial reaction rate.