Carlos Lodeiro

One-dimensional fluorescent stacking structure based on zinc mixed-complex salt encapsulated within an ‘ice-like’ three-dimensional hydrogen-bonded water network

Self-assembly of the fluorescent mixed-complex salt [Zn(HL)(phen)2][Zn(L)(HL)(phen)]·13H2O (1) [HL = methyllactato(−1) and L = methyllactato(−2)] created an ‘ice-like’ three-dimensional open framework by hydrogen-bonded crystallisation water molecules that encapsulates an infinite stacking chains result of the intercalation of phenanthroline ligands of complex ions.

Overview on modern approaches to speed up protein identification workflows relying on enzymatic cleavage and mass spectrometry-based techniques.

Recent tools addressed to accelerate the different steps of the sample treatment for protein identification in modern workflows are reviewed and critically commented in this manuscript. Heating, microspin columns, ultrasonic energy, high pressure, infrared energy, microwave energy, alternating electric fields and microreactors are outlined as useful tools that can be used to accelerate all or some of the following steps for in-gel or in-liquid based approaches for protein identification: (i) protein dissolution/denaturation, (ii) protein reduction, (iii) protein alkylation and (iv) protein digestion. The advantages and drawbacks, along with the main differences among the different tools are also commented. Future prospects for hyphenation of methods are also discussed. Researchers are informed also in this work regarding the main problems to be found when implementing any of the above mentioned methods.

Corroles as anion chemosensors: exploiting their fluorescence behaviour from solution to solid-supported devices

The reactivity of the new gallium(III) complex of 3-vinyl-5,10,15-tris(pentafluorophenyl)corrole 4, as a diene in Diels–Alder reactions was studied using 1,4-benzoquinone and 1,4-naphthoquinone as dienophiles. In these reactions only the dehydrogenated adducts 5 and 6 were isolated. All the new corrole derivatives 4–6 were fully characterized by elemental analysis, 1H-NMR, 13C-NMR, 19F-NMR, MALDI-TOF-MS, UV-Vis absorption and emission spectroscopy. The sensing ability of compounds 4–6 and of their precursors 1–3 was studied in solution towards the spherical halide ions F−, Cl−, Br−, I−, the linear anion CN− and the bulky anions CH3COO− and H2PO4−. This study was also realized in gas-phase with the anions F− and CN−. A red-shift in the absorption spectra and an enhancement in the emission intensity were observed, with compounds 1, 3 and 5 being strongly sensitive to fluoride. The highest association constant was obtained for 1 with F−, being able to quantify 0.69 ppm of this anion. On the other hand, compounds 1 and 2 present a high sensitivity towards cyanide anions, producing a red-shift in the absorption and emission spectra and an increase in the emission intensity, being able to quantify a minimal amount of 1.43 ppm. Moreover, compounds 1 and 5 were used to prepare two low-cost solid polymers, based on polymethylmethacrylate (PMMA) and polyacrylamide, the last one being very promising since it is able to detect ca. 70.0 ppb of CN− in water. Compounds 2a and 5 were also tested in the presence of 4,4′-bipyridine, caffeine and nicotine and compound 2a proved to be very sensitive to 4,4′-bipyridine, while compound 5 was really effective for detecting caffeine and nicotine.

Synthesis and characterisation of four novel NxOy-Schiff-base macrocyclic ligands and their metal complexes

Macrocyclic Schiff-bases, L1 and L2, and bis-macrocyclic ligands, L3 and L4, have been prepared by [1 + 1] and [2 + 1] cyclocondensation of 1,7-bis(2′-formylphenyl)-1,4,7-trioxaheptane or 2,6-bis(2-formylphenoxymethyl)pyridine with 2,6-bis(o-aminophenoxymethyl)pyridine or 1,2,4,5-tetraaminebenzene · 4HCl, respectively. The related YIII, MII (M=Co, Ni, Zn, Cd or Pb) and LnIII nitrate or perchlorate complexes have been synthesised following a template procedure, demonstrating the effectiveness of these metal ions to promote the assembly of these four symmetric Schiff-base macrocycles. The complexes were characterised by elemental analyses, molar conductivity, mass spectrometry, i.r., u.v.–vis, and 1H-n.m.r spectroscopy.

Synthesis, Characterization and Metal Ion Detection of Novel Fluoroionophores Based on Heterocyclic Substituted Alanines

The synthesis of new fluorescent probes containing the thiophene and benzoxazole moieties combined with an alanine residue is described. The resulting highly fluorescent heterocyclic alanine derivatives respond via a quenching effect, with paramagnetic Cu(II) and Ni(II) metal ions and with diamagnetic Hg(II), as shown by the absorption and steady-state fluorescence spectroscopy studies. The formation of mononuclear or dinuclear metal complexes was postulated based on the presence of the free carboxylic acid as binding site and also with the interaction with the donor atoms in the chromophore. Interaction with other important biological metal ions such as Zn(II), Ca(II) and Na(I) was also explored.

Bioinspired Systems for Metal-Ion Sensing: New Emissive Peptide Probes Based on Benzo(d)oxazole Derivatives and Their Gold and Silica Nanoparticles )

Seven new bioinspired chemosensors (2-4 and 7-10) based on fluorescent peptides were synthesized and characterized by elemental analysis, (1)H and (13)C NMR, melting point, matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and IR and UV-vis absorption and emission spectroscopy. The interaction with transition- and post-transition-metal ions (Cu(2+), Ni(2+), Ag(+), Zn(2+), Cd(2+), Hg(2+), Pb(2+), and Fe(3+)) has been explored by absorption and fluorescence emission spectroscopy and MALDI-TOF-MS. The reported fluorescent peptide systems, introducing biological molecules in the skeleton of the probes, enhance their sensitivity and confer them strong potential for applications in biological fields. Gold and silica nanoparticles functionalized with these peptides were also obtained. All nanoparticles were characterized by dynamic light scattering, transmission electron microscopy, and UV-vis absorption and fluorescence spectroscopy. Stable gold nanoparticles (diameter 2-10 nm) bearing ligands 1 and 4 were obtained by common reductive synthesis. Commercial silica nanoparticles were decorated at their surface using compounds 8-10, linked through a silane spacer. The same chemosensors were also taken into aqueous solutions through their dispersion in the outer layer of silica core/poly(ethylene glycol) shell nanoparticles. In both cases, these complex nanoarchitectures behaved as new sensitive materials for Ag(+) and Hg(2+) in water. The possibility of using these species in this solvent is particularly valuable because the impact on human health of heavy- and transition-metal-ion pollution is very severe, and all analytical and diagnostics investigations involve a water environment.

Latest developments in sample treatment for 18O-isotopic labeling for proteomics mass spectrometry-based approaches: a critical review.

Nowadays isotopic (18)O-labeling of peptides has recalled the attention of researchers due to its simplicity of application and high versatility for proteomics studies. Protein quantification, differential peptide mass mapping, studies regarding proteins overexpressed or underexpressed, or the searching of biomarkers can be accomplished by using (18)O-labeling. In this critical review we comment on the different ways in which (18)O-labeling can be done, highlighting the key parameters of the different sample treatments to obtain a reliable and reproducible labeling. In addition we describe and compare the latest improvement in terms of sample treatment that allows to reduce the handling and to increase the throughput for this sample treatment. Finally, we hypothesize on the future trends of these methods under the light of the new technological advances to speed protein cleavage.

Synthesis and Characterization of Some Metal Complexes with New Nitrogen–Oxygen Donor Macrocyclic Ligands – X‐ray Crystal Structures of a 26‐Membered Reduced Monoprotonated Macrocycle and a 20‐Membered Pendant‐Arm Schiff‐Base Macrocyclic Cadmium(II) Complex

New series of macrocyclic Schiff-base lanthanide(III), yttrium(III), and cadmium(II) complexes, [M(1)]Xn (X = NO, M = Y, Ln = La–Yb except Pm and Dy; X = ClO, M = Cd, La, Ce, Pr, Sm, Gd, or Er) and [M(3)]Xn (X = NO, M = Dy; X = ClO, M = Er and Cd), have been prepared by cyclocondensation of O1,O7-bis(2-formylphenyl)-1,4,7-trioxaheptane with O1,O7-bis(2-aninyl)-1,4,7-trioxaheptane (1) or tris(2-aminoethyl)amine (3) in the presence of the appropriate metal salt as a template agent. The Schiff-base macrocycles 1 and 3 are also formed in the absence of a metal ion. Treatment of 1 with NaBH4 in methanol gives the diamine macrocycle 2. The reactions of LnIII, CdII, and YIII ions with 2 have also been investigated. The crystal structures of the monoprotonated ligand 2 and of the complex [Cd(3)](ClO4)2 have been determined by X-ray diffraction analysis.

Zinc and cadmium complexes with an achiral symmetric helicand. Crystal structure of an enantiomerically pure Λ-Zn(II) monohelicate

Zn(II) and Cd(II) complexes with an N-tosyl substituted N4-donor Schiff base, containing a 2-propanol residue as spacer, have been prepared. The X-ray crystal structure of the monohelicate Λ-Zn(OHPTs)·H2O [H2OHPTs: N,N′-bis(2-tosylaminobenzylidene)-1,3-diamino-2-propanol] has been solved. The Zn(II) ion assumes a distorted tetrahedral coordination geometry, involving the four donor N atoms of the bisdeprotonated ligand. Strong (O–H⋯O) hydrogen bonds between neighbouring complex and lattice water molecules lead to intricate intermolecular interactions that seem to drive the crystal packing. This Zn(II) complex shows an intense blue fluorescence in solution (λ = 430 nm, ϕ = 0.14), which is also observed in the solid state (λ = 490 nm). Cd(OHPTs)·4H2O, although at a lower level (ϕ = 0.08), is also luminescent (λ = 430 nm) in acetonitrile solution.

Complexation of aluminum(III) by anthocyanins and synthetic flavylium salts A source for blue and purple color

Abstract The single crystal structure of two synthetic flavylium salts possessing a catechol unit in position 7 and 8, (7,8-dihydroxy-4-methylflavylium,7,8-dihydroxyflavylium) is shown. The formation of aluminium complexes with these ligands as well as with the natural anthocyanin, cyanin, and the deoxyanthocyanidin, luteolinidin, both bearing a cathecol unit in position 3′ and 4′, is described. Complexation with Al3+ stabilizes the blue ionised quinoidal base avoiding its degradation by reaction with oxygen. The simple model developed to describe the complexation, indicates a metal ligand stoichiometry of 1:1. The complexation constants lie between 5.5×106