María J. Romero

Conformational rearrangement of 2,6-bis(1-salicyloylhydrazonoethyl)pyridine (H4daps) on complexation. Synthesis and X-ray characterisation of H4daps and its copper helicate complex [Cu(H2daps)(H2O)]2·2CH3CN

The copper complex of 2,6-bis(1-salicyloylhydrazonoethyl)pyridine, H4daps, has been prepared by an electrochemical procedure and characterised by elemental analysis, IR, FAB mass spectroscopy, ΛM, magnetic susceptibility measurements and EPR studies. The molecular structures of the ligand H4daps (1) and its copper complex [Cu(H2daps)(H2O)]2·2CH3CN (3) have been determined by X-ray diffraction studies. The ligand shows in the solid state a syn-open conformation that allows it to act as a binucleating ligand, after a conformational change, as is shown by the study of the copper dihelicate 3. This compound contains the dianionic ligand [H2daps]2− in an anti-open conformation. The comparative study of this complex, with others previously reported, allows us to confirm that the conformational rearrangement undergone by H4daps upon complexation depends strongly on the metal nature and its stereochemical preferences.

Pentadentate thiosemicarbazones as versatile chelating systems. A comparative structural study of their metallic complexes

We have prepared some transition and post-transition metal complexes derived from the pentadentate thiosemicarbazone ligand bis(4-N-ethylthiosemicarbazone)-2,6-diacetylpyridine H(2)L(Et), by both chemical and electrochemical procedures. The complexes have been synthesised and fully characterised, including the crystal structures for the ligand H(2)L(Et) and its manganese, cadmium and lead complexes. We have also performed multinuclear (109)Ag, (113)Cd, (119)Sn and (207)Pb studies for silver, cadmium, tin and lead compounds, respectively. Moreover we present here a comparative study on the different structures found for pentadentate thiosemicarbazonate complexes, trying to check the influence of different factors, such as experimental procedure, size of metal, structure of the ligand, and metal oxidation state, on the final structure of the complex formed. Our aim is gaining a better insight into the coordination trends of pentadentate thiosemicarbazone ligands.

Coordinative trends of a tridentate thiosemicarbazone ligand: synthesis, characterization, luminescence studies and desulfurization processes

The coordinative chemistry of the tridentate thiosemicarbazone ligand 2-pyridinecarboxaldehyde 4-N-ethylthiosemicarbazone (HL(Et)) has been explored by using an electrochemical methodology. All the complexes have been characterized using analytical and spectroscopic techniques. In the case of copper we have isolated two different complexes, with Cu(L(Et))(2).4H(2)O (6) and [Cu(2)(L(Et))(2)(SO(4))] (7) formulae. The sulfate group coordinated to the copper atoms in was probably released to the media as a consequence of a desulfurization process. Single X-ray crystallography has been carried out for the ligand HL(Et) and the complexes , [Ag(6)(L(Et))(6)].CH(3)CN (9) and [Pb(L(Et))(2)] (2). The copper(ii) complex is a dimer compound in which two antiparallel monodeprotonated ligands are coordinated to two copper centres by establishment of mu(2)-thiolate bridges and the additional coordination of a sulfate group bridging the two metal atoms. The silver complex is an unusual hexanuclear cluster compound with a wheel-type conformation, while the lead complex is a monomer which exhibits the lone pair effect. A structural comparative study of the electrochemically obtained complexes derived from HL(X) ligands (X= Me, Et and Ph) have been performed. Finally, the solution behaviour of the complexes was checked by NMR, UV and fluorescence studies.

Use of chalazion forceps to ease biopsy of minor salivary glands.

INTRODUCTION Pathologic features of minor salivary glands are one of the six criteria for classification of Sjogren syndrome. The presence of one or more foci of 50 or more mononuclear cells within 4 mm of gland tissue is considered supportive of this diagnosis.1 Amyloidosis is diagnosed by demonstrating the presence of amyloid protein in the affected organ. It is possible to take biopsies of affected tissues from kidney, liver, or rectum. However, it causes far less morbidity to obtain a sample of tissue from minor salivary glands as a first step toward diagnosis of amyloidosis.2 Chalazion forceps (Moria Dugast, Paris, France) are used by ophthalmologists during chalazion excisions, but its particular design also makes the device useful for taking biopsies from mobile or oral tissues.3

Unprecedent isolation of a mixture of conformational and linkage isomers in a thiosemicarbazone cobalt mesocate.

A cobalt(II) thiosemicarbazonate mesocate has been structurally characterized as an unexpected mixture of conformational and linkage isomers. Moreover, we have shown that the absence of a nitrogen atom in the spacer of the helicand ligand H(2)L(a), enables the assembly of an achiral mesohelical complex in the case of Co(II) ions.

Novel Manganese(III) Complexes with the Schiff Base N,N′‐(1,2‐Phenylene)‐bis(3‐Hydroxysalicylidenimine)

Four novel manganese(III) complexes have been prepared using the tetradentate ONNO symmetrical Schiff base N,N′‐(1,2‐phenylene)‐bis(3‐hydroxysalicylidenimine) H4L and employing different manganese(II) and manganese(III) starting salts (chloride, acetate, acetylacetonate and perchlorate). These complexes were thoroughly characterised by elemental analysis, ES mass spectrometry, infrared and paramagnetic 1H NMR spectroscopies, magnetic susceptibility measurements and molar conductivities. Electrochemical studies by cyclic and normal pulse voltammetry were also performed. All complexes obtained are manganese(III) ones, in which the anions belonging to the starting salts have diverse coordinating tendencies; this fact seems to determine the nuclearity of the final complexes, with empirical formulae [Mn(H2L)(H2O)2]Cl(H2O)3 1, [Mn(H2L)(OAc)](H2O) 2, [Mn(H2L)(acac)](H2O)3 3, and [Mn(H2L)(H2O)(CH3OH)](ClO4) 4. The X‐ray crystal structure of H4L Schiff base has been determined.

An unusual assembled Pb(II) meso-helicate that shows the inert pair effect

A dinuclear Pb(ii) mesocate has been prepared with an unprecedented four-coordinated kernel in which the Pb(ii) lone pair is stereochemically active. This is the first time that this effect has been observed in a supramolecular Pb(ii) helicate or meso-helicate.

“The Golden Method”: Electrochemical Synthesis Is an Efficient Route to Gold Complexes

Gold compounds to be obtained by the direct electrochemical oxidation of a noble metal are reported. This achievement provides an alternative procedure to obtaining neutral gold compounds with potential medical or catalytic applications.

Synthesis and structural characterization of a novel amine-bis(phenolate)ligand

The substituted amine-bis(phenol) compound N,N-bis-(4,5-dimethyl-2-hydroxybenzyl)-N(2-pyridylethyl)amine (H2L) was prepared through a Mannich reaction utilizing two equivalents of a substituted phenol, two equivalents of formaldehyde and a single equivalent of a secondary amine. The organic compound, which may act as a tripodal ligand in coordination complexes, has been characterized by elemental analysis, IR, and 1H and 13C NMR spectroscopies, mass spectrometry (ES) and X ray diffraction spectroscopy.

Effect of the Metal Ion on the Enantioselectivity and Linkage Isomerization of Thiosemicarbazone Helicates

The effect of the metal ion and ligand design on the enantioselectivity and linkage isomerization of neutral cobalt and zinc bisthiosemicarbazone metallohelicates has been investigated in this work. The electrochemical synthesis has afforded the enantioselective formation of chirally pure cobalt helicates, and the ΛΛ isomer of a single enantiomer has been crystallized as only product for the cobalt methyl-substituted thiosemicarbazone helicate. Interestingly linkage isomers have been formed from zinc ethyl-substituted thiosemicarbazone helicate enantiomers for the first time. The co-existence of these isomers has been evaluated from the point of view of both experimental results and computational calculations.