Víctor M. Jiménez-Pérez

Iron-containing nanomaterials: synthesis, properties, and environmental applications

Available data on the iron-containing nanomaterials are reviewed. Main attention is paid to the following themes: synthetic methods, structures, composition and properties of the nano zerovalent iron (NZVI), and polymorphic forms of iron oxides and FeOOH. Synthetic methods summarized here include a series of physico-chemical methods such as microwave heating, electrodeposition, laser ablation, radiolytical techniques, arc discharge, metal-membrane incorporation, pyrolysis, combustion, reverse micelle and co-deposition routes. We have also included a few “greener” methods. Coated, doped, supported with polymers or inert inorganic materials, core–shell nanostructures, in particular those of iron and its oxides with gold, are discussed. Studies of remediation involving iron-containing nanomaterials are discussed and special attention is paid to the processes of remediation of organic contaminants (chlorine-containing pollutants, benzoic and formic acids, dyes) and inorganic cations (Zn(II), Cu(II), Cd(II) and Pb(II)) and anions (nitrates, bromates, arsenates). Water disinfection (against viruses and bacteria), toxicity and risks of iron nanomaterials application are also examined.

Rigid five-coordinate diorganotin derivatives of oxalic acid diamides, studied by 119Sn-NMR and X-ray structural analysis

Abstract Bis(2-hydroxy-3,5-di- tert -butyl-phenylanilido) oxalic acid reacts with diorganotin dichlorides, R 2 SnCl 2 , in the presence of triethylamine to give the polycyclic bis(diorganotin) derivatives 1 , in which the surroundings of each tin atom correspond to a distorted trigonal bipyramid with one nitrogen and two carbon atoms in the equatorial and two oxygen atoms in the axial positions. The solid state structure was established for 1a (R=Me) by X-ray analysis, and the agreement between the 119 Sn chemical shift in the solid state and in solution suggests that this structure is retained in solution. It was possible for the first time to determine isotope-induced chemical shifts 1 Δ 12/13 C( 119 Sn) for five-coordinate tin nuclei at natural abundance of 13 C. A positive sign of 1 Δ 12/13 C( 119 Sn) was found for R=Me ( 1a ), Bu ( 1b ) and Ph ( 1c ).

Ultrasmall particles and nanocomposites: state of the art

Synthesis, properties, and applications of ultrasmall particles (USPs, size/diameter <10 nm), so-called “ultrasmall nanoparticles”, are reviewed. USPs mainly consist of nanoparticles (with or without functionalization) of metallic gold, as well as iron and gadolinium oxides, all of which have important biomedical applications. Several other elemental metals and non-metals, oxides, salts, a few polymers and coordination compounds have also been obtained as USPs. Their main applications include biomedical uses {Magnetic Resonance Imaging (MRI) contract agents, virus inactivation, immunoassay labeling, etc.}, varieties of catalysis, hydrogen sorption, as magnetic devices, ultrasmall transistors, sensors for gases or biological objects, parts of solar cells and batteries, among others. Recent approaches, such as size-focusing methodology, for obtaining USPs and preventing their further agglomeration, are discussed.

New hexacyclic binuclear tin complexes derived from bis-(3,5-di-tert-butyl-2-phenol)oxamide

Abstract The syntheses of bis-(3,5-di-tert-butyl-2-phenol)oxamide (2a) and four new hexacyclic bimetallic tin compounds derivatives are reported: bis-(3,5-di-tert-butyl-2-oxo-phenyl)-oxamido-bis(dibutyltin) (3), bis-(3,5-di-tert-butyl-2-oxo-phenyl)-oxamido-bis-(diphenyltin) (4), bis(triethylammonium) bis-(3,5-di-tert-butyl-2-oxo-phenyl)-oxamido-bis-(dichlorobutyl-stannate) (5), and bis-[(OSn) ethanol]-bis-(3,5-di-tert-butyl-2-oxo-phenyl)-oxamido-bis-(chlorophenyltin) (6). All tin compounds show a planar ligand skeleton in which each tin atom is linked to the phenoxy group, to the anilinic nitrogen atom and to the oxygen of the oxamide group. Compounds 3 and 4 have two pentacoordinated diorganyl tin atoms with a distorted bpt geometry, whereas 5 contains a dianionic structure with two hexacoordinated tin atoms bonded to a n-butyl group and to two chlorine atoms and two triethyl ammonium as counterions. Compound 6 has two hexacoordinated tin atoms, each atom is bonded, in addition to the ligand, to one phenyl and one chlorine and coordinated to an ethanol molecule. Characterization of the compounds was made through usual analytical and spectroscopic methods. Structures of 4,6-di-tert-butyl-1-phenol-2-amine 1, the oxamide 2a and the four tin compounds 3–6 were established by the X-ray diffraction analyses.

Recent advances on ditopic ligands

Recent (2000–2009) achievements on ditopic ligands are reviewed. The ditopic ligands are mainly represented by N-, P-, O-, and S-containing organic molecules or their N, O-, N, S-, and N, P-combinations with azine, azole, amine, azide, β-diketone, crown ether, carboxylate, phenanthroline, oxazoline, phosphole, and thiophene moieties, among others. A series of mono- and polynuclear transition and f-metal complexes with these ligands, in particular cluster- and supramolecular unit-containing complexes, have been obtained and characterized spectroscopically and electrochemically.

New application of fluorescent organotin compounds derived from Schiff bases: synthesis, X-ray structures, photophysical properties, cytotoxicity and fluorescent bioimaging

A series of eight new organotin compounds derived from Schiff bases has been prepared by a multicomponent reaction from 2-hydroxy-1-naphthaldehyde or 4-substituted-2-hydroxybenzalhedyde, benzhydrazine, and the corresponding diorganotin oxide (R2SnO, R = nBu or Ph). All of the compounds were fully characterized by NMR (1H, 13C, and 119Sn), IR, UV/vis, elemental analyses and fluorescence spectroscopy. The crystal structures for some organotin compounds were determined by single crystal X-ray diffraction analysis. All of the compounds display fluorescence at room temperature with quantum yields of about 2 × 10-4 to 0.56. The cytotoxic activity and cellular imaging studies were carried out with the newly synthesized compounds. To the best of our knowledge, this is the first report of organotin compounds with Schiff base ligands investigated for fluorescence bioimaging (FBI).

Catalytic Acetylation Amines with Ethyl Acetate

The direct acetylation of various amines with ethyl acetate and {[Me2(MeC00)Sn]20}2 as catalyst is reported. Primary amines are acetylated in high yield while secondary bulky amines and aniline are obtained in low yield. A tentative mechanism is proposed. INTRODUCTION Acetylation of amines has numerous applications in synthetic organic chemistry, such as, a protective group or as a precursor of different functional groups. The reaction is usually achieved through acetylation with acetic anhydride /l/ , or under basic conditions /2,3,4/. Since basic or acid catalyst are often not suitable for sensitive functional groups, the development of new catalysts that allow the preparation of amides, under milder conditions, would increase the synthetic potential of this reaction. We are interested in a new direct synthetic procedure using organotin(IV) complexes as catalysts. Catalytic transesterification 151 and polymerizations 161 have been reported to be carried out under neutral conditions. In particular, transesterification studies with alcohols 151 (proton-donating nucleophiles) have been shown to react with different tin(IV) complexes to afford esters in good yields. We perceived that the use of tin(IV) complexes as catalyst could allow the acetylation reaction of amines in presence of ethyl acetate, in a similar fashion that an alcohol does in a transesterification reaction. This fact motivated us to investigate the potential of a direct synthesis of amides from the acetylation of several amines with ethyl acetate in the presence of dimethyltin(IV) acetic acid distannoxane (Scheme 1).

Recent Advances in Direct Synthesis of Organometallic and Coordination Compounds

Abstract In recent years (1980–2016), literature on “direct synthesis” of both coordination and organometallic compounds through interaction of metallic elements with organic substrates (ligands) present in a solid as well as liquid assistant grinding (LAG) phases have been reviewed. The synthesis of organometallic and coordination compounds, particularly heterometallic coordination compounds, remains a challenge for modern chemistry. Spontaneous self-assembly (SSA) is a primary approach that proceeds by broad screening, typically with simple, flexible ligands and available metal salts. The “direct synthesis” (DS) is a class of SSA, but prescribes the use of zero-valent metal(s) as a starting material, and typically forces deprotonation of the protic ligand(s) with the formation of unexpected products. The direct synthesis is successfully applied in preparation of heterometallic complexes. The aim of this review is to provide a broad but digestible overview of direct synthesis, i.e., reaction conducted by grinding solid reactants together with no, or a negligible amount, of solvent. We summarize our experience of complied data in the field of “direct synthesis” of heterorganometallic complexes with respect to the corresponding yields, covering preparative characterization and structural aspects.

One-pot microwave-assisted synthesis of organotin Schiff bases: an optical and electrochemical study towards their effects in organic solar cells

Four organotin compounds bearing Schiff bases were prepared via a multicomponent microwave-assisted reaction among 2-hydroxy-1-naphthaldehyde, 2-aminophenol derivatives and the corresponding diorganotin oxide (R2SnO, R = nBu or Ph), with high yields and a low economic/environmental impact. All of the compounds were fully characterized by NMR (1H, 13C, and 119Sn) spectroscopy, high-resolution mass spectrometry, X-ray diffraction, cyclic voltammetry, UV/Vis spectroscopy, and fluorescence spectroscopy. All of the compounds absorb in the visible region around 480–490 nm, close to the maximum solar emission, with an optical band gap of around 2.3 eV and low fluorescence quantum yields. According to the electrochemical study, they present LUMO values close to that of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM-C60), a typical electron acceptor organic photovoltaic material. Based on this combined optical/electrochemical study and as it allows the preparation of homogeneous spun films, the n-butyltin complex with carboxylic acid was selected for the investigation of its possible photovoltaic properties in organic solar cells. Charge photogeneration was obtained only using this organotin compound as an electron acceptor material with poly(3-hexylthiophene, P3HT) (typical electron donor material) with an open circuit voltage of 300 mV, a short-circuit current density of 0.11 mA cm−2 and an efficiency of 5.2 × 10−3%. Despite the fact that the efficiency is much lower with respect to the reference device P3HT/PCBM-C60, this preliminary result suggests that, after chemical and device processing optimization, tin complexes with Schiff bases could be applied as electron acceptor materials in organic photovoltaic devices.

Centrosymmetric Binuclear Boron Compounds Derived from Dithiooxamides: Synthesis, Characterization, and Their Photophysical Properties

In this paper, we report the synthesis and characterization of new boron compounds derived from dithiooxamides. The compounds were characterized by NMR (1H and 13C), UV-vis, fluorescence spectroscopy, and high resolution mass spectrometry. The crystal structure of the mononuclear boron compound was determined by single-crystal X-ray diffraction analysis. The photophysical properties of the boron compounds were investigated, and we found moderate fluorescence emission (compound 2 ΦF: 4.07% and compound 4 ΦF: 2.89%). We also observed that the mononuclear complex presented greater stability. Compound 4 showed interesting luminescent properties; in solid state, it exhibited an increase in fluorescence by mechanostimuli by changing to a bright red color, and also in solution, it showed a decrease in fluorescence intensity when oxygen and air were supplied to the solution.