Interesting chemical and physical features of the products of the reactions between trivalent lanthanoids and a tetradentate Schiff base derived from cyclohexane-1,2-diamine.

The initial use of a tetradentate Schiff base (LH) derived from the 2 : 1 condensation between 2-hydroxyacetophenone and cyclohexane-1,2-diamine in 4f-metal chemistry is described. The 1 : 2 reaction of Ln(NO)·HO (Ln = lanthanoid or yttrium) and LH in MeOH/CHCl has provided access to isostructural complexes [Ln(NO)(L'H)(MeOH)] in moderate to good yields. Surprisingly, the products contain the corresponding Schiff base ligand L'H possessing six aliphatic -CH- groups instead of the -CH-(CH)-CH- unit of the cyclohexane ring, an unusual ring-opening of the latter has occurred.

pH-Sensitive Gold Nanorods for Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) Delivery and DNA-Binding Studies.

A facile experimental protocol for the synthesis of poly(ethylene glycol)-modified (PEGylated) gold nanorods (AuNRs@PEG) is presented as well as an effective drug loading procedure using the non-steroidal anti-inflammatory drug (NSAID) naproxen (NAP). The interaction of AuNRs@PEG and drug-loaded AuNRs (AuNRs@PEG@NAP) with calf-thymus DNA was studied at a diverse temperature revealing different interaction modes; AuNRs@PEG may interact via groove-binding and AuNRs@PEG@NAP may intercalate to DNA-bases. The cleavage activity of the gold nanoparticles for supercoiled circular pBR322 plasmid DNA was studied by gel electrophoresis while their affinity for human and bovine serum albumins was also evaluated.

Development of Antifouling Coatings Based on Quaternary Ammonium Compounds through a Multilayer Approach.

The development of polymeric materials as antifouling coatings for aquaculture nets is elaborated in the present work. In this context, cross-linked polymeric systems based on quaternary ammonium compounds (immobilized or releasable) prepared under mild aqueous conditions were introduced as a more environmentally friendly methodology for coating nets on a large scale. To optimize the duration of action of the coatings, a multilayer coating method was applied by combining the antimicrobial organo-soluble copolymer poly(cetyltrimethylammonium 4-styrenesulfonate-co-glycidyl methacrylate) [P(SSAmC-co-GMA20)] as the first layer with either the water-soluble copolymer poly(vinylbenzyl trimethylammonium chloride-co-acrylic acid) [P(VBCTMAM-co-AA20)] or the water-soluble polymers poly(acrylic acid) (PAA) and poly(hexamethylene guanidine), PHMG, as the second layer.

Biological Effects of Human Exposure to Environmental Cadmium.

Cadmium (Cd) is a toxic metal for the human organism and for all ecosystems. Cd is naturally found at low levels; however, higher amounts of Cd in the environment result from human activities as it spreads into the air and water in the form of micropollutants as a consequence of industrial processes, pollution, waste incineration, and electronic waste recycling. The human body has a limited ability to respond to Cd exposure since the metal does not undergo metabolic degradation into less toxic species and is only poorly excreted.

Stimuli-responsive spin crossover nanoparticles for drug delivery and DNA-binding studies.

Aminated silica hybrid, spin-crossover (SCO) nanoparticles (AmNPs) coupled with ()-naproxen (NAP) were proposed for potential drug nanocarriers through drug release experiments at various pH values. DNA- and albumin-binding studies were also carried out using diverse techniques in order to investigate the interaction of the nanoparticles with calf-thymus DNA and serum albumins and to determine the corresponding binding constants.

Two different coordination modes of the Schiff base derived from ortho-vanillin and 2-(2-aminomethyl)pyridine in a mononuclear uranyl complex.

This work describes the reaction of the potentially tetradentate Schiff-base ligand -(2-pyridylmethy)-3-methoxysalicylaldimine (HL) with UO(OCMe)·2HO and UO(NO)· 6HO in MeOH in the absence or presence of an external base, respectively. The product from these reactions is the mononuclear complex [UO(L)] (). Its structure has been determined by single-crystal, X-ray crystallography.

Structural Identification of Metalloproteomes in Marine Diatoms, an Efficient Algae Model in Toxic Metals Bioremediation.

The biosorption of pollutants using microbial organisms has received growing interest in the last decades. Diatoms, the most dominant group of phytoplankton in oceans, are (i) pollution tolerant species, (ii) excellent biological indicators of water quality, and (iii) efficient models in assimilation and detoxification of toxic metal ions. Published research articles connecting proteomics with the capacity of diatoms for toxic metal removal are very limited.

Application of a catalytic oxidation method for the simultaneous determination of total organic carbon and total nitrogen in marine sediments and soils.

This study presents the application of a simultaneous method for the determination of total organic carbon (TOC) and total nitrogen (TN) in marine sediments and soils, using a data set of 206 samples collected from coastal lagoonal/marine sedimentary environments and certified reference materials (CRMs). TOC and TN were determined using the high temperature (720°C) catalytic (Pt/Al2O3) oxidation method and the detection of TOC and TN was performed using an infrared or a chemiluminescence detector, respectively. Results from the abovementioned TOC method were compared with the results from the widely used Wakley-Black titration method, while TN results with these from elemental analysis.

Dinuclear Lanthanide(III) Complexes from the Use of Methyl 2-Pyridyl Ketoxime: Synthetic, Structural, and Physical Studies.

The first use of methyl 2-pyridyl ketoxime (mepaoH) in homometallic lanthanide(III) [Ln(III)] chemistry is described. The 1:2 reactions of Ln(NO)·HO (Ln = Nd, Eu, Gd, Tb, Dy; = 5, 6) and mepaoH in MeCN have provided access to complexes [Ln(OCMe)(NO)(mepaoH)] (Ln = Nd, ; Ln = Eu, ; Ln = Gd, ; Ln = Tb, ; Ln = Dy, ); the acetato ligands derive from the Ln-mediated hydrolysis of MeCN. The 1:1 and 1:2 reactions between Dy(OCMe)·4HO and mepaoH in MeOH/MeCN led to the all-acetato complex [Dy(OCMe)(mepaoH)] ().

Indium(III) in the "Periodic Table" of Di(2-pyridyl) Ketone: An Unprecedented Transformation of the Ligand and Solid-State In NMR Spectroscopy as a Valuable Structural Tool.

Reactions of di(2-pyridyl) ketone, (py)CO, with indium(III) halides in CHNO have been studied, and a new transformation of the ligand has been revealed. In the presence of In, the C═O bond of (py)CO is subjected to nucleophilic attack by the carbanion :CHNO, yielding the dinuclear complexes [InX{(py)C(CHNO)(O)}] (X = Cl, ; X = Br, ; X = I, ) in moderate to good yields. The alkoxo oxygens of the two η:η:η-(py)C(CHNO)(O) ligands doubly bridge the In centers and create a {In(μ-OR)} core.

Polymeric Coatings Based on Water-Soluble Trimethylammonium Copolymers for Antifouling Applications.

Crosslinked polymeric materials based on a quaternary trimethylammonium compound were developed and evaluated as potential antifouling coatings. For this purpose, two water-soluble random copolymers, poly(4-vinylbenzyltrimethylammonium chloride-co-acrylic acid) P(VBCTMAM-co-AAx) and poly(N,N-dimethylacrylamide-co-glycidylmethacrylate) P(DMAm-co-GMAx), were synthesized via free radical polymerization. A water based approach for the synthesis of P(VBCTMAM-co-AAx) copolymer was used.

Tetranuclear oxido-bridged thorium(iv) clusters obtained using tridentate Schiff bases.

Thorium(iv) complexes are currently attracting intense attention from inorganic chemists due to the development of liquid-fluoride thorium reactors and the fact that thorium(iv) is often used as a model system for the study of the more radioactive Np(iv) and Pu(iv). Schiff-base complexes of tetravalent actinides are useful for the development of new separation strategies in nuclear fuel processing and nuclear waste management. Thorium(iv)-Schiff base complexes find applications in the colorimetric detection of this toxic metal ion and the construction of fluorescent on/off sensors for Th(iv) exploiting the ligand-based light emission of its complexes.

Multifunctionality in Two Families of Dinuclear Lanthanide(III) Complexes with a Tridentate Schiff-Base Ligand.

The employment of -(2-carboxyphenyl)salicylideneimine in 4f metal chemistry has led to two families of dinuclear complexes depending on the lanthanide(III) used. Representative members exhibit interesting magnetic, optical, and catalytic properties.

Structural diversity in Ni(II) cluster chemistry: Ni5, Ni6, and {NiNa2}n complexes bearing the Schiff-base ligand N-naphthalidene-2-amino-5-chlorobenzoic acid.

The employment of the fluorescent bridging and chelating ligand N-naphthalidene-2-amino-5-chlorobenzoic acid (nacbH2) in Ni(II) cluster chemistry has led to a series of pentanuclear and hexanuclear compounds with different structural motifs, magnetic and optical properties, as well as an interesting 1-D coordination polymer. Synthetic parameters such as the inorganic anion present in the NiX2 starting materials (X = ClO4(-) or Cl(-)), the reaction solvent and the nature of the organic base employed for the deprotonation of nacbH2 were proved to be structure-directing components. Undoubtedly, the reported results demonstrate the rich coordination chemistry of nacbH2 in the presence of Ni(II) metal ions and the ability of this chelate to adopt a variety of different modes, thus fostering the formation of high-nuclearity molecules with many physical properties.

Dinuclear lanthanide(III)/zinc(II) complexes with methyl 2-pyridyl ketone oxime.

The first use of methyl 2-pyridyl ketone oxime (mpkoH) in zinc(II)/lanthanide(III) chemistry leads to the [ZnLn(mpko)3(mpkoH)3](ClO4)2 and [ZnLn(NO3)2(mpko)3(mpkoH)] families of dinuclear Zn(II)Ln(III) complexes displaying blue-green, ligand-based photoluminescence; the Zn(II)Dy(III) compound shows field-induced relaxation of magnetization.

Fluorescent naphthalene diols as bridging ligands in Ln(III) cluster chemistry: synthetic, structural, magnetic, and photophysical characterization of Ln(III)8 "Christmas stars".

The initial employment of the fluorescent bridging ligand naphthalene-2,3-diol in 4f-metal coordination chemistry has provided access to a new family of Ln(III)8 clusters with a "Christmas-star" topology, single-molecule magnetism behavior, and ligand-centered emissions.

Tetranuclear lanthanide(III) complexes with a zigzag topology from the use of pyridine-2,6-dimethanol: synthetic, structural, spectroscopic, magnetic and photoluminescence studies.

Reaction between Ln(NO3)3·xH2O (x = 5 or 6) and the potentially tridentate (N,O,O) chelating/bridging ligand pyridine-2,6-dimethanol (pdmH2), in the presence of base NEt3, affords a family of isostructural tetranuclear [Ln(III)4(NO3)2(pdmH)6(pdmH2)2](NO3)4 (Ln(III) = Eu(III), Gd(III), Tb(III), Dy(III), Ho(III), Er(III), Yb(III)) complexes with a rare zigzag topology. All complexes contain a [Ln4(μ-OR)6](6+) core with bridging ligation provided by the alkoxido arms of six η(1):η(1):η(2):μ pdmH(-) groups. The Ln(III) ions are eight coordinate with distorted geometries.

Emissive molecular nanomagnets: introducing optical properties in triangular oximato {Mn(III)3} SMMs from the deliberate replacement of simple carboxylate ligands with their fluorescent analogues.

The targeted replacement of acetate groups in the optically inactive [Mn(III)3O(O2CMe)3(mpko)3](ClO4) single-molecule magnet with their naphthalene, anthracene, and pyrene fluorescent analogues has led to three new emissive SMMs with enhanced photoluminescence properties and potential applications in the field of molecular electronics.

Dinuclear lanthanide(III) complexes by metal-ion-assisted hydration of di-2-pyridyl ketone azine.

The initial employment of di-2-pyridyl ketone azine in 4f metal chemistry has led to a unique ligand transformation; the resulting anionic ligand is able to bridge two Ln(III) ions, affording neutral and cationic dinuclear complexes with interesting properties.

Investigation of the zinc(II)-benzoate-2-pyridinealdoxime reaction system.

The employment of pyridine-2-carbaldehyde oxime (paoH) in zinc(II) benzoate chemistry, in the absence or presence of azide ions, is described. The syntheses, crystal structures and spectroscopic characterization are reported for the complexes [Zn(O(2)CPh)(2)(paoH)(2)] (1), [Zn(12)(OH)(4)(O(2)CPh)(16)(pao)(4)] (2) and [Zn(4)(OH)(2)(pao)(4)(N(3))(2)] (3). The Zn(II) centre in octahedral 1 is coordinated by two monodentate PhCO(2)(-) groups and two N,N'-chelating paoH ligands.

A new family of nonanuclear lanthanide clusters displaying magnetic and optical properties.

The initial employment of 2-(hydroxymethyl)pyridine in 4f metal chemistry has afforded a new family of Ln(III)(9) clusters with a sandglass-like topology and dual physical properties; the Dy(III) member shows single-molecule magnetism behavior, while the Eu(III) analogue exhibits intense red photoluminescence.

A tetrahedron in a cube: a dodecanuclear Zn(II) benzoate cluster from the use of 2-pyridinealdoxime.

The reactions of 2-pyridinealdoxime with Zn(O(2)CPh)(2)·2H(2)O have led to a mononuclear complex and a dodecanuclear cluster; the Zn(12) compound, whose metallic skeleton describes a tetrahedron encapsulated in a distorted cube, is the biggest Zn(II) oxime cluster discovered to date and displays photoluminescence with a maximum at 354 nm upon maximum excitation at 314 nm.

Adsorption of dyes on Sahara desert sand.

Sahara desert sand (SaDeS) was employed as a mineral sorbent for retaining organic dyes from aqueous solutions. Natural sand has demonstrated a strong affinity for organic dyes but significantly lost its adsorption capacity when it was washed with water. Therefore, characterization of both natural and water washed sand was performed by XRD, BET, SEM and FTIR techniques.

Study of the conditions affecting dye adsorption on titania films and of their effect on dye photodegradation rates.

Nanocrystalline titania films have been deposited on glass slides by the sol-gel technique in the presence of surfactant, which plays the role of template of the nanostructure. Several different dyes, both anionic and cationic, have been adsorbed on these films from aqueous solutions. Some of these dyes were adsorbed at large quantities some at lower quantities.