Crystal structure of 4,4'-(disulfanedi-yl)dipyridinium chloride triiodide.

4,4'-(Disulfanedi-yl)dipyridinium chloride triiodide, C10H10N2S2 2+·Cl-·I3 -, (1) was synthesized by reaction of 4,4'-di-pyridyl-disulfide with ICl in a 1:1 molar ratio in di-chloro-methane solution. The structural characterization of 1 by SC-XRD analysis was supported by elemental analysis, FT-IR, and FT-Raman spectroscopic measurements.

Green Preparation of Antimicrobial 1D-Coordination Polymers: [Zn(4,4'-bipy)Cl2]∞ and [Zn(4,4'-bipy)2(OAc)2]∞ by Ultrasonication of Zn(II) Salts and 4,4'-Bipyridine.

We report on the green preparation of one-dimensional metal coordination polymers by sonochemical approach. The spacer ligand 4,4'-bipyridine was ultrasonicated with chloride or acetate zinc salts to obtain [Zn(4,4'-bipy)Cl2]∞ and [Zn(4,4'-bipy)2(OAc)2]∞, respectively. Benign solvents such as ethanol and water were selected as reaction media, and the synthesis took place in a few minutes-a very short time compared to conventional methods where some days' synthesis is required. X-ray powder diffraction, Fourier transform infrared spectroscopy, thermal analysis (thermogravimetric and differential scanning calorimetry), and CHN techniques investigated the influence of using different reaction solvents on the chemical, structural, and thermal properties of the final products. The 1D [Zn(4,4'-bipy)Cl2]∞ and [Zn(4,4'-bipy)2(OAc)2]∞ polymers, in agreement with the structures reported in the literature, were obtained in the form of nanocrystals with an average crystal size around 100 nm. As a proof of concept, a set of Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Klebsiella pneumoniae), and three yeast strains (Candida albicans, Candida krusei, Candida glabrata) were tested to evaluate the antimicrobial activity of the coordination polymers, following the Kirby-Bauer procedure and microplate dilution method. Thus, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and minimal biofilm inhibitory concentration (MBIC) were evaluated. Except for Candida krusei, the compounds showed an appreciable antimicrobial and antibiofilm activity against these strains grown in the liquid medium.

Grafting of the 2,8-dithia-5-aza-2,6-pyridinophane macrocycle on SBA-15 mesoporous silica for the removal of Cu2+ and Cd2+ ions from aqueous solutions: synthesis, adsorption, and complex stability studies.

Silica-based mesoporous materials have received growing attention in metal recovery from industrial processes, although, in general, the adsorption of metal ions by silanols is rather poor. Nevertheless, a great improvement of metal ion removal from aqueous solutions can be achieved by grafting metal-chelators on the particles' surface. Combining the metal-chelating properties of organic ligands with the high surface area of mesoporous silica particles makes these hybrid nanostructured materials a new horizon in metal recovery, sensing and controlled storage of metal ions in industrial and mining processes. Here, the 2,8-dithia-5-aza-2,6-pyridinophane (L) macrocycle was grafted on SBA-15 mesoporous silica to obtain the SBA-L mesoporous adsorbent for the removal and controlled recovery of Cd2+ and Cu2+ ions from aqueous solution in a broad pH range (4-11). By grafting about 0.3 mmol g-1 of L on SBA-15 a maximum loading capacity of 20.9 mg g-1 and 31.8 mg g-1 was obtained for Cu2+ and Cd2+, respectively. The adsorption kinetics can be described with the pseudo-second order model, while the adsorption isotherm (298 K) followed the Langmuir model. The latter, together with potentiometric studies, suggests that the adsorption mechanism is based on metal chelation by the grafted macrocycle. In summary, SBA-L is an effective copper(II) and cadmium(II) chelator for possible applications where metal removal, storage and recovery are of basic importance.

Glyphosate sensing in aqueous solutions by fluorescent zinc(II) complexes of [9]aneN3-based receptors.

Herein we describe the binding abilities of Zn(II) complexes of [12]aneN4- (L1) and [9]aneN3-based receptors (L2, L3) towards the herbicides N-(phosphonomethyl)glycine (glyphosate, H3PMG) and 2-amino-4-[hydroxy(methyl)phosphoryl]butanoic acid (glufosinate, H2GLU), and also aminomethylphosphonic acid (H2AMPA), the main metabolite of H3PMG, and phosphate. All ligands form stable Zn(II) complexes, whose coordination geometries allow a possible interaction of the metal center with exogenous anionic substrates. Potentiometric studies evidenced the marked coordination ability of the L2/Zn(II) system for the analytes considered, with a preferential binding affinity for H3PMG over the other substrates, in a wide range of pH values. 1H and 31P NMR experiments supported the effective coordination of such substrates by the Zn(II) complex of L2, while fluorescence titrations and a test strip experiment were performed to evaluate whether the H3PMG recognition processes could be detected by fluorescence signaling.

Can Serendipity Still Hold Any Surprises in the Coordination Chemistry of Mixed-Donor Macrocyclic Ligands? The Case Study of Pyridine-Containing 12-Membered Macrocycles and Platinum Group Metal Ions PdII, PtII, and RhIII.

This study investigates the coordination chemistry of the tetradentate pyridine-containing 12-membered macrocycles L1-L3 towards Platinum Group metal ions PdII, PtII, and RhIII. The reactions between the chloride salts of these metal ions and the three ligands in MeCN/H2O or MeOH/H2O (1:1 v/v) are shown, and the isolated solid compounds are characterized, where possible, by mass spectroscopy and 1H- and 13C-NMR spectroscopic measurements. Structural characterization of the 1:1 metal-to-ligand complexes [Pd(L1)Cl]2[Pd2Cl6], [Pt(L1)Cl](BF4), [Rh(L1)Cl2](PF6), and [Rh(L3)Cl2](BF4)·MeCN shows the coordinated macrocyclic ligands adopting a folded conformation, and occupying four coordination sites of a distorted square-based pyramidal and octahedral coordination environment for the PdII/PtII, and RhIII complexes, respectively. The remaining coordination site(s) are occupied by chlorido ligands. The reaction of L3 with PtCl2 in MeCN/H2O gave by serendipity the complex [Pt(L3)(m-1,3-MeCONH)PtCl(MeCN)](BF4)2·H2O, in which two metal centers are bridged by an amidate ligand at a Pt1-Pt2 distance of 2.5798(3) Å and feature one square-planar and one octahedral coordination environment. Density Functional Theory (DFT) calculations, which utilize the broken symmetry approach (DFT-BS), indicate a singlet d8-d8 PtII-PtII ground-state nature for this compound, rather than the alleged d9-d7 PtI-PtIII mixed-valence character reported for related dinuclear Pt-complexes.

Switching-On Fluorescence by Copper (II) and Basic Anions: A Case Study with a Pyrene-Functionalized Squaramide.

The new symmetric acyclic N,N'-bis(1-pyrenyl) squaramide (H2L) functionalized with the pyrene moiety as a fluorogenic fragment has been designed and its ability to selectively detect specific anions and metals investigated. H2L selectively binds Cl- both in solution (DMSO 0.5% H2O and MeCN) and in the solid state, and allows to selectively detect Cu2+ in MeCN with the formation of a 2:1 metal-receptor complex, with a green intense emission appreciable by naked eye under the UV lamp. The H2L copper complex preserves its emission properties in the presence of Cl-. The addition of basic anions (OH-, CN-, and F-) up to 10 equivalents caused the deprotonation of the squaramide NHs and a dramatic change of the emission properties of the H2L copper complex.

Simple squaramide receptors for highly efficient anion binding in aqueous media and transmembrane transport.

A family of acyclic squaramide receptors (L1-L5) have been synthesised with the aim to bind anions in a competitive solvent mixture and to evaluate how the presence of additional H-bond donor groups on the squaramide scaffold could affect the affinity towards anions and the transmembrane transport ability.

Aza- and Mixed Thia/Aza-Macrocyclic Receptors with Quinoline-Bearing Pendant Arms for Optical Discrimination of Zinc(II) or Cadmium(II) Ions.

The synthesis and coordination properties of two fluorescent chemosensors, featuring [9]aneN3 (1,4,7-triazacyclononane; L1) and [12]aneNS3 (1-aza-4,7,10-trithiacyclododecane; L2) as receptor units, and a quinoline pendant arm with an amide group as a functional group spacer are described. The optical responses of L1 and L2 in the presence of several metal ions were analysed in MeCN/H2 O (1 : 4 v/v) solutions. A selective chelation enhancement of fluorescence (CHEF) effect was observed in the presence of Zn2+ in the case of L1, and in the presence of Cd2+ in the case of L2, following the formation of a 1 : 1 and a 1 : 2 metal/ligand complex, respectively, which was also confirmed by potentiometric measurements. 1 H and 13 C NMR measurements in CD3 CN/CDCl3 in combination with molecular mechanics calculations show that for both complexes of L1 and L2 with Zn2+ and Cd2+ , respectively, the coordination of the carbonyl group from the pendant arm could be the origin of the observed optical selectivity.

Heavy metal tolerance of orchid populations growing on abandoned mine tailings: A case study in Sardinia Island (Italy).

Understanding how environmental pollutants influence plant occurrence, growth, and development is key for effective management plans and potential bioremediation. Rare plants, such as orchids, may occur in modified habitats and on soils containing heavy metals, yet their ecological and physiological responses to heavy metals is poorly understood. We investigated the influence of heavy metal pollution on orchid growth rates and interactions with soil fungal mutualists by comparing a large population of the orchid Epipactis helleborine (L.) Crantz subsp. tremolsii (Pau) E. Klein that grows on mine tailings in south-west Sardinia (Italy) with a population that grows on non-contaminated soils in central Sardinia. Soils of the contaminated site had high levels of heavy metals and low organic matter and nutritive elements content. We performed a morphological analysis on twenty individuals that have been subjected to measurement of bioaccumulation and translocation of heavy metals. Fungi associated with the roots of plants from the contaminated and uncontaminated site were grown and identified by DNA barcoding approach. Plants from the contaminated site were smaller than the ones growing in the uncontaminated site and were found to be able to tolerate heavy metals from the soil and to accumulate and translocate them into their organs. Fungi belonging to the genus Ilyonectria (Ascomycota) were found both in contaminated and uncontaminated sites, while an unidentified fungus was isolated from roots in the contaminated site only. These results are discussed in terms of orchids' tolerance to heavy metals and its physiological and ecological mechanisms. The role of contaminated habitats in harbouring orchids and peculiar taxa is also discussed.

[9]aneN3-based fluorescent receptors for metal ion sensing, featuring urea and amide functional groups.

We describe here the synthesis and coordination properties of three new derivatives of [9]aneN3 containing phenyl/quinoline pendant arm derivatives (L1, L2 and L3, respectively) also featuring urea (L1-L2) or amide (L3) functions as "non-innocent" spacers. At first, L1, L2 and L3 were studied considering the interaction with a series of anions (AcO-, BzO-, H2PO4-, F-, and Cl-) by means of 1H NMR measurements. Subsequently, the optical responses of L2 and L3 in the presence of several metal ions Cd2+, Co2+, Cu2+, Fe3+, Hg2+, K+, Mg2+, Mn2+, Ni2+, Zn2+ and Pb2 were analysed in MeCN/H2O (4 : 1 v/v). As observed by spectrophotometric and spectrofluorimetric titrations, there were significant changes in the absorbance and fluorescent emission of L2 upon addition of increasing amounts of Cd2+, Zn2+, Pb2+ and Cu2+ in MeCN/H2O (4 : 1 v/v). In particular, titrations of L2 with Cd2+, Zn2+ or Pb2+ showed an almost comparable CHEF effect up to an M2+/L2 molar ratio of 1. Overall, no significant optical selectivity was observed in the case of L2. Conversely, L3 revealed an OFF-ON selective response only in the presence of the Zn2+ ion in MeCN/H2O (4 : 1 v/v), which can be attributed to the formation of both 1 : 1 and 1 : 2 metal-to-ligand complexes, as also confirmed by potentiometric measurements. Finally, crystals of [ZnL1(Ac)](Ac) (1), [CuL1(Cl)](Cl)·H2O (2) and [CuL3](NO3) (3) were grown and analysed by X-ray diffraction. 1 and 3 feature the metal center in a pseudo-octahedral coordination geometry coordinated also by the carbonyl group from one pendant arm, while in the case of 2, one of the six coordination sites in the final distorted octahedral geometry is occupied by the nitrogen donor from the urea group of one pendant arm.

A Fluorescent Sensor Array Based on Heteroatomic Macrocyclic Fluorophores for the Detection of Polluting Species in Natural Water Samples.

The development of a novel all-solid-state optical sensor array based on heteroatomic macrocyclic fluorophores (diaza-crown ether, metallocorrole and pyridinophans) for the photographic analysis of liquid media, is presented. The sensitivity of the new optical system toward a number of different species (cations: Li+, K+, Na+, NH4+ , Mg2+, Ca2+, Co2+, Cu2+, Zn2+, Cd2+, Pb2+ and anions: NO2- , NO3- , Cl-, Br-, HCO3- ) was evaluated both in single selective sensor mode and in multisensory arrangement. The satisfactory PLS1 regression models between sensor array optical response and analyte concentration were obtained for Cd2+, Cu2+, Zn2+, and NO2- ions in all the range of tested concentrations. Among these species the highest attention was focused onto detection of cadmium and nitrite ions, for which the detection limits, DL, estimated by 3σ method were found 0.0013 mg/L and 0.21 mg/L respectively, and these values are lower than the corresponding WHO guideline values of 0.003 mg/L (Cd2+) and 2 mg/L ( NO2- ). The suitability of the developed sensors implemented with familiar devices for signal acquisition (Light Emitting Diode, LED, as light source and a digital camera as a signal detector), and chemometric methods for data treatment to perform fast and low-cost monitoring of species under interest, in real samples of environmental importance, is demonstrated.

Dyspnoea, thoracic pain and fever in a young caucasian female: A case report.

INTRODUCTION: The diagnostic approach to patients with mediastinal pathology is not always simple and an improper diagnostic work-up can lead to significant diagnosis delay. PRESENTATION OF CASE: We report on the case of a young woman who was admitted to the Emergency Department complaining of thoracic pain, dyspnoea, fever and productive cough. The physical examination showed a painful swelling over the sternum's upper left margin, which had become evident 4 months earlier. A Computer Tomography showed the presence of a retrosternal oval lesion (5.5 x 4 cm) infiltrating the thoracic wall and showed the presence of discretely enlarged mediastinal lymph nodes in several mediastinal stations. DISCUSSION: The Multidisciplinary Team decided to perform an ultrasound-guided biopsy of the retrosternal mass that showed an inflammatory pattern, whereas microbiology tests proved negative. The lack of improvement with medical therapy (non steroideal anti-inflammatories and antibiotics) and the clinical suspicion of malignancy led us to perform a surgical biopsy of the mass that finally proved to be diagnostic for Hodgkin's lymphoma. CONCLUSIONS: Mediastinal masses with an aggressive behavior, should always be considered to be potentially malignant. Surgical biopsy, sometimes, can be the only way to correctly diagnose the pathological process, especially in the case of Hodgkin's lymphoma in which few diagnostic cells (Reed-Sternberg cells) are generally embedded in an abundant inflammatory background tissue.

A new class of silica-supported chromo-fluorogenic chemosensors for anion recognition based on a selenourea scaffold.

The first example of a chemosensor (L) containing a selenourea moiety is described here. L is able to colorimetrically sense the presence of CN- and S2- in H2O : MeCN (75 : 25, v/v). Moreover, when L is loaded into functionalised mesoporous silica nanoparticles an increase in the selectivity towards S2- occurs via a selective fluorescence response.

Di- and Triphosphate Recognition and Sensing with Mono- and Dinuclear Fluorescent Zinc(II) Complexes: Clues for the Design of Selective Chemosensors for Anions in Aqueous Media.

The synthesis of a new ligand (L1) containing two 1,4,7-triazacyclononane ([9]aneN3 ) moieties linked by a 4,5-dimethylenacridine unit is reported. The binding and fluorescence sensing properties toward Cu2+ , Zn2+ , Cd2+ , and Pb2+ of L1 and receptor L2, composed of two [9]aneN3 macrocycles bridged by a 6,6''-dimethylen-2,2':6',2''-terpyridine unit, have been studied by coupling potentiometric, UV/Vis absorption, and emission measurements in aqueous media. Both receptors can selectively detect Zn2+ thanks to fluorescence emission enhancement upon metal binding. The analysis of the binding and sensing properties of the Zn2+ complexes toward inorganic anions revealed that the dinuclear Zn2+ complex of L1 selectively binds and senses the triphosphate anion (TP), whereas the mononuclear Zn2+ complex of L2 displays selective recognition of diphosphate (DP). Binding of TP or DP induces emission quenching of the Zn2+ complexes with L1 and L2, respectively. These results are exploited to discuss the role played by pH, number of coordinated metal cations, and binding ability of the bridging units in metal and/or anion coordination and sensing.

Re(I) derivatives functionalised with thioether crowns containing the 1,10-phenanthroline subunit as a new class of chemosensors.

A series of luminescent fac-[Re(CO)3(L)(NN)](+) complexes, where L is a pyridine or an imidazole and NN is the 1,10-phenanthroline subunit of mixed donor pentadentate thioether crowns have been synthesised and their luminescence properties have been analysed. Then, heterometallic Re(i)/Au(i) complexes, with the Au(i) fragment bonded directly to the imidazole ligand, and heterometallic Re(i)/Ag(i) complexes, with the silver fragment coordinating the S-donor thioether linker of the rings have also been prepared. Analysis of their luminescence properties showed a considerable blue shift of the emission maxima for the Re(i)/Ag(i) derivatives, upon coordination of the silver centre to the S-donor atoms of the aliphatic chain of the macrocyclic units.

Silica-based nanoparticles: a versatile tool for the development of efficient imaging agents.

This review describes the recent advances in the development of imaging agents based on silica nanoparticles. Different techniques (magnetic resonance imaging, optical imaging, positron emission tomography, X-ray computed tomography, and ultrasound imaging) are described as well as the possibility of combining together different imaging techniques in the same nanoplatform and simultaneously performing imaging and therapy.

Silver ion imprinted polymer nanobeads based on a aza-thioether crown containing a 1,10-phenanthroline subunit for solid phase extraction and for voltammetric and potentiometric silver sensors.

A new nano-sized silver(I) ion-imprinted polymer (IIP) was prepared via precipitation copolymerization using ethyleneglycol dimethacrylate, as a cross-linking agent in the presence of Ag(+) and an aza-thioether crown containing a 1,10-phenanthroline subunit as a highly selective complexing agent. The imprint silver(I) ion was removed from the polymeric matrix using a 1.0M HNO3 solution. The resulting powder material was characterized using IR spectroscopy and scanning electron microscopy. The SEM micrographs showed colloidal nanoparticles of about 52 nm and 75 nm in diameter and slightly irregular in shape for leached and unleached IIPs, respectively. The optimal pH for quantitative enrichment was 6.0 and maximum sorbent capacity of the prepared IIP for Ag(+) was 18.08 µmol g(-1). The relative standard deviation and limit of detection (LOD=3Sb/m) for flame atomic absorption spectrometric determination of silver(I) ion, after its selective extraction by the prepared IIP nanobeads, were evaluated as 2.42% and 2.2×10(-8) M, respectively. The new Ag(+)-IIP was also applied as a suitable sensing element to the preparation of highly selective and sensitive voltammetric and potentiometric sensors for ultra trace detection of silver(I) ion in water samples, with limits of detection of 9.0×10(-10) and 1.2×10(-9) M, respectively.

An OFF-ON chemosensor for biological and environmental applications: sensing Cd2+ in water using catanionic vesicles and in living cells.

A new OFF-ON fluorescent chemosensor (L(1)) for Cd(2+) recognition based on a 5-chloro-8-hydroxyquinoline pendant arm derivative of 1,4,7-triazacyclononane ([9]aneN3) will be presented and its photochemical features in an MeCN-H2O 1 : 1 (v/v) mixture, in pure water, after inclusion within catanionic vesicles, and in living cells will be discussed. The coordination properties of L(1) both in solution and in the solid state were preliminarily studied and its selectivity towards Cd(2+)versus a set of different metal ions (Cu(2+), Zn(2+), Cd(2+), Pb(2+), Al(3+), Hg(2+), Co(2+), Ni(2+), Mn(2+), Mg(2+), K(+), Ca(2+), Ag(+), and Na(+)) was verified in MeCN-H2O 1 : 1 (v/v). In water, upon addition of increasing amounts of Cd(2+) to L(1) an enhancement of the fluorescence emission was detected. To overcome this serious drawback, L(1) was dissolved in an innovative catanionic vesicular solution based on sodium bis(2-ethylhexyl) sulfosuccinate, a traditional surfactant, and 1-dodecyl-3-methylimidazolium bromide, an ionic liquid. When enclosed within the vesicle bilayers in water, L(1) restored its fluorescence emission property upon addition of Cd(2+). Remarkably, L(1) enters the cellular membrane of living cells thus allowing the detection of intracellular Cd(2+). These findings encourage the application of this new fluorescent chemosensor in real samples for histological and environmental analyses.

Multimodal use of new coumarin-based fluorescent chemosensors: towards highly selective optical sensors for Hg(2+) probing.

Despite several types of fluorescent sensing molecules have been proposed and examined to signal Hg(2+) ion binding, the development of fluorescence-based devices for in-field Hg(2+) detection and screening in environmental and industrial samples is still a challenging task. Herein, we report the synthesis and characterization of three new coumarin-based fluorescent chemosensors featuring mixed thia/aza macrocyclic framework as receptors units, that is, ligands L1-L3. These probes revealed an OFF-ON selective response to the presence of Hg(2+) ions in MeCN/H2 O 4:1 (v/v), which allowed imaging of this metal ion in Cos-7 cells in vitro. Once included in silica core-polyethylene glycol (PEG) shell nanoparticles or supported on polyvinyl chloride (PVC)-based polymeric membranes, ligands L1-L3 can also selectively sense Hg(2+) ions in pure water. In particular we have developed an optical sensing array tacking advantage of the fluorescent properties of ligand L3 and based on the computer screen photo assisted technique (CSPT). In the device ligand L3 is dispersed into PVC membranes and it quantitatively responds to Hg(2+) ions in natural water samples.

Zn2+/Cd2+ optical discrimination by fluorescent chemosensors based on 8-hydroxyquinoline derivatives and sulfur-containing macrocyclic units.

Four new fluorescent chemosensors for metal ions based on 8-hydroxyquinoline (8-HDQ) derivatives and sulfur-containing macrocyclic units were synthesized and characterized, namely 1-(5-chloro-8-hydroxy-7-quinolinylmethyl)-1-aza-4,7,10-trithiacyclododecane (L1), 1-(5-chloro-8-hydroxy-7-quinolinylmethyl)-1-aza-4,13-dithia-7,10-dioxacyclopentadecane (L2), 1-(8-hydroxy-2-quinolinylmethyl)-1-aza-4,7,10-trithiacyclododecane (L3), and 1-(8-hydroxy-2-quinolinylmethyl)-1-aza-4,13-dithia-7,10-dioxacyclopentadecane (L4). Preliminary fluorimetric titrations indicated L1 as the only member of the family of ligands to give a selective CHEF-type response to the presence of Zn(2+) in MeCN-H2O (1:1, v/v) solutions, which allowed imaging of this metal ion in Cos-7 cells in vitro. The other ligands either did not show any fluorescence response (L3, L4) to any of the metal ions considered (Cu(2+), Zn(2+), Cd(2+), Hg(2+) and Pb(2+)) or gave (L2) a CHEF-type response also to the presence of Cd(2+). The coordination properties of L1 towards Zn(2+) were, therefore, fully investigated by potentiometric measurements and absorption and emission spectroscopy at different pH values, which indicated that the formation of 2:1 L1/Zn(2+) complexes is responsible for the CHEF-type effect observed. The complexes [Zn(L1)2H2O](BF4)2 and [Zn(L3)](ClO4)2 were characterized in the solid state by X-ray crystallography, and DFT calculations were performed to understand the origin of the Zn(2+)/Cd(2+) optical discrimination of the 8-HDQ-based "conjugate" fluorescent chemosensors reported.