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Metal acetate complexes are highly interesting in designing and synthesizing metal–organic frameworks, which have potential applications in gas storage, molecular sieves, ion exchange, and catalysis. Cadmium is well recognized as an industrial pollutant and a food contaminant that severely affects human health. For these reasons, the detection and analysis of Cd are of great interest. A major challenge in studying cadmium compounds' structure is that Cd2+ can have a wide range of coordination numbers and diverse geometries. (MA)LDI is extremely useful for detecting Cd(OAc)2·2H2O and investigating Cd's complex and flexible nature. We applied LDI to detect and characterize the Cd-related clusters and MALDI approach to investigate the Cd(OAc)2x2H2O reactivity and detectability with the five different organic matrices. The results revealed that in the solid-state Cd(OAc)2x2H2O tend to form coordination polymers, and in the presence of coordinating ligands (matrix molecules) form smaller complexes. In addition, the correlation between Cd-related LOD and matrix features was observed and discussed, indicating that the LODs of this analyte strongly depend on the optical absorption of the matrix-analyte adduct.

An electronic nose system (E-nose) with metal oxide semiconductor sensors (MOS) has been designed to discriminate and quantify different chemical warfare agents (CWA) mimics. The E-nose consists of an array of commercial MOS for different gases, two sensors for temperature sensing, a sample handling system, a data acquisition system and a laptop with the data acquisition system control. With this device, discrimination studies have been carried out to detect specific CWA simulants (diethyl chlorophosphonate (DCP), diethyl cyanophosphate (DCNP), diisipropyl fluoride (DFP)), their derivatives (diethyl 1-phenylethyl phosphonate (OP-1), diethyl (2- cyanoethyl)phosphonate (OP-2), dimethyl methyl phosphonate (OP-3) and diethyl (2-oxopropyl)phosphonate (OP-4)) and some potential interfering substances (sulfuric acid, ammonia, ethanol and acetone). Principal components analyses (PCA) show that it is possible to discriminate the studied organophosphorous CWA mimics (DCP, DCNP and DFP) from the other studied derivatives and potential interfering agents. In addition, DCNP quantification studies have been done by using partial least squares (PLS) and a mathematical model has been obtained to predict DCNP concentrations in air. In this model, the coefficient of determination (R2) is 0.9567, the root mean square error of prediction (RMSEP) is 30 and the limit of detection (LOD) is 5 ppm so the model is considered valid. These results suggest that this E-nose system is capable to discriminate and quantify CWA mimics and it would be a feasible system to be used in a real scenario., Financial support from the Spanish Government (MAT2009-14564-C04-02 and MAT2009-14564-C04-01), the Grant BES-2010-034031 from the FPI-MINECO Subprogram and the Spanish Government and European FEDER funds (MAT2012-38429-C04-04) are gratefully acknowledged.

A humid electronic nose device based on pulse voltammetry has been applied to detect nerve agentsimulants in gas phase. The humid electronic nose consists in a polypropylene piece which containsan array of eight metallic electrodes (i.e., Ir, Rh, Pt, Au Ag, Co, Cu and Ni) divided into two sets of fourworking electrodes housed inside a homemade steel cylinder, and a salt bridge connection to a referenceelectrode. The electrochemical system is fitted to a nylon membrane damped with a background solutionof sodium tetraborate 0.01 M by a second polypropylene piece. The PCA analysis demonstrated that thesystem is able to discern principal organophosphorous nerve agent mimics (DCP, DCNP and DFP) fromorganophosphorous derivatives and some other potential interferents. Besides, the PLS quantificationanalysis showed sound accuracy in the concentration prediction for DCNP in air, good linearity and alimit of detection (LOD) of some a few ppm., Financial support from the Spanish Government (project MAT2012-38429-004) and the Generalitat Valenciana (project PROMETEO/2009/016) is gratefully acknowledged. L.P. is grateful to the Universitat Politecnica de Valencia for her grant.

In order to monitor the chloride penetration processes, a potentiometric embedded thick-film sensor was developed. This paper includes the results of research on the characterization of Cl− sensors made of Ag/AgCl resistive pastes (materials, sensitivity and detection limit, reproducibility, reversibility and response time, long-term performance and reliability in the presence of interfering agents). Theoretical expressions have been developed to describe the potentiometric response including the presence of OH− and bromide ions. The study shows that thick-film sensors are able to monitor Cl− activity as a function of the redox potential. Sensors are also capable of providing reliable and continuous real-time information on phenomena related to the progress of the chloride penetration front in concrete specimens. These sensors are a promising tool because thick-film technology allows us to obtain miniaturized, low-cost, robust and stable long-term sensors for Cl− monitoring., The pre-doctoral scholarship granted to Roman Bataller Prats within the program "Formacion de Personal Investigador (FPI) 2012" from Universitat Politecnica de Valencia is gratefully acknowledged.

This paper proposes a reasonable methodology for the design of pulse arrays applied in classification and quantification techniques based on the use of pulse voltammetric electronic tongues. As model problem we designed a procedure to predict levels of ferrocene, TCNQ and Ru(bipy)(3)(2+) using a voltammetric electronic tongue employing a set of noble electrodes; i.e. Au, Pt, Ir and Rh. Ferrocene, TCNQ and Ru(bipy)(3)(2+) have been selected as model compounds because these are molecules with well-defined redox processes. The electrodes were housed inside a stainless steel cylinder which was used as the body of the electronic tongue system. A SCE was used as reference electrode. An electrochemical study of the response of ferrocene TCNQ and Ru(bipy)(3)(2+) was carried out as a first step with the aim of characterise the redox processes in these compounds. Different samples containing ferrocene,TCNQ and Ru(bipy)(3)(2+) were prepared following an experimental design in which a system of three compounds/three levels was established. Multivariate analysis based on Partial Least Square (PLS) techniques was applied for data management and prediction models building. Several set of pulses were tested and a general procedure to their design for their use in voltammetric electronic tongues is discussed and proposed. (C) 2011 Elsevier B.V. All rights reserved., We thank the Spanish Government (projects MAT2009-14564-C04-01), Generalitat Valenciana (project PROMETEO/2009/016) for support. PCI-Mediterraneo A/024590/09/A/03044/10) and the UPV (project PAID-05-10) are gratefully acknowledged.

A method for predicting levels of chloride, nitrite and nitrate in minced meat by using an electronic tongue based on pulse voltammetry is proposed here. The electronic tongue consists of a set of noble (Au, Pt, Rh, Ir, Ag) and non-noble (Ni, Co, Cu) electrodes that were housed inside a stainless steel cylinder used at the same time as both the body of the electronic tongue system and the counter/reference electrode. An electrochemical study of the response of the anions Cl − , NO 3 − and NO 2 − using the different noble and non-noble electrodes was carried out in water in order to design a set of pulses for the electronic tongue. The determination of the concentration of chloride, nitrate and nitrite with the voltammetric tongue was carried out on both saline solutions (brines) and minced meat. The addition of the salts was performed following an experimental design in which a system of three compounds/three levels was established. Multivariate analysis including cross validation and partial least square (PLS) techniques were applied for data management and prediction models building. A very good prediction of the concentration of the anions chloride, nitrate and nitrite was achieved in brines. In minced meat, PLS models showed reduction in the prediction capabilities caused by a matrix effect, nevertheless the system still shows good accuracy and precision in the determination of concentration levels of these anions.

A novel two-step protocol for the colorimetric detection of ionic surfactants was developed using simple silica supports functionalised with suitable binding groups. Solid S1 was synthesised by reaction of silica with N-methyl-N′-propyltrimethoxysilylimidazolium chloride to obtain a final solid containing imidazolium coordinating moieties. In the first step, solid S1 in contact with anionic surfactant solutions provides the superficial self-assembly organization of the surfactants on the cationic functionalised surface. This layer would be remarkably hydrophobic with the long alkyl chains most likely pointing toward the bulk solution, which in the second step is able to extract a suitable dye (Methylene Blue) from water. The detection principle depends on the fact that the self-assembly process of the anionic surfactant is selective as a consequence of unique strong hydrophobic interactions between surfactant molecules in the monolayer formed. The final behaviour signalling the presence of anionic surfactants would be depletion of the dye solution and coloration of the solid, both visible to the naked eye. A similar protocol was used for the detection of cationic surfactants. In this case solid S2 was prepared containing sulfonate groups. S2 was obtained by reaction of silica with 3-mercaptopropyltriethoxysilane (MPTS) following the oxidation of the mercapto group to sulfonate by adding H2O2. In this case the interaction of cationic surfactants with the S2 surface results in the self-assembly of the cationic surfactants on the anionic surface. In the second step, the addition of a suitable anionic dye (i.e. Patent Blue) then leads to the signalling of the presence of cationic surfactants. S1 and S2 solids were characterised using standard solid-state techniques. A study of the response of these solids was carried out on different concentrations of anionic, cationic and neutral surfactants and in the presence of compulsory water-present anions and cations. The partial decolouration of the dye solution or the corresponding colouration of the solid was related to the concentration of the surfactants in the aqueous solution. The method comprises a novel organic-solvent-free approach for the colorimetric detection of anionic or cationic surfactants. A model was also developed able to interpret the colorimetric behaviour of the solids based on (i) surfactant adsorption on the charged surface and (ii) further extraction of the corresponding dye.

Based on the cross-sensitivity shown by certain metal electrodes for some anions in a liquid media, an array of five potentiometric electrodes (Au, Ag, Pt, Cu and Zn) has been used as an electronic tongue device for the recognition and prediction of common anions chloride, sulfate and bicarbonate in mineral waters. The recognition testing studies included measurements of potential (emf) on solutions of pure salts, mixtures of salt and some mineral waters. Predictions were performed by using partial least square. A good discrimination between different water samples by PCA analysis was found as well as an adequate prediction of the concentration of chloride and sulfate.

This paper focuses on the removal of nitro substituted polycyclic aromatic hydrocarbon compounds (NPAHs) from water using low cost synthesized zirconium phosphate mesoporous materials. These materials are lamellar type incorporating n-alkyl-(n = 12 and n = 16) trimethylamonium bromide molecules with different concentrations. For comparison of their performance as adsorbents and in the recovery of NPAH, their results were compared with commercial ENVI-18 extraction tubes and three dimensional type material incorporating hexadecyl-trimethyl ammonium bromide. The adsorption yield for the new materials were almost 100% and the recovery factors with dichloromethane as eluent was nearly 100%. Best results were obtained by preparing lamellar zirconium and titanium phosphates in the presence of n-dodecyl-trimethylammonium. This material has several environmental advantages because zirconium salts are non-toxic and their synthesis costs is relatively small.

One of the fields where the idea of developing artificial electronic mammalian sense devices might be widely applied is in food analysis. In this field, one very complex attribute yet of great importance is that of freshness. For instance, freshness is one of the most significant parameters of fish quality in most markets. The state of fish freshness can be assessed by various indicators but most of them are costly, time-consuming and lack of aptness for in situ or on site monitoring. This makes that the development of simple and undemanding systems for the evaluation of fish freshness is still an unresolved goal. Based on this demand, we focused our attention on the use of unselective sensors for the potential development of low-cost and easy-to-use devices for the estimation of freshness. After a preliminary study with a number of different electrodes, simple Au and Ag wires were used for the analysis of the evolution of sea (Sparus aurata) bream fish stored throughout time. PCA and neuronal network analyses showed that it is possible to determine the post-mortem time elapsed in minced gilthead sea bream using simple potentiometric measurements, suggesting that this method could be used for the analysis and evaluation of fish freshness. In order to somehow validate the potentiometric protocol for freshness assessment, the method has been compared with the determination of fish freshness based on the analysis of the concentration of certain bio-molecules as a function of time after the death of the fish. Among different possibilities the K1 index that simultaneously measures the variation in the ATP metabolites inosine 5′-phosphate (IMP), inosine (Ino) and hypoxanthine (Hx) was used. A remarkable correlation has been found between the K1 index determined during 7 days and the potentials of the Au and Ag electrodes.

Molecular planarity of penta-p-phenylene (P5P) and several substituted derivatives with four side chains of various lengths, including deca(ethylene glycol) groups, is discussed by considering the changes in the intensity ratio between the Raman bands recorded at 1280 and 1220 cm(-1). The intensity ratio between both bands I(1280)/I(1220) shows a small increase with the size of the substituent, indicating a high rigidity for all these compounds, even those with long oligo(ethylene glycol) side chains. This result is important given that these phenylene derivatives are versatile building blocks for the construction of nanometric tripod-shaped adsorbates for biological applications since the side chains should prevent the nonspecific interaction with proteins.

Surface-enhanced Raman spectra (SERS) of pyrimidine recorded on a silver electrode have been analyzed on the basis of a resonant Raman (RR) process involving photoexcited charge transfer (CT) states of the metal-adsorbate surface complex. The main feature of the SERS of benzene and azine derivatives is the enhancement of the totally symmetric ring stretching mode 8a due to Franck-Condon contributions related to the CT transition. Although this behavior is observed in the SERS of pyrimidine, its spectrum is also characterized by the strong enhancement of the nontotally symmetric mode 8b. This peculiar feature can be explained only by the redistribution of the Franck-Condon factors between the 8ab pair of vibrations originated by the descent in symmetry occurring when pyrimidine is bonded to silver nanoclusters. This conclusion is a new evidence of the main role of the RR-CT enhancement mechanism in the SERS of aromatic molecules and shows once again the usefulness of the methodology developed by our group in order to analyze these complex spectra.

The behaviour of the naphthoquinone derivatives 4-(4-dimethylamino-phenyl)-[1,2]naphthoquinone (L1) and 4-[4-(1,4,7,10,13-pentaoxa-16-aza-cyclooctadec-16-il)-phenyl]-[1,2]naphthoquinone (L2) as chromogenic chemosensors of metal cations and anions in acetonitrile has been studied. L1 and L2 are highly coloured receptors with a broad band centred at 534 (log e = 3.80) and 532 nm (log e = 3.86), respectively, and attributed to an intra-ligand charge transfer band involving the amine and the carbonyl groups. L1 shows a hypsochromic shift of the absorption band in the visible zone in presence of Cu2+, Fe3+ and Hg2+. Additionally, L2 suffers bleaching induced by the metal cations Pb2+ and Ba2+. In both cases, the data suggested metal cation coordination through the nitrogen atom of the aniline group. 1H NMR studies in the presence of certain metals are also in agreement with this interpretation. log K for the formation of the corresponding [M(L)]2+ complexes have been determined from nonlinear least-squares treatment of the titration profiles. Studies in the presence of anions were also carried out. In acetonitrile a chromogenic sensing of the anions HSO 4 - was observed using the metal complex Ba–L2.

A new “electronic tongue” has been developed and used for the qualitative analysis of natural waters. Both wires and conducting surfaces in thick-film technology were used as potentiometric electrodes and the emf of each electrode in contact with a certain aqueous solution was used as input signal for a PCA analysis. An array containing the electrodes; RuO2 (with resistivities of 10 � /sq and 1 M� /sq), C, Ag, Ni, Cu, Au, Pt, Al, Sn, Pb and C (graphite) were used in a first approach. To test this “electronic tongue” design, a family of different natural waters were studied. These include seven mineral waters, tap water and osmotised water. Additionally, a qualitative analysis of the different waters was performed using fuzzy ARTMAP neural networks. The final system was successfully employed for the differentiation of the above mentioned waters with a success rate higher than 93%. © 2004 Elsevier B.V. All rights reserved.

The polyazacycloalkanes, 1,4,8,11-tetra(n-octyl)-1,4,8,11-tetraazacyclotetradecane (L1), 1,4,7,10,13-penta(n-octyl)-1,4,7,10,13-pentaazacyclopentadecane (L2) and 1,4,7,10,13,16-hexa(n-octyl)-1,4,7,10,13,16-hexaazacyclooctadecane (L3) have been synthesised, characterised and the ability of these polyamines as anion receptors has been studied using them as ionophores in PVC membrane anion-selective electrodes. The PVC membranes containing L1, L2 and L3 gave a linear response in the presence of perchlorate. The EMF response characteristics of these membrane-based perchlorate-selective electrodes and the selectivity coefficients using DOS, DBP or NPOE as plasticisers have been determined. The perchlorate-selective electrodes gave anion-selectivity patterns that basically follow the Hofmeister Series, expect the ISE containing L1 and DOS as plasticiser.

A general model concerning the role of the electrode potential on the charge-transfer enhancement mechanism of SERS is proposed, justifying the existence of a parameter ‚ which reduces the effectiveness of the electrode potential in order to shift the excited charge-transfer level. This explains the observed deviation of ‚ from the unity, and allows for relating the intensity/electrode-potential (SERS -CT) profiles of similar adsorbates with the respective electron affinities. The SERS of pyridine, pyrazine and methylpyrazines have been recorded on silver, being found that the electrode potential in the maximum of the SERS-CT profiles shifts toward more negative values as the number of methylsubstituents attached to the pyrazine ring increases. This result has been explained on the basis of the relative stability of the radical anions given that a correlation between those shifts and the calculated ab initio vertical transition energies between the neutral molecules and their respective radical anions can be established. This confirms the participation of a resonant charge-transfer mechanism in the SERS as well as the usefulness of this technique to gain insight into the electronic properties of the doublet states of the here studied molecules.

The surface-enhanced Raman scattering spectra of 2,6-dimethylpyridine have been recorded on silver at different electrode potentials. The main feature of these spectra is the strong enhancement of the band corresponding to the 8a mode when the electrode potential becomes more negative. This enhancement has been discussed on the basis of a resonant charge transfer (CT) mechanism by using a methodology based on the analysis of the ab initio optimized equilibrium structures of the electronic states involved in the CT resonant process namely: the ground electronic states of the neutral molecule and its radical anion.

The new open-chain polyazaalkanes ligands L 1 , L 2 , L 3 and L 4 functionalised with one or two pyrene groups were synthesised and characterised and their potential use as selective cation and anion sensing chemosensors studied. Solution studies by potentiometric methods were carried out in the presence of the metal cations Cu 2+ and Zn 2+ in acetonitrile–water (70:30 v/v, 0.1 mol dm −3 tetrabutylammonium perchlorate, 25 °C) The results are compared with those reported for the analogous non-functionalised ligand triethylentetraamine ( tta ). The fluorescence behaviour of the ligands L 1 –L 4 has been studied as a function of the pH in the presence of the metal cations Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Hg 2+ and Pb 2+ in acetonitrile–water 70:30 v/v mixtures. The Zn 2+ and Cd 2+ cations enhance the fluorescence emission of the L 1 –L 4 chemosensors at basic pH, whereas Cu 2+ induce quenching of the fluorescence emission at acid pH. The fluorescence behaviour of L 1 –L 4 receptors was also studied as a function of the pH in acetonitrile–water 70:30 v/v in the presence of anions.

4′-[4-(Bromomethyl)phenyl]-2,2′:6′,2″-terpyridine reacts with triethylenetetraamine or tetraethylenepentaamine in CH2Cl2 to yield the ligands L1 and L2, respectively. Reaction of L1 and L2 with Ru(mtpy)Cl3 (mtpy = 4′-methyl-2,2′:6′,2″-terpyridine) in MeOH yielded, after column chromatography and precipitation with [NH4][PF6], the compounds [Ru(L1)(mtpy)][PF6]2 and [Ru(L2)(mtpy)][PF6]2. These metallo-receptors contain triethylenetetraamine or tetraethylenepentaamine recognition sites and [Ru(tpy)2]2+ cores as fluorescent signalling subunits. The fluorescent behaviour of [Ru(L1)(mtpy)]2+ and [Ru(L2)(mtpy)]2+ in the presence of metal ions and anions has been studied in MeCN:H2O (70:30 v/v) as a function of the pH.

Electrochemical studies on redox-active macrocyclic and open-chain ferrocene-containing oxa-aza or polyaza receptors were carried out in acetonitrile in the presence of protons, cations and anions. Electrochemical studies in the presence of H + , Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Hg 2+ and Pb 2+ with L 4 (1,15-diferrocenyl-2,5,8,11,14-pentaazapentadecane) and L 5 (1,4,7,10,13-penta(ferrocenylmethyl)-1,4,7,10,13-pentaazacyclopentadecane) resulted in shift of the ferrocene oxidation wave to more positive potentials with maximum shifts for L 4 in the presence of Zn 2+ and for L 5 in the presence of Ni 2+ , Cu 2+ and Hg 2+ of 80 mV. In contrast, L 1 (10-ferrocenylmethyl-1,4,7-trioxa-10-azacyclododecane), L 2 (1,8-bis[bis(ferrocenylmethylamino)]-3,6-dioxaoctane) and L 3 7,13-bis(ferrocenylmethyl)-1,4,10-trioxa-7,13-diazacyclopentadecane) show a two-wave behaviour for H + , Pb 2+ and Hg 2+ allowing the amperometric titration of these metal cations. The maximum oxidation peak shift of 290 mV was found for L 1 in the presence of Hg 2+ . Electrochemical behaviour with anions (H 2 PO 4 − , HSO 4 − , Br − and Cl − ) in acetonitrile show that L 2 and L 6 (1,8-bis(ferrocenylmethylamino)-3,6-dioxaoctane) electrochemically sense H 2 PO 4 − . For L 2 a cathodic shift of the oxidation peak of 190 mV and a shift of 346 mV to lower potential for the reduction peak was found. L 6 shows a similar behaviour. This electrochemical sense of H 2 PO 4 − was observed even in the presence of excess of other anions (HSO 4 − or Cl − ) in anion competition experiments.

Compounds L 1 and L 2 were obtained by reaction of 2-(bromomethyl)naphthalene with 1,4,10-trioxa-7,13-diazacyclopentadecane and 1,4,7-trioxa-10-azacyclododecane, respectively. These receptors contain aza–oxa crowns attached covalently to fluorescent groups. The protonation and coordination behaviour of L 1 and L 2 against metal ions has been studied in dioxane:water (70:30 v/v, 25°C, 0.1 M potassium nitrate) using potentiometric methods. All metal ions studied form complexes with L 1 and L 2 with the logarithm of the formation constants L+M 2+ =[M(L)] 2+ in the sequence Cd 2+ ≅Pb 2+ , Zn 2+ 2+ for L 1 and Zn 2+ 2+ 2+ 2+ 2+ for L 2 . The fluorescent behaviour of L 1 and L 2 was studied in dioxane:water (70:30, v/v) and in acetonitrile in the presence of Ni 2+ , Cu 2+ , Zn 2+ , Cd 2+ , Hg 2+ , Pb 2+ cations and chloride, bromide, sulfate and phosphate anions. The most significant feature is the quenching of the fluorescence produced by Cu 2+ in acetonitrile.

The selective sensing of the ATP anion in an aqueous environment over phosphate, sulfate, and chloride using a fluorescence chemosensor based on Ru(tpy)22+ cores attached to polyammonium groups is reported.

The reaction of 2,2′:6′,2″-terpyridinyl-4′-carboxaldehyde with the diamine N-methyl-1,3-propanediamine yields the terpyridine derivative containing amino groups 1-(2,2′:6′,2″-terpyridin-4′-yl)-2,6-diaza-2-methylcyclohexane (L1), whereas under similar experimental conditions the reaction of 2,2′:6′,2″-terpyridinyl-4′-carboxaldehyde with N,N-dimethylethylenediamine yields the expected 1-(2,2′:6′,2″-terpyridin-4′-yl)-2,5-diaza-5-methyl-hexa-1-ene (L2) imine and the [4′-COO-tpy][H3NCH2CH2N(CH3)2] salt (L3). The crystal structure of L3 was determined by X-ray single-crystal analysis. The structure consists of terpyridine carboxylate and protonated diamines linked together by ionic and hydrogen bonding interactions. The homoleptic complexes [Co(L1)2]2+ and [Fe(L1)2]2+ have been prepared. These contain peripheral amino groups and their interactions with protons and the anions ATP, chloride, sulphate and phosphate have been studied in acetonitrile and in THF:water (70:30 v/v) using electrochemical techniques.

Some new ferrocene-functionalized amines have been synthesized and characterized. Electrochemical and potentiometric studies have been carried out in THF: H2O (60:40 v/v) to determine protonation constants of the oxidized and “reduced” species and the oxidation potential shift between pH acid and basic. Some electrochemical studies have also been performed in CH2Cl2:MeOH mixtures. The change in the acidity properties after oxidation and the related redox potential shift after protonation are discussed.

[EN] We report herein the design, manufacture and use of a "humid electronic nose" prototype based on voltammetric techniques. It consists of an array of four working electrodes (i.e., Au, Pt, Ir and Rh) housed inside a homemade stainless steel cylinder, in contact with a fabric mesh made of nylon damped with a NaCl aqueous solution, used as the supporting humid membrane. The "humid electronic nose" was tested for the discrimination of different samples displaying different volatile compounds. The samples chosen involve aqueous solutions of different simple volatile products (i.e., ammonia, acetone, acetic acid and 6-amino-1-hexanol) and different food samples (i.e., onion, coffee and Roquefort cheese). Under working conditions, the volatile compounds from the corresponding sample were generated in the measurement chamber and were partially dissolved in the damped nylon fabric, which was in contact with the set of electrodes. It was envisioned that provided different samples offer different vapours, the application of a suitable set of pulses to the electrodes will differentiate the samples. This proof-of-concept study employed a Large Amplitude Pulse Voltammetry (LAPV) waveform. The increment for the potential steps was of 200 mV and potentials ranged from +1 to -1 V with each pulse applied for 50 ms. PCA studies from the response obtained by the "humid electronic nose" discriminated the different samples studied. The neural network Self Organized Map (SOM) was also used to analyze the electrochemical data obtained from the "humid electronic nose". © 2013 Elsevier B.V, The financial support from the Spanish Government (project MAT2012-38429-C04) and the Generalitat Valenciana (Valencian Regional Government; projects PROMETEO/2009/016 and GV/2012/094); is gratefully acknowledged.

Reaction of ferrocene-1,1′-dicarbaldehyde and propylenediamine yields the Schiff-base derivative 1,1′-(2,6-diazahepta-1,6-diene)-ferrocene (1). The molecular structure of 1 has been determined by single crystal X-ray analysis. It crystallises in the monoclinic system, space group P2 1 /c, a=13.507(3), b=9.800(2), c=10.086(2) A , β=110.81(3)°, Z=4 and V=1248.0(5) A 3 . Refinement of the atomic parameters by least-squares techniques gave a final R factor of 0.074 for 1588 observed reflections having I>2σ(I). Hydrogenation of 1 with LiAlH4 results in the parent amine 1,1′-(2,6-diazaheptane) ferrocene (2). The protonation of 2 has been investigated by potentiometry in water in the pH range 11-6. At pH lower than 6, 2 is unstable in solution. The E 1 2 potential for 2 is pH-dependent ( E 1 2 ( pH 11) = 255 , E 1 2 ( pH 6) = 435 mV ). A similar behaviour was also observed in THF:water (60:40 vol./vol.). The electrochemical behaviour for 1 and 2 has also been studied in CH2Cl2.

The reaction of ferrocenecarbaldehyde with o-phenylenediamine in the presence of p-toluenesulphonic acid results in the synthesis of N-ferrocenylmethyl-2-ferrocenyl-benzimidazole, 1, and 2-ferrocenyl-benzimidazole, 2. The molecular structure of 1 has been determined by single crystal X-ray analysis. It crystallises in the triclinic system, space group P 1 , a = 10.069(7), b = 13.625(8), c = 9.314(7) A , α = 92.75(5)°, β = 104.68(6)°, γ = 95.43(6)°; V = 1227(1) A 3 , Z = 2. An electrochemical study of 1 and 2 dichloromethane: methanol (10:1) has been carried out. 2 shows a reversible oxidation processes at Epa = 535 mV. The addition of HCl (1 equiv.) switches the oxidation potential giving a new wave at Ep a = 800 mV . 1 shows a reversible 2e− oxidation processes at Epa = 558 mV which is split into two different waves when 1 equiv. of HCl is added. The switching process is reversible for 1 and 2 and addition of base (KOH) leads to the former oxidation potential.

Ferrocenecarboxaldehyde reacts with 2-amino-benzoic acid, 2-amino-5-methyl-benzoic acid or 3-amino-2-naphthoic acid to give the corresponding Schiff-base derivatives 2-ferrocenylmethylidenimino-benzoic acid (1), 2-ferrocenylmethylidenimino-5-methyl-benzoic acid (2) and 3-ferrocenylmethylidenimino-2-naphthoic acid (3). 1, 2 and 3 are stable in the solid state but easily hydrolyze in solution. This hydrolysis has been studied kinetically in a methanol-water medium. In order to increase the stability in solution to use these compounds as ligands, the imino group from 1, 2 and 3 was reduced by NaBH4 to give the amino derivatives 2-ferrocenylmethylamino-benzoic acid (4), 2-ferrocenylmethylamino-5-methyl-benzoic acid (5) and 3-ferrocenylmethylamino-2-naphthoic acid (6). 4, 5 and 6 are stable, both in the solid state and in solution, and potential chelating NO donor ligands containing ferrocenyl groups. The protonation of 4–6 and their complex formation with copper(II) have been investigated by potentiometry in dimethyl sulfoxide (dmso)-water (80:20 wt./wt.) mixtures at 25 °C and 0.1 mol dm−3 KClO4. The molecular structure of 5 has been determined by single-crystal X-ray methods. It crystallizes in the triclinic system, space group P 1 , with a = 6.1747(7), b = 9.539(1), c = 13.511(4) A , α = 88.99(1), β = 87.00(1), γ = 82.34(1)°, V = 787.6(3) A 3 and Z = 2 . An unusual feature of the ferrocene-containing ligand 5 in its interaction with nickel(II) ions was found. Cleavage of the CN bond of the secondary amine 5 and molecular rearrangement yields the protonated tertiary amine 2-bis(ferrocenylmethyl)ammonium-5-methyl-benzoic acid perchlorate (7). Compound 7 crystallizes in the monoclinic system, space group P21/c with a = 9.702(9), b = 27.153(17), c = 22.326(6) A , β = 97.39(6)°, V = 5833(12) A 3 and Z = 8 . Typical reversible oxidation waves were found for 4–7 whereas some degree of irreversibility was detected for their parent imines.

[EN] A new selective chromo-fluorogenic probe for Fe 3+, Cr 3+ and Al 3+ is reported. Detection limits are in the ¿M range and the fluorogenic sensing ability could be observed by the naked eye when illuminated with UV-light. No response is observed with divalent cations. © 2012 The Royal Society of Chemistry., AECID (A/026355109), DGICYT (projects MAT2009-14564-C01 and MAT 2009-14564-C04-3) and Generalitat Valenciana (project PROMETEO/2009/016) are gratefully acknowledged. A.B.B. thanks MICINN for a pre-doctoral FPI fellowship.

Bi-functionalized hybrid silica nanoparticles have been synthesized, characterized and their optical emission properties in the presence of certain anions studied. The hybrid solid S1, coated with sulforhodamine B as fluorogenic signalling unit and imidazolium groups as anion coordination sites, was prepared by the simultaneous grafting of suitable derivatives of these two subunits on silica nanoparticles. For the preparation of the sensing material S2, first the surface of silica nanoparticles was grafted with (3-aminopropyl)trimethoxysilane yielding solid SN. Then, in a second step, the amino groups on the surface were transformed into the corresponding guanidinium binding sites by reaction with pyrazole carboxamidine yielding solid SG. Finally, the grafting of the sulforhodamine B derivative 1 on SG resulted in the hybrid nanoparticles S2. Acetonitrile suspensions of S1 and S2 showed typical sulforhodamine B absorption bands at ca. 550 nm. Upon excitation, an emission band at 575 nm was observed. Signalling properties of S1 and S2, in acetonitrile and acetonitrile:water 9:1 v/v mixtures, in the presence of organic (acetate, benzoate) and inorganic (F−, Cl−, Br−, CN−, NO3−, HSO4− and H2PO4−) anions were studied. S1 showed a fluorogenic response toward iodide and benzoate, whereas S2 selectively responds to dihydrogen phosphate and hydrogen sulfate., Financial support from the Spanish Government (Project MAT2009-14564-C04-01) and the Generalitat Valenciana (Project PROMETEO/2009/016) is gratefully acknowledged.

A hybrid nanoscopic capped mesoporous material, that is selectively opened in the presence of nerve agent simulants, has been prepared and used as a probe for the chromo-fluorogenic detection of these chemicals. © 2011 The Royal Society of Chemistry., Financial support from the Spanish Government (project MAT2009-14564-C04-01 and -02) and Generalitat Valenciana (project PROMETEO/2009/016) is gratefully acknowledged. I. C. thanks the UPV for her Fellowship. SCSIE (Universidad de Valencia) is gratefully acknowledged for all the equipment employed.

This communication reports, for the first time, the dependence of the SERS intensities under resonant CT conditions (SERS-CT) on the electrode potential. SERS-CT intensities have been estimated from the properties of S(0)-CT(i) transitions ranging between 200-1200 nm of selected [Ag(n)-pyridine](q) and [Ag(n)-pyrazine](q) complexes.

Quantum mechanical calculations of the ground and excited electronic states of several [Ag(n)-pyridine](q) complexes yield a linear dependence of the energies of the surface states, especially the metal-to-molecule charge transfer states, on q(eff) = q/n. This is the first theoretical approach to modelling the effect of the electrode potential on SERS.

In conjunction with quenching metal ions, silica nanoparticles carrying terpyridine coordination sites and sulforhodamine B signalling units were employed for the differential fluorometric recognition of anions. © 2011 The Royal Society of Chemistry.

A new chromo-fluorogenic sensing protocol for anionic surfactants in aqueous environments using silica functionalised nanoparticles containing imidazolium and thiol groups has been developed. © 2011 The Royal Society of Chemistry., Financial support from the Spanish Government (project MAT2009-14564-C04-01) and the Generalitat Valencia (project PROMETEO/2009/016) is gratefully acknowledged. E. C. and C. G. thank the MICINN and the UPV for fellowships.

A series of complexes of formula {Ni(Me6[14]aneN4)X2| (Me6[14]aneN4) = C-meso-5,5,7,12,12,14-hexamethyl-1,4,-8,11-tetraazacyclotetradecane and X = N3(1), NCO (2), NCS (3), AcO (4) or I (5) has been synthesized. The crystal structure of (5) has been determined by X-ray diffraction methods. The nickel atom is surrounded by a square-planar array of nitrogen atoms, giving a low-spin complex. The macrocyclic ligand shows the most stable conformation, the six-membered rings exhibiting the chair form while the gauche conformation is adopted by the five-membered rings. Spectroscopic and magnetic data for (1)–(4) are consistent with octahedral coordination around the nickel atom, which is achieved by four N atoms of the macrocyclic ligand in a single plane and by two azido-N (1), cyanato-N (2), thiocyanato-N (3) and carboxylato-O (4) groups occupying the axial positions. An electrochemical study of the oxidation of (1)–(5) has been carried out in nonaqueous solvents and the prospects of synthesis of the corresponding nickel(III) species are discussed in the light of the electrochemical data.

Ferrocenecarboxaldehyde reacts with 2-amino-benzoic acid in benzene to give the Schiff base derivative 2-ferrocenyl- methylidenimino-benzoic acid (η5-C5H5)Fe[(η5-C5H4)CH NC6H4COOH] (1). 1 is stable as a solid but easily hydrolyzes in solution. Selective hydrogenation of the imine group can be performed using NaBH4 to obtain the parent amine (η5- C5H5) Fe[(η5-C5H4)CH2NH& z.sbnd;C6H4COOH]. (2). The molecular structure of 2 has been determined by single-crystal X-ray methods. It crystallizes in the space group P21/c, a=11.077(9), b =7.430(2), c=19.194(9) A, β=111.02(4)°, V=1474(2) A3, Z=4. Refinement of the structure gave final R factor of 0.038 (Rw=0.035) for 1106 unique reflections having Fo2>2.8σ(Fo2). 2 is stable both in the solid state and solution, and a potential chelating N,O-donor ligand containing a ferrocenyl group. A one-electron oxidation process was found by cyclic voltammetry (0.1 M NBun4PF6, CH2Cl2) for 1 and 2 at 0.74 and 0.51 V, respectively.

The electrochemical behaviour of a series of monomeric N,N′-bis(substituent)oxamidato copper(II) complexes of formula Na2[Cu(3,5,3′,5′-X4obbz)]·4H2O [X = Cl (1), Br (2), I (3) and obbz = oxamidobis(benzoato)], Na2-[Cu(obbz)]·4H2O (4), Na2[Cu(5,5′-Me2obbz)]·4H2O (5), Na2[Cu(4,5,4,5′-(MeO)4obbz)]·4H2O(6),Na2[Cu(obp)]· 3.5H2O (7) (obp = oxamidobis(propionato)) and Na2[Cu(pba)]·6H2O (8), [pba = propylenebis(oxamate)] has been investigated by cyclic voltammetry, rotating disk electrode and coulometry in water and dimethylsulphoxide (dmso) solutions. NaNO3 (0.1 M) and n-Bu4NPF6 (0.1 M) were used as supporting electrolytes in H2O and dmso respectively, all solutions being thermostatted at 25 °C. In aqueous solution, the complexes show an oxidation peak ranging from 1.19 to 0.86 V (values referred to the s.c.e.), the corresponding reduction being unobserved, even at high scan rates. In dmso, all the complexes exhibit only one oxidation peak ranging from 0.86 to 0.51 V, the corresponding reduction being observed for all of them except for (3). The oxidation potentials are strongly dependent upon the nature of the N,N′-substituent of the oxamide. The copper(III)-assisted hydrolysis of the oxamidate ligand is analysed in terms of the lack of planarity of the oxamidate ligand induced by the steric effect of the halogen substituent in the 3-position on the phenyl rings. The influence of the nature of the solvent was also studied.

The interpretation of the infrared and Raman spectra of poly(p-phenylene ) in the pristine and doped states is presented as the result of lattice dynamic calculations and using the Effective Conjugation Coordinate theory. The conformational properties of the dimer biphenyl and some derivatives are discussed with the main aim of analysing the validity and limitations of semiempirical calculations.

The fluorescent behaviour of the polyazacycloalkane containing naphthyl groups 1,4,8,11-tetrakis(naphthylmethyl)-1,4,8,11-tetraazacyclotetradecane (L 1 ) and its Cu 2+ complex in the presence of anions are compared in aqueous environment (THF:water 70:30 v/v, 0.1 mol dm −3 tetrabutylammonium perchlorate, 25°C). The emission fluorescent intensity of the L 1 –Cu 2+ system is selectively enhanced in the presence of sulfate at acid pH.

Mesoporous amino-functionalised solids containing certain dyes have been used as suitable anion hosts in displacement assays for the colorimetric signalling of phosphate in water. Amoros del Toro, Pedro Jose, Pedro.Amoros@uv.es

Hybrid mesoporous systems containing a gate-like ensemble functionalised with imidazolium groups and a dye are used for the selective colorimetric sensing of long-chain carboxylates. Amoros del Toro, Pedro Jose, Pedro.Amoros@uv.es

[EN] Pyrylium-containing mesoporous materials have been used for the chromo-fluorogenic sensing of biogenic amines in an aqueous environment., We thank the Ministerio de Ciencia y Tecnología (MAT2003- 08568-C03-02) for support. F.S. is thankful for a Ramón y Cajal contract. B.G.A. thanks the Generalitat Valenciana and M.C. thanks the Caja de Ahorros del Mediterraneo for a Doctoral Fellowship. A.B.D. thanks the Alexander-von-Humboldt Foundation for a Research Fellowship.

A chromogenic reagent for cyanide determination in water based on the reaction of this anion with a squaraine derivative functionalized with ether chains has been developed.

The 1,3,5-triarylpent-2-en-1,5-dione group selectively undergoes cyclisation and changes its colour from yellow to magenta upon coordination of Hg2+ on a remote site.

The potential toxicity of pesticide residues in drinking water has meant a rigid regulation for the appearance of these pollutants. Thus, in this work, we developed a new immunosensor for atrazine detection. We focused on the optimisation of the antibody immobilisation method on sensor surface for the enhancement of the biosensor sensitivity. First, with site-directed immobilisation of rabbit anti-atrazine antibodies using goat anti-rabbit immunoglobulin, a detection limit of 0.5 ng/mL was obtained. This value is 20 times lower than the detection limit obtained with non-oriented antibodies. The second way to improve immunosensor sensitivity consisted of the addition of carbon nanotubes (CNT). As result of using these CNT, detection limit has been improved again from 0.5 ng/mL to 100 pg/mL., This work was financially supported by the PCI cooperation project between Spain and Tunisia.

A new colourimetric and fluorimetric method for fluoride determination in aqueous samples based on the specific reaction between fluoride and silica has been developed and applied on real samples.

Silica nanoparticles containing polyamines and thiol groups have been used as probes for the selective detection of Tetryl. © 2011 The Royal Society of Chemistry., Financial support from the Spanish Government (project MAT2009-14564-C04-01) and Generalitat Valencia (project PRO-METEO/2009/016) is gratefully acknowledged. Y.S. is grateful to the Spanish Ministry of Science and Innovation for a grant.

[EN] The inclusion of squaraine (SQ) dye I into the supercages of zeolite Y (structure code FAU) with a SiO(2)/Al(2)O(3) ratio of 30 (Z30) through a two-step ship-in-the-bottle approach is reported, resulting in the squaraine-containing hybrid material Z30-SQ. Attempts to use the same synthetic procedure on sodium and ammonium Y zeolites were unsuccessful, stressing the importance of the presence of Bronsted acid centres in the Z30 zeolite. The reflectance spectra of Z30-SQ show a maximum in the typical squaraine monomer region at 618 nm and a shoulder at 570 nm. Spectral analyses revealed that the major species are SQ dimers and (tightly adsorbed) SQ monomers and SQ aggregates are only formed to a minor degree. The emission spectrum of Z30-SQ shows a single band at 669 nm. The sensory performance of this material was tested in the presence of volatile propylamine and propylthiol and other volatile organic compounds (acetone, ethanol, dichloromethane, hexane, acetonitrile, ethyl acetate, ethyl ether and acetic acid). The blue Z30-SQ material reacts with the thiol and amine derivatives, resulting in the bleaching of the solid and disappearance of the absorption band in the visible region, but does not undergo spectroscopic changes in the presence of other volatile organic compounds (VOCs). Whereas the reaction with propylamine is irreversible, a partial reversibility was found in the presence of the thiol. Theoretical investigations of the reactivity of I with several VOC molecules at the semi-empirical level reproduced well the experimentally observed reactivity., Financial support from the Spanish Government (project MAT2009-14564-C04-01), the Generalitat Valencia (project PROMETEO/2009/016) and the Innovationsfonds (BAM/Bundesministerium fur Wirtschaft und Technologie) is gratefully acknowledged. J.V.R.L. thanks Generalitat Valenciana for a postdoctoral fellowship.

Chromogenic cyanide recognition in water was achieved by the use of a hydrophobic dye in micellar containers.