Search

Aryl azides photochemistry is strongly dependent on the substituent relative position, as has been studied by time resolved resonant Raman (TR3) spectroscopy for 4-methoxyphenyl azide and its isomer 3-methoxyphenyl azide. When irradiated at 266 nm, the former results in 4,4’-dimethoxyazobenzene whereas the latter forms 1,2-didehydroazepine. It is proposed that the key step of the reactions is the formation of a nitrene derivative. Recently, it has been proposed by us that nitrenes might have a relevant role in the Surface-Enhanced Raman Scattering (SERS) of p-aminothiophenol, however, the molecular mechanism is not well known in neither of these cases. Therefore, we studied the photodecomposition of 4-methoxyphenyl azide using multiconfigurational self-consistent field methods (MC-SCF) with the CAS-SCF and MS-CASPT2 approximations and calculated the resonant Raman spectra of the relevant species using a multi-state version of Albrecht’s vibronic theory. The results propose that the reaction follows a two steps sequence after irradiation at 266 nm: an intersystem crossing 21A’/23A’’ which decays through a 21A’/21A’’ conical intersection producing molecular nitrogen and triplet 4-methoxyphenyl nitrene in its ground state. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.

The differences between alternative approaches for quantifying the complex effect of the electronic structure of charged metal–molecule hybrids in SERS (the so-called chemical enhancement mechanism) are highlighted. The discussion is focussed on the predictions obtained by using different methodological tools for modelling the role of the electrode potential in the SERS relative intensities. Finite electric fields are used in the commented paper for this purpose, but we have found some inconsistences in the results and the method for calculating the Raman intensities is not made sufficiently clear, which prevents the assessment of the results.

Gold nanoparticles (Au NPs) are widely used today in a broad range of applications like electronics, sensors, catalysis and especially in biomedicine. However, the increase in their use has raised concerns about the possible interactions in vivo and the unexpected responses inside humans and other living organisms. Analytical tools that are able to detect their presence in biological samples and also provide information about the presence of dissolved metal ions inside biological samples are, therefore, urgently needed for a proper understanding of the behaviour of these materials. In this work, an HPLC-ICP-MS technique for the determination of Au NPs was adapted to the analysis of tissues from Wistar rats after intraperitoneal injection of 10 nm Au NPs. This technique allows the detection of Au NPs and low-molecular Au species, permitting the detection and monitoring of potential degradation processes. Alkaline and enzymatic digestions were tested to solubilize the particles and to verify their stability during the extraction process. Enzymatic digestion with proteinase K over 14 h was found to be suitable for the extraction of the Au species with recovery rates of about 91%. Finally, the method was applied to the analysis of liver and spleen samples. Significant abundances of low-molecular Au species were detected (around 30%). This observation suggested that a degradation process played a pivotal role during the transport and accumulation of Au NPs that were intraperitoneally injected into Wistar rats.

Manufactured TiO2 nanoparticles (TiO2 NPs) are nowadays widely present in products accessible to the mass market like paints, cosmetics or sunscreens. Despite the great increase in the use of these nanoparticles, until now their potential effects on the environment and biological systems have not been sufficiently studied. Reliable analytical methods are therefore required for better characterization of these emerging materials. We suggest the hyphenation of inductively coupled plasma-mass spectrometry (ICP-MS) with a separation technique like sedimentation field-flow fractionation (SdFFF) to obtain information related to the size and state of agglomeration of the investigated nanoparticles. In this work, initial experiments related to the on-line coupling of SdFFF to inductively coupled plasma-tandem mass spectrometry (ICP-MS/MS) have been conducted allowing the detection and separation of TiO2 NPs. The application of the ICP-MS/MS technology using a NH3 mass shift mode allowed the removal of the different molecular and isobaric interferences that complicate the reliable detection and quantification of Ti. Under optimised conditions, the achievable instrumental detection limits in matrix solutions were below 10 ng L−1 of Ti. The separation parameters of the SdFFF system were optimized using two commercially available model TiO2 NPs (nominal sizes: 21 and 50 nm). These materials were characterised concerning hydrodynamic diameters and the state of aggregation also using a multiangle light scattering (MALS) analysis detector. A transmission electron microscopy (TEM) technique was also applied to confirm the sizes and the shapes of the TiO2 NPs as well as the presence of aggregates. To demonstrate the applicability of the combination of SdFFF and ICP-MS/MS for the detection of TiO2 NPs at trace levels as well as to gain information about their hydrodynamic diameter and agglomeration state, the optimized method has been applied to the analysis of real water samples from a local lake in Germany.

DFT calculations predict that plasmon-like excitations in small metal clusters are able to selectively modify the relative intensities of specific SERS bands of adsorbed molecules. These electronic resonances provide new kinds of SERS selection rules which can explain the huge enhancement of mode 9a of pyridine in the spectra recorded at negative electrode potentials.

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.

A polyazacycloalkane containing naphthyl groups, 1,4,8,11-tetrakis(naphthylmethyl)-1,4,8,11-tetraazacyclotetradecane (L1), and the azaoxa cycloalkane receptors containing anthracenyl groups, 7,13-bis(anthracenylmethyl)-1,4,10-trioxa-7,13-diazacyclopentadecane (L2) and 10-anthracenylmethyl-1,4,7-trioxa-10-azacyclododecane (L3), have been synthesized and their activity as fluorescent chemosensors studied towards the metal cations Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ in THF–water (70∶30 v/v, 0.1 mol dm−3 tetrabutylammonium perchlorate, 25 °C) for L1 and 1,4-dioxane–water (70∶30 v/v, 0.1 mol dm−3 potassium nitrate, 25 °C) for L2 and L3. The crystal structure of the complex [Cd(L1)(Cl)][PF6] has been determined by X-ray single crystal procedures. The co-ordination geometry about the cadmium atom is near square pyramidal with the ligand showing a conformation with the four naphthylmethyl groups pointing above the N4 plane. Potentiometric experiments in THF–water for L1 in the presence of Cu2+, Hg2+ and Pb2+ and in 1,4-dioxane–water for L2 in the presence of Cu2+, Zn2+, Cd2+, Hg2+, Pb2+, and L3 with Cd2+ and Pb2+ have also been carried out. All metals form stable complexes with L1, L2 and L3 with stability constants for the formation of the [M(L1)]2+, [M(L2)]2+ and [M(L3)]2+ species in the sequence Pb2+

Macrocyclic ligands L1–L4 containing biphenyl units have been synthesized. Potentiometric and voltametric studies in the presence and the absence of transition metal cations have been carried out. The relationship between the conformation of the ligand and oxidation states has been also considered. The crystal structure of [HgL2(CN)2]·2Hg(CN)2 has been elucidated by X-ray diffraction techniques.

The interaction of the ferrocene-functionalised polyaza receptor 1,4,8,11-tetrakis(4-ferrocenyl-3-azabutyl)-1,4,8,11-tetraazacyclotetradecane (L1) with sulfate, phosphate and ATP has been studied potentiometrically in THF–water 70∶30 v/v (0.1 mol dm–3 tetrabutylammonium perchlorate, 25 °C). The molecular structure of the free receptor has been determined by single-crystal X-ray procedures. An electrochemical study on L1 as a function of the pH has been carried out in THF–water 70∶30 v/v in the presence of the sulfate, phosphate and ATP anions. The potential use of L1 as an anion sensing receptor is discussed in terms of the electrochemical and potentiometric data and its behaviour is compared with those of related redox-active polyammonium receptors.

A new family of aza-oxa open-chain and macrocyclic molecules functionalised with ferrocenyl groups have been synthesized and characterised. The crystal structures of the [HL1][PF6], [H2L3][PF6]2, [H2L4][PF6]2 and [H2L5][PF6]2 salts have been determined by single crystal X-ray procedures {L1 = 10-ferrocenylmethyl- 1,4,7-trioxa-10-azacyclododecane, L3 = 7,13-bis(ferrocenyl)-1,4,10-trioxa-7,13-diazacyclopentadecane, L4 = 1,8-bis[bis(ferrocenylmethylamino)]-3,6-dioxaoctane, L5 = 1,8-bis(ferrocenylmethylamino)-3,6-dioxaoctane}. They consist of cationic protonated amines linked via ionic interactions with hexafluorophosphate anions. Additionally hydrogen-bonding interactions have also been found. The receptors have been designed to promote discrimination, using electrochemical techniques, between toxic heavy metal ions such as Hg2+ over other commonly water present cations in aqueous environments. The presence in the receptors of oxygen and nitrogen donor atoms has been used to control the selectivity of large metal ions over small ones. Potentiometric and electrochemical studies have been mainly carried out to find pH ranges of selective electrochemical recognition. Potentiometric titrations were carried out in water (25°C, 0.1 mol dm-3 potassium perchlorate) for L1 and L2 [1,1′-(5,8-dioxa-2,11-diazadodecane-1,12-diyl)-ferrocene] and in 1,4-dioxane-water (25°C, 0.1 mol dm-3 potassium nitrate) for L3 and L5 with Ni2+, Cu2+, Zn2+, Cd2+, Pb2+ and Hg2+. All receptors show larger stability constants with Hg2+ than with the remaining metal ions studied. This is especially so for L1 and L2. The receptors L1, L2 and L5 are able electrochemically and selectively to sense the presence of Hg2+, whereas maximum electrochemical shifts are produced in L3 upon addition of Pb2+. Of importance is the large and selective electrochemical shift monitored in water for L2 and Hg2+ with an anodic displacement of the oxidation potential of ca. 130 mV which is one of the largest shifts ever reported in electrochemical cation sensing in water using related receptors. A good agreement has been found between potentiometric and electrochemical results. Selective electrochemical response against Hg2+ appears to be associated with (i) pH ranges of selective complexation or (ii) the existence of strong predominant receptor-metal complexes in a wide pH range. Additionally the electrochemical behaviour of receptors L1 and L2 in the presence of metal ions can be roughly predicted from potentiometric data. The stability constants of the complexes between L1 and Cu2+, Cd2+, Pb2+ and Hg2+ were also determined in the presence of Cl-. Whereas there is no important change in the stability constants of the L-H+-M2+ systems when M2+ = Cu2+, Cd2+ or Pb2+, there is a decrease of the co-ordination ability of L1 towards Hg2+. This is also reflected in electrochemical studies which demonstrate that [Hg(L1)]2+ electrochemically sense Cl- at pH 7. To the best of our knowledge this is the first time it has been shown that metal complexes functionalised with ferrocenyl groups can electrochemically sense anions.

New open-chain polyazaalkane N-terminal ferrocene-functionalised receptors, L1, L2 and L3, have been synthesized and characterised and their potential use as selective anion and cation sensing receptors in aqueous solution investigated. Solution studies by potentiometric methods have been carried out in the presence of H+ and Cu2+ in water (25 °C, 0.1 mol dm–3 KNO3). The results have been compared with those of the analogous non-functionalised receptors triethylenetetramine (L4), tetramethylenepentamine (L5) and N,N″‴-dimethylpentaethylenehexamine (L6). Compounds L1–L3 form both mono- and di-nuclear complexes with Cu2+. The electrochemical responses as a function of the pH in the presence of the Ni2+, Cu2+, Zn2+, Cd2+ or Pb2+ cations in water and the ATP, phosphate, sulfate and nitrate anions in thf–water (7∶3 v/v, 25 °C, 0.1 mol dm–3 [Bun4N][ClO4]) for L1, L2, L3 and for 1,4,7,10,13,16-hexaferrocenyl-1,4,7,10,13,16-hexaazacyclooctadecane (L7) in 1,4-dioxane–water (7∶3 v/v, 25 °C, 0.1 mol dm–3 KNO3) have also been determined. The studies have been directed to determine the pH ranges of selectivity in the electrochemical recognition of cations and anionic guests, pointing out the ability of molecules L1–L3 and L7 to act as selective anion-sensing or cation-sensing receptors. The anion ATP can be selectively detected using the L2 receptor in the presence of the competing anions phosphate and nitrate.

Potentiometric and electrochemical studies have been carried out in THF–H 2 O (60:40 v/v) and H 2 O on several ferrocene-containing pH-responsive molecules and the acidity constants of the reduced species (K m ), the ‘oxidised’ species (K m n ) and the maximum oxidation potential shift due to the binding process of L with protons (ΔE) have been determined. From these values, and ΔE data in MeCN, MeCN–H 2 O (80:20 v/v), THF–H 2 O (80:20 v/v) and H 2 O, an empirical equation based on a Coulomb charge model, is obtained which accounts for the maximum oxidation potential shift as a function of the charge of the oxidised electroactive framework, the charge of the substrate, the number of electrons involved in the electrochemical process, the number of redox-active units, the distance between the redox-active groups and the substrate and the macroscopic relative permittivity of the medium.

The vinylogous α-pyridone 1,2-dihydro-1-(4-methoxyphenyl)-2-(4-oxocyclohexa-2,4-dienylidene)-4,6- diphenylpyridine 3 was prepared and its solvatochromic behaviour in several solvents recorded and compared to that of its γ-isomer 1. The relative behaviour of these dyes, which differed from that of other solvatochromic vinylogous α/γ-pyridones, could be reproduced by a previously described theoretical model.

New open-chain tetraamines containing ferrocene, 1,1′-bis(5-methyl-2,5-diazahexyl)ferrocene L1 and 1,1′-bis(2,5-diazahexyl)ferrocene L2, have been synthesized and characterized. Their protonation behaviour has been studied by potentiometric titrations in water (0.1 mol dm–3 KNO3, 25 °C). The co-ordination ability of L1 towards the divalent metal ions Ni2+, Cu2+, Zn2+, Cd2+ and Pb2+ has also been studied. It forms both mono-and bi-nuclear complexes with Ni2+, Cu2+, Zn2+ and Cd2+ whereas only mononuclear species were found for Pb2+. The electrochemical behaviour of L1 has been studied in CH2Cl2 and water, E½ is pH-dependent and from the E½vs. pH curve the protonation constants of oxidized L1(FeIII) were determined. Similar electrochemical experiments were carried out for L1–H+–M2+ systems. The good agreement between the E½vs. pH and z vs. pH curves (z= average charge calculated from potentiometric data) appears to suggest that the ferrocene–substrate interaction is mainly electrostatic.

Reaction of N,N′,N″,N‴-tetrakis (2-aminoethyl)-1,4,8,11-tetraazacyclotetradecane (taec) with ferrocenecarbaldehyde and further reduction with LiAlH4 resulted in the synthesis of the redox-active receptor N,N′,N″,N‴-tetrakis(4-ferrocenyl-3-azabutyl)-1,4,8, 11-tetraazacyclotetradecane (tfabc). The protonation behaviour of tfabc and its complex formation with CuII, ZnII and CdII have been studied in tetrahydrofuran–water (70 : 30 v/v)(0.1 mol dm–3 NBut4ClO4, 25 °C). The potentiometric and electrochemical data indicate the formation of 1 : 1 and 1 : 2 (tfabc: M2+) stoichiometries. The E½ values for tfabc shift as a function of the pH from 389 (pH 10) to 482 mV (pH 2.5) and E½vs. pH curves for the tfabc–H+–M2+ systems (M = Cu, Zn or Cd) show that tfabc electrochemically recognises the presence of copper(II) selectively at pH < 5. The shift of E½ appears to be caused by electrostatic forces and the E½vs. pH curves can be predicted in terms of the distribution diagrams of the tfabc–H+–M2+ systems.

The thermolysis of tetranitromethane has been studied by the semiempirical methods AM1 and PM3 from the stable molecules to the final products NO, NO2, CO and/or CO2. In agreement with the experimental data, the rate-limiting step has been found to be the monomolecular activation of a C—N bond, which can proceed either towards dissociation or towards isomerization to nitrite. A detailed reaction mechanism is proposed and every transition state has been identified. In addition to using the usual criteria to characterize transition states, we have found it useful to calculate their normal coordinates, because the coordinate related to the imaginary vibrational frequency provides insights into which vibrational degree of freedom becomes a translational one. The activation energy and the pre-exponential factor in the rate constant have been computed and found to be in excellent agreement with experiment.

By reaction of N,N′-ethylenebis(ferrocenylmethylamine)1 with tetracyanoethylene in dichloromethane the yellow compound 2-dicyanomethylene-1,3-bis(ferrocenylmethyl)-1,3-diazolidine 2 can be isolated. The single-crystal structure of 2 has been determined. It crystallizes in the non-centrosymmetric trigonal space group P3221, a= 12.255(2), c= 13.831(7)A, Z= 3. Refinement of the atomic parameters by least-squares techniques gave a final R factor of 0.038 (R′= 0.034) for 1782 observed reflections having I > 2.5δ(I). Anomalous values of the bond distances and the vinyl carbon chemical shift in the 13C NMR spectrum of 2 are explained on the basis of a polarization due to a combination of the electron-donating behaviour of the nitrogen atoms with the electron-acceptor character of the cyano groups in the dicyanovinyl diamine fragment. The non-linear optical properties were investigated. A second harmonic generation signal for 2 was detected by powder techniques with a low efficiency. Electrochemical experiments in dimethyl sulfoxide revealed a two-electron diffusion-controlled oxidation process according to two consecutive one-electron steps involving the two ferrocenyl fragments the potentials of which are separated by 43 mV. A comproportionation constant Kc of 5.3 was found by differential pulse voltammetry, indicating that the mixed-valence species [FeIIIFeII]+ is basically not stabilized.

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.

Raman and surface-enhanced Raman scattering (SERS) of 5-fluorouracil (5-FU) have been recorded under several experimental conditions. SERS spectra have been analysed according to a resonant charge-transfer (CT) mechanism similar to a resonance Raman (RR) process, involving the photoinduced transfer of an electron from the Fermi level of the metal to vacant orbitals of the adsorbate (SERS-CT). In order to detect the enhancement mechanism and to identify the chemical species that give rise to the spectra, the theoretical SERS-CT intensities for the dienolic and diketo forms, and its respective N1 and N3 deprotonated anions (5-FU(-)), have been calculated and compared with the experimental results. In this way, the presence of N1 deprotonated anion is confirmed by SERS given that the calculated SERS-CT intensities predict the selective enhancement of the band at ca. 1680 cm(-1) in agreement with the experiment. Therefore, the metal-to-adsorbate CT process involves the transient formation of the respective radical dianion (5-FU (2-)), which is new evidence of the relevance of the CT enhancement mechanism in SERS.

Silica nanoparticles functionalized with chromogenic spirobenzopyran and thiourea subunits show selective colour changes in the presence of certain long-chain carboxylates.

A chromogenic chemosensor for selective pyrophosphate sensing in aqueous environments has been developed using silica functionalised surfaces.

The ability of the new cyclic aza-oxa redox-active receptor N-ferrocenylmethyl-1,4,7-trioxa-10-azacyclododecane to selectively and electrochemically recognize Hg2+ in water over other commonly water-present metal ions is reported.

An easy model which allows to calculate protonation constants in polyamines containing n equivalent or near equivalent protonation sites from simple molecular analysis is reported.

The redox-active polyazacyloalkane 1,4,8,11-ferrocenylmethyl-1,4,8,11-tetraazacyclotetradecane L 1 is a versatile receptor for the quantitative electrochemical determination of metal ions (Cu 2+ , Zn 2+ , Cd 2+ ) and ATP in aqueous solution.

A number of functionalised mesoporous solids containing anchored anthrylmethylamine groups have been prepared using different co-hydrolysis or grafting synthetic routes. The solids have been characterised using standard solid-state techniques. Solids with a low loading of the anthrylmethylamine probe show typical well defined and structured emission bands centred at ca. 415 nm. Addition of ATP to suspensions of these solids at pH 2.8 resulted in a quenching of the anthracene emission. These solids showed a cooperative effect that resulted in quite a remarkable improvement in ATP response with respect to the free anthrylmethylamine probe in solution. Certain prepared solids showed a remarkable detection limit for ATP detection in the micromolar range. An equation based on a Langmuir-type analysis has been developed and used to obtain binding constants (adsorption constants) for the interaction of the solids with ATP and with some related anions. Some other solids containing larger amounts of anthrylmethylamine groups have also been prepared. In these cases a dual monomer–excimer fluorescence emission was observed. ATP addition to these solids resulted in an enhancement of the excimer emission band.

The use of a subphthalocyanine derivative as a selective chromo-fluorogenic reporter for the anion cyanide in mixed aqueous solutions is reported.

A remarkable enhanced response towards the hydrophilic anion sulfate using plasticized PVC membranes containing the ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate and a polyazacycloalkane derivative as ionophore has been found.

A sensory polymeric material for the colorimetric sensing of cyanide in water has been developed based on the reactivity of this anion with the pyrylium cation.