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Copper(II) (cupric) and copper(I) (cuprous) azide are both very powerful primary explosives with good thermal stabilities. However, both suffer from extreme sensitivities, which makes them unsuitable for any application. One brilliant concept for the synthesis of new ecofriendly, non-water soluble, and very powerful primary explosives is the assembly of ligands in the coordination sphere of copper(II) azide. Blocking of possible coordination sites through endothermic azoles allows the desensitization of copper(II) azide and leads to compounds with manageable sensitivities. 13 different nitrogen-rich tri- and tetrazole derivatives were used for the synthesis of energetic copper(II) azide complexes. The water insoluble compounds are highly promising candidates for the replacement of lead and perchlorate containing primary explosives. For the characterization, the complexes were analyzed by single crystal X-ray diffraction, elemental analysis (EA), infrared (IR) spectroscopy, and differential thermal analysis (DTA) measurements with heating rates of 5 °C min−1. The bulk material purity of selected complexes was confirmed by X-ray powder diffraction. The sensitivities toward impact (IS), friction (FS), and electrostatic discharge (ESD) of all synthesized compounds were tested and determined according to BAM (Bundesanstalt fur Materialforschung und -prufung) standards. The most promising compounds were investigated in copper shell initiation experiments with PETN as main charge.

Improvised explosive devices (IEDs) are constructed from easily obtainable ingredients that are often unregulated and difficult to trace. Salts of the oxyhalide perchlorate are frequently used as oxidisers in IEDs and in commercially available munitions, thus a reliable detection is needed to aid forensic investigations and the tracing of environmental ground or surface water contamination. We introduce the nematode Caenorhabditis elegans as a biosensor for the presence of perchlorate, a promising alternative to the costly, technically challenging and time-consuming current perchlorate detection methods. Perchlorate uptake dynamics in C. elegans were first validated using ion exchange chromatography followed by assessing the effects of perchlorate on key life-point indices to verify the suitability of the nematodes as a forensic biosensor. Whole genome microarrays and qPCR analyses established that a set of immune and stress response genes were enriched during perchlorate exposure. A nematode strain (agIs219) containing an integrated copy of the significantly overexpressed t24b8.5 gene promoter followed by a GFP reporter gene was shown to fluoresce in a perchlorate dose dependent manner with a limit of detection (LOD) of 0.5 mg mL−1. Whilst chemicals commonly used in the construction of IEDs did not induce fluorescence, exposure to other oxyhalides did, highlighting the presence of possible shared stress response pathways. Burnt wire sparklers containing potassium perchlorate elicited fluorescence while other non-perchlorate containing post-blast explosion matrices did not. This demonstrates how C. elegans can be used to screen for perchlorate at environmental hotspots, an optimization, possibly with other target transgenes, is required to enable the detection of perchlorate at concentrations below 0.5 mg mL−1.

We report a direct single-electron oxidation of methylenecyclopropanes (MCPs) for the rapid construction of 4-aryl-1,2-dihydronaphthalene derivatives by merging visible light photoredox catalysis and cobalt catalysis. In MeCN with Et3N·3HF (1.0 equiv.), the fluorination of MCPs can be realized in the presence of 9-mesityl-10-methylacridinium perchlorate and Co(dmgH)2PyCl, affording fluorinated 4-aryl-1,2-dihydronaphthalene derivatives in moderate yields. In MeCN/HFIP (7 : 3), 4-aryl-1,2-dihydronaphthalene derivatives were obtained in good yields through a MHAT process under similar conditions.

Self-assembly of silver(I) perchlorate with a C3-symmetric tridentate N-donor ligand produces stable crystals with open channels via catenation of 1D ladder-type coordination polymers. The open-channel crystal shows both unprecedented mixture and temperature effects on the adsorption and separation of o-, m-, and p-xylene isomers in a single-crystal-to-single-crystal (SCSC) mode. o-Xylene is not adsorbed into the channel at 5 °C, but is inserted into the channel at room temperature. In particular, the 1 : 1 mixture of o- and m-xylene was adsorbed into the channel in the 1 : 1 mole ratio via intermolecular weak interactions at 5 °C. In addition, the porous crystals are a practical template for structural determination of small liquid hydrocarbons in the SCSC state.

Two new tetranuclear compounds [Cu4(cis-1,4-chdc)2(2,2′-bpy)4(H2O)4]·4(ClO4) (1) and [Cu4(cis-1,4-chdc)2(2,2′-bpy)4(μ2-OH)2]·2ClO4·2H2O (2) [1,4-H2chdc = 1,4-cyclohexanedicarboxylic acid, 2,2′-bpy = 2,2′-bipyridine] have been prepared by stirring copper(II) perchlorate hexahydrate [Cu(ClO4)2·6H2O] with 2,2′-bpy and the sodium-salt of 1,4-H2chdc. The compounds are formed in a one-pot crystallization and are visibly distinct in colour with dark blue and sky blue appearances, respectively, for 1 and 2. Both compounds have been characterized by elemental analysis as well as single crystal X-ray diffraction (SCXRD) techniques. Interestingly, both the compounds show significant DNA binding affinity with ctDNA and these experimental findings are further corroborated by a docking study. However, compound 1 with a higher cationic charge exhibits a better DNA binding affinity compared to 2.

The synthesis of six 2,6-di(pyrazol-1-yl)pyridine derivatives bearing dithiolane or carboxylic acid tether groups is described: [2,6-di(pyrazol-1-yl)pyrid-4-yl]methyl (R)-lipoate (L1), 2-[(2,6-di(pyrazol-1-yl)pyridine)-4-carboxamido]ethyl (R)-lipoate (L2), 2-[(2,6-di(pyrazol-1-yl)pyridine)-4-carboxy]ethyl (R)-lipoate (L3), N-([2,6-di(pyrazol-1-yl)pyrid-4-ylsulfanyl]-2-aminoethyl (R)-lipoamide (L4), 2-[(2,6-di(pyrazol-1-yl)pyridine)-4-carboxamido]acetic acid (L5) and 2-[(2,6-di(pyrazol-1-yl)pyridine)-4-carboxamido]propionic acid (L6). The iron(ii) perchlorate complexes of all the new ligands exhibit gradual thermal spin-crossover (SCO) in the solid state above room temperature, except L4 whose complex remains predominantly high-spin. Crystalline [Fe(L6)2][ClO4]2·2MeCN contains three unique cation sites which alternate within hydrogen-bonded chains, and undergo gradual SCO at different temperatures upon warming. The SCO midpoint temperature (T1/2) of the complexes in CD3CN solution ranges between 208-274 K, depending on the functional group linking the tether groups to the pyridyl ring. This could be useful for predicting how these complexes might behave when deposited on gold or silica surfaces.

Several energetic salts of the 5-amino-3-methyl-1,2,3-oxadiazolium cation were synthesized and characterized. Structures are confirmed by IR, 1H and 13C NMR spectroscopy, and X-ray crystallography. The perchlorate salt was thermally stable, with a crystal density of 1.826 g cm−3 and its calculated energetic performance exceeded that of TNT. Except for the perchlorate, these salts are mechanically insensitive. This work explored the methyl sydnone imine cation as a suitable energetic compound, which was quickly obtained through facile syntheses. This is the first exploration of sydnone imines as components of energetic materials.

The aggregation of small molecules in aqueous solution is known to be influenced by the ionic strength of the medium; however, the role played by the identity of salt in the phenomenon of small molecule aggregation is rarely investigated. In the present contribution, we have investigated the effect of counter-anions on the aggregation of a popular cationic amyloid sensing probe, Thioflavin-T (ThT), by taking six different anions, viz. chloride, bromide, acetate, iodide, tetrafluoroborate, and perchlorate. Our results clearly indicate that it is not the ionic strength of the medium which solely controls aggregation of small molecules but distinct ions behave distinctly with regard to the organization. In fact, distinct ion effects play a major role in the salt induced organization of fluorophores. Using detailed steady-state emission, time-resolved emission, and ground-state absorption measurements, the optical properties of salt induced aggregates of ThT have been characterized. We have rationalized our observations on the basis of the theory of matching water affinity, which suggests that the matching free hydration energy is a critical aspect for the formation of contact ion pairs, which eventually results in aggregation. In brief, a larger sized anion, perchlorate, has a lower free energy of hydration and forms a suitable contact ion pair, with a larger organic cation, ThT, having weaker hydration. This contact ion-pair formation subsequently leads to the formation of an aggregate assembly which is found to be emissive in nature. Therefore, it is possible to induce aggregation of ThT by selecting the right counterion with the appropriate size, which may help us to evaluate the false positive signals when high ionic strength and specific counterions are present in the sensing matrix.

Highly emissive tetraphenylethylene chromophore appended thiophenylbipyridine pendant as a receptor (1) site has been successfully synthesized via a multistep reaction pathway. The synthesized chromophore 1 was well characterized by modern spectroscopy. In particular, the solid sample of 1 exhibits significant mechanochromic behavior upon grinding, fuming and heating. The yellow emissive chromophore 1 exhibits remarkable selectivity and sensitivity towards copper(II) perchlorate ions via a photoinduced electron transfer (PET) ‘turn off–turn on’ mechanism. When compared with competing metal ions, 1 shows little to no interference in selectivity towards Cu2+ ions in acetonitrile. Detailed colorimetric, UV-visible, emission, and 1H NMR spectral studies have been employed to understand the sensing mechanism of 1 towards Cu2+ ion interaction which is responsible for PET ‘turn-on’. The binding constant of 1 with Cu2+ was shown to be 2.34 × 10−5 M with a limit of detection as low as 7.93 nM. The binding constant prompted us to explore chromophore 1 as a paper strip sensor for Cu2+ to develop kits for real-world practical utility.

Synthesis, characterization (HRMS, NMR, EPR, UV-Vis spectroscopy, and electrochemistry) and in vitro cytotoxic investigation of a series of new ferrocene-containing derivatives, based on ω-ferrocene carboxylic acids and 2-alkylthioimidazolin-4-ones as well as their copper coordination compounds, have been reported. A series of ferrocene–imidazolone conjugates with different lengths and donor properties of the linker fragments have been synthesized; all the obtained compounds were studied in complexation reactions with copper(I) and copper(II) perchlorates. It is shown that the synthesised conjugates rapidly and efficiently convert coordinating copper ions into the Cu(+1) oxidation state, but a change in the length of the linker in ferrocene–imidazolone ligands fundamentally changes the ratio of products formed as a result of iron oxidation/copper reduction and complexation by various mechanisms. After comparing the data on the qualitative and quantitative composition of the reaction mixtures and the kinetic characteristics of the processes occurring in the mixtures of ferrocene–imidazolones with copper(II) perchlorate, a scheme of the ongoing reactions was proposed which may fully explain all the observed processes and products. It has been shown that the obtained bimetallic Cu/Fe coordination compounds are more toxic than cisplatin and induce apoptosis in micromolar concentrations on Hek-293 and MCF-7 cell lines.

A new cadmium metal–organic framework [Cd(IsoNDI)(ClO4)·H2O]n (ZH-102, IsoNDI = N,N′-di(4-pyridylacylamino)-1,4,5,8-naphthalene diimide) has been synthesized under solvothermal conditions and characterized systematically by elemental analyses, IR spectroscopy, powder X-ray diffraction, and thermogravimetric analyses. Single-crystal X-ray diffraction analysis reveals that ZH-102 exhibits a 2D structure similar to a ‘safety fence’ that further stacks into a 3D supramolecular network, which is constructed by bridging of Cd–IsoNDI with perchlorate (ClO4−) anions and intermolecular interaction. Owing to the presence of electron-deficient NDI moieties and the generation of IsoNDI radicals, ZH-102 displays reversible photochromic properties under irradiation and heating (120 °C) and photocontrolled luminescence properties. In particular, ZH-102 also exhibited vapochromic behavior for detecting amines. Moreover, the ZH-102 showed that excellent heat causes hydrochromism properties with a color change from deep yellow to coffee color when heated at 200 °C. Therefore, ZH-102 possesses multiple chromic properties and could be used as a colorimetric sensor, which provides a new route to design functional MOFs.

An investigation of the impact of the shape, size and coordination ability of counterions was carried out on five silver(I) 1,2-bis(1-methylthioimidazolyl)ethane coordination polymers, namely, [Ag2L(NO3)2]n (1), [Ag2L(SO3CF3)2]n (2), {[AgL][ClO4]}n (3), {[AgL]2[BF4]2}n (4) and {[AgL]3[PF6]3}n (5). They have been characterized by elemental analysis, IR spectroscopy, PXRD and single-crystal X-ray diffraction. [Ag2L(NO3)2]n (1) was produced in the presence of a strongly coordinating anion (NO3−). In the 1D structure of 1, the ligand appears in a pentadentate form and the nitrate acts as a co-ligand in a bidentate coordination fashion. As in 1, in 2 CF3SO3− with a moderately coordinating potential builds up a natural structure with only one kind of coordination mode for the ligand and two types of coordination geometry for the silver atoms. The difference between structures 1 and 2 can be attributed to the size and coordination ability of their anions, which changed the coordination environment of silver ions without changing the coordination fashion of the ligand. In polymer 3, by decreasing the coordination ability and increasing the size of perchlorate relative to that of the previously considered anions, the coordination mode of the ligand and hence the coordination environment of the silver centers were changed. Unlike all the title compounds in the cationic structure of 3, one of the crystallographically independent AgI centers adopts a distorted trigonal planar environment. Complex 4 with an extended helical chain of [Ag2L]n2+ was obtained when AgBF4 with a small, non-coordinated anion was used to react with the L ligand. X-ray diffraction analysis reveals that the most changes were detected in polymer 5 with a rare triple chain structure and a scarce coordination mode of the ligand by using the bulky, uncoordinated PF6− anion. In fact, changing the type of the anion causes a change in the coordination mode of the ligand and in turn in the structural coordination geometry of the polymer. Additionally, the adsorption potential of the polymers was examined by using NH3 and H2S gases.

The first-row transition metal compounds, [MII(L1)2](ClO4)2 (M = Ni (1); Co (2)), have been prepared by treatment of a neutral tetradentate ligand (L1 = N2,N9-dibutyl-1,10-phenanthroline-2,9-dicarboxamide) with metal perchlorate salts in MeOH. Both compounds have been structurally characterized by X-ray crystallography and it was found that the coordination numbers are 6 and 7, respectively. The reaction of 6,6′-bis(2-tbutyl-tetrazol-5-yl)-2,2′-bipyridine (L2) with hydrated FeII(ClO4)2 afforded a 8-coordinate Fe(II) compound, [FeII(L2)2](ClO4)2 (3); however its reaction with hydrated CoII(ClO4)2 resulted in 6-coordinate [CoII(L2)2](ClO4)2. It is interesting to observe field-induced slow magnetic relaxation in the 7-coordinate Co(II) compound 2 and 8-coordinate Fe(II) compound 3, which further supports the validity of designing high coordination number compounds as single-molecule magnets. Direct current magnetic studies demonstrate that 2 has a very large positive D value (56.2 cm−1) and a small E value (0.66 cm−1), indicating easy plane magnetic anisotropy. Consistent with the larger D value, an effective spin-reversal barrier of Ueff = 100 K (71.4 cm−1) is obtained, which is the highest value reported for 7-coordinate Co(II) complexes with a pentagonal bipyramidal geometry. In contrast, 8-coordinate Fe(II) compound 3 exhibits uniaxial magnetic anisotropy.

Two novel supramolecular AIE polymer-based rare earth metallogels (PT-GEu and PT-GTb) were rationally designed and synthesized for the efficient detection and separation of cyanide (CN−) and perchlorate (ClO4−). PT-GEu and PT-GTb were prepared by introducing Eu3+ and Tb3+ into a novel supramolecular polymer (PT-G), which was constructed by the assembly of o-phthalimide functionalized pillar[5]arene host PM and tri-amide guest TH. The supramolecular polymer PT-G shows strong yellow aggregation-induced emission (AIE). Interestingly, after coordination with Eu3+ or Tb3+, the obtained AIE polymer-based rare earth metallogels (PT-GEu or PT-GTb) show “turn-off” AIE. Interestingly, PT-GEu and PT-GTb exhibit selective and sensitive fluorescent “turn-on” recognition for CN− and ClO4−, respectively. The lowest detection limits are 3.36 × 10−6 M for ClO4− by PT-GEu and 5.96 × 10−8 M for CN− by PT-GTb. In addition, the xerogel of PT-GEu and PT-GTb shows nice separation properties for ClO4− and CN−, the adsorption rate of these rare earth metallogels for ClO4− and CN− reached up to 92.86% and 93.33%. Moreover, ion detection test kits were prepared based on these rare earth metallogels, which rapidly detect CN− and ClO4−.

Protonation of pyridines with a strong acid is a general and straightforward approach to achieve efficient aggregation induced emission (AIE) in structurally remarkably simple organic molecules that lack any of the conventional luminophores. The relationship between the nature of counter ion and the AIE efficiency is demonstrated. The superiority of the perchlorate counter ion is attributed to efficient stabilization of the key intermolecular π+–π interactions between neighboring luminophore molecules in the crystal lattice.

Ferroelectrics are polar materials with large spontaneous polarization. Particulate matter, PM2.5, may be polarized and adsorbed by ferroelectrics due to spontaneous polarization. Micron-sized rods of molecular ferroelectric material diisopropylammonium perchlorate (DIPAP) were synthesized by a freeze-drying method to adsorb PM2.5. After low temperature freeze-drying and subsequent high temperature heating, a stable heterojunction DIPAP structure formed with a ferroelectric phase and non-switching phase. The special ferroelectric heterostructure in the DIPAP micron rods gave it excellent photo-induced PM2.5 adsorption. The photoelectric effect has an important role in the photo-induced adsorption. This work shows that molecular ferroelectric heterostructure materials have the potential to be used in creating dust-free spaces and simple outdoor particulate matter removal strategies.

A new pair of multifunctional Zn(II)–Yb(III) complex enantiomers based on a chiral amine-phenol ligand, [YbZn2(SS/RR-L)2(H2O)4](ClO4)3·5H2O (S-1 and R-1) [H2L = (SS/RR)-cyclohexane-1,2-diylbis(azanediyl)-bis(methylene)-bis(2-methoxyphenol)], were synthesized and structurally characterized. In S-1 and R-1, the linear Zn(II)–Yb(III)–Zn(II) metal core is bridged by the phenolate oxygen atoms. Enantiomers S-1 and R-1 show chiroptical activity. Complex S-1 exhibits second-harmonic generation (SHG) and YbIII characteristic emissions in the near-infrared (NIR) region. Magnetic studies indicate that S-1 shows single-molecule magnet (SMM) behaviour. Moreover, S-1 displays a high proton conductivity of 1.55 × 10−4 S cm−1 at room temperature under 100% relative humidity (RH), which results from a 1D H-bonded chain constructed by NH groups of the chiral amine-phenol ligand, water molecules and perchlorate anions (ClO4−). The combination of these five-functions, including chiral, nonlinear optical, magnetic, luminescent and proton-conductive properties, in molecule-based materials may provide great potential for application in smart multifunctional devices.

To obtain a mechanistic understanding of the effects derived from fluorophores, solvents and anions on heavy metal sensing, two NOS2-macrocycle-based fluorosensors with different fluorophores (L1: 9-methylanthracene, L2: benzothiazolyl) were synthesised. In this regard, particular attention was given to monitoring the cation–ligand, cation–anion and cation–solvent interactions from the detailed complexation processes in both the solution and solid states while considering the structure-function relationship. L1 showed turn-on type silver(I) selectivity over other metal ions, including mercury(II), in ethanol. According to the complexation results obtained by titration (UV-vis, fluorescence and NMR), cold-spray ionization mass spectrometry and X-ray crystallography, the observed silver(I) sensing by L1 is mainly due to its 1 : 1 complexation with silver(I) via the Ag–Ntert bond and the strong solvation of mercury(II). Thus, the turn-on sensing for silver(I) can be explained by the CHEF effect, in which the coordination of silver(I) to the receptor unit effectively prevents PET quenching. As a dual-probe (UV-vis and fluorescence) chemosensor, L2 showed fluorescence turn-off type selectivity for both silver(I) and mercury(II) in ethanol. In acetonitrile, L2 showed improved fluorescence turn-off type selectivity for mercury(II) with ClO4− and NO3−; however, no such responses were observed with other anions, such as Cl−, Br−, I−, SCN−, OAc− and SO42−. Together with the complexation results by titration, the crystal structures of an endocyclic mercury(II) perchlorate complex and an exocyclic mercury(II) iodide complex revealed that the anion-controlled mercury(II) sensing by L2 arises from the endo- and exo-coordination modes depending on the anion coordinating ability, which induces either metal–receptor/fluorophore binding (Hg–Ntert and Hg–Nfl) or no binding. Taken collectively, the photophysical, thermodynamic and structural results of the complexations herein suggest that the sensing properties of heavy metal ions by macrocycle-based fluorosensors are very sensitive not only to the cation–receptor and cation–fluorophore interactions but also to the cation–anion (endo/exo-coordination modes) and/or cation–solvent interactions.

Gold nanospheres, coated with luminescent molecules (1-pyrenemethylamine hydrochloride, fluorescein isothiocyanate or cresyl violet perchlorate), have been synthesized and purified by a fast one-step procedure. Luminescent nanoparticles have been obtained, in which the match of the plasmonic and emissive properties gives nanosized fluorophores useful in different application fields.

The perchlorate series of nitrosyl ruthenium tetrapyridine-cations trans-[RuNOPy4X]n+ (where X = OH, Cl, and H2O) were synthesized. The exchange of the anion in an excess of sodium perchlorate results in the formation of the hydroxo complex, with perchlorate as a counter-anion. The protonation of the coordinated hydroxyl resulted in the formation of the aqua complex in acidic media. The outcome of the protonation depends on the choice of the acid. The use of non-coordinating perchloric acid leads to the aqua complex as the product. The ruthenium nitrosyl complex with a coordinated chloride anion was a result of the interaction of the hydroxo complex with concentrated hydrochloric acid. The crystal structures were determined using X-ray single crystal analysis. The 445 nm irradiation promotes electron transfer from the metal orbital to the antibonding orbital of the nitrosyl group. In the solid phase, this metal-to-ligand charge transfer results in the formation of the metastable states with Ru–ON coordination. These photoinduced linkage isomers for each complex were monitored by IR-spectra and their stability was measured using the temperature sweep method described in an earlier study.

Hydrophobic ionic liquids containing bis(trifluoromethanesulfonyl)imide, [NTf2]-, anions partially dissolve in aqueous phases. The potential ecotoxicity of [NTf2]- means wastewater streams must be closely monitored to avoid environmental release. A new ion chromatography method is presented, which improves on existing techniques and methods by significantly decreasing analysis time and improving chromatographic peak properties. Consequently, the limit of detection is lowered to 5 μM (1.4 ppm) and limit of quantification lowered to 30 μM (8.5 ppm). The method is reproducible and has a high precision for short and medium chain length ionic liquids (RSD = 0.95%); however, microemulsion effects increase measurement errors for long chain ionic liquids (RSD = 2.32%), albeit by a relatively small amount. Hence, the method is a highly accurate analytical method for highly polarizable [NTf2]- anions, and quantification in the presence of high salinity samples, such as seawater, is readily achieved. Importantly, this method is a significant improvement on existing techniques (chromatography, NMR, UV-Vis) for many reasons, making it ideal for environmental monitoring or process design of [NTf2]- ionic liquid-based applications.

Treating toxic monovalent anions such as NO3− or ClO4− in drinking water remains challenging due to the high capital and environmental costs associated with common technologies such as reverse osmosis or ion exchange. Capacitive deionization (CDI) is a promising technology for selective ion removal due to high reported ion selectivity for these two contaminants. However, the impacts of ion selectivity and influent water characteristics on CDI life cycle cost have not been considered. In this study we investigate the impact of ion selectivity on CDI system cost with a parameterized process model and technoeconomic analysis framework. Simulations indicate millimolar concentration contaminants such as nitrate can be removed at costs in the range of $0.01–0.30 per m3 at reported selectivity coefficient ranges (S = 6–10). Since perchlorate removal involves micromolar scale concentration changes, higher selectivity values than reported in literature (S > 10 vs. S = 4–6.5) are required for comparable treatment costs. To contextualize simulated results for CDI treatment of NO3−, CDI unit operations were sized and costed for three case studies based on existing treatment facilities in Israel, Spain, and the United States, showing that achieving a nitrate selectivity of 10 could reduce life cycle treatment costs below $0.2 per m3.

A rapid and sensitive method is described for measuring perchlorate (ClO4−), chlorate (ClO3−), chlorite (ClO2−), bromate (BrO3−), and iodate (IO3−) ions in natural and treated waters using non-suppressed ion chromatography with electrospray ionization and tandem mass spectrometry (NS-IC-MS/MS). Major benefits of the NS-IC-MS/MS method include a short analysis time (12 minutes), low limits of quantification for BrO3− (0.10 μg L−1), ClO4− (0.06 μg L−1), ClO3− (0.80 μg L−1), and ClO2− (0.40 μg L−1), and compatibility with conventional LC-MS/MS instrumentation. Chromatographic separations were generally performed under isocratic conditions with a Thermo Scientific Dionex AS16 column, using a mobile phase of 20% 1 M aqueous methylamine and 80% acetonitrile. The isocratic method can also be optimized for IO3− analysis by including a gradient from the isocratic mobile phase to 100% 1 M aqueous methylamine. Four common anions (Cl−, Br−, SO42−, and HCO3−/CO32−), a natural organic matter isolate (Suwannee River NOM), and several real water samples were tested to examine influences of natural water constituents on oxyhalide detection. Only ClO2− quantification was significantly affected – by elevated chloride concentrations (>2 mM) and NOM. The method was successfully applied to quantify oxyhalides in natural waters, chlorinated tap water, and waters subjected to advanced oxidation by sunlight-driven photolysis of free available chlorine (sunlight/FAC). Sunlight/FAC treatment of NOM-free waters containing 200 μg L−1 Br− resulted in formation of up to 263 ± 35 μg L−1 and 764 ± 54 μg L−1 ClO3−, and up to 20.1 ± 1.0 μg L−1 and 33.8 ± 1.0 μg L−1 BrO3− (at pH 6 and 8, respectively). NOM strongly inhibited ClO3− and BrO3− formation, likely by scavenging reactive oxygen or halogen species. As prior work shows that the greatest benefits in applying the sunlight/FAC process for purposes of improving disinfection of chlorine-resistant microorganisms are realized in waters with lower DOC levels and higher pH, it may therefore be desirable to limit potential applications to waters containing moderate DOC concentrations (e.g., ∼1–2 mgC L−1), low Br− concentrations (e.g.

A simple semi-empirical approach is proposed to calculate structure and properties of crystals under pressure at fixed temperatures.

The extraction and complexation of trivalent Am(III) and lanthanide(III) with a new phenanthroline-derived phosphonate ligand, tetrabutyl-(1,10-phenanthrolin-2,9-diyl)phosphonate (C4-POPhen), were investigated by solvent extraction, absorption spectroscopy, NMR titration, luminescence spectroscopy, and theoretical computation. Selective extraction of Am(III) over Eu(III) from highly acidic HNO3 solution (up to 3.0 M) with good selectivity and a fast extraction rate was achieved by using the C4-POPhen ligand. The 1 : 2 metal/ligand complex was found to be the predominant species in the extracted organic phase by a slope analysis method. NMR titration results demonstrated that only a 1 : 1 complex of C4-POPhen with Ln(NO3)3 was formed in a CH3OH system, while two complexes (1 : 1 and 1 : 2) were found when using Ln(ClO4)3 as the metal salts instead of Ln(NO3)3. The stability constants of the C4-POPhen/Am(III) and C4-POPhen/Ln(III) complexes in CH3OH with perchlorate and nitrate were determined by absorption spectroscopy. The Am(III) complexes exhibited higher complexation ability than Ln(III), which was consistent with the extraction results. DFT calculations also suggested that the Am–N bonds in C4-POPhen/Am(III) complexes had a higher degree of covalence than the Eu–N bonds in C4-POPhen/Eu(III) complexes, revealing the underlying driving force for the extraction selectivity of Am(III) over Eu(III) by C4-POPhen. These results indicate that phenanthroline-derived phosphate ligands may serve as promising candidates for separation of trivalent actinides over lanthanides from highly active nuclear waste.

The syntheses of oxidorhenium(V) complexes [ReOCl(L1a–c)2] (3a–c), equipped with the bidentate, mono-anionic phenol–dimethyloxazoline ligands HL1a–c are described. Ligands HL1b–c contain functional groups on the phenol ring, compared to parent ligand 2-(4,4-dimethyl-4,5-dihydro-1,3-oxazol-2-yl)-phenol H1a; namely a methoxy group ortho to the hydroxyl position (2-(4,4-dimethyl-4,5-dihydro-1,3-oxazol-2-yl)-6-methoxyphenol, H1b), or a nitro group para to the hydroxyl position (2-(4,4-dimethyl-4,5-dihydro-1,3-oxazol-2-yl)-4-nitrophenol, H1c). Furthermore, oxidorhenate(V) complexes (NBu4)[ReOCl3(L1a–b)] (2a–b) were synthesized for solid state structural comparisons to 3a–b. All novel complexes are fully characterized including NMR, IR and UV-Vis spectroscopy, MS spectrometry, X-ray crystallography, elemental analysis as well as cyclic voltammetry. The influence of functional groups (R = –H, –OMe and –NO2) on the catalytic activity of 3a–c was investigated in two benchmark catalytic reactions, namely cyclooctene epoxidation and perchlorate reduction. In addition, the previously described oxidorhenium(V) complex [ReOCl(oz)2] (4), employing the phenol–oxazoline ligand 2-(4,5-dihydro-2-oxazolyl)phenol Hoz, was included in these catalysis studies. Complex 4 is a rare case in oxidorhenium(V) chemistry where two stereoisomers could be separated and fully characterized. With respect to the position of the oxazoline nitrogen atoms on the rhenium atom, these two stereoisomers are referred to as N,N-cis and N,N-trans isomer. A potential correlation between spectroscopic and structural data to catalytic activity was evaluated.

The asymmetric 3,5-disubstituted 1,2,4-triazole ligand H2V (5-amino-3-picolinamido-1,2,4-triazole) by reaction with an excess of Cu(II) perchlorate (Cu : H2V being 12 : 1) has produced a novel hexanuclear {Cu6(m3-O/H)(HV/V)3} fragment, with one triangular Cu3(m3-O/H) group connected to three peripheral single Cu(II) ions through a cis–cis–trans bridging mode of the ligand, which is the building block of the three structures described here: one hexanuclear, [Cu6(m3-O)(HV)3(ClO4)7(H2O)9]$8H2O (1), one dodecanuclear, [Cu12(m3-O)2(V)6(ClO4)5(H2O)18](ClO4)3$6H2O (2), and one tetradecanuclear 1D-polymer, {[Cu14(m3-OH)2(V)6(HV)(ClO4)11(H2O)20](ClO4)2$14H2O}n (3), the last two containing hexanuclear subunits linked by perchlorato bridges. The Cu–Cu av. intra-triangle distance is 3.352(2) A and the Cu(central) ˚ – Cu(bridged external) av. distance is 5.338(3) A. The magnetic properties of the hexanuclear ˚ “Cu3O–3Cu” cluster have been studied, resulting as best fit parameters: g ¼ 2.18(1), J(intra-triangle) ¼ 247.0(1) cm1 and j(central CuII – external CuII) ¼ 5.15(2) cm1 . This work was supported by the Spanish Ministerio de Econom´ıa y Competitividad and FEDER (CTQ2016-78341-P), Unidadde Excelencia Mar´ıa de Maeztu (MDM-2015-0538) and Generalitat Valenciana through PROMETEO/2016/147. F. J. V.-M. thanks MINECO for a predoctoral (FPI) grant SI

It is a formidable challenge to achieve highly efficient organic afterglow and readily tunable transient and persistent phosphorescence of organic materials because of the lack of valid design principles. Herein, we report the regulation of the transient and persistent room-temperature phosphorescence of organic ionic crystals by the alteration of anions, and the unique size-dependent ultralong afterglow of tetraphenylphosphonium perchlorate (TPP ClO4) crystals under ambient conditions. Three organic ionic crystals show sharply distinct triplet emissions based on three heavy-atom free anions by proper construction of donor–acceptor patterns in the crystals. TPP ClO4 crystals exhibit ultrabright transient phosphorescence and ultralong afterglow, and the gradual enhancement of the afterglow with the crystal size directly proves the generation of ultralong afterglow from aggregates with strong intermolecular interactions in the crystals. These results greatly contribute to the general design principles of highly efficient transient and persistent phosphorescence and their regulations by rational design. Highly sensitive detection and imaging of perchlorate ions are achieved in a phosphorescence turn-on manner based on the bright room-temperature phosphorescence of TPP ClO4 crystals, and valuable anti-counterfeiting applications of the ultralong afterglow of TPP ClO4 crystals are also demonstrated in practical examples.

Six azonia cyanine dyes (1a–f) based on the [1,2-a]pyrimidin-5-ium perchlorate unit were prepared to study their optical properties after interaction with nucleic acids and their potential applications in cell imaging. Dyes 1a–c consist of pyrimidin-5-ium perchlorates (4a–c) and a coumarin unit (5a) linked by conjugated double bonds, while 1d–f were endowed with different conjugated structures through the condensation between pyrimidin-5-ium perchlorates and 6-(diethylamino)-2,3-dihydro-1H-xanthene-4-carbaldehyde (5b). Due to these different structures, they demonstrate different properties. The optical properties of the dyes in five different solvents were measured; dyes 1a–c exhibited strong fluorescence in low polarity solvents (Φ up to 44.9% in dichloromethane) but much weaker fluorescence in high polarity solvents (Φ low to 1.5% in methanol), while dyes 1d–f showed no regular fluorescence properties in these solvents. Then, the optical responses of dyes 1a–f toward nucleic acid indicated that 1a–c are turn-on type near infrared (NIR) nucleic acid probes (maximum emission wavelength range: 678 nm to 698 nm) with large Stokes shifts (143 nm to 155 nm). Among these, the relative fluorescence quantum yield of 1a increased 25.2 times (from 0.4% to 10.1%) and the maximum fluorescence intensity was enhanced by 14.4 fold after interacting with RNA. Additionally, cell imaging experiments indicated that dyes 1a–c can be used to image the nucleolus in fixed HeLa cells.

Anion exchange of the symmetrical benzo[cd]indolenyl-substituted heptamethine cyanine dyes from a small hydrophilic perchlorate (ClO4−) anion to a large hydrophobic tetrakis(pentafluorophenyl)borate ((C6F5)4B−) anion resulted in the reduction of the hydrophilic molecular interaction. Consequently, the prepared benzo[cd]indolenyl-substituted heptamethine cyanine dyes carrying the (C6F5)4B− anion can be purified by column chromatography, even with the use of a less polar solvent, such as dichloromethane, because the Rf values of the symmetrical benzo[cd]indolenyl-substituted heptamethine cyanine dyes carrying the (C6F5)4B− anion are much greater than that of the dye carrying the ClO4− anion. Significantly, the symmetrical benzo[cd]indolenyl-substituted heptamethine cyanine dye 5 carrying a cyclopentene ring shows no absorption in the visible light region in CH2Cl2. Among them, the prepared benzo[cd]indolenyl-substituted heptamethine cyanine dye 5c carrying the (C6F5)4B− anion and 4-methylphenoxy group at the meso-position is most thermostable. Furthermore, the prepared benzo[cd]indolenyl-substituted heptamethine cyanine dye 5c carrying the (C6F5)4B− anion and 4-methylphenoxy group at the meso-position is also photostable, as is the dye carrying the ClO4− anion in dichloromethane under irradiation by a white LED at 25 °C, with the exception of the dye carrying a 4-tolylthio substituent at the meso-position.

Herein, two metal organic frameworks (MOFs), namely, [{Cu2(μ-OH)(μ-OAc)(H2O)(OAc)(bpy)2}NO3·4H2O]n (CuMOF-1) and [{Co(bpy)(ClO4)2(H2O)2}·bpy]n (CoMOF-2), where bpy = 4,4′-bipyridine, were synthesized, characterized and explored for their material importance in magnetism and dye adsorption. Under solvothermal conditions, two different metal salts (nitrate and perchlorate) were reacted with a simple bench chemical, i.e., a dipyridine derivative, namely, bpy to afford two MOFs having different yet interesting topologies and adsorption properties. The structure of CuMOF-1 was built from the repeating building blocks of the dinuclear cationic Cu(II) units composed of two Cu(II) ions, two bpy ligands, two acetate ions (OAc), one hydroxide ion (OH−) and a water molecule. Interestingly, two different Cu atoms existed in the structure with two different coordination geometries, i.e., octahedral and trigonal bipyramidal. The sql topology of the resulting 4-c uninodal net with point symbol {44·62} was obtained for CuMOF-1. The cluster representation of CuMOF-1 further gave hxl topology with 6-c uninodal nets (point symbol: {36·46·53}). CoMOF-2 was built from repeating mononuclear Co(II) units, where each Co atom coordinated with two bpy ligands, two perchlorate ions and two water molecules, resulting in octahedral geometry around the Co(II) ions. The surprising nature of the structure of CoMOF-2 was that one bpy ligand was coordinated with cobalt, while the second bpy ligand was present in the lattice in between layers, thus consolidating the structure by strong hydrogen bonding with the coordinated water molecules of the neighboring units. The resulting underlying net in CoMOF-2 was 2C1 with sql topology. The magnetic data indicated the presence of strong antiferromagnetic interactions in MOFs (J = −98.21 cm−1 in CuMOF-1 and θ = −8.8 K in CoMOF-2). The present MOFs were exploited for the adsorption of two dyes, namely, methylene blue (MB) and methyl orange (MO), which are organic pollutants. The adsorption studies confirmed that CoMOF-2 is a more selective adsorbent for MB. The kinetic data disclosed the pseudo-second-order mechanism of adsorption in both cases. The cation/anion–π interaction between the dyes and π-electron-rich bpy was responsible for the adsorption behaviour of MOFs. Moreover, the presence of free bpy in the lattice of CoMOF-2 gave rise to the strongest interactions, making CoMOF-2 the best adsorbent.

A series of coordination complexes, [Ag2(PPh2Py)2(MeCN)4](ClO4)2·MeCN (1), [Ag2(PPh2Py)2(ClO4)2]n·2(CH2Cl2)n (2), [Cu2(PPh2Py)2(MeCN)2](ClO4)2 (3) and [Cu2(PPh2Py)2(ClO4)2]n (4), were synthesized and characterized by single crystal X-ray crystallography. In the crystal structures, 2 and 4 form one-dimensional coordination polymers with perchlorate ions in the presence of bridging ligands. They exhibit strong luminescence in the crystalline state but are dramatically quenched when exposed to alcohol or nitrile vapors. 1 and 3 are non-emissive 0-dimensional complexes with coordinating acetonitrile solvent molecules. The structures of 1 and 3 reveal that alcohol or nitrile vapors could replace the bridging perchlorate ions in 2 and 4 so as to occupy the metal coordination sites. This structural transformation from 1D to 0D makes 2 and 4 promising candidate materials for the detection of alcohols and nitriles.

Mo-Dependent perchlorate reductase (PcrAB), responsible for the ending step of anaerobic respiration of perchlorate reducing bacteria, catalyzes the conversion of perchlorate to chlorate and subsequently chlorite and is also able to deoxidate bromate, iodate, and nitrate. Herein, the reaction mechanisms for the PcrAB-catalyzed decomposition of these oxyanions have been investigated using density functional calculations and a chemical model constructed from the X-ray crystal structure. It is revealed that the reactions of halogen oxyanions proceed through a very fast O-X (X = Cl, Br, and I) heterolytic cleavage activated by the MoIV center, followed by a rate-limiting reduction of the resulting MoVI[double bond, length as m-dash]O back to MoIV dominated by the slow proton-coupled electron transfer (PCET). However, the O-N bond heterolysis in the nitrate decomposition has a barrier (16.2 kcal mol-1) comparable to the PCET-dominating reduction of MoVI[double bond, length as m-dash]O. This heralds an exciting future where a proper mutation of electron/proton transfer passage of perchlorate reducing bacteria may lead to a decomposition preference for halogen oxyanions rather than non-toxic nitrate, providing a friendly bioremediation method. Other open mechanistic questions are also addressed, where in particular an O-O rebound mechanism without PCET has been ruled out.

Here we present two isostructural iron(iii) spin crossover complexes with the same tridentate ligand and perchlorate or tetrafluoroborate as counter ion. Single crystal X-ray structures in the high spin and low spin state were obtained for both complexes. An abrupt spin transition above 100 K is observed with the transition temperature depending on the size of the anion.

Molecular ferroelectrics are a kind of functional materials that have large application prospects. Comparing with the traditional inorganic ferroelectrics, they have some advantages, such as easy design, environment-friendliness, nontoxicity, and flexibility. In this study, a new molecular ferroelectric pyridin-2-ylmethanaminium perchlorate was discovered, which undergoes a ferroelectric phase transition at around 264.8 K. The spontaneous polarization reaches 0.22 μC cm−2, and the coercive fields are as small as 1.1 kV cm−1 at 202 K. The single-crystal X-ray diffraction analysis reveals that the space group transforms from a polar space group of P21 at 173 K to a centrosymmetric space group of P21/c at 293 K. By analyzing the crystal structure changes below and above the phase transition temperature, it can be concluded that the phase transition is induced by the disorder of perchlorate. Its ferroelectricity was confirmed by the measurements of differential scanning calorimetry, dielectric and hysteresis loop.

Interactions of anionic guests with a tritopic peripherally functionalized conjugated calix[4]pyrrole host (1) prepared using a regioselective synthetic method is reported. The regioselectivity of synthesis relies on selective N-alkylation of the calix[4]pyrrole caused by peripheral substitution of one pyrrole group with subsequent N-alkylation at the opposing pyrrole group termed by us ‘knock-on’ regioselectivity. The resulting host molecule exhibits anion interactions with common chloride and nitrate anions enhanced by an order of magnitude over the parent conjugated calix[4]pyrrole. Combined analysis of 1H NMR and UV-vis spectroscopic titration data enabled an evaluation of binding strengths of anions with the host KA in a binding model where the salt dissociation process is also incorporated in the form of its dissociation constant Kd. Anions could be classified as two types based on their interactions with 1: Type A anions (chloride, nitrate, perchlorate, hydrogensulphate) associate as 1 : 1 complexes through hydrogen bonding while interactions involving Type B anions (acetate, fluoride, dihydrogenphosphate) are complicated by host deprotonation and/or countercation association. Hosts based on rim-functionalized calix[4]pyrroles such as 1 represent a promising new family of chromophores for estimation of biologically relevant anions or other species.

A new symmetrical and flexible primary amide functionalized ligand, 2,2′-(ethane-1,2-diylbis((pyridin-2-ylmethyl)azanediyl))diacetamide (2-BPEG), has been synthesized and structurally characterized. Using this multidentate ligand, four novel metal complexes, namely [Cu(2-BPEG)](ClO4)2·0.5H2O (1), [Zn(2-BPEG)](ClO4)2 (2), [Zn(2-BPEG)](ZnCl4)·H2O (3) and [Cd(2-BPEG)(H2O)](ClO4)2·H2O (4), have been synthesized under ambient conditions and characterized by elemental, spectroscopic and thermal analysis, and single and powder X-ray diffraction. Complexes 1–3 are hexacoordinated with an N4O2 donor set (provided by the hexadentate 2-BPEG ligand), while complex 4 is heptacoordinated with an additional coordinated water molecule. In all cases, the 2-BPEG ligand acts as a hexadentate ligand. A change in the starting metal salt has resulted in the formation of 2 and 3 with different tetrahedral anions, ClO4− and ZnCl4−, respectively. This has provided an opportunity to showcase anion-directed supramolecular networks for these compounds. Compounds 1, 2 and 4 with perchlorate anions show similar and comparable intermolecular interactions in their 3D networks. On the other hand, the supramolecular self-assembly of 3 is dominated by a variety of intermolecular interactions such as C–H⋯Cl, N–H⋯Cl, O–H⋯Cl and C–H⋯O due to the presence of a tetrachlorozincate(II) ion. Moreover, the role of weak intermolecular interactions in the crystal packing has been analysed and quantified using Hirshfeld surface analysis. Furthermore, compound 4 exhibiting an open Lewis acid site has been found to be a very efficient and recyclable heterogeneous catalyst for the solvent-free cyanosilylation of various aldehydes with trimethylsilyl cyanide (TMSCN) producing the corresponding trimethylsilyl ether in high yields.

International audience; Five new cyanido-bridged heterometallic coordination polymers have been obtained by reacting PPh4[RuIII(salpn)(CN)2]·H2O (1) and AsPh4[RuIII(valen)(CN)2]·8.5H2O (2) (H2salpn and H2valen being Schiffbase proligands resulting from the condensation reaction of salicylaldehyde with 1,3-propanediamine and, respectively, o-vanillin with 1,2-ethanediamine) with divalent transition metal perchlorate salts: 1 1 [{RuIII(salpn)(CN)2}3{MII(DMF)3}2](ClO4)·4DMF (MII = Mn, 3; Co, 4) and 12 [{RuIII(valen)(CN)2}4{MII(DMF)3}2 {MII(DMF)4}](ClO4)2·4DMF (MII = Mn, 5; Co, 6; Ni, 7), respectively. The dicyanido species, trans-[Ru(salpn) (CN)2]− and trans-[Ru(valen)(CN)2]−, act as metalloligands with the 3d metal ions. Compounds 3 and 4 are isostructural one-dimensional (1D) coordination polymers with a ladder topology. Each MII ion is hexacoordinatedby three cyanido groups arising from three {Ru(salpn)(CN)2} units and by the oxygen atoms from three DMF molecules, which are coordinated at meridional positions. Compounds 5–7 are also isostructural, their structures consisting of 2D networks with a herringbone topology. The magnetic susceptibility measurements of these 1D and 2D systems reveal the presence of dominating RuIII–MII antiferromagnetic (AF) interactions in compounds 3, 4, 5 and 6, while ferromagnetic RuIII–NiII interactions are observed in 7. All these compounds stay in their paramagnetic state down to 1.8 K except compound 4 which possesses a 3D ordered AF ground state.

Anion complexes of the cryptand built with the tripodal amine tris(2-aminoethyl)amine, known as tren, with water and several oxoanions of biological and environmental interest (nitrate, sulfate, phosphate, perchlorate and arsenate) have been crystallized from aqueous solution and resolved with single-crystal X-ray diffraction. All crystals show guest species encapsulated in the interior of the cavity as well as, in some cases, sitting in the grooves defined by the arms of the macrocycle. Hydrogen bonding and electrostatic interactions play a major role in anion binding to the host. The macrocycle is able to encapsulate anions in a wide range of protonation degrees. Solution studies have been carried out to show that those interactions happen also in solution in addition to the solid state. The results show that the receptor binds consistently to the ligand in a wide range protonation degrees., Financial support by the Spanish Ministerio de Economía y Competitividad (projects CTQ2016-78499-C6-1-R, Unidad de Excelencia MDM 2015-0038 and CTQ2017-90852-REDC) and Generalitat Valenciana (Project PROMETEOII2015-002) is gratefully acknowledged. S. B. thanks MINECO for a Juan de la Cierva postdoctoral grant.

A family of di-nuclear bis(benzotriazole iminophenolate) (BiIBTP) cobalt complexes containing diverse ancillary carboxylate derivatives have been synthesized and structurally characterized. The one-pot synthesis of the BiIBTP ligand precursor with cobalt perchlorate salt (2.0 equiv.) and carboxylic acid derivatives (2.0 or 5.0 equiv.) in the presence of triethylamine (5.0 equiv.) under refluxing methanolic solution generated bimetallic di-carboxylate Co(II)/Co(II) complexes [(C83CBiIBTP)Co2(O2CR)2] (R = C6H5 (1), C6F5 (2), 4-CF3–C6H4 (3), 4-OMe–C6H4 (4), CF3 (5)) in ≧65% yields. Interestingly, the Co(II)/Co(III) mixed-valence complex 6 resulted from the treatment of 1 with silver perchlorate (1.0 equiv.) as the oxidizing agent under an O2-atmosphere in 50% yield. The crystal structure of 6 reveals an ionic and di-nuclear benzoate species composed of a cationic moiety formulated as [(C83CBiIBTP)Co2(O2CC6H5)2]+ and a counterbalanced perchlorate anion, and both metal atoms are attributed to hexa-coordinated cobalt ions with varied coordination environments. Catalysis results of CO2/epoxide copolymerization indicated that complex 1 was more efficient than 2–6 where compound 6 was shown to be the least active. Co complex 1 incorporating benzoate coligands was demonstrated to effectively catalyze the CO2-copolymerization of cyclohexene oxide (CHO), 4-vinyl-1,2-cyclohexene oxide or cyclopentene oxide, producing the associated CO2-based polycarbonates with >99% carbonate repeated units under optimal conditions. Not only the controllable character of complex 1 for CO2/CHO copolymerization is enabled, but also 1 has been shown to catalyze such a copolymerization in the “immortal” manner. Using the same di-cobalt catalyst in combination with excess ratios of neopentyl glycol (up to 150 equiv.) as the chain transfer agent could give low molecular weight poly(cyclohexene carbonate) polyols with monomodal molecular weight distributions. This work offers the facilely prepared di-nuclear cobalt complexes as catalysts for the efficient catalysis of CO2-copolymerization.

Herein, the water oxidation activities of two cobalt complexes (cobalt(II) phthalocyanine and N,N′-bis(salicylidene)ethylenediamino cobalt(II)) were studied. The experiments showed that at pH 11, N,N′-bis(salicylidene)ethylenediamino cobalt(II) and cobalt(II) perchlorate were active for water oxidation. On the other hand, for cobalt(II) phthalocyanine as a stable complex, no water oxidation was observed. The role of nanosized particles containing Co, P, and O in the electrochemical oxidation of water by cobalt complexes was investigated by some methods. After the water oxidation reaction, both complexes and the cobalt salt were studied and a relationship between the decomposition of the cobalt complex and water oxidation was proposed. A critical point is that on the surface of the electrode, there are some areas without any detectable nanoparticles, and thus, the detection of such cobalt compounds on the surface of the electrode is not easy even by high-resolution visible spectroelectrochemistry and scanning electron microscopy. Such experiments showed that to propose a molecular mechanism for water oxidation in the presence of metal complexes, careful analysis is necessary to rule out the role of nanoparticles.

Currently used primary explosives suffer not only from various drawbacks like insidious sensitivities toward mechanical stimuli and electrostatic discharge, but also from environmental concerns largely attributed to toxic lead compounds. These issues can directly be related to higher risk during processing and handling of these sensitive materials. In this research, 12 new lead-free energetic coordination compounds (ECCs) based on three isomeric propyl-linked ditetrazoles as ligands with moderate sensitivities are described, which can be initiated reliably and safely by irradiation with near infrared light (NIR). Excellent thermal stabilities for all complexes up to an outstanding decomposition temperature of 297 °C for compound 7 could be achieved through the formation of stable polymeric networks. The optical and energetic properties of these complexes can easily be customized by variation of various building blocks like different transition metals (Mn2+, Fe2+, Ni2+, Co2+, Cu2+, Zn2+, and Ag+) and anions (perchlorate, styphnate, cyanodinitromethanide and dinitramide) and for the first time by the use of three different isomeric ditetrazole ligands. 1,3-Di(tetrazol-1-yl)propane (1,1-dtp), 1-(tetrazol-1-yl)-3-(tetrazol-2-yl)propane (1,2-dtp) and 1,3-di(tetrazol-2-yl)propane (2,2-dtp) were prepared in a convenient and straightforward one-step alkylation reaction of 1,5H-tetrazole. The obtained compounds were extensively characterized by e.g. XRD, IR, EA, UV/Vis and DTA. In addition, the sensitivities toward external stimuli (impact, friction and electrostatic discharge) were determined according to Bundesamt fur Materialforschung und -prufung (BAM) standard methods. Iron(II) 5 and copper(II) perchlorate complexes 8, 11 and 12 show promising characteristics and could be potential candidates for possible applications in the future.

The Mn(III) dinuclear compounds [{Mn(bpy)(H2O)}(μ-2,6-Cl2C6H3COO)2(μ-O){Mn(bpy)(X)}]X, where X = ClO4 (1) or X = NO3 (2), were synthesised and characterised by X-ray diffraction spectroscopy. In both cases there were hydrogen bond interactions between the aqua ligand and counteranions, but with different connectivity patterns. For compound 1, the interactions connected two dinuclear complexes through two perchlorate counteranions to generate a tetranuclear unit. For compound 2, the hydrogen bond was “intramolecular” between the cationic complex, nitrate counteranion and crystallization water (Mn–LW⋯NO3−⋯H2O⋯LN–Mn). This unusual interaction was responsible for the perfect orthogonality of the coordination octahedra on the dinuclear entity and noticeable elongation of these polyedra. Both compounds showed antiferromagnetic coupling, which was unusually strong for compound 2 with a nitrate anion (J = −9.2 and −27.3 cm−1 for 1 and 2, respectively) (H = −J·S1·S2). The effect of the counteranion (X) on the magnetic interaction was analysed by density functional theory studies. For both compounds, hydrogen bonds between the aqua ligand and counteranions weakened the antiferromagnetic interaction. Moreover, for 2, replacement of the counteranion nitrate with other groups had a significant effect on the magnetic interaction.

The nickel-catalyzed enantioselective sequential Nazarov cyclization/decarboxylation has been developed. The use of chiral oxazoline iminopyridine and metal perchlorate allows the enantioselective decarboxylative electrocyclization of divinyl ketones bearing an α-ester group to afford chiral cyclopentenones in good yields with excellent enantioselectivities. Various derivatizations could be easily carried out to deliver chiral polysubstituted cyclopentenes. Primary mechanistic studies demonstrated that nickel-catalyzed asymmetric Nazarov cyclization was followed by nickel-promoted decarboxylation.

Four new 2-amino-5,7-dimethyl-1,8-naphthyridine derivatives (1–4) possessing urea, amide-imidazolium salt, amide-azide, or amide-triazole moieties were synthesized in good to excellent yields by derivatization of 2-amino-5,7-dimethyl-1,8-naphthyridine. We examined their anion recognition abilities towards different anions such as fluoride, chloride, bromide, iodide, nitrate, dihydrogen phosphate, cyanide, hexafluorophosphate, perchlorate, hydrogen sulphate and acetate by 1H NMR and UV-Vis spectroscopy. Among various 2-amino-5,7-dimethyl-1,8-naphthyridine derivatives, only 1a and 2 showed spectroscopic and colorimetric change when treated with fluoride ions among other anions. The F− ions first established a hydrogen-bonding interaction with 1a to give the most stable 1 : 1 complex and then, after addition of a second equivalent, the F− ions induced urea deprotonation due to the formation of HF2−. Moreover, 2 underwent deprotonation of amide –NH proton after the addition of 1 equiv. of fluoride ions. The action of the probes was thoroughly investigated by DFT calculations that also supported the H-bonding induced deprotonation sensing mechanism.

Biocatalytic technologies are characterized by targeted, rapid degradation of contaminants over a range of environmentally relevant conditions representative of groundwater, but have not yet been integrated into drinking water treatment processes. This work investigated the potential for a hybrid ion-exchange/biocatalytic process, where biocatalysis is used to treat ion-exchange waste brine, allowing reuse of the brine. The reduction rates and the fate of the regulated anions perchlorate and nitrate were tested in synthetic brines and a real-world waste brine. Biocatalysts were applied as soluble protein fractions from Azospira oryzae for perchlorate reduction and Paracoccus denitrificans and Haloferax denitrificans for nitrate reduction. In synthetic 12% brine, the biocatalysts retained activity, with rates of 32.3 ± 6.1 U (μg Mo)−1 for perchlorate (A. oryzae) and 16.1 ± 7.1 U (μg Mo)−1 for nitrate (P. denitrificans). In real-world waste brine, activities were slightly lower (20.3 ± 6.5 U (μg Mo)−1 for perchlorate and 14.3 ± 3.8 U (μg Mo)−1 for nitrate). The difference in perchlorate reduction was due to higher concentrations of nitrate, bicarbonate, and sulfate in the waste brine. The predominant end products of nitrate reduction were nitrous oxide or dinitrogen gas, depending on the source of the biocatalysts and the salt concentration. These results demonstrate biocatalytic reduction of regulated anions in a real-world waste brine, which could facilitate brine reuse for the regeneration of ion-exchange technologies and prevent reintroduction of these anions and their intermediates into the environment.

A cadmium(II)-based MOF, Cd-MDIP, was successfully prepared by hydrothermal reaction between the tetra-carboxylic ligand 5,5′-methylenebisophthalic acid (H4MDIP) and cadmium perchlorate. The X-ray crystal structure analysis showed that there are two uncoordinated carboxyl groups in each ligand and a 1D elliptical channel along the [001] direction. Because of the existence of uncoordinated carboxyl groups within open frameworks, Cd-MDIP exhibited a high sensitivity (Stern–Volmer constant KSV = 4.13 × 104 L mol−1) and a low detection limit (80 nM) for Fe3+ ions in pure water, which is much lower than the national standard for Fe3+ in daily drinking water (5.4 μM) set by the Ministry of Environmental Protection of P. R. China. Most importantly, Cd-MDIP also featured the ultrahigh adsorption of Fe3+ in aqueous solution that cannot be destroyed even by EDTA/base. Importantly, the MOF material (Cd-MDIP⊃Fe3+) after adsorbing Fe3+ could act as the first example of an excellent bi-metallic Lewis-acid catalyst for the cyanosilylation reaction of aromatic aldehydes in a size-selective fashion, and its efficiency was almost 10-times higher than that of the original Cd-MDIP.

A series of ethylenediamine-grafted ion imprinted magnetic polymers (Fe3O4@IIPs) were synthesized via ultrasonic assisted suspension polymerization with perchlorate (ClO4−) as an ion imprinting template. They were characterized by XRD, EA, VSM, FTIR and XPS and applied as adsorbents for ClO4− removal from aqueous solutions. The effects of the usage amount of crosslinking agent divinylbenzene (DVB) used for preparation on the structure and the adsorptive performance of Fe3O4@IIPs were investigated. The results show that the Fe3O4@IIPs have an average size of 200–800 nm, which increases with the increase of the amount of DVB from 0 to 2 g during the preparation process. The saturation magnetization intensities are at 35.6–42.8 emu g−1, which decrease with the increase of the usage amount of DVB. The addition of DVB is beneficial to the formation and stability of the ion imprinted cavity of Fe3O4@IIPs. The effects of the solution pH value, initial concentration of ClO4−, and adsorption time on the adsorption properties of ClO4− in aqueous solutions were investigated. The results show that the adsorption capability is affected significantly by solution pH value and reaches the maximum adsorption capacity at pH 3.0. The best adsorption capacity and selectivity of Fe3O4@IIPs to ClO4− can be obtained when the usage amount of DVB is at 0.5 g for synthesis. The adsorption mechanisms might include both ion exchange and electrostatic interaction. The isothermal adsorption curves mainly obey the Langmuir model with the theoretical maximum adsorption capacities (qm,c) at 76.92–111.1 mg g−1 and the experimental maximum adsorption capacities (qm,e) at 75.7–108.9 mg g−1, respectively, which are much higher than those of the non-ion imprinted material (Fe3O4@NIP, qm,NIP: qm,c at 60.61 mg g−1 and qm,e at 59.0 mg g−1). The adsorption kinetic studies show that the adsorption processes reach equilibrium within 10 min and the kinetic data are well fitted to the pseudo-second-order model. There is almost no interference by the coexisting anions for the selective adsorption of ClO4−, with a imprinting factor (α) at 1.8, and selectivity factor (β) larger than 5.9 for several kinds of common co-existing anions, respectively. The Fe3O4@IIPs are ideal candidates for removal of ClO4− from aqueous solution.

In this article, the preparation of bis-imidazolium hydrogen sulfate and bis-imidazolium perchlorate as two new bis-dicationic Bronsted acidic ionic liquids based on imidazole is reported. After characterization by FT-IR, mass and NMR spectroscopy and pH titration, the applicability of these reagents is studied in the promotion of the synthesis of 5-arylidene barbituric acids and pyrano[2,3-d] pyrimidinone derivatives. These methods possess some advantages such as ease of preparation of the catalyst, simple work-up procedure, short reaction times, excellent yields, and use of nonorganic solvents during all steps of the reactions and good reusability of the catalysts.

The use of small molecules as chemosensors for ion detection is rapidly gaining popularity by virtue of the advantages it offers over traditional ion sensing methods. Herein we have synthesized a series of acridine(1,8)diones (7a–7l) and explored them for their potential to act as chemosensors for the detection of various anions such as fluoride (F−), acetate (OAc−), bromide (Br−), iodide (I−), bisulfate (HSO4−), chlorate (ClO3−), perchlorate (ClO4−), cyanide (CN−), and thiocyanate (SCN−). Acridinediones were found to be highly selective chemosensors for fluoride ions only. To investigate in detail the mechanism of selective fluoride ion sensing, detailed spectroscopic studies were carried out using UV-visible, fluorescence and 1H NMR spectroscopy. Fluoride mediated (NH) proton abstraction of acridinedione was found to be responsible for the observed selective fluoride ion sensing. Quantum mechanical computational studies, using time dependent density functional theory (TDDFT) were also carried out, whereupon comparison of acridinedione interaction with fluoride and acetate ions explained the acridinedione selectivity for the detection of fluoride anions. Our results provide ample evidence and rationale for further modulation and exploration of acridinediones as non-invasive chemosensors for fluoride ion detection in a variety of sample types.