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We prepared and characterized an array of polarity-sensitive fluorescent dyes (7 and 9a, 9b and 9c). Fluorescent dyes are based on imidazole cores, suitably functionalized with a conjugated push–pull system. The photophysical properties of the synthesized materials were elaborately investigated. These new fluorescent probes showed good fluorecence emission, higher φFl values and large Stokes shifts in different organic solvents because of their ICT nature. Furthermore, with aldehyde groups as the recognition sites, all the dyes could act as ratiometric fluorescent sensors towards methanol. The selective ratiometric fluorescence response towards methanol is due to the strong intermolecular H-bonding between the aldehyde unit and methanol. The detection limit of methanol was found to be at the ppm level. Methanol sensing was confirmed using emission spectroscopy, FTIR studies and theoretical calculations. Additionally, these dyes were used for the detection of methanol in biodiesel and in test paper strips. [ABSTRACT FROM AUTHOR]

There are some notable drawbacks of ordinary magnetic effervescent tablets including their quick disintegration, hygroscopicity, and impracticability for field use. In order to solve the above problems for further extraction and preconcentration of three phenolic pesticides from crop flour samples, an effervescent tablet-assisted acidic ionic liquid-based in situ solvent formation magnetic solid-phase extraction (ETA-AIL-MSPE) technique was developed. In contrast to conventional imidazole ionic liquids, acidic ionic liquids can be employed as an acid source for effervescent processes in addition to being used as extractants. Not only does this reduce the need for organic solvents, but the production of CO2 by the effervescent tablet also provides a rapid dispersion effect, removing the requirement for further dispersion stages and streamlining the experiment. The magnetic effervescent tablet is made of Na2CO3 as an alkaline source, [BMIM][HSO4] as extractant and acidic sources, NaCl as a viscosity modifier, and Fe3O4 as magnetic nanoparticles. The Plackett–Burman design and the central composite design were used to screen and optimize three key variables (93 mg of Na2CO3, 451 mg of AIL, and 37 mg of Fe3O4), respectively. Through the integration of high-performance liquid chromatography-diode array detection (HPLC-DAD), the ETA-AIL-MSPE technique provided enhanced recoveries of 85.0–107.2% and limits of detection of 0.14–0.17 μg kg−1 for three representative species (ioxynil, bromoxynil, and dinoseb) in four different types of crop flour samples. For both intra-day and inter-day precision, the relative standard deviations were below 7.7%. Generally, the recently developed technique is convenient, efficient and environmental-friendly, and it has great potential for on-site sample preparation for the detection of phenolic pesticides in crop flour samples. [ABSTRACT FROM AUTHOR]

Nitrogen-based heterocycles such as pyrazole, imidazole, 1,2,4-triazole, benzimidazole, and benzotriazole substituted fused pyran derivatives (6a–e, 8a–e, 10a–e, 12a–e, & 14a–e) have been synthesized and tested for their in vitro anticancer efficacies against MCF7, A549, and HCT116 cancer cell lines. Among the compounds, 6e, 14b, and 8c were identified as the most potent against MCF7, A549, and HCT116, with IC50 values of 12.46 ± 2.72 μM, 0.23 ± 0.12 μM, and 7.58 ± 1.01 μM, respectively. Further studies demonstrated that these compounds can change cellular and nuclear morphology and inhibit colony formation in the tested cancer cells. They also remarkably block/inhibit the cell cycle progression of cancer cells at various phases. DNA damage analysis and apoptosis studies revealed that these compounds have the potential to induce DNA double-strand breaks and apoptosis. In silico absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties of the potent compounds were assessed, revealing that all the compounds exhibited favorable pharmacokinetic and toxicological properties. The potent compounds identified from this study can be considered as a lead for further drug design and development. [ABSTRACT FROM AUTHOR]

The design and development of smart materials in developing advanced sensing platforms for volatile organic compounds (VOCs) have attracted increasing attention. π-Conjugated small organic building blocks, which can self-assemble into well-ordered superstructures, offer multiple advantages of high surface area, unique optoelectronic properties, good chemical/thermal stability, and host–guest interaction ability, which make them appealing candidates for VOC sensing. However, the fabrication of stable and well-ordered self-assembled structures from π-conjugated building blocks with appreciable electrical properties and their successful employment in the selective detection of VOCs remains a challenge due to the non-specific interaction between monomers during self-assembly and with other existing VOCs during sensing, respectively. Herein, we have designed and synthesized three phenanthro[9,10-d] imidazole-based ligands; L1, L2, and L3 with three different hydroxy benzene analog substitutions at the 2-position and their corresponding Zn(II) and Cd(II) complexes followed by fabrication into well-ordered superstructures with discrete morphologies for the selective detection of acetone vapour by measuring the contact potential difference using the Scanning Kelvin Probe (SKP). Several experimental analyses suggest that a precise combination of the operative non-covalent interactions along with the metal–ligand interactions drive the overall self-assembly process of these metal coordinated π-conjugated probes and could lead to generation of well-ordered various superstructures. Surface photovoltage measurements using the SKP on the surfaces of films coated with superstructures derived from these metal complexes were carried out both in the dark and under UV (Ultra-Violet) illumination in the presence of different vapours of VOCs. As per the results, under UV illumination, the thin film fabricated with superstructures derived from Cd complexes ((L1)2M, (L2)2M and (L3)2M; M = Cd(II)) exhibit higher sensitivity and selectivity towards acetone in comparison with Zn(II) complexes-based superstructures. Thus, these self-assembled structures generated by the metal complexes of these π-conjugated molecular probes may provide new insights into the fabrication of organic electronic devices for gas sensors. [ABSTRACT FROM AUTHOR]

The development of carbon-based catalysts to substitute Pt-based catalysts for the oxygen reduction reaction is highly important for promoting their practical application in energy conversion. Herein, we prepare Zn, Fe and N-codoped porous carbon (Zn/Fe-NC-x) as a cathode catalyst via a facile one-step pyrolysis predesigned bimetallic zeolitic imidazole framework. Systematic electrochemical studies demonstrated that the synthesized Zn/Fe-NC-0.5 exhibits higher electrocatalytic activity towards the oxygen reduction reaction. In particular, Zn/Fe-NC-0.5 has a smaller charge transfer resistance, larger exchange current density, and much higher open circuit potential and mainly proceeds via an efficient four-electron pathway. A microbial fuel cell equipped with the synthesized catalyst exhibited the highest maximum power density of 1954 ± 20 mW m−2. In addition, the effects of the iron doping content on the oxygen reduction reaction performance and maximum power density were evaluated: a moderate Fe doping content plays a crucial role in improving the catalytic activity, and the synergistic effect of Zn, Fe and N codoping promotes cathodic performance. In brief, Zn/Fe-NC, which has the advantages of facile synthesis, environmental friendliness and excellent electrochemical activity, is a promising Pt-alternative catalyst for the oxygen reduction reaction in air-cathode microbial fuel cells. [ABSTRACT FROM AUTHOR]

The nature of π-hole spodium bonds in the HgLCl2⋯ZH3/CH2Y complexes (L = pyrrole 1, pyrazole 2, imidazole 3, pyridine 4, pyridazine 5, and pyrimidine 6; Z = N, P, As, and Sb; Y = O, S, Se, and Te) has been studied using theoretical calculations. The electrophilicity of the π-hole in the tri-coordinated HgII complexes varies with the type of N-heterocyclic ligand. The strength and nature of the π-hole spodium bond is closely related to the properties of the Lewis bases. In the case of HgLCl2⋯ZH3, the strength of the π-hole spodium bond weakens as the nucleophilicity of the base decreases, following the sequence HgLCl2⋯NH3 > HgLCl2⋯PH3 > HgLCl2⋯AsH3 > HgLCl2⋯SbH3. The Hg⋯Z spodium bonds change from a partially covalent interaction to a close-shelled noncovalent interaction. The nucleophilic ability of CH2Y decreases in the order CH2O > CH2S > CH2Se > CH2Te, while the strength of the π-hole spodium bond follows the order HgLCl2⋯OCH2 < HgLCl2⋯SCH2 < HgLCl2⋯SeCH2 < HgLCl2⋯TeCH2. The Hg⋯Y spodium bond undergoes a transition from a close-shelled noncovalent to a partially covalent interaction, resulting in an incremental increase in the degree of covalence. The Hg⋯Te spodium bond exhibits certain characteristics resembling those of a coordinate covalent bond. The inter-orbital interactions observed in the formation of the HgLCl2⋯YCH2 complexes appear to be significantly stronger compared to those observed in the HgLCl2⋯ZH3 complexation. [ABSTRACT FROM AUTHOR]

With a rapid expansion in applications of epoxy resins (EP) and derived composites, there is a high demand for improving their flame retardant and dielectric properties. In this work, a facile and convenient strategy for loading a dimethyl methylphosphonate (DMMP) flame retardant into the channels of ZIF-8 (zeolitic imidazolate framework) was developed, followed by the assembly of a hybrid ZIF-8@DMMP material with epoxy resin (EP). The obtained MOF-containing hybrid EP composites, abbreviated as 820/EP (with 20 wt% ZIF-8) and 8 FR20/EP (with 20wt% ZIF-8@DMMP), were fully characterized and shown to feature superior flame retardant behavior, contributing to an enhanced safety of such material in terms of total smoke suppression, lower levels of total heat release and carbon monoxide generation. The results demonstrated that the formation of an intumescent dense char layer restrained further combustion, thus enabling this composite material to feature a better flame retardant performance. Besides, the composite exhibited a dielectric permittivity and dielectric loss of as low as 3.0 at a high frequency, which significantly outperforms the neat epoxy resin. This work thus showcases a simple and efficient route to enhance dielectric and flame retardant properties of polymeric epoxy resins, while merging the inherent porosity of ZIF-8 and traditional flame retardant behavior of DMMP. [ABSTRACT FROM AUTHOR]

Environment-benign one-pot three-component cycloadditions of diazo compounds, nitrosoarenes and vinyl pyrimidines, or vinyl purines, or vinyl imidazoles, or vinyl triazoles or vinyl indole have been developed. This catalyst- and additive-free strategy could efficiently introduce the isoxazolidine skeleton into nucleoside analogues, oxazole molecules and indole derivatives to provide diverse classes of isoxazolidinyl pyrimidine nucleoside analogues, isoxazolidinyl purine nucleoside analogues, isoxazolidinyl imidazoles, isoxazolidinyl triazoles and isoxazolidinyl indole with moderate to good yields for most substrates. [ABSTRACT FROM AUTHOR]

A series of 6-oxo-3-(1,2,4,5-substituted-1H-imidazol-3-ium-3-yl)-3,6-dihydro-1,2,4,5-tetrazin-3-ides (3a–3z, 3aa–3ak) was synthesized with medium to good yield by the reaction of 3,6-dichloro-1,2,4,5-tetrazine with a variety of substituted imidazoles in the presence of trace water in solvents. The quinoidal-like structure of these compounds was demonstrated via spectroscopic methods, X-ray diffraction techniques, and computational chemistry. Additionally, water–18O was used to prove that the oxygen in tetrazinone comes from the water in solvents via high-resolution mass spectrometry (HRMS). Moreover, a possible mechanism of aromatic nucleophilic substitution is proposed. [ABSTRACT FROM AUTHOR]

Metal ions of the later part of the first-row transition series (Fe, Co, Ni, Cu, and Zn) can form bonds through the carboxylate, hydroxyl, thiol, and imidazole side chains of proteins and those bonds are significantly more stable than those formed by non-transition metals. Their adventitious binding to protein surfaces provides a great platform for maintaining the native structure of many biologically significant proteins and thus inhibiting the self-aggregation phenomenon of proteins. Aggregation followed by deposition of proteins used for therapeutic purposes either at the site of administration in vivo or during storage conditions in vitro is a major concern. In this work, human insulin is induced to form 'amyloid fibrils' at acidic pH and elevated temperature and then the inhibitory activities of two transition metal ions Fe3+ and Cu2+ towards insulin amyloid fibrillation were investigated. The results show that the formation of β-sheet-rich fibrillar structures was inhibited more with Fe3+ than Cu2+-treated insulin. Dynamic light scattering and circular dichroism proved that Cu2+ was effective at lowering the interaction ratios with insulin, yet Fe3+ was effective in maintaining the size as well as the alpha-helical conformation of monomeric insulin. This metal complex (insulin-Fe3+ or insulin-Cu2+) delayed the nucleation step of aggregation and Fe3+ is far better than Cu2+ in this endeavor. However, both of the metal ions proved their effectiveness in preventing amyloid fibrillation in vitro and can modulate the morphology of the aggregates as revealed by TEM studies. Overall the two transition metal ions Fe3+ and Cu2+ employed in this investigation are essential micronutrients too and are required in minute concentrations. The present study will encourage the applications of transition metal ions Fe3+ and Cu2+ as effective interrupters of amyloidogenesis in aggregation-prone proteins showing pathogenic amyloid deposition. [ABSTRACT FROM AUTHOR]

Salen-based octahedral trans metallo-salen complexes with monodentate co-ligands may exist as several conformational isomers, including stepped and umbrella shaped conformations. However, the factors governing the selective isolation of a particular conformer have not been investigated properly. In this report, six mononuclear cobalt(III) complexes (1–6) with a tetradentate salen-type Schiff base ligand, N,N′-bis(3-methoxy-5-methylsalicylidene)-ethane-1,2-diamine (H2L), and different heteroaromatic co-ligands (pyridines, imidazole and pyrazole) have been synthesized and characterized to unveil the influence of heteroaromatic co-ligands on the conformational (stepped versus umbrella) selectivity of the resulting complexes. X-ray crystallography reveals that the structures of 1–6 are eventually similar with only differences in the coordinated heteroaromatic moieties at axial positions and the accommodation of a different number of lattice solvent/guest molecules in the crystal voids. Interestingly, although a landscape of intermolecular non-covalent interactions are present in the solid state in these systems, the pyridyl co-ligands exclusively stabilize the umbrella-shaped conformation, while five-membered heteroaromatic bases prefer the stepped-shaped conformation, disclosing that the different degrees of intramolecular interactions (repulsion/attraction) of the six and five membered heteroaromatic ligands at the axial positions play the most important role in the selective stability of the different conformations in the solid state. All these complexes exhibit efficient catalytic activity mimicking the functions of phenoxazinone synthase and catechol oxidase. The catalyst recyclability test was also performed and it showed a very negligible change in catalytic efficiency even after five catalytic cycles. Theoretical calculations were performed to gain in-depth understanding of the preference of pyridine ligands for the umbrella-shaped conformation and the five-membered ring co-ligands for the stepped-shaped one, as well as for the mechanistic investigation of the aerobic oxidation of o-aminophenol in the presence of 1–6 as catalysts. [ABSTRACT FROM AUTHOR]

A new three-dimensional (3D) framework with the general formula {[Cu(μ3-dmg)(im)2]·3H2O}n (1) was synthesized using an aliphatic dicarboxylic acid linker 2,2-dimethylglutarate (dmg2−) and nitrogen-containing imidazole ligand (im) under conventional methods. 1 was characterized by FT-IR spectroscopy, elemental analysis, single crystal and powder X-ray diffractions, and thermal analysis techniques. Additionally, the optical and topological properties of compound 1 were also investigated. The single crystal X-ray data exhibit that 1 is an interesting 3D framework and it has a I41/a space group, which originates from two imidazole ligands, one dmg and three lattice water molecules. Topologically, 1 displays a lvt-a topology with the point symbol of {4.8.10}. In addition, the catalytic activity of compound 1 was investigated in the CO2 conversion into cyclic carbonates. It was found that compound 1 was an active catalyst even at low catalyst loading under 0.1 MPa CO2 at 80 °C. The yields of 23–99% were obtained. Compound 1 can be recycled at least four times without significant compromise in the activity in the first three catalytic reactions. [ABSTRACT FROM AUTHOR]

The p38 mitogen-activated protein kinase (MAPK) is a crucial target for chronic inflammation. Here, 2D-QSAR and molecular docking studies were performed on a new series of pyridinyl imidazole derivatives as p38α MAPK inhibitors. The goal is to find a correlation between the chemical structures and inhibitory activity of the p38α MAPK. The partial least squares (PLS) regression method was used to build the 2D-QSAR model. The results revealed that the generated model yielded 0.85 for the determination coefficient (r2), 0.83 for the adjusted determination coefficient (ra2), and 0.16 for the root-mean-square error (RMSE). Internal and external validations were used to figure out how well the model could predict the future. The rcv2 and rtest2 values were 0.78 and 0.92, indicating that the developed model is robust and capable of predicting the activity of new compounds. The affinity of the ligands (pyridinyl imidazole derivatives) and the binding pocket of the p38α MAP kinase receptor was also determined by molecular docking using autoDock tools. The results revealed the importance of conventional hydrogen bonds in the binding pocket of the p38α MAPK receptor. Based on these results, a novel series of compounds were predicted and evaluated using molecular dynamics (MD) and ADMET prediction investigations. The study's findings might pave the way for the development of new pyridinyl imidazole derivatives that are able to inhibit the enzymatic activity of the p38α MAP kinase. [ABSTRACT FROM AUTHOR]

In this paper, PS (polystyrene)/Au/ZIF-8 (zeolite imidazole framework-8) hybrid structures were synthesized for the first time as novel SERS active substrates. A series of substrates were successfully prepared by changing the Au sputtering time (5 min, 8 min, 10 min, 15 min and 20 min). When the sputtering time of Au was 10 min, the 4-mercaptobenzoic acid (4-MBA) molecules on the PS/Au/ZIF-8 substrate exhibited the maximum SERS enhancement. Meanwhile, the hybrid SERS substrate exhibited good SERS reproducibility, and we successfully obtained an ultrahigh enhancement factor of 1.67 × 106. Probe molecules can be easily enriched on the surface of the PS/Au/ZIF-8 composite due to their large pore volume and the high surface area of metal organic framework (MOF) materials. ZIF-8 also guides the probe molecules to the "hot-spots" to enhance the SERS signals. Moreover, the detection limit of R6G molecules achieved was 10−12 M when PS/Au(10 min)/ZIF-8 was used as a highly sensitive SERS sensor. This strategy has brought new insights to SERS research, and has also provided a new idea for the application and development of SERS in MOF-based SERS materials and ultra-sensitive analyses. [ABSTRACT FROM AUTHOR]

The merging of fundamentally and biologically important heterocyclic structures, such as pyrroles, indoles, and imidazoles, in molecules of dihydropyrrolo[1′,2′:3,4]imidazo[1,2-a]indoles functionalized by E-acylethenyl groups was achieved in water on the platform of commercial 3H-indoles using readily available acylpyrrolylacetylenes as additional building blocks. The yields of the ensembles reached 88% (100 °C, 8 h), which is noticeably better than that produced using conventional solvents (MeCN, MeNO2, DMSO, and CF3CH2OH), wherein the reaction proceeds at a rate of approximately 10 times longer (96 h) with lower yields of the target products (not higher than 80%). The reaction presumably proceeds in a micellar-like microreactor self-assembled in a two-phase aqueous medium that secures favorable mutual orientation of the merging molecules, providing a facile [2+3] concerted cycloaddition to finally form fused polyheterocyclic systems. The performed DFT calculations are in agreement with such mechanistic considerations, particularly those underlying the crucial role of water in the studied cascade process. [ABSTRACT FROM AUTHOR]

Two new bis-ferrocene (Fc) conjugated Y-shaped imidazole (IM) based donor–π–acceptor [(D–π)2–IM–π–A] type "push–pull" compounds [(Fc–CH＝CH)2–IM–C8H17–C6H4–R] {R = COOC2H5 (1); COOH (2)} have been synthesized for second-order nonlinear optics (1, ester) and dye-sensitized solar cell (2, acid) applications. The redox potentials of the compounds were examined using cyclic voltammetry, which shows one-electron charge transfer from the ferrocene to ferrocenium ion (Fe2+ Fe3+), and these potentials were employed to calculate the related energy gap. The second-order nonlinear optical (NLO) properties of the ester compound 1 were explored using the Electric-Field-Induced Second Harmonic generation (EFISH) technique in CHCl3 solution with an incident wavelength of 1907 nm, and it shows an interesting μβEFISH value of −780 × 10−48 esu. Besides, the carboxylic acid compound 2, adequately functionalized for anchoring to TiO2, was tested as a photosensitizer in dye-sensitized solar cells (DSSCs) with non-corrosive Cu(I)/Cu(II) complexes as the redox mediator. Although the photovoltaic performance of 2 attached to TiO2 in a DSSC device is rather limited (JSC = 1.51 mA cm−2, VOC = 404 mV, FF = 42.7, η = 0.26%), it confirms the potential of ferrocenyl conjugated D–π–A systems as photosensitizers. In addition, frontier molecular orbital levels, ground and excited state dipole moments (μg and μe), and the origin of electronic absorption spectra were studied by using density functional theory (DFT) with the B3LYP method using 6-31+G** as the basis set. [ABSTRACT FROM AUTHOR]

Barbituric acids are a useful tool for the construction of various supramolecular compounds with intriguing physicochemical properties. Also, barbiturates play a significant role in biology and medicine. The same is true for imidazole derivatives. Herein, three novel salts of barbituric (H2BA) and 2-thiobarbituric (H2TBA) acids with imidazole (Im), namely imidazolium barbiturate in two polymorphic modifications, HIm(HBA) (1) (pale yellow) and (2) (pale orange), and imidazolium 2-thiobarbiturate, HIm(HTBA) (3), were synthesized and characterized by CHNS elemental analysis, single-crystal and powder X-ray diffraction, FT-IR and UV-Vis spectroscopy techniques. Crystal structure analysis revealed that the compounds feature three different supramolecular architectures with the formula unit count (Z′) varying from 1 for 3 to 4 for 1, which is governed by an unusual geometry of hydrogen bonding motifs. Intermolecular interactions in crystals 1–3 were analyzed using 2D-fingerprint plots derived from the Hirshfeld surfaces. According to the TG-DSC analysis, compounds 1–3 were thermally stable up to ∼100 °C in air. The solubility studies (solubility product constants and solubility at a fixed pH value were determined) showed that salts 2 and 3 were more soluble in water than H2(T)BA. To the best of our knowledge, this is one of the first reports on the phenomenon of polymorphism among organic salts with barbiturate moieties. Thus, the present findings broaden our understanding of the supramolecular organization of barbiturates, complement the systematic studies of the correlation between their crystal structure and physicochemical properties and lay the foundation for the further development of novel materials based on imidazolium (2-thio)barbiturates. [ABSTRACT FROM AUTHOR]

Two luminescent Re(I) complexes, namely mononuclear fac-[ReCl(CO)3(TT-Py)] (1) and hexanuclear [{Re(μ-Cl)(CO)3(μ-TT-Py)}{Re2(μ-Cl)2(CO)6}]2 (2), were isolated in high yields by a one-pot reaction between [ReCl(CO)5] and different amounts of nitrogen-rich 2-pyridine cyclic triimidazole (TT-Py), which acts as a chelating ligand in both derivatives. The metallo-supramolecular cyclic structure of 2, which can be described as a metallacycle in which two mononuclear units of 1 act as bridging ligands towards two "Re2(μ-Cl)2(CO)6" fragments, was confirmed by single-crystal X-ray diffraction analysis. Both complexes were fully characterized in solution by 1D and 2D multinuclear NMR spectroscopy. 1 and 2 exhibit photoluminescence at room temperature in solution, with a broad unstructured emission in the 530–570 nm range. The nature of the excited states involved in the electronic absorption spectrum of 1 was ascertained by a combined density functional theory and time-dependent density functional theory (TD-DFT) study. Both compounds exhibit strong aggregation induced emission enhancement (AIEE), which is more pronounced for 2 leading to a solid state photoluminescence quantum yield of 2.5% that is one of the highest values ever reported for Re(I) polynuclear metallacycles so far. The versatility of TT-Py to adopt variegated coordination modes, previously observed for Cu(I) and Cu(II) derivatives, is confirmed supporting further use of this ligand to obtain new and peculiar emissive mono-, polynuclear and extended coordination systems. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDHs) are battery-type supercapacitor electrode materials with application potential due to their abundant active metal sites and surface functional groups. The traditional LDH structure easily aggregates and collapses. In this work, a stable cobalt zeolite imidazole framework (Co-ZIF) was used as the derived template to grow LDH nanosheets in situ to increase the contact area with the electrolyte, and polyaniline (PANI) acted as a conductive bridge to provide a rapid charge transfer pathway. The fabricated NiCo-LDH@PANI hollow structure demonstrated a specific capacity of 1315 C g−1 at 1 A g−1 and achieved a rate capacity of 951 C g−1 at 20 A g−1. Furthermore, the battery–supercapacitor hybrid device (NiCo-LDH@PANI//AC) exhibited an high energy density of 66.2 W h kg−1 at a power density of 800 W kg−1 with 95.5% capacitance retention after 20 000 cycles. [ABSTRACT FROM AUTHOR]

In this paper, we have demonstrated the facile synthesis of stable gold nanoparticles (AuNPs) using imidazolium ionic liquids (ImILs) as a stabilizer as well as a surfactant and their surface plasmon resonance (SPR) in different molecular solvents with varying dielectric properties. The preparation of AuNPs capped with N,N′-dialkyl ImILs of different chain lengths (denoted as [C4,Cn-im]Br, n = carbon number of the alkyl chain) has been investigated. With one long alkyl chain (n≥ 14), these AuNPs could be stably dispersed in solution over a month. The amphiphilic nature of the imidazolium salt dictates the stability and dispersion of these AuNPs in organic or aqueous solvents. Alkyl chain lengths (n≥ 14) and the amount of ImILs have insignificant effect on the size of AuNPs and they possess an average size of 5 nm. These ionic liquid stabilized AuNPs were exploited to examine their optical properties when exposed to various solvent systems by measuring the change in the SPR spectrum. It was seen that the position of the SPR band of AuNPs is greatly influenced by the solvents under consideration. The shift in the SPR absorption band is observed to be in the range of 520 nm to 605 nm for AuNP@[C4,C16-im]Br from nonpolar to highly polar solvents. The considerable discovery presented here is that the λSPR of the SPR shifts to the blue with the increase of carbon atom in the alcohol chain from methanol to 1-decanol. Also for polyethylene glycols (PEGs), the λSPR shifts to the blue with the increase in molecular weight from PEG 200 to PEG 600. In above both cases, the variation in SPR of AuNPs is observed according to the dielectric properties of the medium in addition to the steric factor of alcohols and PEGs during their interaction with AuNP surfaces. [ABSTRACT FROM AUTHOR]

We describe the synthesis of a symmetrical N,N′-bis(3-(1H-imidazol-1-yl)propyl)oxalamide-based receptor OX(PID)2 and its characterization by different physicochemical techniques, namely FT-IR, 1H and 13C NMR, TGA, and mass spectrometry. Single crystal X-ray diffraction analysis shows that OX(PID)2 crystallizes in monoclinic space group P21/c. The sensing capability of OX(PID)2 towards various cations has been exhaustively investigated using UV-vis and fluorescence spectroscopy. OX(PID)2 shows high selectivity and sensitivity towards Cu2+ and Fe3+ ions with a 1 : 1 binding ratio over other metal ions, which was highly supported via Job's plot and density functional theory calculations. The Cu2+ and Fe3+ ions induce the 'turn-off' signal when interacting with OX(PID)2. Moreover, using four different bacterial species, including S. aureus, B. subtilis, E. coli, and K. pneumonia, the biological activities of the newly created oxalamide-based compounds were assessed against various pathogenic bacteria and compared to streptomycin as a reference drug. Our substances exhibit moderate to good vital action against the aforementioned harmful microorganisms, according to the results. Then, fluorescence imaging in MDA-MB-231 on receptor OX(PID)2 suggested that OX(PID)2 had great potential in the application of bioimaging. The receptor with Cu2+ or Fe3+ ions was found to be cytotoxic against MDA-MB-231 and could be used as an anticancer agent. [ABSTRACT FROM AUTHOR]

Herein, we have realized an efficient and solvent-tunable Rh(III)-catalyzed [5+2] annulation of N-benzo[d]imidazole indolines with 2,2-difluorovinyl tosylate that presented an unusual 1,2-regioselectivity for the chemodivergent construction of monofluorinated and gem-difluorinated benzodiazepines, which are defined as potent anti-tumor agents against different cancer cell lines. In general, this work provides a powerful complement to both C–H activation chemistry and anti-tumor lead discovery. [ABSTRACT FROM AUTHOR]

In this study, zeolitic imidazole framework-8/cellulose membrane (ZIF-8/CM) was fabricated through an in situ synthesis method. The composite was installed in a dismountable filter and used as a sorbent for lab-made microextraction in packed syringe (MEPS). The entire MEPS procedure can be performed through simple operation of filtration, since the macroporous cellulose membrane was introduced as the substrate for ZIF-8 powder. Coupled to a high performance liquid chromatography tandem ultraviolet detector (HPLC-UV), the proposed method was applied for the analysis of tetracyclines in water samples. The extraction parameters, including the adsorbent type, sample solution pH, sample volume, type and volume of the elution solvent, were systematically studied. Under optimized conditions, desirable linearity (r > 0.99 for three analytes), high sensitivity (limit of detection: 0.1373–0.8917 μg L−1), good precision (RSD < 6.3%) and ideal recovery (72.9–97.6%) were obtained. The proposed method was demonstrated to be efficient, easily operative and environmentally friendly. [ABSTRACT FROM AUTHOR]

A series of N1-functionalized imidazoles have been synthesized in very good yield. Due to their amphoteric nature, they selectively discriminate among different nitroaromatic compounds. The fluorescence spectra of all the luminophores are highly sensitive towards picric acid compared to other nitroaromatic compounds. The fluorescence method has a fast response, low cost, and high selectivity for picric acid over other nitroaromatic compounds. Electrochemical analysis was performed and verified using DFT calculations. The electrochemical properties were studied using cyclic voltammetry to calculate the HOMO–LUMO gap, and were also confirmed via theoretical study. The Stern–Volmer quenching constant and detection limit were found to be 6.68 × 106 M−1 and 446 ppb. The capability of luminophores to recognise picric acid was estimated using fluorescence, DFT analysis, and 1H NMR spectroscopy. Thus, potential luminophores were synthesized as convenient and promising multifunctional sensors for toxic and explosive nitroaromatic analytes. [ABSTRACT FROM AUTHOR]

A novel metal complex redox material is synthesized via coordinating the iron metal site with 1-(naphthalen-2-ylmethyl)-2-(pyridin-2-yl)-1H-benzo[d]imidazole (npbi) ligands, herein named as Fe2+/3+ [npbi]3. The as-synthesized Fe2+/3+ [npbi]3 redox material has a good redox potential (0.43 V vs. NHE), low Gibbs free energy (1.86 eV), low reorganization energy (1.90 eV), high diffusion coefficient and less driving force in an electrolyte system for dye sensitized solar cell (DSC) and supercapacitor (SC) applications to accomplish huge quasi-reversible redox operations between the electrode/electrolyte interfaces of the devices. Interestingly, the DSC with the Fe2+/3+ [npbi]3 electrolyte and an organic dye achieved a conversion efficiency of 2.96% under 1 sun illumination. This high power efficiency is attributed to a potential matching of this redox system with the organic dye, which can diminish the recombination reactions and improve the open circuit voltage (OCV) of the DSC. At the same time, the addition of Fe2+/3+ [npbi]3 in a symmetric SC with a H2SO4 electrolyte and graphene oxide electrodes contributes to an additional Faradaic reaction (electro-sorb mechanism) at the electrode/electrolyte interface. This results in the corresponding SC displaying a high energy density of 29.79 W h kg−1 at a power density of 719 W kg−1 and long charge/discharge stability for 11 000 cycles with 97.4% capacity retention respectively. Overall, this study offers new insights on designing appropriate transition metal complex redox materials for both DSC and SC applications with boosted efficiencies. [ABSTRACT FROM AUTHOR]

Achieving deep blue thermally activated delayed fluorescent (TADF) materials with narrow emission still remains a challenge. Herein, two deep blue TADF emitters DCBTRZ and PPCTRZ were designed and synthesized by directly using host materials, 1,4-di(carbazol-9-yl)benzene (DCB) and 2-[4-(9H-carbazol-9-yl)phenyl]-1-phenyl-1H-phenanthro[9,10-d]imidazole (PPC) as donors, and 2,4,6-triphenyl-1,3,5-triazine (TRZ) as an acceptor. The two emitters have typical TADF properties. Both of them can emit deep blue fluorescence with a very narrow full-width at half-maximum (FWHM) of 42 nm in toluene. The photoluminescence quantum yields (PLQYs) of DCBTRZ and PPCTRZ are 39.6% and 38.2% in doped films, respectively. Devices based on DCBTRZ and PPCTRZ achieve deep blue emission (440 and 442 nm) with maximum external quantum efficiencies (EQEmax) of 6.68% and 6.55%, respectively. Meanwhile, they exhibit very high color purity. The CIEy and FWHM of devices employing DCBTRZ and PPCTRZ are 0.059/0.063 and 56/54 nm, respectively, meeting the standard of NTSC for deep-blue emitters, which indicates excellent application prospects in displays. The results suggest that this strategy for developing deep blue TADF materials with narrow emission and CIEy < 0.06 directly employing host materials as donors is feasible and effective. [ABSTRACT FROM AUTHOR]

A new family of well-defined and fully conjugated oligoelectrolyte compounds were elaborated based on one or two bis-thiophene dialkoxyphenylene units. Di- or tetra-functionalized compounds with imidazolium, pyridinium and triethylammonium cationic species were synthesized in good yields. The effect of counteranions was also evaluated using iodide, chloride, fluoride and hexafluorophosphate anions. Their solubility was measured in apolar solvents (cyclohexane and chloroform) and polar protic solvents (water, ethanol, and isopropanol). A study of their thermal properties was conducted with TGA analysis showing a good stability up to 220 °C. Furthermore, their optical properties were examined and similar absorption properties were observed in solution and in the solid state. Most of these compounds exhibited significant fluorescence properties which were dependent on their involved counteranion and the solvent used. [ABSTRACT FROM AUTHOR]

It is necessary to recover precious metals from aqueous solutions because they have a wide range of applications. In this work, a poly(ionic liquid) (PIL) gel containing an imidazole group was fabricated using a radiation method and utilized for the capture of Au(III), Pt(IV), and Pd(II) ions. It was discovered that the PIL gel exhibited high adsorption efficiency for Au(III), Pt(IV), and Pd(II) in a wide pH range. The adsorption processes for target ions all reached equilibrium within 4 min. Meanwhile, the isotherm experiments revealed that the adsorption was in accordance with the Langmuir model, and the maximum adsorption capacities were 854.7 mg g−1 for Au(III), 420.2 mg g−1 for Pt(IV), and 277.8 mg g−1 for Pd(II). Furthermore, the PIL gel could selectively adsorb Au(III), Pt(IV), and Pd(II) from simulated acidic waste effluent containing Cu(II), Zn(II), Fe(III), and Ni(II). In particular, the PIL gel demonstrated its ability to selectively recover trace Au(III) from real gold slag leaching solution. FTIR and XPS analyses revealed that anion exchange was the dominant adsorption mechanism. [ABSTRACT FROM AUTHOR]

This work reports on the effect of the morphology of ZIF-67 on its performance as a non-enzymatic electrochemical uric acid sensor. Three different structures were prepared using a simple co-precipitation method with different solvents. The characterization studies on ZIF-67 were carried out by several techniques including X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The characterization results showed that ZIF-67 which was prepared using methanol, water, and a mixture of methanol and water displayed dodecahedral, microplate, and irregular shapes, respectively. The three different structures are denoted as Me-ZIF-67, W-ZIF-67, and M-ZIF-67, respectively. The uric acid sensor performances were evaluated by conducting Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV) measurements in PBS solution with a pH of 7.4 containing uric acid. The test results show that W-ZIF-67 has the highest electrocatalytic activity compared to the other two materials possessing the highest current and the lowest overpotential. As a uric acid sensor, W-ZIF-67 has a sensitivity of 0.0377 μA μM−1 cm−2 with a relatively wide linear detection range of 20–1000 μM, and a detection limit of 3.04 μM. W-ZIF-67 also has good reproducibility and is stable against interfering species such as urea, glucose, ascorbic acid, and NaCl. [ABSTRACT FROM AUTHOR]

New Y-shaped ferrocene (Fc)-conjugated trifluoromethyl-substituted imidazole (IM) donor–π–acceptor [(D–π)2–IM–D′–π–CF3] "push–pull" chromophores [(Fc–CH＝CH)2–IM–C6H4–R–C6H4–CF3] {R= –OCH3 (1); –N(C2H5)2 (2)} were synthesized and structurally characterized. The structure of the chromophores was confirmed via single-crystal X-ray diffraction studies. They crystallized in the triclinic P1¯ (for 1) and monoclinic P21/c (for 2) space groups. Thermogravimetric analysis (TGA) was used to study the thermal stability of chromophores 1 and 2, and it was found that both were stable at temperatures of about 300 °C. The redox properties were studied through cyclic voltammetry (CV), which revealed one-electron transfer from the ferrocene to ferrocenium ion (Fe2+ Fe3+), and their potentials were utilized to calculate their energy gaps, which were 2.16 eV for 1 and 2.12 eV for 2. The second-order nonlinear optical (NLO) properties of chromophores 1 and 2 were explored via electric-field-induced second-harmonic generation (EFISH) technique in CHCl3 solution with an incident wavelength of 1907 nm. μβEFISH values were −725 × 10−48 esu and −806 × 10−48 esu for 1 and 2, respectively. The μβEFISH values slightly decreased compared with other reported ferrocene-conjugated Y-shaped imidazole chromophores owing to their substitution on imidazole nitrogen, which increases steric hindrance and reduces the ICT process in the chromophores. In addition, their frontier molecular orbital levels, excited and ground state dipole moments (μe and μg), and electronic absorption spectra were studied using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) with the B3LYP method using the 6-31+G** basis set. [ABSTRACT FROM AUTHOR]

A 2-(2′-pyridyl)-imidazole (L) based water soluble nickel(II) complex of the type NiL2Cl2 (1) has been synthesized and characterized by spectroscopic, electrochemical, analytical and X-ray diffraction studies. Structural characterization of 1 shows a distorted octahedral environment around the nickel(II) center coordinated by two L ligands and two chloro ligands cis to each other. Intermolecular hydrogen-bonding, π⋯π interactions and C–H⋯π interactions have been investigated in detail. The irreversible electrochemical behaviour of complex 1 has been explained by considering the L-based proton-coupled-electron-transfer (PCET) mechanism. The labile nature of L and the chloro ligands in 1 is verified by substituting a biologically relevant quinonoid ligand 2,4-di-tert-butyl-6-(phenylamino)phenol, which leads to an inner-metallic chelate, 2. Furthermore, the antibacterial activity of the complexes 1 and 2 is tested against a few clinical bacteria suggesting their significant bactericidal properties relative to a standard antibiotic, ciprofloxacin. Prominent anticancer activity of 1 and 2 against human colorectal adenocarcinoma (HT-29) cancerous cell lines is also observed with IC50 33.5 and 45 μM, respectively, exhibiting the potential to produce promising cost-effective metallo-therapeutic agents. [ABSTRACT FROM AUTHOR]

Herein, two novel A–D–A structural imidazole derivatives, namely BMTPBZP and BMTPNKL, with orange and green fluorescence were successfully designed and synthesized, which exhibited an evident charge transfer (CT) excited state property. Compared with the triphenylamine-imidazole molecule TPA-BM with a simple D–A structure, which made the fluorescence red-shifted and quenched the response toward Fe3+, both BMTPBZP and BMTPNKL could selectively recognize Fe3+ based on the infrequent response of fluorescence enhancement and a blue shift with a relatively great sensitivity and anti-interference performance, suggesting that they have potential to be used as a novel fluorescence turn-on type Fe3+ sensor. The sensing mechanism study showed that the response of these two probe molecules toward Fe3+ could be attributed to the coordination reaction between Fe3+ and the electron-rich N atom on the imidazole ring in a 1 : 1 ratio, which caused the CT excited state of the probe molecules to generate a new and higher energy CT emission. In addition, the introduction of the A–D–A structure was demonstrated to be the key for obtaining the enhanced fluorescence and blue-shifted response of the probe molecules. [ABSTRACT FROM AUTHOR]

With the development of nuclear power, extraction of uranium from aqueous solutions using imidazole functionalized sorbents is extremely important for environmental protection and the sustainable development of atomic power since imidazole shows high selectivity for uranium. However, the uranium extraction capability of imidazole is frequently constrained because of the comparatively low coordination affinity of nitrogen atoms towards uranium, which seriously inhibits the practical use. Herein, a novel imidazole functionalized porous organic polymer adsorbent P(DVB-VIM) was facilely developed by solvothermal polymerization of vinyl imidazole (VIM) and divinylbenzene (DVB). Surprisingly, the maximum adsorption capacity (qmax) for uranium on P(DVB-VIM) was 689.6 mg g-1 with a good selectivity of 85.5% in aqueous solution containing 9 co-existing ions, suggesting that imidazole introduced by solvothermal polymerization not only demonstrated a high selectivity for uranium, but has a robust coordination affinity towards uranium. More importantly, the adsorbent could also be recycled for at least twenty cycles without any obvious decrease of its adsorption ability. The high adsorption efficiency for uranium was mainly attributed to the high content of accessible imidazole ligands, and increasing the concentration of imidazole would result in higher adsorption capacity, which was verified by the experimental results. Both XPS and DFT analysis confirmed that only the N atom in CQN of imidazole took part in uranium coordination. The result from DFT also revealed that the optimized geometric structures of 1: 2 of UO2 2+ with the two non-adjacent imidazole groups of the same polymer chain could describe the interaction of uranium with P(DVB-VIM). This work provided a feasible tactic to develop adsorbents with excellent uranium extraction efficiency for environmental protection and sustainable development of nuclear energy. [ABSTRACT FROM AUTHOR]

In this study, we developed a series of new aromatase MAO-B dual inhibitors against breast cancer. Aromatase inhibitors are the most commonly used drugs clinically for breast cancer. In this dual hybridization entity, the azole group acts as an aromatase inhibitor by binding to the HEM group of the enzyme and the thiazolylhydrazone group acts as an MAO-B inhibitor. The basic idea behind the development of this combination was to prevent the effect of aromatase inhibitor on dopaminergic neurons and to reduce its side effects due to decreasing estrogen level in patients with breast cancer. For this purpose, new hybrid derivatives containing the imidazole ring with known aromatase inhibitory activity and the thiazolylhydrazone structure with known MAO-B inhibitory activity were synthesized. From the obtained derivatives, compound 2e showed activity with an IC50 value of 0.079 ± 0.002 µM against the MCF-7 cell line. The aromatase inhibitory activity of compound 2e had an IC 50 value of 0.020 ± 0.002 µM, while letrazole inhibited the aromatase enzyme with an IC50 value of 0.021 ± 0.002 µM. In addition, 2e was also found to inhibit the DNA synthesis in the S phase of the cell cycle. In the flow cytometric study, the apoptotic potentials of the compounds were determined. On the side, compound 2e showed an inhibitory effect on the enzyme MAO-B with an IC 50 value of 0.045 ± 0.002 µM. Molecular docking studies were performed using aromatase, hMAO-B, and caspase-3 crystals to elucidate the interactions of the compounds with the active sites of the enzymes. [ABSTRACT FROM AUTHOR]

As sandwiched hole transporting material (HTM) layers are in direct contact with up-coated perovskite layers and bottom electrodes in p–i–n structured perovskite solar cells (i-PSCs), the film quality of HTMs determines the morphological properties of the perovskite absorbent. To achieve excellent surface morphology of HTM films, two asymmetric structured HTMs featuring methoxytriphenylamine electron donors and imidazole cores, were successfully developed through two simple reactions of cyclization and Buchwald–Hartwig coupling. DI-TPA was designed by incorporating an extra methoxytriphenylamine unit in the C2 site of the imidazole core, whereas an isolated benzene ring was introduced for DI–Ar. The asymmetrical conformation contributes to high glass transition temperatures and supports thermal-stable amorphous properties in both HTM films. Compared with DI–Ar, DI-TPA featuring with an extended backbone realizes more effective capability of hole extraction arising from the enhanced intermolecular π–π interaction in the solid state. Consequently, the i-PSC with DI-TPA as a dopant-free HTM generates an encouraging power conversion efficiency of 16.54%, significantly exceeding that with DI-Ar (13.77%). It should be noted that the efficiency is shown to outperform that of commercial dopant-free HTM PEDOT:PSS (13.41%) under the same condition. This work offers a fundamental strategy by reinforcing electron donation to improve the hole mobility of asymmetric HTMs for dopant-free p–i–n structured inverted PSCs. [ABSTRACT FROM AUTHOR]

Two coumarin-triarylimidazole hybrid derivatives with an N,N-diethylamine at the 7-position and a triaryl-substituted imidazole at the 3-position on the coumarin core, 3-(1-(4-(tert-butyl)phenyl)-4,5-diphenyl-1H-imidazol-2-yl)-7-(diethylamino)-2H-chromen-2-one (C-IM-Bu) and 3-(1-(4-cyanophenyl)-4,5-diphenyl-1H-imidazol-2-yl)-7-(diethylamino)-2H-chromen-2-one (C-IM-CN), were successfully synthesized for application in organic-light emitting devices. Their photophysical and electrochemical properties, thermal stability and electroluminescence properties were investigated. The results showed that these compounds have excellent thermal stability, and exhibit strong blue-green emission in dichloromethane solution and green emission in thin solid films. Further, the solution-processed doped devices based on the compounds were fabricated, in which the devices fabricated from C-IM-CN exhibited the best device performance with a turn-on voltage of 3.6 V, a maximum brightness of 6896 cd m−2, a maximum current efficiency of 6.39 cd A−1 and a maximum external quantum efficiency of 2.92%. [ABSTRACT FROM AUTHOR]

Three 2,7,12-trisubstituted triazatruxene derivatives containing different imidazole derived moieties, 5,10,15-tributyl-2,7,12-tris(4-(1-(4-(tert-butyl)phenyl)-1H-phenanthro[9,10-d] imidazol-2-yl)phenyl)-10,15-dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazole (2,7,12-TPI-TAT), 5,10,15-tributyl-2,7,12-tris(4-(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl)-10,15-dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazole (2,7,12-TBI-TAT) and 5,10,15-tributyl-2,7,12-tris(4-(1-(4-(tert-butyl)phenyl)-4,5-diphenyl-1H-imidazol-2-yl)phenyl)-10,15-dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazole (2,7,12-TIM-TAT), were synthesized by grafting different imidazole derived moieties with different electron-withdrawing abilities onto the 2-, 7- and 12-positions of a triazatruxene (TAT) core. A combination of thermal, photophysical and electrochemical characterization studies of these compounds was conducted to investigate the influence of different imidazole derived moieties on the optoelectronic properties of the compounds. Furthermore, solution-processed doped and nondoped devices based on the compounds were fabricated, in which the doped device of 2,7,12-TPI-TAT exhibited the best device performances, while the nondoped device of 2,7,12-TBI-TAT showed the best device performances. [ABSTRACT FROM AUTHOR]

Tetraphenylethylene functionalized arylimidazole derivatives G4, G3, G2, L-G4, L-G3 and L-G2 with different substituent groups and geometric structures have been designed and synthesized. All the compounds exhibited excellent aggregation-induced emission (AIE) properties due to the restricted intramolecular rotation (RIR) and the formation of J-aggregates. The solid compounds showed highly efficient emission with fluorescence quantum yields (ΦPL) of 67%, 72%, 67%, 40%, 52% and 48% for G4, G3, G2, L-G4, L-G3, and L-G2, respectively. The structure–property studies revealed that G4, G3 and G2 were more twisted structures and L-G4, L-G3 and L-G2 were partially planar conformations. The high quantum yields of the six solid compounds were driven by the synergistic effects of intramolecular electron transfer, molecular configuration and intermolecular interactions. On the other hand, the compounds also showed mechanochromism, acidochromism and picric acid-sensing properties. The compounds presented reversible mechanochromic behaviors between green and yellow emission and maintained highly solid emission (ΦPL about 50%) after grinding. The ΦPL values of the twisted molecules of G4, G3, and G2 decreased about 20% and those of the planar compounds showed a negligible change, which could be explained by the molecular structure planarization and the increased intermolecular interactions after grinding. Meanwhile, due to the excellent proton-binding properties of the imidazole group and pyridine group, the compounds were used as picric acid (PA) sensors with high selectivity and sensitivity in aqueous media and acid/base switches. The relative mechanism was ascribed to the photo-induced electron transfer (PET) and protonation, which were verified by 1H NMR spectra and theoretical calculations. [ABSTRACT FROM AUTHOR]

By adding different proportions of N-butylimidazole and carboxyethylthiosuccinic acid (CETSA), three hybrid systems of ionic liquids were synthesized and named ILHS1, ILHS2 and ILHS3. Using the weight loss method, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and contact angle test, it was determined that ILHS2 had the best corrosion inhibition among the three ionic liquid systems, and that the inhibition efficiency reached up to 90.63% when the concentration was 10 mM in 1 M HCl at 308 K. The adsorption isotherm was consistent with Langmuir adsorption, and combined with molecular dynamics simulation (MD), it was proved that mixed adsorption occurred on the metal interface. Polarization curves showed that the ionic liquid mixture systems could inhibit the corrosion of both poles, meaning that the anions and cations could act synergistically, and that the anions played a major role. The elemental and molecular structures of ILHS1, ILHS2 and ILHS3 were investigated using 1H NMR, which indicated that the three carboxyl groups on CETSA were regionally selective and combined with imidazole cations to form ionic liquid mixture systems. [ABSTRACT FROM AUTHOR]

Two 2,7-disubstituted spiro[fluorene-9,9′-xanthene] derivatives, 2,7-bis(4-(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl)spiro[fluorene-9,9′-xanthene] (SFX-2BI) and 2,7-bis(4-(1-(4-(tert-butyl)phenyl)-4,5-diphenyl-1H-imidazol-2-yl)phenyl)spiro[fluorene-9,9′-xanthene] (SFX-2IM), were synthesized by grafting imidazole-derived moieties with different electron-withdrawing abilities onto the 2- and 7-positions of a spiro[fluorene-9,9′-xanthene] (SFX) core. Their photophysical and electrochemical properties, thermal stability and electroluminescent properties were investigated. The results showed that these compounds have excellent thermal stability and exhibit strong deep-blue emission in dichloromethane solution. In addition, the vacuum-processed doped and non-doped devices based on SFX-2BI and SFX-2IM were fabricated, in which the device prepared using SFX-2BI as the emitting material exhibited the best device performance with a turn-on voltage of 5.5 V, a maximum brightness of 3984 cd m−2, a maximum current efficiency of 3.65 cd A−1 and a maximum external quantum efficiency of 2.61%. [ABSTRACT FROM AUTHOR]

Two cross-linkable iridium(III) complexes, Ir(L)2(acac) and Ir(L)2(Stpip), where L = 1-phenyl-2-(4′-vinyl-[1,1′-biphenyl]-4-yl)-1H-benzo[d]imidazole, acac = acetylacetonate, and Stpip = bis(diphenylphorothioyl)amide, were synthesized and characterized by elemental analysis, NMR (1H and 13C) spectroscopy and HRMS. The iridium(III) complexes exhibited excellent thermal stability and green–yellow emission with a maximum main peak at 563 nm. The photoluminescence quantum yields of Ir(L)2(acac) and Ir(L)2(Stpip) were 2.77% and 1.80%, respectively, in CH2Cl2 solution. The vacuum-processed electroluminescence device fabricated from Ir(L)2(acac) at 4 wt% doping concentration exhibited a maximum current efficiency (CEmax) of 26.3 cd A−1, a maximum brightness of 9645 cd m−2 and a maximum external quantum efficiency (EQEmax) of 14.7%. The solution-processed electroluminescence device based on Ir(L)2(acac) exhibited a maximum current efficiency (CEmax) of 3.71 cd A−1, a maximum brightness of 2237 cd m−2 and a maximum external quantum efficiency (EQEmax) of 1.36%. [ABSTRACT FROM AUTHOR]

Considering the coordination advantage of N-heterocyclic carboxylate ligands in the construction of metal–organic frameworks (MOFs), we hope to adopt them to build up more structurally stable MOFs for proton conduction research. Therefore, the multifunctional ligand of 2-(2-carboxyphenyl)-4,5-imidazole dicarboxylic acid (o-CPH4IDC) was selected by us. Consequently, two highly water-stable Ba(II) and Cd(II) MOFs, {[Cd(o-CPH2IDC)(4,4′-bipy)0.5(H2O)2]·3H2O}n (1) (4,4′-bipy = 4,4′-bipyridine) and [Ba(o-CPH2IDC)]n (2) were made. The further study of water-assisted proton conduction for 1 and 2 demonstrated that both were temperature- and humidity-dependent proton conductors, and their best proton conductivities could reach 10−4 S·cm−1 at 100 °C and 98% RH. The vehicle mechanism can be proposed for 1 and 2 by calculating the activation energy and by analysing their crystal structures. Apparently, the adsorbed water molecules and carboxylate groups in the MOFs played an important role in the proton conduction process. Our work gives more choice for the design of novel proton conductive MOF materials. [ABSTRACT FROM AUTHOR]

With increasing industrial development, heavy metal ions have been widely released, and fluorescence detection is an effective approach owing to its high selectivity and sensitivity. Herein, a water-soluble luminescent sensor based on a spirobifluorene-based imidazolium polymer (IMSPF-Br-COOH) is developed from tetraimidazole spirobifluorene and 3-bromo-2-bromomethylpropionic acid through a quaternization reaction. IMSPF-Br-COOH has an imidazolium cationic network and carboxyl coordination groups. Consequently, fluorescence quenching of IMSPF-Br-COOH exhibits high selectivity for Fe3+ and Cr2O72−via coordination and anion exchange. The corresponding quenching coefficient (Ksv) is 2.0772 × 103 L mol−1 for Fe3+ and 1.0081 × 104 L mol−1 for Cr2O72−. The detection limit (LOD) is calculated to be 170.56 μmol L−1 for Fe3+ and 100.81 μmol L−1 for Cr2O72−. This work provides a novel approach for metal ion detection by water-soluble polymers. [ABSTRACT FROM AUTHOR]

Laser ignition of explosives is believed to be a safe and reliable initiation method to trigger the reaction of energetic materials. Energetic complexes including most primary explosives are a class of important explosives. The determinant of the laser initiation threshold of energetic complexes is still unclear. The coordination metal ions have a significant influence on the properties of energetic complexes. However, the effect of metal ions on the laser ignition ability has not attracted enough attention. To inspect the influence of alkali and alkaline earth metal ions on the laser initiation ability of energetic complexes, sodium(I) (1), potassium(I) (2), magnesium(II) (3), calcium(II) (4), and barium(II) (5) containing energetic complexes based on the ligand 4,4′,5,5′-tetranitro-2,2′-biimidazole (TNBI) were prepared. The crystal structures and thermal behaviors of four new complexes (1, 3, 4, and 5) were characterized. Laser initiation tests were carried out using different laser energy densities. TNBI and all complexes could be initiated and they all exhibited deflagration processes. It is found that the initiation delay times have a definite relationship with the metal ion type. Two alkali metal-containing complexes were easy to initiate, followed by the ligand TNBI, whereas the alkaline earth metal-containing complexes showed longer initiation delay times. [ABSTRACT FROM AUTHOR]

An amazing and stable carbonized octahedral frame material Cu-PC@OFM was synthesized and characterized through HRTEM, SEM, XRD, XPS, and Raman spectroscopy and nitrogen adsorption/desorption analysis. In particular, the carbon matrix carrier loaded with nano-copper not only maintains the original structure, but also the nano copper particles generated in situ significantly improve the catalytic performance and stability. It was disclosed that the copper-based catalyst material Cu-PC@OFM showed high catalytic activity in the borrowing hydrogen reaction and the synthesis of 1-benzyl-2-aryl-1H-benzo[d]imidazole derivatives with high yields in water. This copper catalytic system provided a much greener and efficient catalyst for the synthesis of functionalized amines and 1-benzyl-2-aryl-1H-benzo[d]imidazoles with good recovery performance in water, which was the first example for the Cu-PC@OFM material-catalyzed synthesis of 1-benzyl-2-aryl-1H-benzo[d]imidazoles. In addition, a plausible reaction mechanism was proposed through some condition control experiments, deuterium labeling experiments and separation of intermediates experiments. [ABSTRACT FROM AUTHOR]

Eight Cu(II) coordination compounds with cyclic triimidazole, triimidazo[1,2-a:1′,2′-c:1′′,2′′-e][1,3,5]-triazine (L1), its positional isomer, triimidazo[1,2-a:1′,2′-c:1′′,5′′-e][1,3,5]-triazine (L2), and two pyridine derivatives of L1, 3-(pyridin-2-yl)triimidazo[1,2-a:1′,2′-c:1′′,2′′-e][1,3,5]triazine (L3) and 3-(pyridin-4-yl)triimidazo[1,2-a:1′,2′-c:1′′,2′′-e][1,3,5]triazine (L4) are reported. All compounds represent neutral Cu(II) discrete complexes or coordination polymers comprising luminophore triimidazole molecules and charge-compensated anions. Starting from copper(II) acetate monohydrate with the paddle-wheel geometry, two binuclear complexes [Cu2(CH3COO)4(L1)2] (1) and [Cu2(CH3COO)4(L3)2] (2), a mixed-dimensional 0D/1D coordination compound {[Cu2(CH3COO)4(L2)]2[Cu2(CH3COO)4(H2O)(L2)]·2(H2O)}n (3), all with binuclear paddle-wheel [Cu2(CO2)4] secondary building units, and a mononuclear complex [Cu(CH3COO)2(L2)2] (4) with square-planar N2O2 Cu(II) coordination, were obtained. Starting from copper(II) nitrate trihydrate, three mononuclear complexes [Cu(NO3)2(L2)4]·2CH3CN (5), [Cu(NO3)2(L2)4]·1.5(dmf) (6), and [Cu(NO3)2(H2O)2(L4)2]·2H2O (7) with Cu(II) distorted octahedral N4O2 and N2O4 coordination cores, and 1D coordination polymer [Cu(NO3)2(L3)]n (8) with the distorted square pyramidal N2O3 Cu(II) coordination geometry were obtained. In the mono- and binuclear complexes, luminophores L1–L4 coordinate as monodentate terminal ligands. In the coordination chain 3 the L2 ligand acts as a bidentate-bridging exo-ligand, while in 8 the L3 ligand acts as a bidentate-chelate one, and the structure extension to 1D is achieved via the bridging nitrate-anions. The compromise between the hydrogen bonds and π⋯π stacking interactions defines the stacking patterns of bulky luminophores coordinated to the metal center that vary from the dimeric associates to the infinite 2D motifs with the different overlapping areas of the stacking ligands. The strong aggregation-induced emission demonstrated by pure luminophores was nearly quenched in the reported Cu(II) coordination compounds in the solid state. [ABSTRACT FROM AUTHOR]

A new intramolecular charge transfer (ICT) based fluorescent turn-on ratiometric probe 2(D–π–A type) has been designed and synthesized by bridging imidazole (donor, D) and benzothiazole (acceptor, A) moieties through a phenyl ring. The photophysical behavior of probe 2in solvents of different polarities and at different pH values has been investigated. Upon interaction with different types of anions probe 2showed selective high affinity for fluoride anions (F−) in aqueous DMSO (20%) solution. The ratiometric fluorescence turn-on behavior displayed by 2with F−is attributed to changes in the ICT process. Job's plot analysis revealed a 1 : 1 binding stoichiometry for 2+ F−interactions with a high binding constant and detection sensitivity (30 ppb). Moreover, a solution of 2+ F−enabled the detection of CO2(∼100 ppb; 2.29 μM) through enhanced emission. The mode of interaction has been confirmed by 1H NMR titration studies which suggested the deprotonation of the –NH fragment of an imidazolyl unit in the presence of F−. [ABSTRACT FROM AUTHOR]

Luminescent materials with aggregation-induced emission enhancement (AIEE) have received increasing attention as chemosensors. Four AIEE active imidazole derivatives with TPA moieties, M-MAP, M01-DMAC, M-IF, and M01-IF, have been developed for the sensitive detection of NAC explosives. The luminescence behaviors of compounds were systematically measured. In 90% THF/H2O, 100–200 nm aggregated nanoparticles were formed with good regularity and stability. The intramolecular free rotations were restricted and emissions were enhanced within the aggregated state. The fluorescence of aqueous AIEE dispersions showed sensitive quenching by picric acid (PA), and the LOD was determined to be 30.99 nM for M-MAP. The intermolecular PIET mechanism was responsible for recognition and sensitive detection. Moreover, their AIEE luminescence behaviors respond weakly to other nitroaromatic compounds (NACs) or analogs. The quenching efficiencies, for M-MAP and M01-MAP, were almost consistent with the risk degrees of NACs. The test strips were easily prepared and the emission quenching effect was simply observed after contacting NACs. The potential of our new AIEEs was demonstrated for the fabrication of convenient and easily operating sensors for NACs. [ABSTRACT FROM AUTHOR]

One-pot synthesis of POM-salt ([Himi]4[SiMo12O40] (1)) was achieved by mixing silicomolybdic acid and imidazole in acidic conditions and characterized by FTIR, TGA, SEM, EDX, ICP-OES and XPS. The structure of 1 was confirmed by single crystal X-ray analysis. The matching of the simulated PXRD pattern with the experimental pattern indicates the phase purity of 1. Interestingly, 1 showed highly selective and sensitive colorimetric detection of hydrated zinc chloride (ZnCl2·2H2O). The addition of ZnCl2·2H2O into 1 in the DMSO–H2O mixture shows the formation of blue colour. Furthermore, metal ions including other anionic zinc salts did not produce any colour change. The limit of detection was calculated to be 0.15 μM. Similarly, solid mixing of ZnCl2·2H2O with 1 can also produce a visible blue colour change. On the other hand, anhydrous ZnCl2 did not form any color change under the same conditions. The mechanistic studies indicate that the reduction of Mo6+ to Mo5+ might be responsible for the selective colour change. The reversible colour change between colorless and blue colour upon addition of EDTA into 1-ZnCl2·2H2O demonstrates the reusability of 1. Furthermore, microbial activity of 1 was investigated towards a series of Gram-positive and Gram-negative bacterial and fungal strains. Effective bactericidal activity of 1 was analyzed against Staphylococcus aureus. [ABSTRACT FROM AUTHOR]