Oligopyrrole macrocycles: receptors and chemosensors for potentially hazardous materials

Oligopyrroles represent a diverse class of molecular receptors that have been utilized in a growing number of applications. Recently, these systems have attracted interest as receptors and chemosensors for hazardous materials, including harmful anionic species, high-valent actinide cations, and nitroaromatic explosives. These versatile molecular receptors have been used to develop rudimentary colorimetric and fluorimetric assays for hazardous materials.     

An indirect approach for anion detection: the displacement strategy and its application

The development of new optical anion chemosensors with high sensitivity and selectivity is very important, since anions possess some fundamental roles in a wide range of biological and chemical processes. The displacement approach is a method using anion binding sites and signaling subunits, which are not covalently attached but forming a coordination complex, in which the presence of anions revives the noncoordinated spectroscopic behavior of the indicator. In the past five years, according to the displacement strategy, many good optical anion chemosensors have been successfully obtained. This paper reviews the recent progress in the field of the fluorescent and colorimetric anion chemosensors designed according to the displacement strategy (mainly from 2008 to 2011), and gives some outlooks for the further exploration of new optical anion chemosensors.     

Fluorescent “Turn‐on” Sensing Based on Metal–Organic Frameworks (MOFs)

Metal–organic frameworks (MOFs) have evolved as an exciting class of materials in the domain of porous materials. The unique features of these materials arise from the combined properties of metal ions/clusters and organic struts which form the building blocks of these fascinating architectures. Among other multifarious applications, MOFs have shown tremendous applications as sensory materials for a wide variety of species. The signal transduction induced mechanism in these confined nanospaces generate optical output in response to a particular analyte which can be detected by wide variety of detection techniques. Fluorometric methods of sensing is one of widely studied method over past few decades. MOF‐based fluorometric detection is a key research theme developed over the past few years. In this review, we give a brief overview of the recent developments of MOFs as “turn‐on” sensors for a wide range of analytes (viz. cations, anions, volatile organic compounds (VOCs), etc.).     

铱配合物在磷光化学传感器中的应用

由于在生物领域和物联网领域的广泛应用,化学传感器在近期发展迅速.相比于纯有机分子的荧光化学传感器,基于重金属配合物的磷光化学传感器由于发光寿命长,斯托克斯位移大等优点越来越引起人们的广泛关注.重金属铱配合物三线态寿命短,发光效率高而且配合物的发射波长容易受配体的改变而发生变化,因此成为最好的磷光传感器材料之一.本文介绍了铱配合物在磷光化学传感器领域中的应用,具体包括:阳离子传感器、阴离子传感器、氧分子传感器、氨基酸传感器、pH传感器等,并指出了相比于其它磷光化学传感器,基于铱配合物的磷光化学传感器的优势以及目前所存在的问题,最后,对基于铱配合物的磷光化学传感器的研究和发展方向进行了展望.     

Recent progress in fluorescent and colorimetric chemosensors for detection of precious metal ions (silver, gold and platinum ions)

Due to the wide range of applications and biological significance, the development of optical probes for silver, gold and platinum ions has been an active research area in the past few years. This tutorial review focuses on the recent contributions concerning the fluorescent or colorimetric sensors for these metal ions, and is organized according to their structural classifications (for Ag(+) detection) and unique mechanisms between the sensors and metal ions (for Au(3+) and Pt(2+) detection).     

可用于连续识别Cu^2+和阴离子、中性分子荧光探针的研究进展

铜(Cu)含量的高低直接影响着生命体的正常运转和自然体系的平衡.检测铜离子的方法多种多样,其中具有较高敏感度和选择性的荧光化学传感器应用更加广泛.综述了以Cu^2+为基的荧光化学传感器通过"替换"法实现了对阴离子S^2-, CN^-, H2PO4^-, PPi和I^-以及中性分子ATP、ADP和生物硫醇等的连续识别的研究进展.     

Materials‐Based Receptors: Design Principle and Applications

This review focuses on recent developments and growth potential in colorimetric and/or fluorimetric chemosensors based on rationally designed materials and suitable for use in highly selective and sensitive naked‐eye detection of environmental and biological analytes.     

Functionalized magnetic nanoparticles as chemosensors and adsorbents for toxic metal ions in environmental and biological fields

Functionalized magnetic nanoparticles, composed of both inorganic and organic components, have recently been examined as promising platforms for detection and separation applications. This unique class of nanomaterials can retain not only beneficial features of both the inorganic and organic components, but can also provide the ability to systematically tune the properties of the hybrid materials through the combination of appropriate functional components. This tutorial review focuses on the recent development of functionalized magnetic nanoparticles for use in biological and environmental applications, in which these chromogenic and fluorogenic chemosensors can selectively detect and separate specific toxic metal ions.     

Synthesis and evaluation of benzothiazolyl and benzimidazolyl asparagines as amino acid based selective fluorimetric chemosensors for Cu

A series of emissive N-tert-butyloxycarbonyl benzyl ester asparagines bearing benzothiazole and benzimidazole units at the side chain, functionalised with electron donor or acceptor groups, were evaluated as novel amino acid based fluorimetric chemosensors for transition metal cations, such as Cu²⁺, Zn²⁺, Co²⁺ and Ni²⁺. Selective removal of the protecting groups at the N- and C-terminals was carried out in order to assess the influence of the presence of blocking groups on the overall coordination ability. The results indicate that there is a strong interaction through the donor N, O and S atoms at the side chain of the various asparagines, with high selectivity towards Cu²⁺ in a 1:1 complex stoichiometry. Association constants and detection limits for Cu²⁺ were calculated. The photophysical and metal ion sensing properties of these asparagines suggest that they can be suitable for incorporation into peptidic chemosensor frameworks.     

Nucleobase-containing transition metal complexes as building blocks for biological markers and supramolecular structures

The incorporation of metal complexes into nucleobases, nucleosides and nucleotides has provided a focus for the development of many novel compounds with a wide range of applications. In this perspective article the different methods to incorporate transition metal complexes into these species will be described. Applications of these compounds as biological markers, catalysts and how the hydrogen bonding properties may be employed in directing supramolecular assembly in both the solid state and solution will be discussed.     

Trace metal recovery and concentration using ferrites

Ferrites have been used to separate a wide range of substances such as dissolved metal species, particulate matter, and organic and biological materials; they have been used almost exclusively for metal waste treatment applications. However, ferrites can be used to remove and concentrate selected trace metals in a wide variety of feed solutions requiring analysis. A brief overview of ferrite properties and recent applications for trace metal recovery and concentration will be presented.     

Laser-induced Fourier transform ion cyclotron resonance mass spectrometry of organic and inorganic compounds: methodologies and applications

The combination of a laser with a Fourier transform ion cyclotron resonance mass spectrometer (FTICRMS) enables a variety of MS experiments to be conducted. The laser can be used either as an intense photonic source for the photoionization of neutral species introduced in a variety of ways into the FTICR cell, or it can be made to directly interact with a solid, generating gas-phase ions. Depending on the experimental conditions used, various laser-matter interactions can occur. When high laser energy (also referred to as power density or irradiance) is used, laser ablation (LA) processes lead to the release of species into the gas phase, a significant fraction of which are ionic. The number of ions decreases with the irradiance. For low irradiance values, the so-called laser desorption (LD) regime applies, where the expelled species are mainly neutrals. LA–FTICRMS and LD–FTICRMS can be used to study a wide range of materials, including mineral, organic, hybrid and biological compounds (although matrix-assisted laser desorption ionization, MALDI, which is not reviewed in this paper, is more commonly applied to biological compounds). This paper will review a selection of methodological developments and applications in the field of laser ionization FTICRMS, LD–FTICRMS, and LA–FTICRMS for the analysis of organics and inorganics in complex mixtures, emphasizing insoluble materials. Specifically, silicate- and carbon-based complex materials as well as organic compounds will be examined due to their relevance to natural environmental and anthropogenic matrices.     

Synthetic Strategies for Fused Benzothiazoles: Past,Present, and Future

Benzothiazole is used as a building block in organic synthesis, which serves as a key template for the development of various therapeutic agents and shows a wide spectrum of activities. The attractive application of benzothiazole in organic synthesis is undoubtedly due to the highly reactive C-2 amino group, which is responsible for the change in its bioactivity. The construction of a poly-heterocyclic compound with the fused hetero-systems has attracted increasing attention because of the diverse range of potential therapeutic activities. Significant efforts have been undertaken to exploit different synthetic routes to these compounds. This article gives a comprehensive account of the synthetic utility of benzothiazole employed in the design and synthesis of different types of compounds containing fused heterocyclic rings with greater emphasis on recent literature.     

Squaraine-based colorimetric and fluorescent sensors for Cu-specific detection and fluorescence imaging in living cells

New squaraine-based chemosensors SQ1 and SQ2 functionalized with 2-picolyl units were first synthesized and used as highly selective and sensitive colorimetric and fluorometric dual-channel sensors for Cu²⁺-specific recognition in aqueous systems. Among a series of individual metal ions, only Cu²⁺ could result in dramatic color changes. We also evaluated their capability of biological applications and found that SQ2 could be successfully employed as a Cu²⁺-selective probe in the fluorescence imaging of living cells.     

Acridino-Diaza-20-Crown-6 Ethers: New Macrocyclic Hosts for Optochemical Metal Ion Sensing

Acridino-diaza-20-crown-6 ether derivatives as new turn-on type fluorescent chemosensors with an excellent functionality and photophysical properties have been designed and synthesized for metal ion-selective optochemical sensing applications. Spectroscopic studies revealed that in an acetonitrile-based semi-aqueous medium, the sensor molecules exhibited a remarkable fluorescence enhancement with high sensitivity only toward Zn²⁺, Al³⁺ and Bi³⁺, among 23 different metal ions. Studies on complexation showed a great coordinating ability of logK > 4.7 with a 1:1 complex stoichiometry in each case. The detection limits were found to be from 59 nM to micromoles. The new ionophores enabled an optical response without being affected either by the pH in the range of 5.5–7.5, or the presence of various anions or competing metal ions. Varying the N-substituents of the new host-backbone provides diverse opportunities in both immobilization and practical applications without influencing the molecular recognition abilities.     

Using ratiometric indicator-displacement assays in semi-quantitative colorimetric determination of chloride, bromide, and iodide anions

A ratiometric indicator-displacement assay (RIDA) array has been developed for the semi-quantitative colorimetric determination of chloride, bromide, and iodide anions. Determinations of these halide anions follow the displacement reaction using the chelate compound of (2-(3,5-dibromo-2-pyridylazo)-5-(diethylamino)phenol) (3,5-Br2-PADAP) and heavy metal salts as colorimetric reagent. Different from regular silver nitrate titrations, the chloride, bromide, and iodide anions compete with the 3,5-Br2-PADAP ligand and change the colour of the 3,5-Br2-PADAP-metal chelate compound dramatically. These clearer colour changes make the semi-quantitative colorimetric determination of chloride, bromide, and iodide anions possible. The colour changes are imaged using a conventional flatbed scanner, and digitized. After statistical analysis, these colour changes in the RIDA array provide facile identification of chloride, bromide, and iodide anions at a wide concentration range (10 μM to 10 mM) without any misclassification. The RIDA array is able to discriminate without misclassifications among seven concentrations of chloride, bromide, and iodide anions. No shelf life issue exists because the chelating compounds react with halide anions directly without any pre-immobilizations.     

识别过渡金属离子的1,8-萘二甲酰亚胺多胺衍生物荧光传感器的研究

A series of fluorescent chemosensors 1-3 were synthesized to detect transition metal ions. At the room temperature, fluorescence intensities of these chemosensors in acetonitrile without transition metal ions were found to be very weak, due to the process of the e±cient intramolecular photoinduced electron transfer (PET). However, after addition of the transition metal ions, the chemosensor 1-3 exhibits obvious fluorescence enhancement. Moreover, the intensity of the fluorescence emission of chemosensors increases significantly in the presence of Zn2+ and Cd2+. The fluorescent chemosensors with different polyamine as receptors show diverse a±nity abilities to the transition metal ions and signal the receptor-metal ion interaction by the intensity change of fluorescence emission.     

Optical colorimetric sensor arrays for chemical and biological analysis

In recent years, the sensor array has attracted much attention in the field of complex system analysis on the basis of its good selectivity and easy operation. Many optical colorimetric sensor arrays are designed to analyze multi-target analytes due to the good sensitivity of optical signal. In this review, we introduce the targeting analytes, sensing mechanisms and data processing methods of the optical colorimetric sensor array based on optical probes (including organic molecular probes, polymer materials and nanomaterials). The research progress in the detection of metal ions, anions, toxic gases, organic compounds, biomolecules and living organisms (such as DNA, amino acids, proteins, microbes and cells) and actual sample mixtures are summarized here. The review illustrates the types, application advantages and development prospects of the optical colorimetric sensor array to help broad readers to understand the research progress in the application of chemical sensor array.     

Surface modification of natural cellulose substances:toward functional materials and applications

Combining various synthetic chemical processes and biological assemblies provides a promising strategy for the design and fabrication of functional materials with tailored structures and properties.The unique multilevel structures and morphologies of natural cellulose substances such as ordinary commercial laboratory filter paper make them ideal platforms for the self-assemblies of various functional guest molecules that are to be deposited on the surfaces of their fine structures,and the resulting composite matters show significant potentials for various applications.The surface sol-gel process was employed to deposit ultrathin metal-oxide(e.g.,titania and zirconia)gel films to coat the cellulose nanofibers in bulk filter papers;thereafter,monolayers of specific guest substrates were immobilized onto the surfaces of the metal-oxide gel films.Highly selective,sensitive,and reversible chemosensors based on the surface modification of filter paper were obtained toward the fluorescence and colorimetric detection of various analytes such as heavy-metal ions,inorganic anions,amino acids,and gases.Cellulosebased composite materials with superhydrophobic,antibacterial,or luminescent properties were fabricated by self-assembly approaches toward practical applications.     

Formation of peptide radical ions through dissociative electron transfer in ternary metal-ligand-peptide complexes

The formation and fragmentation of odd-electron ions of peptides and proteins is of interest to applications in biological mass spectrometry. Gas-phase redox chemistry occurring during collision-induced dissociation of ternary metal-ligand-peptide complexes enables the formation of a variety of peptide radicals, including the canonical radical cations, M(+?), radical dications, [M+H](2+?), radical anions, [M-2H](-?) and phosphorylated radical cations. In addition, odd-electron peptide ions with well-defined initial location of the radical site are produced through side-chain losses from the radical ions. Subsequent fragmentation of these species provides information regarding the role of charge and location of the radical site on the competition between radical-induced and proton-driven fragmentation of odd-electron peptide ions. This account summarizes current understanding of the factors that control the efficiency of the intramolecular electron transfer (ET) in ternary metal-ligand-peptide complexes resulting in formation of odd-electron peptide ions. Specifically, we discuss the effect of the metal center, the ligand and the peptide structure on the competition between the ET, proton transfer (PT) and loss of neutral peptide and neutral peptide fragments from the complex. Fundamental studies of the structures, stabilities and the energetics and dynamics of fragmentation of these complexes are also important for detailed molecular-level understanding of photosynthesis and respiration in biological systems.