A new colorimetric and fluorescent chemosensor based on thiacalix[4]arene for fluoride ions

Perylene tetra-(alkoxycarbonyl) derivative and its copper chelate for selective sensing of fluoride ions

Two novel fluoride ion fluorescent probes (P1 and P2) containing perylene tetra-(alkoxycarbonyl) derivative (PTAC) and its copper chelate were designed and synthesized. The identification properties of the probes were studied by absorption and fluorescence methods. The results showed that the probes were highly selective and sensitive to fluoride ions. ¹H NMR titration confirmed that the sensing mechanism involved the formation of H-bond between the O-H moiety and fluoride ions, and the coordination of copper ion could enhance the H-bond donor capacity of the receptor unit (O-H). The corresponding orbital electron distributions were calculated by density functional theory (DFT). In addition, fluoride ion can be easily detected by probe-coated Whatman filter paper without the need for expensive equipment. Until now, there have been few reports of such probes enhancing the capacity of the H-bond donor based on metal ion chelation. This study will contribute to the design and synthesis of novel sensitive perylene fluoride probes.

CTV Based Sensor for the Rapid Detection of Nitro Toluene With Computational Studies and Molecular Modelling

A new tri-naphthoylated Cyclotriveratrylene molecule has been synthesized for the rapid and sensitive detection of 4-nitrotoluene (4-NT) among various nitro aromatic compounds (NACs) by using a spectrofluorimetric method. The newly derrivatized cyclotriveratrylene compound is successfully confirmed by using the available techniques of ¹H-NMR, ¹³CNMR, and ESI-MS. This synthesised molecule is 1NC-CTV (1-Naptholy Chloride-Cyclotriveratrylene). Strong quenching in the fluorescence intensity of 1NC-CTV was observed upon the addition of 4-NT. Further quantum yield studies were carried out and by using the stern volmer it was concluded that the fluorescence quenching mechanism is dynamic or static. The molecule 1NC-CTV was further studied with the help of computational methods such as molecular docking to study the binding interactions and properties of the molecule.

Development of tBu-phenyl Acetamide Appended Thiacalix[4]arene as "Turn-ON" Fluorescent Probe for Selective Recognition of Hg(II) Ions

Herein, a novel N-(4-(tert-butyl)-phenyl)-2-chloroacetamide functionalized thiacalix[4]arene architecture, viz TCAN2PA has been synthesized and the sensing behaviour towards metal ions were explored. The probe, TCAN2PA displayed "turn-on" fluorescence response towards Hg(II) ions in acetonitrile over a series of competing common metal ions. A bathochromic shift in absorption band along with a significant "Turn-On" fluorescence behaviour of TCAN2PA was observed upon interaction with Hg(II) ions. The lower rim modification of thiacalixarene with N-(4-(tert-butyl)-phenyl)-2-chloroacetamide actively contributes toward the fluorescence property due to the presence of strong electron-donating aryl amido substituent. Fluorescence titration experiments were conducted to find out the limit of detection and to understand binding stoichiometry as well. The electron transfer interactions between the electron rich TCAN2PA host with Hg(II) ions have been postulated which is also supported by computational modelling insights.

Triazole derived azo-azomethine dye as a new colorimetric anion chemosensor

In the pursue of developing anion sensors, an efficient triazole derived azo-azomethine dye chemosensor (S) that differentially senses F‾ and AcO‾ ions has been reported. The ions recognition ability of S was investigated by colorimetric and UV-visible spectroscopic methods. Interestingly, this chemosensor molecule is virtually inactive in presence of other anions such as Cl‾, Br‾ and I‾ and HSO₄‾. We have further presented a ratiometric approach to differentiate F‾ and AcO‾ ions. The reversibility of F‾ ion binding with S was established by the addition of Ca(NO₃)₂ to the fluoride bound S, which led to the regeneration of S. The quantum chemical calculation of energies of unbound and bound S has been employed using Density Functional Theory (DFT) to understand the interaction between chemosensor and anions. Evidence in support of fluoride-induced deprotonation of a O-H bond during the detection of F⁻ ion has been demonstrated by employing ¹H NMR titration experiments.

Luminescent behavior of pyrene-allied calix[4]arene for the highly pH-selective recognition and determination of Zn2+, Hg2+ and I−via the CHEF-PET mechanism: computational experiment and paper-based device

In this article, for the first time, we have reported a novel CHEF-PET fluorescence sensor L based on calix[4]arene containing four pyrene groups as binding sites, which is highly selective and sensitive towards Zn²⁺, Hg²⁺ and I⁻.

A Cr(VI) selective probe based on a quinoline-amide calix[4]arene

A new quinoline-amide calix[4]arene 3-receptor for detection of hazardous anions and cations have been synthesized. The 3-receptor was examined for its sensing properties towards several different anions (Cr₂O₇^2-, SCN^-, F^-, Cl^-, NO₃^-) and metal ions (Hg²⁺, Cd²⁺, Ag⁺) by UV-vis and fluorescence spectroscopies. It was detected that the 3-receptor has only sensing ability for Cr₂O₇^2- and Hg²⁺ ions, resulting in the association constants higher for Cr₂O₇^2- than to the Hg²⁺ ions. High selectivity towards Cr₂O₇^2- were also observed by fluorescence measurement among other ions (F^-, Cl^-_, SCN^-, Hg²⁺, Cd²⁺, Ag⁺) with a low limit of detection (7.36×10^-6moldm^-3). Proton NMR anion-binding investigations revealed a strong interaction of Cr₂O₇^2- anion with NH and CH groups of the receptor, showing that the combination with hydrogen-bonds donor groups strengthened the anion receptor association. Furthermore, remarkable association constants for dichromate anion obtained by all techniques strongly suggest the 3-receptor as a selective Cr(VI) sensor.

Sensing of Ce(iii) using di-naphthoylated oxacalix[4]arene via realistic simulations and experimental studies

Here, we report a fluorescent sensor for the detection of Ce(iii) using di-naphthoylated oxacalix[4]arene (DNOC).

Dual in vitro and in silico analysis of thiacalix[4]arene dinaphthalene sulfonate for the sensing of 4-nitrotoluene and 2,3-dinitrotoluene

A newly synthesized thiacalix[4]arene dinaphthalene sulfonate, i.e., TCDNS, has been used as a fluorescence quencher for 2,3-DNT as well as 4-NT. The complex was analyzed by ESI-MS and ¹H-NMR titration, which has been further confirmed by the in silico study.

A turn-off fluorescence sensor for insensitive munition using anthraquinone-appended oxacalix[4]arene and its computational studies

Herein, a fluorescent oxacalix[4]arene-based receptor, DAQTNOC(5,17-di(N-(9,10-dioxo-9,10-dihydroanthracen-1-yl)acetamide) tetranitrooxacalix[4]arene), was described for the specific recognition of N-methyl-p-nitroaniline (MNA).

Synthesis, crystal structure and remote allosteric binding properties of cone thiacalix[4]pseudocrown receptors bearing anthraquinone function and different arms

Herein, three novel cone thiacalix[4]pseudocrown receptors 1–3, bearing anthraquinone and triazole functions as well as different side arms, were successfully synthesized via a double click reaction as the key step.