Anion Recognition Research Articles

Crystal structure, characterization and chemical reactivity of novel piperazine derivative ligand for electrochemical recognition of nitrite anion

Abstract: A novel piperazine derivative (3E,3′E)-3,3′-(((piperazine-1,4-diyl bis (ethane-2,1-diyl)) bis (azanediyl)) bis (ethan1-yl-1-ylidene)) bis (6-methyl-2H-pyran-2,4(3H)-dione) (2E-Peaemp) has been synthesized and characterized by ESI-MS, Single-crystal X-ray diffraction, NMR (1H NMR, 13C NMR and 2D NMR), ATR-FTIR, UV-Visible and SEM. The theoretical study of chemical reactivity of 2E-Peaemp was investigated using DFT method. The oxidation-reduction processes and interaction between 2E-Peaemp and nitrite ions were studied using cyclic voltammetry technique. In addition, the detection of NO2− was investigated in 0.1 M PBS solution (pH = 7.0) using a carbon paste electrode modified with reduced graphene oxide-graphite carbon/2E-Peaemp system (rGO-GC/2E-Peaemp). XRD study showed that 2E-Peaemp crystallizes in a monoclinic system with P21/c space group, and the results obtained from theoretical study well support the experimental results. According to DFT study, HOMO (Highest Occupied Molecular Orbitals)-LUMO (Lowest Unoccupied Molecular Orbitals) energy gap (Egap) and other reactivity descriptors were calculated. The results showed that the ligand exhibits a high chemical reactivity and low kinetic stability. Finally, the cyclic voltammetry measurements showed significant current responses of rGO-GC/2E-Peaemp electrode towards NO2− in the concentration range of 0–4 mM with a low limit of detection (LOD = 0.83 μM). Graphic abstract: New ligand (2E-Peaemp: (3E,3′E)-3,3′-(((piperazine-1,4-diyl bis (ethane-2,1-diyl)) bis (azanediyl)) bis (ethan1-yl-1-ylidene)) bis (6-methyl-2H-pyran-2,4(3H)-dione)) has been synthesized and characterized by XRD technique. The reactivity descriptors have been calculated by DFT. The ligand was used for electrochemical recognition of nitrite anion. The cyclic voltammetry showed that the modified electrode with 2E-Peaemp exhibits low detection limit towards NO2−.[Figure not available: see fulltext.] © 2021, Indian Academy of Sciences.

A Visual and Ratiometric Chemosensor Using Thiophene Functionalized Hydrazone for the Selective Sensing of Pb2+ and F- Ions.

Herein, a simple, efficient ratiometric chemosensor was reported for the selective sensing of Pb2+ and F- ions using thiophene functionalized hydrazone as a chemical probe. Hydrazone moiety was developed by utilizing thiophene/naphthalene as a platform for the particular recognition of cation and anion. The structures of the precursor (Z)-(1-(5-bromothiophen-2-yl)ethylidene)hydrazine (ABTH) and the final probe 1-((Z)-(((Z)-1-(5-bromothiophen-2-yl)ethylidene)hydrazono)methyl)naphthalen-2-ol (NAPABTH) were confirmed by 1H, 13C-NMR and LC-MS spectroscopic methods. The interaction of NAPABTH with Pb2+ and F- ions was visually observed by the formation of pink and dark yellow solutions, respectively. The detection limits were found to be very low for Pb2+ as 1.06ppm and for F- ions as 3.72nM. This visual detection of Pb2+/F- ions with satisfactory outcomes obtained from UV-Vis titrations. The sensing mechanistic pathways and stoichiometric ratios were obtained from DFT and Job's plot, respectively. The observed results are highly promising as highly selective chemosensor with lower detection limits for Pb2+ and F- ions. This strategy could exhibit tremendous applications for the selective sensing of heavy metal cations with rapid sensitivity for the design of new devices.

The design of anion–π interactions and hydrogen bonds for the recognition of chloride, bromide and nitrate anions

The role of anions in several biochemical processes has given rise to enormous interest in the identification/exploration of compounds with the potential ability to recognize anions. Here, an anthracene-squaramide conjugated compound, O2C4[NH(C14H10)][(NH(C6H6)], has been modified through the substitutions (i) H → F and (ii) H → OH at the anthracene and benzene rings to improve the capabilities of these structures for recognizing chloride, bromide, and nitrate anions. Through an energy decomposition analysis method, the recognition of the anions is chiefly identified as a non-covalent process. H → F substitutions at the benzene ring and, principally, the anthracene ring favor anion recognition, since H → F substitutions create a π-acid region in the aromatic ring, as indicated based on the molecular electrostatic potential surfaces. Similarly, H → OH substitutions also improve the recognition of anions, which is related to the establishment of partly covalent chemical bonds of the form O-H(Cl-, Br- and O-), which are verified based on the quantitative analysis of the maximum and minimum values of the molecular electrostatic potential surfaces and the quantum theory of atoms in molecules method. The presence of large electron density has a key role in the recognition of Cl- anions, and the more favorable electrostatic interactions between the anthracene structure and Br- anions, relative to NO3- anions, mean that receptorBr- interactions are more attractive than receptorNO3- ones. These data can contribute to the design of structures with the relevant abilities to interact with anions.

Charge neutral halogen bonding tetradentate-iodotriazole macrocycles capable of anion recognition and sensing in highly competitive aqueous media.

A series of neutral tetradentate halogen bonding (XB) macrocycles, comprising of two bis-iodotriazole XB donors were synthesised in 60-70% yields via a stepwise CuAAC-mediated cyclisation strategy. Extensive 1H NMR anion titration experiments reveal halide binding affinities are critically dependent on the substitution pattern of the xylyl spacer unit. The meta-substituted macrocycle remarkably displays cooperative tetradentate XB-halide anion recognition in highly competitive 40% aqueous-organic D2O/acetone-d6 (40 : 60, v/v) solvent mixtures. Integration of para-xylyl and naphthyl spacer units generates extended macrocyclic cavities, capable of selective oxalate recognition. Furthermore, preliminary fluorescence exeperiments reveal dicarboxylate specific sensing can be achieved through monitoring of the naphthylene centred emission.

Fluorometric detection of fluoride and thiocyanate ions using novel anthrapyrazolone derivatives

Anion recognition and sensing via artificial receptors have attracted a great deal of attention due to their significant role in chemical, biological, medical, and environmental applications. In the present investigation, we have demonstrated facile and straightforward synthesis of three low molecular weight fluorophore molecules designated as 2,7 - dihydrobenzo [1,2,3 - cd:4,5,6-c'd']bis(indazole) [DHBBI], 2-(benzo[1,2,3-cd:4,5,6-c'd']bis(indazole)-2(7H)-yl)ethanol [DHBBI-OH] and 2-(benzo[1,2,3-cd:4,5,6-c'd']bis(indazole)-2(7H)-yl)ethyl methacrylate [DHBBI-MA] for the fluorometric detection of fluoride and thiocyanate ions in solution phase. DHBBI was synthesized by a condensation reaction of 1,5-dichloroanthraquinone with hydrazine monohydrate. DHBBI-OH was synthesized by the reaction of DHBBI with 2-bromoethanol using K 2 CO 3 as base whereas, DHBBI-MA was synthesized by the reaction of DHBBI-OH with methacrylic anhydride using dimethylamino pyridine (DMAP). Novel three molecules were characterized by 1 H NMR, FT-IR, HR-MS and UV–Vis spectroscopy. The strong fluorescence nature of the compounds was further analyzed towards the detection of different ions. All the compounds DHBBI, DHBBI-OH, and DHBBI-MA showed turn on fluorescence behavior for fluoride (F - ) ion and turn off fluorescence behavior for thiocyanate (SCN - ) ion respectively.

Anion recognition by anthracene appended ortho-aminomethylphenylboronic acid: a new PET-based sensing mechanism

Carboxylate, phosphate and sulphate anions form hydrogen bonded complexes with the B(OH)2 group of the receptor 1 producing a turn-off fluorescence response, while the malonate monoanion induces the opposite turn-on effect.

A calix[4]pyrrole-based linear supramolecular polymer constructed by orthogonal self-assembly.

A calix[4]pyrrole having a ureidopyrimidinone unit was successfully synthesized from its alcohol-functionalized congener and further used for the first time to obtain a thermo- and chemical-responsive linear supramolecular polymer via orthogonal self-assembly comprising a combination of quadruple hydrogen bonding and anion recognition.

Anion recognition by halogen bonding and hydrogen bonding bis(triazole)-imidazolium [2]rotaxanes.

A novel halogen bonding (XB) bis(iodotriazole)-imidazolium motif is incorporated into the axle component of a [2]rotaxane via a discrete chloride anion template directed clipping methodology. 1H NMR anion titration experiments reveal the interlocked host is capable of strong halide and sulfate oxoanion binding in competitive aqueous-organic CDCl3/CD3OD/D2O (45 : 45 : 10 v/v) solvent mixtures. In comparison to a hydrogen bonding rotaxane analogue, which exhibited no pronounced selectivity between Cl-, I- and SO42-, the axle iodo-triazole donor motifs of the XB rotaxane modulate the anion recognition preference towards the lighter halides Cl- ≈ Br- > SO42- > I-.

Design of supramolecular systems capable of recognizing anions uniquely by aliphatic C–H⋯anion hydrogen bonds: theoretical insights

Anions play important roles in the environment. The anionic recognition through –CH polarized groups has been elucidated from DFT calculations.

Iodide ion receptors: shape-persistent macrocycles of syn/anti configurations

A local induced fit mechanism following a conformational selection in the recognition of iodide anions is reported.

Revisiting imidazolium receptors for the recognition of anions: highlighted research during 2010-2019.

Imidazolium based receptors selectively recognize anions, and have received more and more attention. In 2006 and 2010, we reviewed the mechanism and progress of imidazolium salt recognition of anions, respectively. In the past ten years, new developments have emerged in this area, including some new imidazolium motifs and the identification of a wider variety of biological anions. In this review, we discuss the progress of imidazolium receptors for the recognition of anions in the period of 2010-2019 and highlight the trends in this area. We first classify receptors based on motifs, including some newly emerging receptors, as well as new advances in existing receptor types at this stage. Then we discuss separately according to the types of anions, including ATP, GTP, DNA and RNA.

Carbazole sulfonamide-based macrocyclic receptors capable of selective complexation of fluoride ion.

Two carbazole sulfonamide-based macrocycles 1 and 2 were facilely synthesized and carefully evaluated for their anion recognition properties. The obtained results revealed that macrocycle 1 with a 1,3-xylyl linker was able to bind fluoride ion more strongly and selectively in acetonitrile medium than its strong competitors (like acetate and dihydrogen phosphate anions), with a large binding constant (Ka) of 50 878 M−1. More importantly, an exclusive fluoride recognition was achieved for macrocycle 1 in the more polar DMSO-d6 solution, albeit with a moderate affinity of Ka = 147 M−1. Compared with macrocycle 1, macrocycle 2 bearing a 2,6-lutidinyl linkage exhibited a remarkable change not only in the anion affinity but also in the anion selectivity, although with only a slight difference in their molecular structures.

Synthesis and aqueous anion recognition of an imidazolium-based nonacationic cup.

An imidazolium-based nonacationic cup (1·9X; X = PF6- or Cl-) was synthesized via step-by-step SN2 reactions without using any template. The water-soluble 1·9Cl- as a molecular container can encapsulate anionic nucleoside triphosphate and dinucleotide molecules (e.g., ATP and NADH) inside its cavity through hydrogen bonds and electrostatic interactions in aqueous solution.

An Ir3L2 complex with anion binding pockets: photocatalytic E-Z isomerization via molecular recognition.

A molecular host with photosensitizing centers provides photo-responsive host-guest properties based on its molecular recognition ability. Here, we construct a self-assembled photoactive Ir(iii) cage-shaped complex that contains anion binding pockets on its rim. The anion recognition ability of the complex enables efficient catalysis of the visible-light-induced E-Z isomerization of an anionic styrene derivative.

Orientation of the α-CD component of [2]rotaxanes affects their specific molecular recognition behaviour

An α-CD component enhanced the anion recognition ability of the urea moiety and the deprotonation of the phenol moiety in the axle component in orientationally isomeric [2]rotaxanes with the OH groups on the wide rim of the α-CD, respectively.

Synthesis of Single Isomeric Complexes with Dissymmetric Structures Using Macrocyclic Homooligomers

AbstractBottom‐up chemical synthesis to construct intricate molecules has been a profound challenge. An effective approach is to utilize organic ligands and metal ions, but the formation of a single product among other possible candidates has proven difficult for dissymmetric structures. We now report the synthesis of single isomeric complexes with dissymmetric structures using the mismatch in the coordination valences of macrocyclic homooligomers and metal ions. A series of amide‐cyclodextrin derivatives possessing multiple 2,2′‐bipyridyl (bpy) groups forms mononuclear complexes whose specific three bpy groups are linked in the fac‐Λ configuration. The intermolecular coordination of the β‐cyclodextrin metal complex produces a dissymmetric cyclodextrin trimer as a single isomer, whose initially equivalent 21 (=7×3) bipyridylamide‐pyranose units are placed in different environments. Furthermore, we realize chiral recognition of amino acid anions utilizing the distinctive amide groups arranged on the unsymmetrically fixed scaffold.

Synthesis of Single Isomeric Complexes with Dissymmetric Structures Using Macrocyclic Homooligomers.

Bottom-up chemical synthesis to construct intricate molecules has been a profound challenge. An effective approach is to utilize organic ligands and metal ions, but the formation of a single product among other possible candidates has proven difficult for dissymmetric structures. We now report the synthesis of single isomeric complexes with dissymmetric structures using the mismatch in the coordination valences of macrocyclic homooligomers and metal ions. A series of amide-cyclodextrin derivatives possessing multiple 2,2'-bipyridyl (bpy) groups forms mononuclear complexes whose specific three bpy groups are linked in the fac-Λ configuration. The intermolecular coordination of the β-cyclodextrin metal complex produces a dissymmetric cyclodextrin trimer as a single isomer, whose initially equivalent 21 (=7×3) bipyridylamide-pyranose units are placed in different environments. Furthermore, we realize chiral recognition of amino acid anions utilizing the distinctive amide groups arranged on the unsymmetrically fixed scaffold.

Imidazolinium-based Multiblock Amphiphile as Transmembrane Anion Transporter.

Transmembrane anion transport is an important biological process in maintaining cellular functions. Thus, synthetic anion transporters are widely developed for their biological applications. Imidazolinium was introduced as anion recognition site to a multiblock amphiphilic structure that consists of octa(ethylene glycol) and aromatic units. Ion transport assay using halide-sensitive lucigenin and pH-sensitive 8-hydroxypyrene-1,3,6-trisulfonate (HPTS) revealed that imidazolinium-based multiblock amphiphile (IMA) transports anions and showed high selectivity for nitrate, which plays crucial roles in many biological events. Temperature-dependent ion transport assay using 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) indicated that IMA works as a mobile carrier. 1 H NMR titration experiments indicated that the C2 proton of the imidazolinium ring recognizes anions via a (C-H)+ ⋅⋅⋅X- hydrogen bond. Furthermore, all-atom molecular dynamics simulations revealed a dynamic feature of IMA within the membranes during ion transportation.

Unprecedented tunable hydrophobic effect and anion recognition triggered by AIE with Hofmeister series in water

An unprecedented tunable hydrophobic effect in self-assembly of a small cationic organic fluorophore (NI-TPy+)-based with aggregation-induced emission (AIE) property was realized in aqueous solution. The amplification of hydrophobicity was found to be significantly dependent upon the increasing aggregates of NI-TPy+, which enabled the study of the hydrophobic binding of chaotropic anions with the Hofmeister series.

Colorimetric sensing and anion recognition by Kalanchoe flower-like ligand and its transition metal complexes with polarized N-H interaction motifs

Herein we report the selective sensing of fluoride ion with kalanchoe flower-like ligand, L ( 2‑chloro‑3‑((3‑dimethylamino)propylamino)naphthalene‑1,4‑dione) and it's metal (K1-Cu(II), K2-Co(II), K3-Zn(II)) complexes. The morphology and anion sensing properties of the L and K1-K3 compounds were investigated with microscopic and spectroscopic techniques. 1H NMR titration was carried out to understand the fluoride ion interaction with the N-H interacting site of the ligand and its metal complexes. Furthermore, quantum chemical calculations were conducted to rationalize the interaction between chemosensors and anions.