Synthesis and anion recognition of neutral receptors based on multiamide calyx[4]arene

~~Synthesis and anion recognition of neutral receptors based on multiamide calyx[4]arene~~     

Fading of a novel colorimetric receptor after recognizing H2PO4−

A novel selective and sensitive colorimetric receptor 1 (1, 10-phenanthroline-2, 9-dialdehyde bis-(-p-nitrophenylureasemicarbo-hydrazone)) based on urea showing distinctive color fading phenomenon towards H₂PO₄^? ion was reported. Fancifully, the recognition process of receptor 1 to H₂PO₄^? was not interfered by the existence of others anions. We have probed the binding mechanism of 1-H₂PO₄^? that H₂PO₄^? ion induced competitive hydrogen binding process via intramolecular hydrogen-bond by UV–vis, fluorescence, ¹H NMR titrations and ESI-MS experiments.     

Synthesis of the anionic fluororeceptors based on thiourea and amide groups and recognition property for α,ω-dicarboxylate

Three new neutral receptors (1, 2 and 3) containing thiourea and amide groups were synthesized by simple steps in good yields. The binding properties for anions of 1, 2 and 3 were examined by UV-vis, fluorescence, and ¹H NMR spectroscopy. Receptors 1, 2 and 3 all had a better adipate anion selectivity by comparison with other dicarboxylate anions. The association constants of 1, 2 and 3 with adipate were higher as compared to other anions (malonate, succinate, glutarate). In particular, a distinct color change was observed from light yellow to orange-red upon addition of adipate to the solution of 1 in DMSO. The UV-vis and fluorescence data indicate that a 1:1 stoichiometry complex is formed between compound 1, 2 or 3 and dicarboxylate anions through hydrogen bonding interactions.     

Design and synthesis of novel tweezer anion receptors based on deoxycholic acid

A novel type of molecular tweezer receptors based on deoxycholic acid has been designed and synthesized and their binding properties were examined by UV-vis spectral titration. These molecular tweezers showed a high selectivity toward F- over Cl-,Br-, I-, AcO-, H2PO4-.     

Design and synthesis of azaindole heterocycle decorated new scaffold in fluorometric sensing of F− and H2PO4−

7-Azaindole has been used in designing new molecular structure 1 on enediyne spacer for its application in anion sensing. New structure 1 has been established as efficient fluorescent sensor of H₂PO₄⁻ and F⁻ ions in CH₃CN containing 1% DMSO. While in presence of H₂PO₄⁻ the emission at 418 nm is decreased to the significant extent in nonratiometric fashion, a ratiometric response in presence of F⁻ is noted with a sharp isoemissive point and two anions are effectively distinguished over a series of other anions tested. A similar study on model compound 2 with indole motifs is done to prove the pivotal role of extra ring nitrogen in azaindole of 1 in the binding process.     

Selective “naked-eye” sensing of acetate ion based on conformational flexible amide-pyridinium receptor

A simple pincer-shape anion receptor L1 containing amide-pyridinium as binding unit was synthesized and its anion binding properties were investigated by UV–Vis, NMR titration spectra and molecular simulation. L1 displayed better affinity toward AcO^? ion with visible color change compared with other investigated anions, including F^?, H₂PO₄ ^?, Cl^?, Br^?, I^?, NO₃ ^? and HSO₄ ^? ions. The selectivity was ascribed to the synergistic effects arising from hydrogen bonding, electrostatic interaction and induced-fit process.     

Synthesis and structural characterization of a barium coordination polymer based on a μ2-monoatomic bridging 4-nitrobenzoate

Abstract

The synthesis, spectral characterization, crystal structure and properties of [Ba(H₂O)₂(NMF)₂(4-nba)₂], 1 (NMF = N-methylformamide; 4-nba = 4-nitrobenzoate), are reported. ¹H and ¹³C NMR spectral data reveal the presence of NMF in 1. A strong band at 1660?cm^?1 in the infrared spectrum indicates the binding of amide oxygen to Ba(II) which is confirmed by the single crystal structure. The unique Ba(II) in 1 situated on a mirror plane exhibits nine coordination and is bonded to two symmetry related monodentate terminal NMF ligands via the amide oxygen, and a terminal aqua ligand. The μ₂-monoatomic bridging binding mode of each of a crystallographically independent 4-nba ligand and a unique water ligand link the Ba(II) cations into an infinite chain extending along a, leading to the formation of a 1D coordination polymer with Ba···Ba separations of 4.2522(3) Å. In the chain, the {BaO₉} polyhedra are linked in a face sharing fashion. Thermal decomposition of 1 results in the formation of BaCO₃ residue. A comparative study of the structural chemistry of several barium coordination polymers is described.     

The synthesis and crystal structure of a hydrated magnesium phosphate Mg3(PO4)2·4H2O

The synthesis and crystal structure of a novel hydrated magnesium phosphate is described. The crystal structure was solved from powder X-ray diffraction data. Mg₃(PO₄)₂·4H₂O crystallizes in the orthorhombic space group Cmc2₁ (No. 36) with a=8.41087(9) Å, b=17.3850(2) Å, c=12.8034(1) Å, V=1872.15(4) ų and Z=8. The structure consists of sheets stacked along [010], which are linked by edge sharing octahedral Mg₂O₆(H₂O)₄ dimers. Within the sheets there are infinite edge-sharing chains of Mg octahedra along [100]. The compound has been further characterized by ³¹P MAS NMR spectroscopy and thermogravimetric analysis. The crystal structure of two dehydrated variants existing around 200 (Mg₃(PO₄)₂·2.5H₂O) and 275 °C (Mg₃(PO₄)₂·2H₂O) remain unknown.     

Selective self-assembly synthesis of MnV2O6·4H2O with controlled morphologies and study on its thermal decomposition

The MnV₂O₆·4H₂O with rod-like morphologies was synthesized by solid-state reaction at low heat using MnSO₄·H₂O and NH₄VO₃ as raw materials. XRD analysis showed that MnV₂O₆·4H₂O was a compound with monoclinic structure. Magnetic characterization indicated that MnV₂O₆·4H₂O and its calcined products behaved weak magnetic properties. The thermal process of MnV₂O₆·4H₂O experienced three steps, which involves the dehydration of the two waters of crystallization at first, and then dehydration of other two waters of crystallization, and at last melting of MnV₂O₆. In the DSC curve, the three endothermic peaks were corresponding to the two steps thermal decomposition of MnV₂O₆·4H₂O and melting of MnV₂O₆, respectively. Based on the Kissinger equation, the average values of the activation energies associated with the thermal decomposition of MnV₂O₆·4H₂O were determined to be 55.27 and 98.30?kJ?mol^?1 for the first and second dehydration steps, respectively. Besides, the thermodynamic function of transition state complexes (??H ^??, ??G ^?? , and ??S ^?? ) of the decomposition reaction of MnV₂O₆·4H₂O were determined.     

Synthesis of open-framework iron phosphates, [C5N2H14]2[FeIII2F2(HPO4)4]·2H2O and [C5N2H14][FeIII4(H2O)4F2(PO4)4], with one- and three-dimensional structures

The hydrothermal syntheses and structures of two new open-framework iron phosphates, [C₅N₂H₁₄]₂[Fe^III₂F₂(HPO₄)₄]·2H₂O, I, and [C₅N₂H₁₄][Fe^III₄(H₂O)₄F₂(PO₄)₄], II, are presented. While the structure of I consist of FeO₄F₂ octahedra and HPO₄ terahedra linked to form one-dimensional structure, that of II consist of FeO₄(H₂O)₂, FeO₄(H₂O)F, FeO₄F₂ and PO₄ units connected to give rise to a three-dimensional structure. The structure of I resembles the naturally occurring mineral tancoite while II resembles the iron phosphate, ULM-12, [C₆N₂H₁₄][Fe₄(PO₄)₂F₂(H₂O)₃]. Magnetic susceptibility studies indicate anti-ferromagnetic behavior in both the compounds with T_N=200 and 175 K for I and II, respectively. Crystal data: I, monoclinic, space group=P2₁/n (no. 14). a=7.2261(6), b=16.5731(14), c=11.0847(10) Å, β=97.265(2)°, V=1316.8(2) Å³, Z=4, ρ_calc=1.952 g cm⁻¹, μ_(MoKα)=1.446 mm⁻¹, R₁=0.0448 and wR₂=0.1141 for 1882 data [I>2σ(I)]; for II, monoclinic, space group=P2₁/n (no. 14). a=9.9691(3), b=12.4013(3), c=17.3410(3) Å, β=103.762(1)°, V=2082.32(9) Å³, Z=4, ρ_calc=2.576 g cm⁻¹, μ_(MoKα)=3.162 mm⁻¹, R₁=0.0510 and wR₂=0.1064 for 2979 data [I>2σ(I)].     

Fluorimetric detection and discrimination of α-amino acids based on tricyclic basic dyes and cucurbiturils supramolecular assembly

A sensor array made by combining four fluorescent tricyclic basic dyes with cucurbiturils is able to identify and discriminate 18 α-amino acids up to 10⁻⁴ M without the need of enzyme activation.     

A vibrational spectroscopic study of the mixed anion mineral sanjuanite Al2(PO4)(SO4)(OH)·9H2O

The mineral sanjuanite Al2(PO4)(SO4)(OH)·9H2O has been characterised by Raman spectroscopy complimented by infrared spectroscopy. The mineral is characterised by an intense Raman band at 984 cm(-1), assigned to the (PO4)3- ν1 symmetric stretching mode. A shoulder band at 1037 cm(-1) is attributed to the (SO4)2- ν1 symmetric stretching mode. Two Raman bands observed at 1102 and 1148 cm(-1) are assigned to (PO4)3- and (SO4)2- ν3 antisymmetric stretching modes. Multiple bands provide evidence for the reduction in symmetry of both anions. This concept is supported by the multiple sulphate and phosphate bending modes. Raman spectroscopy shows that there are more than one non-equivalent water molecules in the sanjuanite structure. There is evidence that structural disorder exists, shown by the complex set of overlapping bands in the Raman and infrared spectra. At least two types of water are identified with different hydrogen bond strengths. The involvement of water in the sanjuanite structure is essential for the mineral stability.     

Hydrothermal Synthesis and Crystal Structure of a New Phosphonate： {[Cu（1,10-phen）]2-（H2O3PCH2C6H4C6H4CH2PO3H）2-（HO3PCH2C6H4C6H4CH2PO3H） }n

1 INTRODUCTION Metal organophosphonates have attracted considerable attention for over three decades due to their potential or practical applications, include- ing ion exchanges[1, 2], molecular sensors[3] and optics[4, 5]. Recently, a number of porous m…     

Pincer ligands based on α-amino acids: III. New ligands based on 4-substituted phenols and their copper complexes. Enantioselective recognition of tyrosine

Reactions of L-methionine, L-serine, and L-valine with 5-substituted-2-hydroxybenzene-1,3-dicarbaldehydes gave a series of chiral Schiff base pincer ligands which were reduced to the corresponding diamines. The new Schiff base ligands reacted with copper(II) chloride to form dinuclear copper complexes which were found to be capable of recognizing tyrosine enantiomers in aqueous solution. The structure of the complexes was determined on the basis of their spectral parameters.     

Homology modelling of the human adenosine A2B receptor based on X-ray structures of bovine rhodopsin, the β2-adrenergic receptor and the human adenosine A2A receptor

A three-dimensional model of the human adenosine A_2B receptor was generated by means of homology modelling, using the crystal structures of bovine rhodopsin, the β₂-adrenergic receptor, and the human adenosine A_2A receptor as templates. In order to compare the three resulting models, the binding modes of the adenosine A_2B receptor antagonists theophylline, ZM241385, MRS1706, and PSB601 were investigated. The A_2A-based model was much better able to stabilize the ligands in the binding site than the other models reflecting the high degree of similarity between A_2A and A_2B receptors: while the A_2B receptor shares about 21% of the residues with rhodopsin, and 31% with the β₂-adrenergic receptor, it is 56% identical to the adenosine A_2A receptor. The A_2A-based model was used for further studies. The model included the transmembrane domains, the extracellular and the intracellular hydrophilic loops as well as the terminal domains. In order to validate the usefulness of this model, a docking analysis of several selective and nonselective agonists and antagonists was carried out including a study of binding affinities and selectivities of these ligands with respect to the adenosine A_2A and A_2B receptors. A common binding site is proposed for antagonists and agonists based on homology modelling combined with site-directed mutagenesis and a comparison between experimental and calculated affinity data. The new, validated A_2B receptor model may serve as a basis for developing more potent and selective drugs.     

Preparation and recognition performance of ratio-fluorescent probe based on sulfadiazine imprinted polymersEI北大核心CSCD

A novel ratio-fluorescent probe based on molecular imprinting polymer ( MIP) for the detection of sulfadiazine was prepared by using nitrogen-doped carbon quantum dots (N-CQDs) as the fluorescence response signal, silica-embedded cadmium telluride quantum dots ( CdTe QDs) as the fluorescence reference signal, sulfadiazine ( SDZ) as template molecule, acrylamide as functional monomer, N, N-methyl bisacrylamide as crosslinking agent and 2,2-Azobisisobutyronitrile as initiator. The results showed that the probe has a core-shell structure and fluorescence sensitive to SDZ, by the characterization of scanning electron microscopy, transmission electron microscopy, and fluorescence spectrophotometer. Under the wavelength of 360 nm, the ratio-fluorescent signal of probe showed a linear response with SDZ concentration in the range of 0-100 μmol / L with the detection limit of 11 nmol / L. Also, the ratio-fluorescent probe was applied to the detection of SDZ with a recovery of 92. 0%-95. 1% and relative standard deviation (RSD) of 3. 6% in real water samples. © 2022, Youke Publishing Co.,Ltd. All rights reserved.     

Packing and properties of composite phase change energy storage materials based on SiC nanowires and Na2SO4·10H2O

Journal of Thermal Analysis and Calorimetry - SiC nanowires were prepared by sol–gel sintering at high temperature, then shaped and encapsulated Na2SO4·10H2O-based composite phase change...     

Two binuclear complexes containing the enrofloxacinate anion: Cd2(C19H21N3O3F)4(H2O)2 · 4H2O and Pb2(C19H21N3O3F)4 · 4H2O

The syntheses and crystal structures of the closely related but non-isostructural Cd₂(C₁₉H₂₁N₃O₃F)₄(H₂O)₂?·?4H₂O (1) and Pb₂(C₁₉H₂₁N₃O₃F)₄?·?4H₂O (2) are described, where C₁₉H₂₁N₃O₃F^? is enrofloxacinate (enro). Both compounds contain centrosymmetric, binuclear, neutral complexes incorporating a central diamond-shaped M₂O₂ (M?=?Cd, Pb) structural unit. The Cd²⁺ coordination polyhedron in 1 is a CdO₆ trigonal prism, including one coordinated water. The Pb²⁺ coordination polyhedron in 2 can be described as a very distorted square-based PbO₅ pyramid, although two additional short Pb?···?O (<3.1?Å) contacts are also present. In the crystal of the cadmium complex, O–H?···?O hydrogen bonds lead to a layered structure. In the lead compound, O–H?···?O and O–H?···?N interactions lead to chains in the crystal. Crystal data: 1: C₇₆H₉₆Cd₂F₄N₁₂O₁₈, M _r?=?1766.45, triclinic, P 1, a?=?12.185(2)?Å, b?=?12.306(3)?Å, c?=?14.826(3)?Å, α?=?68.15(3)°, β?=?70.28(3)°, γ?=?86.11(3)°, V?=?1938.2(7)?ų, Z?=?1, T?=?298 K, R(F)?=?0.030, wR(F ²)?=?0.079. 2: C₇₆H₈₈F₄N₁₂O₁₆Pb₂, M _r?=?1920.00, triclinic, P 1, a?=?12.0283(4)?Å, b?=?12.7465(4)?Å, c?=?13.0585(4)?Å, α?=?83.751(1)°, β?=?74.635(1)°, γ?=?81.502(1)°, V?=?1904.3(1)?ų, Z?=?1, T?=?298?K, R(F)?=?0.021, wR(F ²)?=?0.049.