Synthesis and Anion-Selective Complexation of Homobenzylic Tripodal Thiourea Derivatives (original) (raw)
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New aroyl thioureas; N-nicotinoyl-N'-(4-nitrophenyl) thiourea (3a) and N-nicotinoyl-N'-(2-nitrophenyl) thiourea (3b) were synthesized and studied as anion-binding receptors. Upon adding tetrabutyl ammonium halides (fluoride, chloride bromide and iodide), cyanide and hydroxide ions to their solutions in DMSO respectively, the colour of the solutions has shown striking changes from pale yellow to brillant yellow or red. The binding effects of the anions were investigated by UV-VIS spectroscopic method and 1 H NMR titrations.
New Journal of Chemistry, 2009
The synthesis and structural characterisation of three chiral bis-naphthalene thiourea receptors (1-3) derived from (R)-(+)-1-(1-naphthyl)ethylamine and (S)-(À)-1-(1-naphthyl)ethylamine are reported along with spectroscopic studies to screen their potential as anion receptors/sensors. Their solid state structures were analysed by X-ray crystallography and their ability to bind anions such as acetate and phosphate in DMSO solution investigated by 1 H NMR, absorption, fluorescence and circular dichroism spectroscopy. Scheme 1 Synthesis of compounds 1-3.
European Journal of Inorganic Chemistry, 2012
Tris(2-aminoethyl)amine (tren) based 4-cyanophenyl-substituted tripodal L, tris{[(4-cyanophenyl)amino]ethyl}thiourea receptor, was synthesized and explored thoroughly for anion recognition in solution by NMR spectroscopy and isothermal titration calorimetry (ITC) as well as in the solid state by single-crystal X-ray diffraction studies. Anion recognition properties of L were further exploited toward the extraction of sulfate as well as fluoride from aqueous media using a liquid-liquid extraction technique. A solution-state anion binding study using NMR spectroscopy in [D 6 ]DMSO and ITC measurements in dry acetonitrile show a relatively higher association constant of L with halides (Fand Clover er oxyanions (H 2 PO 4 and HSO 4-). The single-crystal X-ray structural analysis of complex 1 reveals a monotopic encap-[a]
Synthesis and anion recognition studies of a dipodal thiourea-based sensor for anions
Tetrahedron Letters, 2014
A new dipodal thiourea-based sensor (L) has been synthesized and its binding affinity toward a variety of anions has been investigated in solution and solid state. The colorimetric studies show a significant color change of L in the presence of fluoride, dihydrogen phosphate, and acetate in DMSO. The data obtained from UV-vis titrations is consistent with the results of the colorimetric observations. As investigated by 1 H NMR titrations, the sensor binds an anion in a 1:1 binding mode showing the binding trend in the order of F À > Cl À > Br À > I À for halides and H 2 PO À 4 > CH 3 COO À , SO 2À 4 > HSO À 4 > NO À 3 , ClO 0040-4039/$ -see front matter Ó
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A thiourea-based tripodal receptor L substituted with 3-nitrophenyl groups has been synthesized, and the binding affinity for a variety of anions has been studied by 1 H NMR titrations and nuclear Overhauser enhancement spec-troscopy experiments in dimethyl sulfoxide-d 6. As investigated by 1 H NMR titrations, the receptor binds an anion in a 1:1 binding mode, showing the highest binding and strong selectivity for sulfate anion. A competitive colorimetric assay in the presence of fluoride suggests that the sulfate is capable of displacing the bound fluoride, showing a sharp visible color change. The strong affinity of L for sulfate was further supported by UV−vis titrations and density functional theory (DFT) calculations. Time-dependent DFT calculations indicate that the fluoride complex possesses a different optical absorption spectrum (due to charge transfer between the fluoride and the surrounding ligand) than the sulfate complex, reflecting the observed colorimetric change in these two complexes. The receptor was further tested for its biocompatibility on primary human foreskin fibroblasts and HeLa cells, exhibiting an excellent cell viability up to 100 μM concentration.
Physical Chemistry Research, 2016
A theoretical density functional theory (DFT) study was performed on a series of the neutral N-phenylthiourea substituents (p-OC2H5, p-CH3, m-CH3, H, p-Cl, p-Br, m-Cl, and p-NO2) as the sensor of acetate and fluoride anions. The hydrogen bond character was analyzed as a scale of the sensing activity. It was confirmed that hydrogen bond between the p-NO2 derivatives of N-phenylthiourea and fluoride anion is stronger than acetate in CH3CN as a solvent. Therefore, N-(p-nitrophenyl) thiourea acts as a better chemical sensor in fluoride detection. For the investigation of the N-H bond properties, donor-acceptor interaction energy through the natural bond orbital analysis was obtained. Topology analysis by estimation of the kinetic and potential energy densities of the hydrogen bonds was done. Finally, some correlations between the quantum chemistry descriptors and sensing characters of the studied compounds were obtained and analyzed.
Tetrahedron Letters, 2015
Anion binding properties of a quinoline-based tripodal tris-thiourea receptor have been studied for several oxoanions including perchlorate, nitrate, hydrogen sulfate, and dihydrogen phosphate by 1 H NMR and UV-vis titrations in DMSO. Results show that the receptor selectively binds dihydrogen phosphate with a 1:1 stoichiometry. Ab initio calculations based on density functional theory (DFT) suggest that the dihydrogen phosphate is encapsulated within the host's cavity via six NHÁ Á ÁO and two NÁ Á ÁOH interactions.
RSC Adv., 2015
Tris(3-aminopropyl)amine-based tripodal urea and thiourea receptors, tris ([(4-cyanophenyl)amino]propyl)urea (L1) and tris ([(4-cyanophenyl)amino]propyl)thiourea (L2), have been synthesized and their anion binding properties have been investigated for halides and oxoanions. As investigated by 1 H NMR titrations, each receptor binds an anion with a 1 : 1 stoichiometry via hydrogen-bonding interactions (NH/anion), showing the binding trend in the order of F À > H 2 PO 4 À > HCO 3 À > HSO 4 À > CH 3 COO À > SO 4 2À > Cl À > Br À > I in DMSO-d 6 . The interactions of the receptors were further studied by 2D NOESY, showing the loss of NOESY contacts of two NH resonances for the complexes of F À , H 2 PO 4 À , HCO 3 À , HSO 4 À or CH 3 COO À due to the strong NH/anion interactions. The observed higher binding affinity for HSO 4 À than SO 4 2À is attributed to the proton transfer from HSO 4 À to the central nitrogen of L1 or L2
Substituent effect on conformational preference and anion binding of thiourea receptors
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2-hydroxy aromatic Schiff bases that exhibit ESIPT (excited state intramolecular proton transfer) ESIPT or TICT (twisted intramolecular charge transfer) photodeactivation pathways emerge as promising candidates for fluorescent sensors. In this computational work, the influence of various substituents differing in the electronic properties on conformational preferences in the ground and S 1 excited state for a series of 2-hydroxy-1-naphthylmethylene-hydrazine-based ligands is systematically studied based on (TD)DFT calculations. In order to shed light on physical factors which might determine the obtained conformational preferences extensive bonding analyses are performed. The results highlight the crucial role of a substituent ability to form not only well-established intramolecular hydrogen bonds (e.g. O-H•••N), but also unintuitive non-classic weak interactions (e.g. C-H•••O, C-H•••N and C-H•••H-C) in the modulation of the equilibrium between naphthol-imine and keto-amine forms, and planar or twisted conformations, and thus, determination of photophysical properties of the considered bases.
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