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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: A simple colorimetric and ratiometric fluorescent anion sensor 1, 3,6-dichloro-1,8-dinitrocarbazole, was rationally designed and synthesized on basis of the mechanism of intramolecular charge transfer (ICT). In DMSO solutions of 1, the presence of AcO−, F− and H2PO4 − gave birth to the formation of a 2:1 host-to-guest complex, which was synchronously accompanied by a ‘naked-eye’ color change from light yellow to purple, a red-shift of the absorption spectrum and a blue-shift of the emission spectrum. [Copyright &y& Elsevier]

Abstract: Two novel highly sensitive colorimetric acetate anion receptors: 4-phenylazo-2-hydroxy-benzaldehyde 4-nitrophenylhydrazone (1) and 4-phenylazo-2-hydroxy-benzaldehyde 2,4-dinitrophenylhydrazone (2) based on azo derivative have been designed and synthesized. UV–vis experiments show that receptor 1 and receptor 2 can selectively recognize acetate in DMSO and even in 9/1 DMSO/H2O (v/v) mixtures. Meanwhile the color changes induced by anions can provide a way of detection by ‘naked-eye’. The further insights to the nature of interactions between receptor 1, 2 and AcO− have been investigated by 1H NMR titration experiments. [Copyright &y& Elsevier]

Abstract: A colorimetric sensor 1,N,N′-di-(2-hydroxy-5-(phenldiazenyl)benzaldehyde)-1,3-diiminothiourea for acetate in DMSO and 9/1 DMSO/H2O (v/v) mixtures was designed and synthesized. The binding ability evaluated by UV–vis experiment reveals that sensor 1 can selectively recognize acetate. In addition, the color changes induced by anions can provide a way of detection by ‘naked-eye’. The further insights to the nature of interactions between the sensor 1 and AcO− were investigated by 1H NMR titration experiments in 9/1 DMSO-d 6 /H2O (v/v). [Copyright &y& Elsevier]

Abstract: A novel and efficient receptor based on the phenylhydrazone derivatives is successfully developed and applied to the acetate anion recognition, indicating that the origin of special preference for acetate (AcO−) anion maybe the structure well matching between the host and the guest. The sensor changes its color so obviously on addition of the acetate ions and that may make the naked-eye recognition in DMSO and even in DMSO/H2O (95/5) solution come true. Also, the anion binding ability determinations were performed by UV–vis titration and 1H NMR titration experiments with different anions in the solutions mentioned. The fluorescence enhancement can also be observed after the host is coordinated with the AcO− anion and excited by light wavelength at 280nm. [Copyright &y& Elsevier]

Abstract: A sensitive colorimetric sensor (1) based on 4,5-dinitrobenzene-1,2-diamine was designed and synthesized. Binding of anions such as AcO−, F− and results in a notable change in the visible region of spectrum (an approximately 90nm red shift), which can be detected by the ‘naked-eye’. Furthermore, the binding ability was evaluated by UV–vis titration experiments as following: AcO− >F− > ≫Cl−, Br−, I−. The nature of the color change of 1 induced by AcO− was due to the intramolecular charge transfer (ICT) which was confirmed by X-ray crystal structure and 1H NMR titration spectra. [Copyright &y& Elsevier]

Abstract: A novel positive homotropic allosteric system 1 based on 3-methylpyrozole-5-one-4-one-2′,4′-dinitrophenylhydrazone was designed, synthesized and characterized. Colorimetric and fluorescent sensing of anions was achieved in physiological condition (pH 7.4), resulting from the positive homotropic allosterism of 1 induced by anions tested. In particular, the compound 1 exhibited a two-step response to the strong basic anions such as F−. In the first step, the hydrazone form of 1 interacted with anions through hydrogen bonding with an obvious color change from yellow to orange upon addition of 0.3equiv. of anions. In the second step, with further addition of anions, the hydrazone form of 1 was shifted to the azophenol form, whose anion binding was accompanied with an orange-to-purple color change. In addition, the receptor 1 exhibited a fluorescent enhancement response to anions exploiting two possible signaling transduction mechanisms: (1) inhibition of photoinduced electronic transfer (PET) and (2) binding-induced rigidity of the host molecule. [Copyright &y& Elsevier]

Abstract: A simple colorimetric and fluorescent anion chemosensor based on amide moieties, 6-nitro-1,4-dihydroquinoxaline-2,3-dione has been designed, synthesized and characterized by 1H NMR, ESI-MS and elemental analyses. The strong basic anions such as F− and AcO− resulted in significant decrease in fluorescent emission intensity of the compound 1, accompanied synchronously with a dramatic color change from colorless to deep yellow in organic medium. 1H NMR titration experiments shed light on the nature of the interactions between 1 and the anions. [Copyright &y& Elsevier]

Abstract: A novel and simple fluorescent receptor bearing thiourea moiety as recognition site was described. The recognition behavior of the receptor toward different anions was investigated in DMSO/H2O (95:5 v/v) and dry DMSO through two various channels: the colorless-yellow color change and a remarkable enhancement of the fluorescence. And the enhancement of the fluorescence was attributed to an anion-induced increase of the rigidity of the host molecule. [Copyright &y& Elsevier]