Theoretical studies of proton transfers. 1. The potential energy surfaces of the identity reactions of the first- and second-row non-metal hydrides with their conjugate bases

Gronert, Scott

doi:10.1021/ja00075a047

Cited by 142 publications

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“…The fitting of the experimental data using theoretical calculations. 44 The addition of water to the medium leads to a reduction in the magnitude of the binding constant due to the fact that it interacts with the anion, lowering its ability to act as a base. With less basic anions, such CH 3 COO -and H 2 PO 4 -, hydrogen-bonded complexes of 2a and the anion are formed, as indicated by the yellow coloration obtained in solution.…”

Section: Resultsmentioning

confidence: 99%

Anionic chromogenic chemosensors highly selective for fluoride or cyanide based on 4-(4-Nitrobenzylideneamine)phenol

Nicoleti

Marini

Zimmermann

et al. 2012

J. Braz. Chem. Soc.

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4-(4-Nitrobenzylideneamine)phenol was used in two strategies allowing the highly selective detection of F -and CN -. Firstly, the compound in acetonitrile acts as a chromogenic chemosensor based on the idea that more basic anions cause its deprotonation (colorless solution), generating a colored solution containing phenolate. The discrimination of CN -over F -was obtained by adding 1.4% water to acetonitrile: water preferentially solvates F -, leaving the CN -free to deprotonate the compound. Another strategy involved an assay comprised of the competition between phenolate dye and the analyte for calix [4]pyrrole in acetonitrile, a receptor highly selective for F -. Phenolate and calix[4]pyrrole form a hydrogen-bonded complex, which changes the color of the medium. On the addition of various anions, only F -was able to restore the original color corresponding to phenolate in solution due to the fact that the anion dislodges phenolate from the complexation site.

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Section: Resultsmentioning

confidence: 99%

Anionic chromogenic chemosensors highly selective for fluoride or cyanide based on 4-(4-Nitrobenzylideneamine)phenol

Nicoleti

Marini

Zimmermann

et al. 2012

J. Braz. Chem. Soc.

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“…[9] This is a rather common behaviour in the presence of an excess of fluoride, due to the formation of the particularly stable HF 2 À hydrogen bonding self-complex. [10] Also, the solvent plays a role in controlling N-H deprotonation. In particular, deprotonation and formation of the [HA 2 ]…”

Section: Introductionmentioning

confidence: 99%

Metal‐Controlled Anion‐Binding Tendencies of the Thiourea Unit of Thiosemicarbazones

Amendola

Boiocchi

Fabbrizzi

et al. 2008

Chemistry A European J

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The terdentate ligand 3 (LH, 2-formylpyridine 4-thiosemicarbazone) forms with FeII and NiII 2:1 complexes of octahedral geometry of formula [MII(LH)2]2+. X-ray diffraction studies have shown that in both complexes the thiourea moieties of the coordinated thiosemicarbazones are exposed to the outside and are prone to establish hydrogen-bonding bifurcate interactions with oxoanions. However, spectrophotometric studies in CHCl3 solution have shown that only the poorly basic NO3 - ion is able to form authentic hydrogen-bond complexes with thiourea subunits, whereas all the other investigated anions (CH3COO-, NO2 -, F-) induce deprotonation of the N-H fragment. The extreme enhancement of the thiourea acidity is based on the coordinative interaction of the sulphur atom with the metal, which stabilises the thiolate form, and it is much higher than that exerted by any other covalently linked electron-withdrawing substituent, for example, --NO2.

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“…The interaction of (H 2 PO 4 ) 2 2À dimers with ureas has been previously documented in solution and in the solid state. [15,16] In the present case, the interaction with the second H 2 PO 4 À reduces the basicity of the urea-bound phosphate, which gives back a proton to the receptor. Thus, complex b in Scheme 4 is formed, in which the internal H 2 PO 4 À ion receives, on one side, two parallel hydrogen bonds from the receptor and, on the other side, donates two parallel hydrogen bonds to the external H 2 PO 4 À .…”

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confidence: 73%

“…[15] Deprotonation of BH + also took place to a significant extent in the 10 À5 m solution, after the addition of 1 equiv of F It is observed that, on addition of the first equivalent of fluoride, the band for the receptor at 285 nm undergoes a moderate redshift, typically associated with the formation of a hydrogen-bonded complex. Moreover, a new band simultaneously develops at 335 nm; such a band, as mentioned before, results from the charge-transfer transition from a deprotonated NÀH fragment.…”

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confidence: 99%

Moderate and Advanced Intramolecular Proton Transfer in Urea–Anion Hydrogen‐Bonded Complexes

Baggi

Boiocchi

Fabbrizzi

et al. 2011

Chemistry A European J

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The study of the interactions of the three urea-based receptors AH, BH(+) and CH(2+) with a variety of anions, in MeCN, has made it possible to verify the current view that hydrogen bonding is frozen proton transfer from the donor (the urea N-H fragment in this case) to the acceptor (the anion X(-)). The poorly acidic, neutral receptor AH establishes two equivalent hydrogen bonds N-H···X(-), with all anions, including CH(3)COO(-) and F(-), in which moderate proton transfer from N-H to the anion takes place. The strongly acidic, dicationic receptor CH(2+) forms, with most anions, complexes in which two inequivalent hydrogen bonds are present: one involving moderate proton transfer (N-H···X(-)) and one in which advanced proton transfer has taken place, described as N(-)···H-X. The degree of proton advancement is directly related to the basic tendencies of the anion. The cationic receptor BH(+) of intermediate acidic properties only forms complexes with two inequivalent hydrogen bonds (moderate+advanced proton transfer) with CH(3)COO(-) and F(-), and complexes with two equivalent hydrogen bonds (moderate proton transfer) with all the other anions. Moreover, [B···HF] and [C···HF](+), on addition of a second F(-) ion, lose the bound HF molecule to give HF(2)(-). Release of CH(3)COOH, with the formation of [CH(3)COOH···CH(3)COO](-), also takes place with the [B···CH(3)COOH] complex in the presence of a large excess of anion.

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Theoretical studies of proton transfers. 1. The potential energy surfaces of the identity reactions of the first- and second-row non-metal hydrides with their conjugate bases

Cited by 142 publications

References 0 publications

Anionic chromogenic chemosensors highly selective for fluoride or cyanide based on 4-(4-Nitrobenzylideneamine)phenol

Anionic chromogenic chemosensors highly selective for fluoride or cyanide based on 4-(4-Nitrobenzylideneamine)phenol

Metal‐Controlled Anion‐Binding Tendencies of the Thiourea Unit of Thiosemicarbazones

Moderate and Advanced Intramolecular Proton Transfer in Urea–Anion Hydrogen‐Bonded Complexes

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