Structural, Spectroscopic, and Reactivity Properties of N2S2(thioether)‐O(amide)‐Ligated HgII Complexes: The First Examples of HgII‐Mediated Amide Cleavage

Makowska-Grzyska, M.; Doyle, Kelly; Allred, Russell A.; Arif, Atta M.; Bebout, Deborah C.; Berreau, Lisa M.

doi:10.1002/ejic.200400771

Cited by 13 publications

(10 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…61 The Hg-O(1) bond length of 2.572(3) Å suggests a relatively weak interaction. The Hg-N(2) distance, 2.436(3) Å, is slightly longer than that of the analogous Hg-N bond in [Hg(beppa)(ClO 4 )]ClO 4 , where beppa = {N,N-bis(2-ethylthio)ethyl-N-[(6-pivaloylamido-2-pyridyl)methyl]amine, and the bond length of relevance is 2.412(6) Å 66. Overall, the structure of 6 is similar to that of [(beppa)Hg (ClO 4 )]ClO 4 , although mercury in the latter is described as six-coordinate because of a weak interaction with a perchlorate ion (3.01 Å).…”

mentioning

confidence: 90%

Turn-On and Ratiometric Mercury Sensing in Water with a Red-Emitting Probe

2007

View full text Add to dashboard Cite

The synthesis, photophysical properties, and Hg(II) binding of a red-emitting sensor for mercuric ion are presented. 2-[11-[(2-[[Bis-(2-ethylsulfanylethyl)amino]methyl]phenylamino)methyl]-3-hydroxy-10-oxo-10H-benzo[c]xanthen-7-yl]benzoic acid (MS5) is based on the seminaphthofluorescein chromophore and employs a thioether-rich metal-binding unit. This sensor affords both turn-on and single-excitation dual-emission ratiometric Hg(II) detection in aqueous solution. The fluorescence response of MS5 is Hg(II)-specific, and the probe is selective for Hg(II) over alkali and alkaline earth metals, most divalent first-row transition metal ions, and the Group 12 congeners Zn(II) and Cd(II). MS5 binds Hg(II) reversibly and can be recycled. The EC50 for 1 microM MS5 is 910 nM, and a lower detection limit of 50 nM is obtained when employing 500 nM probe. X-ray crystallographic studies using a salicylaldehyde-based model of MS5 are also presented. 2-[(2-[[Bis-(2-ethylsulfanylethyl)amine]methyl]phenylamine)methyl]phenol coordinates Hg(II) with two thioether sulfur atoms, two amino nitrogen atoms, and a phenol oxygen atom arranged in a distorted trigonal bipyramidal geometry. Studies of natural water samples spiked with mercuric salts indicate that MS5 can rapidly detect Hg(II) in such complex solutions and demonstrate its potential utility in the field.

show abstract

mentioning

confidence: 90%

Turn-On and Ratiometric Mercury Sensing in Water with a Red-Emitting Probe

2007

View full text Add to dashboard Cite

show abstract

“…If the thermodynamically more stable form is the pseudo‐octahedral complex, it may rearrange with increased temperature to produce a pseudo‐trigonal‐prismatic geometry that is the reactive species for intramolecular amide methanolysis. Of relevance to this chemistry, we note that a trigonal‐prismatic type of geometry, as is proposed for the Zn II cation shown in Figure 7, has been previously identified in cadmium and mercury “parent” complexes of the bmppa and beppa { N , N ‐bis(2‐ethylthio)ethyl‐ N ‐[(6‐pivaloylamido‐2‐pyridyl)methyl]amine} ligands 16,24. These complexes undergo methanolysis of the amide when treated with 1 equiv.…”

Section: Resultsmentioning

confidence: 53%

Coenzyme Q Functionalized CdTe/ZnS Quantum Dots for Reactive Oxygen Species (ROS) Imaging

Qin

et al. 2011

Chemistry A European J

View full text Add to dashboard Cite

Quantum dots (QDs) have been widely used for fluorescent imaging in cells. In particular, surface functionalized QDs are of interest, since they possess the ability to recognize and detect the analytes in the surrounding nanoscale environment based on electron and hole transfer between the analytes and the QDs. Here we demonstrate that fluorescence enhancement/quenching in QDs can be switched by electrochemically modulating electron transfer between attached molecules and QDs. For this purpose, a number of redox-active coenzyme Q (CoQ) disulfide derivatives [CoQC(n)S](2) were synthesized with different alkyl chain lengths (n=1, 5, and 10). The system supremely sensitive to NADH (nicotinamide adenine dinucleotide) and superoxide radical (O(2)(.)(-)), and represents a biomimetic electron-transfer system, modeling part of the mitochondrial respiratory chain. The results of our in situ fluorescence spectroelectrochemical study demonstrate that the reduced state of [CoQC(n)S](2) significantly enhanced the fluorescence intensity of CdTe/ZnS QDs, while the oxidized state of the CoQ conjugates quench the fluorescence to varying degrees. Fluorescence imaging of cells loaded with the conjugate QD-[CoQC(n)S](2) displayed strikingly differences in the fluorescence depending on the redox state of the capping layer, thus introducing a handle for evaluating the status of the cellular redox potential status. Moreover, an MTT assay (MTT=3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) proved that the cytotoxicity of QDs was significantly reduced after immobilization by CoQ derivatives. Those unique features make CoQ derivatived QDs as a promising probe to image redox coenzyme function in vitro and in vivo.

show abstract

“…It is known that Hg 2+ catalyzes the hydrolysis in amides 19 as might well be the case for this system. Moreover, the existence of a critical point closing the chelate ring in [Hg(m-adgha)] 2+ suggests that the formation of this species might be closely related to the hydrolysis of the amide ligand that leads to the imidazole appearance in solution.…”

Section: Discussionmentioning

confidence: 97%