@article {42504, title = {Ratiometric detection of Cr3+ and Hg2+ by a naphthalimide-rhodamine based fluorescent probe}, journal = {Inorganic Chemistry}, volume = {51}, year = {2012}, month = {JAN}, pages = {1769{\textendash}1777}, abstract = {

Newly synthesized rhodamine derivatives, L1 and L2, are found to bind specifically to Hg2+ or Cr3+ in presence of large excess of other competing ions with associated changes in their optical and fluorescence spectral behavior. These spectral changes are significant enough in the visible region of the spectrum and thus, allow the visual detection. For L1, the detection limit is even lower than the permissible [Cr3+] or [Hg2+] in drinking water as per standard U.S. EPA norms; while the receptor, L2 could be used as a ratiometric sensor for detection of Cr3+ and Hg2+ based on the resonance energy transfer (RET) process involving the donor naphthalimide and the acceptor Cr3+/Hg2+-bound xanthene fragment. Studies reveal that these two reagents could be used for recognition and sensing of Hg2+/Cr3+. Further, confocal laser microscopic studies confirmed that the reagent L2 could also be used as an imaging probe for detection of uptake of these ions in A431 cells.

}, doi = {10.1021/ic202073q}, author = {Mahato, Prasenjit and Saha, Sukdeb and Suresh, E. and Liddo, Rosa Di and Parnigotto, Pier Paolo and Conconi, Maria Teresa and Kesharwani, Manoj K. and Ganguly, Bishwajit and Das, Amitava} } @article {42501, title = {Recognition of Hg 2+ and Cr 3+ in physiological conditions by a rhodamine derivative and its application as a reagent for cell-imaging studies}, journal = {Inorganic Chemistry}, volume = {51}, year = {2012}, month = {DEC}, pages = {336{\textendash}345}, abstract = {

A new rhodamine-based receptor, derivatized with an additional fluorophore (quinoline), was synthesized for selective recognition of Hg2+ and Cr3+ in an acetonitrile/HEPES buffer medium of pH 7.3. This reagent could be used as a dual probe and allowed detection of these two ions by monitoring changes in absorption and the fluorescence spectral pattern. In both instances, the extent of the changes was significant enough to allow visual detection. More importantly, the receptor molecule could be used as an imaging reagent for detection of Hg2+ and Cr3+ uptake in live human cancer cells (MCF7) using laser confocal microscopic studies. Unlike Hg(ClO4)2 or Hg(NO3)2 salts, HgCl2 or HgI2 failed to induce any visually detectable change in color or fluorescence upon interaction with L1 under identical experimental conditions. Presumably, the higher covalent nature of HgII in HgCl2 or HgI2 accounts for its lower acidity and its inability to open up the spirolactam ring of the reagent L1. The issue has been addressed on the basis of the single-crystal X-ray structures of L1{\textperiodcentered}HgX2 (X{\textendash} = Cl{\textendash} or I{\textendash}) and results from other spectral studies.

}, doi = {10.1021/ic2017243}, author = {Saha, Sukdeb and Mahato, Prasenjit and Reddy, Upendar G. and Suresh, E. and Chakrabarty, Arindam and Baidya, Mithu and Ghosh, Sudip K. and Das, Amitava} } @article {42500, title = {Recognition of Hg2+ion through restricted imine isomerization: crystallographic evidence and imaging in live cells}, journal = {Organic Letters}, volume = {14}, year = {2012}, month = {JUN}, pages = {2980{\textendash}2983}, abstract = {

A newly synthesized imine-based receptor (L) showed remarkable specificity toward the Hg2+ ion in aqueous media over other metal ions. Coordination of L to Hg2+ induces a turn-on fluorescence response. This was explained based on the restricted imine isomerization along with PET on coordination to Hg2+. X-ray structural evidence tends to favor a C{\textendash}C bond rotation rather than C=N isomerization for adopting a favorable conformation in L for coordination to Hg2+. This reagent could be used for imaging the accumulation of Hg2+ ions in HeLa cells.

}, doi = {10.1021/ol3009733}, author = {Mandal, Amal Kumar and Suresh, Moorthy and Das, Priyadip and Suresh, E. and Baidya, Mithu and Ghosh, Sudip K. and Das, Amitava} }