00895nas a2200193 4500008004100000245008100041210006900122260000800191300001400199490000700213520024200220100001800462700002400480700002600504700002400530700002300554700001700577856010700594 2011 eng d00aReceptor design and extraction of inorganic fluoride ion from aqueous medium0 aReceptor design and extraction of inorganic fluoride ion from aq cMAY a7398-74000 v473 a

A receptor with acidic methylene hydrogens is found to act as an efficient binding mode for F−. This reagent could as well be used for selective and quantitative extraction of F− from the aqueous solution of NaF and sea water.

1 aDas, Priyadip1 aMandal, Amal, Kumar1 aKesharwani, Manoj, K.1 aSuresh, Eringathodi1 aGanguly, Bishwajit1 aDas, Amitava uhttp://library.ncl.res.in/content/receptor-design-and-extraction-inorganic-fluoride-ion-aqueous-medium01289nas a2200205 4500008004100000245011900041210006900160260000800229300001600237490000700253520056400260100002400824700002000848700001800868700001500886700001800901700002100919700001700940856012600957 2012 eng d00aRecognition of Hg2+ion through restricted imine isomerization: crystallographic evidence and imaging in live cells0 aRecognition of Hg2ion through restricted imine isomerization cry cJUN a2980–29830 v143 a

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–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.

1 aMandal, Amal, Kumar1 aSuresh, Moorthy1 aDas, Priyadip1 aSuresh, E.1 aBaidya, Mithu1 aGhosh, Sudip, K.1 aDas, Amitava uhttp://library.ncl.res.in/content/recognition-hg2ion-through-restricted-imine-isomerization-crystallographic-evidence-and01865nas a2200169 4500008004100000245014500041210006900186260000800255300001600263490000700279520120700286100002401493700002001517700001801537700001701555856012301572 2012 eng d00aRestricted conformational flexibility of a triphenylamine derivative on the formation of host-guest complexes with various macrocyclic hosts0 aRestricted conformational flexibility of a triphenylamine deriva cMAR a3906–39170 v183 a

Herein, we report the host–guest-type complex formation between the host molecules cucurbit[7]uril (CB[7]), β-cyclodextrin (β-CD), and dibenzo[24]crown-8 ether (DB24C8) and a newly synthesized triphenylamine (TPA) derivative 1X3 as the guest component. The host–guest complex formation was studied in detail by using 1H NMR, 2D NOESY, UV/Vis fluorescence, and time-resolved emission spectroscopy. The chloride salt of the TPA derivative was used for recognition studies with CB[7] and β-CD in an aqueous medium. The restricted internal rotation of the guest molecule on complex formation with either of these two host molecules was reflected in the enhancement of the emission quantum yield and the average excited-state lifetime for the triphenylamine-based excited states. Studies with DB24C8 as the host molecule were performed in dichloromethane, a medium that maximizes the noncovalent interaction between the host and guest fragments. The Förster resonance energy transfer (FRET) process involving DB24C8 and 1(PF6)3, as the donor and acceptor fragments, respectively, was established by electrochemical, steady-state emission, and time-correlated single-photon counting studies.

1 aMandal, Amal, Kumar1 aSuresh, Moorthy1 aDas, Priyadip1 aDas, Amitava uhttp://library.ncl.res.in/content/restricted-conformational-flexibility-triphenylamine-derivative-formation-host-guest02504nas a2200205 4500008004100000022001400041245016500055210006900220260007100289300001600360490000700376520165600383100001802039700002802057700002102085700002302106700002302129700001702152856012902169 2013 eng d a0020-166900aRole of metal ion in specific recognition of pyrophosphate ion under physiological conditions and hydrolysis of the phosphoester linkage by alkaline phosphatase0 aRole of metal ion in specific recognition of pyrophosphate ion u a1155 16TH ST, NW, WASHINGTON, DC 20036 USAbAMER CHEMICAL SOCcOCT a11034-110410 v523 a

Complexes synthesized from Zn(II), Cu(II), and Cd(II), using a dipicolyl amine derivative (L), showed unique specificity toward pyrophosphate ion (PPi or P4O74-) among all other common anionic analytes, including different biologically significant phosphate ion (PO43-, H2PO42-) or phosphate-ion-based nucleotides, such as AMP, ADP, ATP, and CTP. However, the relative affinities of PPi toward these three metal complexes were found to vary and follow the order K-a(L.Zn-PPi) > are given in units of (L.Cu-PPi)(a) >= K-a(L.Cd-PPi). Luminescence responses of the receptor L were substantial on binding to Zn2+ and Cd2+, while relatively a much smaller luminescence response was observed in the presence of Cu2+. Luminescence responses of L.M-PPi (M is Zn2+, Cd2+, and Cu2+) were further modified on binding to the PPi ion. This could be utilized for quantitative detection of PPi in physiological condition as well as for developing a real time ``turn-on'' (for L.Zn and L.Cu) and ``turn-off'' (for L.Cd) fluorescence assay for evaluating the enzymatic activity of alkaline phosphatase (ALP). Experimental results revealed how the subtle differences in the binding affinities between PPi and M in L.M (M is Zn2+, Cd2+, and Cu2+), could influence the cleavage of the phosphoester linkage in PPi by ALP. The DFT calculations further revealed that the hydrolytic cleavage of the metal ion coordinated phosphoester bond is kinetically faster than that for free PPi and thus, rationalized the observed difference in the cleavage of the phosphoester bond by an important mammalian enzyme such as ALP in the presence of different metal complexes.

1 aDas, Priyadip1 aChandar, Nellore, Bhanu1 aChourey, Shishir1 aAgarwalla, Hridesh1 aGanguly, Bishwajit1 aDas, Amitava uhttp://library.ncl.res.in/content/role-metal-ion-specific-recognition-pyrophosphate-ion-under-physiological-conditions-and-0