Search

A new type of easily synthesized rhodamine-based chemosensor L3, with potential NO2 donor atoms, selectively and rapidly recognizes Hg2+ ions in the presence of all biologically relevant metal ions and toxic heavy metals. A very low detection limit (78 nM) along with cytoplasmic cell imaging applications with no or negligible cytotoxicity indicate good potential for in vitro/in vivo cell imaging studies. SEM and TEM studies reveal strongly agglomerated aggregations in the presence of 5 mM SDS which turn into isolated core shell microstructures in the presence of 9 mM SDS. The presence of SDS causes an enhanced quantum yield (φ) and stability constant (Kf) compared to those in the absence of SDS. Again, the FI of the [L3–Hg]2+ complex in an aqueous SDS (9 mM) medium is unprecedentedly enhanced (∼143 fold) compared to that in the absence of SDS. All of these observations clearly manifest in the enhanced rigidity of the [L3–Hg]2+ species in the micro-heterogeneous environment significantly restricting its dynamic movements. This phenomenon may be ascribed as an aggregation induced emission enhancement (AIEE). The fluorescence anisotropy assumes a maximum at 5 mM SDS due to strong trapping (sandwiching) of the doubly positively charged [L3–Hg]2+ complex between two co-facial laminar microstructures of SDS under pre-miceller conditions where there is a strong electrostatic interaction that causes an improved inhibition to dynamic movement of the probe-mercury complex. On increasing the SDS concentration there is a phase transition in the SDS microstructures and micellization starts to prevail at SDS ≥ 7.0 mM. The doubly positively charged [L3–Hg]2+ complex is trapped inside the hydrophobic inner core of the micelle which is apparent from the failure to quench the fluorescence of the complex on adding 10 equivalents of H2EDTA2− solution but in the absence of SDS it is quenched effectively. [ABSTRACT FROM AUTHOR]

A 2-hydroxy-5-methyl-benzene-1,3-dicarboxaldehyde di-oxime based turn-on blue emission fluorescent probe was found to recognize both AsO2− and H2AsO4− in a purely aqueous medium in intra and extra-cellular conditions. Self-organization of the ligand in the absence and presence of AsO2− and H2AsO4− was investigated by DLS, optical microscopy, optical fluorescence microscopy and FE-SEM methods. [ABSTRACT FROM AUTHOR]

A diformyl-p-cresol (DFC)-8-aminoquinoline based dual signaling probe was found to exhibit colorimetric and fluorogenic properties on selective binding towards Mg2+ and Zn2+. Turn-on fluorescent enhancements (FE) as high as 40 fold and 53 fold in 9 : 1 MeCN/water (v/v) at pH 7.2 in HEPES buffer for Mg2+ and Zn2+, respectively, were observed. The binding constants determined from the fluorescence titration data are: K = (1.52 ± 0.21) × 105 M−1 and (9.34 ± 4.0) × 103 M−2 at n = 1 and 0.5, for Mg2+ and Zn2+, respectively. The L : M binding ratios were also determined by Job's method, which support the above findings. This is further substantiated by HRMS analysis. Due to solubility in mixed organo-aqueous solvents as well as cell permeability it could be used for the in vitro/in vivo cell imaging of Mg2+ and Zn2+ ions with no or negligible cytotoxicity. This probe could be made selective towards Mg2+ over Zn2+ in the presence of TPEN, both under intra- and extracellular conditions and is superior to other Mg2+ probes which suffer from selectivity of Mg2+ over Ca2+ or Zn2+. Furthermore the dissociation constant (Kd = 6.60 μM) of the Mg2+-(DFC-8-AQ) complex is far lower than the so far reported Mg2+ probes which fall in the mM range. [ABSTRACT FROM AUTHOR]

A diformyl-p-cresol (DFC)-8-aminoquinoline based dual signaling probe was found to exhibit colorimetric and fluorogenic properties on selective binding towards Mg(2+) and Zn(2+). Turn-on fluorescent enhancements (FE) as high as 40 fold and 53 fold in 9 : 1 MeCN/water (v/v) at pH 7.2 in HEPES buffer for Mg(2+) and Zn(2+), respectively, were observed. The binding constants determined from the fluorescence titration data are: K = (1.52 ± 0.21) × 10(5) M(-1) and (9.34 ± 4.0) × 10(3) M(-2) at n = 1 and 0.5, for Mg(2+) and Zn(2+), respectively. The L : M binding ratios were also determined by Job's method, which support the above findings. This is further substantiated by HRMS analysis. Due to solubility in mixed organo-aqueous solvents as well as cell permeability it could be used for the in vitro/in vivo cell imaging of Mg(2+) and Zn(2+) ions with no or negligible cytotoxicity. This probe could be made selective towards Mg(2+) over Zn(2+) in the presence of TPEN, both under intra- and extracellular conditions and is superior to other Mg(2+) probes which suffer from selectivity of Mg(2+) over Ca(2+) or Zn(2+). Furthermore the dissociation constant (Kd = 6.60 μM) of the Mg(2+)-() complex is far lower than the so far reported Mg(2+) probes which fall in the mM range.