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New Pd(ii) and Pt(ii) complexes with ONN donor pincer ligand are synthesized. Antiproliferative activity of the complexes is explored towards HCT116, HepG2, MCF-7 and A549 cell lines.

A new highly sensitive, reversible, reusable and fluorogenic “turn-on” switch (HBTC) has been fabricated for the sole detection of Al3+.

A new chromone-based fluorescent probe (HMPM) is developed for the selective detection of Pd2+.

A new ratiometric fluorescent probe (E)-2-(benzo[d]thiazol-2-yl)-3-(8-methoxyquinolin-2-yl)acrylonitrile (HQCN) was synthesised by the perfect blending of quinoline and a 2-benzothiazoleacetonitrile unit. The probe can selectively detects hydrazine and hypochlorite with two different outputs.

A novel colorimetric and fluorescent sensing probe (E)-3-(4-(9H-carbazol-9-yl)phenyl)-2-(benzo[d]thiazol-2-yl)acrylonitrile (CBTA) was synthesized and characterized by spectroscopic techniques. CBTA displayed “turn off” fluorescence in the presence of cyanide with relatively high selectivity...

A new ratiometric fluorescent probe (

A new fluorescent "on-off-on" probe (BIPQ) is designed and developed which selectively binds with Hg2+; its emission intensity is quenched almost 40-fold at 455 nm without interference from other metal cations. On gradual addition of I- to the solution of BIPQ-Hg2+, the emission reverts to its original intensity. The limits of detection of BIPQ for Hg2+ and I- are found to be on the order of 3.12 × 10-9 and 5.48 × 10-8 M, respectively, which shows clearly that BIPQ can sense Hg2+ at a very minute level. DFT and TDDFT studies are conducted with the probe to establish similarity between theoretical and experimental outcomes. Finally, to demonstrate its practical benefit in biological fields, live cell imaging experiments with BIPQ are carried out to detect Hg2+ in human AGS gastric cancer cell lines.

A new ESIPT based fluorescent probe has been introduced for selective detection of Zn2+ in human breast cancer cells. The designed probe exhibits a prominent ratiometric fluorescence change along with a sharp blue shift of ∼71 nm which can be attributed to the hampering of the ESIPT process. The probe is efficient enough to detect Zn2+ solely in the presence of other biologically relevant cations with a limit of detection value of 1.6 × 10−7 M. The experimentally observed changes in the structure and absorption properties of the probe after complete addition of Zn2+ were further studied by density functional theory (DFT) and time dependent density functional theory (TDDFT) calculations. Moreover, the dip-stick experiment with this probe displays both absorption and fluorescence color changes after exposure to Zn2+ which also turns out to be a potential application for the probe. Live cell imaging studies have been carried out using human breast cancer cells (MCF-7) and tissues.

In this paper, a quinoline-based (BIMQ) probe was developed, and it displayed ratiometric detection of organophosphorus (OP) chemical vapor threat DCP. Upon addition of the nerve agent mimic diethyl chlorophosphate (DCP), a fluoroscence color change from blue to cyan was observed. The chemodosimeter BIMQ underwent nucleophilic substitution with DCP, followed by a ring closure to yield the final product and showed an explicit fluorescence response towards DCP. The probe BIMQ selectively detected DCP in the presence of other toxic analytes. The detection limit of BIMQ for DCP was established to be in the order of 10−8 M in the solution phase, which suggests that BIMQ can efficiently detect DCP at a very low level. This ratiometric switch has a potential application as a portable kit for detecting DCP vapour with high sensitivity. TDDFT calculations were carried out in order to unveil the electronic properties theoretically.

A new fluorescent “turn-on” probe (DHMC) has been designed and synthesized to selectively detect Pd2+ among other cations at physiological pH. Upon incremental addition of Pd2+ into the probe solution, a “turn-on” emission enhancement was noticed with a ∼69 nm red shift at 562 nm in CH3CN/H2O (4/1, v/v) solution. The limit of detection and binding constant values have been determined and found to be on the order of 7.4 × 10−8 M and 1.7 × 105 M−1 respectively, which clearly suggests that the probe is very efficient in detecting Pd2+ at very minute levels and also the DHMC–Pd2+ complexation is stable enough too. A brilliant application of the probe has been explored which indicates that DHMC can detect Pd2+ in the solid state too. DFT and TDDFT calculations are carried out to interpret the electronic structure and sensing mechanism.

A hybrid carbazole-benzothiazole based chemodosimeter (CB) has been synthesized for the colorimetric and fluorogenic detection of cyanide ion (CN–). Intra-molecular charge transfer (ICT) played important role for the detection of CN– in DMSO-water (4/1, v/v, pH=7.2) solution. Upon treatment of CN– to the probe solution, results bleaching of the original yellow color of the probe with a large blue shift in absorption spectra. A large enhancement of the fluorescence intensity with a slight red shift is observed after addition of CN– to the probe (CB). Here, the nucleophilic addition of CN– inhibits the intra-molecular charge transfers (ICT) process responsible for the large enhancement of emission. The chemical reaction involved behind the sensing of CN– has been confirmed through 1H NMR and mass spectroscopic studies. The density function theory (DFT) and time-dependent density function theory (TDDFT) has also been conducted to support the experimental findings.

A new fluorescent "on-off-on" probe (BIPQ) is designed and developed which selectively binds with Hg

Increased oxidative stress in metabolic complications like type 2 diabetes, dyslipidemia and cardiovascular disorders exerts potential health hazards in many facets. Enhanced production of reactive oxygen species (ROS) due to increased oxidative stress promotes the damage of many biologically important macromolecules. Hypochlorous acid (HOCl), a microbicidal agent is also known to be an important ROS sub-species. An enhanced generation of endogenous HOCl due to diseased condition therefore can be detrimental to health. In present work, a new quinoline-diaminomaleonitrile based probe (HQMN) has been designed for the selective detection of hypochlorite. The probe in hand shows a selective ratiometric emission change towards OCl−. The probe behaves as a highly selective and sensitive tool for the detection of OCl− over other analytes with a fast response time (within 100 s). Bioimaging study revealed that HQMN can detect endogenous OCl− in human monocytes and an increase in endogenous HOCl concentration has been witnessed in diabetic condition compared to healthy control. Thus HQMN can be used as an excellent fluorescent probe for dynamic tracking of hypochorite in living biological cells especially to identify diabetic conditions.

A new fluorescent probe (SAPH) has been introduced which shows specific sensing towards Zn2+ and Hg2+ at two different wavelength maxima at physiological pH. The probe shows a brilliant ratiometric red shift in emission spectra upon addition of Zn2+ at 678 nm while upon addition of Hg2+ it shows a turn-on ratiometric emission enhancement with a red shift at 647 nm. Job's plot confirms the 1 : 1 complexation for both Zn2+ and Hg2+. The binding constants have been calculated using the Benesi–Hildebrand equation and found to be 3.03 × 105 M−1 and 6.05 × 104 M−1 respectively for SAPH–Zn2+ and SAPH–Hg2+. DFT and TDDFT studies are conducted using the probe to establish a similarity between theoretical and experimental outcomes.

The fluorogenic chemosensor 3-(((2-hydroxy-4-methylphenyl)imino)methyl)-[1,1′-biphenyl]-4-ol (H2L) efficiently detects Zn2+ and Al3+ ions and subsequently fluoride ion in methanol–water (4/1, v/v, pH = 7.2) solution. The probe itself is non-emissive but upon treatment with Al3+ and Zn2+, it exhibits high fluorescence emission at two different wavelengths of 546 nm and 529 nm, respectively. Both excited-state intramolecular proton transfer (ESIPT) and chelation enhanced fluorescence (CHEF) processes play important roles in the enhancement of fluorescence intensity. Chelation of Zn2+ and Al3+ with the probe (H2L) inhibits CN isomerization and ESIPT which consequently enhances the emission intensity. The emission intensity of H2L–Al3+ is selectively quenched upon titration with F− anions. The structure of the probe is confirmed by the single crystal X-ray diffraction method. The electronic structure and sensing mechanism of the probe (H2L) are supported by density functional theory (DFT) and time-dependent density functional theory (TDDFT).

A novel coumarin based azo-phenol ligand (H2L) has been synthesized and characterized by several spectroscopic techniques. An almost 16 fold enhancement of emission intensity has been observed upon gradual addition of Mg2+ to H2L in DMSO:H2O (1:5 v/v) medium while it has no significant effect in emission intensity even in presence of other metal ions. The emission intensity of L-Mg2+ complex has almost quenched on gradual addition of F− to it. The limit of detection for both Mg2+ and F− are of 10−8 M order, hence the newly developed chemosensor is highly efficient in detecting Mg2+ and F− in very minute levels. The chemosensor can even detect Mg2+ in the intracellular region of human lung cancer cells (A549 cells).

A potent fluorescence ‘turn-on’ receptor (HL) based on rhodamine and coumarin moieties for the detection of Hg2+ and Al3+ is synthesized by condensation of rhodamine 6G hydrazide and 4-hydroxy-3-acetylcoumarin. In presence of Al3+ and/or Hg2+ the receptor (HL) exhibits deep pink colouration and a sharp band at 528 nm is appeared in UV–vis titration. Upon gradual addition of Al3+ and/or Hg2+ to the solution of HL significant enhancement of fluorescence intensity is observed at 564 nm in MeCN:H2O (1:5, v/v) medium. The receptor is strongly bound to Al3+ and/or Hg2+ and the association constants (Ka) are found to be 1.74 × 104 and 1.04 × 104 M− 1 for Al3+ and Hg2+ respectively.

A highly sensitive and selective coumarin based chemosensor H 2 L for the efficient detection of Al 3+ has been developed. The synthesized chemosensor H 2 L is efficient in detecting Al 3+ over other metal ions which are commonly obtained in various physiological and environmental samples. H 2 L shows fluorescence ‘turn-on’ response at 610 nm in presence of Al 3+ , without the interference of other metal ions. The resulting H 2 L-Al 3+ complex behave as a sequential chemosensor for F − , by showing quenching of emission intensity upon addition of F − to it. This quenching of emission intensity is only specific for F − and is not hampered due to the presence of other anions that commonly coexist with F − in various environmental solutions. Theoretical calculations using DFT/B3LYP method has been used to get insight into the sensing mechanism as well as electronic structure of the synthesized chemosensor H 2 L. H 2 L is efficient in detecting Al 3+ in the intracellular region of human A549 cell and also exhibits an INHIBIT logic gate with Al 3+ and F − as chemical inputs by monitoring the emission mode at 610 nm.

In this study, a triphenylamine–benzimidazole (TPIM)-functionalised switch has been fabricated for ratiometric recognition of organophosphorus (OP) chemical vapor. Interestingly, upon addition of the nerve agent mimic diethyl chlorophosphate (DCP), a prominent color change from colorless to yellow along with a fluorescence color change from cyan to deep yellow was noticed. The chemodosimeter (TPIM) undergoes tandem nucleophilic substitution reaction with DCP and shows a specific colorimetric and fluorescence alteration. The probe selectively detects DCP over other toxic substituents studied. In addition, the detection limit of TPIM for DCP was found to be in the order of 10−8 M in solution phase using fluorescence method. We have also developed a transportable kit for DCP using our probe (TPIM), which can detect DCP vapour with high sensitivity.

A new fluorescence probe (H2L) is designed and synthesized for efficient and selective detection of Zn(II). H2L exhibits a “turn-on” fluorescence response with substantial enhancement of emission intensity with Zn2+ even in presence of other coexisting cations found in various environmental and biological samples. The calculated value of limit of detection (LOD) is 1.73 × 10−9 M. Exploiting the reversibility of the probe in presence of EDTA, an INHIBIT logic gate is constructed with Zn2+ and EDTA as chemical inputs. DFT and TDDFT calculations are used to interpret electronic structures and elucidate the sensing mechanism. Cytotoxicity study by MTT method with human breast cancer cell lines (MCF-7) reveals that H2L has negligible toxicity in low concentration levels and can be effectively used for live cell imaging.

A new fluorogenic probe, COUBM (where, COUBM = 3-(1H-benzoimidazol-2-yl)-8-benzothiazol-2-yl-chromen-2-ylideneamine) is designed and synthesized for selective and rapid detection of phosgene both in solution and gas phase. COUBM reacts with phosgene to form a cyclic carbamylated product (COUBM-PHOS) and consequently a sharp increase in fluorescence intensity is observed. The probe is efficiently used to detect phosgene in vapor phase using the COUBM loaded filter paper kit. Theoretical calculation by DFT/B3LYP/6−31+G(d) method is performed to interpret the electronic structure and the probable sensing mechanism of the probe for the detection of phosgene.

Herein we report the selective detection of Cu2+ and SO3 2− by phenanthraquinone thiosemicarbazone (PQTSC) chemosensor. The chemosensor is efficient in detecting Cu2+ over other metal ions, while the PQTSC-Cu2+ complex selectively sense SO3 2− over other anions. On addition of Cu2+ to the receptor solution, quenching of emission intensity is observed by 16 folds and upon gradual addition of SO3 2− to this solution, the emission intensity increases and the maxima is regained. The limit of detection for Cu2+ detection calculated from fluorescence titration is 1.06 × 10−8 M and the association constant of PQTSC with Cu2+ is found to be 2.18 × 105.

A highly sensitive and selective pyridyl based colorimetric chemosensor (H2L) for the efficient detection of Ni(2+) has been reported. The synthesized chemosensor H2L is highly efficient in detecting Ni(2+) even in the presence of other metal ions that commonly co-exist with Ni(2+). H2L also shows distinct color change from green to deep red visible under naked eye due to specific binding with Ni(2+). This color change is due to formation of a new band at 510 nm upon gradual addition of Ni(2+). The association constant has been found to be 1.27×10(5) M(-1) with limit of detection (LOD) of 8.3×10(-7) M. Electronic structure of the H2L-Ni(2+) complex and sensing mechanism have been interpreted theoretically by DFT and TDDFT calculations.

A new coumarin based fluorescent switch (HCBP) has been fabricated which displays high selective sensing towards Al3+ among other metal cations at physiological pH. On gradual addition of Al3+ specifically, HCBP shows a brilliant “turn-on” emission enhancement of about ∼13-fold with about 50 nm red shift at 481 nm in MeOH/H2O (1/1, v/v) solution. The fluorescent switch is proven to be a reversible probe by addition of EDTA gradually into the HCBP-Al3+ solution. Detection limit as well as Binding constant values have been calculated and found to be in the order of 10−9 M and 103 M-1 respectively. DFT and TDDFT studies are conducted with the probe to establish a similarity between theoretical and experimental outcomes. We can also use this new fluorescent switch as a biomarker kit as it has shown a brilliant potential in the application of live cell imaging using gastric cancer cell (AGS cell).

Herein, we have designed and synthesized an effective fluorogenic chemosensor, BTCP for the sensing of DCP, a very low toxic simulant of sarin both in the vapour and solution phases. The poor emission property (λmax = 470 nm, quantum yield (φ) = 0.051) of BTCP is significantly increased in the presence of DCP with a red shift of the emission wavelength (λmax = 542 nm, quantum yield (φ) = 0.241) in CH3CN/H2O (1/1, v/v, pH = 7.2) medium. The limit of detection is found to be as low as 15.8 nM for the detection of DCP. Moreover, the fluorescent probe (BTCP) is very useful for the visualization of DCP within human lung cancer cell lines (A549). Sensing of the probe is based on the formation of a new adduct, BTCP-DCP and inhibition of photo-induced electron transfer (PET) process present in the free BTCP. The structure of the probe (BTCP) is confirmed by single crystal X-ray crystallography. Density functional theory (DFT) and time dependent density functional theory (TDDFT) computational techniques are used to interpret the electronic structure and Uv–vis spectra of both BTCP and BTCP-DCP adduct.

Department of Chemistry, Jadavpur University, Kolkata-700 032, India E-mail : tkmondal@chemistry.jdvu.ac.in Manuscript received 02 May 2017, accepted 08 May 2017 A new azo-phenol based chemosensor has been designed, synthesized and its structure is confirmed through different spectroscopic techniques. The synthesized chemosensor (HL) has shown a marked colorimetric response from light yellow to purple upon complexation with Cu2+ which is easily detectable through naked eyes, makes the sensor efficient one to detect Cu2+ and remain nonresponsive in presence of other competitive metal ions. The 1 : 1 complex formation of HL with Cu2+ is determined from Job’s plot analysis and mass spectroscopic studies. Association constant (Ka, 8.94×104 M–1) of HL-Cu2+ complex suggests HL has high affinity towards Cu2+.

A potent fluorescence 'turn-on' receptor (HL) based on rhodamine and coumarin moieties for the detection of Hg

New biphenyl derivatives of bis-imidazoline selones were synthesized in good yield and characterized by multinuclear (1D and 2D) NMR and UV-vis studies. The solid state structures of bis-imidazoline selones were further confirmed by single crystal X ray diffraction technique.

Herein we report the selective detection of Cu