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In this work, a novel organic receptor, CPI [(E)-3-(4-(9H-carbazol-9-yl)phenyl)-2-(1H-benzo[d]imidazol-2-yl)acrylonitrile], was rationally designed and successfully fabricated for selective and sole recognition of CN− ions over other competitive anions through an obvious chromogenic and ratiometric emission change in DMSO. The distinct and prominent color change upon the addition of CN− can be attributed to the typical ICT process, which is induced by the deprotonation of acidic NH protons in the imidazole moiety. The sensor displayed strong solvatochromic effects in commonly used organic solvents such as n-hexane, toluene, diethyl ether, DCM, THF, DMF and DMSO. The chemical structure of the sensor was characterized by single-crystal X-ray diffraction, 1HNMR, 13CNMR, IR and mass spectroscopy. Significantly, the probe can function as a fluorescence-based sensor for the efficient detection of low-level water in organic solvents. The solid-state emission properties of CPI were successfully applied to recognise cyanide in a solid-state platform with naked eye-visualized distinct color change. The probe can be made reusable by adding TFA into the CN− treated probe solution. The detection limit of CPI towards CN− was determined to be 4.48 × 10−8 M. More importantly, the sensor is capable of detecting CN− in food samples and has been employed for wastewater treatment. Besides, easy-to-prepare CPI-coated test strips provide a simple, reusable and easy-to-handle protocol for the qualitative identification of CN− conveniently. Finally, density functional theory and time-dependent density functional theory were performed to verify the experimental outcomes theoretically. [ABSTRACT FROM AUTHOR]

A new coumarin based fluorescent switch PCEH is fabricated which displays high selective sensing towards Al3+ among other metal cations at physiological pH. On gradual addition of Al3+, PCEH shows a brilliant "turn-on" emission enhancement in MeOH/H2O (4/1, v/v) solution. This new fluorescent switch is proven to be a reversible probe by gradual addition of F− into the PCEH-Al3+ solution. Detection limit as well as binding constant values are calculated to be in the order of 10–9 M and 104 M−1 respectively. We have also explored its potential as a biomarker in the application of live cell imaging using breast cancer cells (MDA-MB-231 cell). [ABSTRACT FROM AUTHOR]

Fluorescent chemosensor detecting a widely used but highly toxic chemical warfare agent (CWA) such as phosgene is of great importance due to its high sensitivity along with low cost and simple method of preparation. In this study a biphenyl-benzoimidazole based (BPCI) chemodosimeter, which displayed a rapid, sensitive and ratiometric detection of the lethal pulmonary agent phosgene, has been developed. Upon the addition of phosgene to the BPCI solution in THF, we observed a fluorescence color change from blue to cyan-green. The chemodosimeter (BPCI) undergoes nucleophilic substitution reaction with phosgene followed by ring closure to yield the carbamylated final product and shows an explicit ratiometric fluorescence response towards phosgene. The carbamylation was accelerated due to the formation of a six-member ring, which restricts the C–C bond rotation. The probe (BPCI) selectively detected phosgene over other toxic relevant analytes. The detection limit (LOD) of BPCI for phosgene was established to be in the order of 10−7 M in the solution phase, which implied that BPCI can detect phosgene at a very minuscule level. This ratiometric switch, which we developed, can be used as a potential portable kit for detecting phosgene in the vapour phase, as well as in the solid phase when supported upon TLC plates. Theoretical calculations using the DFT/B3LYP/6-31+G(d) method were performed to unveil the electronic properties theoretically and to interpret the probable sensing mechanism. [ABSTRACT FROM AUTHOR]

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 a higher selectivity than that of others anions such as Br−, Cl−, I−, NO3−, SO42−, SCN−, CO32−, N3−, OH−, HCO3−, H2PO4−, HPO42−, F−, ACO−, and PO43− in a DMSO : H2O medium (40 : 60, v/v, HEPES buffer, pH = 7.2). The "turn off" fluorescence response mechanism can be attributed to the intra-molecular charge transfer (ICT) process, which is blocked by the nucleophilic attack of cyanide ions at the cyano vinyl group of the probe. The LOD was found to be 3.57 × 10−8 M. The interaction involved behind the sensing of cyanide was investigated by Job's plot analysis, 1H-NMR, and mass spectroscopic studies. DFT and TDDFT were also employed to verify the experimental outcomes. Moreover, the test strip experiment provides a wide application prospect of the receptor for detecting poisonous cyanide in the environment and biological system. [ABSTRACT FROM AUTHOR]

A highly sensitive, reversible, reusable and fluorogenic "turn-on" probe (HBTC) is fabricated for the sole detection of Al3+. On incremental addition of Al3+ in a solution of HBTC in ACN : H2O (4 : 1), a sharp "turn-on" emission enhancement is observed at 480 nm. The reversibility of the probe (HBTC) was displayed on the addition of F− solution. The detection limit is found to be of the order of 10−9 M which suggests that HBTC can detect Al3+ at a very minute level. The mechanism for Al3+ detection in ACN : H2O (4 : 1) is attributed to forbidding C＝N isomerization and ESIPT process simultaneously turning on the chelation-enhanced fluorescence process. The reusability and real-time application of the probe are also studied. Bioimaging study reveals that HBTC can detect Al3+ in human breast cancer cells (MDA-MB-231). Electronic structure of the probe is explained by density functional theory. [ABSTRACT FROM AUTHOR]

A new chromone-based fluorescent probe (HMPM) is introduced for the selective detection of Pd2+. The designed probe exhibits a ratiometric fluorescence enhancement, which can be attributed to the ESIPT and/or chelation enhancement fluorescence (CHEF) processes. HMPM is efficient enough to detect Pd2+ solely in the presence of other metal ions in DMSO/H2O solution (1 : 1, v/v, pH = 7.2) with a limit of detection as low as 2.9 nM. Furthermore, the complex formation of HMPM with Pd2+ is confirmed by the single crystal X-ray diffraction method. The changes in electronic structure and absorption spectrum of HMPM upon complexation with Pd2+ are supported by DFT and TDDFT calculations. Moreover, the probe (HMPM) could be effectively used for the detection of Pd2+ by a dip-stick method. [ABSTRACT FROM AUTHOR]

A new chromone-based fluorescent probe (HMPM) is introduced for the selective detection of Pd2+. The designed probe exhibits a ratiometric fluorescence enhancement, which can be attributed to the ESIPT and/or chelation enhancement fluorescence (CHEF) processes. HMPM is efficient enough to detect Pd2+ solely in the presence of other metal ions in DMSO/H2O solution (1 : 1, v/v, pH = 7.2) with a limit of detection as low as 2.9 nM. Furthermore, the complex formation of HMPM with Pd2+ is confirmed by the single crystal X-ray diffraction method. The changes in electronic structure and absorption spectrum of HMPM upon complexation with Pd2+ are supported by DFT and TDDFT calculations. Moreover, the probe (HMPM) could be effectively used for the detection of Pd2+ by a dip-stick method. [ABSTRACT FROM AUTHOR]

New Pd(II) and Pt(II) complexes, [Pd(HL)Cl2] (C1) and [Pt(L)Cl] (C2) with ONN donor pincer ligand, 5-(diethylamino)-2-((Z)-((E)-(phenyl(pyridin-2-yl)methylene)hydrazono)methyl)phenol (HL) were synthesized and thoroughly characterized using spectroscopic techniques. X-ray structures of the complexes revealed that HL acts as bidentate N,N and tridentate O,N,N chelator in Pd(II) and Pt(II) complexes, respectively. The antiproliferative activity of the complexes was explored against four different human cancer (MCF-7, HCT116, A549, HepG2) cell lines. However, the maximum cytotoxicity was seen in the HepG2 cell line [IC50 = 6–12 μM] for both the complexes. IC50 for both complexes, C1 and C2, toward human peripheral blood mononuclear cells (hPBMC) cells were found to be >200 μM. The cytotoxicity of platinum complex (C2) was comparable to that of the cisplatin in HepG2 cell lines. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this paper, two new quinoline‐benzothiazole based probes (QBTP1 and QBTP2) have been synthsized for the selective detection of Cd2+. Both the probes showed selective 'Turn‐On' emission change towards Cd2+. Structure of QBTP1 was confirmed through its single crystal X‐ray study. QBTP1 itself showed a weak emission band at 488 nm which upon addition of Cd2+ enhanced dramatically with a slight redshift to 507 nm. Consequently, weak cyan emission of QBTP1 changes to green which is easily observable through naked eyes. QBTP2 also showed almost similar fluorescence change upon addition of Cd2+ to that of QBTP1. The intramolecular charge tranfer (ICT) and chelation enhanced fluorescence (CHEF) mechanisms may play here the key role for this type of redshift of emission maximum and enhancement of fluorescence intensity respectively, upon addition of Cd2+ to the probes. Both the probes exclusively detecs Cd2+ over any other cations tested. Most importantly, not a minute interference was observed by Zn2+ or Hg2+. Capabilities of the probes to be used as portable kits for on‐site detection of Cd2+ without using any expensive instrumental help was also shown here. Furthermore, the limit of detection of both the probes were found in the order of 10−9 to 10−10 M range which indicates the high sensitivity of the probes towards Cd2+. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 C=N 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). [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In this work, a novel organic receptor, CPI [(E)-3-(4-(9H-carbazol-9-yl)phenyl)-2-(1H-benzo[d]imidazol-2-yl)acrylonitrile], was rationally designed and successfully fabricated for selective and sole recognition of CN− ions over other competitive anions through an obvious chromogenic and ratiometric emission change in DMSO. The distinct and prominent color change upon the addition of CN− can be attributed to the typical ICT process, which is induced by the deprotonation of acidic NH protons in the imidazole moiety. The sensor displayed strong solvatochromic effects in commonly used organic solvents such as n-hexane, toluene, diethyl ether, DCM, THF, DMF and DMSO. The chemical structure of the sensor was characterized by single-crystal X-ray diffraction, 1HNMR, 13CNMR, IR and mass spectroscopy. Significantly, the probe can function as a fluorescence-based sensor for the efficient detection of low-level water in organic solvents. The solid-state emission properties of CPI were successfully applied to recognise cyanide in a solid-state platform with naked eye-visualized distinct color change. The probe can be made reusable by adding TFA into the CN− treated probe solution. The detection limit of CPI towards CN− was determined to be 4.48 × 10−8 M. More importantly, the sensor is capable of detecting CN− in food samples and has been employed for wastewater treatment. Besides, easy-to-prepare CPI-coated test strips provide a simple, reusable and easy-to-handle protocol for the qualitative identification of CN− conveniently. Finally, density functional theory and time-dependent density functional theory were performed to verify the experimental outcomes theoretically. [ABSTRACT FROM AUTHOR]

In this paper, two new quinoline‐benzothiazole based probes (QBTP1 and QBTP2) have been synthsized for the selective detection of Cd2+. Both the probes showed selective 'Turn‐On' emission change towards Cd2+. Structure of QBTP1 was confirmed through its single crystal X‐ray study. QBTP1 itself showed a weak emission band at 488 nm which upon addition of Cd2+ enhanced dramatically with a slight redshift to 507 nm. Consequently, weak cyan emission of QBTP1 changes to green which is easily observable through naked eyes. QBTP2 also showed almost similar fluorescence change upon addition of Cd2+ to that of QBTP1. The intramolecular charge tranfer (ICT) and chelation enhanced fluorescence (CHEF) mechanisms may play here the key role for this type of redshift of emission maximum and enhancement of fluorescence intensity respectively, upon addition of Cd2+ to the probes. Both the probes exclusively detecs Cd2+ over any other cations tested. Most importantly, not a minute interference was observed by Zn2+ or Hg2+. Capabilities of the probes to be used as portable kits for on‐site detection of Cd2+ without using any expensive instrumental help was also shown here. Furthermore, the limit of detection of both the probes were found in the order of 10−9 to 10−10 M range which indicates the high sensitivity of the probes towards Cd2+. [ABSTRACT FROM AUTHOR]