A dual analyte fluorescent chemosensor based on a furan-pyrene conjugate for Al3+ & HSO3. Spectrochim Acta A Mol Biomol Spectrosc 2017;174:62-69. [PMID: 27888783 DOI: 10.1016/j.saa.2016.11.021]

A bis-chalcone based colorimetric probe for the selective detection of bisulfite/sulfite anions: exploring surfactant promoted Michael addition of anions to α, β-unsaturated ketones

A probe, (1E,4E)-1,5-di(thiophen-2-yl)penta-1,4-dien-3-one, was developed for rapid, colorimetric, and selective detection of bisulfite/sulfite anions in aqueous solutions. This probe is based on the Michael addition reaction which is favoured in the presence of cationic micellar medium CTAB. CTAB promoted Michael addition is an effective tool to determine SO₂ toxicity, which is mainly expressed in terms of collective concentration of bisulfite and sulfite anions. The probe showed high selectivity and sensitivity toward bisulfite and sulfite over other interfering anions, with a detection limit of 0.43 μM and 0.23 μM, respectively. The possible recognition mechanism of the probe and the analyte was illustrated by NMR, HR-MS, IR, and computational analysis. Moreover, this probe showed great potential for the detection of bisulfite/sulfite in real samples, such as crystal sugar and brown sugar.

R. B, M. M, Iqbal M, Shivamallu C, Amachawadi RG, Kollur SP. Highly selective and sensitive fluorescent “TURN-ON” furan-based Schiff base for zinc(ii) ion probing: chemical synthesis, DFT studies, and X-ray crystal structure

A simple and efficient fluorescent probe (E)-4-bromo-2-((((5-methylfuran-2-yl)methyl)imino)methyl)phenol (BFMP) for the detection of Zn2+ ions was synthesized by the condensation of 5-methyl-furfurylamine and 5-bromosalicylaldehyde.

A simple "turn-on" fluorescent sensor for reversible recognition of aluminum ion in living cell

A simple and reliable "turn-on" fluorescent sensor (E)-1-[((2-hydroxyethyl)imino) methyl] naphthalen-2-ol (HNP) has been designed, synthesized, and characterized by ¹H-NMR, ¹³C-NMR, FT-IR, and EI-MS analysis. The binding property of HNP was examined employing UV-Vis and fluorescence spectroscopy. HNP exhibited high selectivity towards Al³⁺ among other cations and anions. The fluorescence titration experiment has established binding stoichiometry of HNP with Al³⁺ is 2:1, which can be further verified by HR-MS. The detection limit of HNP is 2.9 μM, and it can be reversible five-to-seven times to detect Al³⁺ without losing much efficiency which indicates that it can be a reliable probe for Al³⁺. Additionally, HNP was successfully applied for the detection of Al³⁺ in living cells. To achieve the detection of aluminum ion across a simple, reliable, and precise method, we have investigated the reversible detection (which can reversible response to Al³⁺ for five-to-seven times) of Al³⁺ through an extremely simple (requires only one-step reaction) "turn-on" fluorescent probe which enables us to visualize and analyze Al³⁺ with low detection limit (2.9 μM) and high selectivity in living cell without interference from the high abundant small biological molecules.

Synthesis, Computational and cytotoxicity studies of aryl hydrazones of β-diketones: Selective Ni2+ metal Responsive fluorescent chemosensors

A new fluorescent sensor 2-(2-(3-chloro-4-fluorophenyl)hydrazono)-5,5-dimethyl cyclohexane-1,3-dione (A) and 2-(2-(4-chloro-2-nitrophenyl)hydrazono)-5,5-dimethyl cyclohexane-1,3-dione (B) composed of a β-diketones of aryl hydrazones synthesized by simple and cost-effective method. Various analytical tools analyzed the structural investigations of the synthesized substituted β-diketones of aryl hydrazones like FT-IR, ¹H, ¹³C NMR and UV-Vis techniques, Single-crystal X-ray diffraction studies (SCXRD) (for A), Scanning electron microscopy (SEM), and fluorescence spectroscopy. SEM also investigates surface morphology modifications of aryl hydrazones and Ni²⁺ complex. Furthermore, the metal sensing (Chemo sensing) behavior of newly prepared aryl hydrazones of β-diketones derivatives was further studied by fluorescence spectroscopy. The aryl hydrazones sensor materials show admirable fluorescence selectivity with enrichment to Ni²⁺ over different cations in an aqueous ethanol solution with a recognition extremity of 4 μM-7 μM. A joint experimental and theoretical investigation was led on the chemical structure employing a density functional theory (DFT) (B3LYP), engaging a 6-31G basis set. The DFT technique's enhanced geometrical bond angles and lengths exhibited great covenant with the experimental results. The highest occupied molecular (HOMO) orbital and lowest unoccupied (LUMO) molecular orbital energy has been concluded. The cytotoxicity studies show these compounds impede the growth of KB cells highly and from the studies to evaluate their capability to accurately dock aryl hydrazones to antibodies of cancer protein such as 4LRH, 4L9K, 4 EKD and 4GIW cancer proteins.

Sensitive fluorescent chemosensor for Hg(II) in aqueous solution using 4'-dimethylaminochalcone

Mercury (Hg) is an element with high toxicity, especially to the nervous system, and fluorescent pigments are used to visualize dynamic processes in living cells. A little explored fluorescent core is chalcone. Herein, we synthesized chalcone (2E)-3-(4-(dimethylamino)phenyl)-1-phenylprop-2-en-1-one (8) and assessed its photophysical properties. Moreover, the application of this chemosensor in aqueous media shows a selective fluorescence quenching effect with Hg(II). The figures of merit for the chemosensor were calculated to be LOD = 136 nM and LOQ = 454 nM, as well as a stoichiometry of 1:1. Furthermore, the association constant (K_a) and fluorescence quenching constant (K_SV) were calculated using the Benesi-Hildebrand and Stern-Volmer equations to be K_a= 9.08 × 10⁴ and K_SV= 1.60 × 10⁵, respectively. Finally, by using a computational approach, we explain the interaction between chalcone (8) and Hg(II) and propose a potential quenching mechanism based on the blocking of photoinduced electron transfer.

A photoswitchable "turn-on" fluorescent chemosensor: Quinoline-naphthalene duo for nanomolar detection of aluminum and bisulfite ions and its multifarious applications

A quinoline-naphthalene duo-based Schiff base probe (R) was synthesized and characterized by the usual spectroscopic and single-crystal X-ray crystallographic techniques. Probe R detects Al³⁺ and HSO₃^- ions via the fluorescent turn-on approach by dual pathways i.e., i) when probe R interacts with Al³⁺, the restriction of CN single bond rotation, blocking of both photoinduced electron transfer (PET) and CN isomerization were observed, and ii) when the sensor R interacts with HSO₃^-, imine (CH = N) bond was cleaved via hydrolysis and produced the respective aldehyde and amine behaving as a chemodosimeter. The binding stoichiometric ratio of R + Al³⁺ (1:1) was confirmed by Job's plot, emission titration profile, NMR, and mass spectrometric analyses. This probe R is highly selective to both Al³⁺ -ions and HSO₃^- -ions, without any interference of other potentially competing cations and anions. Limit of detection (LOD) and quantification (LOQ) of R with Al³⁺ and HSO₃^- were downed to nanomolar concentrations, which is much lower than the recommended level of drinking water/food fixed by the World Health Organization (WHO). Furthermore, probe R was utilized in the detection of Al³⁺ and HSO₃^- ions in highly contaminated real samples, bioimaging in E. coli cells, multiple-targeting molecular logic gate, and in bovine serum albumin (BSA) binding.

Triphenyl-imidazole based reversible coloro/fluorimetric sensing and electrochemical removal of Cu2+ ions using capacitive deionization and molecular logic gates

A simple hydroxyl-substituted triphenyl-imidazole based receptor (HTPI) which selectively detects Cu²⁺ ion by colorimetric and fluorimetric methods was developed. HTPI detects the Cu²⁺ ions with the absorption enhancement and fluorescence quenching by the possible ligand to metal charge transfer (LMCT) and the chelation-enhanced quenching (CHEQ) approaches, respectively. HTPI showed high selectivity and sensitivity for Cu²⁺ ions detection over other interfering and competing metal ions. Interestingly, HTPI detects Cu²⁺ ion (LOD) at nanomolar concentrations (19 × 10^-9 M (UV-vis) & 27 × 10^-9 M (fluorescence), respectively), which is lower than the permissible level of Cu²⁺ ion reported by World Health Organization (WHO). Furthermore, HTPI was applied to the molecular logic gate function by using chemical inputs, and Cu²⁺ ion was potentially removed (95%) via Capacitive Deionization technique.

A ratiometric fluorescent probe for the rapid and specific detection of HSO3 - in water samples

Hydrosulphite (HSO₃ ^- ), as a common and important chemical reagent, is widely used in everyday life, however excessive use and abuse of HSO₃ ^- can cause potential harmful effects on the environment and in biological health. In this paper, we describe the design and preparation of a colorimetric and ratiometric fluorescence probe for the visual detection of HSO₃ ^- (excitation wavelengths were, respectively, 336 nm and 520 nm). This method showed some advantages including simple preparation, high selectivity, fast response, and significant colour and fluorescence ratio (F₄₅₀ /F₅₉₄ ) changes in the presence of HSO₃ ^- . In addition, this probe was used successfully for the detection of HSO₃ ^- in real water samples and showed a good recovery rate range.

Application of real sample analysis and biosensing: Synthesis of new naphthyl derived chemosensor for detection of Al3+ ions

A new chemosensor (NANH) based on naphthyl moiety was synthesized with good selectivity and sensitivity towards Al³⁺ ions via the inhibition by operating through dual mechanisms like photo-induced electron transfer (PET) and excited-state intramolecular proton transfer (ESIPT). The synthesized NANH was validated by various techniques such as ¹H, ¹³C NMR and mass spectrum. While prominent fluorescent enhancement was observed from the NANH upon binding with Al³⁺ ions, however, other metal ions have not responded in the emission spectrum. Detection limit and association constant of NANH for Al³⁺ were calculated as 1.2 × 10^-7 M and 4.09 × 10⁴ M^-1 by using fluorescence titration method. Binding ratio (1:1) of NANH with Al³⁺ ions were proved by Job's plot and DFT studies. Furthermore, aluminium in variety of water samples was determined, and NANH could be used for biosensing of Al³⁺ in living cells.

A novel phenolphthalein-based fluorescent sensor for Al3+ sensing in drinking water and herbal tea samples

In this study, 3,3-bis(4-hydroxy-3-((E)-((4-hydroxyphenyl)imino)methyl) phenyl)isobenzofuran-1(3H)-one (HMBP) was designed as a ''turn-on″ fluorogenic chemosensor to detect Al³⁺. Studies were performed in C₂H₅OH-HEPES (v/v, 9/1, pH 7.0) media at λ_em = 475 nm. The LOD value was found to be 0.113 µM. The stoichiometric ratio of HMBP-Al³⁺ was determined as 1:2 by Job's plot and ESI-MS as well as ¹H NMR titration. The binding constant of chemosensor HMBP with Al³⁺ from the Benesi-Hildebrand equation was determined to be 1.21 × 10⁸ M^-1. The quantum (Φ) yields were obtained as 0.040 and 0.775 for the chemosensor HMBP and HMBP-Al³⁺, respectively. The response of the chemosensor HMBP towards Al³⁺ was attributed to the strategies of blocking the photo-induced electron transfer (PET) and CN isomerisation mechanisms. Finally, the sensing of the chemosensor HMBP for the determination of Al³⁺ in real food samples, drinking waters and herbal teas, were employed.

Experimental and Theoretical Studies on a Simple S-S-Bridged Dimeric Schiff Base: Selective Chromo-Fluorogenic Chemosensor for Nanomolar Detection of Fe2+ & Al3+ Ions and Its Varied Applications

A simple S-S (disulfide)-bridged dimeric Schiff base probe, L, has been designed, synthesized, and successfully characterized for the specific recognition of Al3+ and Fe2+ ions as fluorometric and colorimetric "turn-on" responses in a dimethylformamide (DMF)-H2O solvent mixture, respectively. The probe L and each metal ion bind through a 1:1 complex stoichiometry, and the plausible sensing mechanism is proposed based on the inhibition of the photoinduced electron transfer process (PET). The reversible chemosensor L showed high sensitivity toward Al3+ and Fe2+ ions, which was analyzed by fluorescence and UV-vis spectroscopy techniques up to nanomolar detection limits, 38.26 × 10-9 and 17.54 × 10-9 M, respectively. These experimental details were advocated by density functional theory (DFT) calculations. The practical utility of the chemosensor L was further demonstrated in electrochemical sensing, in vitro antimicrobial activity, molecular logic gate function, and quantification of the trace amount of Al3+ and Fe2+ ions in real water samples.

Imaging endogenous HClO in atherosclerosis using a novel fast-response fluorescence probe

A novel probe S-ClO was developed, which could selectively sense HClO as well as monitor HClO-induced arterial vessel inflammation.

A chemosensor with a paddle structure based on a BODIPY chromophore for sequential recognition of Cu2+ and HSO3−

In this study, a highly selective chemosensor ML based on a BODIPY fluorescent chromophore was synthesized for sequential recognition of Cu²⁺ and HSO₃⁻ in a CH₃OH/H₂O (99 : 1 v/v) system, which contained three recognition sites and its structure characterized by ¹H NMR, ¹³C NMR and ESI-HR-MS. The sensor ML showed an obvious “on–off” fluorescence quenching response toward Cu²⁺ and the ML-Cu²⁺ complex showed an “off–on” fluorescence enhancement response toward HSO₃⁻. The detection limit of the sensor ML was 0.36 μM to Cu²⁺ and 1.4 μM to HSO₃⁻. In addition, the sensor ML showed a 1 : 3 binding stoichiometry to Cu²⁺ and the recovery rate of ML-Cu²⁺ complex identifying HSO₃⁻ could be over 70%. Sensor ML showed remarkable detection ability in a pH range of 4–8.

A highly selective chemosensor based on a BODIPY chromophore for sequential recognition of Cu²⁺ and HSO₃⁻.

A naphthalene-quinoline based chemosensor for fluorescent "turn-on" and absorbance-ratiometric detection of Al3+ and its application in cells imaging

A new naphthalene-quinoline based chemosensor L was prepared and structurally characterized. L exhibited excellent selectivity and sensitivity to Al³⁺ through distinct fluorescence enhancement (335-fold) and ratiometric detection in DMF/H₂O (v/v, 1/9) based on the combined mechanisms of ESIPT and CHEF. The recognizing behavior of L toward Al³⁺ had been investigated in detail through Job's Plot, FT-IR, HNMR, and HRMS analysis. The limit of detection (LOD) for Al³⁺ was as low as and 3.67 × 10^-8 M. L was successfully applied in real sample detection and construction of molecular logic gate. Moreover, L was verified to be of low cytotoxicity and good imaging characteristics for the detection of Al³⁺ in cells HSC.