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• Interplay of ESIPT, ICT and AIEE phenomena on single platform was observed. • Mixed aqueous medium was used for the sensing of F − and P2O74− ions. • The lowest detection limits for F − and P2O74− ions were calculated to be 41 nM and 23 nM. • Aggregation-disaggregation process of probe 1 and probe 1 + F −/P2O74− ions was investigated. In this study, the Schiff base (probe 1) was designed and synthesized, using the moieties of benzothiazole and salicylaldehyde as signaling units. UV–visible and emission spectroscopy has been identified to study interaction of probe 1 with various anions. Absorption bands at 290 and 360 nm for probe 1 (20 µM; CH 3 CN) were observed and two fluorescence peaks at 415 and 540 nm obtained with excitation at 360 nm in CH 3 CN. Probe 1 (20 µM) developed a yellow color in presence of F − and P 2 O 7 4− ions in their tetrabutylammonium salts. For both the ions, the corresponding absorption measurements revealed bathochromic shift of 85 nm. When complexed with anions, emission changes show that probe 1 acts as a " turn-on " sensor. Probe 1 shows detection limit (LOD) of 35.4 and 15.4 nM for F − and P 2 O 7 4−, respectively. 1H NMR titration analyses revealed more about their mode of binding with probe 1. [Display omitted] [ABSTRACT FROM AUTHOR]

We report the syntheses and structural characterization of a Zn(II) metallacycle [Zn2{(L)2(DMF)2(NO3)2}]·(NO3)2 (1) along with a Cd(II) coordination polymer [{Cd1(L)2(DMF)2}·(NO3)2]n (2) (where L = N,N′-bis-(3-pyridyl)terephthalamide; DMF = dimethylformamide) and their utilization as fluorescent probes for highly selective recognition (turn-off) of Fe3+ and CrO42− ions. Compounds 1 and 2 were prepared by utilizing ligand L and the nitrate salt of zinc and cadmium, respectively. Single crystal X-ray analysis reveals that 1 adopts an overall Zn(II) metallacycle architecture, whereas 2 displays a one-dimensional (1D) polymeric structure. Both 1 and 2 showed high fluorescence stability in aqueous solution and selectively detected Fe3+ and CrO42− ions with high quenching constants and low detection limits of 2.34 × 106 M−1 and 0.153 μM for Fe3+, 6.72 × 105 and 0.205 μM for CrO42− (for 1); 3.25 × 106 and 0.193 μM for Fe3+, 6.94 × 105 and 0.155 μM for CrO42− (for 2). Notably, ligand L itself did not display any type of recognition for any ions in DMF as well as in aqueous media. Moreover, 1 and 2 were also employed as heterogeneous catalysts for the ring-opening reaction (ROR) of epoxides with various assorted amines and up to 95% yield (TON, 47.5 and TOF, 11.9 h−1) was observed with perfect regioselectivity in the case of styrene oxide. [ABSTRACT FROM AUTHOR]

We present two ZnII‐ and CdII‐based coordination polymers (CPs), L‐Zn and L‐Cd, offering H‐bonding‐based cavities of varying dimensions. Both CPs were used for the highly selective detection of S2O72− and Fe3+ ions where H‐bonding based cavities played an important role. Fluorescence quenching, competitive binding studies and binding parameters substantiated significant recognition of S2O72− and Fe3+ ions by both CPs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesized probe 1 shows ICT phenomenon. • Probe 1 could detect Al3+ and HSO 4 - ions in mixed solvent medium H 2 O: CH 3 OH (1:1 [v/v]) with lowest detection limit of 39 nM and 23 nM respectively. • Probe 1 can be utilized for the construction of a molecular keypad lock. • Probe 1 can be used for quantitative determination of HSO 4 - ion in different real field water samples. Dual hydrogen bonded Schiff base containing unsymmetrical double proton transfer sites, one with imine bond (C N) and hydroxyl group (OH), and the other with benzimidazole and hydroxyl groups has been successfully synthesized. Probe 1 displayed intramolecular charge transfer and acts as a potential sensor for Al3+ and HSO 4 - ions. Probe 1 displayed two absorption peaks at 325 nm and 340 nm and an emission band at 435 nm upon excitation at 340 nm. Probe 1 behaves as a fluorescence " turn-on " chemosensor for both Al3+ and HSO 4 - ions in H 2 O-CH 3 OH solvent system. The proposed method allows the determination of Al3+ and HSO 4 - ions up to 39 nM and 23 nM at emission wavelength 385 nm and 390 nm, respectively. The binding behavior of probe 1 towards these ions is determined by the Job's plot method and 1H NMR titrations. Probe 1 is used to construct a molecular keypad lock where the absorbance channel can be opened only in the presence of the correct sequence. Further, it is used for the quantitative determination of HSO 4 - ion in different real-field water samples. [ABSTRACT FROM AUTHOR]

[Display omitted] • Interplay of AIE and ESIPT phenomenon on a single molecular platform. • Detects Pb2+ and Al3+ ions in a mixed aqueous medium having LOD of 2.7 nM and 33 nM, respectively. • Detection of Pb2+ in real water samples. • Probe 1 could be utilized as AND, OR, and NOT molecular logic gates. Dual ESIPT efficient Schiff-base probe possessing multiple binding sites was synthesized which is capable of showing Aggregation Induced Emission (AIE) properties. Probe 1 behaves as a fluorescence "turn-on" chemosensor, showing interactions with Pb2+ and Al3+ ions in H 2 O-CH 3 CN solvent at pH≈7. The binding constant and detection limit for all the ions were calculated. The binding properties of probe 1 with all the ions were checked by Job's plot and the 1H NMR titration method. Further, the presence of dual intramolecular hydrogen bonding was confirmed theoretically by geometrical parameters and FTIR analysis. The potential energy curves (PECs) calculations for proton transfer coordinates verified that probe 1 shows a single ESIPT process. Thus with good selectivity and sensitivity and fast response time, a highly efficient platform for simultaneous detection of Pb2+ ions was generated using a simple molecule. [ABSTRACT FROM AUTHOR]

• Synthesis of a novel chromo-fluorescent naphthalimide based probe 1. • Probe 1 exhibited dual emission at 510 nm and 610 nm due to ESIPT/ESICT phenomenon. • Probe 1 detects Al3+ ions ratiometrically via inhibition of ESIPT/ESICT. • Probe 1 detects F− ions ratiometrically with colour change orange to purple. An optical probe 1 has been synthesized comprising naphthalimide unit conjugated with Schiff base, exhibiting excited state intramolecular proton transfer and intramolecular charge transfer as a potential sensor for Al3+ and F− ions using standard spectroscopic techniques. The probe 1 exhibited local and charge-transfer excitation at 340 nm and 460 nm, respectively. On excitation at 460 nm, probe 1 displayed two emission bands at 510 nm and 610 nm, accompanied by Stokes' shift of 50 nm and 150 nm, respectively. The solvatochromic effect and theoretical calculation depicted that the representative emissions resulted from the ESICT/ESIPT phenomenon. Upon addition of Al3+ ions, the charge transfer excitation at 460 nm was enhanced ratiometrically to local excitation at 340 nm and showed a color change from orange to yellow. Similarily, probe 1.Al3+ displayed emission enhancement at 540 nm in H 2 O/CH 3 CN (1:9; v/v) and showed a color change from yellow to blue-green emission. Following the detection of Al3+ ions, hydrolysis of probe 1 to its reacting precursors was observed. The detection of Al3+ ions was also demonstrated in surfactant-containing water. The limit of detection (LOD) of probe 1 (H 2 O/CH 3 CN (1:9; v/v)) towards Al3+ ions was measured to be 3.2 × 10−8 M. The probe 1 displayed a ratiometric absorption response towards F− ions with a new peak at 570 nm and showed a color change from orange to purple. The probe 1.F− displayed a decrease in emission at 635 nm. The LOD of probe 1 (CH 3 CN) towards F− ions was measured to be 7.5 × 10−7 M. [ABSTRACT FROM AUTHOR]