Cu/CuxOy NPs architectured COF: a recyclable catalyst for the synthesis of oxazolidinedione via atmospheric cyclizative CO2 utilization.

The present study describes the favourable construction of a crystalline covalent organic framework (COF) with exceptional surface area, tunable pore size and huge CO2 capture efficiency to facilitate a novel multicomponent cyclization by introducing CO2 into extremely reactive organic skeletons. In the presence of a catalytic Cu/CuxOy NP-loaded COF, several 2-bromo-3-alkylacrylic acids combined with several amine derivatives and CO2 (0.1 MPa) are converted to the desired oxazolidinediones in excellent yields (up to 96%) under alkali-free conditions and ambient temperature.

Triazole-based novel bis Schiff base colorimetric and fluorescent turn-on dual chemosensor for Cu2+ and Pb2+: application to living cell imaging and molecular logic gates.

A triazole-based novel bis Schiff base colorimetric and fluorescent chemosensor (L) has been designed, synthesized and characterized by elemental analysis, 1H-NMR, ESI-MS, FTIR spectra and DFT studies. The receptor L showed selective and sensitive colorimetric sensing ability for Cu2+ and Pb2+ ions by changing color from colorless to yellow and light yellow respectively in CH3OH-tris-buffer (1 : 1, v/v). However, it displayed strong fluorescence enhancement upon the addition of both Cu2+ and Pb2+ ions, attributed to the blocking of PET. The fluorometric detection limits for Cu2+ and Pb2+ were found to be 12 × 10-7 M and 9 × 10-7 M and the colorimetric detection limits were 3.7 × 10-6 M and 1.2 × 10-6 M respectively; which are far below the permissible concentration in drinking water determined by WHO. Moreover, it was found that chemosensor L worked as a reversible fluorescence probe towards Cu2+ and Pb2+ ions by the accumulation of S2- and EDTA respectively. Based on the physicochemical and analytical methods like ESI-mass spectrometry, Job plot, FT-IR, 1H-NMR spectra and DFT studies the detection mechanism may be explained as metal coordination, photoinduced electron transfer (PET) as well as an internal charge transfer (ICT) process. The sensor could work in a pH span of 4.0-12.0. The chemosensor L shows its application potential in the detection of Cu2+ and Pb2+ in real samples, living cells and building of molecular logic gate.

A dipodal molecular probe for naked eye detection of trivalent cations (Al3+, Fe3+and Cr3+) in aqueous medium and its applications in real sample analysis and molecular logic gates.

A simple and low cost multifunctional colorimetric receptor L has been designed, synthesized and characterized by 1H-NMR, IR spectroscopy, ESI-MS spectrometry and elemental analysis. The chemosensor L can selectively detect three biologically and environmentally important trivalent metal ions (Al3+, Fe3+and Cr3+) both visually and spectrophotometrically in CH3CN-H2O (1 : 1, v/v) solution in the presence of other biologically relevant metal ions. The Job's plot analyses indicate the 2 : 2 binding stereochemistry for Al3+, Fe3+ and Cr3+ ions with L, which was further confirmed by 1H-NMR and ESI-MS studies. The binding constant values were found to be 2.9 × 104 M-1 for Al3+, 1.079 × 105 M-1 for Fe3+ and 1.366 × 105 M-1 for Cr3+ respectively. The detections limits of the sensor for Al3+ (2.8 × 10-7 M), Fe3+ (1.9 × 10-7 M) and Cr3+ (2.5 × 10-7 M) are far below than the limit set by the World Health Organization (WHO) for drinking water. Moreover, colorimetric test kits for rapid detection of Al3+, Fe3+, and Cr3+ could be successively applied for all practical purposes, indicating its potential use in environmental samples. It has also been used in building molecular logic gates.

Solvent-dependent fluorescent-colorimetric probe for dual monitoring of Al(3+) and Cu(2+) in aqueous solution: an application to bio-imaging.

A novel, quinoline-based smart probe L has been designed for the detection of Al(3+) and Cu(2+) at physiological range. The unprecedented solvent-dependent sensitivities of the probe L for simultaneous detection of Al(3+) and Cu(2+) ions with high selectivity and sensitivity have been observed for the first time. It displays quick responses through visible colorimetric as well as fluorogenic changes towards both Al(3+) and Cu(2+), as delineated by absorption and fluorescence titrations. The sensitivity of the fluorescence-based assay (12.6 nM) for Al(3+) and (18.4 nM) for Cu(2+) is far below the limit recommended in the World Health Organization (WHO) guidelines for drinking water. From (1)H NMR data, the Job plot and the ESI-MS spectrum, 1 : 2 stoichiometric complexations between L and both metals have been established. The geometry and spectral property of L and its metal complexes have been well rationalized by DFT calculations. This probe L has been tested as being highly suitable for mapping Al(3+) and Cu(2+) in human breast cancer cells, MCF7, thus providing a wonderful candidate for tracking Al(3+) and Cu(2+) in biological organisms and processes. The proposed chemosensor L has also been successfully applied for analysis of real samples.

A reversible fluorescent-colorimetric imino-pyridyl bis-Schiff base sensor for expeditious detection of Al(3+) and HSO3(-) in aqueous media.

A reversible fluorescent-colorimetric imino-pyridyl bis-Schiff base receptor (N(1)E,N(4)E)-N(1),N(4)-bis(pyridine-4-ylmethylene)benzene-1,4-diamine for the detection of both Al(3+) and HSO3(-) in aqueous medium has been developed. Receptor exhibits an excellent selective fluorescent-colorimetric response toward Al(3+). The sensitivity of the fluorescent based assay (0.903 µM) for Al(3+) is far below the limit recommended in the World Health Organization (WHO) guidelines for drinking water (7.41 µM). From (1)H NMR data, the Job plot and the ESI-MS spectrum, 1 : 2 stoichiometric complexation between and Al(3+) has been established. Receptor shows remarkable detection ability in a wide pH range of 4-11 and was successfully utilised in the determination of Al(3+) in aqueous solution of bovine serum albumin protein, and of HSO3(-) in real food samples. Moreover, shows a highly selective colorimetric response to HSO3(-) by changing its colour from yellow to colorless immediately without any interference from other anions.