Simple Colorimetric and Fluorescence Chemosensing Probe for Selective Detection of Sn2+ Ions in an Aqueous Solution: Evaluation of the Novel Sensing Mechanism and Its Bioimaging Applications.

An easily accessible colorimetric and fluorescence probe 4-((3-chloro-1,4-dioxo-1,4-dihydronaphthalen-2-yl)amino)benzenesulfonamide (4CBS) was successfully developed for the selective and sensitive detection of Sn2+ in an aqueous solution. The sensing mechanism involves reduction of -C═O into -C-OH groups in 4CBS upon the addition of Sn2+, which initiates the fluorescence turn-on mode. A better linear relationship was achieved between fluorescence intensity and Sn2+ concentration in the range of 0-62.5 µM, with a detection limit (LOD) of 0.115 µM. The binding mechanism of 4CBS for Sn2+ was confirmed by Fourier transform infrared analysis, NMR titrations, and mass (electrospray ionization) spectral analysis. Likewise, the proposed sensing mechanism was supported by quantum chemical calculations. Moreover, bioimaging studies demonstrated that the chemosensing probe 4CBS is an effective fluorescent marker for the detection of Sn2+ in living cells and zebrafish. Significantly, 4CBS was able to discriminate between Sn2+ in human cancer cells and Sn2+ in normal live cells.

Simple Fluorescence Turn-On Chemosensor for Selective Detection of Ba2+ Ion and Its Live Cell Imaging.

A phenoxazine-based fluorescence chemosensor 4PB [(4-(tert-butyl)-N-(4-((4-((5-oxo-5H-benzo[a]phenoxazin-6-yl)amino)phenyl)sulfonyl)phenyl)benzamide)] was designed and synthesized by a simple synthetic methods. The 4PB fluorescence chemosensor selectively detects Ba2+ in the existence of other alkaline metal ions. In addition, 4PB showed high selectivity and sensitivity for Ba2+ detection. The detection limit of 4PB was 0.282 µM and the binding constant was 1.0 × 106 M-1 in CH3CN/H2O (97.5:2.5 v/v, HEPES = 1.25 mM, pH 7.3) medium. This chemosensor functioned through the intramolecular charge transfer (ICT) mechanism, which was further confirmed by DFT studies. Live cell imaging in MCF-7 cells confirmed the cell permeability of 4PB and its capability for specific detection of Ba2+ in living cells.

Synthesis, Characterization and Solvatochromic Studies Using the Solvent Polarity Parameter, ENT on 2-Chloro-3-Ethylamino-1,4-Naphthoquinone.

Quinones are molecules with varied biological activities and electronic properties which are used for important applications [1, 2]. Quinone with a heteroatom substituted, namely 2-chloro-3-ethylamino-1,4-naphthoquinone (N-CAN) was synthesized and characterized by various techniques such as H1-NMR, C13-NMR, Mass spectroscopy and FT-IR spectroscopy. In this study, the solvatochromic effects on the spectral properties of 2-chloro-3-ethylamino-1,4-naphthoquinone have been investigated in different solvents taking into consideration, the solvent parameters like dielectric constant (ε) and refractive index (η) of different solvent polarities. Using Lippert-Mataga, Bakshiev's, Kawski-Chamma-Viallet and Reichardt equations, the ground state (µg) and excited state (µe) dipole moments were calculated. The angle between the excited state and ground state dipole moments were also calculated. Graphical Abstract ᅟ.

Designing benzosiloles for better optoelectronic properties using DFT & TDDFT approaches.

Like siloles, benzosiloles have low lying LUMOs due to σ*-π* conjugation between Si and the butadiene moiety but are more amenable for structural tuning. In total, 27 benzosiloles, 12 of them already synthesized and another 15 newly reported here, have been investigated using DFT and TDDFT calculations with an aim to check their suitability for optoelectronic applications. Our results show that all these molecules have excellent π-conjugation throughout. Frontier molecular orbital analysis gives an estimate of the band gap of these benzosilole derivatives and further reveals that the LUMOs are highly localized on the benzosilole moiety whereas HOMOs are localized on both the benzosilole moiety and the substituents. TDDFT calculations have been performed to understand the absorption properties in gas and solvent phases. PCM calculations show that solvation has a minimum effect on absorption maxima. Among the different functionals, PBE0 was found to perform well compared to other functionals and the computed absorption spectra are in good agreement with experiments. Among the designed candidates, styryl substituted benzosiloles are the most promising, showing higher wavelength of absorption and would make better OLED materials. NBO and AIM analysis provide evidence for complete delocalization in these systems. It is interesting to note that eleven out of the fifteen newly designed candidates have lower band gaps than the best known benzosilole derivatives synthesized so far.