Naphthyridine derived colorimetric and fluorescent turn off sensors for Ni2+ in aqueous media

Abstract

Highly selective and sensitive 2,7-naphthyridine based colorimetric and fluorescence “Turn Off” chemosensors (L1-L4) for detection of Ni2+ in aqueous media are reported. The receptors (L1-L4) showed a distinct color change from yellow to red by addition of Ni2+ with spectral changes in bands at 535–550 nm. The changes are reversible and pH independent. The detection limits for Ni2+ by (L1-L4) are in the range of 0.2–0.5 µM by UV–Visible data and 0.040–0.47 µM by fluorescence data, which is lower than the permissible value of Ni2+ (1.2 µM) in drinking water defined by EPA. The binding stoichiometries of L1-L4 for Ni2+ were found to be 2:1 through Job’s plot and ESI–MS analysis. Moreover the receptors can be used to quantify Ni2+ in real water samples. Formation of test strips by the dip-stick method increases the practical applicability of the Ni2+ test for “in-the-field” measurements. DFT calculations and AIM analyses supported the experimentally determined 2:1 stoichiometries of complexation. TD-DFT calculations were performed which showed slightly decreased FMO energy gaps due to ligand–metal charge transfer (LMCT).

Organically tuned white-light emission from two zero-dimensional Cd-based hybrids

“…Hence, photoluminescence performances of OIMHMs can be easily tailored by tuned supramolecular assembly modes. 54 Fluorescent and phosphorescent materials have received great attention due to their application in biological imaging, 55,56 optical anti-counterfeiting, 57,58 sensors, 59,60 LED 40,61,62 and so on. The emitted white light resulting from RTP exhibits higher performance than that resulting from the fluorescent counterparts.…”

Non-linear optical properties of 2,7-naphthyridine derivatives for optical switching applications: a DFT study

“…DMSO solvent is used in the study of UV-visible absorption spectra due to the fact that DMSO solvent is the most used solvent in the experimental study of UVvisible absorption spectra of 2,7-naphthyridine derivatives. 72,73 In the UV-vis analysis, one of the conditions for selecting a solvent is that the absorption of solvent should be low or even zero and DMSO is a most suitable solvent to fit this criterion. Solvent effects were also included in the calculations of nonlinear optical parameters using three polar solvents DMSO, methanol and ethanol and two non-polar solvents chloroform and heptane.…”

“…N9 has the highest peak absorption wavelength 72 Other 2,7-naphthyridine derivatives have experimental UV-visible spectral bands in the range 261-450 nm which is increased to 535-550 nm after nickel addition. 73 The designed compounds N1-N10 have maximum absorption wavelength in the range 352-502 nm and the compounds N6, N7, N10 and N9 show absorption peaks at 360.14 nm, 383.14 nm, 440.63 nm and 502.80 nm respectively (see Table 1).…”

Fluorescent and chromogenic organic probes to detect group 10 metal ions: design strategies and sensing applications

“…Ashraf et al (in 2021) designed 130 probes 20a–20d based on 2,7-naphthyridine moiety to detect Ni( ii ) in aqueous medium (Fig. 14).…”