Zirconium, a medically important transition metal, found extensive application and was found to be relatively safe, however, continuous exposure will lead to adverse effects. Though zirconium is considered as a safe metal in biomaterials, no reliable sensing methodologies have been developed. In the present report, for the detection of medically influential zirconium(IV) ions, a graphene-based carbonaceous material has been developed. Covalent modification of graphene oxide (GO) with 2-bis(pyridine-2-ylmethyl)amino)ethan-1-ol (PAE) provides a new material GOP which is characterized using various analytical techniques such as elemental analysis, energy dispersive spectroscopy (EDS), FTIR, PXRD, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and microscopic techniques SEM and HRTEM. All the analytical characterization techniques strongly supported the formation of covalently 2-bis(pyridine-2-ylmethyl)amino)ethan-1-ol tethered GO through an ester bond. Upon testing with a series of metal cations, intriguingly, an excellent photoluminescence response has been selectively originated from GOP with Zr(IV) in aqueous medium and it is utilized for the detection of Zr(IV). High selectivity toward Zr(IV) over the presence of other common coexisting metal ions was also demonstrated. Specific "turn-on" fluorescence response of GOP in the presence of Zr(IV) ion is rationalized via Fluorescence Resonance Energy Transfer (FRET) mechanism owing to the presence of ester bond as a spacer which brings PAE and GO closer. Further, the GOP is highly stable and sustainable, could recover and reuse for further sensor studies. The newly developed carbonaceous GOP material offers a new methodology for the detection of Zr(IV) in an aqueous medium with LOD of 27 ng/mL.

Ruthenium, a vital transition metal wildly employed in diverse applications from medicinal to material applications. Though ruthenium has positioned as safe and relatively less toxic than other metals, continuous exposure...

<div>Since the development of supramolecular chemistry, synthetic macrocycles</div><div>have also played an inevitable role in constructing the host-guest system. Among</div><div>pillar[n]arenes, in short pillarenes, a decade-old younger member in the supramolecular</div><div>family, after reported by Ogoshi et al. in 2008, has gained considerable attention. Due</div><div>to the straightforward preparation methods, tunable cavity size, and symmetrical</div><div>architecture makes it an ideal candidate in the supramolecular family. With this</div><div>perspective, this chapter discusses a brief introduction to the synthesis,</div><div>characterization, and structural features of different sizes of pillarenes. The presence of</div><div>a confined hydrophobic and π-electron-rich cavity provided by a paraxyl ether or</div><div>hydroquinone units offers a unique host-guest recognition capability towards positively</div><div>charged and neutral molecules. Notably, the presence of a cavity with an aromatic wall</div><div>provides a broad luminescent platform for various photophysical studies. This chapter</div><div>elaborates on the contribution of pillarenes in tuning the photophysical properties of the</div><div>small guest molecules and the formation of luminescent supramolecular materials.</div><div>Further, the functionalization on the outer of the pillarenes has influenced the</div><div>photophysical responses such as absorption and fluorescence, which paved a pathway</div><div>for the development of supramolecular organic light-emitting functional material and</div><div>novel sensor materials also discussed in this chapter. Finally, this chapter discusses all</div><div>the progress and applications of luminescence pillarenes and their derivatives.</div>