An organometallic ruthenium nanocluster with conjugated aromatic ligand skeleton for explosive sensing
2019; Springer Science+Business Media; Volume: 131; Issue: 2 Linguagem: Inglês
10.1007/s12039-018-1589-y
ISSN0974-3626
AutoresPranav Dave, Bhavesh Agrawal, Jaydev Thakarda, Sagar Bhowmik, Prasenjit Maity,
Tópico(s)Molecular Sensors and Ion Detection
Resumo9-Ethynylphenanthrene (EPT) bound to highly monodispersed Ruthenium (Ru) nanocluster (Ru:EPT) with mean diameter of $$1.5\pm 0.2\,\hbox {nm}$$ and mol wt. of $${\sim }$$ 8600 Da was synthesized via a facile and high yield biphasic ligand exchange protocol using similar sized ethylene glycol (EG)-stabilized Ru clusters (Ru:EG) as precursor. The synthesized organometallic nanocluster was meticulously analyzed to understand its size distribution, oxidation state, crystallinity, optical and luminescence behavior and metal–ligand interfacial structure. Contrary to the extensive quenching of ligand emission by metalcore as usually observed, the ruthenium core here acts as a conductor, which conjugates surface ligands with strong emission property courtesy to an unusual vinylidene-binding motif. Thus, the synthesized nanocluster shows good luminescence property ( $$\upphi = \,{\sim }\, 7\%$$ ) originated from the ligand skeleton and the spherical metal core restricts lateral overlap of phenanthrene moiety to cause any excimer emission. This nanocluster showed high sensitivity for solution phase detection of nitroaromatic explosives through luminescence quenching method ( $$\hbox {K}_{\mathrm{SV}}$$ up to $$4.98 \times 10^{4}\,\hbox {M}^{-1})$$ and mimic the mechanism like conjugated organic polymer. We propose that dynamic $$\uppi -\uppi $$ interaction between Ru bound phenanthrene moiety and nitroaromatic compounds followed by photoinduced electron transfer (PET), as well as Förster Resonance Energy Transfer (FRET), are the possible mechanisms behind this luminescence quenching. SYNOPSIS An organometallic ruthenium nanocluster with $$\sim 8.6 \hbox { kDa mol. wt. }$$ was synthesized, where aromatic phenanthrene ligands were inter-molecularly conjugated through Ru core. The Ru nanocluster showed excellent sensing performance for detection of nitroaromatic explosive molecules through luminescence quenching strategy.
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