Abstract
A novel nanoprobe was designed and synthesized by functionalizing chitosan-carbon dots (CDs) with a modified bipyridine-based heterocyclic molecule, 4-(pyridine-2-yl)-3H-pyrrolo[2,3-c]quinoline (PPQ), to detect trace amount of water via fluorescence methods. The functionalized CDs (PPQ-CDs) were thoroughly characterized using dynamic light scattering, UV-vis, X-ray diffraction, Fourier transform infrared, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and NMR techniques. The modified fluorescence intensity of PPQ-CDs was found to be an excellent indicator for water in organic solvents. The PPQ-CDs showed very weak fluorescence intensity in organic solvents due to a possible photoinduced electron transfer (PET) process between PPQ pyrrole nitrogen and acceptor groups of CDs. However, sequential addition of trace amount of water led to continuous enhancement in the fluorescence intensity for the PPQ-CD nanocomposites. The mechanism was proposed to follow suppression of the PET process due to the formation of "free-ions" by the proton transfer from the CD carboxyl group to pyrrole nitrogen through water bridging. The limit of water detection was determined to be 0.023% (v/v) in DMSO.
Original language | English |
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Pages (from-to) | 11301-11311 |
Number of pages | 11 |
Journal | ACS Omega |
Volume | 4 |
Issue number | 6 |
DOIs | |
State | Published - 30 Jun 2019 |
Externally published | Yes |
Bibliographical note
Publisher Copyright:© 2019 American Chemical Society.
Funding
S.P. thanks the DST-inspire (IF150605) scheme for providing the senior research fellowship. Authors gratefully acknowledge the support from the Department of Science and Technology, India for the FIST grant SR/FST/CSI-240/2012. Central Analytical Facility of BITS Pilani Hyderabad Campus is gratefully acknowledged for 1 H NMR and TCSPC experiments.
Funders | Funder number |
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DST-INSPIRE | IF150605 |
FIST | SR/FST/CSI-240/2012 |
Department of Science and Technology, Government of Kerala |