Li+-Induced fluorescent metallogel: a case of ESIPT-CHEF and ICT phenomenon
- 10 August 2018
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Physical Chemistry Chemical Physics
- Vol. 20 (36), 23762-23772
- https://doi.org/10.1039/c8cp04579h
Abstract
A fluorescent metallogel (1% w/v) has been synthesized from non-fluorescent ingredients viz. the smallest possible low molecular weight aromatic symmetrical ligand H2SA (1) and LiOH in a chloroform and methanol mixture. The chelation of Li+ is not only responsible for the inhibition of excited state intramolecular proton transfer (ESIPT) or the origin of fluorescence through chelation enhanced fluorescence (CHEF) in 1, but also for aggregation leading to gelation. The metallogel obtained from 1/Li+ reveals a fibrous morphology while 1 with other, bigger size, alkali metal ions like Na+/K+/Cs+ demonstrates the growth of crystals with different shapes. The effect of the size of the alkali metal ion over gel formation is well explored by FTIR, UV-vis, fluorescence, average lifetime measurements, SEM and PXRD. The metallogel shows multi-stimuli responsive behaviour towards thermal and mechanical stress as well as reswelling properties. The regioisomer H2PBA (2) also shows emission upon treatment with LiOH due to the presence of intramolecular charge transfer (ICT), this is well established by various experiments. The mechanism of gel formation is well established by FTIR, 1H NMR, UV-vis, fluorescence, lifetime measurements, SEM and single crystal and powder XRD instrumental techniques. The involvement of various phenomena in gel formation has been further supported by other synthesized model compounds viz. H2MBA (3), PMO (4), H2SEA (5) and H2SPA (6). True gel phase material is proved by detailed rheological experiments.Keywords
Funding Information
- Department of Science and Technology, Ministry of Science and Technology (IFA-14/CH-156)
This publication has 85 references indexed in Scilit:
- Coordination polymer gels with important environmental and biological applicationsChemical Society Reviews, 2012
- A Highly Selective Fluorescent Sensor for Distinguishing Cadmium from Zinc Ions Based on a Quinoline PlatformInorganic Chemistry, 2012
- Zn2+ Binding‐Enabled Excited State Intramolecular Proton Transfer: A Step toward New Near‐Infrared Fluorescent Probes for Imaging ApplicationsAdvanced Healthcare Materials, 2012
- OLEX2: a complete structure solution, refinement and analysis programJournal of Applied Crystallography, 2009
- Supramolecular gelling agents: can they be designed?Chemical Society Reviews, 2008
- Photoinduced Intramolecular Charge Transfer in Push−Pull Polyenes: Effects of Solvation, Electron-Donor Group, and Polyenic Chain LengthThe Journal of Physical Chemistry B, 2007
- Quadrupolar π‐Gels: Sol–Gel Tunable Red–Green–Blue Emission in Donor–Acceptor‐Type Oligo(p‐phenylenevinylene)sAdvanced Materials, 2007
- A Diruthenum(III) Complex Possessing a Diazine and Two Chloride Bridges: Synthesis, Structure, and PropertiesInorganic Chemistry, 2001
- Ultrafast Nonradiative Relaxation Dynamics of EumelaninThe Journal of Physical Chemistry B, 2001
- The dissipation of excitation energy in methoxyflavones by internal conversionJournal of Photochemistry and Photobiology A: Chemistry, 1996