Related Experiment Video
Updated: Jun 8, 2026

Fluorescence Anisotropy as a Tool to Study Protein-protein Interactions
Published on: October 21, 2016
Fluorescence spectroscopic evidence for hydrogen bonding and deprotonation equilibrium between fluoride and a
Pichandi Ashokkumar1, Vayalakkavoor T Ramakrishnan, Perumal Ramamurthy
1National Centre for Ultrafast Processes, University of Madras, Taramani Campus, Chennai 600 113, India.
Abstract:
Interaction of anions with thiourea-linked acridinedione fluorophore was studied by absorption, (1)H NMR, steady-state and time-resolved fluorescence techniques. Addition of AcO(-) and H(2)PO(4)(-) shows a genuine H-bonded complex with thiourea receptor; whereas, F(-) shows stepwise H-bonding and deprotonation of thiourea NH as confirmed by (1)H NMR titration. Free receptor 1 shows emission maximum at 418 nm; whereas, H-bonded complex of 1·F(-) shows a new redshifted emission maximum at 473 nm and the deprotonated 1 exhibits an emission peak at 502 nm. Presence of these three different emitting species was probed by 3D emission spectroscopic studies. Equilibrium between the free receptor 1, 1·F(-) H-bonded complex and deprotonated 1 was confirmed by time-resolved fluorescence studies. Time-resolved area normalised emission spectra (TRANES) of 1 in the presence of F(-) shows two isoemissive points at 456 and 479 nm between time delays of 0-0.5 ns and 1-20 ns, respectively, due to the existence of three emitting species in equilibrium. Observation of such an equilibrium based on fluorescence spectroscopic studies further proves the earlier reported absorption and (1)H NMR spectroscopic studies of H-bonding and deprotonation processes and also illustrates the dynamics of anion-receptor interactions.
More Related Videos
Related Concept Videos
Hydrogen Bonds
Hydrogen Bonds
Valence Bond Theory
Electrophilic Aromatic Substitution: Fluorination and Iodination of Benzene
Molecular Shape and Polarity
Variables Affecting Phosphorescence and Fluorescence

