Solvent dependent competition between fluorescence resonance energy transfer and through bond energy transfer in rhodamine appended hexaphenylbenzene derivatives for sensing of Hg2+ ions

Hexaphenylbenzene (HPB) derivatives 5 and 7 having rhodamine B moieties have been designed and synthesized, and have been shown to display solvent dependent. Fluorescence resonance energy transfer (FRET) and through bond energy transfer (TBET) in the presence of Hg2+ ions among the various cations (Cu2+, Pb2+, Zn2+, Ni2+, Cd2+, Ag+, Ba2+, Mg2+, K+, Na+, and Li+) have been tested. Derivative 5 displays quite high through bond energy transfer efficiency in the presence of Hg2+ ions in methanol whereas derivative 7 exhibits better FRET efficiency in the presence of Hg2+ ions in THF and CH3CN than derivative 5.