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