Synthesis of novel platinum complex core as a selective Ag⁺ sensor and its H-bonded tetrads self-assembled with triarylamine dendrimers for electron/energy transfers

A novel platinum complex PtC with a tri-armed uracil hydrogen-bonded (H-bonded) unit was synthesized via a modular synthetic approach and characterized by ¹H, ¹³C NMR and MALDI-TOF mass spectroscopies. Two H-bonded tetrads, PtC-(TPAD1)₃ and PtC-(TPAD2)₃, based on a metal core PtC complexed with two generations of triarylamine dendrimers, TPAD1 and TPAD2 (with electron-donating nature), were successfully constructed with improved organic solubility via a classical H-bonded self-assembly approach. Supramolecular H-bonding in solution and solid state was elucidated by ¹H NMR titrations, IR spectral studies and time resolved photoluminescence (TRPL) measurements. The electron/energy transfers, as well as the self-assemblies of supramolecular tetrads, were established by UV-Vis and PL titrations and AFM morphological studies. Furthermore, metal complex core PtC showed selective sensitivity towards Ag⁺ ions through fluorescence turn-off responses without any interference from other common metal ions. The 1:1 binding stoichiometry and complexation mechanism between the probe and Ag⁺ ion was established by ¹H NMR titration. Moreover, PL reversibility of PtC + Ag⁺ could be achieved on addition of PMDTA.