Self-Assembly of Ring-in-Ring Metallamacrocycle with Alkynylplatinum(II) Bzimpy and Study of Its Aggregation Behaviors

Yiming Li¹, Guifei Huo², Xiaomin Qian¹ and Xiaopeng Li¹*

1 Department of Chemistry, University of South Florida, Tampa FL 33620, USA
2 Shanghai Key Laboratory of Green Chemistry and Chemical Processes, Department of Chemistry,
East China Normal University, Shanghai 200062, China

A new discrete supramolecular ring-in-ring metallamacrocycle functionalized with alkynylplatinum(II) bzimpy moiety was successfully prepared via coordination-driven self-assembly, and the self-assembly properties were investigated by UV−vis absorption, fluorescence emission, ¹H NMR and electrospray ionization mass spectrometry(ESI-MS). To investigate the aggregation behaviors of the ligand and supramolecular complex in solution, hydrophobic alkyl chains were installed inside the metallamacrocycle, six alkynylplatinum(II) bzimpy attached with four hydrophilic polyethylene glycol ether chains were installed outside the metallamacrocycle through alkynylplatinum(II) bond. Strong overlapping signal in NMR spectrum indicated the Pt-Pt and π-π interaction between ligands. With further coordination of terpyridine with metal ions, the distance between Pt-Pt was stretched, and the supramolecule was more likely to assemble into micelle structure based on the transmission electron microscopy(TEM) and scan electron microscopy(SEM) imaging. The supramolecular ring-in-ring macrocycle was fully characterized with 2D NMR spectroscopy (COSY, DOSY and NOESY) and ion-mobility mass spectrometry (IM-MS).