A Phosphorescent Platinum(II) Bipyridyl Supramolecular Polymer Based on Quadruple Hydrogen Bonds

• Published in: Chemistry : a European journal 2016-12, Vol.22 (50), p.18132-18139
• Main Authors: Liu, Fang-Wei, Niu, Li-Ya, Chen, Yong, Ramamurthy, Vaidhyanathan, Wu, Li-Zhu, Tung, Chen-Ho, Chen, Yu-Zhe, Yang, Qing-Zheng
• Format: Article
• Language: English
• Subjects: Chemistry; Hydrogen bonding; In vitro testing; Medical imaging; Nanoparticles; Phosphorescence; Platinum; Polymerization; quadruple hydrogen bonding; ring-chain polymerization; Supramolecular polymers
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201603467

A platinum(II) bipyridyl complex bearing bis‐ureidopyrimidinone (Pt‐bisUPy) has been designed and its self‐assembling behavior has been thoroughly investigated by 1H NMR, DOSY NMR, Ubbelohde viscometry analysis, UV/Vis, and emission spectroscopies. Pt‐bisUPy underwent concentration‐dependent ring‐chain polymerization in apolar solvents. Hydrogen‐bonding interactions play an important role during the formation of the supramolecular polymers. Hydrogen‐bonded supramolecular polymers were transformed to nanoparticles in water through the miniemulsion method. These nanoparticles showed strong π–π excimeric emission. Metal‐metal‐to‐ligand charge transfer (MMLCT) from Pt–Pt interactions was not significant in the emission spectrum. The phosphorescence of the nanoparticle persisted even under aerobic conditions. The triplet state of these phosphorescent nanomaterials were long‐lived and possessed moderate emission quantum yields. Furthermore, the low toxicity of these materials promises a place for them in in vitro and in vivo bioimaging. Hydrogen bonding in supramolecular polymers: A newly synthesized platinum(II) bipyridyl complex with bis‐ureidopyrimidinone undergoes concentration‐dependent ring‐chain supramolecular polymerization in dichloromethane. Orthogonal hydrogen‐bonding, Pt–Pt, and π–π interactions are shown to establish a delicate balance in the formation of the supramolecular polymer as well as its corresponding nanoparticles. The oxygen‐insensitive phosphorescent nanoparticles show great potential in in vitro and in vivo bioimaging (see figure).