Synthesis and Photophysical Study of Luminescent Platinum(II) 2,6-Bis(N-dodecylbenzimidazol-2′-yl)pyridine Foldamers and Their Supramolecular Assembly and Metallogel Formation

Abstract

Luminescent dinuclear alkynylplatinum(II) metallofoldamers with an oligomeric m-phenyleneethynylene backbone have been designed with the incorporation of a sterically undemanding and π-conjugated 2,6-bis(Ndodecylbenzimidazol-2′-yl)pyridine pincer ligand. The complex with the optimal chain length has been found to exhibit gelation behavior via stabilization by non-covalent Pt···Pt and π−π stacking interactions in the hierarchical architecture constructed from the single-turn helix. The chain lengths of the complexes have been found to be a critical determinant for their gelation behavior, conformations, and morphologies. Such a gelation process has been found to undergo a cooperative assembly mechanism. Their self-assembly via the Pt···Pt and π−π stacking interactions has been studied by 1H NMR, 2D ROESY NMR, electronic absorption and emission spectroscopy. Density functional theory calculations have provided further insights into the folded state geometry of this class of metallofoldamers.[1] Acknowledgements Financial supports from the URC Strategic Research Theme on New Materials, the University Grants Committee Areas of Excellence (AoE) Scheme (AoE/P-03/08), a General Research Fund (GRF) grant from the Research Grants Council of the Hong Kong Special Administrative Region, People’s Republic of China (HKU 17334216), and the National Basic Research Program of China (973 Program; 2013CB834701) are highly acknowledged. Reference: [1] M. H.-Y. Chan, M. Ng, S. Y.-L. Leung, W. H. Lam, V. W.-W. Yam, J. Am. Chem. Soc., 2017, 139, 8639