|Name||Mr. Bo Song|
|Organization||University of South Florida|
Direct Self-Assembly & Characterization of 2D and 3D Star-Shaped Metallo-Supramolecules
Bo Song, Zhe Zhang, Dr. Xiaopeng Li
Chemistry Department, University of South Florida
The Star of David, a hexagram or the compound of two equilateral triangles recognized as the symbol of Jewry, has remained as a formidable challenge to synthetic chemists in search of its (supra)molecular expression due to the structural complexity of this geometry. Over the past few decades, several strategies, including stepwise self-assembly as well as template-directed synthesis have been manipulated on the journey toward this fancy structure. We herein designed a direct self-assembly of 2D and 3D Star of David using a tetratopic pyridyl ligand with 180° diplatinum(II) acceptor and naked Pd2+, respectively. 2D Star of David structure was achieved by the self-assembly of tetratopic pyridyl-based ligand with 180° diplatinum(II) acceptor at 1:2 ratio, while the 3D Star of David was achieved by the self-assembly of ligand and Pd2+ in 1:1 ratio. It is noteworthy that alkane chains were introduced into the ligand to improve solubility for the 3D structure. The molecular compositions, shapes and sizes of supramolecular complexes were characterized via multi-nuclear (1H, 13C, 31P) and multi-dimensional (COSY, NOESY, DOSY) NMR techniques, electrospray ionization-mass spectrometry (ESI-MS) as well as ion-mobility mass spectrometry (IM-MS). X-ray crystallographic analysis was also applied to verify the structure. AFM and TEM were employed to directly visualize individual supramolecules. Finally, the stabilities of the 2D and 3D structures were measured and compared using gradient tandem-mass spectrometry (gMS2). The high stability of 3D Star of David was correlated to its high density of coordination sites (DOCS).