Chiral molecular polygons based on the Pt-alkynyl linkage: Self-assembly, characterization, and functionalization

Treatment of 2,2'-diacetoxy- 1, 1'-binaphthyl-6,6'-bis(ethyne), L-H-2 with one equiv of trans-Pt(PEt3)(2)Cl-2 led to a mixture of different sizes of chiral metallocycles [trans-(PEt3)(2)Pt(L)](n) (n = 3-8, 1-6). Each of the chiral molecular polygons 1-6 was purified by silica-gel column chromatography and characterized by H-1, C-13{H-1}, and P-31{H-1} NMR spectroscopy, MS, IR, UV-Vis, and circular dichroism (CD) spectroscopies, size exclusion chromatography, and microanalysis. Chiral molecular square 2 was also characterized by single-crystal X-ray diffraction. The acetyl groups of 2 were readily deprotected under mild conditions to generate 2a which possesses exposed chiral dihydroxy functional groups. The dihydroxy groups were functionalized with n-octadecyl chains or Frechet-type dendrons to generate dendritic molecules built on a chiral molecular square core. This work shows the potential of generating interesting functional supramolecular systems based oil Pt-alkynyl chiral molecular polygons. (c) 2005 Published by Elsevier B.V.