Directed Assembly of Mesoscopic Metallocycles with Controllable Size, Chirality, and Functionality Based on the Robust Pt−Alkynyl Linkage

This paper describes expeditious stepwise directed assembly of large homochiral metallocycles
with up to 38 6,6‘-bis(alkynyl)-1,1‘-binaphthalene bridging ligands (L) and 38 trans-Pt(PEt3)2 ([Pt]) centers
and with cavities as large as 22 nm in diameter. These unprecedented mesoscopic metallocycles are
synthesized by cyclization of different lengths of oligomeric building blocks, Lm[Pt]m+1Cl2 (m = 1, 2, 3, 5, 7,
11, 19, and 31) and [Pt]nLn+1H2 (n = 1, 2, 3, 4, 5, 6, 10, 18, and 30), and have been characterized by a
variety of techniques, including 1H{31P}, 13C{1H}, and 31P{1H} NMR spectroscopy, MALDI-TOF MS,
elemental analysis, FT-IR, UV−vis, CD, size-exclusion chromatography, and diffusion-ordered NMR
spectroscopy. The present synthetic methodology was also extended to the synthesis of non-homochiral
metallocycles of very different topologies and macrocyclic structures with additional functional groups
precisely placed at different positions. This work provides a general strategy for the construction of
nanoscopic and mesoscopic functional supramolecular architectures of controllable size, chirality, and
functionality that cannot be accessed from the existing synthetic approaches.