| dc.description.abstract | The objective of this dissertation is the steric insulation of diplatinum
polyynediyl complexes through the assembly of [2]rotaxanes, a class of mechanically
interlocked molecules (MIMs). The synthetic approach to these MIMs takes advantage
of the active metal template employing a copper(I) iodide macrocycle complex as the
site of an oxidative homocoupling of two terminal alkynes. Various structural
modifications to the macrocyclic precursors are explored.
Firstly the chemistry of polyynes emphasizing diplatinum polyynediyl complexes
as model compounds for molecular wires is presented. Previous studies have revealed a
need for steric insulation of these unsaturated linkers and earlier attempts in this
direction are introduced. Here, a new approach to the steric insulation employing
rotaxanes will be discussed.
Following, a series of macrocyclic precursors to rotaxanes equipped with a 1,10-
phenanthroline moiety available for coordination with copper(I) iodide are described.
These complexes serve as active templates in the syntheses of rotaxanes. Various α,ω-
bis(bromoalkoxy)aryl precursors are prepared via Williamson ether synthesis. These
dibromides are condensed with 2,9-bis(4-hydroxyphenyl)-1,10-phenanthroline in the
presence of K2CO3 to give the corresponding 31- to 35-membered macrocycles. When
the macrocycles are treated with copper(I) iodide, mononuclear 1:1 complexes form in
which the metal cation chelates to the nitrogen donor atoms of the phenanthroline
moiety. The crystal structures of the synthesized macrocycles and their corresponding
complexes are determined and analyzed in the context of DFT calculations and
rotaxanes that can be formed by treatment of the copper(I) iodide macrocycle complexes
with terminal alkynes (e.g., macrocycle dimensions, void volumes). The copper and iodide atoms significantly protrude from the least squares plane of the phenanthroline
moiety (0.46-0.63 Å and 1.65-2.07 Å).
Lastly, the syntheses of various platinum-capped polyynediyl containing
rotaxanes by the oxidative homocoupling of the monoplatinum polyynyl complexes
trans-(Cv6Fv5)(p-tolv3P)v2Pt(C≡vC)n/2H in the presence of copper(I) iodide adducts of the
1,10-phenanthroline-based macrocycles 2,9-(1,10-phenanthrolinediyl)(p-
Cv6Hv4O(CHv2)v6O)v2(1,3-Cv6Hv4) or 2,9-(1,10-phenanthrolinediyl)(p-Cv6Hv4O(CHv2)v6O)v2(2,7-
naphthdiyl) are described. All of these MIMs feature a Pt(C≡vC)vnPt unit (n = 4, 6, 8) that
is threaded through the macrocycle. Crystal structures of three rotaxanes are determined
and analyzed in detail, particularly in regards to geometric perturbations and the degree
of steric Cvsp chain insulation. The ^1H NMR spectra show a number of noteworthy
shielding effects. UV-visible spectra exhibit negligible electronic interactions between
the Pt(C≡C)vnPt axles and macrocycles, although cyclic voltammetry data suggest rapid
reactions following oxidation. Finally, the findings of this work are summarized and a
perspective on potential future studies in this area is offered. | en |
