Heads or Tails? Sandwich-Type Metallo Complexes of Hexakis(2,3-di-O-methyl)-α-cyclodextrin

Abstract

Native and synthetically modified cyclodextrins (CDs) are useful building blocks in construction of large coordination complexes and porous materials with various applications. Sandwich-type complexes (STCs) are one of the important groups in this area. Usually, coordination of secondary hydroxyls or the "head" portal of native CD molecules to a notional multinuclear ring of metal cations leads to formation of head-to-head STCs. Our study introduces a new CD-ligand, hexakis(2,3-di-O-methyl)-α-cyclodextrin, which enables formation of intriguing head-to-head, but also novel tail-to-tail STCs. Homometallic silver-based head-to-head STCs, AgPF6-STC and AgClO4-STC, were obtained by coordination of ligand methoxy groups to six Ag + , while bulky counter-anions are located on the outside but also filling the inner space of infinite linear channels formed. In contrast, unique homometallic tail-to-tail RbF-STC was prepared by complexation of primary hydroxyls, "tails", to twelve Rb + tightly interconnected by twelve Fcreating complex structure with accessible pores for potential gas adsorptions.

Nanotechnology-based approaches for targeting and delivery of drugs via Hexakis (m-PE) macrocycles

“…Therefore, to have a comparison between experimental and theoretical chemical shifts, the obtained results are compared with the experimental data. The experimental chemical shift of protons attached to carbon and nitrogen in the aromatic and amide regions of the hexakis monomer is about 7.9–9.08 ppm, which is reported by Gong et al 12 and similar to our predicted values (Table S5 ). Besides, 1 H NMR calculations are performed on hexakis dimers to understand the dimerization process of (m-PE) macrocycles.…”

“…Among the different ring-shaped macrocycles, those with non-deformable cavities and rigid backbones are of particular interest. Because the stacking of such macrocycles creates structures with strictly defined inner and outer diameters, along with the internal pores 11 , 12 . One kind of these ring-like structures is based on oligo-(phenylene ethynylene) rigid backbones that have also been widely studied 13 .…”

Emerging Trends in Nanotechnology-based Delivery Approaches: Hexakis (m-PE) Macrocycles as a Novel Therapeutics

“…Among the different ring-shaped macrocycles, those with non-deformable cavities and rigid backbones are of particular interest. Because the stacking of such macrocycles creates structures with strictly defined inner and outer diameters, along with the internal pores 10,11 . One kind of these ring-like structures is based on oligo-(phenylene ethynylene) rigid backbones that have also been widely studied 12 .…”