Engineering macrocyclic figure-eight motif

Abstract

The design and synthesis of figure-eight macrocycles are very scarce owing to the intricacies and lack of predictability from first principles. This review emphasizes on discrete macrocyclic systems both synthetic and natural with a defined figure eight knotted topology. In almost all the helical macrocycles, the helical arrangement is held by intramolecular hydrogen bonding or as a backbone requirement, but in all cases, a planar graph can be drawn and so these compounds are trivial from the topological stand point. Nature presents great deal of complexity in terms of structures in macromolecules like DNA and proteins and also displays intriguing topology in simple natural products. Patellamide, tawicyclamides, nosiheptide and thiostrepton are natural products with figure eight topology which shows interesting biological activity. Expanded porphyrins, Cu(II) complexes of thiomacrocycles, cyclic peptides and oligoesters are synthetic macrocycles showing intriguing topology. Analysis of structure and folding behaviour will enable chemists to design molecules with intriguing topology.

Chemistry ofmeso-Aryl-Substituted Expanded Porphyrins: Aromaticity and Molecular Twist

“…Vogel and co-workers shed light on such a possibility in their octaphyrin(2.1.0.1.2.1.0.1) 399 in 1999 (Figure ). , Octaphyrin 399 with a figure-eight structure was successfully separated on a chiral high-performance liquid chromatography (HPLC) column in a preparative scale. The circular dichroism (CD) spectra of the enantiomers of 399 showed mirror-imaged Cotton effects.…”

A Conjugated Figure‐of‐Eight Oligoparaphenylene Nanohoop with Adaptive Cavities Derived from Cyclooctatetrathiophene Core

“…[4] From the perspective of molecular design, fusing two CPPs by different linkers could assemble figure-of-eight bismacrocyclic nanohoops. [5] Novel molecular topologies and properties have been realized from the dual p-conjugated cavities tethered by linkers such as anthracene photodimer, pentiptycene,bicarbazole,spirobifluorene,and twisted arenes (Figure 1b). [6] With well-designed substitutions at appropriate positions,all of the aforementioned linkers install rigidity that helps to reinforce shape-persistencyo ft he strained nanohoops.T ot he best of our knowledge,t he highly strained figure-of-eight nanohoop featuring guest-adaptive flexible shapes remains elusive.…”

Di‐2,7‐pyrenidecaphyrin(1.1.0.0.0.1.1.0.0.0) and Its Bis‐Organopalladium Complexes: Synthesis and Chiroptical Properties

“…Not surprisingly therefore, the preparation of syn-thetic constructs with ostensibly analogous topological chiral features or equivalents in terms of molecular graphs has attracted tremendous interest in recent years. [3] This interest reflects their potential utility in asymmetric catalysis as well as in the preparation of functional materials that exploit the chiroptical properties of chiral macrocyclic chromophores, such as their circular dichroism (CD) and circularly polarized luminescence (CPL) features. [4] Particular emphasis has been placed on the preparation of π-electron-based topologically chiral systems, especially those with highly adoptable figure-of-eight double helicate structures.…”