Assignment of Stereochemistry of Facially Protected Bis-porphyrins by Use of a “Molecular Ruler”

Abstract

The power of supramolecular chemistry to solve problems in structural chemistry where conventional techniques such as NMR, UV, and IR spectroscopy failed is demonstrated in the differentiation of the syn‐ and anti‐bis(capped porphyrin) isomers (obtained after condensation of a capped porphyrin monomer) by simple UV/Vis binding studies using bidentate ligands that act as “molecular rulers” (see picture).

Oxygen Activation Chemistry of Pacman and Hangman Porphyrin Architectures Based on Xanthene and Dibenzofuran Spacers

“…To this end, host-guest chemistry of the DPD platform was developed by using stable adducts that were amenable to structural and spectroscopic scrutiny. Sanders' approach (22)(23)(24)(25)(26)(98)(99)(100)(101)(102)(103)(104)(105)(106)(107)(108)(109) of using multifunctional zinc(II) porphyrin hosts with neutral nitrogen donors to form Lewis acid-base inclusion complexes provided an attractive starting point for this strategy. For our purposes, pyrimidine-based guests were selected for investigation.…”

Syn–anti conformational switching: Synthesis and X-ray structures of tweezer and anti form in a zinc porphyrin dimer induced by axial ligands

“…A supramolecular tweezer arising from the insertion of a guest molecule between two binding sites of a molecular host that leads to a fascinating spatial architecture resembles a pincer holding an object. Although bis-porphyrin derivatives are well suited to serve as host compounds for the tweezers [18,19,[24][25][26][27][28][29][30], only a few complexes have been structurally characterized so far [18,19,27].…”

Synthesis and First Studies of the Host–Guest and Substrate Recognition Properties of a Porphyrin‐Tethered Calix[6]arene Ditopic Ligand

“…A solution to overcoming this issue involves the introduction of rigid elements into the ligand such as unsaturated linear or cyclic fragments 32a,34. Alternatively, one can precisely adjust the distance between the two metal sites involved in the coordination to the size of the spacer that separates the two coordinating sites of the ditopic ligand 35. The complexes designed according to this strategy are sometimes referred to as “molecular rulers”, the entropic cost being counterbalanced by the perfect size fit between the ligand and distant metal sites.…”