A Catalogue of Orthogonal Complementary Ligand Pairings for Palladium(II) Complexes

Abstract

Molecular recognition is a form of information transfer, seen in the base pairing in DNA which is derived from the identity (acceptor or donor) and number of hydrogen bond sites within each base. Here we report bis‐ligand palladium(II) complexes that exhibit similar complementarity. Pd(II) has square planar four‐coordinate geometry, giving control over ligand orientation and denticity. Pairings were developed using ligand denticity (3 : 1 or 2 : 2), and hydrogen bond capability (AA:DD or AD:DA) or lack thereof. Five pairings were investigated, with two sets of four being found fully orthogonal. The two 3 : 1 pairings exhibited limited ligand exchange. The extent of this exchange varied dependant on solvent from 2 : 1 (desired to undesired) to 6 : 1. A reliable and varied set of ligand pairs have therefore been developed for bis‐ligand coordination sphere engineering in pursuit of sorting for complex molecular architectures and molecular‐level information storage and transfer events.

Stoichiometric Control of Guest Recognition of Self‐Assembled Palladium(II)‐Based Supramolecular Architectures

“…The host displayed the same connectivity as observed in the prior structure, and G 9MA was within range of the planar panel for aromatic π‐π interactions (e. g. from the centroid of the central ring and the Pd(II) ion, 3.389 Å). This 1 : 1 arrangement in the solid state, with hosts with two faces capable of binding two guests, has been observed by us in the past, and is a result of the arrangement giving alternating electron rich‐electron poor pairings [24b,25c] …”

Directing metallo-supramolecular assembly through complementarity

“…6). 72 In our study, five different complexes 73 (both hetero- and homoleptic) were examined which differed in their denticity (3 : 1 and 2 : 2) and in their hydrogen bonding capabilities ( AA : DD or DA : AD ). ortho to coordinating nitrogen atoms in the ligands are either acidic aromatic C–H protons (donors) or N2 triazole nitrogen atoms (acceptors), and these pairs of ligands were designed to be complementary to one another.…”

“…6 A family of five mononuclear Pd 2+ complexes that differ in their denticity (3 : 1 or 2 : 2) or hydrogen bonding capability (AA : DD or AD : DA). 72 Two sets of four complexes exhibited complete orthogonality, represented by blue or red connections. Colours: carbon grey, nitrogen light blue, palladium dark blue.…”