Chiral and Extended π‐Conjugated Bis(2‐pyridyl)phospholes as Assembling N,P,N Pincers for Coordination‐Driven Synthesis of Supramolecular [2,2]Paracyclophane Analogues

Abstract

Chiral, π-conjugated 3,4-butano-1-phenyl-2,5-bis(2-pyridyl)phosphole derivatives 1a(2,2') and 1a(3) with chiral trans-1,2-diol moieties and fused pinene derivatives, respectively, were prepared from the corresponding chiral diynes by using the Fagan-Nugent method. Their UV/Vis absorption and chiroptical properties (optical rotation and circular dichroism) were studied. Their behavior as N,P,N chelates towards coordination of Cu(I) and formation of chiral supramolecular assemblies with π-conjugated ditopic dicyano ligands was investigated. Chiral C(2)-symmetric rectangles that are [2,2]paracyclophane analogues were obtained, as demonstrated by X-ray crystallography. During the course of this study, the first stable water-soluble phosphole derivative (1a(2)·2 HCl) was prepared. Furthermore, achiral 3,4-butano-1-phenyl-2,5-bis(aza[4]helicene)phosphole 1a(4) was synthesized and displays extended π conjugation. A supramolecular rectangle was obtained by coordination to Cu(I) and assembly with a dicyano stilbene. This coordination-driven supramolecular assembly contains a total of four aza[4]helicene moieties and displays two types of π-π stacking interactions in the solid state, that is, between two helicene moieties and between one helicene and a bridging dicyano ligand. All the supramolecular arrangements are discussed by comparing them with previous work on the parent 3,4-butano-1-phenyl-2,5-bis(2-pyridyl)phosphole.

Simultaneous End‐On/Side‐On Coordination Modes of a Diphosphorus Tetrahedral Complex Imposed by Pre‐organization of Oligometallic CuI Acceptors

“…[23] The solid-state structure of 6 confirmed that the variation of the steric demand associated with the molecular clip used in these reactions (replacement of one equivalent of 1 in B and the dppm ligand in C, respectively, by 2 in 3) altered the organization of the resulting self-assembled supramolecular rectangles. Nevertheless, with compound 6 it was demonstrated that bimetallic complexes carrying 2 with a type IV coordination mode could be used as configurationally stable molecular clips in a coordinationdriven supramolecular assembling process.…”

Helicene-based transition metal complexes: synthesis, properties and applications

“…Coordination-driven synthesis of supramolecular rectangle 60 using bis-aza4]helicene-phosphole 5980 and helicate 62 from helicand 61 81. …”

Chiroptical Properties of Carbo[6]Helicene Derivatives Bearing Extended π‐Conjugated Cyano Substituents

“…This case study of carbo[6]helicenes bearing extended π‐conjugated cyano substituents nicely illustrates how the electronic and optical properties of a [6]helicene can be molecularly engineered by simply grafting a π‐conjugated arm of different vinyl or ethynyl substituents and of different lengths therefore enabling modification of the chiroptical properties of helicenic systems. In the future, the ability of these phenyl‐ethynyl and/or vinyl substituted carbo[6]helicenes bearing cyano groups to be used as ligands for helicene‐based coordination chemistry will be investigated.…”