From Hetero- to Homochiral Bis(metallahelicene)s Based on a Pt^III−Pt^III Bonded Scaffold: Isomerization, Structure, and Chiroptical Properties

Abstract

Hetero- and homochiral diastereomeric bis(metallahelicene)s have been synthesized. They possess a rare Pt(III)-Pt(III) scaffold bridged by benzoato ligands. It is shown that heterochiral (P,M)-bis(Pt(III)-[6]helicene) can isomerize into the homochiral (P,P)- and (M,M)-bis(Pt(III)-[6]helicene). A theoretical study shows a unique σ-π conjugation between the two π-helices and the σ-Pt(III)-Pt(III) scaffold that impacts the strong chiroptical properties.

One-pot synthesis of anhydrous silver carboxylates from silver(i) fluoride

“…31 Some variations involve the in situ preparation of Ag 2 CO 3 and its reaction with the carboxylic acid, 32 or the addition of freshly prepared Ag 2 O to a basic solution of the carboxylic acid. However, a subsequent paper from Anger et al 35 showed that the oxidation could be carried out equally as well using Ag I and, indeed, early reports of related Pt III dimers had also used silver as an oxidant in the preparation. However, the efficiency decreases significantly when larger organic groups or water-insoluble carboxylic acids are involved.…”

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

“…For compatibility with our previous work on helicene derivatives, Density Functional Theory (DFT) geometry optimizations were initially performed with the Turbomole program version 5.7.1, employing the BP exchange‐correlation functional and a split‐valence basis set with one set of polarization functions for nonhydrogen atoms (SV(P)) . Computations with this functional and basis set combination are referred to as BP in the following.…”

Circular Dichroism Spectroscopy Study of Crystalline‐to‐Amorphous Transformation in Chiral Platinum(II) Complexes

“…[13][14][15][16] Nevertheless, solidstate CD spectroscopy can provide valuable information not only on molecular conformations and configurations, but also on intermolecular interactions in the solid state. 24,25 We first synthesized and characterized two couples of enantiomeric cyclometalated platinum(II) complexes containing chiral terdentate N^C^N ligands: Pt(L 1a )Cl (1a), Pt(L 1b )Cl (1b) and Pt(L 1a )(C C À Ph) (2a), Pt(L 1b )(C C À Ph) (2b) (L 1a = (+)-1,3-di-(2-(4,5-pinene) pyridyl)benzene, L 1b = (À)-1,3-di-(2-(4,5-pinene)pyridyl)benzene) (Scheme 1). For example, Crudden et al observed chirality transmission in the solid state of a periodic mesoporous organosilicate (PMO) material.…”