Metal Complexes of Cinchonine as Chiral Building Blocks: A Strategy for the Construction of Nanotubular Architectures and Helical Coordination Polymers

Abstract

The first chiral bipyridyl-type metalloligands based on aluminum derivatives of cinchonine (CN-H) were synthesized and characterized by single-crystal X-ray diffraction studies. These bischelate complexes, (CN)(2)AlX [X = Cl (1a), Me (1b)] were found to be effective building blocks for the preparation of novel helical nanotubular architectures as well as chiral bimetallic coordination polymers, as demonstrated by the rational synthesis of a helical structure formed by 1a and ZnCl(2). The applied methodology stands as an exemplary strategy for the rational synthesis of chiral metal-organic frameworks through self-organization driven by nonbonding interactions or coordination, which could potentially find applications in enantioselective separations and catalysis.

Engineering Homochiral Metal‐Organic Frameworks for Heterogeneous Asymmetric Catalysis and Enantioselective Separation

“…[ 105 ] Treatment of aluminum complexes (AlMe 2 Cl or AlMe 3 ) with 2 equiv of cinchonine ( L 17 Figure 25 ). [ 100 ] The 33 cm high chiral column was prepared by loading a glass tube (8 mm inner diameter) with a suspension of 56 in 10% solution of DMF in CH 2 Cl 2 , and a mixture of the sulfi de (PhSMe) and H 2 O 2 was charged directly onto the top of the column.. Each probe contained ca.…”

Effect of Microwave Irradiation on the Catalytic Activity of Palladium Supported Catalysts in the One-Step Isomerisation of Cinchona Alkaloids to Δ3,10-Isobases

“…All the four natural compounds, their derivatives and metal complexes have become more and more interesting catalysts for asymmetric syntheses [6]. Recently they play an important role in the preparation of new chiral nanomaterials [7,8].…”

“…This paper described our work on influence of controlled microwave heating on activity of palladium solid supported (Pd/SS) catalysts in the heterogeneous isomerisation of four natural Cinchona alkaloids. We studied also possibility of analysis and isolation of the geometric isomers Z and E in Δ 3,10 -isomers, as they will be used as chiral ligands [7,8], catalysts and modifiers in asymmetric syntheses [9][10][11][12].…”

Cinchona Alkaloid–Metal Complexes: Noncovalent Porous Materials with Unique Gas Separation Properties

“…Initially we synthesized bischelate aluminum complexes, XAl(CN) 2 (where CN = deprotonated cinchonine), as novel chiral N,N-metalloligands I (Scheme 1), and demonstrated their excellent capability as metallotectons for noncovalent-interaction-driven selfassembly into novel microporous chiral architectures prone to enantioselective sorption, as well as their coordinationdriven self-organization for constructing coordination polymers of helical topology. [11] Herein, we extend this strategy to dinuclear aluminum-cinchone complexes as novel molecular building blocks II to produce flexible homochiral NPMs. We show that the resulting NPMs can compete with classical MOFs as highly selective adsorbents exhibiting unique properties, such as temperature-triggered adsorption as well as very high affinities for H 2 , CO 2 , and CH 4 .…”

“…We note that the synthesis and spectroscopic characterization of 1 was reported previously and the variable-temperature 1 H NMR studies revealed that it exists in solution as a dimeric five-coordinate adduct of formula [Me 2 Al(m-CN)] 2 with a relatively high activation energy (80.8 kJmol À1 K À1 ) for the dissociation of the AlÀN dative bond. [12] As structural details for [R 2 Al(m-CN)] 2 complexes were still lacking, [13] as well as being encouraged by the above-mentioned results for the monomeric XAl(CN) 2 -type complexes, [11] we put a lot of effort into obtaining single crystals of the title compounds suitable for X-ray diffraction studies. We succeeded when THF was used as the crystallization solvent.…”