Bulky melamine‐based Zn‐porphyrin tweezer as a CD probe of molecular chirality

Abstract

The transfer of chirality from a guest molecule to an achiral host is the subject of significant interest especially when, upon chiral induction, the chiroptical response of the host/guest complex can effectively report the absolute configuration (AC) of the guest. For more than a decade, dimeric metalloporphyrin hosts (tweezers) have been successfully applied as chirality probes for determination of the AC for a wide variety of chiral synthetic compounds and natural products. The objective of this study is to investigate the utility of a new class of melamine-bridged Zn-porphyrin tweezers as sensitive AC reporters. A combined approach based on an experimental CD analysis and a theoretical prediction of the prevailing interporphyrin helicity demonstrates that these tweezers display favorable properties for chiral recognition. Herein, we discuss the application of the melamine-bridged tweezer to the chiral recognition of a diverse set of chiral guests, such as 1,2-diamines, α-amino-esters and amides, secondary alcohols, and 1,2-amino-alcohols. The bulky periphery and the presence of a rigid porphyrin linkage lead, in some cases, to a more enhanced CD sensitivity than that reported earlier with other tweezers.

Porphyrin tweezer receptors: Binding studies, conformational properties and applications

“…More recently, the melamine-based Zn(II)-porphyrin tweezer receptor T10 introduced above and other derivates with different meso-substituents were used as probes of molecular chirality in CD studies [57]. The complexation properties of a series of Zn(II)-bisporphyrins containing the melamine spacer with a pool of chiral ditopic amine guests were investigated.…”

Chiroptical Sensing: A Conceptual Introduction

“…If spectral predictions are not optimal and verifying level of theory do not improve the level of correlation, one may choose to resort to explicit solvent to account for specific solute-solvent and solute-solute (dimer, trimer) interactions. For examples of such a procedure, we refer the interested reader to the literature [65][66][67][68][69].…”

“…This material shows high sensitivity to limonene [97]. In solution, achiral diporphyrins have also been used extensively for chiroptical detection of a large diversity of synthetic chiral compounds and natural chiral products [35,65]. Similarly, ß-cyclodextrin has a well-defined hydrophobic inner cavity and a hydrophilic shell, and it is an appropriate host for forming supramolecular structures.…”

Chiroptical Sensing

“…[82] In solution, achiral diporphyrins have also been extensively used for the chiroptical detection of a large diversity of chiral synthetic compounds and natural products. [24,49] Similarly, β-cyclodextrin is an ideal host for forming supramolecular structure due to its well-defined hydrophobic inner cavity and hydrophillic shell. β-cyclodextrin has the ability to selectively combine miscellaneous inorganic, organic and biomoleculrs into its cavities to the formation of the host-guest inclusion complex.…”