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

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. Chirality, 2011. © 2011 Wiley‐Liss, Inc.