Size and Geometry Impact the Chiroptical Properties of Double Nanohoops

High Resolution Image Download MS PowerPoint Slide Conjugated nanohoops have attracted much attention in recent years due to their unique optoelectronic properties. A more complex geometry, in which two nanohoops are covalently linked to form a so-called double nanohoop, can have a significant influence on the morphology, (chir)optical properties and supramolecular interactions compared to a single nanohoop. Herein, we present the systematic design, synthesis, structural and chiroptical analysis of a novel series of three chiral double nanohoops together with their single hoop reference compounds. They each incorporate a tetrahydroindeno[2,1- a ]indene-5,10-diol unit as an asymmetric bridge with central chirality. Notably, they display high photoluminescence quantum yields of 79–95%, along with distinct trends in absorption, emission, and energy transfer dynamics. Enantiomers of the double and reference single nanohoops were successfully separated by HPLC using a chiral stationary phase, and their chiroptical properties were investigated through electronic circular dichroism (ECD) and circularly polarized luminescence (CPL) spectroscopy revealing increased asymmetry factors ( g abs ) compared to their reference compounds. Our study provides a systematic exploration of how size, geometry, and asymmetry impact the optoelectronic behavior of chiral double nanohoops and offers valuable insight for the development of high-performance chiroptical materials.