Expanding the Chemical Space of Biocompatible Fluorophores: Nanohoops in Cells

Abstract

The design and optimization of fluorescent molecules has driven the ability to interrogate complex biological events in real time. Notably, most advances in bioimaging fluorophores are based on optimization of core structures that have been known for over a century. Recently, new synthetic methods have resulted in an explosion of nonplanar conjugated macrocyclic molecules with unique optical properties yet to be harnessed in a biological context. Herein we report the synthesis of the first aqueous-soluble carbon nanohoop (i.e., a macrocyclic slice of a carbon nanotube prepared via organic synthesis) and demonstrate its bioimaging capabilities in live cells. Moreover, we illustrate that these scaffolds can be easily modified by well-established “click” chemistry to enable targeted live cell imaging. This work establishes the nanohoops as an exciting new class of macrocyclic fluorophores poised for further development as novel bioimaging tools.

[4]Cyclo‐N‐ethyl‐2,7‐carbazole: Synthesis, Structural, Electronic and Charge Transport Properties

“…[3][4][5][6][7] In addition, studies on the influence of the nanoring size and of the building units on the structural, electronic, physical, chiral and encapsulating properties have already shown the diversity of this field. [3][4][5][6][7][8] The growinginterestinnanorings chemistry and physics has led to recent applications such as imaging tools in biology [9] or complexation of single-walledc arbonn anotubes. [10] In 2016, Nuckolls and co-workers have shown the severala dvantages of cyclic oligomers over corresponding linear counterparts in electronics devices.…”

Strain‐Promoted Reactivity of Alkyne‐Containing Cycloparaphenylenes

“…Herein, we merge the concept of alkyne-based strain-promoted reactions with [n]cycloparaphenylenes ([n]CPPs)-inherently warped conjugated macrocycles that have garnered widespread attention because of their relationship to carbon nanotubes and their unique sizedependent properties. [20] To probe this,wedeveloped aconcise and modular synthetic route for aseries of alkyne-containing nanohoops of various sizes 1-3.S tructural analysis based on Figure 1. [20] To probe this,wedeveloped aconcise and modular synthetic route for aseries of alkyne-containing nanohoops of various sizes 1-3.S tructural analysis based on Figure 1.…”

“…[19] We hypothesized that, although the reactivity of bent alkynes has been examined in many contexts,t hese inherently fluorescent macrocycles with radially oriented p-systems could provide unique scaffolds with precisely tunable and perhaps increased reactivity.Moreover, efficient conjugation by click chemistry would afford asimple way to incorporate these fascinating building blocks into functional materials. [20] To probe this,wedeveloped aconcise and modular synthetic route for aseries of alkyne-containing nanohoops of various sizes 1-3.S tructural analysis based on Figure 1. The development of archetypal angle-strained alkynes that have laid the foundationsf or aryne and bioorthogonalchemistry; starting from 1,2-didehydrobenzene [8] and cyclooctyne in the 1950s.…”

Nanohoop Rotaxanes from Active Metal Template Syntheses and Their Potential in Sensing Applications

“…These shape‐persistent macrocycles can be prepared with varying size and atomic composition (Figure b), which has unveiled their numerous size‐dependent optoelectronic behavior and promising materials applications . In particular, owing to the tunable and bright fluorescence, biocompatibility, and metal binding capabilities,,, we have a growing interest in the development of these π‐rich macrocycles for biological applications.…”

“…While a more detailed investigation of the scope is ongoing, for our work presented herein, we viewed [2]rotaxane 9 b as a particularly versatile intermediate. For example, motivated by our recent report on the biocompatibility of nanohoops as well the emerging interest in using fluorescent rotaxane architectures in biological environments, 9 b was saponified to access water‐soluble [2]rotaxane 9 c (Figure a), which retained the corresponding emission properties ( Φ =0.07) in aqueous conditions. Additionally, apart from biological systems, carboxylate functionalized [2]rotaxanes have also recently been incorporated into metal–organic frameworks, suggesting that this intermediate could act as a new π‐rich building block for unusual types of coordination polymers.…”