An official website of the United States government
New routes to the formation of macrocyclic molecules are of high interest to the supramolecular chemistry community and the chemistry community at large. Here we describe the incorporation of heterocyclic core units into discrete macrocycles via the utilization of a pnictogen-assisted self-assembly technique. This method allows for the rapid and efficient formation of discreet macrocyclic units from simple dithiol precursors in high yields with good control over macrocycle size. Up to this point, this technique has been reported on primarily benzylic thiol systems with very little incorporation of endohedral heteroatoms in the resulting assemblies. This study demonstrates the effective incorporation of heterocyclic core molecules allowing for the formation of a more functional cavity, resulting in the formation and crystallization of novel furan- and thiophene-based disulfide dimer and trimer macrocycles, respectively, that are isolated from a range of other larger discrete macrocycles that assemble as well. These disulfide macrocycles can be trapped as their more kinetically stable thioether congeners upon sulfur extrusion.
more »
« less
Pnictogen‐Assisted Self‐Assembly as a Means to Study Mediated Thiol/Disulfide Exchange in Supramolecular Dynamic Covalent Assemblies
Abstract Thiol‐disulfide interchange has been a large field of study for both biochemists and physical organic chemists alike due to its prevalence within biological systems and fundamentally interesting dynamic nature. More recently, efforts have been made to harness the power of this reversible reaction to make self‐assembling systems of macrocyclic molecules. However, less effort has focused on the fundamental work of isolating these assemblies and studying the factors that control the assembly and sorting of these emerging cyclic systems. A more complete fundamental understanding of factors controlling such self‐assembly could also improve understanding of the complex systems biology of thiol exchange while also aiding in the design of dynamic thiol assembly to enable applications ranging from drug delivery and biosensing to new materials synthesis. We have shown previously that pnictogen‐assisted self‐assembly enables formation of discrete disulfide macrocycles and cages without competition from polymer formation for a wide variety of alkyl thiols. In this study, we report the expansion of pnictogen‐assisted self‐assembly methods to form disulfide bearing macrocycles from aryl thiol containing ligands, allowing access to previously unreported molecules. These studies complement classical physical organic and chemical biology studies on the rates and products of aryl thiol oxidation to disulfides, and we show that this self‐assembly method revises some prevailing wisdom from these key classical studies by providing new product distributions and new isolable products in cyclic disulfide formation.
more »
« less
- Award ID(s):
- 2003928
- PAR ID:
- 10642314
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Chemistry – A European Journal
- Volume:
- 30
- Issue:
- 67
- ISSN:
- 0947-6539
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Disulfide hydrogels, derived from cysteine‐based redox systems, exhibit active self‐assembly properties driven by reversible disulfide bond formation, making them a versatile platform for dynamic material design. Detailed cryogenic electron microscopy (cryo‐EM) analysis reveals a consistent fiber diameter of 5.4 nm for individual fibers. Using cryo‐EM‐informed radial positional restraints, all‐atom molecular dynamics (MD) simulations are employed to reproduce fibers with dimensions closely matching experimental observations, validated further through simulated cryo‐EM images. The MD simulations reveal that the disulfide gelator (CSSC) predominantly adopts an open conformation, with hydrogen bonds emerging as the key intermolecular force stabilizing the fibers. Notably, intermolecular interactions are found to be higher at 70% conversion to the disulfide gelator compared with 100%, comparable with past unrestrained simulations. Water molecules and solute‐water hydrogen bonds are present throughout the fiber, indicating that the fiber remains hydrated. These findings underscore the potential role of the thiol precursor CSH in stabilizing the transient phase and highlight the importance of CSH‐CSSC interplay. Herein, it provides novel insights into molecular mechanisms governing active self‐assembly and offers strategies for designing tunable materials through controlled assembly conditions.more » « less
-
Abstract This work reports the synthesis and self‐assembly of perylene diimide (PDI)‐containing macrocycles designed for facile and high‐throughput production of shape‐persistent, macrocyclic organic electronic materials. Specifically, utilizing dynamic covalent chemistry (DCvC), this work showcases ditopic thiols can be utilized as building blocks toward 3D materials with defined porosity, low‐lying unoccupied molecular orbitals, and intrinsic fluorescence. The PDI disulfide‐linked macrocycles are generated in a single step from the thiolic building block to yield dimeric through pentameric assemblies in overall 95% combined yield; moreover, following self‐assembly, the disulfide ensemble is sulfur extruded to the more kinetically stable thioether in 79% combined yield. The modular design suggests these methods can be used to easily self‐assemble other electronically active precursors for utility in porous macrocyclic materials where stepwise pathways may be laborious and/or low yielding.more » « less
-
Abstract Cyclophanes are a fundamentally interesting class of compounds that host a wide range of unique and emergent properties. However, synthesis of complex and/or functionalized cyclophanes can often suffer from harsh reaction conditions, long reaction times, and sometimes low yields using stepwise methods. We have previously reported an efficient, high‐yielding, metalloid‐directed self‐assembly method to prepare disulfide, thioether, and hydrocarbon cyclophanes and cages that feature mercaptomethyl‐arenes as starting materials. Herein, we report the synthesis of 21 new disulfide and thioether assemblies that expand this high yielding self‐assembly method to a wide breadth of macrocycles and cages with diverse structures. Remarkably, the high‐yielding, efficient syntheses still proceed under dynamic covalent control using electron‐deficient, heteroaryl, cycloalkyl, spiro, and even short alkenyl/alkynyl substrates.more » « less
-
A new air and moisture stable antimony thiolate compound has been prepared that spontaneously forms stable hollow vesicles. Structural data reveals that pnictogen bonding drives the self-assembly of these molecules into a reversed bilayer. The ability to make these hollow, spherical, and chemically and temporally stable vesicles that can be broken and reformed by sonication allows these systems to be used for encapsulation and compartmentalisation in organic media. This was demonstrated through the encapsulation and characterization of several small organic reporter molecules.more » « less
