6 research outputs found
Gold(I)-Catalysed Direct Thioetherifications Using Allylic Alcohols: an Experimental and Computational Study
A gold(I)-catalysed direct thioetherification reaction between allylic alcohols and thiols is presented. The reaction is generally highly regioselective (S(N)2′). This dehydrative allylation procedure is very mild and atom economical, producing only water as the by-product and avoiding any unnecessary waste/steps associated with installing a leaving or activating group on the substrate. Computational studies are presented to gain insight into the mechanism of the reaction. Calculations indicate that the regioselectivity is under equilibrium control and is ultimately dictated by the thermodynamic stability of the products
Pathway-Controlled Aqueous Supramolecular Polymerization via Solvent-Dependent Chain Conformation Effects
Pathway Control in Cooperative vs. Anti-Cooperative Supramolecular Polymers
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Pathway control in cooperative vs. anti-cooperative supramolecular polymers
Controlling the nanoscale morphology in assemblies of π-conjugated molecules is key to developing supramolecular functional materials. Here, we report an unsymmetrically substituted amphiphilic PtII complex 1 that shows unique self-assembly behavior in nonpolar media, providing two competing anti-cooperative and cooperative pathways with distinct molecular arrangement (long- vs. medium-slipped, respectively) and nanoscale morphology (discs vs. fibers, respectively). With a thermodynamic model, we unravel the competition between the anti-cooperative and cooperative pathways: buffering of monomers into small-sized, anti-cooperative species affects the formation of elongated assemblies, which might open up new strategies for pathway control in self-assembly. Our findings reveal that side-chain immiscibility is an efficient method to control anti-cooperative assemblies and pathway complexity in general
Pathway-Controlled Aqueous Supramolecular Polymerization via Solvent-Dependent Chain Conformation Effects
Solute–solvent interactions play a critical role
in multiple
fields, including biology, materials science, and (physical) organic,
polymer, and supramolecular chemistry. Within the growing field of
supramolecular polymer science, these interactions have been recognized
as an important driving force for (entropically driven) intermolecular
association, particularly in aqueous media. However, to date, solute–solvent
effects remain poorly understood in the context of complex self-assembly
energy landscapes and pathway complexity. Herein, we unravel the role
of solute–solvent interactions in controlling chain conformation
effects, allowing energy landscape modulation and pathway selection
in aqueous supramolecular polymerization. To this end, we have designed
a series of oligo(phenylene ethynylene) (OPE)-based bolaamphiphilic
Pt(II) complexes OPE2–4 bearing solubilizing
triethylene glycol (TEG) chains of equal length on both molecule ends,
but a different size of the hydrophobic aromatic scaffold. Strikingly,
detailed self-assembly studies in aqueous media disclose a different
tendency of the TEG chains to fold back and enwrap the hydrophobic
molecular component depending on both the size of the core and the
volume fraction of the co-solvent (THF). The relatively small hydrophobic
component of OPE2 can be readily shielded by the TEG
chains, leading to only one aggregation pathway. In contrast, the
decreased capability of the TEG chains to effectively shield larger
hydrophobic cores (OPE3 and OPE4) enables
different types of solvent quality-dependent conformations (extended,
partly back-folded and back-folded), which in turn induce various
controllable aggregation pathways with distinct morphologies and mechanisms.
Our results shed light on previously underappreciated solvent-dependent
chain conformation effects and their role in governing pathway complexity
in aqueous media