After a brief introduction highlighting the challenges of fluorine chemistry and the latest developments in the field, this Perspective will discuss how a combination of fluorine and fluorous chemistry together with fluorinated reagents helped to bridge between organic, molecular, macromolecular, supramolecular and biological sciences to create functions in the laboratory of the corresponding author. The reactivity of fluoride as a leaving group is best illustrated by SNAr reactions when it helped to demonstrate single electron transfer-mediated side reactions and through molecular design replaced activated aryl fluorides with aryl chlorides in the synthesis of poly(etherketone)s. Subsequently it was demonstrated how Ni(II) sigma complexes provided an orthogonal approach to the Suzuki-type cross-coupling of arylfluorides, other halides and all aryl C–O based electrophiles. Fluorinated reagents facilitated cylotrimetrization vs cyclotetramerization of bis(methoxy)benzyl chloride and alcohol and the synthesis of the simplest molecular liquid crystals. Triflic acid, methyl triflate facilitated the most tolerant living polymerizations including of cyclic siloxanes, functional vinyl ethers and oxazolines to generate self-organizable dendronized polymers while fluorine, trifluoromethyl and trifluoromethoxy groups facilitated disassembly and reassembly of liquid crystal polyethers and poly(p-phenylenes). Fluorinated stereocenters accessed the first heterochiral recognition in side-chain liquid crystal poly(vinyl ether)s and their model compounds. Alkali metal triflates mediated self-organization of supramolecular nonfluorinated and fluorinated self-assembling minidendrons, dendrons, dendrimers and self-organizable dendronized polymers. The role of fluorinated alkyl groups and of alkali metal triflates in the self-assembly, disassembly and isomorphic replacement analysis, of supramolecular helical columns, of the assembly of helical cogwheel coat and of spherical supramolecular dendrimers forming Frank-Kasper periodic and quasiperiodic arrays was highlighted. A brief discussion of fluorinated amino acids, peptides and peptoids and their potential role in the self-assembly and functions resulted from dendritic dipeptides followed by a discussion of semifluorinated amphiphilic Janus dendrimers as models of biological membranes, including for cell fusion and fission, concludes this Perspective.
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Stimuli-Responsive Principles of Supramolecular Organizations Emerging from Self-Assembling and Self-Organizable Dendrons, Dendrimers, and Dendronized Polymers
All activities of our daily life, of the nature surrounding us and of the entire society and its complex economic and political systems are affected by stimuli. Therefore, understanding stimuli-responsive principles in nature, biology, society, and in complex synthetic systems is fundamental to natural and life sciences. This invited Perspective attempts to organize, to the best of our knowledge, for the first time the stimuli-responsive principles of supramolecular organizations emerging from self-assembling and self-organizable dendrons, dendrimers, and dendronized polymers. Definitions of stimulus and stimuli from different fields of science are first discussed. Subsequently, we decided that supramolecular organizations of self-assembling and self-organizable dendrons, dendrimers, and dendronized polymers may fit best in the definition of stimuli from biology. After a brief historical introduction to the discovery and development of conventional and self-assembling and self-organizable dendrons, dendrimers, and dendronized polymers, a classification of stimuli-responsible principles as internal- and external-stimuli was made. Due to the enormous amount of literature on conventional dendrons, dendrimers, and dendronized polymers as well as on their self-assembling and self-organizable systems we decided to discuss stimuli-responsive principles only with examples from our laboratory. We apologize to all contributors to dendrimers and to the readers of this Perspective for this space-limited decision. Even after this decision, restrictions to a limited number of examples were required. In spite of this, we expect that this Perspective will provide a new way of thinking about stimuli in all fields of self-organized complex soft matter.
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- Award ID(s):
- 2104554
- PAR ID:
- 10411346
- Date Published:
- Journal Name:
- Polymers
- Volume:
- 15
- Issue:
- 8
- ISSN:
- 2073-4360
- Page Range / eLocation ID:
- 1832
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Homochiral helical self‐organizations provide some of the most fundamental architectures of biological macromolecules and of their co‐assemblies although they were first discovered and elucidated only during the early 1950. Helical synthetic covalent macromolecules started to be discovered soon after and were followed by supramolecular macromolecules and their co‐assemblies few decades later. This perspective will provide a brief historical development of chiral helical self‐organizations in biology and in supramolecular chemistry. Helical covalent and supramolecular macromolecules self‐organize and co‐organize helical supramolecular columns and spherical helices that can generate complex liquid crystals, crystals including Frank‐Kasper phases, and quasicrystals. The design of new functions based on synthetic helical assemblies will also be discussed. Personal events from the life of scientists contributing to these developments are also briefly mentioned.
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null (Ed.)Fundamental bacterial functions like quorum sensing can be targeted to replace conventional antibiotic therapies. Nanoparticles or vesicles that bind interfacially to charged biomolecules could be used to block quorum sensing pathways in bacteria. Towards this goal, dendronized vesicles (DVs) encompassing polyamidoamine dendron-grafted amphiphiles (PDAs) and dipalmitoyl- sn-glycero -3-phosphocholine lipids are investigated using the molecular dynamics simulation technique in conjunction with an explicit solvent coarse-grained force field. The key physical factors determining the stability of DVs as a function of the dendron generation and relative concentration are identified. The threshold concentration of each dendron generation that yields stable DVs is determined. Dendrons with lower generations rupture the DVs at high relative concentrations due to the electrostatic repulsions between the terminally protonated amines. Whereas, dendrons with intermediate generations demonstrate a mushroom-to-brush transition. Conformational changes in the dendrons expand the outer DV surface, resulting in instability in the DV bilayer. DVs encompassing dendrons with higher generations incur stresses on the bilayer due to their high charge density and spontaneous curvature. The self-organization of PDAs on the DV surface are examined to understand how the asymmetric stresses are minimized across the bilayer. A set of conditions are determined to be conducive for the formation of a single cluster of PDAs that decorates the DV surface like a mesh. Results from this study can potentially guide the design and synthesis of nanoparticles which target quorum sensing pathways in bacteria towards the prevention and treatment of bacterial infections. Furthermore, these nanoparticles can be used in diverse applications in biomedicine, energy or electronics that require synthetic dendronized cells or the adsorption and transport of charged species.more » « less
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In 2022, the Nobel Prize in Chemistry was awarded to Bertozzi, Meldal, and Sharpless “for the development of click chemistry and biorthogonal chemistry”. Since 2001, when the concept of click chemistry was advanced by Sharpless laboratory, synthetic chemists started to envision click reactions as the preferred choice of synthetic methodology employed to create new functions. This brief perspective will summarize research performed in our laboratories with the classic Cu(I)-catalyzed azide-alkyne click (CuAAC) reaction elaborated by Meldal and Sharpless, with the thio-bromo click (TBC) and with the less-used, irreversible TERminator Multifunctional INItiator (TERMINI) dual click (TBC) reactions, the last two elaborated in our laboratory. These click reactions will be used to assemble, by accelerated modular-orthogonal methodologies, complex macromolecules and self-organizations of biological relevance. Self-assembling amphiphilic Janus dendrimers and Janus glycodendrimers together with their biological membrane mimics known as dendrimersomes and glycodendrimersomes as well as simple methodologies to assemble macromolecules with perfect and complex architecture such as dendrimers from commercial monomers and building blocks will be discussed. This perspective is dedicated to the 75th anniversary of Professor Bogdan C. Simionescu, the son of my (VP) Ph.D. mentor, Professor Cristofor I. Simionescu, who as his father, took both science and science administration in his hands, and dedicated his life to handling them in a tandem way, to their best.more » « less
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Abstract Recent advances of supramolecular chemistry utilized in the development of self‐healing polymers have revealed that the rate and equilibrium constants of bond dissociation/re‐association, bonding directionality, chain relaxation time, decay rate of chain relaxation after damage, and cluster formation may impact the healing efficiency in a given environment. This review provides an assessment of supramolecular chemistries responsible for self‐healing using H‐bonding, metal–ligand, host–guest, ionic, π–π, and hydrophobic interactions. The impact of these chemistries on self‐healing is examined for various polymeric systems with multifunctional applications which are unique to supramolecular networks. This review also discusses the driving forces leading to physical damage closure in the context of supramolecular bond dynamics, providing insights into the design principles to achieve efficient recovery.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3390/polym15081832
