Minisymposium Dynamická kovalentní chemie: Hranice a perspektivy

KDY:    čtvrtek 27. 6. 2019, od 9:00 do 12:20
KDE:    Ústav fyzikální chemie J.Heyrovského, Brdičkova posluchárna, Dolejškova 2155/3, Praha 8

kontaktní osoba: Dr. Petr Kovaříček, petr.kovaricek@jh-inst.cas.cz

PROGRAM:

9:00 – 10:15

 “Perspectives in Chemistry: Towards Adaptive Chemistry”
Prof. Jean-Marie Lehn, ISIS, Université de Strasbourg, France

Coffee break

10:30 – 11:00 

 „Diversions and junctions in the road of science: from carbon nanotube rotaxanes to covalent organic frameworks“
Prof. Emilio Pérez Álvarez, IMDEA Nanoscience, Madrid, Spain

11:10 – 11:40 
„Manipulating the Monolayer: Dynamic Covalent Nanoparticle Building Blocks“
Prof. Euan Kay, School of Chemistry, University of St. Andrews, United Kingdom 

11:50 – 12:20
 „New Tools and Uses of Dynamic Covalent Chemistry“
Prof. Max von Delius, Institute of Organic Chemistry and Advanced Materials, University of Ulm, Germany

Perspectives in Chemistry: Towards Adaptive Chemistry
 Supramolecular chemistry is intrinsically a dynamic chemistry in view of the lability of the interactions connecting the molecular components of a supramolecular entity and the resulting ability of supramolecular species to exchange their components. Similarly, molecular chemistry becomes a dynamic covalent chemistry (DCC) on introduction into the molecular entity of covalent bonds that may form and break reversibly, so as to allow a continuous change in constitution by reorganization and exchange of building blocks. Taken together, these features define a Constitutional Dynamic Chemistry (CDC) covering both the molecular and supramolecular levels. CDC introduces a paradigm shift with respect to constitutionally static chemistry. It takes advantage of dynamic diversity to allow variation and selection and operates on dynamic constitutional diversity in response to either internal or external factors to achieve adaptation. CDC generates networks of dynamically interconverting constituents, constitutional dynamic networks, presenting agonistic and antagonistic relationships between their constituents that may respond to perturbations by physical stimuli or to chemical effectors. It applies in chemistry as well as in materials science. The implementation of these concepts points to the emergence of adaptive and evolutive chemistry, towards systems of increasing complexity. 
 

 „Diversions and junctions in the road of science: from carbon nanotube rotaxanes to covalent organic frameworks“
It is both obvious and often forgotten that science is made by scientists. Chemistry has the privilege of creating its own matter of study, and therefore is perhaps the branch of science where creativity is most important. It follows that the outcome of a chemistry project is heavily influenced by the personality, abilities and interests of the chemist at the bench. In this presentation, I will describe how our initial plan to make carbon nanotube-rotaxanes1 with pyrene decorated macrocycles eventually diverted into projects in catalysis,2 supramolecular chemistry,3, 4 polymer chemistry,5 and covalent organic frameworks,6, 7 always while advancing towards our initial goal.8-10 Of course, not all diversions lead to nice places, and I will also describe the time spent re-descovering chemistry that had been known for decades! 11 It is the story of the inspiration and perspiration that led Alejandro to a remarkably successful PhD, and the whole group to get involved in new and exciting collaborations. 
 

Manipulating the Monolayer: Dynamic Covalent Nanoparticle Building Blocks
Monolayer-stabilized nanoparticles are a canonical category of nanomaterial that exhibit a range of potentially useful properties depending on the material composition. Colloidal stability allows nanomaterials of this sort to be manipulated in solution in much the same way as (macro)molecular systems. This raises the prospect of extending synthetic chemistry capabilities to include chemically active nanoscale components, which would be particularly attractive given that virtually every application of monolayer-stabilized nanoparticles requires optimization and interrogation of surfacebound chemical functionality. Yet, robust approaches for nanomaterial surface engineering are critically under-developed.1 ‘Dynamic covalent nanoparticle (DCNP) building blocks’ introduce a conceptually distinct strategy for post-synthetic modification of nanoparticle-bound molecules, essentially independent of the underlying nanomaterial. Combining the error-correcting and stimuli-responsive features of equilibrium processes with the stability and vast structural diversity of covalent chemistry enables efficient, divergent routes to myriad functionalized nanomaterial products. Here I will introduce the DCNP concept using the example of hydrazone exchange within gold nanoparticle-bound monolayers; I will discuss the role that monolayer-stabilized nanoparticles can play as ‘pseudomolecular’ models for surface-confined chemical processes; and I will demonstrate how understanding the molecular-level details of surface-bound reactions helps us to predictably modify nanoparticle surface chemistry, to tune nanoparticle properties, or to direct selective covalent assembly of specific nanoparticle building blocks.2–5 

New Tools and Uses of Dynamic Covalent Chemistry
Dynamic covalent chemistry (DCC) is a powerful tool for probing non-covalent interactions, identifying ligands for medicinally relevant biological targets, and for making use of the feature of “error correction” to achieve the synthesis of interesting molecules and materials.[1] In this talk, I will present our recent work on a previously ignored dynamic covalent reaction: the acid-catalyzed reaction of O,O,O-orthoesters with alcohols (Fig. a),[2a] which we were able to use for the one-pot synthesis of cryptates, in which orthoesters act as tripodal bridgeheads.[2b] Due to their unique structure (Fig. b), these compounds exhibit a range of unusual properties, including tunable, pHdependent hydrolysis (Fig. c). [2c] Most notably, dynamic orthoester architectures offer an elegant entry to experiments, in which a metal ion selects its preferred host from a dynamic mixture of competing subcomponents (“adaptive host-guest systems”, Fig. d).[2d] Of particular relevance to the area of systems chemistry is our recent discovery that ammonium complexes of orthoester cryptands represent the first example of “fluxional supermolecules”, i.e. these host-guest complexes are inherently dynamic and adaptive (Fig. e). [2e] I will close the talk by discussing unpublished work on “new” dynamic covalent reactions and their (potential) uses.