Lecture 8 supramolecular chemistry

Nanochemistry NAN 601  Instructor:  Dr Marinella Sandros Lecture 8: Supramolecular Chemistr “Supramolecular chemistry is the chemistry of the intermolecular bond, covering the structures and functions of the entities formed by the association of two or more chemical species” J.-M- Lehn "Supramolecular chemistry is defined as chemistry ‘beyond the Molecule’, as chemistry of tailor shaped inter-molecular interaction.” F Vögtle http://www.waltry.f2s.com/lectures/supra-  “Chemistry beyond the molecule”  “Chemistry of molecular assemblies and of the intermolecular bond.”  “The Chemistry of non-covalent bond.”  Supramolecular chemistry involves investigating molecular systems in which the most important feature is that components are held together by intermolecular forces, not by covalent bonds Covalent Interactions Atoms Molecules Molecules Non-Covalent Interactions Supermolecules http://www.tfp.uni-karlsruhe.de/Summerschool/Lectures/voegtle1.pdf  Where did it come from? Inspired from biology and built on the shoulders of traditional synthetic organic chemistry  Why does it deserve to be a field of study all its own? The next logical step in synthetic chemistry; understanding and interface with the biological world; nanotechnology http://www.waltry.f2s.com/lectures/supra- http://www.waltry.f2s.com/lectures/supra- http://www.waltry.f2s.com/lectures/supra- Lock and Key Principle http://www.waltry.f2s.com/lectures/supra-  Two donor atoms linked together = a chelate (claw)  Chelate ligands form much more stable metal complexes than monodentate related ligands (up to 105 times as stable) Ni2+ + L Formation Constants: better L = NH3 en trien 2,3,2 complementarity 8.12 13.54 13.8 16.4 faculty.swosu.edu/tim.hubin/InorganicLects/InorgCh1 Why is favorable?? Thermodynamic Reasons for the Chelate Effect = Entropy 33 Macrocyclic chelate complexes are up 107 times more stable than non-cyclic chelates with the same number of donors Ni(trien)2+ Ni(cyclam)2+ years + H+ + H+ Ni2+ + H4trien4+ t½ = second Ni2+ + H4cyclam4+ t½ =  Connecting all of the donors (having no end group) makes k-2 important  Breaking the first M—L bond requires major ligand deformation  The increase in Ea required greatly slows down k-2 faculty.swosu.edu/tim.hubin/InorganicLects/InorgCh12.2.ppt • The result is a very stable complex as k d becomes miniscule 35 http://www.waltry.f2s.com/lectures/supra- http://www.waltry.f2s.com/lectures/supra- http://www.ciam.unibo.it/photochem/Ri.mo_03.pdf 38  They allow access to nanoscale objects using a bottom-up approach in far fewer steps than a single molecule of similar dimensions  The process by which a supramolecular assembly forms is called molecular self-assembly Some try to distinguish self-assembly as the process by which individual molecules form the defined aggregate Self-organization, then, is the process by which those aggregates create higher-order structures http://en.wikipedia.org/wiki/Supramolecular_assembly http://www.ciam.unibo.it/photochem/Ri.mo_03.pdf 40 http://www.ciam.unibo.it/photochem/Ri.mo_03.pdf 41 http://www.ciam.unibo.it/photochem/Ri.mo_03.pdf 42 http://www.esonn.fr/0oldweb/ESONN04/Lectures/esonn_2004_Mascini http://www.google.com/search?client=safari&rls=en&q=molecular+imprinting+ppt&ie=UTF 46 [...]... for supramolecular research http://en.wikipedia.org/wiki /Supramolecular_ chemistry 21 http://www.waltry.f2s.com/lectures/supra- people.bio.aau.dk/ /PowerPoint /Supramolecular% 2 0chemistry. ppt malina.ichf.edu.pl/educ/ /WYKLAD_SUPRA_NANO1_2005.ppt 24 http://www.waltry.f2s.com/lectures/supra- http://www.waltry.f2s.com/lectures/supra- http://www.waltry.f2s.com/lectures/supra- http://www.waltry.f2s.com/lectures/supra-... contains a discrete number of subunits 11 http://www.waltry.f2s.com/lectures/supra- http://www.waltry.f2s.com/lectures/supra-lec2.pdf12 13 14 http://www.waltry.f2s.com/lectures/supra-lec2.pdf http://www.waltry.f2s.com/lectures/supra- http://www.waltry.f2s.com/lectures/supra- http://www.waltry.f2s.com/lectures/supra- http://www.waltry.f2s.com/lectures/supra-  The study of non-covalent interactions is crucial... http://www.waltry.f2s.com/lectures/supra- http://www.waltry.f2s.com/lectures/supra- http://www.waltry.f2s.com/lectures/supra-  Two donor atoms linked together = a chelate (claw)  Chelate ligands form much more stable metal complexes than monodentate related ligands (up to 105 times as stable) Ni2+ + L Formation Constants: better L = NH3 en trien 2,3,2 complementarity 8. 12 13.54 13 .8 16.4 faculty.swosu.edu/tim.hubin/InorganicLects/InorgCh1... The increase in Ea required greatly slows down k-2 faculty.swosu.edu/tim.hubin/InorganicLects/InorgCh12.2.ppt • The result is a very stable complex as k d becomes miniscule 35 http://www.waltry.f2s.com/lectures/supra-