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Nanochemistry NAN 601 Instructor: Dr. Marinella Sandros Lecture 8: Supramolecular Chemistry 1 “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-lec1.pdf “Chemistry beyond the molecule” “Chemistry of molecular assemblies and of the intermolecular bond.” “The Chemistry of non-covalent bond.” 3 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. Atoms Molecules Covalent Interactions Non-Covalent Interactions Molecules Supermolecules 4 http://www.tfp.uni-karlsruhe.de/Summerschool/Lectures/voegtle1.pdf 5 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 6 http://www.waltry.f2s.com/lectures/supra-lec1.pdf http://www.waltry.f2s.com/lectures/supra-lec1.pdf http://www.waltry.f2s.com/lectures/supra-lec1.pdf Lock and Key Principle http://www.waltry.f2s.com/lectures/supra-lec2.pdf Molecular Self-Assembly: Process by which 2 or more molecules interact from a larger structure or organization. Super-Molecule: A complex formed by molecular selfassembly which contains a discrete number of subunits. 11 http://www.waltry.f2s.com/lectures/supra-lec2.pdf http://www.waltry.f2s.com/lectures/supra-lec2.pdf 12 13 14 http://www.waltry.f2s.com/lectures/supra-lec2.pdf http://www.waltry.f2s.com/lectures/supra-lec2.pdf http://www.waltry.f2s.com/lectures/supra-lec2.pdf http://www.waltry.f2s.com/lectures/supra-lec2.pdf http://www.waltry.f2s.com/lectures/supra-lec2.pdf The study of non-covalent interactions is crucial to understanding many biological processes from cell structure to vision that rely on these forces for structure and function. Biological systems are often the inspiration for supramolecular research. http://en.wikipedia.org/wiki/Supramolecular_chemistry 21 http://www.waltry.f2s.com/lectures/supra-lec1.pdf people.bio.aau.dk/.../PowerPoint/Supramolecular%20chemistry.ppt malina.ichf.edu.pl/educ/.../WYKLAD_SUPRA_NANO1_2005.ppt 24 http://www.waltry.f2s.com/lectures/supra-lec1.pdf http://www.waltry.f2s.com/lectures/supra-lec1.pdf http://www.waltry.f2s.com/lectures/supra-lec1.pdf http://www.waltry.f2s.com/lectures/supra-lec1.pdf http://www.waltry.f2s.com/lectures/supra-lec1.pdf http://www.waltry.f2s.com/lectures/supra-lec1.pdf http://www.waltry.f2s.com/lectures/supra-lec1.pdf 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: L = NH3 en trien 2,3,2 8.12 13.54 13.8 16.4 better complementarity faculty.swosu.edu/tim.hubin/InorganicLects/InorgCh12.2.ppt 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+ H+ + Ni2+ + H4trien4+ H+ t½ = 2 seconds Ni2+ + H4cyclam4+ t½ = 2 years 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 kd becomes miniscule 35 http://www.waltry.f2s.com/lectures/supra-lec1.pdf http://www.waltry.f2s.com/lectures/supra-lec1.pdf 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_Mascini3.pdf http://www.google.com/search?client=safari&rls=en&q=molecular+imprinting+ppt&ie=UTF-8&oe=UTF-8 46