Space specific or stereoselective reactions in the limited nano -spaces

1. Space specific or stereoselective reactions in the limited nano-spaces Tobe laboratory ShintaroItano

2. Contents • What is Chemical Reaction? • Reaction Rate • Reaction in Enzyme pocket • Constitutional Isomer • Two-Dimensional Molecular Network • My Project • Conclusion

3. What is Chemical Reaction? • Chemical reaction A natural process in which the atoms of chemicals mix and arrange themselves differently to from new substances. A + B → C A + B→ C

4. Reaction Rate Reaction rate depends on the concentration of reactants. r = Aexp(-Ea/RT)[A][B] A = Frequency factor, Ea = Activation energy, R = Gas constant, T = Temperature, [A],[B] = Concentration of substrates

5. Reaction Rate E Ea1 Ea1 Ea2 Ea1＞ Ea2 T1＜ T2 Reaction rate depends on activation energy. r = Aexp(-Ea/RT)[A][B] A = Frequency factor, Ea = Activation energy, R = Gas constant, T = Temperature, [A],[B] = Concentration of substrates

6. Reaction in Enzyme Pocket Enzyme Close-up of the enzyme’s pocket

7. Reaction in Enzyme pocket Enzyme Close-up of the enzyme’s pocket

8. Space Specific Reaction Azide Room temperature Acetylene Kolb, H. C. et al. J. Am. Chem. Soc.2004, 128, 12809-12818.

9. Constitutional Isomer • Constitutional isomer (構造異性体) • Compounds that have identical molecular formulas but differ in the order in which the individual atoms are connected. • (VOLLHARDT SCHORE ORGANIC CHEMISTRY 5th Edition P169) Constitutional isomer (Chemical formula:C6H5O3N) Major compound

10. Two Dimensional (2D) Molecular Network Molecule (0.5~5 nm) • Self-assembly (自己集合) • The behavior that substrates create architecture by the interaction of themselves. • Two Dimensional Molecular Network • The network of molecules on solid surfaces base on self-assembly. • It formed by interactions such as van derwaals interactions and hydrogen-bond. Self-Assembly Construction of porous two-dimensioned molecular network on solid surfaces

11. Porous 2D Molecular network Dehydrobenzo[12]annulene (DBA) Model of honeycomb structure formed by DBA. Honeycomb structure De Feyter, S.; Tobe, Y. et. al. J. Am. Chem. Soc.2006, 128, 16613. Tobe, Y.; De Feyter. S. et al. Angew. Chem. Int. Ed. 2008,47, 2964.

12. Host-Guest Architecture between DBA and Nanographene = DBA Nanographene = Figure. (a) and (b) STM images of host-guest architecture formed by DBA and nanographene at the 1,2,4-trichlorobenzene/graphite interface. (c) A schematic model of honeycomb structure of DBA with nanographene. Tobe, Y.; De Feyter, S. et al. J. Am. Chem. Soc.2008, 130, 7119-7129.

13. My Project Reaction Guest molecules A molecule forming honeycombstructure

14. Conclusion • Reaction rates depend on the concentration of reactants and the amount of activation energy. • In the limited nano-space, reaction is significantly accelerated due to the increase of the collision frequency by capturing of the substrates. • in the space, reactions may proceed stereoselectively because of limit substrate conformation. • Accurate designing of molecules enable the construction of porous two-dimensioned molecular network on solid surfaces base on self-assembly.