Ting Chen, Qing Chen, Xu Zhang, Dong Wang, Li-jun Wan

1. Chiral Kagomé Network from Thiacalix[4]arene Tetrasulfonate at the Interface of Aqueous/Au(111) Surface: An in Situ Electrochemical Scanning Tunneling Microscopy Study Ting Chen, Qing Chen, Xu Zhang, Dong Wang, Li-jun Wan J. Am. Chem. Soc.2010, 132, 5598-5599 2010/12/1 Tobe lab. Yamaga Hiroyuki

2. Contents ・Introduction Self-assembly on two-dimensional surface Intermolecular interaction Scanning tunneling microscope (STM) Two-dimensional chirality ・Result and discussion Kagomé network Calixarene Thiacalix[4]arene tetrasulfonate (TCAS) STM observation Chirality of the Kagome Network Formed by TCAS ・Summary

3. Self-Assembly on Two-Dimensional Surface Self-assembly Self-assembly is the spontaneousorganization of molecular units into ordered structures by non-covalent interactions. Self-Assembly Non-porous network Porous network application ·Pattern formation in few nanometer-scale ·Molecular electronics and data storage device In these fields, scanning tunneling microscope (STM) is very useful tool.

4. electron Tunneling current Scanning Tunneling Microscope (STM) STM is a powerful instrument for imaging surfaces at the atomic level. Tip Tunneling current Sample Schematic view of STM

5. Scanning Tunneling Microscope (STM) Ji (tunneling current) Ji = Aexp(-Bd) Largechange Ji : tunneling current A, B : constant d : distance d (distance) Smallchange Tip Sample

6. Intermolecular Interaction -Hydrogen Bond- Hydrogen bond (水素結合) High boiling point! Chickenwire structure Lackinger, M.; Griessl, S.; Heckl, W. M.; Hietschold, M.; Flynn, G. W.; Langmuir, 2005, 21, 4984.

7. Intermolecular Interaction-Van der Waals Interaction- Van der Waals interaction Weak intermolecular force acting between the neutral molecules or atoms like polyethylene. Interdigitation (組み合い) Bléger, D.; Kreher, D.; Mathevet, F.; Attias, A.-J.; Schull, G.; Huard, A.; Douillard, L.; Fiorini-Debuischert, C.; Charra, F. Angew. Chem. Int. Ed. 2007, 46, 7404–7407. Another interactions Metal-ligand interaction, dipole-dipole interaction etc

8. Purpose of This Work A chiral Kagomé network was fabricated at an aqueous solution/Au(111) interface by using thiacalix[4]arene tetrasulfonate (TCAS) as a building block. Kagomé Network 2D Kagomé network is interesting because it contains triangular and hexagonal voids (空孔) which can serve as a site-selective template for guest molecules

9. Kagomé Network Triphenylene Bis-DBA Isophthalic acid Coronene STM image of a mixture of bisDBA-C12 (3.8  10-6 M), COR(4.5  10-4 M), ISA (2.5  10-3 M), and TRI (6.0  10-4 M). Adisoejoso, J.; Tahara, K.; Okuhata, S.; Lei, S.; Tobe, Y.; De Feyter, S. Angew. Chem. Int. Ed. 2009, 121, 7489–7493.

10. Thiacalix[4]arene Tetrasulfonate (TCAS) Calixarene Calixarenes are cup shapemolecule having hydrophobic cavities. Calixarenepossess a good complexing ability to guest molecules. Calix[4]arene Thiacalix[4]arene Tetrasulfonate Interesting functions It can form fascinating supramolecular structures in the presence of suitable guest molecules.

11. STM Observation A well-ordered nanoporous array was clearly observed. Diameter of the pore ~ 1.4 nm Pore to pore distance ~ 3.6 nm Unit cell parameters a=b=3.6 0.1 nm a=60° STM image of TCAS adlayer on Au(111) surface. Esub = 550 mV, Ebias = -493 mV, I = 823 pA

12. STM Observation The buildingblock of the network is a set of two bright spots (red rod). Every three sets of spots arrange triangularly, whereas six triangles enclose a regular hexagon in a vertex-sharing manner, as illustrated by white lines. This arrangement is a 2D Kagomé structure. STM image of TCAS adlayer on Au(111) surface. Esub = 550 mV, Ebias = -415 mV, I = 299 pA

13. STM Observation Each building block was imaged as a set of four spots with different contrast. The size of each spot is equal to that of the phenyl. The different contrast of phenyls is attributed to the different orientation of phenyls on Au(111) surface. Phenyl STM image of TCAS adlayer on Au(111) surface. Esub = 550 mV, Ebias = -605 mV, I = 580 pA

14. STM Observation TCAS molecules are supposed to adsorb on the substrate in an upside-down manner. (The sulfonate groups interact with the surface whereas the hydroxyls point to the solution). Au(111) surface No directional intermolecular interaction exists. TCAS molecules interact through a nonspecific van der Waals force and form the Kagomé network.

15. Two-dimensionalChirality Chirality A property of molecules having a non-superimposable mirror image. Two-Dimensional (2D) Chirality Crop circles at air/farmland interface

16. Chiralityof the Kagomé Network Formed by TCAS Mirror Two domainsare contained in the STM image. The chirality of the network should originate from the molecular assembly. There is a small off angle d. STM image of TCAS adlayer on Au(111) surface. Esub = 550 mV, Ebias = -666 mV, I = 899 pA

17. Summary • The formation of a chiral Kagome network structure using TCAS which is a structure-complicated supramolecule calixarene as a building block at an aqueous/Au(111) interface have been demonstrated. • The possibility to construct a 2D nanoporous network by variousfunctional supramolecules is opened. • Thanks to the versatility of TCAS,a plethora of host-guest complexes could be integrated into the Kagome network. • The construction of a chiral cavity array in aqueous media would facilitate single molecular recognition with biological active chiral molecules.

19. Synthesis of TCAS Morohashi, N.; Narumi, F.; Iki, N.; Hattori, T.; Miyano, S. Chem. Rev.2006, 106, 5291–5316.

20. Au Surface

21. STMImage

22. Calixarene Haino, T.; Matsumoto, Y.; Fukazawa, Y. J. Am. Chem. Soc. 2005, 127, 8936–8937.