スライド 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
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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
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Self-Assembly on Two-Dimensional Surface
Self-assembly
Self-assembly is the spontaneous organization 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.
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Scanning Tunneling Microscope (STM)
STM is a powerful instrument for imaging surfaces at the atomic level.
electron
Tip
Tunneling
current
Sample
Tunneling
current
Schematic view of STM
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Scanning Tunneling Microscope (STM)
Ji (tunneling current)
Ji = Aexp(-Bd)
Large change
Ji : tunneling current
A, B : constant
d : distance
d (distance)
Small change
Tip
Sample
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Intermolecular Interaction
-Hydrogen BondHydrogen bond (水素結合)
High boiling point!
Chickenwire structure
Lackinger, M.; Griessl, S.; Heckl, W. M.;
Hietschold, M.; Flynn, G. W.; Langmuir,
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2005, 21, 4984.
Intermolecular Interaction
-Van der Waals InteractionVan der Waals interaction
Weak intermolecular force acting between the
neutral molecules or atoms like polyethylene.
Interdigitation (組み合い)
Another interactions
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.
Metal-ligand interaction, dipole-dipole interaction etc
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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
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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.
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Thiacalix[4]arene Tetrasulfonate (TCAS)
Calixarene
Calixarenes are cup shape molecule having
hydrophobic cavities.
Calixarene possess 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.
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STM Observation
A well-ordered nanoporous array was
clearly observed.
Diameter of the pore
Pore to pore distance
Unit cell parameters
a=b=3.6  0.1 nm
STM image of TCAS adlayer on Au(111) surface.
Esub = 550 mV, Ebias = -493 mV, I = 823 pA
~ 1.4 nm
~ 3.6 nm
a=60°
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STM Observation
The building block 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
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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
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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.
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Two-dimensional Chirality
Chirality
A property of molecules having a non-superimposable mirror image.
Two-Dimensional (2D) Chirality
Crop circles at air/farmland interface
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Chirality of the Kagomé Network Formed by TCAS
Mirror
Two domains are 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
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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 various
functional 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.
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Synthesis of TCAS
Morohashi, N.; Narumi, F.; Iki, N.; Hattori, T.; Miyano, S. Chem. Rev. 2006, 106, 5291–5316.
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Au Surface
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STM Image
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Calixarene
Haino, T.; Matsumoto, Y.; Fukazawa, Y. J. Am. Chem. Soc. 2005, 127, 8936–8937.
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