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Contents
2
• Graphene
• Self-assembly of Molecules
• My Work
• Graphene
• Self-assembly of Molecules
• My Work
Graphene
4
Graphene
Graphene was isolated by using adhesive tape.
Novoselov and Geim won the Nobel Prize in 2010.
Novoselov, K. S. et al. Science 2004, 306, 666-669.
Graphene
5
Zboril, R. et al. Chem. Rev. 2012, 112, 6156−6214.
Properties of Graphene ・ Strength
・ Zero Band Gap
・ Ultrahigh Carrier Mobility
New MaterialTouch ScreensSensorSolar Cell
6
Chemical Modification (化学修飾 ) of Graphene
・ Changing double bonding of graphene to single bonding
double bonding : strong bondingsingle bonding : weak bonding
Carbon having double bonding : conductiveCarbon having no double bonding : non-conductive
We can control strength and conductivity of graphene
・ Adding molecule having useful properties to grapheneR
or R = molecule
H R
We can add useful property to graphene
Graphene Oxide酸化グラフェン R = Cl, NO2, OCH3, Br
1. N2H4 ・ H2O, pH 1080 ゜ C, 24 h
2. , rt, 1 hR N2+ BF4
-
Example of Chemical Modification of Graphene
7
Tour, J. M. et al. J. Am. Chem. Soc. 2008, 130, 16201-16206.
←Photographs of supernatant N,N′-dimethylformamide (DMF) solutions (上澄み ) obtained from dispersions of (a) graphene and (b) R = Br, (c) R = Cl, (d) R = NO2, and (e) R = OCH3 after centrifugation (遠心分離 ) for 15 min at 3200 rpm
Graphene modified can be dispersed (溶ける ) in polar solvent such as N,N′-dimethylformamide (DMF)
Functionalization With Diazirine of Graphene
R R'
N N hv
-N2
R R'R''
R R'
R''
Diazirine
CarbeneAddition
High Reactivity
TEM Image of Functionalized Graphene
Workentin, M. S. et al. Langmuir 2011, 27, 13261–13268.8
Carbene Addition
(付加反応 )
(高反応性 )
9
Problem of Chemical Modification of Graphene
Non-regular modification
We can’t precisely control the property
Regular modification is needed to control precisely the property
Construction of Nano Structure on Surfaces
= molecules
= substrate
= photoresist
= substrate
light
Top-down approach (photolithography)
Bottom-up approach (molecular self-assembly)
Self-assembly
About 100 nm scale 1~10 nm scale11
STM
13
Tip
Sample
electron
Tunneling current
Tip
Sample Small change
d (distance)
Ji (tunneling current)
Large change
Ji = Aexp(-Bd)
Ji : tunneling currentA, B : constantd : distance
14
O OH
OHO
O OH
Lackinger, M.; Griessl, S.; Heckl, W. M.; Hietschold, M.;Flynn, G. W.; Langmuir, 2005, 21, 4984.
Example of 2D Molecular Self-assembly
STM Image of 2D Molecular Self-assemblyat Alkanoic Acids/Graphite Interface
STM Image of DBA on Graphite
Honeycomb Structure of Dehydrobenzo[12]annulene (DBA) at the Liquid/Graphite Interface
O O
O
OO
O
=
15
DBA
Self-Assembly at the Liquid/Solid Interface
Honeycomb Structure of Dehydrobenzo[12]annulene (DBA) at the Liquid/Solid Interface
C12H25O OC12H25
OC12H25
OC12H25C12H25O
C12H25O
=
16
Van der Waals Forcebetween the Molecules
Van der Waals Forcebetween the Molecules and the Solid
DBA
Self-Assembly at the Liquid/Solid Interface
Honeycomb Structure of Dehydrobenzo[12]annulene (DBA) at the Liquid/Graphene Interface
C12H25O OC12H25
OC12H25
OC12H25C12H25O
C12H25O
=
17
STM Image of DBA on Single-Layer Graphene on Cu
DBA
Characters of DBA
R
R R
R
DBAOC10: R = OC10H21DBAOC12: R = OC12H25DBAOC14: R = OC24H29DBAOC16: R = OC16H33DBAOC18: R = OC18H37DBAOC20: R = OC20H41
R
R
DBA
=
• We can change the size of DBA and holes
• Holes catch the another molecules
Sensor18
Purpose of My Work
• Chemical stability of diazirine• Precursor of carbene• Photo-reaction under long wavelength
Diazirine
C14H29O OR
OC14H29
ORC14H29O
RO
R = (CH2)10OCF3
NN
DBA 1
C14H29O OR
OC14H29
ORC14H29O
RO
R = (CH2)10OCF3
DBA 1
hv
350 nmDiazirine Carbene
R R'
Y H
R''
R R'
R R'
Y H
R''
• High reactivity• Labeling of biomolecules• Adding to graphene
Carbene
Purpose of My Work
=
21
Diazirine
Graphene
Self-Assembly
C14H29O OR
OC14H29
ORC14H29O
RO
R = (CH2)10OCF3
NN
DBA 1
STM Image of DBA at the Phenyl Octane/Graphite Interface
24
7.2 × 10-7 mol/LSTM Image of DBA 1
on Graphite
Solvent : phenyloctane
C14H29O OR
OC14H29
ORC14H29O
RO
R = (CH2)10OCF3
NN
DBA 1
Summary
25
• Graphene is considered as a prospective material because of its unique properties.
• Chemical modification is used to control the properties of graphene and functionalize it
• Self-assembly by non-covalent interactions is used to construct the ordered structures at the solid surface.
• A purpose of my work is to establish an unique approach which makes periodic functionalization of graphene possible based on self-assemblies of molecules at the liquid/graphene interface and following the addition to the graphene.