Synthesis of a Fluoreno[2,3-b]fluorene Derivative to

Experimentally Verify Extraordinary Optical Properties of

Indenofluorenes

Tobe Lab.Masahito Miki

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Contents

• Introduction Singlet biradicals

Resonance structures

Quinodimethanes

• Previous work　 Comparision of UV-vis-NIR spectra

　 p-conjugation space and absorption wave length

　 New Principle for Low Energy Absorption

　 Nonalternant hydrocarbons

　 Excitation energy of biradical compounds

• My work2

Singlet BiradicalsHOMO and LUMO of biradicaloids

y = 0Fabian, J. et al. Angew. Chem. Int. Ed. 1989, 28, 677.

closed shell singlet biradical open shell

y = 1

0 < y < 1

一重項ビラジカル 閉殻 開殻

HOMO

LUMO

UHF/6-31G*//UB3LYP/6-31G* and Yamaguchi schemeYamaguchi, K. Chem. Phys. Lett. 1975, 33,

330.

nHOMO, nLUMO; occupation numbers of HOMO or LUMO

21

21

T

Ty

2

LUMOHOMO nnTbiradical character :

3

Resonance Structures

Closed shell閉殻構造

Open shell開殻構造

・ All electrons are used to bonds.・ closed-shell

・ A bond is broken・ open-shell

Energy loss for breaking pbond (272 kJ / mol)

Aromatic stabilization energy芳香族安定化エネルギー(about 90 kJ / mol)

benzene

Unimportant contributor

Important contributor

4

Quinodimethanes (QDM)

R

RR = Si

Mes Mes

Mes =

Chase, D. T. et al. Angew. Chem. Int. Ed. 2011, 50, 11103.

Shimizu, A.; Tobe, Y. Angew. Chem. Int. Ed. 2011, 50, 6906.

o-quinodimethanep-quinodimethane

Ph

Ph

Kubo, T. et al. Angew. Chem. Int. Ed. 2005, 44, 6564.

5

Ph =

速度論的安定化

熱力学的安定化thermodynamical stabilization

Kinetic stabilization

Previous WorkR R

1

Tobe, Y. et al. Angew. Chem. Int. Ed. 2013, 52, 6076.

UV-vis-NIR absorption spectra of 1b in CH2Cl2.

m-quinodimethane

1700nm

1a : R = H

1b : R = Mes =

6

Mes Mes Mes Mes

singlet tripletDES-T = -17.6 kJ/mol

Comparision of UV-vis-NIR Spectra

Mes Mes

Mes =Mes =

Mes Mes

1b7

A derivertive of Indeno[2,1-a]fluorene

UV-vis-NIR absorption spectra of 1b in CH2Cl2.UV-vis-NIR absorption spectra of a below compound in CH2Cl2. Tobe, Y. et al. Angew. Chem. Int.

Ed. 2013, 52, 6076.Tobe, Y. et al. Angew. Chem. Int. Ed.

2011, 50, 6906.

Larger p-conjugation space Lower absorption energy

n

acenes

Anthony, J. E. et al. Angew. Chem. Int. Ed. 2008, 47, 452.

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p-Conjugation Space and Absorption Wave Length

New Principle for Low Energy Absorption

1. Moderate singlet biradical character2. Nonalternant hydrocarbon3. Smaller p-conjugation space Lower absorption energy

Nakano.M (unpublished)

1a 2a

HOMO−LUMO Energy Gap : 1a > 2a

Singlet Biradical Character : 1a < 2a

Transition Energy (Prediction) : 1a < 2a9

Nonalternant Hydrocarbons

10Michl, J. et al. Tetrahedron 1976, 32, 205.

HOMO

LUMO

**

* ** ** **

**

azulenenaphthalene

Nonalternant hydrocarbonAlternant hydrocarbon

U Effective Coulombic Repulsion Energy ↘ • Smaller HOMO-LUMO overlap

fE(y) Function of Biradical Factor (y) ↘

• Larger Biradical Factor (y)

Kab Exchange Integral ↗ • Larger Space Separation between HOMO-LUMO• Smaller pi-System

y Biradical Factor ↗ • Increasing U (larger HOMO-LUMO overlap)• Decreasing ɛHL

y=1−1

√1+( 𝑈2𝜀𝐻𝐿

)2𝑓 𝐸 (𝑦 )=1+ 1

√1− (1− 𝑦 )2

𝛥𝐸𝑎𝑏=¿¿Transition Energy :

1

2

3

4

5

6

7

0 0.2 0.4 0.6 0.8 1

f E(y

)

y

𝛥𝐸𝑎𝑏=¿¿

• Moderate biradical character

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Excitation Energy of Biradical Compounds

First Transition Energy :

Kab Exchange Integral ↗ • Nonalternant hydrocarbon• Smaller pi-System

JHHM,

JLLM

Coulombic Integral in HOMO or LUMO ↗

• Smaller pi-System

JHL

Coulombic Integral between HOMO and LUMO

↘• Nonalternant hydrocarbon• Larger Space Separation between HOMO-LUMO

JHHM, JLL

M: Coulombic Integral in HOMO or LUMO

JHL: Coulombic Integral between HOMO and LUMO

K ab=14

( 𝐽 𝐻𝐻𝑀+ 𝐽 𝐿𝐿𝑀−2 𝐽 𝐻𝐿𝑀 )

𝛥𝐸𝑎𝑏=¿¿

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Excitation Energy of Biradical Compounds

Nonalternant Hydrocarbons

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Michl, J. et al. Tetrahedron 1976, 32, 205.

HOMO

LUMO

**

* ** ** **

**

azulenenaphthalene

Nonalternant hydrocarbonAlternant hydrocarbon

First Transition Energy :

Kab Exchange Integral ↗ • Nonalternant hydrocarbon• Smaller pi-System

JHHM,

JLLM

Coulombic Integral in HOMO or LUMO ↗

• Smaller pi-System

JHL

Coulombic Integral between HOMO and LUMO

↘• Nonalternant hydrocarbon• Larger Space Separation between HOMO-LUMO

JHHM, JLL

M: Coulombic Integral in HOMO or LUMO

JHL: Coulombic Integral between HOMO and LUMO

K ab=14

( 𝐽 𝐻𝐻𝑀+ 𝐽 𝐿𝐿𝑀−2 𝐽 𝐻𝐿𝑀 )

𝛥𝐸𝑎𝑏=¿¿Excitation Energy of Biradical Compounds

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New Principle for Low Energy Absorption

1. Moderate singlet biradical character2. Nonalternant hydrocarbon3. Smaller p-conjugation space Lower absorption energy

Nakano.M (unpublished)

1a 2a

HOMO−LUMO Energy Gap : 1a > 2a

Singlet Biradical Character : 1a < 2a

Transition Energy (Prediction) : 1a < 2a15

Mes Mes

Mes =2b

Synthetic Scheme of 2b

OTfTfO

H2SO4

r.t.OHHO

O O

4†

6

Pd2(dba)3CHCl3

CH3CN, 50 °C

KCN

NaOH

ethylene glycol

170 °C

CNNC

587%

79% (2 steps)

OHHO

3

(5 steps) DPPF

O O

7

RLiHO R R R R

THF toluene

OHSnCl2

R =

† 平野慎太朗、大阪大学基礎工学部化学応用科学科、学士学位論文 (2013).

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O O

7

MesMgBrHO Mes Mes Mes Mes

Et2O, r.t. toluene8 2b

OH

37% r.t.

SnCl2

Mes =

conclusion

• Biradicaloids have intermediate nature between the nature of two structure which are a closed-shell and open-shell.

• Indeno[2,1-b]fluorene has a extraordinary optical property.

• Nonalternant hydrocarbons which have moderate singlet biradical character can have the extraordinary optical property.

• Synthesis of fluoreno[2,3-b]fluorene is undergone.

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