Photochromism - Fundamentals and Applications -

Masahiro Irie Department of Chemistry and Biochemistry Kyushu University, Fukuoka, Japan Energy Photosynthesis

Photon

Information Photoresponsiveness

Vision Phototaxis Phototropism Photochromism

hν Natural A B hν’ Photoreceptor : Rhodopsin (Chlamydomonas) Bacteriorhodopsin

0.4 I Y 366 nm Y Phytochrome

I 514 nm 0.3 X X Mineral : Sodalite bance r

0.2 I Abso

0.1 I Artificial

II II II 300 350 400 450 500 550 600 λ / nm Dyes : Spirobenzopyran, Azobenzene・・・ Matel-oxide Glass Chalcogenide Glass N N N N

NO2 H3CCH3 H3CCH3

N ONO2 - N+ O R R O O CH3 CH3

H C CH O H CCHO 3 3 3 3 O O H C H3C 3 CH3 O CH3 O

F2 F2 F2 F2 F2 F2

CH3 CH3 S S S S CH3 CH3 Brief History of Photochromism

1867 M. Fritsche O O hν, O2

∆

1899 W. Marckwald

O O Cl hν Cl + Cl Cl ∆ Cl Cl Cl Cl

(G. Scheibe et al. J. Phys. Chem. 66, 2449 (1962)) 1952 E. Fischer, Y. Hirsberg

Me Me Me Me hν

N O ∆ N O Me Me (J. Chem. Soc., 4522 (1952))

Self-developing, Dry Photographic Systems

High-speed Printing Materials Chemical Computer Camouflage Fabrics

NCR(Spiropyran) R C A (Indigos) American Cyanamid (Spiropyrans, Metal Dithizonates) EG & G (Triarylmethane Leuco Derivatives) Fuji Film (Spiropyrans) 1970 ~ 1980 Dark Ages

Lack of fatigue resistant characteristics (photo-degradation) "Photochromism" G. Brown Ed.

1980 ~ Present Renaissance

Fatigue Resistant Spironaphthoxazine

Me Me Me Me N hν N

N O ∆ N O Me Me

Thermally Irreversible Compounds

Me O Me O hν O Me Me Me Me O O O Me hν' O Me Me O Me Name Reaction

Azobenzene hν NN N N hν', ∆ Spirobenzopyran NO2 H3C CH3 H3C CH hν 3 + - N ONO2 N O R hν', ∆ R Naphthopyran

hν

O hν', ∆ O Thioindigo O S hν SS

S O hν', ∆ OO

Anthracene Dimer hν

hν', ∆

Dihydroazulene NC NO2 CN hν CN hν', ∆ NO2 CN Name Reaction

F Diarylethene F2 2 F2 F2 F2 F2 hν CH3 CH 3 SS hν' H3C SSH3C

Furyl Fulgide CH3 O CH3 O hν CH3 O CH O H3C H3C 3 O O H C hν' 3 O H C O CH3 3 CH3 Naphthacene quinone O O

hν O O O O hν'

R R Stilbene Derivative

hν O CH3 H3C O CH3 CH3 hν' S S Requirements for Photonics Devices

hν A B hν’

1. Thermal stability of both isomers 2. Fatigue resistant character: repeatable cycle number > 104 3. High sensitivity: quantum yield > 0.5 4. Rapid response

5. Reactivity in the solid state A New Class of Photochromic Compounds Thermally Irreversible and Fatigue Resistant Diarylethenes

H H H H 2 R R5 R2 R5 1 H R R1 H R3 4 6 3 R6 X R Y R R X R4 Y

CH2CN F2 O N F2 F2 : OOOO , ,

2 2 R R Me : 3 1 1 3 Me S Me , Me , R X R , R Y R S N Me Me MeO Me

Me S OEt , N , NC S Me Me 780 nm 488 nm ： 6 R ： 5 R Y 4 1 R R sec X -11 2 R backward reaction < 10 forward reaction 3 R Rapid response Reactivity in the crystalline phase Sensitivity at visible region

・ ・ ・ ' ν ν h h 5 10 C C ： ° 6 ° R 5 R 0.1 - 4 1 R ： R XY 2 R 3 R 470,000 years at 30 long term stability : long term 1.0 short term stability : 150 repeatable cycle number quantum yield Both isomers are thermally stable Low fatigue High sensitivity

・ ・ ・ Molecular Design of Diarylethenes

Thermal Stability Fatigue Resistant Character Response Time Molecular Orbital Calculation

• Thermal reaction - - - disrotatory mode

BC

A BC D A D

• Photochemical reaction - - - conrotatory mode

A C

A BC D B D Conrotatory Mode - - - Photochemical Reaction Process

A ( 48,48 ) A ( 50,46 )

A ( 50,46 ) A ( 12,42 ) B ( 49,47 ) A ( 42,42 ) A ( 48,48 ) B ( 43,41 ) B ( 49,47 ) A ( 42,42 ) B ( 43,41 ) A ( 50,46 )

A ( 44,40 ) A ( 48,48 )

A ( 12,42 ) O O

OO Molecular Design Principle Thermal Irreversibility

“ When the compound has aryl groups with low aromatic stabilization energy, both isomers of the diarylethene are thermally stable.”

> > >> SS O O NN

Stable Unstable φ 1 - φs P s A B φB→A

φs = 0.001 (φB→A = 1) After 103 cycles

[A] ～ 0.37 [A]0

φs = 0.0001 (φB→A = 1) After 104 cycles

[A] ～ 0.37 [A]0 Molecular Design Principle Fatigue Resistant Character

F2 F 2 F2 F2 F2 F2 H3C CH3

Crystalline CH3 CH3 Systems S H3C S S H3C S > 100,000 > 10,000 ~ 2,000

F2 F F2 F2 2 F2 F2

CH3 CH3 S H3C S CH H3C S H3C S 3 ~ 200 ~ 80 UV

Vis.

Dichroism

F2 F2 F2 F2 F2 F2

CH3 CH3 S CH S CH H3C CH3 H3C 3 3 S CH3 S J. Am. Chem. Soc. 121, 2380 (1999) F F2 2 F2 F F2 F2 2

CH CH3 O N 3 NO 2 2 NO O2N S CH3S 2 S CH3 S J. Am. Chem. Soc. 121, 8450 (1999) Nano-layered Structure

F2 F2 F2 F2 F2 F2

F Me F UV F Me F F F F F S Me S S Me S F FFF Vis. F FFF F F F F 1a 1b

F2 F2 F2 F2 F2 F2 UV Et Et S S S S Et Vis. Et 2a 2b

Photochem. Photobio. Sci. ２,1088 (2003) Chem. Rec. 4, 23 (2004) X-ray Crystallographic Analysis

F2 F2 F2 F2 F2 F2

CH3 CH3 CH H3C 3 H3C S S CH3 S S CH3 CH3 1a 1b

J. Am. Chem. Soc. 122, 1589 (2000) Bull. Chem. Soc. Jpn. 73, 2179 (2000) 1.0 F2 F2 F2 Me or H H or Me 0.8 R F 2 S R S F F 2 2 R' R' R1 R1 0.6 Me 2 R2 S R Φ S Me 0.4

F2 F2 F2 0.2 Me R R S Me S 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 Distance between the reacting carbon atoms / A

J. Phys. Chem. A. 106, 209 (2002) Chem. Commun. 2804 (2002) Surface Morphology Changes of Single Crystal 1

F2 F2 F2 F2 F2 F2

CH H CCH H3C 3 3 3 CH3 CH3 S S S S H3C H3C

Science, 291, 1769 (2001) UV

Vis.

(100) Absolute Asymmetric Photosynthesis

2 5 hν 2 5 R R R2 R5 R R 1 4 R1 R + R 3 6 R3 4 R6 3 6 R R X R X hν', ∆ R X X R X 1 X R4 R (R,R) (S,S)

Ang. Chem. 42, 1636 (2003) Tetrahedron Lett. 42, 7291 (2001) J. Am. Chem. Soc. 122, 9631 (2000)