Photoactive Molecular Switches Center for Supramolecular Science Department of Chemistry Françisco M. Raymo

Sources Books  Feringa, B. L. (ed.): "Molecular Switches" Wiley-VCH: Weinheim, 2001  Balzani, V.; Venturi, M.; Credi, A.: "Molecular Devices and Machines" Wiley-VCH: Weinheim, 2003 Journals  Irie, M. (ed.): "Photochromism: Memories and Switches" Chem. Rev. 2000, 100, Issue No. 5  Stoddart, J. F. (ed.): “Molecular Machines” Acc. Chem. Res. 2001, 46, Issue No. 6 Reviews  Balzani, V.; Credi, A.; Raymo, F. M.; Stoddart, J. F.: "Artificial Molecular Machines" Angew. Chem. Int. Ed. 2000, 39, 3348–3391  Raymo, F. M.: "Digital Processing and Communication with Molecular Switches" Adv. Mater. 2002, 14, 401–414

Outline Molecular Switches  Definitions  Classification Chemical Control  Operating Principles   Acid/Base Equilibria  Cation Binding  Electron Transfer  Chemo-Optical Logic Gates   Fluorescence Modulation  Transmittance Modulation  Supramolecular Switches   Fluorescence Modulation Optical Control  Operating Principles   cis/trans Isomerizations  Ring Opening and Closing  Electron and Energy Transfer  Chemical and Optical Control   Absorbance Modulation  Fluorescence Modulation  All-Optical Molecular Switches   Absorbance Modulation  Fluorescence Modulation  Refractive Index Modulation Conclusions  Summary  Comparison of Chemo-Optical and All-Optical Molecular Switches

Definitions Input Switching High OutputLow Output What is a molecular switch? It is a molecular or supramolecular system able to modulate an output signal in response to an input stimulation!

More Definitions The input and output of a molecular switch can be:  Chemical signals  Electrical signals  Optical signals A molecular switch can have more than:  One input  One output  Two states Switching OutputInput The states of a molecular switch can be:  Isomers  An acid and its conjugated base  Different redox states of a molecule  The complexed and uncomplexed forms of a receptor

Optical Outputs Switching Optical OutputInput Absorbance Fluorescence Refractive Index Chemical Electrical Optical Photoactive molecular switches have optical outputs! Chemo-Optical Optical OutputChemical Input All-Optical Optical OutputOptical Input

Chemo-Optical Switches Chemo-Optical Optical OutputChemical Input Chemo-Optical Optical Output Chemical Input 2 Chemical Input 1 Chemo-Optical Optical Output Optical Input Chemical Input

All-Optical Switches All-Optical Optical OutputOptical Input Optical Output Optical Input 2 Optical Input 1 All-Optical Optical Output Optical Input 3 Optical Input 2 All-Optical Optical Input 1

One Chemical Input OutputInput FluorescenceH + or M + The chemical input controls the electron transfer process! Energy D* Excitation D* D A Electron Transfer D* Excitation A* A D Electron Transfer

Two Examples OutputInput Fluorescence H+H+ de Silva, A.P.; Gunaratne, H.Q.N.; McCoy, C.P. Nature 1993, 364, 42–44 Fluorescence M+M+

A Molecular NOT Gate High Fluorescence H+H+ Low Fluorescence H + Low High Fluorescence High Low The fluorescence is high only if the concentration of H + is NOT high! I01I01 O10O10 NOT

The fluorescence is high if the concentration of Na + OR K + is high! Na + Low High Fluorescence Low High K + Low High Low High M+M+ Fluorescence A Molecular OR Gate Low Fluorescence OR I10011I10011 O0111O0111 I20101I20101

Two Chemical Inputs Output Input 1Input 2 de Silva, A.P.; Gunaratne, H.Q.N.; McCoy, C.P. Nature 1993, 364, 42–44 H+H+ Na + Fluorescence

The fluorescence is high only if the concentrations of H + AND Na + are high! H + Low High Fluorescence Low High Na + Low High Low High H+H+ Fluorescence Na + A Molecular AND Gate I10011I10011 O0001O0001 I20101I20101 AND Low Fluorescence

Chemo-Optical Logic Gates Akkaya et al. Org. Lett. 2000, 2, 1725–1727 NAND dAMP / dTMP XOR H + / Ca 2+ de Silva et al. J. Am. Chem. Soc. 2000, 122, 3965–3966 de Silva et al. J. Am. Chem. Soc. 1999, 121, 1393–1394 NOR H + / Zn 2+ INH H + / O 2 Gunnlaugsson et al. J. Am. Chem. Soc. 2001, 123, 12866–12876

Design of A XOR Gate Output Input 1Input 2 de Silva, A. P.; McClenaghan, N. D. J. Am. Chem. Soc. 2000, 122, 3965–3966 H+H+ Ca 2+ Transmittance

Operating Principles Low Transmittance High Transmittance Ca 2+ H+H+ High Transmittance Low Transmittance Ca 2+ H+H+ A 390 nm Ca 2+ H+H+ H + + Ca 2+ Absorption Spectra

A Molecular XOR Gate The transmittance is high only if the concentration of either H + or Ca 2+ is high! H + Low High Transmittance Low High Low Ca 2+ Low High Low High H+H+ Ca 2+ Transmittance I10011I10011 O0110O0110 I20101I20101 XOR

A Molecular Half-Adder H+H+ Transmittance Ca 2+ XOR The two molecular switches share the same inputs and can be operated in parallel when dissolved in the same solution! H+H+ Fluorescence AND Ca 2+ H+H+ Transmittance Fluorescence Half-Adder

The fluorescence is high only if the concentrations of H + AND Ca 2+ are high! H + Low High Fluorescence Low High Na + Low High Low High H+H+ Fluorescence Ca 2+ The AND Component I10011I10011 O0001O0001 I20101I20101 AND

A Supramolecular Switch Credi, A.; Balzani, V.; Langford, S. J.; Stoddart, J. F. J. Am. Chem. Soc. 1997, 119, 2679–2681 Input 1 Input 2 Output

The Supramolecular Event  Electron Deficient Component Supramolecular Association Low Fluorescence Electron Rich Receptor High Fluorescence

Mechanism Electron transfer from the host to the guest quenches the fluorescence of the macrocyclic receptor! Low Fluorescence Energy D* Excitation D* D A Electron Transfer

A Chemical Input  Supramolecular Association Low Fluorescence High Fluorescence BuNH 2 The fluorescence is high if the concentration of BuNH 2 is high! Fluorescence Low High BuNH 2 Low High

Another Chemical Input  Supramolecular Association Low Fluorescence H+H+ High Fluorescence The fluorescence is high if the concentration of H + is high! Fluorescence Low High H + Low High

The fluorescence is high only if the concentration of either H + or BuNH 2 is high! H + Low High Fluorescence Low High Low BuNH 2 Low High Low High A Supramolecular XOR Gate I10011I10011 O0110O0110 I20101I20101 XOR Low Fluorescence H+H+ BuNH 2 BuNH 3 +

Optical Inputs Switching Mechanism cis/trans Isomerization Ring Opening/Closing Reaction Electron Transfer Energy Transfer Switching Optical OutputOptical Input Absorbance Fluorescence Refractive Index

cisrans Isomerizations cis/trans Isomerizations Dark 1 Azobenzene Dihydroxychalcone

Dihydrochalcones 365 nm 0.04 (  ) < 1 s 313 nm 0.40 (  ) Dark 22 h (t 1/2 ) Pina, F.; Roque, A.; Melo, M. J.; Maestri, M.; Belladelli, L.; Balzani, V. Chem. Eur. J. 1998, 4, 1184–1191 High Absorbance at 350 nm Low Absorbance at 350 nm The absorbance can be modulated turning on and off an optical input!

Fluorescence Modulation Dark 365 nm 7 (pH) 365 nm Off On Fluorescence Low High H + Low High Low High H+H+ 1 Fluorescence The fluorescence is high only if the optical input is on AND the concentration of H + is high! I10011I10011 O0001O0001 I20101I20101 AND

Ring Opening and Closing Spiropyran Dihydroazulene 1 Dark

Spiropyrans Raymo, F. M.; Giordani, S.; White, A. J. P.; Williams, D. J. J. Org. Chem. 2003, 68, 4158–4169 The absorbance at two different wavelengths can be controlled with a chemical and two optical inputs! 340 nm 560 nm or Dark High Absorbance at 563 nm H+H+ High Absorbance at 401 nm

Input String 000 I1I1 I2I2 I3I3 Input Signals 340 nm 560 nm H+H+ OFF ON O1O1 O2O2 Output Signals Absorbance at 401 nm Absorbance at 563 nm OFF 0 0 ON

Input String 100 I1I1 I2I2 I3I3 Input Signals 340 nm 560 nm H+H+ OFF 0 0 ON 1 O1O1 O2O2 Output Signals Absorbance at 401 nm Absorbance at 563 nm OFF 0 ON nm High Absorbance at 563 nm

Input String 101 I1I1 I2I2 I3I3 Input Signals 340 nm 560 nm H+H+ OFF 0 ON 1 1 O1O1 O2O2 Output Signals Absorbance at 401 nm Absorbance at 563 nm OFF 0 ON nm H+H+ High Absorbance at 401 nm

O1O1O2O2I1I1I2I2I3I3 Truth Table and Logic Circuit Output Signals Absorbance at 401 nm Absorbance at 563 nm Input Signals 340 nm560 nm H+H+

Dihydroazulenes Daub, J.; Fischer, C.; Salbeck, J.; Ulrich, K. Adv. Mater. 1990, 2, 366–369 The nature of the substituents affects dramatically the quantum yield of the photoinduced rearrangement!  (  ) 366 nm 0.40 (  ) Dark 4 h (t 1/2 ) Low Absorbance at 468 nm High Absorbance at 468 nm

411 nm Absorbance Modulation H+H+ Diederich et al. Helv. Chim. Acta 2001, 84, 743–777 The absorbance is high only if the optical input is on AND the concentration of H + is high! 411 nm Off On Absorbance Low High H + Low High Low High Absorbance at 500 nm I10011I10011 O0001O0001 I20101I20101 AND

Two Optical Inputs Diarylethene Furylfulgide 2 1

Diarylethenes 517 nm 0.28  313 nm 0.31 (  ) High Absorbance at 565 nm This diarylethene survives 13,000 switching cycles in aerated hexane! Matsuda, K.; Irie, M. J. Am. Chem. Soc. 2000, 122, 7195–7201

Fatigue Resistance >440 nm 0.01  313 nm 0.68 (  ) High Absorbance at 565 nm The concentration of this diarylethene drops to 80% after 80 switching cycles in aerated hexane and after 200 switching cycles in dearated hexane! Irie, M.; Thorsten, L.; Uchida, K.; Kobatake, S.; Shindo, Y. Chem. Commun. 1999, 747–750

Switching Speeds The concentration of this diarylethene drops to 80% after 70 switching cycles in aerated hexane and after 480 cycles in dearated hexane! Miyasaka, H.; Araki, S.; Tabata, A.; Nobuto, T.; Mataga, N.; Irie, M. Chem. Phys. Lett. 1994, 230, 249– nm 2–3 ps (  ) 355 nm 8 ps (  ) High Absorbance at 560 nm

Refractive Index Modulation Diarylethenes can be trapped in polymer matrices! Tanio, N.; Irie, M. Jpn. J. Appl. Phys. 1994, 33, 3942–3946  n (10 –3 ) Matrix Polyolefin Polymethyl methacrylate Polyfluoroethyl methacrylate (nm) nm 313 nm High Refractive Index Low Refractive Index

A Mach-Zehnder Interferometer Ebisawa, F.; Hoshino, M.; Sukegawa, K. Appl. Phys. Lett. 1994, 65, 2919– nm 313 nm High Refractive Index Low Refractive Index Port 1 Port 2 Port 3 Port 4 Si Wafer SiO 2 TiO 2 Core P3FMA–MMA Cladding SiO 2 TiO 2 Core Doped P3FMA–MMA Cladding Time (s) Power (  W) Port 3 Port On OffOnOff 313 nm 500 nm

Energy Transfer Irie, M.; Fukaminato, T.; Sasaki, T.; Tamai, N.; Kawai, T. Nature 2002, 420, 759– nm 325 nm * * Fluorescence

Electron and Energy Transfer Endtner, J. M.; Effenberger, F.; Hartschuh, A.; Port, H. J. Am. Chem. Soc. 2000, 122, 3037– nm 350 nm 385 nm ** *  High Absorbance at 690 nm R = –(CH) 2 Me

Electronic Motion Lukas, A. S.; Bushard, P. J.; Wasielewski, M. R. J. Am. Chem. Soc. 2001, 123, 2440–2441 Input 2 Input 1 Output 480 nm High Absorbance at 720 nm 420 nm

Mechanism D* D A1* A1 A2 A3 120 ps 420 nm 490 fs 480 nm 5 ps High Absorbance at 720 nm Energy D A1A2 A3

An All-Optical AND Gate 480 nm 420 nm High Absorbance at 720 nm The absorbance is high only if both inputs are applied! 420 nm Off On Absorbance Low High 480 nm Off On Off On I10011I10011 O0001O0001 I20101I20101 AND

Chemical Inputs: A Summary Optical OutputChemical Input Optical Output Chemical Input 1Chemical Input 2 Chemical Input 1 Chemical Input 2 Optical Output

Optical Inputs: A Summary Optical Input 1 Optical Input 2 Chemical Input Optical Input Optical Output Optical Input Optical Output Optical Input 2 Optical Input 1 Optical Input 2 Optical Output Optical Input 1

Chemo- and All-Optical Switches Chemo-Optical Solution Protonation/Deprotonation Complexation/Decomplexation Nuclear Motion Diffusion Limited Byproduct Accumulation Chemical Sensing All-Optical Solution Polymer Matrices cis/trans Isomerization Ring Opening/Closing Electron/Energy Transfer Nuclear Motion Electronic Motion Photodegradation Optical Memories Optical Switches Medium Operating Principles Mechanism Speeds Stability Reversibility Possible Applications     