Andrzej L. Sobolewski Institute of Physics, Polish Academy of Sciences Warsaw, Poland

Kolloquium für Physikalische und Theoretische Chemie, 3.04.2017, Garching

NEW PARADIGMS IN THE PHOTOPHYSICS OF HYDROGEN-BONDED MOLECULAR SYSTEMS

VIS

em

issio

n V

IS a

bso

rptio

n

„Old” photophysical scheme of HB system

PT

VIS

em

issio

n

S0

PT coordinate X-H...Y X…H-Y

UV

abso

rption

S1 PT

(Excited-State Intramolecular Proton Transfer - ESIPT)

Sobolewski & Domcke, Chem. Phys. 184 (1994) 115

CASSCF CASPT2

S0

1nπ

1ππ*

S0

1nπ

1ππ*

PT

Photophysical scheme of o-benzaldehyde

En

erg

y

“keto”

“enol”

S0

S1

UV

ab

so

rptio

n

VIS

em

issio

n

VIS

ab

so

rptio

n

O

O

OH

O

OH

O

PT coordinate

Photophysical scheme of ESIntraPT

Inte

rnal c

onvers

ion

coordinate(?)

CI

PT

PT

<1ps

UV light

VIS light or heat

Photophysics of azobenzene

UV VIS

S0

S1

NH

N

N

NH

Sobolewski & Domcke, J. Phys. Chem. A 111 (2007) 11725

Photophysics of 7-(2’-pyridyl)indole

CI

CC2

Photophysics of 7-(2’-pyridyl)indole

τ= 280 fs in jet

τ =1.0 ps in ACN

Waluk et al., Angew.Chem.Int.Ed., 47 (2008) 603

Kochman & Morrison, J. Chem. Theory Comput., 9 (2013) 1182

θ

PT(50fs)

PT+twist(200fs)

Y H

X

Y

H X

Y H

X X

Y H

PD

PA

S0

S0’

S1 S1’

CI

hn

PT Twist

Photophysics of ESIPT process

Sobolewski, Domcke, Hättig, J. Phys. Chem. A 110 (2006) 6301

Paradigm I:

Twisting around double bond associated

with ESIPT process provides a path for

fast radiationless decay of electronic

excitation in intra-HB molecules

J. Phys. Chem. A 111 (2007) 11725 J. Phys. Chem. A 110 (2006) 6301

Y H

X

Y

H X

Y H

X X

Y H

PD

PA

S0

S0’

S1 S1’

CI

l1

l2

PT Twist

Application of the ESIPT process

Z

S0’

PDA

PA Y

H X Z

Y H

X Z X

Y H

Z

Y

H Z X

Y H

X Z

PT PT Twist

S0

S0’

S1 S1’

CI

l1 l2

Molecular switch based on ESIPT phenomenon

A. L. Sobolewski

Reversible molecular switch driven by excited-state hydrogen transfer

PCCP 10 (2008) 1243

ESIPT

Photophysics of 7-hydroxy-(8-oxazine-2-one)-quinoline

PCCP, 10 (2008) 1243

CI

carbon

nitrogen

oxygen

hydrogen

CC2

Photophysics of a molecular switch

S0

S1 S1

„gre

en

” p

ho

ton

„blu

e”

photo

n

OH NH CO

IR IR

„enol” „keto”

0.0

0.4

0.8

1400 1200 1000 800

0.08

0.04

0.00

-0.01

0.00

0.01 a

bsorb

ance

b

c

wavenumbers /cm-1

a

NO

H

CH3

HO

NO

CH3

OHH

Lapinski et al., ChemPhysChem., 10 (2009) 2290

Photophysics of 7-hydroxy-4-methylquinone-8-carbaldehyde

IR spectrum

before irradiation

IR spectrum

after irradiation

l295nm

IR difference

Spectrum

after irradiation

l360nm

l ≤ 295 nm

l ≤ 360 nm

Paradigm II:

Molecular photoswitches or transistors

based on the ESIntraPT phenomenon:

- photostable

- chemically tunable

- fast

hn1 hn1

hn1

hn1

J. Phys. Chem. C, 113 (2009) 10315 J. Mol. Model. 20 (2014) 2163

PCCP, 10 (2008) 1243

X,Y=N,O

X-H...Y

Intra-molecular hydrogen bonds

Inter-molecular hydrogen bonds

X,Y=N,O

X-H...Y

Photophysics of an acidic chromophore

X,Y=N,O

X-H

abs

carbon

nitrogen

oxygen

hydrogen

A”

A’

Sobolewski, et al., 1999-2005

p

p*

s*

πσ* paradigm of photoacids

NH

H diss abs

50fs

IC (exp100fs)

Photofragment velocity map imaging of H atom elimination in the first excited state of pyrrole F. Temps et al., PCCP, 5 (2003) 315

Photophysics of pyrrole

σ* 1sH

Chem. Phys. Lett. 321 (2000) 479

TKER spectroscopy

M.N.R. Ashfold et al., PCCP, 12 (2010) 1218

hν

εk

A. L. Sobolewski and W. Domcke

Photoinduced electron and proton transfer in phenol and its clusters with water and ammonia

J. Phys. Chem. A 105 (2001) 9275

Photophysics of phenol and phenol-H2O complex

3sH2O σ*

1sH

σ*

3sH2O

Hydrated hydronium clusters: SOMO orbital

e¯

H3O+

H3O (H3O)W1

(H3O)W3 (H3O)W6

(H3O)W9

A. L. Sobolewski and W. Domcke

Hydrated hydronium: a cluster model of the solvated electron?

Phys. Chem. Chem. Phys. 4 (2002) 4

Hydrated electrons(?)

Abel, Buck, Sobolewski, Domcke,

On the nature and signatures of the solvated electron in water,

PCCP, 14 (2012) 22

Paradigm III:

Hydrogen (or any of the first column metal) atom injected

into a saturated polar solvent ionizes spontaneously into

proton (cation) and a solvated electron

e¯

H3O+

(H3O)W9

e–

K+

K(H2O)20

Inter-molecular hydrogen bonds

X,Y=N,O

X-H...Y

„non-saturated” chromophores?

guanine

X-H...Y

cytosine

Photophysics of the GC base pair

Sobolewski&Domcke, PCCP 6 (2004) 2763

LE(G) LE(C)

CT(GC)

p(G) p(C)

p*(G) p*(C)

Photophysics of guanine-cytosine base pair

[fs]

IC

CI

CI

abs

CC2

Hobza, De Vries, et al., PNAS, 102 (2005) 20

WC type

non-WC type

Photophysics of guanine-cytosine base pairs

REMPI spectra

Photophysics of guanine-cytosine base pairs

Sobolewski, Domcke, Hättig, PNAS., 102 (2005) 17903

CT

CT CT >ps

fs >ps

CC2

S0

1LE

1CT

PT coordinate

En

erg

y

coupling coordinate

IC

ET [X–...(H-Y)+]hot

X-H...Y

ab

so

rpti

on

(X-H...Y)*

[(X-H)...Y–]hot

Sobolewski & Domcke

ChemPhysChem, 7 (2006) 561

Electron-Driven Proton-Transfer (EDPT) proces

IC

X•...(H-Y)•

e-

e-

ET

e-

Photochemistry of the GC base pair in vacuum.

.

CASSCF NBO dynamics simulations

Michael A. Robb et al., J. Am. Chem. Soc. 2007, 129, 6812-6819

Hydrogen-bonded bio-structures

DNA proteins

cellulose

Paradigm IV:

EDPT process provides an universal mechanism for ultra-fast radiationless decay of electronic

excitation in nucleotides, peptides, and in strands of DNA and RNA.

Hydrogen bonds are a key not only for functionality of biological matter,

but also for its photostability.

AMP Gly-Phe-Ala G-C/A-T J. Phys. Chem. A, 118 (2014) 122 JACS, 131 (2009) 1374 PNAS, 102 (2005) 17903

J. Phys. Chem. A 110 (2006) 9031

S0

1L

E

1CT

PT coordinate

Energ

y

Coupling coordinate

IC

ET [X–...(H-Y)+]hot

X-H...Y

ab

so

rpti

on

(X-H...Y)*

[(X-H)...Y–]hot

Sobolewski & Domcke

ChemPhysChem, 7 (2006) 561

photoreactivity

photostability

IC

X•...(H-Y)•

X-H...Y

Y...H-X

X-H...H

X-H...Y

e-

e-

ET

e-

Electron-Driven Proton-Transfer (EDPT) proces

Photophysics of a single-HB system

X-H...Y X...H-Y hn

X + H-Y

oxidation reduction

if X-H HO-H

photo-oxidation of water!

photo-redox reaction

HO + H-Y

hn(?)

X. Liu, A.L. Sobolewski, R. Borrelli, W. Domcke, PCCP 15 (2013) 5957

Photophysics of pyridine-H2O complex

π*

π

n

2pz(O)

2px(O)

π*

1,3pxπ*

1,3pzπ*

CC2

OH• PyH•

abs

Photophysics of pyridine-H radical

CC2

abs

hν(UV)

electron/proton

transfer

hν(UV) H-detachment

+H2O

∆

hydrogen-bond

breaking

water

splitting

Pyridine-H2O: The photocatalytic cycle

X. Liu, et al.., PCCP 15 (2013) 5957 J. Phys. Chem. A, 118 (2014) 7788

C. Jouvet, et al.., PCCP 18 (2016) 25637 Photoinduced water splitting in pyridine water cluster

theory experiment

N

N

N NH2NH

2

Heterocycles absorption vs. the solar spectrum

Ac

BA

AO

Xiaojun Liu, Tolga N.V. Karsili, Andrzej L. Sobolewski, Wolfgang Domcke

Photocatalytic water splitting with acridine dyes: Guidelines from computational chemistry

Chemical Physics, Volume 464, 2016, 78–85

+H2O

hν(Vis) electron

driven

proton

transfer

-OH

hν(Vis) H-detachement

Theory: Sobolewski&Domcke, PCCP 14 (2012) 12807

Experiment: Morawski et al., PCCP 16 (2014) 15256

Oxotitanium porphyrin-H2O: The photocatalytic cycle

Paradigm V:

Photoreactivity (redox reaction) related to EDPT process provides a template for designing

molecular systems which can catalyse photochemical splitting of water.

pyridine TiO-porphyrin TiO-phthalocyanin

PCCP 14 (2012) 12807 PCCP 16 (2014) 15256

J. Phys. Chem. C, 119 (2015) 14085 PCCP 15 (2013) 5957 J. Phys. Chem. A, 118 (2014) 7788

Photophysics of Hydrogen-Bonded Systems A summary

X-H...Y

X,Y=N,O X-H...Y

Intra-molecular HB Inter-molecular HB

e e

PT vs. HT dilemma

1CT 1LE

S0

PT coordinate

absorp

tion

PT coordinate

En

erg

y

S0

S1 “keto”

“enol”

absorp

tion e

mis

sio

n

carbon

nitrogen

oxygen

hydrogen

PT

HT

HT

PT

HT

Acknowledgements

Theory: Dr. Joanna Jankowska Dr. Michal F. Rode Experiment: Prof. Maciej Nowak Dr. Olaf Morawski Dr. Elena Karpiuk Dr. Leszek Lapinski

Theory: Prof. Wolfgang Domcke Dr. Xiaojun Liu Dr. Deniz Tuna Dr. Tolga N. V. Karsili Dr. Dorit Shemesh

Thank you for your attention!

A”

A’ abs

H-diss IC

e–

H3O+

Solvated electron

abs IC

PT

Photostability

Molecular switch Photocatalytic water splitting

TKER spectroscopy

New paradigms in photophysics of hydrogen-bonded molecular systems

A general overview

Photosynthesis

Photosystem II

Chlorophyll absorption spectrum

Qy

Qx

Soret

UV OH-/H+

adsorbed H2O H2O@TiO2

TiO

Photophysics of TiOP: theory

1,3CT

S0

1Q

1B

LE(Q,B) CT

Ti

Ti(IV)

Ti(III)

O

S0 + H2O

hυ

CT

O ●

+ + _

+ OH ● OH ●

(?)

Sobolewski&Domcke, PCCP 14 (2012) 12807

Photophysics of TiOP:H2O complex

OH

photogeneration

of OH radicals

from water

Theoretical

prediction:

Spectroscopic detection of OH

radicals

340 360 380 400 420 440 460 480 500 520 540 560 580 600

0

500

1000

1500

2000

2500

3000

3500

4000

4500

without illumination

illumination 0.5 h

illumination 1.5 h

illumination 2.5 h

illumination 3.5 h

illumination 4.5 h

illumination 5.5 h

Flu

ore

scen

ce i

nte

nsi

ty, a.

u.

Wavelength, nm

λexc=315nm

HTA fluorescence vs. TiOP illumination

Morawski et al., PCCP 16 (2014) 15256

IC

abs

TiPOH TD/DFT/cc-pVDZ(TZVP) MEP Photophysics of TiPOH radical

ns-s

EVR

Exte

rnal vib

rational bath

S0

S1

IVR

ps

Inte

rnal vib

rational bath

Photostability via EDPT process

UV VIS

EDPT

fs

NH

/OH

str

etc

h

IR

CC2

Photophysics of indole-ammonia complex

Sobolewski & Domcke, Computational studies of the photophysics of hydrogen-bonded molecular systems, J. Phys. Chem. A, 111 (2007) 11725, feature article

3sNH4

3sNH3

Photophysics of pyridine-ammonia complex

CC2

ET

J. Phys. Chem. A, 111 (2007) 11725

ET