5/23/2015 international symposium on molecular spectroscopy : 65th meeting 1 doubly hydrogen bonded...

04/18/23 International Symposium on Molecular Spectroscopy : 65th Meeting

1

DOUBLY HYDROGEN BONDED BIS-(4-HYDROXYPHENYL)METHANE DIMERS. DOUBLY HYDROGEN BONDED BIS-(4-

HYDROXYPHENYL)METHANE DIMERS.

Chirantha P. Rodrigo, Evan G. Buchanan, William H. James III and

Timothy S. Zwier.Department of Chemistry, Purdue University, West Lafayette, IN

47907

HO OH2


2

BIS-(4-HYDROXYPHENYL)METHANE Monomers

• b4hpm structure. Two para-cresol moieties connected through a methelyne group. Four torsional degrees of freedom along PhOH, PhCH2 coordinates. Giving rise to three

possible conformational minima (and their enantiomers). Two symmetric (C2) and one asymmetric (C1) structures.

C2C1

RelativeEnergies:B3LYP/6-31+G(d)

0 cm–1 13 cm–1 7 cm–1dd (down-down) uu (up-up) ud (or du)

Gaussian 09 program suite.

H

H

OO

H H

H

H

OO

H

H


3

• b4hpm spectroscopy. Two conformations observed in supersonic jet expansion. Both showed C2 symmetry in

ground and the first excited state . Symmetric dd and uu structures observed in the gas phase. Nearly identical UV and IR (torsional modes, CH stretch and OH stretch) spectra

observed.

The states energy splitting is 132 cm–1 for both conformers.

BIS-(4-HYDROXYPHENYL)METHANE Monomers

10A(S )X

1 11 2B(S ) A(S )A B

11B (S )A

inte

nsit

y / (

arb.

uni

ts)

3550035450354003535035300352503520035150

Energy / cm–1

+132 cm–1

S2 Origin

+132 cm–1

S2 Origin

monomer conformer A

monomer conformer B

35 184 cm–1para Cresol S135 337 cm–1

S1 Origin

S1 Origin

3100300029002800

Frequency / cm–1

inte

nsit

y (a

rb. u

nits

)

368036603640

Frequency / (cm–1)

3656


4

• b4hpm spectroscopy. Two nearly isoenergetic conformations. Nearly identical spectra in UV and IR. Both conformations possess C2 point-group symmetry in both ground and first excited

states. Two close lying excited states (S1 and S2) which are separated by 132 cm–1.

BIS-(4-HYDROXYPHENYL)METHANE MonomersSummary of Results and Conclusions

dd (down-down) uu (up-up)

132 cm 1 *AB*A B

AB

1 * *A B AB

2 * *A B AB


5

Supersonic Jet Expansion & Spectroscopic Methods: UV(R2PI, FES, SVLF) / UVHB / UVD / S0-RIDIRS

Collisional cooling to zero-point vibrational

levels

Probe laser

Probe20 HzUV

Probe20 HzUV

M+ + e

FES / SVLF R2PI UV-Depletion

Δt=200 ns

Pump10 HzUV

Probe20 HzUV

M+ + e

Δt=200 ns

Pump10 HzUV

Probe20 HzUV

M+ + e

UV-Holeburning

Δt=200 ns

Pump10 HzIR

Probe20 HzUV

M+ + e

S0- RIDIRS

b4HPM Dimer

Inte

nsity

/ (a

rb. u

nits

)

3535035300352503520035150351003505035000349503490034850Energy / (cm

–1)

b4HPM+(H2O)1Origin

(b4HPM)2Origin

MonomerOrigin

Fluorescence Excitation Spectrum in Monomer, Dimer and (H2O)1 cluster region.In

tens

ity

/ (ar

b. u

nits

)

352003515035100350503500034950349003485034800Energy / cm

–1

*

*R2PI

UVHB Conformer B

UVHB Conformer A

monomerorigin

13 cm–1


7

para-Cresol and Phenol Dimers

• Phenol Dimer Fuke, K.; Kaya, K. Chem. Phys. Letters 1982, 91, 311. Fuke, K.; Kaya, K. Chem. Phys. Letters 1983, 94, 97. Weichert, A.; Riehn, C.; Brutschy, B. J. Phys. Chem. A 2001, 105,

5679. Schmitt, M.; Böhm, M.; Ratzer, C.; Krügler, D.; Kleinermanns,

K.; Kalkman, I.; Berden, G.; Meerts, W. L. Chem. Phys. Chem. 2006, 7, 1241.

• para-Cresol Dimer Appel, I.; Kleinermanns, K. Ber. Bunsenges. Phys. Chem. 1987,

91, 140. Yan, S.; Spangler, L. H. J. Phys. Chem. 1991, 95, 3915.

O

H

O

H

A

A

D

D

CH3

H3C

O

H

O

H


8

Formation of b4HPM Dimers

• Possible Dimer Formations. O—H······O—H type Hydrogen bonded dimers

π ······H—O type Hydrogen bonded dimers

O

H

O

H

O OHH

O

H

O

H

O OH

H

OH

O

HO O

H

H

Proton Donor : D

Proton Acceptor : A

A A

D D

D A

A D

Electronic States

~132 cm 1

S3

S4

~655 cm 1

Donor

Acceptor

~132 cm 1

S1

S2

O

H

O

H

O OHH

O

H

O

H

O OH

H

A A

D D

D A

A D

O

H

O

H

O

H

OH

132 cm 1

S1

S2

655 cm 1

S1

S2smallsplitS3

S4

~655 cm 1

Donor

Acceptor

smallsplitS1

S2

Fuke, K.; Kaya, K. Chem. Phys. Letters 1983, 94, 97.

b4HPM monomer spectroscopy

A

D


10

Conformational Search and Low Energy Structures

• MacroModel Conformational SearchEnergy levels calculated with MM (Amber*)

• Becke3LYP/6-31+G(d) Geometry Optimization (with zero-point correction)

S1S2

S20

……

……

……

..

Singly H-bonded +

π····H—O bonded stuctures,

Doubly π····H—O bonded.

Doubly hydrogen-bonded dimers.

Rela

tive

Ener

gy (k

J/m

ol)

S9S7

S14

S17S13

S11

S15

S19

S12

S4

S6S10

-2

3

8

13

18

23

S21

……

……

……

……

…

S2

S3Singly H-bonded,π stacked

Doubly bonded dimers.

Gaussian 09 program suite.

D

D

A

A

D

D

A

A

A

A

D

D

D

D

A

A

D

A

D

A


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Low Energy Structures

• Becke3LYP/6-31+G(d) Geometry Optimization (with zero-point energy correction)

• The lowest energy dimer is formed out of two ud/du monomers.• uu appears only in one dimer (S19)

S9 (0 cm–1): C2 (ud+du) S7 (135 cm–1) : C1 (dd+ud) S13 (160 cm–1) : C2 (dd+dd)

S19 (255 cm–1) : C2 (dd+uu)S11 (189 cm–1) : Ci (ud+du)S17 (173 cm–1) : C1 (dd+ud)

NOTENOTE

A

A

D

D


12

UV Depletion Spectroscopy

Inte

nsit

y / (

arb.

uni

ts)

352003515035100350503500034950349003485034800Energy / cm

–1

UVHB Conformer B

UVHB Conformer Amonomerorigin

Inte

nsit

y / (

arb.

uni

ts)

357003560035500354003530035200351003500034900

Energy / cm–1

monomer S1-S0 origin

393 816450

156 644

116

116

B

A

C

6a1 12

1


13

Conformer AConformer A: UVD

Inte

nsit

y / (

arb.

uni

ts)

400350300250200150100500-50

Relative Energy from ZPL / cm–1

116 231

monomerorigin

Appel, I.; Kleinermanns, K. Ber. Bunsenges. Phys. Chem. 1987, 91, 140.

para-cresol LIF

para-cresol dimer:

108 cm-1 band assigned as intermolecular stretch fundamental.

+116 cm–1 : S2 Origin or low frequency vibrational fundamental?

S2?


14

Conformer A

Conformer A: UVD and SVLF

6050403020100

Inte

nsit

y / (

arb.

uni

ts)

4003002001000

Energy from zero point level / (cm-1

)

1219

2124

28

31

34 44 103 133

Origin SVLFConformer A

UVDConformer A

116

18

24

32

4048 +16

+24

+40

+33


15

Conformer B

Conformer B: UVD and SVLF

Inte

nsit

y / (

arb.

uni

ts)

4003002001000

Energy from zero point level / (cm-1

)

Origin SVLFConformer B

9

17

23

33

4048

5665

72 102

UVDConformer B

9

1924

34

4351

58

156108


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S0-RIDIRS: C—H Stretch

3100305030002950290028502800

Frequency / cm–1

B

S9(C2)

S11(Ci)

S13(C2)

3100305030002950290028502800

Frequency / cm–1

A

S7(C1)

S17(C1)

S19(C2)


17

S0-RIDIRS: O—H Stretch

370036503600355035003450

Frequency / cm–1

S7 (C1)

S17 (C1)

A

B

3649

3642

3510

+9

+13

370036503600355035003450

Frequency / cm–1

S9(C2)

S11(Ci)

S13(C2)

S19(C2)

A

B


18

Conclusions & Future WorkIn

tens

ity

/ (ar

b. u

nits

)

357003560035500354003530035200351003500034900

Energy / cm–1

393 816450

156 644

116

B

A

• Origins of other excited states (S2, S3 etc.) ?• Ground state conformational assignments.• Higher level theoretical calculations.

1. Functionals that better account for dispersion (M05-2X, ωB97xD etc.)2. Excited state energies, geometries and frequencies.


19

Acknowledgment

AdvisorAdvisor: : Prof. Timothy S. ZwierZwier Research GroupZwier Research Group• Dr. William H. James III (Post Doctoral fellow)• Dr. Anna Gurtbelet (Post Doctoral fellow)• Josh Sebree• Evan Buchanan• Zachary Davis• James Redwine• Deepali Mehta• Jacob Dean• Nathan Kidwell

Computational Resources:Computational Resources:

• Purdue ITap

Funding:Funding:• Department of Energy

Past Group membersPast Group members Dr. Christian W. Müller Dr. Josh J. Newby Dr. Nathan R. Pillsbury Dr. Esteban E. Baquero Dr. Virgil A. Shubert Dr. Tracy A. LeGreve Dr. Jasper R. Clarkson Dr. Talitha Selby Dr. Ching-Ping Liu

Collaborator : Collaborator : Dr. David F. PlusquellicDr. David F. PlusquellicCollaborator :Collaborator : Prof. Lyudmila Slipchencko Prof. Lyudmila Slipchencko

5/23/2015 international symposium on molecular spectroscopy : 65th meeting 1 doubly hydrogen bonded...

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