趙奕姼 Ito Chao

Charge-Controlled Hydrogen Bonds

in Conjugated Molecules

Covalent bond synthesis

Covalent bond + Non-covalent bond synthesis

Rosette Nanotubes as Conduits

H. Fenniri et al, J. Am. Chem. Soc. 2002, 124, 11064

Time

Hydrogen bonding changes properties of bound molecules – e.g. sensors

N N

N N

Ru2+

2

N

O

H

O

N HN

N N

N

H HO O

P

O O

PhPh

• UV-visible absorption and luminescence spectra changed upon H-bonding

Watanabe, S. et al. J. Am. Chem. Soc. 1998, 120, 229.

How about control hydrogen bonding viaa remote center?

Polarized amide groups enhance binding strength in hydrogen-bonded metallocene complexes

O

HN

R

HN

O

R' 'R

Co+Co+PF6

- PF6-

R' = CO2Et, H

A-

O

HN

R

HN

O

R' 'R

Co+Co+PF6

- PF6-

R' = CO2Et, H

A-

Beer, P. D.

OH OH

OO

Glutaric Acid

M

CHN

N

CHN

N

O

O

KFe2+ = 4600 M-1

K Fe3+ = 158000 M-1

KCo2+ = 2800 M-1

KCo3+ = 98000 M-1

Tucker, J. H. R. et al. Angew. Chem. Int. Ed. 2000, 39, 3296.

More acidic amide proton based on X-ray and IR results

*

* *

*

*

*

*

*

Implication of charge control in supramolecular chemistry

BridgeReactionCenter

BindingCenter

Re

action(protonation

)P

rope

rty

chan

ge

(H-b

ond

ener

gy)

Signal transduction

NX

X NH n

H+

HH3N

N

X X

N

H

H

H

A N

X X

N

H

H

H

B

rts

u

v

Charge delocalization of the protonated system

N

C C

H

C CN

H

4-i

n C=C(N) C=C(P) N=N(N) N=N(P)

1 -6.84 -13.17 -7.39 -15.50 2 -6.73 -12.04 -7.66 -16.45 3 -6.64 -11.18 -7.84 -17.99 4 -6.57 -10.47 -7.95 -19.07

N

X X

N

nH

H

Table 1. Ammonia binding energies (kcal/mol) with three-component and two-component systems (4i) calculated at the HF/6-31G* level

Chao, I.; Hwang, T.-S. Angew. Chem. Int. Ed. 2001, 40, 2703.

H+

H3N

4-i -6.22 -7.27 Signal does not die out!

Bond length variation in pyrrole-(X=X)n-imine systems

N

X X

N

H

H

H

A N

X X

N

H

H

H

B

rts

u

v

(C=C)n

1.2

1.3

1.4

1.5

r s t u v

r

(N=N)n

1.2

1.3

1.4

1.5

r s t u v

r

n=1

n=2

n=3

n=4

N P

N

C C

H

C CN

H

4-i

n C=C(N) C=C(P) N=N(N) N=N(P)

1 -6.84 -13.17 -7.39 -15.50 2 -6.73 -12.04 -7.66 -16.45 3 -6.64 -11.18 -7.84 -17.99 4 -6.57 -10.47 -7.95 -19.07

N

X X

N

nH

H

Table 1. Ammonia binding energies (kcal/mol) with three-component and two-component systems (4i) calculated at the HF/6-31G* level

Q(pyr)a Q(pyr)a

(0.27) (0.42)(0.22) (0.47)(0.18) (0.59)(0.15) (0.66)

a Difference in Mulliken group charge of pyrrole between protonated and neutral three-component systems.

Chao, I.; Hwang, T.-S. Angew. Chem. Int. Ed. 2001, 40, 2703.

H+

H3N

4-i -6.22 -7.27 Signal does not die out!

Table 2. Ammonia binding energy (kcal/mol) of protonated three-component systems with (N=N)n bridges calculated with ab initio and DFT methods.

n = 1 n=2 n=3 n=4

HF/6-31G* -15.50 -16.45 -17.99 -19.07

HF/6-31+G** -13.41 -14.29 -15.77 -16.78

HF/6-31+G(2d,2p) -12.94 -13.90 -15.36 -16.33

B3LYP/6-31G* -19.19 -19.37 -19.57 -19.79

B3LYP/6-31+G** -16.06 -16.26

PW91PW91/6-31G* -21.77 -21.88

PW91P86/6-31G* -22.76 -22.87

MP2/6-31G* -18.72 -19.27 -20.08 -21.43

MP2/6-31G*// -18.73 -19.30 -20.07 -21.10

B3LYP/6-31G*

MP4(SDQ)/6-31G* -17.75 -19.04

MP4(SDQ)/6-31G*//

B3LYP/6-31G* -17.42 -18.30

CCSD(T)/6-31G*//

MP4(SDQ)/6-31G* -20.30a -21.04a

a Not corrected for BSSE.

Table 3. Ammonia binding energy (kcal/mol) of the protonated three-component system with different -((CH=CH)n-N=N)x- bridges at the HF/6-31G* level.

x = 1 x = 2

-(CH=CH-N=N)x- -14.63 -15.62

-((CH=CH)2-N=N)x- -13.90 -14.49

-((CH=CH)3-N=N)x- -13.19 -13.64

-((CH=CH)4-N=N)x- -12.61 -12.98

Signal maintenance still possible with more feasible bridges

Binding Site Linker Reaction Center

NH3…Pyrrole

X=X X=X-N=N N=N-X=X X=X-C=C C=C-X=X

C=NH

C=NH2+

C=C C=C-N=N N=N-C=C

N=N N=N-C=C C=C-N=N

C=N C=N-N=N N=N-C=N C=N-C=C C=C-C=N

N=C N=C-N=N N=N-N=C N=C-C=C C=C-N=C

C≡C

N

X X

N

nH

H N

X X

N

nH

H

H

H+

Neutral (N) Protonated (P)

Ammonia binding energy of protonated pyrrole-(X=X)n-imine

(C=C)n

(N=N)n

(C=N)n

(N=C)n

-20

-18

-16

-14

-12

-10

-8

1 2 3 4

n

Bin

din

g E

ner

gy (

kca

l/mol

)

(C≡C)n

(C=C-N=N)n

(C=C-C=N)n

(C=C-N=C)n

(N=N-C=C)n

(C=N-C=C)n

(N=C-C=C)n

(N=N-C=N)n

(N=N-N=C)n

(C=N-N=N)n

(N=C-N=N) n

-20

-18

-16

-14

-12

-10

-8

1 2

n

Bin

din

g E

ner

gy (

kca

l/mol

)Ammonia binding energy of protonated

pyrrole-(X=X-X=X)n-imine

Model construction

HOMO

LUMO

pyrrole bridge-iminium (two-component system)

NH CH=NH2+

qLUMO

partialcharge transfer

QHQH (whole mol.)

E

0.40 0.41 0.42 0.43 0.44 0.45 0.46 0.47 0.48-22

-20

-18

-16

-14

-12

-10

-8

-6

Figure. Correlation of binding energies and charges of hydrogen atoms of pyrrole N-H bond.

y = -176.5445x + 63.3432

R2 = 0.9687

Bin

din

g E

ne

rgy

/ k

ca

lmo

l-1

QH / a.u.

Correlation of binding energy and QH

QH

NX

X NH n

H+

HH3N

0 1 2 3 4 5

0.41

0.42

0.43

0.44

0.45

0.46

0.47

R2 = 0.9821

R2 = 0.9734

R2 = 0.8832

R2 = 0.3714

R2 = 0.0258

qLUMO

= 0.000 ~ 0.049

qLUMO

= 0.050 ~ 0.149

qLUMO

= 0.150 ~ 0.249

qLUMO

= 0.250 ~ 0.349

qLUMO

= 0.350 ~ 0.510

Ch

arg

e at

H A

tom

of

Py

rro

le N

-H B

on

d (

a.u

.)

E (eV)

QH

(a.u

.)

Correlation of QH and energy gap between pyrrole HOMO and two-component LUMO

HOMO

LUMO

pyrrole bridge-iminium (two-component system)

NH CH=NH2+

qLUMO

partialcharge transfer

QHQH

• Through-bond intramolecular charge transfer (ICT)

Correlation of binding energy and molecular electrostaticpotential (MEP) of the two-component system

CH=NH2+

MEPQ = +1

• Through-space electrostatic effect important when ICT is absent

Model construction

HOMO

LUMO

pyrrole bridge-iminium (two-component system)

NH CH=NH2+

qLUMO

partialcharge transfer (C=C)n-iminium

(N=N)n-iminium

21

12

Signal reduction

Signal maintaining

-16

-14

-12

-10

-8

-6

-4

-2

0

2

4

6

8

H2C NH2+ H N N H

2H N N H

4H2C NH2

+ HHC C

HH

4H

HC C

HH

2

En

erg

y (

eV

)

Bridge effect on two-component LUMO

Better bridge: Low-lying -HOMO and -LUMO

• Confirmed by three-component systems containing CF=CF units

Table 1. Ammonia binding energies (kcal/mol) with three-component systems at the HF/6-31G* level

n C=C(N) C=C(P) CF=CF(N) CF=CF(P)

1 -6.84 -13.17 -7.07 -14.00 2 -6.73 -12.04 -7.27 -13.31

3 -6.64 -11.18 -7.38 -12.82

4 -6.57 -10.47 -7.54 -12.51

Hwang, T.-S. et al. Chem. Eur. J., accepted.

• CF=CF superior in terms of signal maintenance and signal sensitivity.

Ammonia binding energy of protonated pyrrole-(X=X)n-imine

(C=C)n

(N=N)n

(C=N)n

(N=C)n

-20

-18

-16

-14

-12

-10

-8

1 2 3 4

n

Bin

din

g E

ner

gy (

kca

l/mol

)

(C≡ C)n

• Introduction of N lowers /* orbital energies, but orientation important.

(C=C-N=N)n

(C=C-C=N)n

(C=C-N=C)n

(N=N-C=C)n

(C=N-C=C)n

(N=C-C=C) n

(N=N-C=N)n

(N=N-N=C)n

(C=N-N=N)n

(N=C-N=N) n

-20

-18

-16

-14

-12

-10

-8

1 2

n

Bin

din

g E

ner

gy (

kca

l/mol

)Ammonia binding energy of protonated

pyrrole-(X=X-X=X)n-imine

• Introduction of N lowers /* orbital energies, but orientation important.

Recent success in employing a remote charge center to affect hydrogen bonding

Sessler, J. L. et al. J. Am. Chem. Soc. 2002, 124, 1134.

N

N

N

N

N

N N

N

N

N

NH

NHRuN

N

N

N

N

N N

N

N

N

NH

NHCo

+2 +3

N

N N

N

N

N

NH

NH

Ka(F-; DMSO) = 440 M-1

Ka(F-; DMSO) = 12000 M-1 Ka(F

-; DMSO) = 54000 M-1

Conclusion

• Coupled with experimental evidences, remote control of hydrogen bonds by charge alteration is feasible.

• A model is established to understand the signal reduction/maintaining phenomenon. A bridge with low-lying -HOMO and -LUMO is expected to facilitate the signal amplifying behavior.

• Orientation of the bridge is important.

• Limited structure units can be used to construct bridges of very different properties.

Acknowledgement

黃聰松 阮寧 陳信允 陳政仲 駱思融＄＄＄國科會、中央研究院