Int. Symp. Mol. Spectrosc.　(June 21-25, 2010)

Laser Spectroscopic Study on Encapsulation Structure of Functional Molecules in Supersonic Jets

Laser Spectroscopic Study on Encapsulation Structure of Functional Molecules in Supersonic Jets

Universite de Paris-SudProf. Christophe JouvetProf. Claude Dedonder-Lardeux

Pacific Northwest National LaboratoryProf. Sotiris Xantheas

Prof. Yoshiya InokuchiMr. R. Kusaka(D2) (Crown Ether)Mr. N. Hontama Mr. S. Kokubu (M2) (Crown Ether)Mr. Shouhei Kaneko (M1) (C4A)

Takayuki EbataDept. of Chemistry, Graduate School of Science, Hiroshima University

H2O@DB18C6 H2O@C4A

Ar, CH4, C2H2

H2O, NH3,

Structure of C4A-X (X=rare gas,CH4, H2O, NH3, H2O, H2O, ) complexes

1. Which isomer (endo- or exo-isomer) do the complexes form?2. What is the main interaction (dispersion, H-bonding etc.) to form the complex.3. Relationship between the electronic transition and the structure.4. Design of the molecule having better encapsulation performance.

Endo-complex

Exo-complexCalix[4]arene (C4A)

◎ Laser spectroscopic study for jet-cooled complexes ◎ Quantum chemical calculation (MP2, CCSD,DFT(B3LYP, M05-2X) )

guest

Calix[4]arene(C4A)-M complexes

C4A

C4A-Ar

C4A-N2

C4A-CH ４

C4A-H2O

0,0

35357

C4A can easily form complexes with hydrophobic as well as hydrophilic molecules

Red-shifts and the structures of the complexes

Endo-structure

C4A-Ar

Binding energy (De) of C4A-Ar (inside, outside)

species De / cm-1

MP2/aug-cc-pVQZ

De / cm-1

CCSD(T)/aug-cc-pVQZ

EXP. / cm-1

Endo-C4A-Ar 2328 (1561) 350-2250

Exo-C4A-Ar 762 　 　 (511)

Benzene-Ar 578 　 388 　 314±7

Phenol-Ar 613 　 411 364±13

BSSE corrected

Endo(inside)-isomer Exo(outside)-isomer

De of endo-isomer is 3 times larger than the exo-isomer

PCCP, 12, 4569 (2010)

S1-S0 1 + 1 REMPI spectra

Structure of C4A-H2O, NH3

Low freq. vibrations

IR-UV Double Resonance spectra of C4A and C4A-H2O

3

CH stretch

H-bonded OH

3(H2O)1(H2O)

(a) endo-isomer

(b) exo-isomer

Determination of C4A-H2O structure from the IR spectrumDetermination of C4A-H2O structure from the IR spectrum

55 cm-1 red-shiftedfrom free 3

0 cm-1

1100 cm-1

MP2/aug-cc-pVQZ

Binding Energy of C4A-H2O

endo-isomer 3127 cm-1

(MP2/aug-cc-pVQZ level and BSSE-corrected)

exo-isomer 1985 cm-1

3140

JPCA, 114, 1967 (2010)

S1-S0 1 + 1 REMPI spectra

The spectrum of C4A-NH3 resembles C4A-H2O

Structure of C4A-NH3

IR-UV spectrum of C4A-NH3 in the OH stretch regionIR-UV spectrum of C4A-NH3 in the OH stretch region

C4A-NH3C4A-NH3

C4A-NH3 has the endo-complex structure (M05-2X/6-31+G*)

M05-2X/6-31+G*

M05-2X/6-31+G*

Binding Energy (BE) of C4A-NH3

C4A fragment monitor

2810

Both C4A - H2O and C4A – NH3 are bound by Dipole-Dipole interaction

(NH3)= 1.4 Debye < (H2O)= 1.8 Debye

(C4A)= 2.37 Debye

BE(C4A-NH3) < 2810 cm-1 BE(C4A-H2O) = 3140 cm-1<

Structure of C4A-C2H2

endo-isomer exo-isomer

MP2/aug-cc-pVDZ

Endo-isomer is 11.7 kcal/mol (4100 cm-1) is more stable than the exo-isomer

Side-viewSide-view

3.70 A

3.83 A

In the endo-isomer, the O--O bond distance is shortened by the CH--H-bonding.

Endo

IR spectrum and the structure of C4A-C2H2

Top view

3.77 A

3.77 A

Exo

Summary

Structure, electronic spectra and IR spectra of Calix[4]arene(C4A) complexes

have been investigated by various laser spectroscopic methods and quantum

chemical calculations(MP2, CCSD, DFT).

C4A encapsulates hydrophobic as well as hydrophilic molecules in its cavity.

◎ C4A-Arn:

BE(endo-C4A-Ar) = 1560 cm-1 ( 3-4 times larger than that of Bz—Ar)

n>2 : C4A encapsulates large size Arn clusters

◎ C4A-H2O ,-NH3 : The complexes are bound by dipole-dipole interaction.

“World’s smallest cup of water”

◎ C4A-C2H2 , N2 : The guest species lies perpendicular to the C4 axis.