Electronic spectra of calix[n]arene and its van der Waals clustersin supersonic jetsT. Ebata, k. Nishimoto, N. Hontama, and Y. InokuchiChemistry Department, Hiroshima University, Japan Cyclodextrine Crown-ether Calixarene BiomoleculeKey interaction: noncovalent interaction. However: The binding energy of the interaction is comparable to the thermal energy at room temperature. Limited information of averaged structureAbilities of Transfer metal ion between two different phasesDiscrimination of chirality of chiral moleculePhotochemical switchPurpose: Detailed study on guest-host interaction leading molecular recognition.

Four phenol molecules are connected by methylene groups. The molecule can encapsule many type of molecule(s) through van der Waals (or H-bond) interaction.Study on encapsulation of guest-molecule(s) by calixareneCalix[4]arene (C4A)Electronic states Four electronic states are degenerated (Lowest electronic state) Four OH group are strongly H-boned (IR spectrum) Encapsulation of different kind of atoms and molecules. (Reveal the intrinsic nature of encapsulation)

How do we obtain the supersonic jet of calix[n]areneMelting point of L-Phe is 315 It is necessary to vaporize the sample without thermal decomposition.

(1) Heating nozzle : Use of metal-free nozzle(2) Laser ablation nozzle: Difficulty of shot-to-shot stabillity to obtain the UV and IR spectra.Heating nozzle Laser ablation

Electronic states of C4ADipole transition under C4symmetryLIF0,0xy0.0 band? ? ?

Calix[4]arene(C4A)-M clustersC4AC4A-ArnC4A-(N2)nC4A-(CH)nC4A-(H2O)10,035357C4A can easily form van der Waals clusters

Electronic spectra of Calix[4]arene-Arn clusters A partial pressure of Ar as low as 0.4 % is large enough for complete clustering !

Red-shift of the 0,0 bandStructure of Calix[4]arene - Arn ,Nen clusters

Red-shift of C4A-Mn=1 vs. polarizabilityNeArN2CH4a (3)For Ne and Ar as a guest, the red-shift is in proportional to polarizability.On the other hand, the red-shift is very sensitive to the orientation of the guest molecule. Red-shift of the 0,0 band of C4A-Nen, -Arn, -N2nStructure of Calix[4]arene - Arn Nen, (N2) n clusters Large difference

Calix[4]arene(C4A)-M clustersC4AC4A-ArnC4A-(N2)nC4A-(CH)nC4A-(H2O)10,035357C4A can easily form van der Waals clusters

Ab initio calculated structure of C4A-H2O( HF/3-21G )0 cm-1+2322 cm-1+3180 cm-1+4353 cm-1

Most stable structure Calculated IR spectrum Structure of Calix[4]arene-(H2O)1Water is involved in the H-bonding network of C4AFree OH stretch of waterIR-UV double resonance spectroscopy is in progress

Encapsulation ability of C4APartial pressure of ArCalix[4]arene-Arn2,6-dimethylphenol-Arn25Ar/He(%)1230.370.093%HeNo van der Waals bandC4A has a high ability of encapsulatingatom and moleculeHow large is the binding energy ?

LIF1+1 REMPITime-of-FlightBinding energy of C4A-(Ar)nIP0

C4AC5ASummaryLaser Spectroscopy has been successfully applied to jet-cooled Calix[4]arene(C4A).S1 state is 1A ,under C4 point group.S1 state is strongly vibronically coupled with upper S2(1E) state. C4A has a high ability of encapsulating a hydrophobic molecule.The electronic spectrum of C4A is very sensitive to the anisotropy of guest molecule. C4A Ar C4A N2

Future workDetermination of binding energy inside/outside the cavity. Elucidation of encapsulation structure of various guest molecule(s).Extension to larger size calixarene(C5A, C6A) and different type of calixarene (resolcin arene).

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