C…H…N hydrogen bond formation in trimethylamine dimer upon one-photon ionization Yuichiro...
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C…H…N hydrogen bond formation in trimethylamine dimer upon one-photon ionization Yuichiro Nakayama, Yoshiyuki Matsuda, and Asuka Fujii Department of Chemistry, Graduate School of Science, Tohoku University, Japan
C…H…N hydrogen bond formation in trimethylamine dimer upon one-photon ionization Yuichiro Nakayama, Yoshiyuki Matsuda, and Asuka Fujii Department of Chemistry,
CHN hydrogen bond formation in trimethylamine dimer upon
one-photon ionization Yuichiro Nakayama, Yoshiyuki Matsuda, and
Asuka Fujii Department of Chemistry, Graduate School of Science,
Tohoku University, Japan
Slide 2
Introduction Most stable cation NeutralProton-migration VUV
photoionization Matsuda et al. Angew. Chem. Int. Ed. 49, 4898
(2010) Keto-enol tautomerization in the VUV photoionization of the
acetone-water cluster Proton-migration from a methyl group Does a
cationic alkyl group act as proton donor and/or H-bond donor? A
neutral alkyl group generally does not act as a proton donor
Slide 3
This study Understand the ability of the cationic methyl group
as H-bond donor Aim Exp. & Calc. IR spectroscopy of (TMA) 2 and
(TMA) 2 + through the VUV photoionization detection Theoretical
calculations of structures, harmonic vibration, and potential
energy curves of the cationic state Trimethylamine (TMA) dimer
cation TMA has only the methyl groups and nitrogen. Sample
Slide 4
Experiment IRPDS-VUV-PI (IR Predissociation Spectroscopy of
VUV-Pumped Ion) VUV-ID-IRPDS (VUV-Ionization-Detected IR
Predissociation Spectroscopy) Matsuda et al. Phys. Chem. Chem.
Phys. 11, 1265 (2009) IR spectroscopy for neutral clusters IR
spectroscopy for cationic clusters We can observe IR spectra of
both neutral and cationic clusters
Slide 5
IR spectrum of neutral (TMA) 2 The most stable structure
VUV-ID-IRPDS
Slide 6
IR spectrum of (TMA) 2 + A broad H-bonded X-H stretch band is
observed
Slide 7
Energy Diagram of the reaction of (TMA) 2 + AIE (CH-N) H +
-transfer-type I Most stable Zero point energy 1.3 kcal/mol
Vertically ionized structure Energy (kcal/mol) Intrinsic Reaction
Coordinate ( 1/2 ) AIE (C-HN) H-bond-type Coexistence of two
structures
Slide 8
Isomerization reaction of (TMA) 2 induced by photoionization A
proton is shared between C and N A methyl group acts as a
hydrogen-bond donor in the cationic state VUV One-photon ionization
NeutralCation
Slide 9
Summary VUV One-photon ionization NeutralCation We observed the
IR spectra of (TMA) 2 and (TMA) 2 + with spectroscopies based on
the VUV photoionization detection. We calculated the isomerization
reaction potential energy curve following the one-photon
ionization. In the VUV photoionization process, (TMA) 2 is
isomerized to the structure in which a proton is shared between C
and N. In this structure, the methyl group acts as the proton
donor.