Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in...
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![Page 1: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/1.jpg)
Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters
Asuka Fujii, Ken-ichiro Suhara, Kenta Mizuse, Naohiko Mikami
Jer-Lai Kuo
Department of Chemistry, Graduate School of Science, Tohoku University, Japan
School of Physical and Mathematical Sciences,National Nanyang Technological University, Singapore
![Page 2: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/2.jpg)
Hydrogen bond network structures in protonated clusters
Mass spectrometry
IR dissociation spectroscopy of size-selected cluster cations (Y. T. Lee, 1989)
ab initio and MD calculations
direct probing of the H-bond network structure
size distribution and magic numbers
Network structure in large-sized clusters
• microscopic picture of protic solvents
• proton motion in liquids
• nature of hydrogen bond, ….. , etc.
![Page 3: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/3.jpg)
3-dimensional (3-D) cage formation in H+(H2O)21
magic number at n=21 dominance of the 3-coor-dinated water at n=21
mass spectrum IR spectrum of free OH
ADAAD
FennHagenNishiCastleman Jr.
MikamiDuncan,Johnson,JordanChang
(1974-91)(2004-5)
3-D cage formationof the hydrogen bond network
![Page 4: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/4.jpg)
Network development in protonated methanol clusters
IR spectroscopy of H+(MeOH)n
n=4&5 Chang et al. (1999) linear chain to cyclic at n=5
n=4-15 Fujii et al. (2005) bicyclic structure in n>6
IR spectra of n=4-15
bicyclic structure at n=7
terminal of the network development
no more complicated cage structure
![Page 5: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/5.jpg)
Hydrogen bond network in protonated water-methanol mixed clusters
water : 4-coordination, complicated cage
methanol : 3-coordination, simple network
hydrogen bond network in the mixed system?
What really happens in aqueous alcohol ?
![Page 6: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/6.jpg)
IR spectroscopy of H+(MeOH)m(H2O)n (@Sendai)
m=1-4, n=4-22 (m<<n)
This study
(the case of m>>n :FD05 by K. Suhara)
DFT calculations of the relative stabilities of isomer structures (@Singapore)
model systems : (MeOH)m(H2O)n (m+n=8) and H+(MeOH)1(H2O)20
Microscopic compatibility between methanol and water in H-bond network formation
![Page 7: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/7.jpg)
MeOHH2O
Ne
PulsedValve
UV laser(355 nm)
-300V
Experiment
IR dissociation spectroscopy of size-selected clusters
laser-assisted discharge nozzle
pick-up type ion source(clusters are formed frombare cations)
H+MmWn
H+MmWn-1 + W
H+MmWn-2 + 2Wor
IRv=0
v=1
![Page 8: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/8.jpg)
Mass spectrum of H+(MeOH)m(H2O)n mixted clusters
magic number at m+n=21
(sudden intensity decrease at m+n=22)
3-D cage formation similar to protonated water ?
(Castleman et al., 1992)
the same behavior as protonated water
Cage structurefor NH4
+(H2O)20
(Johnson&Jordan,2005)
![Page 9: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/9.jpg)
Infrared spectra of H+(MeOH)2(H2O)n
OH stretching vibrational region
H-bonded OH stretch :broadened
free OH stretch : more informative
![Page 10: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/10.jpg)
Infrared spectra of H+(MeOH)2(H2O)n in the free OH stretch region
AAD AD2-coordinated
AD (acceptor-donor) site
3-coordinated
AAD (double-acceptor-single-donor) site
3715 cm-1
3695 cm-1
dominance of theAAD (3-coordinated) sites
3-D cage formationat n+m=21
![Page 11: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/11.jpg)
Cluster size dependence of the intensity ratio of the AD/AAD bands
Similar size dependencebetween protonted water and protonated mixed clusters
the same 3-D cageformation at the same cluster size
Compatible behavior of small number of methanolmolecules with water in the H-bond network
![Page 12: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/12.jpg)
Theoretical confirmation of the microscopic compatibility
model system : neutral (H2O)8
DFT evaluation of the relativestabilization energies (B3LYP/6-31+G*)
(MeOH)4(H2O)4
smallest polyhedral cage (cube)
14 orientational isomers
substitution of all the AAD sites with methanol
![Page 13: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/13.jpg)
Relative stabilities of the orientational isomers in (H2O)8 and (MeOH)4(H2O)4
(numbering of the isomers)
Clear correlation between (H2O)8 and corresponding (MeOH)4(H2O)4
Compatibility between methanol and AAD water
![Page 14: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/14.jpg)
3-D caged structures and the proton location of H+(MeOH)1(H2O)20
DFT energy optimization (B3LYP/6-31+G*) of minimasearched by Monte Carlo methodswith empirical model potentials
the excess proton
Proton transfer occurs if the optimizationstarted with the MeOH2
+ core
preference to the surface water site
proton migration in spite of the largerproton affinity of methanol
![Page 15: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/15.jpg)
Summary
IR spectroscopy of H+(MeOH)m(H2O)n (m=1-4, n=4-22) in the OH stretch region
Spectroscopic evidence for the 3-D cage formation of the mixed clusters at the magic number m+n=21 (m=1-4)
Microscopic compatibility between methanol and AAD water in the H-bond network development
DFT calculations also support the compatibility in the relative energy
The excess proton prefers the surface water site in the (1+20)-mer indicating the proton migration from methanol to water
![Page 16: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/16.jpg)
Microscopic compatibility in (MeOH)m(H2O)n (m+n=8)
Energy correlation between isomersof (H2O)8 and (MeOH)m(H2O)8-m
![Page 17: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/17.jpg)
Preference of the protonated site
Model system : H+(MeOH)1(H2O)7
Clear preference of the water sitein the cubic isomers (90 isomers)
The MeOH2+ ion core is only stable
in the non-cubic isomers.
![Page 18: Microscopic Compatibility between Methanol and Water in Hydrogen Bond Network Development in Protonated Clusters Asuka Fujii, Ken-ichiro Suhara, Kenta.](https://reader036.fdocument.pub/reader036/viewer/2022062422/56649f2c5503460f94c472bf/html5/thumbnails/18.jpg)