1. Elias M. NEEMAN and Thérèse R. HUET
Isotopic substitutions unveiled the identification of the most stable conformer of fenchol and of its water complex
Elias M. NEEMAN and Thérèse R. HUET
UMR PhLAM - Physique des Lasers Atomes et Molécules, University of Lille, CNRS, F Lille, France.

2. Atmospheric interest Some facts about BVOCs: Aerosol Formation
BCOVs lifetime is short
Play a major role in atmospheric chemistry
Oxidation and degradation products – complexity
Rare information's studies concerning monoterpenes in gas phase ((C5H8)n, n>1)
Fenchol
+ Humidity
Secondary VOCs
Oxidation
O3 NOx OH
VOCs Emission
≈ 1150 TgC.yr -1
≈ 100 TgC.yr -1
Isoprene
Monoterpene
Singer, B. C. et al. Atmos. Environ. 40, 2006, 6696−6710.
Rizzo, L. V. et al. J. Atmos. Environ. 2010, 44, 503−511.
Hoffmann, T. et al. J. Atmos. Chem. 1997, 26, 189−222.
Kotzias, D. et al.. Environ. Chem. 1989, 20−1, 95−99.
Biogenic
Anthropogenic
ISMS – june 2018

3. Fenchol Chemical formula (C10H18O).
Emitted into the atmosphere by several biogenic sources.
Emitted also by panel fibers.
Exist as tow stereoisomers endo- et exo-fenchol.
Scan de SEP
MP2/6-311g
N. Yassaa et al. Atmospheric Environment, 34(17) : 2809–2816, 2000.
AG McDonald et al. Holz als Roh-und Werkstoff, 62(4) : 291–302, 2004.
Melissa GD Baumann et al. Forest products journal, 50(9) : 75, 2000.
ISMS – june 2018

4. Fenchol Results of several optimizations Endo-fenchol Exo-fenchol
Endo-fenchol
Exo-fenchol
MP2/Basis set
1EF
2EF
3EF
1XF
2XF
3XF
6-311G
0.7
0.0
4.5
0.8
5.0
G(d,p)a
0.03
2.7
1.4
4.3
G(2df,p)a
0.2
2.4
1.2
3.6
cc-pVTZ
0.3
1.9
aug-cc-pVTZ
2.0
1.3
3.4
(a) including ZPE correction
ISMS – june 2018

5. MB-FP-FTMW Spectroscopy
Spectral range: 1,7-20 GHz
High resolution: FWHM~15 kHz
Sensibility : cm-1
Accuracy : < 1 kHz
Trot = 1-5 K
π/2 condition:
τ= π 2 ħ με
Pulsed supersonic jet of a gas mixed with Neon
Interaction between the microwave pulse and the jet, associated with a maximal macroscopic polarization at π/2 condition
Relaxation of the mixture and detection of the decay of this polarization with time (FID).
Treatment of the signal by Fourrier transform operation to obtain the spectrum as a function of frequency
A high finesse cavity enhances the signal => 2 Doppler components
S. Kassi et al. J. Mol. Struct , 375 (2000) ; M. Tudorie, et al. J. Chem. Phys., 134 (2011), p
ISMS – june 2018

6. Results : fenchol Exo-fenchol Endo-fenchol SPFIT / SPCAT.
Fenchol (Sigma-Aldrich ≥ 96%)
Heated nozzle 373 K
4.5 bars of Ne
Repetition rate 1,5 Hz
Endo-fenchol
1 or 2E-F ???
Exo-fenchol
1XF
SPFIT / SPCAT.
Semi-rigid Watson’s Hamiltonian A reduction (J = 8 and Ka = 4).
SPFIT / SPCAT.
Hamiltonien semi-rigide de Watson dans la réduction (A) (J = 9 and Ka = 5).
Constant
Exp. (G.S.)
MP2 (1EF)
MP2 (2EF)
A /MHz
(63)
-0.3%
-0.5%
B /MHz
(37)
-1.0%
-0.4%
C /MHz
(33)
-0.1%
-0.6%
ΔJ /kHz
(35)
15.8%
10.0%
ΔJK /kHz
(17)
-25.5%
-69.0%
ΔK /kHz
0.0567(20)
-3.7%
-25.7%
δJ /kHz
(17)
20.1%
15.2%
δK /kHz
0.1364(26)
42.9%
23.4% N
114 transitions
RMS=1.5 kHz
Constant
Exp. (G.S.)
MP2 (1XF)
MP2 (2XF)
A /MHz
(30)
-0.4%
-0.5%
B /MHz
(13)
-0.6%
-0.8%
C /MHz
(74)
ΔJ /kHz
0.0285(12)
-69.5%
-67.4%
ΔJK /kHz -
ΔK /kHz
0.035(14)
33.7%
28.0%
δJ /kHz
(71)
42.5%
δK /kHz
0.023
0.024 N
42 transitions
RMS=1.2 kHz
ISMS – june 2018

7. Endo-Fenchol : which conformer ?
quadrupolar hyperfine Constants D
Deuteration
144 hyperfine components analysed
ISMS – june 2018

8. Endo-Fenchol with Deuterated hydroxyl
1EF
2EF
R(OH) is shortened for 1EF
H/D Coordinate
Experiment
MP2/ G(d,p)
Angström rs
1EF
2EF a
± (24)
0.655
0.552 b
± ( 6)
-2.582
-2.574 c
± (16)
-0.670
-0.752
ISMS – june 2018

9. Conformer 2EF is observed
Endo-Fenchol : 1EF/2EF OH
Exp.
1EF
2EF
B-C (MHz)
113.7
123.6
112.7 OD
Exp.
1EF
2EF
B-C (MHz)
123.3
134.8
124.1
Exp.
1EF
Conformer 2EF is observed
2EF
ISMS – june 2018

10. Complex Endo-fenchol – H2O
2EF
1EF
3EF
Which conformer will complex with water ???
ISMS – june 2018

11. Complex Endo-fenchol – H2O Conformational change due to water ???
Quantum chemical calculations for all the possible conformers
1EF-1w
1.5 kJ/mol
3EF-1w
0 kJ/mol
2EF-1w
3.3 kJ/mol
1EF-1w’
2.5 kJ/mol
Conformational change due to water ???
ISMS – june 2018

12. Complex Endo-fenchol – H2O
Constant
Exp. (G.S.)
MP2 (3EF-1w)
G(d,p)
A /MHz
(14)
1225.6
B /MHz
(78)
761.4
C /MHz
(60)
630.0
ΔJ /kHz
(31) -
ΔJK /kHz
0.2412(29)
ΔK /kHz
(18)
δJ /kHz
(17)
δK /kHz
0.0619(33) N
95 transitions
RMS
1.7 kHz
One conformer was observed
ISMS – june 2018

13. Multi-substitution for
endo-fenchol - Water
EF-OD:HOD
EF-OD:D2O
EF-OH:D2O
EF-OD:DOH A
(48)
(25)
(186)
(101)
(38)  B
(77)
(21)
(13)
(47)
(183)  C
(21)
(61)
(6)
(131)
(51) 
rs structure
ISMS – june 2018

14. Conformational change
rs structure of water hydrogens in Green
Calculated structure of water hydrogens in silver
3EF-1w is the observed conformer
ISMS – june 2018

15. Conclusion
Microwave spectroscopy combined with quantum chemistry calculations is a powerful tool for studying molecular structure in the gas phase.
We have unveiled the gas-phase structure of fenchol, by studying the deuterated species.
In this study we unveiled also the structure of the complex endo fenchol - Water.
The observed water complex is associated with the highest energy isolated conformer.
Our conclusion are confirmed experimentally.
ISMS – june 2018

16. It is a contribution to the CPER research Project CLIMIBIO.
The present work was funded by the French ANR Labex CaPPA through the PIA (contract ANR-11-LABX ), by the Regional Council Hauts de France, by the European Funds for Regional Economic Development, and by the French Ministère de l’Enseignement Supérieur et de la Recherche.
It is a contribution to the CPER research Project CLIMIBIO.
ISMS – june 2018