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 8523 - PhLAM - Physique des Lasers Atomes et Molécules, University of Lille, CNRS, F-59000 Lille, France.

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

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

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 6-311++G(d,p)a 0.03 2.7 1.4 4.3 6-311++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

MB-FP-FTMW Spectroscopy Spectral range: 1,7-20 GHz High resolution: FWHM~15 kHz Sensibility : 10-10 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. 517-518, 375 (2000) ; M. Tudorie, et al. J. Chem. Phys., 134 (2011), p. 074314 ISMS – june 2018

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 1520.225823(63) -0.3% -0.5% B /MHz 1097.367672(37) -1.0% -0.4% C /MHz 983.704765(33) -0.1% -0.6% ΔJ /kHz 0.04410(35) 15.8% 10.0% ΔJK /kHz -0.0294(17) -25.5% -69.0% ΔK /kHz 0.0567(20) -3.7% -25.7% δJ /kHz 0.00626(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 1494.88444(30) -0.4% -0.5% B /MHz 1201.81175(13) -0.6% -0.8% C /MHz 901.905933(74) ΔJ /kHz 0.0285(12) -69.5% -67.4% ΔJK /kHz - -0.0561 -0.0572 ΔK /kHz 0.035(14) 33.7% 28.0% δJ /kHz 0.00626(71) 42.5% δK /kHz 0.023 0.024 N 42 transitions RMS=1.2 kHz 7 5 3 - 6 4 3 4 2 2 - 3 2 1 ISMS – june 2018

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

Endo-Fenchol with Deuterated hydroxyl 1EF 2EF R(OH) is shortened for 1EF H/D Coordinate Experiment MP2/6-311++G(d,p) Angström rs 1EF 2EF a ±0.6395 (24) 0.655 0.552 b ±2.4853 ( 6) -2.582 -2.574 c ±0.9463 (16) -0.670 -0.752 ISMS – june 2018

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

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

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

Complex Endo-fenchol – H2O Constant Exp. (G.S.) MP2 (3EF-1w) 6 -311++G(d,p) A /MHz 1210.91654(14) 1225.6 B /MHz 752.900591(78) 761.4 C /MHz 622.335817(60) 630.0 ΔJ /kHz 0.08308(31) - ΔJK /kHz 0.2412(29) ΔK /kHz -0.1445(18) δJ /kHz 0.01321(17) δK /kHz 0.0619(33) N 95 transitions RMS 1.7 kHz One conformer was observed ISMS – june 2018

Multi-substitution for endo-fenchol - Water EF-OD:HOD EF-OD:D2O EF-OH:D2O EF-OD:DOH A 1196.021(48) 1192.798891(25) 1202.305271(186) 1197.529(101) 1207.277(38)  B 729.3244(77) 721.0172439(21) 724.4326151(13) 740.386(47) 744.0156(183)  C 606.17071(21) 599.7652761(61) 600.8098827(6) 614.3077(131) 615.4451(51)  rs structure ISMS – june 2018

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

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

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-0005-01), 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