1. THE MICROWAVE STUDIES OF GUAIACOL (2-METHOXYPHENOL), ITS ISOTOPOLOGUES & VAN DER WAALS COMPLEXES Ranil M. Gurusinghe, Ashley Fox and Michael J. Tubergen, Department of Chemistry, Kent State University, Kent, Ohio 44242.

2. Motivation Intramolecular hydrogen bonding & conformational preferences Conformational changes upon forming van-der-Waals complexes :  Ar complex  Water complex GUAIACOL (2-METHOXYPHENOL)

3. Background Monomer2-aminoethanol-Ar 2-aminoethanol-water

4. Background Monomer Glycidol-Water

5. Guaiacol: Previous Ab initio Studies C. Agache and V. I. Popa, Monatsh. Chem. 137 (2006) 55-68

6. Previous Ab initio Studies global minimum17.57- 20.92 kJ mol -1 22.17 - 23.43 kJ mol -1 planar Non-planar Intramolecular H bond 18.09 – 18.51 kJ mol -1 -- O. V. Dorofeeva, et al., J. Mol. Struct. 933 (2009) 132-141

7. Ab initio Studies MP2/6-311++G(d,p) anti-synanti-antigauche-anti A / MHz2594.56312558.13682823.4472 B / MHz1560.73221566.93831502.1355 C / MHz981.4123977.80281037.4823 µ a / D-1.95770.7493-1.1651 µ b / D-2.3106-1.18191.3121 µ c / D0.23560.00221.4967 Relative Energy/kJ mol -1 0.0011.6416.62

8. Kent State FTMW Spectrometer Range : 10500- 22000 MHz Resolution : 2.4 kHz Carrier Gas :  He(30%)/Ne  Ar Temperature : 25 – 60 0 C Backing pressure : 1.5 atm Hydroxyl deuterated guaiacol prepared by stirring of guaiacol with D 2 O in 1:1 ratio for 48 hrs

9. Guaiacol Spectrum Experimental Results A/MHz 2607.0664(6) Δ K /kHz 0.00019(3) B/MHz 1560.7967(2) δ J /kHz 0.000021(1) C/MHz 982.8721(1) δ K /kHz 0.00011(1) Δ J /kHz 0.000056(2) N 52 Δ JK /kHz 0.000064(13) Δν rms 0.0025 Optimized anti-syn conformation Ab initio Results A / MHz2594.5631 B / MHz1560.7322 C / MHz981.4123

10. Spectroscopic Constants Normal 13 C(2) 13 C(3) 13 C(5) 13 C(7) 13 C( 8) 13 C(9) 13 C(14) 2 H(12) A/MHz 2607.0664(6)2602.9051(5) 2571.7285(6) 2580.0272(4)2606.9526(6)2594.9216(7)2600.0172(4)2598.9887(9)2546.0430(11) B/MHz 1560.7967(2)1536.0989(3) 1551.2280(2) 1560.8336(4)1559.8295(4)1559.9680(4)1545.4638(2)1525.2094(4)1555.5731(5) C/MHz 982.8721(1)972.4404(1) 974.0418(2) 979.0202(2)952.4749(1)980.8136(1)975.7804(1)967.5229(2)972.0485(2) Δ J /kHz 0.000056(2)0.000053(5) 0.000052(2) 0.000059(8)0.000032(7)0.000043(7)0.000048(4)0.000058(7)0.000089(8) Δ JK /kHz 0.000064(13)0.000057(28) 0.000058(14) 0.000063(36)0.00018(3)0.00014(3)0.000071(19)0.000010(37)0.000046(41) Δ K /kHz 0.00019(3)0.00027(7) 0.00015(5) 0.00024(80)0.00022(8)0.00020(9)0.00018(5)0.00019(7)0.00024(10) δ J /kHz 0.000021(1)0.000019(2) 0.000017(1) 0.000021(4)0.000009(3)0.000014(3)0.000016(2)0.000022(3)0.000038(4) δ K /kHz 0.00011(1)0.00011(3) 0.00008(13) 0.00015(6)0.00008(3)0.00009(3)0.00009(2)0.00017(4)0.000244(39) N 5224 28 2523272624 Δν rms 0.00250.00110.00120.00140.00120.00150.00090.0014

11. Principal-Axis-System Coordinates of 13 C and 2 H from: Kraitchman Analysis & Ab-initio Method Isotopomer KraitchmanAb-initio | a| / Å| b| / Å| c| / Å a / Å b / Åc / Å 13 C(2)2.28430.56900.00822.2967-0.59690.0290 13 C(3)1.40211.64850.0147 i1.3851-1.6541-0.0140 13 C(5)0.0904 i1.42850.02490.0045-1.3970-0.0180 13 C(7)0.44840.08850.0261-0.4478-0.0757-0.0454 13 C(8)0.41420.95530.00750.47240.99130.0109 13 C(9)1.79290.73520.02261.84010.72800.0083 13 C(14)2.74870.80020.0119-2.7409-0.69030.0642 1 H(12)1.02302.16550.0644-0.93722.23810.0314

12. Guaiacol-Ar: Ab Initio Studies MP2/6-311++G(d,p) Structure Dipole Moments / DRotational Constants / MHz Relative E/ kJ mol -1 µaµa µbµb µcµc ABC 1-1.2974-1.83232.01141065.9583874.4618751.28290.00 21.86710.54102.2914989.6771927.2382750.23710.75 3-0.31233.01540.22852097.6937526.6349422.30773.33 Optimized Guaiacol-Ar complex 1 2 3

13. Guaiacol-Ar Spectrum Experimental Results A/MHz1142.6041(14)Δ K /kHz0.01482(3) B/MHz801.1291(7)δ J /kHz0.000669(1) C/MHz705.8670(1)δ K /kHz-0.002499(12) Δ J /kHz0.002594(3)N43 Δ JK /kH z -0.007886(24)Δν rms 0.0034 Ab initio Results A / MHz1065.9583 B / MHz874.4618 C / MHz751.2829

14. Principal-Axis-System Coordinates of Ar atom from: Kraitchman Analysis & Ab Initio Method More Ab-initio modeling need to be done for Guaiacol-Ar complex KraitchmanAb –Initio | a| / Å| b| / Å| c| / Å a / Å b / Åc / Å 2.36571.13600.5282- 1.6343082.0355440.509286

15. Guaiacol-Water Complex Ab Initio Studies: MP2/6-311++G(d,p) Structure Dipole Moments / D Rotational Constants / MHz Relative E/ kJ mol -1 µaµa µbµb µcµc ABC 10.08591.9007-1.26102017.7828973.4661784.3017 0.00 2-0.2980-1.2651-0.11231490.88851091.8987944.1165 4.57 24.0033-1.3853-0.69271720.5131895.8985596.4990 6.25 4-3.1880-0.30060.54562061.0862908.5115650.8791 16.43 1 23 4

16. Summary Ab initio calculations & rotational spectra for guaiacol, its isotopologues, Ar & water complexes Lowest energy conformation of guaiacol accommodates intramolecular hydrogen bonding Guaiacol-Ar : More modeling need to be done Guaiacol-Water : Work in progress

17. Acknowledgements Ohio Super Computer Center Kent State University, Kent, Ohio

20. Principal-Axis-System Coordinates of 13 C and 2 H from: Kraitchman Analysis & Ab-initio Method Isotopo mer KraitchmanAb-initio | a| / Å| b| / Å| c| / Å a / Å b / Åc / Å 13 C(2)2.2843(6)0.5690(26)0.0082(1828)2.2967-0.59690.0290 13 C(3)1.4021(11)1.6485(9)0.0147 I(-1020 i)1.3851-1.6541-0.0140 13 C(5)0.0904 I(-165i)1.4285(10)0.0249(601)0.0045-1.3970-0.0180 13 C(7)0.4484(33)0.0885(169)0.0261(573)-0.4478-0.0757-0.0454 13 C(8)0.4142(36)0.9553(15)0.0075(1998)0.47240.99130.0109 13 C(9)1.7929(8)0.7352(20)0.0226(663)1.84010.72800.0083 13 C(14)2.7487(5)0.8002(18)0.0119(1255)-2.7409-0.69030.0642 1 H(12)1.0230(14)2.1655(6)0.0644(232)-0.93722.23810.0314

21. Guaiacol-Ar models: Structures 1 & 2 3.549 Å, 3.22 Å3.349 Å, 3.481 Å 1212

22. Hydroxyl deuterated Guaiacol Preparation Rapid stirring of guaiacol with D 2 O in 1:1 ratio for 48 hrs Filtered out the organic layer Dried in a desiccator for another 48 hours Confirmed with NMR spectroscopy