THE STRUCTURE OF PHENYLGLYCINOL A. SIMAO, I. PEÑA, C. CABEZAS, J.L. ALONSO Grupo de Espectroscopia Molecular. Unidad asociada CSIC Laboratorios de Espectroscopia y Bioespectroscopia Edificio Quifima. Parque Científico Universidad de Valladolid SPAIN

QUADRUPOLE COUPLING HYPERFINE STRUCTURE Phenylglycinol: unveiling the conformational panorama 0 cm-1 368 cm-1 116 cm-1 QUADRUPOLE COUPLING HYPERFINE STRUCTURE I III II 14N V IV AROMATIC AMINO ALCOHOL 674 cm-1 707 cm-1 HIGH FLEXIBILITY MP2/6-311++G(d,p) level of theory

Phenylglycinol: experimental strategy Broadband CP-FTMWspectroscopy + laser ablation source EFFICIENT CONFORMATIONAL SEARCH Rotational constants: A, B, C 14N 2. Narrowband LA-MB-FTMW spectroscopy Sub-doppler resolution Nuclear quadrupole coupling constants: aa, bb, cc

+ CP-FTMW experimental setup CP-FTMW spectroscopy Laser Ablation (LA) Broadband FT-MW spectrometer Supersonic Expansion 6-18 GHz S. Mata I. Peña, et al. J. Mol. Spectr. 280 (2012) 91–96 Picosecond Laser

CP-FTMW experimental setup Ne Rotary Diffusion pump Nd:YAG laser

CP-FTMW experimental setup Gas pulse Jet Ne Laser pulse Solid sample Rotary Diffusion pump Laser Nd:YAG laser

CP-FTMW experimental setup spectrometer Gas pulse MW field Polarization Ne Laser pulse Chirped MW pulse Rotary Diffusion pump

CP-FTMW experimental setup spectrometer Gas pulse Molecular emission Ne Laser pulse Chirped MW pulse Rotary Diffusion pump Detection Detection Frequency-domain Time-domain FT

LA-MB-FTMW experimental setup Laser Ablation Molecular Beam Fourier Transform Microwave Spectroscopy * LA-MB-FTMW J. L. Alonso et al. PCCP 11 (2009) 617–627

Phenylglycinol: Rotational spectra J’J’’= 5 4 6 5 7 6 8 7 14N B + C  1435 MHz Intense a-type R-branch progressions Rotamer assigned LA-MB-FTMW CP-FTMW

SEARCHING FOR THE SECOND CONFORMER… Phenylglycinol: Results Theory Experiment   I II III IV V Rotamer Aa 3085.2 3053.6 3019.7 2255.3 2459.5 3087.32251(76)g B 735.7 757.9 756.9 936 918 738.36002(24) C 700.9 700.2 699.2 804.3 838 700.88602(25) χaa -4.54 1.35 1.14 1.91 -0.41 -4.2691(46) χbb 2.27 -0.82 -0.84 1.59 -0.6 2.2247(54) χcc -0.53 -0.31 -3.49 1.01 2.0444(54) a -2.8 1 0.3 Observedf b 0.9 -1.7 -1 Observed c 1.4 -0.7 1.3 -0.2 ΔEb 115 330 773 678 - ΔGc 116 368 674 707 d 2.6 Ne 40 SEARCHING FOR THE SECOND CONFORMER… OHN NH H-bonds [a] A, B, and C represent the rotational constants (in MHz), |µa|, |µb| and |µc| are the absolute values of electric dipole moment components (in D). [b] Electronic energies including zero-point energy correction (in kJmol-1). [c] Gibbs energies calculated at 298 K. [d] Rms deviation of the fit. [e] Number of fitted transitions. [f] Standard error in parenthesis in the units of the last digit. [g]Observation of a-, b-, and c-type transitions for each structure.

Phenylglycinol: Isotopic species 13C and 15N isotopologues in natural abundance of the rotamer observed CP-FTMW

Rotational Constants (MHz) Phenylglycinol: rs structure Rotational Constants (MHz) Isotope aA B C 13C2 3061.52(60)b 733.2767(2) 697.0554(4) 13C3 3073.20(42) 736.5844(2) 699.4181(3) 15N4 3042.441(3) 733.0243(3) 697.1060(5) 13C6 3057.35(81) 736.93381(9) 698.2853(2) 13C7 3054.22(20) 731.8173(1) 693.8106(2) 13C8 3084.80(101) 728.5411(7) 692.0986(6) 13C9 3058.03(27) 732.9438(1) 694.8334(2) 13C10 3063.47(19) 737.5659(9) 699.0628(2) C4 C5 C9 C10 C1 N2 O1 C17 C3 C8 Substitution coordinates a b c C3 1.248(28) -0.17(20) 0.31(11) C4 -1.083(10) -1.232 (22) 0.395(72) C5 -2.479(13) -1.115 (29) 0.13(26) C8 -3.027(9) 0.16 (22) -0.31(11) C9 -2.178(10) 1.245(35) -0.580(79) C10 -0.690(2) 1.176(40) -0.533(93) C17 2.013(5) -0.24(17) -0.840(50) N2 1.802(5) 0.8125(20) 1.3474(12) rs structure r(C4-C5) 1.426(58)a  C4C5C8 119.7(46) r(C5-C8) 1.46(21) C8C9C10 124.4(62) r(C8-C9) 1.40(18) C5C8N2 120.4(27) r(C9-C10) 1.489(72)

Conclusions Detection of one rotamer of neutral phenylglycinol, which is stabilized by an OH∙∙∙N bond, within the ethanolamine moiety, and one NH∙∙∙π bond with the phenyl ring The high sensitivity reached with this experimental approach, based on a parabolic reflector system, has allowed the observation of eight monosubstituted isotopic species in natural abundance for the most stable conformer The combination of CP-FTMW and LA-MB-FTMW represents an excellent experimental approach to face the challenge of investigating biological systems with an expected rich conformational behavior

CSD 2009-00038 Molecular Astrophysics ACKNOWLEDGMENTS Grupo de Espectroscopia Molecular (GEM) Laboratorios de Espectroscopia y Bioespectroscopia, Unidad Asociada CSIC, UVa,Valladolid, Spain Grants CTQ 2010- 19008, AYA 2009-07304 and AYA 2012-32032 CSD 2009-00038 Molecular Astrophysics Grants VA070A08 and CIP13/01