MICROWAVEWAVE SPECTROSCOPY OF 5 METHYL HYDANTOIN Hiroyuki OZEKI

MICROWAVE-WAVE SPECTROSCOPY OF 5 -METHYL HYDANTOIN Hiroyuki OZEKI 1, Minami AWADU 1, Soichiro WATANABE 1, and Kaori KOBAYASHI 2 1 Toho University, Funabashi, JAPAN 2 Toyama University, Toyama, JAPAN TG 04 74 th ISMS MINI-SYMPOSIUM: ASTROCHEMISTRY AND ASTROBIOLOGY IN THE AGE OF ALMA

Interstellar pre-biotic molecules • Amino acids • Glycine × Alanine × • Sugars • Glycoaldehyde ○ • Nucleic Acids (Building Block) • Pyrimidine, Imidazole, Pyrrole, , , ×

Motivation Possible precursors of Glycine Hydantoin C 33 H 44 N 22 O 22 Aminoacetonitrile NH 2 CN Acetolactone H 2 COCO Ammonium ylide CH 2 NH 3 Hydroxylamine NH 2 OH Aminomethanol NH 2 CH 2 OH Ap. JS 209, 23 (2013). A&A 566, A 28 (2014). Ap. JS 230, 26 (2017). A&A 600, A 44 (2017).

Hydantoins in meteorites A. Shimoyama & R. Ogasawara (2002)

Hydantoin as a precursor of di- or oligo-peptides in primitive oceans N-Carboxyanhydride amino acid Hydantoin Carbamoyl Peptides Amino acids P. Marcellus et al. (2011), A. Commeyras et al. (2004), G. Danger et al. (2006)

5 -methylhydantoin (5 -MH) (5 -methylimidazolidine-2, 4 -dione) Precursor of Alanine, the simplest chiral amino acid 5 Asymmetric Carbon

5 -MH in meteorites A. Shimoyama & R. Ogasawara (2002) It will be useful to provide spectroscopic data for future astronomical search of 5 -MH, like Hydantoin

Present Study Millimeter-wave spectroscopy of 5 -Methl. Hydantoin (5 -MH) With conventional frequency modulated spectrometer with 100 cm length free space cell @ Toho university

Preparation of Sample • 5 -MH : white powder (m. p. 450 K) • 50 grams of 5 -MH is put inside the cell Vacuum Pump heated up to 360 – 380 K

Sample Preparation • The 5 -MH sample is commercially available with a unit of 1 gram. • We have synthesized 5 -MH by the following 2 -step reaction. Tetrahedron Lett. 53. 5996, Eur J. Org. Chem. 2008, 1910

Prediction of pure rotational spectrum of 5 -MH • Very few spectroscopic studies on 5 -MH • DFT calculation has been conducted for • Molecular structure (Rotational Constants) • Dipole moment • Vibrational frequencies

Molecular structure & Dipole moment of 5 -MH (B 3 LYP/aug-cc-p. VQZ (5 d, 7 f)) A ～ 3595 MHz B ～ 1881 MHz C ～ 1309 MHz mb ～ 2. 4 D ma ～ 1. 4 D

5 -MH vs. Hydantoin 5 -MH Hydantoin A 3595 MHz 6538 MHz B 1881 MHz 2274 MHz C 1309 MHz 1709 MHz ma 1. 4 D 0. 2 D mb 2. 4 D mc 0. 7 D 0. 6 D E. R. Alonso et al. (2017)

Predicted b-type spectrum of 5 -MH @370 K 100 GHz 200 GHz 300 GHz 400 GHz

Search for b-type spectrum of 5 -MH @ 400 GHz c i l p m o c ry d e at Ve 400 GHz 410 GHz

Search for b-type R-branch spectrum of 5 -MH Series with ～ 2600 MHz separation 160 GHz 170 GHz

10 GHz Spectral line survey 160 GHz S/N is much smaller than that of Hydantoin 170 GHz

Zoom in Separation of 2634 MHz

Predicted b-type spectrum of 5 -MH Each series consist of “K-structure” with ～ 350 MHz separation 2634 MHz ～ 350 MHz 160 GHz 170 GHz

Q. N. Assignment Ka=0 -1, 1 -0 N=61 -60 N=62 -61 N=63 -62 N=64 -63

Q. N. Assignment Ka=1 -2, 2 -1 N=61 -60 N=62 -61 N=63 -62 N=64 -63

Q. N. Assignment Ka=2 -3, 3 -2 N=61 -60 N=62 -61 N=63 -62 N=64 -63

Q. N. Assignment Ka=3 -4, 4 -3 N=61 -60 N=62 -61 N=63 -62 N=64 -63

Q. N. Assignment Ka=4 -5, 5 -4 N=61 -60 N=62 -61 N=63 -62 N=64 -63

Q. N. Assignment Ka=5 -6, 6 -5 N=61 -60 N=62 -61 N=63 -62 N=64 -63

Molecular constants of 5 -MH (so far determined) • Watson type A-reduced Hamiltonian Ground state (1 s) B 3 LYP/aug-cc-p. VTZ A (MHz) 3591. 022(55) 3595 - 0. 14% B (MHz) 1886. 5165(149) 1881 + 0. 33% C (MHz) 1319. 72893(53) 1309 + 0. 79% D J (k. Hz) 0. 121878(148) D JK (k. Hz) 1. 12900(300) d. K(k. Hz) 0. 72227(190) F J (m. Hz) 0. 1980(131) # of obs. lines 104 rms 41 k. Hz Observed frequency region: 120 - 180 GHz

Low-lying vibrationally excited states (DFT calculation) 5 -MH Hydantoin 76. 5 122. 5 137. 9 148. 0 231. 8 381. 0 241. 1 382. 5 349. 1 385. 7 441. 6 (cm-1) Several spectral lines are assigned to 5 -MH in the vibrationally excited states.

Conclusions • Pure rotational spectra of 5 -methylhydantoin (5 MH) in the ground and 2 vibrationally excited states have been successfully assigned. • Absence of spectroscopic evidence for internal rotation (A-E splitting) • Frequency catalogues are now almost ready for astronomical search of 5 -MH in the ground vibrational state below 200 GHz.

Acknowledgments JSPS KAKENHI Grants-in-Aid for Scientific Research Grant #s : 24540238, 15 K 05027, 18 K 03705