Capturing the Elusive Water Trimer from the Stepwise Growth of Water on the Surface of the Polycyclic Aromatic Hydrocarbon Acenaphthene.

Polycyclic aromatic hydrocarbons (PAHs) are key players in reaction chemistry. While it is postulated that they serve as a basis for ice grains, there has been no direct detection of PAHs in astronomical environments. We aim to investigate the hydration of PAHs to set a foundation for the future exploration of potential ice formation pathways. We report results from chirped pulse Fourier transform microwave spectroscopy and quantum-chemical calculations for the PAH acenaphthene and acenaphthene complexed with up to four water molecules. The acenaphthene-(H2O)3 complex is of particular interest as the elusive cyclic water trimer was observed. It appears in a slightly distorted configuration when compared with the pure water trimer. This is explained by hydrogen-bond net cooperativity effects. Binding energies for the complexes are presented. Our results provide insight into the onset of complex aggregation that could be occurring in extraterrestrial environments as part of ice grain formation.

[1]  Alexander G. G. M. Tielens,et al.  Interstellar Polycyclic Aromatic Hydrocarbon Molecules , 2008 .

[2]  C. Bauschlicher,et al.  THE NASA AMES PAH IR SPECTROSCOPIC DATABASE VERSION 2.00: UPDATED CONTENT, WEB SITE, AND ON(OFF)LINE TOOLS , 2014 .

[3]  Jan Cami,et al.  Detection of C60 and C70 in a Young Planetary Nebula , 2010, Science.

[4]  V. Bierbaum,et al.  PAHs and the Chemistry of the ISM , 2011, PAHs and the Universe.

[5]  Z. Kisiel.  Least-squares mass-dependence molecular structures for selected weakly bound intermolecular clusters , 2003 .

[6]  Daniel P. Tabor,et al.  Isomer-Specific Spectroscopy of Benzene-(H2O)n, n = 6,7: Benzene's Role in Reshaping Water's Three-Dimensional Networks. , 2015, The journal of physical chemistry letters.

[7]  L. Evangelisti,et al.  Internal dynamics in complexes of water with organic molecules. Details of the internal motions in tert-butylalcohol-water. , 2010, Physical chemistry chemical physics : PCCP.

[8]  J. Skinner,et al.  The water hexamer: three-body interactions, structures, energetics, and OH-stretch spectroscopy at finite temperature. , 2012, The Journal of chemical physics.

[9]  Orsay,et al.  Polycyclic aromatic hydrocarbon processing in interstellar shocks , 2009, 0910.2461.

[10]  Daniel P. Tabor,et al.  Local Mode Approach to OH Stretch Spectra of Benzene-(H2O)n Clusters, n = 2-7. , 2015, The journal of physical chemistry. A.

[11]  Olivier Berné,et al.  Formation of buckminsterfullerene (C60) in interstellar space , 2011, Proceedings of the National Academy of Sciences.

[12]  P. Theulé,et al.  Rotational Spectra of Small PAHs: Acenaphthene, Acenaphthylene, Azulene, and Fluorene , 2007 .

[13]  J. Kraitchman.  Determination of Molecular Structure from Microwave Spectroscopic Data , 1953 .

[14]  Brooks H. Pate,et al.  Structures of Cage, Prism, and Book Isomers of Water Hexamer from Broadband Rotational Spectroscopy , 2012, Science.

[15]  Roger E Bumgarner,et al.  Benzene Forms Hydrogen Bonds with Water , 1992, Science.

[16]  Berhane Temelso,et al.  Benchmark structures and binding energies of small water clusters with anharmonicity corrections. , 2011, The journal of physical chemistry. A.

[17]  J. López,et al.  Water-water and water-solute interactions in microsolvated organic complexes. , 2015, Angewandte Chemie.

[18]  J. Watson,et al.  Least-Squares Mass-Dependence Molecular Structures. , 1999, Journal of molecular spectroscopy.

[19]  R. Saykally,et al.  Measurement of quantum tunneling between chiral isomers of the cyclic water trimer. , 1992, Science.

[20]  Alexander G. G. M. Tielens,et al.  The formation of buckminsterfullerene (C$_{60}$) in interstellar space , 2011 .

[21]  F. Keutsch,et al.  The water trimer. , 2003, Chemical reviews.

[22]  Brooks H. Pate,et al.  Hydrogen bond cooperativity and the three-dimensional structures of water nonamers and decamers. , 2014, Angewandte Chemie.

[23]  H. S. Gutowsky,et al.  Rotational Spectra, Structure, and Dynamics of Arm-(H2O)n Clusters: Ar2-H2O, Ar3-H2O, Ar-(H2O)2, and Ar-(H2O)3 , 1994 .

[24]  Brooks H. Pate,et al.  Concerted hydrogen-bond breaking by quantum tunneling in the water hexamer prism , 2016, Science.

[25]  Robert Moszynski,et al.  Perturbation Theory Approach to Intermolecular Potential Energy Surfaces of van der Waals Complexes. , 1995 .

[26]  Brooks H. Pate,et al.  Broadband Fourier transform rotational spectroscopy for structure determination: The water heptamer , 2013 .

[27]  Brooks H. Pate,et al.  The rotational spectrum of epifluorohydrin measured by chirped-pulse Fourier transform microwave spectroscopy , 2006 .

[28]  Richard J. Saykally,et al.  Water clusters: Untangling the mysteries of the liquid, one molecule at a time , 2001, Proceedings of the National Academy of Sciences of the United States of America.

[29]  C. Joblin,et al.  Interstellar polycylic aromatic hydrocarbons: from space to the laboratory , 2009 .

[30]  H. S. Gutowsky,et al.  Low-J rotational spectra, internal rotation, and structures of several benzene-water dimers , 1993 .

[31]  Zbigniew Kisiel,et al.  Corannulene and its complex with water: a tiny cup of water. , 2017, Physical chemistry chemical physics : PCCP.

[32]  G. Shields,et al.  Accurate predictions of water cluster formation, (H₂O)(n=2-10). , 2010, The journal of physical chemistry. A.

[33]  Melanie Schnell,et al.  Broadband Rotational Spectroscopy for Molecular Structure and Dynamics Studies , 2012 .

[34]  Nobuyuki Akai,et al.  The effect of cooperative hydrogen bonding on the OH stretching-band shift for water clusters studied by matrix-isolation infrared spectroscopy and density functional theory. , 2005, Physical chemistry chemical physics : PCCP.

[35]  John S. Muenter,et al.  Microwave spectrum and structure of hydrogen bonded water dimer , 1974 .

[36]  A. Tielens,et al.  Interstellar polycyclic aromatic hydrocarbons: the infrared emission bands, the excitation/emission mechanism, and the astrophysical implications. , 1989, The Astrophysical journal. Supplement series.