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Neisser RW, Davis JP, Alfieri ME, Harkins H, Petit AS, Tabor DP, Kidwell NM. Photophysical Outcomes of Water-Solvated Heterocycles: Single-Conformation Ultraviolet and Infrared Spectroscopy of Microsolvated 2-Phenylpyrrole. J Phys Chem A 2023; 127:10540-10554. [PMID: 38085923 DOI: 10.1021/acs.jpca.3c04472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023]
Abstract
The molecular chromophores within brown carbon (BrC) aerosols absorb solar radiation at visible and near-ultraviolet wavelengths. This contributes to the overall warming of the troposphere and the photochemical aging of aerosols. In this investigation, we combine a suite of experimental and theoretical methods to reveal the conformation-specific ultraviolet and infrared spectroscopy of 2-phenylpyrrole (2PhPy)─an extended π-conjugated pyrrole derivative and a model BrC chromophore─along with its water microsolvated molecular complexes (2PhPy:nH2O, n = 1-3). Using resonant two-photon ionization and double-resonance holeburning techniques alongside MP3 (ground state) and ADC(3) (excited state) torsional potential energy surfaces and discrete variable representation simulations, we characterized the ultraviolet spectra of 2PhPy and 2PhPy:1H2O. This analysis revealed evidence for Herzberg-Teller vibronic coupling along the CH wagging and NH stretching coordinates of the aromatic rings. Conformation-specific infrared spectroscopy revealed extended hydrogen-bonding networks of the 2PhPy:nH2O complexes. Upon stepwise addition of H2O solvation, the nearest H2O acceptor forms a strong, noncovalent interaction with the pyrrole NH donor, while the second and third H2O partners interface with the phenyl and pyrrole aromatic rings through growing van der Waals π/H atom stabilization. A local-mode Hamiltonian approach was employed for comparison with the experimental spectra, thus identifying the vibrational spectral signatures to specific 2PhPy:nH2O oscillators.
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Affiliation(s)
- Ruby W Neisser
- Department of Chemistry, The College of William & Mary, Williamsburg, Virginia 23187-8795, United States
| | - John P Davis
- Department of Chemistry, The College of William & Mary, Williamsburg, Virginia 23187-8795, United States
| | - Megan E Alfieri
- Department of Chemistry, The College of William & Mary, Williamsburg, Virginia 23187-8795, United States
| | - Hayden Harkins
- Department of Chemistry and Biochemistry, California State University─Fullerton, Fullerton, California 92834-6866, United States
| | - Andrew S Petit
- Department of Chemistry and Biochemistry, California State University─Fullerton, Fullerton, California 92834-6866, United States
| | - Daniel P Tabor
- Department of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Nathanael M Kidwell
- Department of Chemistry, The College of William & Mary, Williamsburg, Virginia 23187-8795, United States
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Arildii D, Matsumoto Y, Dopfer O. Microhydration of the Pyrrole Cation (Py +) Revealed by IR Spectroscopy: Ionization-Induced Rearrangement of the Hydrogen-Bonded Network of Py +(H 2O) 2. J Phys Chem A 2023; 127:2523-2535. [PMID: 36898005 DOI: 10.1021/acs.jpca.3c00363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/12/2023]
Abstract
Microhydration of heterocyclic aromatic molecules can be an appropriate fundamental model to shed light on intermolecular interactions and functions of macromolecules and biomolecules. We characterize herein the microhydration process of the pyrrole cation (Py+) by infrared photodissociation (IRPD) spectroscopy and dispersion-corrected density functional theory calculations (B3LYP-D3/aug-cc-pVTZ). Analysis of IRPD spectra of mass-selected Py+(H2O)2 and its cold Ar-tagged cluster in the NH and OH stretch range combined with geometric parameters of intermolecular structures, binding energies, and natural atomic charge distribution provides a clear picture of the growth of the hydration shell and cooperativity effects. Py+(H2O)2 is formed by stepwise hydration of the acidic NH group of Py+ by a hydrogen-bonded (H2O)2 chain with NH···OH···OH configuration. In this linear H-bonded hydration chain, strong cooperativity, mainly arising from the positive charge, strengthens both the NH···O and OH···O H-bonds with respect to those of Py+H2O and (H2O)2, respectively. The linear chain structure of the Py+(H2O)2 cation is discussed in terms of the ionization-induced rearrangement of the hydration shell of the neutral Py(H2O)2 global minimum characterized by the so-called "σ-π bridge structure" featuring a cyclic NH···OH···OH···π H-bonded network. Emission of the π electron from Py by ionization generates a repulsive interaction between the positive π site of Py+ and the π-bonded OH hydrogen of (H2O)2, thereby breaking this OH···π hydrogen bond and driving the hydration structure toward the linear chain motif of the global minimum on the cation potential.
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Affiliation(s)
- Dashjargal Arildii
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
| | - Yoshiteru Matsumoto
- Department of Chemistry, Faculty of Science, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529, Japan
| | - Otto Dopfer
- Institut für Optik und Atomare Physik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany
- International Research Frontiers Initiative, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama 226-8503, Japan
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Gopi R, Ramanathan N, Sundararajan K. The structure of benzonitrile-water complex as unveiled by matrix isolation infrared spectroscopy: Is it linear or cyclic at low temperatures? J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2020.128636] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Chandra S, Suryaprasad B, Ramanathan N, Sundararajan K. Dominance of unique Pπ phosphorus bonding with π donors: evidence using matrix isolation infrared spectroscopy and computational methodology. Phys Chem Chem Phys 2020; 22:20771-20791. [PMID: 32909555 DOI: 10.1039/d0cp02880k] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Albeit the first account of hypervalentπ interactions has been reported with halogenπ interactions, the feasibility of their extension to other hypervalent atoms as possible Lewis acids is still open. In this work, the role of phosphorus as an acceptor from the π electron cloud (Pπ pnicogen or phosphorus bonding) in PCl3-C2H2 and PCl3-C2H4 heterodimers is explored, by combining matrix isolation infrared spectroscopy with ab initio and DFT computational methodologies. The respective potential energy surfaces of the PCl3-C2H2 and PCl3-C2H4 heterodimers reveal unique minima stabilized by a concert of reasonably strong to weak interactions, of which Pπ phosphorus bonding was energetically dominant. Heterodimers, trimers and tetramers bound primarily by this unique phosphorus bond were generated at low temperatures. The dominance of phosphorus bonding in the PCl3-C2H2 and PCl3-C2H4 heterodimers over other interactions (such as Hπ, HCl, HP, Clπ and lone pair-π interactions) was confirmed and substantiated using extended quantum theory of atoms in molecules, natural bond orbital, electrostatic potential mapping and energy decomposition analyses. The following inferences in correlation with results from non-covalent-interaction analysis offer a complete understanding of the nature of the Pπ phosphorus bonding interactions. The significance of electrostatic forces kinetically favoring the formation of phosphorus bonded heterodimers, in addition to thermodynamic stabilization, is demonstrated experimentally.
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Affiliation(s)
- Swaroop Chandra
- Homi Bhabha National Institute, Materials Chemistry & Metal Fuel Cycle Group, Indira Gandhi Center for Atomic Research, Kalpakkam - 603102, Tamil Nadu, India.
| | - B Suryaprasad
- Homi Bhabha National Institute, Materials Chemistry & Metal Fuel Cycle Group, Indira Gandhi Center for Atomic Research, Kalpakkam - 603102, Tamil Nadu, India.
| | - N Ramanathan
- Homi Bhabha National Institute, Materials Chemistry & Metal Fuel Cycle Group, Indira Gandhi Center for Atomic Research, Kalpakkam - 603102, Tamil Nadu, India.
| | - K Sundararajan
- Homi Bhabha National Institute, Materials Chemistry & Metal Fuel Cycle Group, Indira Gandhi Center for Atomic Research, Kalpakkam - 603102, Tamil Nadu, India.
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Sarkar S, Sruthi P, Ramanathan N, Sundararajan K. Experimental evidence of N–H⋯N hydrogen bonding in the heterodimers of pyrrole with nitrogen bases. J Mol Struct 2020. [DOI: 10.1016/j.molstruc.2019.127511] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Sarkar S, Ramanathan N, Sruthi PK, Sundararajan K. Conformations of diethyl ether and its interaction with pyrrole at low temperatures. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2019; 213:361-369. [PMID: 30721851 DOI: 10.1016/j.saa.2019.01.076] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 01/25/2019] [Accepted: 01/26/2019] [Indexed: 06/09/2023]
Abstract
Conformations of diethyl ether (DEE) were studied at low temperatures in N2 and Ar matrixes. Computations performed at B3LYP/aug-cc-pVDZ level of theory yielded three minima corresponding to tt, tg± and g±g± conformers of DEE. Of the three, the tt and tg± conformers of DEE were experimentally identified in N2 and Ar matrixes. Furthermore, hydrogen bonded complexes of pyrrole (py) with DEE have been investigated using Density Functional Theory (DFT) and matrix isolation infrared spectroscopy. Computations performed at B3LYP level of theory using aug-cc-pVDZ basis set on pyrrole with tt and tg± conformers of DEE gave py-DEE-tt and py-DEE-tg± complexes, both characterized by NH⋯O interaction. Experimental evidence for the formation of py-DEE-tt and py-DEE-tg± complexes was affirmed from the shifts in the NH stretching, NH bending regions of pyrrole and COC and CH stretching regions of DEE. NBO analysis was carried out to understand the charge-transfer delocalization interactions in the conformers of DEE and its hydrogen bonded complexes.
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Affiliation(s)
- Shubhra Sarkar
- Materials Chemistry and Metal Fuel Cycle Group, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute, Kalpakkam 603 102, India
| | - N Ramanathan
- Materials Chemistry and Metal Fuel Cycle Group, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute, Kalpakkam 603 102, India
| | - P K Sruthi
- Materials Chemistry and Metal Fuel Cycle Group, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute, Kalpakkam 603 102, India
| | - K Sundararajan
- Materials Chemistry and Metal Fuel Cycle Group, Indira Gandhi Centre for Atomic Research, Homi Bhabha National Institute, Kalpakkam 603 102, India.
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Sarkar S, Ramanathan N, Sundararajan K. Experimental Evidence of Synergistic Interactions in Pyrrole–Phenol Complexes at Low Temperatures under Isolated Conditions. J Phys Chem A 2018; 122:9073-9083. [DOI: 10.1021/acs.jpca.8b09076] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Shubhra Sarkar
- Materials Chemistry & Metal Fuel Cycle Group, Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu 603 102, India
| | - N. Ramanathan
- Materials Chemistry & Metal Fuel Cycle Group, Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu 603 102, India
| | - K. Sundararajan
- Materials Chemistry & Metal Fuel Cycle Group, Homi Bhabha National Institute, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamil Nadu 603 102, India
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