Multi-spectroscopic and theoretical analyses on the diphenyl ether-tert-butyl alcohol complex in the electronic ground and electronically excited state

• Published in: Physical chemistry chemical physics : PCCP 2017-07, Vol.19 (27), p.18076-18088
• Main Authors: Bernhard, Dominic, Dietrich, Fabian, Fatima, Mariyam, Perez, Cristobal, Poblotzki, Anja, Jansen, Georg, Suhm, Martin A, Schnell, Melanie, Gerhards, Markus
• Format: Article
• Language: English
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/c7cp02967e

Aromatic ethers such as diphenyl ether (DPE) represent molecules with different docking sites for alcohols leading to competing OH-O and OH-π interactions. In a multi-spectroscopic approach in combination with quantum chemical calculations the complex of DPE with tert-butyl alcohol (t-BuOH) is investigated in the electronic ground state (S ) and the electronically excited state (S ). FTIR, microwave as well as mass- and isomer-selective IR/R2PI spectra are recorded, revealing co-existing OH-O and OH-π isomers in the S state. Surprisingly, they are predicted to be of almost equal stability in contrast to the previously investigated DPE-MeOH complex, where the OH-π structure is preferred by both theory and experiment. The tert-butyl group in t-BuOH allows for a simultaneous optimization of hydrogen-bonding and dispersion interactions, which provides a sensitive meeting point between theory and experiment. In the electronically excited state of DPE-t-BuOH, vibrational spectra could be recorded separately for both isomers using UV/IR/UV spectroscopy. In the S state the same structural binding motifs are obtained as in the S state with the OH-O bond being weakened for the OH-O arrangement and the OH-π interaction being strengthened in the case of the OH-π isomer compared to the S state.