Linear, Non-Conjugated Cyclic and Conjugated Cyclic Paraphenylene under Pressure

Miriam Peña-Álvarez; Samuele Fanetti; Naomi Falsini; Giulia Novelli; Juan Casado; Valentín G Baonza; Mercedes Taravillo; Simon Parsons; Roberto Bini; Margherita Citroni

doi:10.3390/molecules24193496

Linear, Non-Conjugated Cyclic and Conjugated Cyclic Paraphenylene under Pressure

Molecules. 2019 Sep 26;24(19):3496. doi: 10.3390/molecules24193496.

Authors

Affiliations

¹ School of Physics and Astronomy and Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh EH9 3FD, UK. mpenaal@ed.ac.uk.
² LENS-European Laboratory for Non-Linear Spectroscopy, 50019 Sesto, Florence, Italy. fanetti@lens.unifi.it.
³ LENS-European Laboratory for Non-Linear Spectroscopy, 50019 Sesto, Florence, Italy. nao89@hotmail.it.
⁴ Centre for Science at Extreme Conditions and EastChem School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, UK. G.Novelli@ed.ac.uk.
⁵ Department of Physical Chemistry, Faculty of Science, University of Málaga, CEI Andalucía Tech, Campus de Teatinos s/n, 29071 Málaga, Spain. casado@uma.es.
⁶ MALTA-Consolider Team, Department of Physical Chemistry I, Chemistry Faculty, University Complutense of Madrid, 28040 Madrid, Spain. vgbaonza@quim.ucm.es.
⁷ Instituto de Geociencias IGEO (CSIC-UCM), 28040 Madrid, Spain. vgbaonza@quim.ucm.es.
⁸ MALTA-Consolider Team, Department of Physical Chemistry I, Chemistry Faculty, University Complutense of Madrid, 28040 Madrid, Spain. mtaravil@quim.ucm.es.
⁹ Centre for Science at Extreme Conditions and EastChem School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, UK. Simon.Parsons@ed.ac.uk.
¹⁰ LENS-European Laboratory for Non-Linear Spectroscopy, 50019 Sesto, Florence, Italy. roberto.bini@unifi.it.
¹¹ LENS-European Laboratory for Non-Linear Spectroscopy, 50019 Sesto, Florence, Italy. margherita.citroni@nature.com.

Abstract

The n-paraphenylene family comprises chains of phenylene units linked together by C-C bonds that are between single- and double-bonded, and where n corresponds to the number of phenylene units. In this work, we compare the response of the optical properties of different phenylene arrangements. We study linear chains (LPP), cyclic systems (CPPs), and non-conjugated cyclic systems with two hydrogenated phenylenes (H₄[n]CPP). Particularly, the systems of interest in this work are [6]LPP, [12]- and [6]CPP and H₄[6]CPP. This work combines Raman and infrared spectroscopies with absorption and fluorescence (one- and two-photon excitations) measured as a function of pressure up to maximum of about 25 GPa. Unprecedented crystallographic pressure-dependent results are shown on H₄[n]CPP, revealing intramolecular π-π interactions upon compression. These intramolecular interactions justify the H₄[n]CPP singular optical properties with increasing fluorescence lifetime as a function of pressure.

Keywords: absorption; fluorescence; linear and cyclic paraphenylene; pressure; vibrational spectroscopy.

MeSH terms

Benzene Derivatives / chemistry*
Cyclization
Models, Chemical*
Molecular Structure
Pressure*
Spectroscopy, Fourier Transform Infrared
Spectrum Analysis, Raman

Substances

Benzene Derivatives

Grants and funding

LENS002098 and LENS002275/European Laboratory for Non-Linear Spectroscopy