Non-covalent close contacts in fluorinated thiophene-phenylene-thiophene conjugated units: understanding the nature and dominance of O···H versus S···F and O···F interactions towards the control of polymer conformation

Kharandiuk, T. et al. (2019) Non-covalent close contacts in fluorinated thiophene-phenylene-thiophene conjugated units: understanding the nature and dominance of O···H versus S···F and O···F interactions towards the control of polymer conformation. Chemistry of Materials, 31(17), pp. 7070-7079. (doi: 10.1021/acs.chemmater.9b01886)

Abstract

Using a simple -conjugated trimer, EDOT-phenylene-EDOT (where EDOT = 3,4-ethylenedioxythiophene), we evaluate the effect that fluorine substituents have upon changes in conformation, conjugation and oxidation potentials in -conjugated structures. These variations are assessed as a function of the fluorine atom’s propensity to feature in hydrogen and/or halogen bonding with other heteroatoms. The molecular motif was chosen because the EDOT unit presents the possibility of competing O···X or S···X non-covalent contacts (where X = H or F). Such non-bonding interactions are acknowledged to be highly influential in dictating molecular and polymer morphology and inducing changes in certain physical properties. We have studied four compounds, beginning with an unsubstituted bridging phenylene ring and then adding one, two or four fluorine units to the parent molecule. Our studies involve single crystal XRD studies, cyclic voltammetry, absorption spectroscopy and density functional theory calculations to identify the dominant non-covalent interactions and elucidate their effects on the molecules described. Experimental studies have also been carried out on the corresponding electrochemically synthesized polymers to confirm that these non-covalent interactions and their effects persist in polymers. Our findings show that hydrogen bonding and halogen bonding feature in these molecules and their corresponding polymers. ABSTRACT: Using a simple -conjugated trimer, EDOT-phenylene-EDOT (where EDOT = 3,4-ethylenedioxythiophene), we evaluate the effect that fluorine substituents have upon changes in conformation, conjugation and oxidation potentials in -conjugated structures. These variations are assessed as a function of the fluorine atom’s propensity to feature in hydrogen and/or halogen bonding with other heteroatoms. The molecular motif was chosen because the EDOT unit presents the possibility of competing O···X or S···X non-covalent contacts (where X = H or F). Such non-bonding interactions are acknowledged to be highly influential in dictating molecular and polymer morphology and inducing changes in certain physical properties. We have studied four compounds, beginning with an unsubstituted bridging phenylene ring and then adding one, two or four fluorine units to the parent molecule. Our studies involve single crystal XRD studies, cyclic voltammetry, absorption spectroscopy and density functional theory calculations to identify the dominant non-covalent interactions and elucidate their effects on the molecules described. Experimental studies have also been carried out on the corresponding electrochemically synthesized polymers to confirm that these non-covalent interactions and their effects persist in polymers. Our findings show that hydrogen bonding and halogen bonding feature in these molecules and their corresponding polymers.

• Item Type: Articles
• Additional Information: TK, RP, RN and PJS thank the European Commission (Marie Curie Action of FP7, Grant No.: PIRSES-GA-2013-612670) for financial support. The work at the University of Kentucky was supported by the National Science Foundation Designing Materials to Revolutionize and Engineer our Future (NSF DMREF) pro-gram under Award DMR-1627428. Supercomputing re-sources on the Lipscomb High Performance Computing Cluster were provided by the University of Kentucky Infor-mation Technology Department and Center for Computa-tional Sciences (CCS).
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Cameron, Dr Joseph and Skabara, Professor Peter and Findlay, Dr Neil and Hussien, Mrs Eman
• Authors: Kharandiuk, T., Hussien, E. J., Cameron, J., Petrina, R., Findlay, N. J., Naumov, R., Klooster, W. T., Coles, S. J., Ai, Q., Goodlett, S., Risko, C., and Skabara, P. J.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: Chemistry of Materials
• Publisher: American Chemical Society
• ISSN: 0897-4756
• ISSN (Online): 1520-5002
• Published Online: 27 June 2019
• Copyright Holders: Copyright © 2019 American Chemical Society
• First Published: First published in Chemistry of Materials 31(17):7070-7079
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher