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Title: Substituent effects that control conjugated oligomer conformation through non-covalent interactions

Although understanding the conformations and arrangements of conjugated materials as solids is key to their prospective applications, predictive power over these structural factors remains elusive. In this work, substituent effects tune non-covalent interactions between side-chain fluorinated benzyl esters and main-chain terminal arenes, in turn controlling the conformations and interchromophore aggregation of three-ring phenylene-ethynylenes (PEs). Cofacial fluoroarene–arene (ArF–ArH) interactions cause twisting in the PE backbone, interrupting intramolecular conjugation as well as blocking chromophore aggregation, both of which prevent the typically observed bathochromic shift observed upon transitioning PEs from solution to solid. This work highlights two structural factors that determine whether the ArF–ArH interactions, and the resulting twisted, unaggregated chromophores, occur in these solids: (i) the electron-releasing characteristic of substituents on ArH, with more electron-releasing character favoring ArF–ArH interactions, and (ii) the fluorination pattern of the ArF ring, with 2,3,4,5,6-pentafluorophenyl favoring ArF–ArH interactions over 2,4,6-trifluorophenyl. Furthermore, these trends indicate that considerations of electrostatic complementarity, whether through a polar-π or substituent–substituent mechanism, can serve as an effective design principle in controlling the interaction strengths, and therefore the optoelectronic properties, of these molecules as solids.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ; ORCiD logo [1]
  1. Tufts Univ., Medford, MA (United States)
  2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Publication Date:
Grant/Contract Number:
SC0016423
Type:
Published Article
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 139; Journal Issue: 14; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Research Org:
Tufts Univ., Medford, MA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1349315
Alternate Identifier(s):
OSTI ID: 1351893

Sharber, Seth A., Baral, Rom Nath, Frausto, Fanny, Haas, Terry E., Müller, Peter, and Thomas, III, Samuel W.. Substituent effects that control conjugated oligomer conformation through non-covalent interactions. United States: N. p., Web. doi:10.1021/jacs.7b00878.
Sharber, Seth A., Baral, Rom Nath, Frausto, Fanny, Haas, Terry E., Müller, Peter, & Thomas, III, Samuel W.. Substituent effects that control conjugated oligomer conformation through non-covalent interactions. United States. doi:10.1021/jacs.7b00878.
Sharber, Seth A., Baral, Rom Nath, Frausto, Fanny, Haas, Terry E., Müller, Peter, and Thomas, III, Samuel W.. 2017. "Substituent effects that control conjugated oligomer conformation through non-covalent interactions". United States. doi:10.1021/jacs.7b00878.
@article{osti_1349315,
title = {Substituent effects that control conjugated oligomer conformation through non-covalent interactions},
author = {Sharber, Seth A. and Baral, Rom Nath and Frausto, Fanny and Haas, Terry E. and Müller, Peter and Thomas, III, Samuel W.},
abstractNote = {Although understanding the conformations and arrangements of conjugated materials as solids is key to their prospective applications, predictive power over these structural factors remains elusive. In this work, substituent effects tune non-covalent interactions between side-chain fluorinated benzyl esters and main-chain terminal arenes, in turn controlling the conformations and interchromophore aggregation of three-ring phenylene-ethynylenes (PEs). Cofacial fluoroarene–arene (ArF–ArH) interactions cause twisting in the PE backbone, interrupting intramolecular conjugation as well as blocking chromophore aggregation, both of which prevent the typically observed bathochromic shift observed upon transitioning PEs from solution to solid. This work highlights two structural factors that determine whether the ArF–ArH interactions, and the resulting twisted, unaggregated chromophores, occur in these solids: (i) the electron-releasing characteristic of substituents on ArH, with more electron-releasing character favoring ArF–ArH interactions, and (ii) the fluorination pattern of the ArF ring, with 2,3,4,5,6-pentafluorophenyl favoring ArF–ArH interactions over 2,4,6-trifluorophenyl. Furthermore, these trends indicate that considerations of electrostatic complementarity, whether through a polar-π or substituent–substituent mechanism, can serve as an effective design principle in controlling the interaction strengths, and therefore the optoelectronic properties, of these molecules as solids.},
doi = {10.1021/jacs.7b00878},
journal = {Journal of the American Chemical Society},
number = 14,
volume = 139,
place = {United States},
year = {2017},
month = {3}
}