Pathway Complexity in the Stacking of Imine-Linked Macrocycles Related to Two-Dimensional Covalent Organic Frameworks

Shiwei Wang; Anton D. Chavez; Simil Thomas; Hong Li; Nathan C. Flanders; Chao Sun; Michael J. Strauss; Lin X. Chen; Albert J. Markvoort; Jean Luc Bredas; William R. Dichtel

doi:10.1021/acs.chemmater.9b03088

Pathway Complexity in the Stacking of Imine-Linked Macrocycles Related to Two-Dimensional Covalent Organic Frameworks

Shiwei Wang, Anton D. Chavez, Simil Thomas, Hong Li, Nathan C. Flanders, Chao Sun, Michael J. Strauss, Lin X. Chen, Albert J. Markvoort, Jean Luc Bredas, William R. Dichtel^*

^*Corresponding author for this work

Department of Molecular Biology and Genetics - Neurobiology

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

Abstract

Interlayer interactions play an important role in the formation of two-dimensional covalent organic frameworks (2D COFs), yet the effects of monomer structure on COF formation, crystallinity, and susceptibility to exfoliation are not well understood. Here we probe these effects by studying the stacking behavior of imine-linked macrocycles that represent discrete models of 2D COFs. Specifically, macrocycles based on terephthaldehyde (PDA) or 2,5-dimethoxyterephthaldehyde (DMPDA) stack upon cooling molecularly dissolved solutions. Both macrocycles assemble cooperatively with similar ΔH_e values of -97 kJ/mol and -101 kJ/mol, respectively, although the DMPDA macrocycle assembly process showed a more straightforward temperature dependence. Density functional theory calculations of the stacking of PDA macrocycles suggested two stable configurations that were close in energy. Circular dichroism spectroscopy performed on macrocycles bearing chiral side chains revealed a helix reversion process for the PDA macrocycles that was not observed for the DMPDA macrocycles. Given the structural similarity of these monomers, these findings demonstrate that the stacking processes associated with nanotubes derived from these macrocycles, as well as for the corresponding COFs, are complex and susceptible to kinetic traps, casting doubt on the relevance of thermodynamic arguments for improving materials quality. Rather, a deeper understanding of the mechanism of supramolecular polymerization and its interplay with polymerization and error correction during COF synthesis is needed for improved control of the crystallinity and morphology of these emerging materials.

Original language	English
Journal	Chemistry of Materials
Volume	31
Issue	17
Pages (from-to)	7104-7111
Number of pages	8
ISSN	0897-4756
DOIs	https://doi.org/10.1021/acs.chemmater.9b03088
Publication status	Published - 10 Sept 2019

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10.1021/acs.chemmater.9b03088

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@article{6789651b94b245bf800bd12c87c1c4d0,

title = "Pathway Complexity in the Stacking of Imine-Linked Macrocycles Related to Two-Dimensional Covalent Organic Frameworks",

abstract = "Interlayer interactions play an important role in the formation of two-dimensional covalent organic frameworks (2D COFs), yet the effects of monomer structure on COF formation, crystallinity, and susceptibility to exfoliation are not well understood. Here we probe these effects by studying the stacking behavior of imine-linked macrocycles that represent discrete models of 2D COFs. Specifically, macrocycles based on terephthaldehyde (PDA) or 2,5-dimethoxyterephthaldehyde (DMPDA) stack upon cooling molecularly dissolved solutions. Both macrocycles assemble cooperatively with similar ΔHe values of -97 kJ/mol and -101 kJ/mol, respectively, although the DMPDA macrocycle assembly process showed a more straightforward temperature dependence. Density functional theory calculations of the stacking of PDA macrocycles suggested two stable configurations that were close in energy. Circular dichroism spectroscopy performed on macrocycles bearing chiral side chains revealed a helix reversion process for the PDA macrocycles that was not observed for the DMPDA macrocycles. Given the structural similarity of these monomers, these findings demonstrate that the stacking processes associated with nanotubes derived from these macrocycles, as well as for the corresponding COFs, are complex and susceptible to kinetic traps, casting doubt on the relevance of thermodynamic arguments for improving materials quality. Rather, a deeper understanding of the mechanism of supramolecular polymerization and its interplay with polymerization and error correction during COF synthesis is needed for improved control of the crystallinity and morphology of these emerging materials.",

author = "Shiwei Wang and Chavez, {Anton D.} and Simil Thomas and Hong Li and Flanders, {Nathan C.} and Chao Sun and Strauss, {Michael J.} and Chen, {Lin X.} and Markvoort, {Albert J.} and Bredas, {Jean Luc} and Dichtel, {William R.}",

note = "Funding Information: This work was funded by the Army Research Office through the Multidisciplinary University Research Initiative (MURI, W911NF-15-1-0447, to W.R.D. and J.-L.B.). A.D.C. was supported through a National Defense Science and Engineering Graduate Fellowship (NDSEG). S.W. was supported partially by the Northwestern University Summer Undergraduate Research Grant and Weinberg College Summer Undergraduate Research Grant. C.S. was partially supported by the Cornell Center for Materials Research with funding from the NSF MRSEC program (DMR-1719875). This work made use of the Integrated Molecular Structure Education and Research Center (IMSERC) at Northwestern University, which has received support from the National Science Foundation (NSF; (CHE 1048773), the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF NNCI 1542205), the State of Illinois, and the International Institute for Nanotechnology (IIN)). This work was supported in part by a grant of computer time from the DOD High Performance Computing Modernization Program. Publisher Copyright: Copyright {\textcopyright} 2019 American Chemical Society.",

year = "2019",

month = sep,

day = "10",

doi = "10.1021/acs.chemmater.9b03088",

language = "English",

volume = "31",

pages = "7104--7111",

journal = "Chemistry of Materials",

issn = "0897-4756",

publisher = "AMER CHEMICAL SOC",

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}

Pathway Complexity in the Stacking of Imine-Linked Macrocycles Related to Two-Dimensional Covalent Organic Frameworks. / Wang, Shiwei; Chavez, Anton D.; Thomas, Simil et al.
In: Chemistry of Materials, Vol. 31, No. 17, 10.09.2019, p. 7104-7111.

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

TY - JOUR

T1 - Pathway Complexity in the Stacking of Imine-Linked Macrocycles Related to Two-Dimensional Covalent Organic Frameworks

AU - Wang, Shiwei

AU - Chavez, Anton D.

AU - Thomas, Simil

AU - Li, Hong

AU - Flanders, Nathan C.

AU - Sun, Chao

AU - Strauss, Michael J.

AU - Chen, Lin X.

AU - Markvoort, Albert J.

AU - Bredas, Jean Luc

AU - Dichtel, William R.

N1 - Funding Information: This work was funded by the Army Research Office through the Multidisciplinary University Research Initiative (MURI, W911NF-15-1-0447, to W.R.D. and J.-L.B.). A.D.C. was supported through a National Defense Science and Engineering Graduate Fellowship (NDSEG). S.W. was supported partially by the Northwestern University Summer Undergraduate Research Grant and Weinberg College Summer Undergraduate Research Grant. C.S. was partially supported by the Cornell Center for Materials Research with funding from the NSF MRSEC program (DMR-1719875). This work made use of the Integrated Molecular Structure Education and Research Center (IMSERC) at Northwestern University, which has received support from the National Science Foundation (NSF; (CHE 1048773), the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF NNCI 1542205), the State of Illinois, and the International Institute for Nanotechnology (IIN)). This work was supported in part by a grant of computer time from the DOD High Performance Computing Modernization Program. Publisher Copyright: Copyright © 2019 American Chemical Society.

PY - 2019/9/10

Y1 - 2019/9/10

N2 - Interlayer interactions play an important role in the formation of two-dimensional covalent organic frameworks (2D COFs), yet the effects of monomer structure on COF formation, crystallinity, and susceptibility to exfoliation are not well understood. Here we probe these effects by studying the stacking behavior of imine-linked macrocycles that represent discrete models of 2D COFs. Specifically, macrocycles based on terephthaldehyde (PDA) or 2,5-dimethoxyterephthaldehyde (DMPDA) stack upon cooling molecularly dissolved solutions. Both macrocycles assemble cooperatively with similar ΔHe values of -97 kJ/mol and -101 kJ/mol, respectively, although the DMPDA macrocycle assembly process showed a more straightforward temperature dependence. Density functional theory calculations of the stacking of PDA macrocycles suggested two stable configurations that were close in energy. Circular dichroism spectroscopy performed on macrocycles bearing chiral side chains revealed a helix reversion process for the PDA macrocycles that was not observed for the DMPDA macrocycles. Given the structural similarity of these monomers, these findings demonstrate that the stacking processes associated with nanotubes derived from these macrocycles, as well as for the corresponding COFs, are complex and susceptible to kinetic traps, casting doubt on the relevance of thermodynamic arguments for improving materials quality. Rather, a deeper understanding of the mechanism of supramolecular polymerization and its interplay with polymerization and error correction during COF synthesis is needed for improved control of the crystallinity and morphology of these emerging materials.

AB - Interlayer interactions play an important role in the formation of two-dimensional covalent organic frameworks (2D COFs), yet the effects of monomer structure on COF formation, crystallinity, and susceptibility to exfoliation are not well understood. Here we probe these effects by studying the stacking behavior of imine-linked macrocycles that represent discrete models of 2D COFs. Specifically, macrocycles based on terephthaldehyde (PDA) or 2,5-dimethoxyterephthaldehyde (DMPDA) stack upon cooling molecularly dissolved solutions. Both macrocycles assemble cooperatively with similar ΔHe values of -97 kJ/mol and -101 kJ/mol, respectively, although the DMPDA macrocycle assembly process showed a more straightforward temperature dependence. Density functional theory calculations of the stacking of PDA macrocycles suggested two stable configurations that were close in energy. Circular dichroism spectroscopy performed on macrocycles bearing chiral side chains revealed a helix reversion process for the PDA macrocycles that was not observed for the DMPDA macrocycles. Given the structural similarity of these monomers, these findings demonstrate that the stacking processes associated with nanotubes derived from these macrocycles, as well as for the corresponding COFs, are complex and susceptible to kinetic traps, casting doubt on the relevance of thermodynamic arguments for improving materials quality. Rather, a deeper understanding of the mechanism of supramolecular polymerization and its interplay with polymerization and error correction during COF synthesis is needed for improved control of the crystallinity and morphology of these emerging materials.

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U2 - 10.1021/acs.chemmater.9b03088

DO - 10.1021/acs.chemmater.9b03088

M3 - Journal article

AN - SCOPUS:85072347908

SN - 0897-4756

VL - 31

SP - 7104

EP - 7111

JO - Chemistry of Materials

JF - Chemistry of Materials

IS - 17

ER -

Pathway Complexity in the Stacking of Imine-Linked Macrocycles Related to Two-Dimensional Covalent Organic Frameworks

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