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Mechanical Force Enables an Anomalous Dual Ring-Opening Reaction of Naphthodipyran

McFadden, Molly E. and Osler, Skylar K. and Sun, Yan and Robb, Maxwell J. (2022) Mechanical Force Enables an Anomalous Dual Ring-Opening Reaction of Naphthodipyran. Journal of the American Chemical Society, 144 (49). pp. 22391-22396. ISSN 0002-7863. doi:10.1021/jacs.2c08817.

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Multimodal mechanophores that exhibit complex mechanochromic behavior beyond the typical binary response are capable of distinguishing between multiple stress states through discrete changes in color. Naphthodipyran photoswitches contain two pyran rings fused to a central naphthalene core and represent a potentially promising framework for multimodal reactivity. However, the concurrent ring opening of both pyran moieties has previously proven inaccessible via photochemical activation. Here, we demonstrate that mechanical force supplied to naphthodipyran through covalently linked polymer chains generates the elusive dual ring-opened dimerocyanine product with unique near-infrared absorption properties. Trapping with boron trifluoride renders the merocyanine dyes thermally persistent and reveals apparent sequential ring-opening behavior that departs from the reactivity of previously studied mechanophores under the high strain rates imposed by ultrasound-induced solvodynamic chain extension.

Item Type:Article
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URLURL TypeDescription ItemDiscussion Paper
McFadden, Molly E.0000-0003-3174-6385
Osler, Skylar K.0000-0003-1021-7011
Sun, Yan0000-0002-3882-131X
Robb, Maxwell J.0000-0002-0528-9857
Additional Information:Financial support from Caltech and an NSF CAREER award (CHE-2145791) is gratefully acknowledged. M.E.M. was supported by an NSF Graduate Research Fellowship (DGE-1745301) and a Barbara J. Burger Fellowship. S.K.O. was supported by an Institute Fellowship from Caltech. We thank Dr. Scott Virgil for helpful discussions and the Center for Catalysis and Chemical Synthesis of the Beckman institute at Caltech for access to equipment. We thank Dr. David VanderVelde for helpful discussions and technical assistance with NMR spectroscopy and the Fu laboratory at Caltech for use of their mass spectrometer. M.J.R. is an Alfred P. Sloan Research Fellow and a Camille Dreyfus Teacher-Scholar.
Funding AgencyGrant Number
NSF Graduate Research FellowshipDGE-1745301
Barbara J. Burger FellowshipUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Camille and Henry Dreyfus FoundationUNSPECIFIED
Issue or Number:49
Record Number:CaltechAUTHORS:20221219-418113000.37
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:118509
Deposited By: Research Services Depository
Deposited On:24 Jan 2023 03:12
Last Modified:24 Mar 2023 17:51

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