Transient Raman Snapshots of the Twisted Intramolecular Charge Transfer State 
in a Stilbazolium Dye

Karmakar, S.; Ambastha, A.; Jha, A.; Dharmadhikari, A.; Dharmadhikari, J.; Venkatramani, R.; Dasgupta, J.

doi:10.1021/acs.jpclett.0c01124

Item

ITEM ACTIONSEXPORT

Add to Basket

Local TagsRelease HistoryDetailsSummary

Released

Journal Article

Transient Raman Snapshots of the Twisted Intramolecular Charge Transfer State in a Stilbazolium Dye

MPS-Authors

/persons/resource/persons202750

Jha, A.
Department of Chemical Sciences, TataInstitute of Fundamental Research;
Miller Group, Atomically Resolved Dynamics Department, Max Planck Institute for the Structure and Dynamics of Matter, Max Planck Society;

External Resource

https://dx.doi.org/10.1021/acs.jpclett.0c01124
(Publisher version)

Fulltext (restricted access)

There are currently no full texts shared for your IP range.

Fulltext (public)

There are no public fulltexts stored in PuRe

Supplementary Material (public)

jz0c01124_si_001.pdf
(Supplementary material), 5MB

Citation

Karmakar, S., Ambastha, A., Jha, A., Dharmadhikari, A., Dharmadhikari, J., Venkatramani, R., et al. (2020). Transient Raman Snapshots of the Twisted Intramolecular Charge Transfer State in a Stilbazolium Dye. The Journal of Physical Chemistry Letters, 11(12), 4842-4848. doi:10.1021/acs.jpclett.0c01124.

Cite as: https://hdl.handle.net/21.11116/0000-0006-C6BC-7

Abstract

Optically triggered twisted intramolecular charge transfer (TICT) states in donor–acceptor chromophores form the molecular basis for designing bioimaging probes that sense polarity, microviscosity, and pH in vivo. However, a lack of predictive understanding of the “twist” localization precludes a rational design of TICT-based dyes. Here, using femtosecond stimulated Raman spectroscopy, we reveal a distinct Raman signature of the TICT state for a stilbazolium-class mitochondrial staining dye. Resonance-selective probing of 4-N,N-diethylamino-4″-N′-methyl-stilbazolium tosylate (DEST) tracks the excited-state structure of the dye as it relaxes to a TICT state on a picosecond time scale. The appearance of a remarkably blue-shifted C=C stretching mode at 1650 cm^–1 in the TICT state is attributed to the “twist” of a single bond adjacent to the ethylenic π-bridge in the DEST backbone based on detailed electronic structure calculations and vibrational mode analysis. Our work demonstrates that the π-bridge, connecting the donor and acceptor moieties, influences the spatial location of the “twist” and offers a new perspective for designing organelle-specific probes through cogent tuning of backbone dynamics.