Initial excited-state dynamics of an N -alkylated indanylidene-pyrroline (NAIP) rhodopsin analog

Igor Schapiro, Stefania Fusi, Massimo Olivucci*, Tadeusz Andruniów, Swaroop Sasidharanpillai, Glen R. Loppnow

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


N-Alkylated indanylidene-pyrroline-based molecular switches mimic different aspects of the light-induced retinal chromophore isomerization in rhodopsin: the vertebrate dim-light visual pigment. In particular, they display a similar ultrashort excited-state lifetime, subpicosecond photoproduct appearance time, and photoproduct vibrational coherence. To better understand the early light-induced dynamics of such systems, we measured and modeled the resonance Raman spectra of the Z-isomer of the N-methyl-4-(5′-methoxy-2′,2′-dimethyl-indan-1′-ylidene)-5-methyl-2,3-dihydro-2H-pyrrolium (NAIP) switch in methanol solution. It is shown that the data, complemented with a <70 fs excited-state trajectory computation, demonstrate initial excited-state structural dynamics dominated by double-bond expansion and single-bond contraction stretches. This mode subsequently couples with the five-membered ring inversion and double-bond torsion. These results are discussed in the context of the mechanism of the excited-state photoisomerization of NAIP switches in solution and the 11-cis retinal in rhodopsin.

Original languageAmerican English
Pages (from-to)12243-12250
Number of pages8
JournalJournal of Physical Chemistry B
Issue number42
StatePublished - 23 Oct 2014
Externally publishedYes

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Publisher Copyright:
© 2014 American Chemical Society.


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