Ultrafast Energy Transfer in Orthogonal Heptamethine Cyanine–Naphthalimide Systems: A Pathway toward High-Energy Excitation

Article Article scientifique Article Ultrafast Energy Transfer in Orthogonal Heptamethine Cyanine–Naphthalimide Systems: A Pathway toward High-Energy Excitation eng 2026-05-14 author Jamjah Ali 0000-0002-0209-5942 Department of Inorganic and Analytical Chemistry, University of Geneva, Geneva CH-1205, Switzerland. 430115 Chimie minérale groupe 2 (CHAM2) author Koelbel Joseph 0009-0000-5963-9472 Department of Physical Chemistry, University of Geneva, Geneva CH-1205, Switzerland. 419516 Chimie Physique (groupe 10) (CHIF10) author Mohammadpour Pegah Chemistry Department, Sharif University of Technology, Tehran 11155-9516, Iran. author Raeesi Amir Mohammad 0009-0007-5554-4258 Chemistry Department, Sharif University of Technology, Tehran 11155-9516, Iran. author Honarvar Yeganeh 0009-0000-5219-5709 Chemistry Department, Sharif University of Technology, Tehran 11155-9516, Iran. author Nozary Homayoun Department of Inorganic and Analytical Chemistry, University of Geneva, Geneva CH-1205, Switzerland. 86105 Département de chimie minérale et analytique (CHIAM) author Jamali Sirous 0000-0002-5997-2619 Chemistry Department, Sharif University of Technology, Tehran 11155-9516, Iran. author Fernández-Terán Ricardo José 0000-0002-4665-3520 Department of Physical Chemistry, University of Geneva, Geneva CH-1205, Switzerland. 405679 Département de chimie physique (CHIFI) Ricardo José Fernandez Teran acs.jpca.6c01137 10.1021/acs.jpca.6c01137 42133939 1089-5639 https://pubs.acs.org/doi/10.1021/acs.jpca.6c01137 We report the synthesis and photophysical characterization of a family of bichromophoric systems, in which substituted naphthalimides (NMI) are covalently attached at the meso position of heptamethine cyanines (Cy7). Single crystal X-ray diffraction and DFT calculations reveal a near-perpendicular arrangement of the NMI and Cy7 moieties, resulting in minimal electronic communication. Complementary variable-temperature NMR measurements reveal potential fluctuations in the dihedral angle between the two moieties. Steady-state spectroscopy and femtosecond transient absorption measurements reveal a non-negligible excited state coupling, linked to ultrafast internal conversion/energy transfer from an NMI localized high-lying excited state to the cyanine S1 state. This process occurs on a subpicosecond time scale for all dyads, regardless of NMI substitution, leading to a large excitation-emission wavelength difference and an effective monochromophoric fluorescence behavior. Comparative studies with the NMI-pyridine precursors further highlight the role of intramolecular charge transfer in shaping the ultrafast dynamics in these systems, prior to cyanine attachment. Altogether, our results establish clear structure-property relationships for cyanine-based antenna constructs, thus providing design principles for multichromophoric systems that broaden cyanine absorption while preserving the integrity of the polymethine core. Dewey 540 Swiss National Science Foundation Ultrafast Insight into the Mechanism of Proton-Coupled Electron Transfer and its Vibrational Control 216249 CH 38 Département de chimie physique 142 40 Département de chimie minérale, analytique et appliquée 145 false 1446 Groupe Fernández-Terán 774 Groupe Piguet The journal of physical chemistry. A 4c0d7501-de1e-4f71-a9bf-b85f542cc711 Article (Accepted version) Public Manuscript_Cy7NMI_r1.pdf 1848926 application/pdf Restricted 2027-05-15 2c35a7be12c9a5319651a550f0218fafacf764ad7776d6e118d6da65f2c541e7 b3fee9b3-0731-4321-8a93-7c3681a5f064 Article (Published version) Restricted ultrafast-energy-transfer-in-orthog.pdf 2981512 application/pdf 17aa98e94d7fae4e51a83160a1034341a8f00d79c2320ef5aca173bd6cb25f1e Vignette Public TOCfigure.png 114990 image/png embargoedAccess Faculté des sciences / Section de chimie et biochimie / Département de chimie physique Faculté des sciences / Section de chimie et biochimie / Département de chimie minérale, analytique et appliquée

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Ultrafast Energy Transfer in Orthogonal Heptamethine Cyanine–Naphthalimide Systems: A Pathway toward High-Energy Excitation	The journal of physical chemistry. A			2026	9	0

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Jamjah, Ali