A highly efficient heptamethine cyanine antenna for photosynthetic Reaction Center: From chemical design to ultrafast energy transfer investigation of the hybrid system

About the origin of the large Stokes shift in aminoalkyl substituted heptamethine cyanine dyes

“…These molecules have been exploited as fluorescent probes for bioimaging 21,22 and in artificial light harvesting antennas for solar energy conversion. [23][24][25] The mechanism at the basis of the spectroscopic effects observed upon substitution of the chlorine atom with an aminoalkyl group has not been fully addressed in the literature. Different research groups proposed an interplay between localized excitation and intermolecular charge transfer, but clear experimental evidence for this interplay is missing.…”

“…Different research groups proposed an interplay between localized excitation and intermolecular charge transfer, but clear experimental evidence for this interplay is missing. 13,23 The ion-pairing effect was also invoked for heptamethine cyanines showing different behaviours according to the counterion and/or the polarity of the solvent. 19,26 The nitrogen group in the central core definitely affects the ground-state electronic configuration, favouring the presence of the charge on the central position.…”

“…HCy2 has been selected and synthesized in the frame of studies on biohybrid systems for solar energy conversion based on the covalent bioconjugation of organic light harvesting antennas to photoenzymes. [23][24][25] The specific octyl chain of HCy2 was chosen as a suitable spacer between the chromophore and the protein, in order to prevent the sterical hindrance of HCy2 on the photoenzyme surface, thus preserving the enzymatic photoactivity. 29,30 A combined experimental and theoretical work sheds light on the origin of this large Stokes shift: the nitrogen atom linked to the cyclohexenyl ring strongly affects the conjugation of the polymethine chain, leading to a broken-symmetry ground state.…”

Nanostructured interfaces between photosynthetic bacterial Reaction Center and Silicon electrodes

“…[17] RC-organic biohybrid systems of poly-conjugated antennas directly bonded to the RC have been proposed for increasing the light harvesting capability of RC. [18][19][20] It has been also demonstrated that RC embedded in soft structures, like lipid vesicles, [21] liposomes [22] or polymersomes, can maintain its activity without being denaturated. [23] Interfaces between photosynthetic RC and inorganic electrode surface of optoelectronic films, which are commonly made of inorganic materials devices, still represent an issue.…”

Incorporating a molecular antenna in diatom microalgae cells enhances photosynthesis

“…In vivo incorporation of tailored organic dyes into microalgae by simply adding them as photoactive nutrients into cells culture can, in principle, constitute an alternative photosynthesis-enhancing approach in living algal cells, promoting light harvesting without the need for genetic modification [29][30][31][32] . In last years, organic dyes were used to demonstrate the possibility to enhance photosynthesis in green microalgae such as Chlorella sorokiniuna 33 , Dunaliella salina 34 and Nannochloropsis gaditana 35 : in particular, solutions of spectral shifting dyes were located in external cavities surrounding the microalgal photo-bioreactors, thus demonstrating that proximity of dyes solution kept separated from the algal culture can ensure transfer of the energy harvested by the dyes to algal cells without altering cells viability.…”