Rigid, Branched Porphyrin Antennas: Control over Cascades of Unidirectional Energy Funneling and Charge Transfer

Abstract

Porphyrin arrays consisting of three peripheral Zinc porphyrins (ZnPs) and a central free base porphyrin (HP)-all rigidly linked to each other-serve as light-harvesting antennas as well as electron donors and are flexibly coupled to an electron-accepting C to realize the unidirectional flow of (i) excited-state energy from the ZnPs at the periphery to the HP, (ii) electrons to C, and (iii) holes to HP and, subsequently, to ZnP. Dynamics following photoexcitation are elucidated by time-resolved transient absorption measurements on the femto-, pico-, nano-, and microsecond time scales and are examined by multiwavelength as well as target analyses. Hereby, full control over the charge shift between HP and ZnP to convert the (ZnP)-HP-C charge-separated state into (ZnP)-HP-C charge-separated state is enabled by the solvent polarity: It is deactivated/switched-off in apolar toluene, while in polar benzonitrile it is activated/switched-on. Activating/switching impacts the recovery of the ground state via charge recombination rates, which differ by up to 2 orders of magnitude. All charge-separated states lead to the repopulation of the ground state with dynamics that are placed in the inverted region of the Marcus parabola.

Multiple‐Porphyrin Functionalized Hexabenzocoronenes

“…In contrast, porphyrins and related macrocycles, which are found in nature in different appearances such as heme, chlorophyll, or bacteriochlorophyll, have attracted the attention from the scientific community ever since their discovery. Due to their photophysical characteristics, featuring high extinction coefficients in the visible‐light region, porphyrins have proven to be an ideal chromophore for light‐harvesting architectures . The combination of both building blocks, porphyrins and HPBs, was initiated in 2002 by the synthesis of a HPB core, surrounded by six directly meso ‐attached porphyrins .…”

“…[1][2][3][4][5] They have provent obeasuitable scaffold for catalytic applications, [6,7] the design of supramolecular architectures, [8,9] as well as ap erfectly sized template fort he preparation of nanoring [10,11] and nano-ball [12] structures.I nc ontrast, porphyrins and related macrocycles,w hich are foundi nn ature in different appearances such as heme, chlorophyll,o rb acteriochlorophyll, have attracted the attention from the scientific community ever since their discovery.D ue to their photophysical charac-teristics, featuring high extinction coefficients in the visiblelight region, porphyrins have provent ob ea ni deal chromophoref or light-harvesting architectures. [13][14][15][16][17][18][19][20][21] Thec ombination of both buildingb locks, porphyrins and HPBs, was initiated in 2002 by the synthesis of aH PB core, surrounded by six directly meso-attached porphyrins. [22] Subsequently,t he compound class of porphyrin-HPBs expanded to al ibrary of extraordinary light-harvesting arrays.…”

Ultrafast Relaxation Processes of Conjugated Polymer Nanoparticles in the Presence of Au Nanoparticles

“…[1b, 10] For efficient electron transfer process, electron acceptors such as reduced graphene oxide, C 60 ,m etal nanoparticle etc are being used. [11] Fan et al have already showedt he hyper efficient energy transferf rom conjugatedp olymers to gold nanoparticles. [12] The surfacee nergy transfer between semiconducting polymer nanoparticles and Au nanoparticles is also reported.…”

Synthesis, Electrochemical and Photochemical Studies on π‐Extended Mono‐β‐Functionalized Porphyrin Dyads

“…A number of chromophores linked porphyrin dyads have been well documented in the literature . Many chromophores such as coumarin, anthracene, carbazole, fullerene, fluorene and quinine have been covalently linked to porphyrins to study the intramolecular EET and mimic the natural photosynthetic systems . Generally, a wide variety of meso ‐porphyrin dyads were reported whereas a very few examples of porphyrin dyad where donor/acceptor moiety was attached at β ‐pyrrole position were studied .…”

“…[34][35][36][37] Generally, a wide variety of mesoporphyrin dyads were reported whereas a very few examples of porphyrin dyad where donor/acceptor moiety was attached at b-pyrrole position were studied. [38][39][40] The electronic and redox properties were much influenced when substitution occurs at b-pyrrole positions of porphyrin core relative to meso-positions. [41][42][43] The position of donor moiety in a porphyrin dyad can greatly affect the electronic coupling between the component units which results in quite different mechanism and rates.…”