Electron vs Energy Transfer in Arrays Featuring Two Bodipy Chromophores Axially Bound to a Sn(IV) Porphyrin via a Phenolate or Benzoate Bridge

Abstract

In this report we describe the synthesis of multichromophore arrays consisting of two Bodipy units axially bound to a Sn(IV) porphyrin center either via a phenolate (3) or via a carboxylate (6) functionality. Absorption spectra and electrochemical studies show that the Bodipy and porphyrin chromophores interact weakly in the ground state. However, steady-state emission and excitation spectra at room temperature reveal that fluorescence from both the Bodipy and the porphyrin of 3 are strongly quenched suggesting that, in the excited state, energy and/or electron transfer might occur. Indeed, as transient absorption experiments show, selective excitation of Bodipy in 3 results in a rapid decay (τ ≈ 2 ps) of the Bodipy-based singlet excited state and a concomitant rise of a charge-separated state evolving from the porphyrin-based singlet excited state. In contrast, room-temperature emission studies on 6 show strong quenching of the Bodipy-based fluorescence leading to sensitized emission from the porphyrin moiety due to a transduction of the singlet excited state energy from Bodipy to the porphyrin. Emission experiments at 77 K in frozen toluene reveal that the room-temperature electron transfer pathway observed in 3 is suppressed. Instead, Bodipy excitation in 3 and 6 results in population of the first singlet excited state of the porphyrin chromophore. Subsequently, intersystem crossing leads to the porphyrin-based triplet excited state.

Synthesis and Characterization of Far‐Red/NIR‐Fluorescent BODIPY Dyes, Solid‐State Fluorescence, and Application as Fluorescent Tags Attached to Carbon Nano‐onions

“…[b] Measured relative to meso ‐phenol‐substituted BODIPY. Quantum yield: 0.64 in toluene 49. [c] Measured relative to zinc(II)tetra‐ tert ‐butylphthalocyanine.…”

“…Scheme2.Functionalization of hydroxy-terminated CNO-OH with BODIPY 3. i) Acetone, K 2 CO 3 . [49] [c] Measured relative to zinc(II)tetra-tert-butylphthalocyanine. Quantum yield: 0.27 in THF.…”

Benefits of using BODIPY–porphyrin dyads for developing deep-red lighting sources

“…Herein, we report on a new concept to decouple charge transport and emission in small-molecule LECs by using only one active compound mixed with an ionic electrolyte. To this end, we took advantage of our mature experience in the synthesis of BODIPYporphyrin dyads and their implementation in solar cells [16][17][18][19] to trapping process at the porphyrin, (ii) there is an almost quantitative ET process from the BODIPY to the porphyrin, (iii) there is a lack of phase separation between both components in thin films as they are linked, and (iv) porphyrins are considered as one of the best candidates for developing narrow emission deepred OLEDs. 2,[20][21][22][23][24][25][26][27] On the other hand, LECs are ideal devices to demonstrate our concept, as they are single layer devices based on a single active component, allowing to settle clear relationships between molecular design and device performance.…”

Strategic Construction of Directly Linked Porphyrin–BODIPY Hybrids

“…[1] Among them, porphyrin and boron dipyrrin (BODIPY) compounds have attracted most intensive attention in ar ange of fields such as models of photosynthetic reaction center, solar cells,a nd chemsensors. [3,4] Most of covalently linked porphyrin-BODIPY hybrids employed spacers that determined spatial arrangements and electronic coupling,h ence influencing the rates of the energy transfer. Taking advantage of these favorable attributes,c ovalently and noncovalently linked porphyrin-BODIPY hybrids have been extensively explored.…”

“…Taking advantage of these favorable attributes,c ovalently and noncovalently linked porphyrin-BODIPY hybrids have been extensively explored. [3,4] Most of covalently linked porphyrin-BODIPY hybrids employed spacers that determined spatial arrangements and electronic coupling,h ence influencing the rates of the energy transfer. On the other hand, directly linked porphyrin-BODIPY hybrids are rather rare.A sa ne legant system, Wu and co-workers reported meso-to-meso linked porphyrin-BODIPY hybrids,which were further transformed into the corresponding fused hybrids.…”