Energy transfer pathways in pyridylporphyrin Re(I) adducts

Ghirotti, Marco; Chiorboli, Claudio; Indelli, María Teresa; Scandola, Franco; Casanova, Massimo; Iengo, Elisabetta; Alessio, Enzo

doi:10.1016/j.ica.2006.08.039

Cited by 22 publications

(35 citation statements)

References 55 publications

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“…The decrease in quantum yield of the prisms relative to free TPyP is attributed in part to the Pt heavy atom effect. Heavy atoms enhance spin-orbit coupling of a formally spin-forbidden deactivation process of the singlet state of the porphyrin (62). Although Pt is a promising metal from a structural standpoint, future designs may display improved photophysical properties by incorporating alternative metals so as to minimize spin-orbit coupling.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and photophysical studies of self-assembled multicomponent supramolecular coordination prisms bearing porphyrin faces

Shi

Sánchez‐Molina

Cao

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Multicomponent self-assembly, wherein two unique donor precursors are combined with a single metal acceptor instead of the more common two-component assembly, can be achieved by selecting Lewis-basic sites and metal nodes that select for heteroligated coordination spheres. Platinum(II) ions show a thermodynamic preference for mixed pyridyl/carboxylate coordination environments and are thus suitable for such designs. The use of three or more unique building blocks increases the structural complexity of supramolecules. Herein, we describe the synthesis and characterization of rectangular prismatic supramolecular coordination complexes (SCCs) with two faces occupied by porphyrin molecules, motivated by the search for new multichromophore complexes with promising light-harvesting properties. These prisms are obtained from the self-assembly of a 90°Pt(II) acceptor with a meso-substituted tetrapyridylporphyrin (TPyP) and dicarboxylate ligands. The generality of this self-assembly reaction is demonstrated using five dicarboxylate ligands, two based on a rigid central phenyl ring and three alkyl-spaced variants, to form a total of five free-base and five Zn-metallated porphyrin prisms. All 10 SCCs are characterized by 31 P and 1 H multinuclear NMR spectroscopy and electrospray ionization mass spectrometry, confirming the structure of each self-assembly and the stoichiometry of formation. The photophysical properties of the resulting SCCs were investigated revealing that the absorption and emission properties of the free-base and metallated porphyrin prisms preserve the spectral features associated with free TPyP. supramolecular chemistry | metallacages T he use of sunlight is ubiquitous as the input for carbonneutral, renewable energy schemes (1). Every strategy that relies on solar energy conversion, ranging from direct conversion to electricity in photovoltaics (2) to the generation of fuels via electrocatalysis (3), photoanode (4, 5), or photocathode devices (6), or photocatalysis (7) requires that photons be absorbed by a molecule or material as the first step in providing the driving force for subsequent transformation. Natural systems have evolved light-harvesting complexes, comprising multiprotein ensembles embedded with pigment molecules to enhance photon absorption for photosynthesis (8). These pigment-rich sites are arranged such that excitation of a distal chromophore will ultimately result in energy transfer to a reaction center via a series of migration and transfer processes (9). Strategies to replicate natural light-harvesting complexes necessarily demand the organization of multiple chromophores (10), a requirement that makes self-assembly and supramolecular chemistry particularly well suited for such efforts (11-13). As such, a variety of approaches have been applied toward the development of new materials that exhibit broadband absorption and efficient energy transfer (14-16). The subsequent studies of such materials span investigations of the fundamental science behind energy migration and transfer, t...

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Section: Resultsmentioning

confidence: 99%

Synthesis and photophysical studies of self-assembled multicomponent supramolecular coordination prisms bearing porphyrin faces

Shi

Sánchez‐Molina

Cao

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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“…According to ref 25, an increase in the triplet formation quantum yield is expected due to the heavy atom effect. However, a careful analysis of this reference, as well as of other similar works, 15,26 shows that the authors do not measure the intersystem crossing time. Instead, they conclude that the porphyrin intersystem crossing is enhanced because of the absences of intersystem crossing from porphyrin ring to ruthenium moieties.…”

Section: Articlementioning

confidence: 91%

Investigation of Ground- and Excited-State Photophysical Properties of 5,10,15,20-Tetra(4-pyridyl)-21H,23H-porphyrin with Ruthenium Outlying Complexes

et al. 2011

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The present work employs a set of complementary techniques to investigate the influence of outlying Ru(II) groups on the ground- and excited-state photophysical properties of free-base tetrapyridyl porphyrin (H(2)TPyP). Single pulse and pulse train Z-scan techniques used in association with laser flash photolysis, absorbance and fluorescence spectroscopy, and fluorescence decay measurements, allowed us to conclude that the presence of outlying Ru(II) groups causes significant changes on both electronic structure and vibrational properties of porphyrin. Such modifications take place mainly due to the activation of nonradiative decay channels responsible for the emission quenching, as well as by favoring some vibrational modes in the light absorption process. It is also observed that, differently from what happens when the Ru(II) is placed at the center of the macrocycle, the peripheral groups cause an increase of the intersystem crossing processes, probably due to the structural distortion of the ring that implies a worse spin-orbit coupling, responsible for the intersystem crossing mechanism.

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“…Nanosecond transient absorption experiments for a great variety of porphyrins have extensively reported the formation and dynamics of triplet state in literature [22,24,45,52,53]. The transient absorption spectrum of a free base tetrapyridyl porphyrin shows a characteristic bleach of the ground state between 400 nm and 430 nm, and a growth from 430 nm to 500 nm.…”

Section: Transient Spectroscopymentioning

confidence: 99%

“…T 1 intersystem crossing mechanism, in a similar way to when the heavy atoms are used as central substituents to the porphryin ring [30,53]. However it has been shown that ruthenium outlying groups induce distortions of the porphyrin ring hindering spin-orbit coupling [45].…”

Section: Transient Spectroscopymentioning

confidence: 99%

Investigation of the photophysical and eletrochemical properties of a free base tetrapyridyl porphyrin with meso carbon linked ruthenium(II) groups

Sampaio

Silva

Batista

et al. 2016

Journal of Photochemistry and Photobiology A: Chemistry

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Energy transfer pathways in pyridylporphyrin Re(I) adducts

Cited by 22 publications

References 55 publications

Synthesis and photophysical studies of self-assembled multicomponent supramolecular coordination prisms bearing porphyrin faces

Synthesis and photophysical studies of self-assembled multicomponent supramolecular coordination prisms bearing porphyrin faces

Investigation of Ground- and Excited-State Photophysical Properties of 5,10,15,20-Tetra(4-pyridyl)-21H,23H-porphyrin with Ruthenium Outlying Complexes

Investigation of the photophysical and eletrochemical properties of a free base tetrapyridyl porphyrin with meso carbon linked ruthenium(II) groups

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