Aluminium(iii) porphyrins as supramolecular building blocks

Davidson, Gregory J. E.; Tong, L.; Raithby, Paul R.; Sanders, Jeremy K. M.

doi:10.1039/b605435h

Cited by 50 publications

(51 citation statements)

References 13 publications

(6 reference statements)

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“…An isosbestic point is observed at λ =555 nm, indicating complex formation. The observed shifts in the porphyrin bands are typical of axial coordination of nitrogen ligands to AlPor 6b,h. 15 Benesi–Hildebrand16 analysis (Figure 5, inset) gives a linear plot confirming that a 1:1 complex is formed and the slope yields the binding constant K =1.1×10 3 M −1 .…”

Section: Resultsmentioning

confidence: 80%

Long‐Lived Charge Separation in Novel Axial Donor–Porphyrin–Acceptor Triads Based on Tetrathiafulvalene, Aluminum(III) Porphyrin and Naphthalenediimide

Poddutoori

Zarrabi

Moiseev

et al. 2013

Chemistry A European J

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Two self-assembled supramolecular donor-acceptor triads consisting of Al(III) porphyrin (AlPor) with axially bound naphthalenediimide (NDI) as an acceptor and tetrathiafulvalene (TTF) as a secondary donor are reported. In the triads, the NDI and TTF units are attached to Al(III) on opposite faces of the porphyrin, through covalent and coordination bonds, respectively. Fluorescence studies show that the lowest excited singlet state of the porphyrin is quenched through electron transfer to NDI and hole transfer to TTF. In dichloromethane hole transfer to TTF dominates, whereas in benzonitrile (BN) electron transfer to NDI is the main quenching pathway. In the nematic phase of the liquid crystalline solvent 4-(n-pentyl)-4'-cyanobiphenyl (5CB), a spin-polarized transient EPR spectrum that is readily assigned to the weakly coupled radical pair TTF(.+)NDI(.-) is obtained. The initial polarization pattern indicates that the charge separation occurs through the singlet channel and that singlet-triplet mixing occurs in the primary radical pair. At later time the polarization pattern inverts as a result of depopulation of the states with singlet character by recombination to the ground state. The singlet lifetime of TTF(.+)NDI(.-) is estimated to be 200-300 ns, whereas the triplet lifetime in the approximately 350 mT magnetic field of the X-band EPR spectrometer is about 10 μs. In contrast, in dichloromethane and BN the lifetime of the charge separation is <10 ns.

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Section: Resultsmentioning

confidence: 80%

Long‐Lived Charge Separation in Novel Axial Donor–Porphyrin–Acceptor Triads Based on Tetrathiafulvalene, Aluminum(III) Porphyrin and Naphthalenediimide

Poddutoori

Zarrabi

Moiseev

et al. 2013

Chemistry A European J

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“…However, they remain poorly exploited for this purpose due to their challenging synthesis and purification. 13 The Al-nanoring complex T6· c -P6·(Ar ′ CO 2 ) 6 was prepared in three steps from the corresponding zinc-porphyrin nanoring. 6b Treating this zinc nanoring with excess trifluoroacetic acid yielded the free-base porphyrin nanoring, which was then remetalated using AlMe 3 and finally isolated as T6· c -P6·(Ar ′ CO 2 ) 6 (see the Supporting Information for experimental procedures).…”

Section: Resultsmentioning

confidence: 99%

“…It is driven by the complementary metal–ligand interactions present in the two ring components: the inner 6-porphyrin nanoring has aluminum(III) metal centers, which selectively bind carboxylate ligands, whereas the outer 12-porphyrin nanoring has zinc(II) centers, which coordinate nitrogen-containing ligands such as imidazoles. 12 , 13 Time-resolved photophysical experiments show that the Russian doll complex behaves as a single emitter and that excitation is transferred outward, from the inner 6-porphyrin nanoring to the outer 12-porphyrin ring. Finally, we demonstrate that the smaller 6-porphyrin ring can be used as a template to direct the synthesis of the 12-porphyrin nanoring.…”

Section: Introductionmentioning

confidence: 99%

Self-Assembly of Russian Doll Concentric Porphyrin Nanorings

et al. 2015

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Electronic communication between concentric macrocycles with wave functions that extend around their circumferences can lead to remarkable behavior, as illustrated by multiwalled carbon nanotubes and photosynthetic chlorophyll arrays. However, it is difficult to hold one π-conjugated molecular ring inside another. Here, we show that ring-in-ring complexes, consisting of a 6-porphyrin ring locked inside a 12-porphyrin ring, can be assembled by placing different metals in the two rings (zinc and aluminum). A bridging ligand with carboxylate and imidazole binding sites forms spokes between the two rings, resulting in a highly cooperative supramolecular self-assembly process. Excitation is transferred from the inner 6-ring to the outer 12-ring of this Russian doll complex within 40 ps. These complexes lead to a form of template-directed synthesis in which one nanoring promotes formation of a larger concentric homologous ring; here, the effective template is an eight-component noncovalent assembly. Russian doll templating provides a new approach to amplifying the size of a covalent nanostructure.

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“…Although aluminium(III) porphyrins are well known for their catalytic properties and their rich photo-and electrochemistry [13][14][15], their use as molecular building blocks for the design of porphyrin arrays remains limited. The synthesis of porphyrin arrays including aluminium(III) porphyrins is mostly limited to the use of phenolates [16] and carboxylates [17] as the axial ligand. Surprisingly, there is no example of aluminium(III) porphyrins axially bonded to salicylate anion.…”

Section: Introductionmentioning

confidence: 99%

Electrochemical and Spectroscopic Characterization of Aluminium(III)-para-methyl-meso-tetraphenylporphyrin Complexes Containing Substituted Salicylates as Axial Ligands

Bajju

Deepmala

Anand

et al. 2013

International Journal of Electrochemistry

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A series of aluminium(III)-p-methyl-meso-tetraphenylporphyrin (p-CH3TPP-Al(III)) containing axially coordinated salicylate anion [p-CH3TPP-Al-X)], where X = salicylate (SA), 4-chlorosalicylate (4-CSA), 5-chlorosalicylate (5-CSA), 5-flourosalicylate (5-FSA), 4-aminosalicylate (4-ASA), 5-aminosalicylate (5-ASA), 5-nitrosalicylate (5-NSA), and 5-sulfosalicylate (5-SSA), have been synthesized and characterized by various spectroscopic techniques including ultraviolet-visible (UV-vis), infrared (IR) spectroscopy, proton nuclear magnetic resonance (1H NMR) spectroscopy,13C NMR, and elemental analysis. A detailed study of electrochemistry of all the synthesized compounds has been done to compare their oxidation and reduction mechanisms and to explain the effect of axial coordination on their redox properties.

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Aluminium(iii) porphyrins as supramolecular building blocks

Abstract: Aluminium(III) porphyrin-carboxylate complexes, including a porphyrin pentamer, have been characterised by NMR spectroscopy, MALDI spectrometry and single crystal X-ray diffraction; these complexes can also be coordinated by a sixth, nitrogenous, ligand to the aluminium(III) centre.

Cited by 50 publications

References 13 publications

Long‐Lived Charge Separation in Novel Axial Donor–Porphyrin–Acceptor Triads Based on Tetrathiafulvalene, Aluminum(III) Porphyrin and Naphthalenediimide

Long‐Lived Charge Separation in Novel Axial Donor–Porphyrin–Acceptor Triads Based on Tetrathiafulvalene, Aluminum(III) Porphyrin and Naphthalenediimide

Self-Assembly of Russian Doll Concentric Porphyrin Nanorings

Electrochemical and Spectroscopic Characterization of Aluminium(III)-para-methyl-meso-tetraphenylporphyrin Complexes Containing Substituted Salicylates as Axial Ligands

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