Comparative Synthetic Strategies for the Generation of 5,10‐ and 5,15‐Substituted <i>Push‐Pull</i> Porphyrins

Meindl, Alina; Plunkett, Shane; Ryan, Aoife A.; Flanagan, Keith J.; Callaghan, Susan; Senge, Ma­thias O.

doi:10.1002/ejoc.201700093

Cited by 16 publications

(11 citation statements)

References 94 publications

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“…The present work has identified a new motif for suppressing interactions of porphyrins in the solid state. A singlecrystal X-ray analysis of a free-base porphyrin lacking the two Br atoms has octyl groups [5,15-bis(2,6-dioctyloxyphenyl)porphyrin] in quite open conformations (Meindl et al, 2017) without the alkyl-wrapping phenomenon reported here. As such, a number of questions arise about generality, including in the absence of the 5,15-Br atoms or with other substituents in lieu thereof (e.g.…”

Section: Resultsmentioning

confidence: 83%

“…Such close-ended or 'strapped' porphyrins (Ikeda et al, 2006) have shielded faces but often present cumbersome syntheses. On the other hand, several porphyrins with open-chain alkyl groups, including at the o-positions of meso-aryl groups, exhibit alkyl groups that are generally aligned upward or away from the porphyrin plane (Nikiforov et al, 2008;Choi et al, 2013;Meindl et al, 2017). Such structures provide facial encumbrance, often extensively so, which may suffice for many applications where increased organic solubility alone is sought, but lack facial encumbrance in concert with tight packing as may be required for selected other pursuits.…”

Section: Introductionmentioning

confidence: 99%

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Fourfold alkyl wrapping of a copper(II) porphyrin thwarts macrocycle π–π stacking in a compact supramolecular package

et al. 2020

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Porphyrins are valuable constituents in optoelectronic, catalytic, and other applications, yet control of intermolecular π–π stacking is invariably essential to attain the desired properties. Superstructures built onto the porphyrin, often via meso-aryl groups, can afford facial encumbrance that suppresses π–π stacking, although some molecular designs have provided insufficient facial coverage and many have entailed cumbersome syntheses. In this study, a copper(II) porphyrin bearing four meso substituents, namely, {10,20-bis[2,6-bis(octyloxy)phenyl]-5,15-dibromoporphinato}copper(II), [Cu(C64H82Br2N4O4)], was prepared by metalation of the corresponding free-base porphyrin and was characterized by single-crystal X-ray diffraction. The crystal structure reveals a dihedral angle of 111.1 (2)° for the plane of the meso-aryl group relative to the plane of the porphyrin, with both aryl groups tilted in the same direction. Each of the four octyloxy groups exhibits a gauche conformation for the –OCH2CH2– unit but is extended with four or five anti (–CH2CH2–/H) conformations thereafter, causing each octyl group to span the dimension of the macrocycle. In a global frame of reference where the two Br atoms define the north/south poles and the two aryl groups are at antipodes on the equator, two octyl groups of one aryl unit project over the northern hemisphere (covering pyrroles A and B), whereas those of the other aryl unit project over the southern hemisphere (covering pyrroles C and D). Together, the four octyl groups ensheath the two faces of the porphyrin in a self-wrapped assembly. The closest approach of the Cu atom to an octyl methylene C atom (position 6) is 3.5817 (18) Å, the mean separations of neighboring porphyrin planes are 8.059 (4) and 4.693 (8) Å along the a and c axes, respectively, and the center-to-center distances between the Cu atoms of neighboring porphyrins are 10.2725 (4), 12.2540 (6), and 12.7472 (6) Å along the a, b, and c axes, respectively. The Hirshfeld surface analysis and two-dimensional (2D) fingerprint plots provide information concerning contact interactions in the supramolecular assembly of the solid crystal.

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Section: Resultsmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Fourfold alkyl wrapping of a copper(II) porphyrin thwarts macrocycle π–π stacking in a compact supramolecular package

et al. 2020

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“…The last compound in this series contains a 3,5-di-tertbutylphenyl in the 15,20-positions of the porphyrin ring (compound 19) [36]. This structure is a step up in steric bulk compared to compounds 16-18.…”

Section: 10-di-halo-substituted Porphyrinsmentioning

confidence: 99%

“…Details on the refinement of NESHUO (2) [27], UDERUR (3) [22], NOGWEN (12) [23], HUMWES (13A) [24], HUMWAO ( 14) [24], LASMOK (15) [33], RAKGAN (16) [34], ZOXQUA (17) [35], ZOXCAS (18) [35], BASDOR (19) [36], YISZAD(20) [39], QUGMEM (21) [38], QUGMIQ ( 22) [38], and MORBEC (23) [37] were previously reported.…”

Section: Previous Structuresmentioning

confidence: 99%

Structural effects of meso-halogenation on porphyrins

Flanagan

Dominguez

Melissari

et al. 2021

Beilstein J. Org. Chem.

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The use of halogens in the crystal engineering of supramolecular porphyrin assemblies has been a topic of strong interest over the past decades. With this in mind we have characterized a series of direct meso-halogenated porphyrins using single crystal X-ray crystallography. This is accompanied by a detailed conformational analysis of all deposited meso-halogenated porphyrins in the CSD. In this study we have used the Hirshfeld fingerprint plots together with normal-coordinate structural decomposition and determined crystal structures to elucidate the conformation, present intermolecular interactions, and compare respective contacts within the crystalline architectures. Additionally, we have used density functional theory calculations to determine the structure of several halogenated porphyrins. This contrasts conformational analysis with existing X-ray structures and gives a method to characterize samples that are difficult to crystallize. By using the methods outlined above we were able to deduce the impact a meso halogen has on a porphyrin, for example, meso-halogenation is dependent on the type of alternate substituents present when forming supramolecular assemblies. Furthermore, we have designed a method to predict the conformation of halogenated porphyrins, without need of crystallization, using DFT calculations with a high degree of accuracy.

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“…The porphyrins selected for this study were [5-(4- porphyrins with different donor units, which have a dipole running along the meso-meso axis. 31 The design of these porphyrins is based on state-of-the-art push-pull porphyrins for dye-sensitized solar cells. 29 The 32 Briefly, a white-light continuum probe pulse was generated in a 2-mmthick sapphire plate utilizing a small fraction of the fundamental output of a Ti:sapphire femtosecond regenerative amplifier, which was operating at 800 nm with 35 fs pulses, and a repetition rate of 1 kHz.…”

Section: Introductionmentioning

confidence: 99%

Controllable Charge-Transfer Mechanism at Push–Pull Porphyrin/Nanocarbon Interfaces

et al. 2019

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Ultrafast charge transfer at the interfaces between 5,15-donor-acceptor push-pull porphyrins (Por-tBu and Por-OC8) and nanocarbon materials in the form of fullerene (C60) and graphene carboxylate (GC) are investigated using femtosecond (fs) pump-probe spectroscopy with broadband capabilities. The strong photoluminescence (PL) quenching of the porphyrin indicates electron and/or energy transfer from the photoexcited porphyrin to the nanocarbon materials. More interestingly, the Stern-Volmer plots of PL quenching shows linear and nonlinear patterns upon increasing the concentration of GC or C60 in the porphyrin solution, respectively, clearly indicating static and a combination of static and dynamic quenching at the interfaces with these nanocarbon materials. Using femtosecond transient absorption (TA) spectroscopy, ultrafast electron transfer from a singlet-excited porphyrin to the nanocarbon materials is clearly identified by the fast ground state bleach recovery and the formation of cation radical species. Furthermore, a fs-TA study revealed that both porphyrins show very long-lived ground state bleach (GSB) and excited state absorption (ESA), which can be attributed to the triplet-state formation. This work provides new physical insights into the electron transfer process and its driving force in donor-accepter systems that include nanocarbon materials.

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Comparative Synthetic Strategies for the Generation of 5,10‐ and 5,15‐Substituted Push‐Pull Porphyrins

Cited by 16 publications

References 94 publications

Fourfold alkyl wrapping of a copper(II) porphyrin thwarts macrocycle π–π stacking in a compact supramolecular package

Fourfold alkyl wrapping of a copper(II) porphyrin thwarts macrocycle π–π stacking in a compact supramolecular package

Structural effects of meso-halogenation on porphyrins

Controllable Charge-Transfer Mechanism at Push–Pull Porphyrin/Nanocarbon Interfaces

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