Spatially resolved micro-photoluminescence imaging of porphyrin single crystals

Marin, Dawn M.; Castaneda, Jose; Kaushal, Meesha; Kaouk, Ghallia; Jones, Daniel S.; Walter, Michael G.

doi:10.1016/j.cplett.2016.06.057

Cited by 2 publications

(2 citation statements)

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“…They typically serve as starting materials for post-cyclization modification of porphyrins [28][29][30][31][32][33][34] but have also found applications in their own right, e.g., as photosensitizers in photodynamic therapy [35]. The crystal structures of several 5,15-disubstituted free base porphyrins have been previously reported, including the parent 5,15-diphenylporphyrin (H 2 11) [36], variously substituted 5,15-diarylporphyrins such as 5,15-bis(p-pentyloxyphenyl)porphyrin (AFIFOM) [37], -bis(o-aminophenyl)porphyrin (CUYCOQ), and -bis(p-carbomethoxyphenyl)porphyrin (AQIQOI), [38] as well as 5,15-dialkylporphyrins (alkyl = ethyl (SAZDUU), n-butyl (SAZFAQ) [39]) and 5,15-bis(2-thienyl)porphyrin (REVQIT) [40]. A related structural analysis of free base and diacid mono- (12) and diphenylporphyrins has been published, which included the structure of the bistrifluoroacetate of 5,15-bis(3,5-dimethoxyphenyl)porphyrin (MANJAN), the sole prior example of a 5,15-disubstituted porphyrin diacid [25].…”

Section: Introductionmentioning

confidence: 99%

Weak Interactions and Conformational Changes in Core-Protonated A2- and Ax-Type Porphyrin Dications

et al. 2020

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Individual chemical motifs are known to introduce structural distortions to the porphyrin macrocycle, be it in the core or at the periphery of the macrocycle. The interplay when introducing two or more of these known structural motifs has been scarcely explored and is not necessarily simply additive; these structural distortions have a chance to compound or negate to introduce new structural types. To this end, a series of compounds with complementary peripheral (5,15-disubstitution) and core (acidification) substitution patterns were investigated. The single-crystal X-ray structures of 18 5,15-diphenylporphyrin, 5,15-diphenylporphyrindi-ium diacid, and related compounds are reported, including the first example of a 5,15-dialkylporphyrindi-ium. Normal-coordinate structural decomposition (NSD) analysis is used for a detailed analysis of the conformation of the porphyrin subunit within the crystal structures. An elongation of porphyrin macrocycles along the C5,C15- axis (B2g symmetry) is observed in all of the free base porphyrins and porphyrin dications; distance across the core is around 0.3 Å in the free base and diacid compounds, and more than doubled in 5,15-dipentylporphyrin and 5,15-dipentylporphyrindi-ium diacid. While the free base porphyrins are largely planar, a large out-of-plane distortion can be observed in 5,15-diphenylporphyrin diacids, with the expected “projective saddle” shape characteristic for such systems. The combination of these two distortions (B2u and B2g) from regular porphyrin structure results in a macrocycle best characterized in the chiral point-group D2. A rare structural type of a cis-hydrogen bond chelate is observed for 5,15-dipentylporphyrindi-ium diacid, which adopts an achiral C2v symmetry. Crystallographic data indicate that the protonated porphyrin core forms hydrogen bonding chelates (N-H⋯X⋯H-N) to counter-anions. Weaker interactions, such as induced intramolecular C-H⋯O interactions from the porphyrin periphery are described, with distances characteristic of charge-assisted interactions. This paper offers a conceptual framework for accessing porphyrin macrocycles with designable distortion and symmetry, useful for the selective perturbation of electronic states and a design-for-application approach to solid state porphyrin materials.

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Section: Introductionmentioning

confidence: 99%

Weak Interactions and Conformational Changes in Core-Protonated A2- and Ax-Type Porphyrin Dications

et al. 2020

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“…As mentioned above, the origins of light emission from organic semiconductors have been previously explored using conventional spectroscopic and microscopic approaches. [17][18][19] The previously employed methods are however limited by diffraction to spatial resolutions on the order of a few hundred nanometers with driving sources in the visible-near IR region of the spectrum. In the case of perylene films, the subject of this work, the recorded PL spectra exhibit a complex multi-peak structure that arises from the recombination of intramolecular and intermolecular excitons, with contributions from vibronic sub-bands.…”

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confidence: 99%