Porphyrin metal complexes with a large dipole moment

Агеева, Т. А.; Bush, Aleksander A.; Golubev, Denis V.; Горшкова, А. С.; Kamentsev, K. E.; Койфман, О. И.; Rumyantseva, V. D.; Sigov, Aleksander S.; Fomichev, V.V.

doi:10.1016/j.jorganchem.2020.121355

Cited by 10 publications

(6 citation statements)

References 22 publications

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“…This yields an interaction strength prefactor η = μ 2 4 π ϵ normalr ϵ 0 of roughly 150 eV Å 3 . The transition dipole moment of nBSQ is large in contrast to other molecular dyes, for example, porphyrin (∼6 Debye) , and perylene (∼8 Debye), which is consistent with the higher extinction coefficient …”

Section: Methodssupporting

confidence: 71%

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Structural Disorder as the Origin of Optical Properties and Spectral Dynamics in Squaraine Nano-Aggregates

et al. 2022

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In contrast to regular J-and H-aggregates, thin film squaraine aggregates usually have broad absorption spectra containing both J-and H-like features, which are favorable for organic photovoltaics. Despite being successfully applied in organic photovoltaics for years, a clear interpretation of these optical properties by relating them to specific excited states and an underlying aggregate structure has not been made. In this work, by static and transient absorption spectroscopy on aggregated n-butyl anilino squaraines, we provide evidence that both the red-and blue-shifted peaks can be explained by assuming an ensemble of aggregates with intermolecular dipole−dipole resonance interactions and structural disorder deriving from the four different nearest neighbor alignments�in sharp contrast to previous association of the peaks with intermolecular charge-transfer interactions. In our model, the next-nearest neighbor dipole−dipole interactions may be negative or positive, which leads to the occurrence of J-and Hlike features in the absorption spectrum. Upon femtosecond pulse excitation of the aggregated sample, a transient absorption spectrum deviating from the absorbance spectrum emerges. The deviation finds its origin in the excitation of two-exciton states by the probe pulse. The lifetime of the exciton is confirmed by the band integral dynamics, featuring a single-exponential decay with a lifetime of 205 ps. Our results disclose the aggregated structure and the origin of red-and blue-shifted peaks and explain the absence of photoluminescence in squaraine thin films. Our findings underline the important role of structural disorder of molecular aggregates for photovoltaic applications.

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Section: Methodssupporting

confidence: 71%

“…This yields an interaction strength prefactor of roughly 150 eV Å 3 . The transition dipole moment of nBSQ is large in contrast to other molecular dyes, for example, porphyrin (∼6 Debye) , and perylene (∼8 Debye), which is consistent with the higher extinction coefficient …”

Section: Methodssupporting

confidence: 71%

Structural Disorder as the Origin of Optical Properties and Spectral Dynamics in Squaraine Nano-Aggregates

et al. 2022

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“…The red‐shifted H‐aggregates are not unprecedented, they were described elsewhere, [40,45] but we cannot find any structural analogies with our case in those works. Non‐planar complexes of etioporphyrin with oxovanadium ion are polar, but the dipole moment is relatively weak (2.32 D calculated for VO‐EtioP‐II isomer) [46] . The Soret‐band shifts associated with hydrogen‐bonded aggregate formation are assumed to be negligible [7] …”

Section: Resultsmentioning

confidence: 99%

Molecular And Solid‐State Structure Of Oxovanadium(IV) Etioporphyrin‐III

Pakhomov,

Koptyaev,

Yunin

et al. 2023

ChemistrySelect

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Oxovanadium(IV) etioporphyrin‐III, VO‐EtioP‐III is an important member of the petroporphyrin family. It can be isolated from crude oil or synthesized de novo from the dipyrromethene precursors, the latter being the approach we used in our research. The molecular structure of VO‐EtioP‐III was for the first time characterized by single‐crystal X‐ray diffraction. Both terminal alkyls and the axial oxygen atom protrude in the same direction relative to the molecular plane, while rear side of the molecule remains almost flat. This results in a peculiar centrosymmetric packing (space group P21/c, monoclinic system with four molecules per unit cell), in which back‐to‐back oriented molecules form the parallel‐plane dimers. The powder X‐ray diffraction data indicate that the VO‐EtioP‐III films deposited by vacuum evaporation retain a very strong texture, with all molecules standing vertically on the substrate surface. The absorption spectra of films differ from the solution spectra by a large redshift of the Soret‐ and Q‐ band (~30 nm) with hypo‐ and hyperchromic effects, respectively. The former band strongly broadens due to multiple splitting to within 350–520 nm, which is followed by a change of the color from purple (in diluted solutions) to brawn (in films or crystals).

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“…Nowadays, such kind of molecules (VO 2+ porphyrins, 28 VO 2+ and TiO 2+ phthalocyanines, 29,30 etc.) find many applications related to the control of band-alignment at the electrode surface, 31 in dye-synthetized solar cells, 32 electrets, 33 etc. Metal-porphyrins with an anion bound to the coordinated metallic ion are no longer planar since the anion protrudes outside the macrocycle plane.…”

Section: Introductionmentioning

confidence: 99%