Structure, electronic and vibrational spectra and aromaticity of hemiporphyrazine and its hydrates: A density functional theory study

Захаров, А. В.; Stryapan, Mikhail G.; Islyaikin, M. K.

doi:10.1016/j.theochem.2009.03.030

Cited by 19 publications

(27 citation statements)

References 41 publications

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“…↔ S 1 transitions that are normally symmetry forbidden in the isolated species 4,9. While the participation of emissive triplet states cannot be excluded, we anticipate that the multiwavelength luminescence properties of HpH 2 Zn(OTf) 2 and HpH 2 are a result of emissive S 2 → S 0…”

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confidence: 93%

“…These wavelengths are similar to those predicted for S 0 → S 2 and S 0 → S 1 transitions in HpH 2 . 4,9 To evaluate the potential role of aggregation in the concentration-dependent photophysical properties of HpH 2 Zn-(OTf) 2 , serial dilutions were conducted in DMSO (Supporting Information, Figure S5). In contrast to the results obtained in pure methanol (Figure 6), these dilutions obeyed Beer's law over the entire visible region (Supporting Information, Figure S5).…”

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confidence: 99%

“…Taken together, these results suggest the presence of enhanced S 0 ↔ S 1 transitions in aggregated hemiporphyrazines due to the presence of excitonic coupling with S 0 ↔ S 2 transitions. 4,9 Given the growing interest in hemipophyrazine-based materials as nonlinear optical devices, 17,19 . Fluorescence polarization of randomly deposited microcrystalline materials using excitation at 350 nm, an excitation cutoff filter at 420 nm, and plane-polarized excitation and emission with an angle of incidence = 0°.…”

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confidence: 99%

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Excitonic Luminescence of Hemiporphyrazines

et al. 2012

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Metal-free hemiporphyrazine (HpH2) is a notoriously insoluble material possessing interesting photophysical properties. Here we report the synthesis, structure, and photophysical properties of an octahedral zinc trans-ditriflate hemiporphyrazine complex "HpH2Zn(OTf)2" that contains a neutral hemiporphyrazine ligand. The photophysical properties of hemiporphyrazine are largely unaffected by introduction of zinc(II) triflate, but a dramatic increase in solubility is observed. HpH2Zn(OTf)2 therefore provides a convenient model system to evaluate the impact of aggregation on the photophysical properties of hemiporphyrazine. Soluble aggregates and crystalline materials containing planar hemiporphyrazines exhibit relatively strong absorbance of visible light (450-600 nm) and red luminescence (600-700 nm). Hemiporphyrazine monohydrate (HpH2·H2O), in contrast, has a nonplanar "saddleshaped" conformation that exhibits very little absorbance of visible light in solution or in the solid state. Upon photoexcitation at 380 nm, HpH2Zn(OTf)2 and HpH2 exhibit multiwavelength emissions centered at 450 and 650 nm. Emissions at 450 nm are highly anisotropic, while emissions at 650 nm are fully depolarized with respect to a plane-polarized excitation source. Taken together, our results suggest that excitonic coupling of aggregated and crystalline hemiporphyrazines results in increased absorbance and emission of visible light from S0 S1 transitions that are usually symmetry forbidden in isolated species. In contrast to previously proposed theories involving excited-state intramolecular proton transfer, we propose that the multiple-wavelength luminescent emissions of HpH2Zn(OTf)2 and HpH2 are due to emissive S1 and S2 states in aggregated and crystalline hemiporphyrazines. These results may provide a better understanding of the nonlinear optical properties of these materials in solution and in the solid state.

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Excitonic Luminescence of Hemiporphyrazines

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“…[1][2][3][4][5][6] Commonly used DFT calculations often allow to establish the most energetically favorable tautomer and then the preference is discussed in light of fundamental concepts of chemistry. Intramolecular hydrogen bonding is one of the most important issues among them for such objects.…”

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confidence: 99%

Intramolecular Hydrogen Bonding and Electronic Structure of Thiadiazole Annulated Hemihexaphyrazine

Otlyotov¹,

Merlyan²,

Veretennikov³

et al. 2018

MHC

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“…Therefore multiloop conjugation systems, which can be highlighted in Hps molecules, stimulate considerable theoretical interest. [16][17][18] Moreover, the presence of quinoxaline fragments in Mcs structure could enlarge the conjugation chain and expand their coordination abilities. However, Mcs of the ABAB-type with quinoxaline rings have not been studied due to the lack of preparative methods of their synthesis.…”

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confidence: 99%