Spectroscopy of interchromophoric interactions in self-organized porphyrin and chlorin complexes

Borczyskowski, C. von; Rempel, U.; Zenkevich, É. I.; Шульга, А. М.; Chernook, A. V.

doi:10.1016/0022-2860(95)08683-m

Cited by 8 publications

(4 citation statements)

References 12 publications

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“…the appearance of additional components in the Soret band splitting, are observed. Finally, as in the triads [35] there is no evidence for a strong coupling of the B-transitions of the complexed free bases with those of the dimer subunits.…”

Section: Electronic Absorptionmentioning

confidence: 83%

“…However, this point of view is hard to adopt without any other additional proof since the formation of structure a only for the 2(ZnHTPP) 2 • H2P(mPyr) 4 pentad looks like an exclusion among other combinations of the dimers and the free bases. For instance, the similar pentad 2(ZnOEP)2Ph • H2P(mPyr) 4 shows only two components in the Soret region with the redshift (A ~, -----630 cm -I) with respect to (ZnOEP)2Ph which is usual for the ligation [35].…”

Section: Electronic Absorptionmentioning

confidence: 95%

“…4a). The structure of the dimer Soret band in the triads has been shown to reflect most likely the strong dipole-dipole coupling of the intense B-transitions of the dimer subunits [34] in a geometry distorted by the two-point coordination with the opposite metapyridyl substituents [35]. The difference between the pentad and the triad might be introduced by different geometries of the two-point coordination.…”

Section: Electronic Absorption Of 2(znhtpp) 2 • H2thp(mpyr)mentioning

confidence: 99%

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Formation and optical properties of self-organized pentameric porphyrin arrays

Chernook

Rempel

Borczyskowski

et al. 1996

Chemical Physics Letters

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Principles of formation, electronic absorption and fluorescence spectra are reported for self-organized pentameric arrays of tetrapyrrolic macrocycles. In these arrays two molecules of Zn-porphyrin dimers, Zn(II)l,4-bis [5-(10,15,20+tri-p-hexylphenylporphyrinyl)]-benzene ((ZnHTPP) 2) are bound via one molecule of a tetrapyridyl-substituted free base of porphyrin or tetrahydroporphyrin. The process of self-assembly is based on the twofold coordination of the central Zn ions !n the dimer with the nitrogen atoms of the pyridyl rings in the free base which is strong enough to make the complexes stable at room temperature. The formation of the complexes can be followed by changes in the absorption bands of (ZnHTPP) 2 characteristic of an axial extra-ligation of Zn-porphyrins with pyridine or pyridyl-substituted compounds. The spectral behavior of the free bases in the pentads is determined by a non-planar distortion of their macrocycle caused by the two-point binding with the dimers. The fluorescence intensity of the Zn-porphyrin dimer decreases essentially upon complexation with the tetrapyridyl-substituted free bases. This quenching effect is assigned to a singlet-silaglet energy transfer from the complexed Zn-porphyrin dimers to the free base subunit in the pentad.

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Section: Electronic Absorptionmentioning

confidence: 83%

Section: Electronic Absorptionmentioning

confidence: 95%

Section: Electronic Absorption Of 2(znhtpp) 2 • H2thp(mpyr)mentioning

confidence: 99%

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Formation and optical properties of self-organized pentameric porphyrin arrays

Chernook

Rempel

Borczyskowski

et al. 1996

Chemical Physics Letters

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“…Aside from the formation processes, the role of the solvents used and the stability of the H 2 P molecules attached to the ligand shell were investigated, both in solution by competitive aggregate formation in comparison to multiporphyrin complexes [41][42][43] and in a polymer film deposited on a silicon wafer [44] (see the Supporting Information). There are two basic results: 1) ligand coverage, and thus, the number of accessible attachment sites are controlled by the solvent polarity and 2) attachment of H 2 P does not result in a permanent change in the physical properties of the QDs.…”

Section: Influence Of Qd Size On Pl Quenching Of Cdse/zns Qds By H 2 Pmentioning

confidence: 99%

Formation Principles and Ligand Dynamics of Nanoassemblies of CdSe Quantum Dots and Functionalised Dye Molecules

et al. 2011

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Functional dye molecules, such as porphyrins, attached to CdSe quantum dots (QDs) through anchoring meso-pyridyl substituents, form quasi-stable nanoassemblies. This fact results in photoluminescence (PL) quenching of the QDs both due to Förster resonance energy transfer (FRET) and the formation of non-radiative surface states under conditions of quantum confinement (non-FRET). The formation process is in competition with the ligand dynamics. At least two timescales are found for the formation of the assemblies: 1) one faster than 60 s attributed to saturation of empty attachment sites and 2) one slower than 600 s, which is attributed to a reorganisation of the tri-n-octylphosphine oxide (TOPO) ligand shell. Finally, this process results in almost complete exchange of the TOPO shell by porphyrin dye molecules. Following a Stern-Volmer analysis, we established a microscopic description of PL quenching and assembly formation. Based on this formalism, we determined the equilibrium constant for assembly formation between QDs and the pyridyl-functionalised dye molecules to be K ≈ 10(5) - 10(7) M(-1), which is several orders of magnitude larger than that of the TOPO ligands. Our results give additional insights into the non-FRET PL quenching processes involved and show that the QD surface is inhomogeneous with respect to the involved attachment and detachment processes. In comparison with other methods, such as NMR spectroscopy, the advantage of our approach is that ligand dynamics can be investigated at extremely low ratios of dye molecules to QDs.

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