Photophysical Behavior of Zinc(II) Tetraphenylporphyrin Covalently Incorporated in a Cholesterol-Bearing Polymethacrylate

Abstract

Photophysical behavior of a zinc(I1) tetraphenylporphyrin (ZnTPP) moiety in a copolymer of 0.1 mol % zinc(I1) 5-[4-(6-methacryloyloxyhexanoyloxy)phenyl]-10,15,20triphenylporphynate (ZnTPP-C,-MA) and 99.9 mol % cholesteryl 6-methacryloyloxyhexanate (Chol-C,-MA) was investigated in comparison with that of monomeric ZnTPP-C,-MA. Pendant cholesterol (Chol) groups in the copolymer form stacks in n-hexane (a poor solvent for the copolymer), while no Chol stacks are formed in benzene (a good solvent). The absorption maxima of the Soret and Q bands of monomeric ZnTPP-C5-MA were solvent dependent, i.e. the maxima in n-hexane were 7.6 nm' shorter than those in benzene. In contrast, no such solvent dependence was observed for the polymer-bound ZnTPP moiety. Spectral profiles for the fluorescence bands for the polymer-bound ZnTPP moiety and monomeric ZnTPP-C,-MA were very different in n-hexane, i.e. the relative intensity of the 0-0 to 0-1 fluorescence bands for the former was 0.52 while that for the latter was 1.10. The triplet excited lifetime for the polymer-bound Zn-TPP moiety at room temperature was much longer in nhexane (22 ms) than in benzene (3.7 ms), while the fluoatures (22,23).Cholesterol-bearing polymethacrylates, homoand copolymers of cholesteryl 6-methacryloyloxyhexanate (Chol-C,-MA), form cholesterol (Chol) microdomains in n-hexane,

Thermally Activated Delayed Fluorescence in Fullerenes

“…For a given fluorophore, TADF is usually much weaker than its PF. Although known for many years, TADF continues to be a rare phenomenon, with a few observations in some xanthene dyes, 6,9,10 aromatic ketones 11,12 and thiones, 13,14 metal porphyrins, 15 and aromatic hydrocarbons 16–18 …”

“…8 For a given fluorophore, TADF is usually much weaker than its PF. Although known for many years, TADF continues to be a rare phenomenon, with a few observations in some xanthene dyes, 6,9,10 aromatic ketones 11,12 and thiones, 13,14 metal porphyrins, 15 and aromatic hydrocarbons. [16][17][18] The remarkable photophysical properties of fullerene C 70 , specifically for the T very close to 1, 19 the small E ST gap, 20 and the long intrinsic phosphorescence lifetime, 21 led to the discovery of an exceptionally strong TADF in this molecule.…”

“…For strong TADF to occur, the cycle S 1 → T 1 → S 1 must repeat several times before photon emission or nonradiative decay can take place. To show this, it is convenient to present the TADF process as the following sequence (SCHEME 2): where the quantum yield of singlet formation is defined by EQUATION (15). With this kinetic analysis, it is possible to determine several parameters.…”

Thermally activated delayed fluorescence as a cycling process between excited singlet and triplet states: Application to the fullerenes

“…3 For a given fluorophore, TADF is usually much weaker than its PF. Although known for many years, TADF continues to be a rare phenomenon, with a few observations in some xanthene dyes, 1,4,5 aromatic ketones 6,7 and thiones, 8,9 metal porphyrins, 10 and aromatic hydrocarbons. [11][12][13] The remarkable photophysical properties of fullerene C 70 , specifically the ⌽ T very close to one, the small ⌬E ST gap and the long intrinsic phosphorescence lifetime, lead to the discovery of an exceptionally strong TADF in this molecule.…”

Synthetic N-substituted metal aza-macrocyclic complexes: properties and applications

“…The photophysical behavior of zinc(II) tetraphenylporphyrin (ZnTPP) in a copolymer of 0.1 mol% zinc(II) 5-[4-(6-methacryloyloxyhexanoyloxy)phenyl]-10,15,20-triphenylporphynate (ZnTPP-C-5-MA) and 99.9 mol% cholesteryl-6-methacryloyloxyhexanate (Chol-C-5-MA) has been investigated and compared with that of monomeric ZnTPP-C-5-MA [43]. The absorption maxima of the Soret and Q-bands of monomeric ZnTPP-C-5-MA are solvent dependent, that is the maxima in n-hexane are 7.6 nm shorter than those in benzene.…”