180779-39-9Relevant academic research and scientific papers
Self-assembly of zinc aminoporphyrins
Gardner, Mark,Guerin, Andrea J.,Hunter, Christopher A.,Michelsen, Ulrike,Rotger, Carmen
, p. 309 - 316 (1999)
The aniline-zinc porphyrin interaction is an order of magnitude weaker than the corresponding pyridine-zinc porphyrin interaction, but it is still strong enough to cause self-assembly of zinc aminoporphyrins in solution. Three isomeric systems are reporte
Influence of the solvent and metal center on supramolecular chirality induction with bisporphyrin tweezer receptors. Strong metal modulation of effective molarity values
Pintre, Inmaculada C.,Pierrefixe, Simon,Hamilton, Alex,Valderrey, Virginia,Bo, Carles,Ballester, Pablo
scheme or table, p. 4620 - 4635 (2012/05/20)
We describe the synthesis of a bisporphyrin tweezer receptor 1H 4 and its metalation with Zn(II) and Rh(III) cations. We report the thermodynamic characterization of the supramolecular chirality induction process that takes place when the metalated bisporphyrin receptors coordinate to enantiopure 1,2-diaminocyclohexane in two different solvents, toluene and dichloromethane. We also performed a thorough study of several simpler systems that were used as models for the thermodynamic characterization of the more complex bisporphyrin systems. The initial complexation of the chiral diamine with the bisporphyrins produces a 1:1 sandwich complex that opens up to yield a simple 1:2 complex in the presence of excess diamine. The CD spectra associated with the 1:1 and 1:2 complexes of both metalloporphyrins, 1Zn2 and 1Rh2, display bisignate Cotton effects when the chirogenesis process is studied in toluene solutions. On the contrary, in dichloromethane solutions, only 1Zn2 yields CD-active 1:1 and 1:2 complexes, while the 1:2 complex of 1Rh2 is CD-silent. In both solvents, porphyrin 1Zn2 features a stoichiometrically controlled chirality inversion process, which is the sign of the Cotton effect of the 1:1 complex is opposite to that of the 1:2 complex. In contrast, porphyrin 1Rh2 affords 1:1 and 1:2 complexes in toluene solutions with the same sign for their CD couplets. Interestingly, in both solvents, the signs of the CD couplets associated with the 1:1 sandwich complexes of 1Zn 2 and 1Rh2 are opposite. The amplitudes of the CD couplets are higher for 1Zn2 than for 1Rh2. This observation is in agreement with 1Rh2 having a smaller extinction coefficient than 1Zn2. We performed DFT-based calculations and assigned molecular structures to the 1:1 and 1:2 complexes that explain the observed signs for their CD couplets. Unexpectedly, the quantification of the thermodynamic stability of the two metallobisporphyrin/ diamine 1:1 sandwich complexes revealed the existence of interplay between effective molarity values (EM) and the strength of the intermolecular interaction (Km; N...Zn or N...Rh) used in their assembly. The EM for the N...Rh(III) intramolecular interaction is 3 orders of magnitude smaller than that for the N...Zn(II) interaction, both of which are embedded in the same scaffold of the 1M2 bisporphyrin receptor.
Stabilization of the charge-separated states of covalently linked zinc porphyrin-triphenylamine-[60]fullerene
El-Khouly Dr., Mohamed E.,Han Dr., Ki-Jong,Kay, Kwang-Yol,Fukuzumi Prof. Dr., Shunichi
experimental part, p. 1726 - 1734 (2011/11/12)
Spectroscopic, redox, computational, and electron transfer reactions of the covalently linked zinc porphyrin-triphenyl-amine-fulleropyrrolidine system are investigated in solvents of varying polarity. An appreciable interaction between triphenylamine and the porphyrin π system is revealed by steady-state absorption and emission, redox, and computational studies. Free-energy calculations suggest that the light-induced processes via the singlet-excited porphyrin are exothermic in benzonitrile, dichlorobenzene, toluene, and benzene. The occurrence of fast and efficient charge-separation processes (≈ 1012 s 1) via the singlet-excited porphyrin is confirmed by femtosecond transient absorption measurements in solvents with dielectric constants ranging from 25.2 (benzonitrile) to 2.2 (benzene). The rates of the charge separation processes are much less solvent-dependent, which suggests that the charge-separation processes occur at the top region of the Marcus parabola. The lifetimes of the singlet radical-ion pair (70-3000 ps at room temperature) decrease substantially in more polar solvents, which suggests that the charge-recombination process is occurring in the Marcus inverted region. Interestingly, by utilizing the nanosecond transient absorption spectral technique we can obtain clear evidence about the existence of triplet radical-ion pairs with relatively long lifetimes of 0.71 μs (in benzonitrile) and 2.2 μs (in o-dichlorobenzene), but not in toluene and benzene due to energetic considerations. From the point of view of mechanistic information, the synthesized zinc porphyrin-triphenylamine-fulleropyrrolidine system has the advantage that both the lifetimes of the singlet and triplet radical-ion pair can be determined.
