Conformational folding induced by π–π interaction in a series of flexible dyads consisting of isomeric mesoporphyrin nitrobenzyl esters

Colominas, Carles; Eixarch, Lisbeth; Fors, Pere; Lang, Kamil; Nonell, Santi; Teixidó, Jordi; Trull, Francesc R.

doi:10.1039/p29960000997

Cited by 4 publications

(3 citation statements)

References 52 publications

(1 reference statement)

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“…The dependence on OPV length suggests that the bridge unit specifically interacts with the porphyrin. Similar π−π interactions have been observed between porphyrins and other aromatic systems. 2d,,− For example, the presence of a noncoordinated benzene molecule has been reported to perturb the stereochemistry of a Mn−porphyrin through a weak π interaction . A similar effect could result in charge redistribution at the porphyrin nitrogen atoms, generating an additional chemical environment and, thus, a second N 1s peak.…”

Section: Discussionmentioning

confidence: 63%

X-ray Photoelectron Spectroscopy as a Probe of Intermolecular Interactions in Porphyrin Polymer Thin Films

2001

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High-resolution X-ray photoelectron spectroscopy (XPS) has been applied to a series of free-base and Zn-porphyrin polymers in which the macrocycles are separated by oligo(phenylene vinylene) units (OPV) of different, controllable lengths. Neat films of all the Zn-porphyrin polymers unexpectedly reveal two peaks in the N 1s XPS region ( approximately 400 eV). The peak areas vary with the length of the OPV bridge, suggesting an intermolecular interaction between the porphyrin and linker subunits. A series of XPS analyses were performed to identify the different interactions taking place in these thin films. To inhibit interpolymer interactions, one of the polymers was incorporated into a nonconjugated PMMA matrix, collapsing the N1s spectrum to a single peak at 398.0 eV, relative to the neat film signals at 397.8 and 400.1 eV. In a conjugated matrix of OPV, two peaks remain at 401.7 and 399.5 eV. Extensive vacuum drying of the neat film leads to a single peak at 398.3 eV, suggesting loss of trapped solvent molecules. Ultimately, we attribute the lower energy signal of the neat films to solvent ligation, and the higher energy peak is attributed to interactions between the porphyrins and conjugated bridges on nearby polymer chains. This interpretation is successfully applied to the N 1s XPS data from a previously reported Zn-porphyrin oligomer-based multilayer array.

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Section: Discussionmentioning

confidence: 63%

X-ray Photoelectron Spectroscopy as a Probe of Intermolecular Interactions in Porphyrin Polymer Thin Films

2001

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“…On the other hand, significant shieldings ranging from −0.27 to −0.76 ppm were found for the propionate units instead of the negligible effect in compound 1 . An additive time-averaged shielding exerted by one phenyl unit on the other, as judged from the spectral data reported for mesoporphyrin dibenzyl ester, can be estimated as −0.2 ppm . The higher upfield shift therefore suggests the establishment of some type of interactions bringing both propionate 3,5-didodecyloxyphenyl rings into proximity.…”

Section: Resultsmentioning

confidence: 94%

“…The higher upfield shift therefore suggests the establishment of some type of interactions bringing both propionate 3,5-didodecyloxyphenyl rings into proximity. The π−π stacking of a phenyl ring either with the central porphyrin ring, giving rise to “folded” conformations, or with the other phenyl ring seem unlikely, given the electron-rich character of all the rings involved …”

Section: Resultsmentioning

confidence: 99%

Multiple Interactions in the Self-Association of Porphyrin Discotic Mesogens

2008

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The conformational preferences and the self-associational behaviors of two hemin-derived porphyrin compounds, a tetramethyl ester and a liquid crystalline tetrakis(3,5-didodecyloxyphenyl)ester, have been studied by UV/vis and (1)H NMR spectroscopy in solution. Results indicate that the 3,5-didodecyloxyphenyl units play an important role in both the conformational and the self-associational behaviors of the mesomorphic tetraester. In the monomeric, nonassociated species, the two propionic 3,5-didodecyloxyphenyl esters establish mutual CH/pi interactions that restrict the fluctuative behavior of the chains. In the dimeric, self-associated species, intermolecular CH/pi interactions occur in addition to the pi-pi stacking of the porphyrin cores. The temperature-dependent addition of side CH/pi interactions to the pi-pi stacking of the porphyrin rings accounts for the observed tightening and for the slower dynamics of the dimeric structure. The relationship between the self-associational behavior and the mesomorphism of the hemin-derived porphyrin tetraesters is also discussed.

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Synthesis, Characterization and Weak Intramolecular Interactions of Porphyrins Bearing Nucleobases

et al. 2003

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whereas the spectra of their zinc complexes show 7 nm red shifts of the Soret bands compared to that of ZnTPP. The emission spectra of Zn-1 and Zn-2 are independent of excitation wavelength. From combination of the evidence of absorption * and emission spectra it is suggested the existence of intramolecular metal-n interaction in Zn-1 and Zn-2. The results of conformational analysis agreed quite nicely with that of experiments, thus it was further to validate the experimental conclusions.

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Conformational folding induced by π–π interaction in a series of flexible dyads consisting of isomeric mesoporphyrin nitrobenzyl esters

Cited by 4 publications

References 52 publications

X-ray Photoelectron Spectroscopy as a Probe of Intermolecular Interactions in Porphyrin Polymer Thin Films

X-ray Photoelectron Spectroscopy as a Probe of Intermolecular Interactions in Porphyrin Polymer Thin Films

Multiple Interactions in the Self-Association of Porphyrin Discotic Mesogens

Synthesis, Characterization and Weak Intramolecular Interactions of Porphyrins Bearing Nucleobases

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