Intramolecular and intermolecular photoinduced electron transfer in isomeric mesoporphyrin nitrobenzyl esters: structure and solvent effects

Fajarí, Lluís; Fors, Pere; Lang, Kamil; Nonell, Santi; Trull, Francesc R.

doi:10.1016/1010-6030(95)04192-3

Cited by 17 publications

(14 citation statements)

References 61 publications

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“…[14,15] A significant influence of the decreased polarity was not observed in compounds 10 and 11 that formed Jdimers in this noncoordinating solvent. Compound 12 showed only a moderate increase of F F due to equilibrium between the monomer and J-dimer.…”

Section: Introductioncontrasting

confidence: 48%

“…The ICT in AzaPc was also shown to be easily controlled by environmental properties, [13,14] similarly as was observed for PET in porphyrinoid systems. [15,16] In the presented work, several new AzaPc compounds which emit in the red portion of the UV/Vis spectrum were Abstract: New unsymmetrical zinc azaphthalocyanines, bearing one substituted aniline as a peripheral substituent, were prepared by using a statistical condensation approach. Both fluorescence and singlet oxygen quantum yields were extremely low in DMF (F F < 0.01, F D < 0.02, respectively), but increased after the addition of sulfuric acid, reaching values comparable to controls without aniline substituents (F F = 0.22-0.29, F D = 0.40-0.59, respec-prepared, and their fluorescence and singlet oxygen production with regards to pH is described.…”

Section: Introductionmentioning

confidence: 99%

“…In these cases, the unsymmetrical composition of the macrocyclic core (three pyrazines and one benzene ring) may influence the shape of the Q-band, but the positions of the Q x and Q y bands were apparently close to each other, this leading to the broadening and not to splitting ( Figure 2). Conjugation of the lone-pair of the donor center with a macrocyclic system was indicated by very small redshift of l max of pH sensitive compounds (e.g., 10-12) when compared with compounds without the donor (15,16). This In noncoordinating solvents, the peripheral amino substituents or pyridyl rings may be susceptible to coordination with the central zinc(II) to form supramolecular assemblies.…”

Section: Introductionmentioning

confidence: 99%

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Red‐Emitting Dyes with Photophysical and Photochemical Properties Controlled by pH

Novakova

Miletín

Kopecký

et al. 2011

Chemistry A European J

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New unsymmetrical zinc azaphthalocyanines, bearing one substituted aniline as a peripheral substituent, were prepared by using a statistical condensation approach. Both fluorescence and singlet oxygen quantum yields were extremely low in DMF (Φ(F)<0.01, Φ(Δ)<0.02, respectively), but increased after the addition of sulfuric acid, reaching values comparable to controls without aniline substituents (Φ(F)=0.22-0.29, Φ(Δ)=0.40-0.59, respectively). This behavior was attributed to the deactivation of excited states by intramolecular charge transfer from a donor site (aniline), which was blocked after protonation in acidic media. In the protonated form, all of the compounds efficiently emitted light with λ(em) in the region of 662-675 nm. The investigated compounds were anchored to dioleoylphosphatidylcholine (DOPC) unilamellar vesicles and showed response to buffer pH. They were highly fluorescent at low pH values and almost nonfluorescent in neutral solutions. The pK(a) values were determined in DOPC vesicles and ranged between 2.2 and 4.2.

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Section: Introductioncontrasting

confidence: 48%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Red‐Emitting Dyes with Photophysical and Photochemical Properties Controlled by pH

Novakova

Miletín

Kopecký

et al. 2011

Chemistry A European J

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“…At the same time, an enhancement of the thermodynamic feasibility of ICT due to increasing polarityo ft he medium with increasing volumeo fM eOH may lead to greaterq uenching of the excited states. [24] This phenomenono ccurreda th igherc oncentrations of analytes and did not significantly influencet he relationships discussed below. (22) 22 1cZn 0.0010 (658)-…”

Section: Sensing Propertiesi Nt Hfmentioning

confidence: 92%

Metal‐Cation Recognition in Water by a Tetrapyrazinoporphyrazine‐Based Tweezer Receptor

Lochman

Švec

Roh

et al. 2016

Chemistry A European J

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A series of zinc azaphthalocyanines with two azacrowns in a rigid tweezer arrangement were prepared and the fluorescence sensing properties were investigated. The size-driven recognition of alkali and alkaline earth metal cations was significantly enhanced by the close cooperation of the two azacrown units, in which both donor nitrogen atoms need to be involved in analyte binding to switch the sensor on. The mono- or biphasic character of the binding isotherms, together with the binding stoichiometry and magnitude of association constants (KA ), indicated specific complexation of particular analytes. Water solvation was shown to play an important role and resulted in a strong quenching of sensor fluorescence in the ON state. The lead compound was embedded into silica nanoparticles and advantageous sensing properties towards K(+) were demonstrated in water (λF =671 nm, apparent KA =82 m(-1) , increase of 17×), even in the presence of (supra)physiological concentrations of Na(+) and Ca(2+) .

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“…12,35,36 In order to distinguish between the changes in fluorescence intensity induced by protonation at different sites (azomethine × donor nitrogen), the experiment with sulfuric acid was performed first with s1Zn, s2Zn, s4Zn and s5Zn (Figure 6a, Figure S6). 12,37 The titrations with sulfuric acid had clearly biphasic character (Figure 6b). A decrease of Φ F was observed for all compounds at higher concentrations of sulfuric acid and was accompanied by typical changes in absorption spectra 36 indicating protonation of one azomethine nitrogen ( Figure S5).…”

Section: Protonation Of Nitrogensmentioning

confidence: 99%

Peripheral substitution as a tool for tuning electron-accepting properties of phthalocyanine analogs in intramolecular charge transfer

et al. 2015

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The intramolecular charge transfer (ICT), which is a pathway for excited state relaxation, was studied on the newly synthesized zinc(ii) complexes of tetrapyrazinoporphyrazines bearing one fixed donor (i.e., a dialkylamino substituent). The rest of the peripheral substituents on the core was designed with respect to their different electronic effects (OBu, neopentyl, StBu, COOBu). The photophysical (singlet oxygen and fluorescence quantum yields) and electrochemical (reduction potentials) properties were determined and compared within the series and with compounds that did not contain a donor moiety. The ICT efficiency correlated well with both the electron-deficient character of the core and the Hammett substituent constants σp. The most efficient ICT was observed for the core with the most electron-accepting substituent (COOBu), and the lowest ICT efficiency was detected for the least electron-deficient core (substituted by OBu). Titration of DMSO solutions of target compounds with H2SO4 indicated that basicity of the azomethine bridges was largely influenced by the character of the peripheral substituents while the dialkylamino donor center remained nearly unaffected. Furthermore, protonation of the donor nitrogen caused partial restoration of the fluorescence quantum yield (increase up to 90 times) due to blocking of ICT. The results implied that the ICT efficiency was strongly dependent on the electron-accepting properties of the core whose properties can be readily affected by suitable selection of peripheral substituents.

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Intramolecular and intermolecular photoinduced electron transfer in isomeric mesoporphyrin nitrobenzyl esters: structure and solvent effects

Cited by 17 publications

References 61 publications

Red‐Emitting Dyes with Photophysical and Photochemical Properties Controlled by pH

Red‐Emitting Dyes with Photophysical and Photochemical Properties Controlled by pH

Metal‐Cation Recognition in Water by a Tetrapyrazinoporphyrazine‐Based Tweezer Receptor

Peripheral substitution as a tool for tuning electron-accepting properties of phthalocyanine analogs in intramolecular charge transfer

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