Delayed Fluorescence Due to Annihilation of Triplets Produced in Recombination of Photo-Generated Ions

Angulo, Gonzalo; Grampp, Günter; Neufeld, A. A.; Burshteǐn, A. I.

doi:10.1021/jp0342475

Cited by 33 publications

(46 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Ru(bpy)3Cl2 [21] was utilized as a reference for determination of the fluorescence quantum yields. Transient absorption measurements were carried out on a laser kinetic equipment described elsewhere [22]. Photochemical experiments were carried out with 3.5-cm 3 argon-saturated solutions in 1-cm cells at r.t., continuously homogenized by magnetic stirring.…”

mentioning

confidence: 99%

Photophysical and photocatalytic behavior of nickel(II) 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin

Major

Horváth

Fodor

et al. 2016

Inorganic Chemistry Communications

View full text Add to dashboard Cite

Kinetically inert cationic Ni(II)TMPyP 4+ (H2TMPyP 4+ = 5,10,15,20-tetrakis(methylpyridinium-4-yl)porphyrin) displayed a characteristic fluorescence (τ = 1.2-1.4 ns, Φ = 2.0×10 -3 ), which was quenched with triethanolamine (TEOA) in a static way. This complex proved to be an efficient photocatalyst in the system containing TEOA and methylviologen (MV 2+ ) as electron donor and acceptor, respectively. Interestingly, however, deviating from the behavior of the analogous Co(III) and Mn(III) complexes in such a system, TEOA did not dinamically quench the triplet excited state of Ni(II)TMPyP 4+ (τ = 6.31 μs), hence no reduction of the metal center occured upon irradition. Instead, in the presence of this electron donor (at 1×10 -3 M) the excited-state lifetime dramatically increased (to τ = 36.6 μs), indicating the formation of a Ni(II)TMPyP 4+ -TEOA associate. This longer-lived triplet was efficiently quenched by MV 2+ (kq = 9.9×10 6 M -1 s -1 ), leading to the formation of MV •+ . The overall quantum yield of this one-step photoassisted electron transfer is considerably high (Φ = 0.011-0.013 at Soret-band irradiation). Hence, this system, combined with a suitable cocatalyst, may be applicable for visible light-driven hydrogen generation from water.

show abstract

mentioning

confidence: 99%

Photophysical and photocatalytic behavior of nickel(II) 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin

Major

Horváth

Fodor

et al. 2016

Inorganic Chemistry Communications

View full text Add to dashboard Cite

show abstract

“…Ru(bpy)3Cl2 [11] was utilized as a reference for determination of the fluorescence quantum yields. Transient absorption measurements were carried out on a laser kinetic equipment describe elsewhere [12]. Photochemical experiments were carried out with 3.5-cm 3 argon-saturated solutions in 1-cm cells at r.t., continuously homogenized by magnetic stirring.…”

mentioning

confidence: 99%

Photophysical and photocatalytic behavior of cobalt(III) 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin

Fodor¹,

Horváth²,

Fodor³

et al. 2014

Inorganic Chemistry Communications

View full text Add to dashboard Cite

Although kinetically inert cationic Co(III)TMPyP 5+ (H2TMPyP 4+ = 5,10,15,20-tetrakis(methylpyridinium-4-yl)porphyrin) was considered earlier to be very weakly emissive, both the spectrum and the lifetime of its fluorescence could be determined. Besides, this complex proved to be favorable for outer-sphere photoinduced reduction of the metal center in the presence of triethanolamine (TEOA) as electron donor quenching the triplet excited state of this metalloporphyrin. The corresponding cobalt(II) porphyrin formed in this way was also photoactive; it forwarded an electron to a suitable acceptor (e.g., methylviologen) upon irradiation, regenerating the starting complex. Hence, this system may be a candidate for hydrogen generation from water by utilization of visible light. Metalloporphyrins play important roles in nature, due to their special spectral, coordination and redox features. Their advantageous photoinduced properties can also be exploited in various photocatalytic procedures [1]. Water-soluble derivatives can be utilized in environmentally benign systems not containing organic solvents. Kinetically inert in-plain metalloporphyrins, in which the metal center coplanarly fits into the cavity of the ligand, may offer promising possibilities for realization of photocatalytic systems based on outer-sphere electron transfer [2]. The so-called hyper-porphyrins can be especially interesting in this respect, due to their distorted structure, which may increase the (photo)redox reactivity of these complexes. From water-soluble metalloporphyrins of this type, photoredox reactions of manganese(III) complexes were thoroughly studied [1,3,4], while scarce attention was paid to the corresponding cobalt(III) porphyrins in this respect. Keywords: cobalt(III) porphyrinPhotocatalytic oxidation of the sulfide content of a wastewater to sulfate was studied with Co(III)TMPyP 5+ , Mn(III)TMPyP 5+ , and Fe(III)TMPyP 5+ (H2TMPyP 4+ = 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin) [5]. Upon irradiation in the range of the Soretbands, the cobalt(III) complex proved to be the most efficient, but the results have not been interpreted. This metalloporphyrin can also connect to the chain of DNA and oxidatively split it in the presence of suitable electron acceptors [6]. Since cationic manganese(III) porphyrins proved to be efficient photocatalysts in the presence of appropriate electron donors (such as EDTA and TEOA) and methylviologen as electron acceptor [1,3,7], cationic cobalt(III) porphyrins, the other characteristic representatives of water-soluble hyper-porphyrins, are also worth investigating in this respect. Hence, in this work, some photophysical and photochemical properties of Co(III)TMPyP 5+ were studied, also confirming its photocatalytic behavior, which may be utilized in water-splitting by solar radiation.The compounds used for our experiments were of reagent grade. Water purified in a Millipore/Milli-Q system was applied as solvent. Stock solutions of Co(III)TMPyP 5+ were prepared by in situ generation ...

show abstract

“…Such is the influence that for the lower channels of the reaction in the MIR, the maximum of the reactivity is shifted away from contact creating a layer of strong recombination probability few Angstroms away from the contact distance s. 2 This effect has been shown experimentally. 3,4 The solvent relaxation time expression is as follows:…”

Section: Theoretical Modelmentioning

confidence: 99%

“…2 Experimental scrutiny of these theories is only now being performed. [3][4][5][6][7] It has been shown how the viscosity and the magnetic field modulate reactions. For example, it has been observed that recombination efficiency depends on the viscosity of the medium non-monotonically as a combined effect of the molecular transport and the spatial characteristics of the electron transfer reactions.…”

Section: Introductionmentioning

confidence: 99%

Influence of the excitation light intensity on the rate of fluorescence quenching reactions: pulsed experiments

Angulo

Milkiewicz

Kattnig

et al. 2017

Phys. Chem. Chem. Phys.

View full text Add to dashboard Cite

The effect of multiple light excitation events on bimolecular photo-induced electron transfer reactions in liquid solution is studied experimentally. It is found that the decay of fluorescence can be up to 25% faster if a second photon is absorbed after a first cycle of quenching and recombination. A theoretical model is presented which ascribes this effect to the enrichment of the concentration of quenchers in the immediate vicinity of fluorophores that have been previously excited. Despite its simplicity, the model delivers a qualitative agreement with the observed experimental trends. The original theory by Burshtein and Igoshin (J. Chem. Phys., 2000, 112, 10930-10940) was created for continuous light excitation though. A qualitative extrapolation from the here presented pulse experiments to the continuous excitation conditions lead us to conclude that in the latter the order of magnitude of the increase of the quenching efficiency upon increasing the light intensity of excitation, must also be on the order of tens of percent. These results mean that the rate constant for photo-induced bimolecular reactions depends not only on the usual known factors, such as temperature, viscosity and other properties of the medium, but also on the intensity of the excitation light.

show abstract

Delayed Fluorescence Due to Annihilation of Triplets Produced in Recombination of Photo-Generated Ions

Cited by 33 publications

References 28 publications

Photophysical and photocatalytic behavior of nickel(II) 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin

Photophysical and photocatalytic behavior of nickel(II) 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin

Photophysical and photocatalytic behavior of cobalt(III) 5,10,15,20-tetrakis(1-methylpyridinium-4-yl)porphyrin

Influence of the excitation light intensity on the rate of fluorescence quenching reactions: pulsed experiments

Contact Info

Product

Resources

About