scholarly journals Formation, Photophysics, and Photochemistry of Anionic Lanthanide(III) Mono- and Bisporphyrins

Molecules ◽  
2019 ◽  
Vol 24 (7) ◽  
pp. 1309 ◽  
Author(s):  
Muhammad Imran ◽  
Melitta Kiss ◽  
Zsolt Valicsek ◽  
Ottó Horváth
Keyword(s):  
Coordination Compounds ◽  
Room Temperature ◽  
Continuous Wave ◽  
Water Soluble ◽  
Quantum Yields ◽  
Excitation Wavelength ◽  
Time Resolved ◽  
Visible Irradiation ◽  
Photochemical Properties ◽  
Water Soluble Porphyrin

Since water-soluble porphyrin complexes of lanthanides(III) have proved to be promising for medical applications (e.g., luminescence imaging, photodynamic therapy, and theranostics), the investigation of the formation, photophysical, and photochemical properties of such coordination compounds provides useful pieces of information for their potential usage. Steady-state and time-resolved fluorometry, UV–Vis absorption spectroscopy, and continuous-wave photolysis were utilized for this purpose. 5,10,15,20-Tetrakis(4-sulfonatophenyl)porphyrin formed mono- and bisporphyrin complexes with samarium(III), europium(III), and gadolinium(III) as representatives in the middle of the lanthanide series. The special photoinduced behavior of these compounds was mostly determined by the position of the metal center, which was located out of the ligand plane, thus distorting it. Besides, the photochemical and, especially, photophysical features of the corresponding mono- and bisporphyrin complexes were similar because, in the latter species, two monoporphyrins were connected by a weak metal bridge between the peripheral sulfonato substituents (tail-to-tail dimerization). The formation of these coordination compounds and the transformation reactions between the mono- and bisporphyrins were rather slow in the dark at room temperature. These processes were accelerated by visible irradiation. However, dissociation and, especially, redox degradation were the main photoreactions in these systems, although with low quantum yields. Additionally, depending on the excitation wavelength, new types of photoproducts were also detected.

Photophysical and photochemical properties of the water-soluble porphyrin complexes of metals of the platinum group

1999 ◽  
Vol 66 (4) ◽  
pp. 583-587 ◽  
Author(s):  
V. V. Vasil'ev ◽  
I. A. Blinova ◽  
I. V. Golovina ◽  
S. M. Borisov
Keyword(s):  
Water Soluble ◽  
Photochemical Properties ◽  
Platinum Group ◽  
Water Soluble Porphyrin

scholarly journals Effect of Some Substituents Increasing the Solubility of Zn(II) and Al(III) Phthalocyanines on Their Photophysical Properties

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
A. A. Chernonosov ◽  
E. A. Ermilov ◽  
B. Röder ◽  
L. I. Solovyova ◽  
O. S. Fedorova
Keyword(s):  
Absorption Spectra ◽  
Structural Changes ◽  
Water Solubility ◽  
Transient Absorption ◽  
Photophysical Properties ◽  
Water Soluble ◽  
Quantum Yields ◽  
Carboxyl Groups ◽  
Transient Absorption Spectra ◽  
Photochemical Properties

Water solubility of phthalocyanines (Pcs) usually increases by the introduction of charged or carboxy substituents in the peripheral positions of the macrocycle. As a result, such structural changes influence their photophysical and photochemical properties as photosensitizers. Phthalocyanines substituted with four or eight terminal carboxyl groups and having in some cases additional eight positive charges (water soluble phthalocyanines) were studied in order to evaluate the spectroscopic and photophysical effects of these side residues on the chromophore properties. The quantum yield of singlet oxygen (O12) generation, the triplet-triplet absorption, and the transient absorption spectra were measured and linked to the structure of the substituents. It was shown that charged substituents did not change the quantum yields ofO12generation but decrease its lifetimes. The introduction of the charged substituents not only increases the water solubility but also significantly changes absorption, fluorescence, and transient absorption spectra of water soluble Pcs.

Understanding the Photoluminescence Mechanism of Carbon Dots

MRS Advances ◽  
2017 ◽  
Vol 2 (51) ◽  
pp. 2927-2934 ◽  
Author(s):  
Zhoufeng Jiang ◽  
Marta J. Krysmann ◽  
Antonios Kelarakis ◽  
Petr Koutnik ◽  
Pavel Anzenbacher ◽  
...  
Keyword(s):  
Carbon Dots ◽  
Quantum Yields ◽  
Excitation Wavelength ◽  
Time Resolved ◽  
Light Emitting ◽  
Dependent Component ◽  
Different Types ◽  
Photoluminescence Mechanism ◽  
Time Resolved Photoluminescence ◽  
Absolute Quantum

ABSTRACTThe carbon dots were investigated to reveal their light-emitting mechanism. The fluorescence spectra of carbon dots show typically two different types of photoluminescence: the excitation-independent component in the short wavelength, and the excitation-dependent component in the longer wavelength. The UV-Vis spectrum of carbon dots shows the absorption maximum of 340 nm which should be accredited to the n-π* transition of the carbonyl group in carbon dots. Absolute quantum yields of carbon dots dispersed in Polyvinyl alcohol is around 15% when the excitation wavelength is less than 425 nm, but decreases continuously when the excitation wavelength increases. The decay lifetimes of the carbon dots also show an abrupt change at excitation wavelength 425 nm. Time resolved photoluminescence was implemented from 31K to 291K to study the photoluminescence decay dynamics of carbon dots, resulting in the continuously decreasing of the lifetime as the temperature increases.

Photocatalytic hydrogen production based on a water-soluble porphyrin derivative as sensitizer and a series of Wilkinson type complexes as catalysts

2016 ◽  
Vol 20 (08n11) ◽  
pp. 1200-1206 ◽  
Author(s):  
Athanassios A. Panagiotopoulos ◽  
Efthymios G. Fasoulakis ◽  
Eleftheria E. Vardalachaki ◽  
Athanassios G. Coutsolelos
Keyword(s):  
Hydrogen Production ◽  
Hydrogen Evolution ◽  
Electron Donor ◽  
Systematic Study ◽  
Water Soluble ◽  
Rhodium Complexes ◽  
Visible Irradiation ◽  
Water Soluble Porphyrin ◽  
First Time ◽  
Evolution Systems

Herein, we report photochemical hydrogen evolution systems consisting of various rhodium based catalysts with Wilkinson type structures, Zn metalated porphyrins and fluorescein as photosensitizers and triethanolamine as a sacrificial electron donor in acetonitrile/H2O (1:1) solution. Since rhodium complexes 1 and 2 are used for the first time as catalysts in this type of systems, a systematic study was performed in order to elucidate the best conditions for H2 production. Upon visible irradiation hydrogen production was detected and the best results were obtained at pH 7 when dye P3 and catalyst 1 were used with a TON of 61, after 48 h and in the presence of dye P1 and catalyst 2 with a TON of 69, after the 48 h.

Excitation-Wavelength Dependent and Time-Resolved Photoluminescence Studies of Europium Doped GaN Grown by Interrupted Growth Epitaxy (IGE)

2005 ◽  
Vol 866 ◽  
Author(s):  
Ei Ei Nyein ◽  
Uwe Hömmerich ◽  
Chanaka Munasinghe ◽  
Andrew J. Steckl ◽  
John M. Zavada
Keyword(s):  
Room Temperature ◽  
Growth Conditions ◽  
Excitation Wavelength ◽  
Time Resolved ◽  
Pl Intensity ◽  
Photoluminescence Studies ◽  
Two Peaks ◽  
Time Resolved Photoluminescence ◽  
Cycling Time ◽  
The Eu

AbstractThe emission properties of Eu doped GaN thin films prepared by interrupted growth epitaxy (IGE) were investigated through excitation-wavelength dependent and time-resolved photoluminescence (PL) studies. Under above-gap excitation (333-363 nm) large differences were observed in the Eu3+ PL intensity and spectral features as a function of Ga shutter cycling time. The overall strongest red Eu3+ PL intensity was obtained from a sample grown with a Gashutter cycling time of 20 minutes. The main Eu3+ emission line originating from 5D0→ 7F2 transition was composed of two peaks located at 620 nm and 622 nm, which varied in relative intensity depending on the growth conditions. The room-temperature emission lifetimes of the samples were non-exponential and varied from ∼50 νs to ∼200 νs (1/e lifetimes). Under resonant excitation at 471 nm (7F0→5D2) all samples exhibited nearly identical PL spectra independent of Ga shutter cycling time. Moreover, the Eu3+ PL intensities and lifetimes varied significantly less compared to above-gap excitation. The excitation wavelengths dependent PL results indicate the existence of different Eu3+ centers in GaN: Eu, which can be controlled by the Ga shutter cycling time.

A fluorescence study of the solute–solvent interactions of aminochalcones in a room-temperature ionic liquid

2013 ◽  
Vol 85 (7) ◽  
pp. 1451-1463 ◽  
Author(s):  
Kotni Santhosh ◽  
G. Krishnamurthy Grandhi ◽  
Snigdha Ghosh ◽  
Anunay Samanta
Keyword(s):  
Ionic Liquid ◽  
Room Temperature ◽  
Solvent Polarity ◽  
Fluorescence Decay ◽  
Room Temperature Ionic Liquid ◽  
Excitation Wavelength ◽  
Solvation Dynamics ◽  
Time Resolved ◽  
Solvent Interactions ◽  
The One

Unlike most other electron donor–acceptor (EDA) molecules, aminochalcones exhibit unusual solvent polarity-dependent fluorescence behavior. The photophysical behavior of two aminochalcones, namely, 4-aminochalcone (AC) and 4-dimethylaminochalcone (DMAC), has been studied in a viscous room-temperature ionic liquid (IL), 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim][PF6], by steady-state and time-resolved fluorescence techniques. The observation of a single emission band in viscous IL, which is similar to the one observed in less viscous polar conventional solvents, suggests no twisting is necessary for the formation of the charge-transfer state from which the emission of aminochalcones originates. The fluorescence decay profiles, solvation dynamics, and excitation-wavelength-dependent emission behavior of AC are found to be quite different from those of DMAC in the IL. The observed difference is attributed to specific H-bonding interaction between AC and [bmim][PF6].

Dye Mixtures for Ultrafast Wavelength Shifters

1994 ◽  
Vol 348 ◽  
Author(s):  
S. Cangopadhyay ◽  
N. Barashkov ◽  
L. Liu ◽  
C. Palsule ◽  
W. Borst ◽  
...  
Keyword(s):  
Absorption Spectrum ◽  
Fluorescence Spectra ◽  
Continuous Wave ◽  
Quantum Yields ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Epoxy Polymers ◽  
Decay Times ◽  
The Mean ◽  
Coumarin Dyes

ABSTRACTWe have produced fast wavelength shifters using mixtures of various Coumarin dyes with DCM in epoxy-polymers (DGEBA+HHPA) and measured the properties of these wavelength shifters. The particular mixtures were chosen because there is a substantial overlap between the emission spectrum of Coumarin and the absorption spectrum of DCM. The continuous wave and time-resolved fluorescence spectra have been studied as a function of component concentration to optimize the decay times, emission peaks and quantum yields. The mean decay times of these mixtures are in the range of 2.5-4.5 ns. The mean decay time increases with an increase in Coumarin concentration at a fixed DCM concentration or with a decrease in DCM concentration at a fixed Coumarin concentration. This indicates that the energy transfer is radiative at lower relative DCM concentrations and becomes non-radiative at higher DCM concentrations.

scholarly journals Two-Photon Photodynamic Therapy by Water-Soluble Self-Assembled Conjugated Porphyrins

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Kazuya Ogawa ◽  
Yoshiaki Kobuke
Keyword(s):  
Photodynamic Therapy ◽  
Singlet Oxygen ◽  
Cross Section ◽  
Water Soluble ◽  
Photon Absorption ◽  
Time Resolved ◽  
Two Photon Absorption ◽  
Two Photon ◽  
Luminescence Measurement ◽  
Water Soluble Porphyrin

Studies on two-photon absorption (2PA) photodynamic therapy (PDT) by using three water-soluble porphyrin self-assemblies consisting of ethynylene-linked conjugatedbis(imidazolylporphyrin) are reviewed. 2PA cross-section values in water were obtained by an open aperture Z-scan measurement, and values were extremely large compared with those of monomeric porphyrins such as hematoporphyrin. These compounds were found to generate singlet oxygen efficiently upon one- as well as two-photon absorption as demonstrated by the time-resolved luminescence measurement at the characteristic band of singlet oxygen at 1270 nm and by using its scavenger. Photocytotoxicities for HeLa cancer cells were examined and found to be as high as those of hematoporphyrin, demonstrating that these compounds are potential candidates for 2PA-photodynamic therapy agents.

scholarly journals Investigation and detection of cyanobacterial Cr-phycoerythrin by laser based techniques

2014 ◽  
Vol 79 (2) ◽  
pp. 185-198 ◽  
Author(s):  
Bratislav Marinkovic ◽  
Ambra Delneri ◽  
Maja Rabasovic ◽  
Mira Terzic ◽  
Mladen Franko ◽  
...  
Keyword(s):  
Thermal Lens ◽  
High Sensitivity ◽  
Injection System ◽  
Quantum Yields ◽  
Excitation Wavelength ◽  
Lower Sensitivity ◽  
Time Resolved ◽  
Technical Parameters ◽  
Fluorescence Quantum Yields ◽  
High Fluorescence

The application of a high-sensitivity method of time resolved laser induced fluorescence (TR-LIF) and Flow-injection system by thermal lens spectrometry (FIA-TLS) for the analysis of Cr-Phycoerythrin (Cr-PE) isolated from a proprietary cyanobacterium is presented. In the excitation wavelength range (340-470 nm) fluorescent spectra exhibit a pronounced maximum at 575 nm. Another maximum, at about 600 nm can be also observed. The obtained results are used to verify the technical parameters of the used thermal lens technique, which is complementary to spectrofluorimetry and subject to lower sensitivity in case of high fluorescence quantum yields and photolability of measured compounds.

Sign in / Sign up

Export Citation Format

Share Document