scholarly journals The Influence of Some Axial Ligands on Ruthenium–Phthalocyanine Complexes: Chemical, Photochemical, and Photobiological Properties

2021 ◽  
Vol 7 ◽  
Author(s):  
Tássia Joi Martins ◽  
Laisa Bonafim Negri ◽  
Laena Pernomian ◽  
Kelson do Carmo Freitas Faial ◽  
Congcong Xue ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Transient Absorption ◽  
Ruthenium Complex ◽  
Spectroscopic Techniques ◽  
B16f10 Cell ◽  
Axial Ligands ◽  
Cell Extracts ◽  
Secondary Reactions ◽  
Murine Melanoma Cells ◽  
Potential Use

This work presents a new procedure to synthesize ruthenium–phthalocyanine complexes and uses diverse spectroscopic techniques to characterize trans-[RuCl(Pc)DMSO] (I) (Pc = phthalocyanine) and trans-[Ru(Pc)(4-ampy)2] (II) (4-ampy = 4-aminopyridine). The triplet excited-state lifetimes of (I) measured by nanosecond transient absorption showed that two processes occurred, one around 15 ns and the other around 3.8 μs. Axial ligands seemed to affect the singlet oxygen quantum yield. Yields of 0.62 and 0.14 were achieved for (I) and (II), respectively. The lower value obtained for (II) probably resulted from secondary reactions of singlet oxygen in the presence of the ruthenium complex. We also investigate how axial ligands in the ruthenium–phthalocyanine complexes affect their photo-bioactivity in B16F10 murine melanoma cells. In the case of (I) at 1 μmol/L, photosensitization with 5.95 J/cm2 provided B16F10 cell viability of 6%, showing that (I) was more active than (II) at the same concentration. Furthermore, (II) was detected intracellularly in B16F10 cell extracts. The behavior of the evaluated ruthenium–phthalocyanine complexes point to the potential use of (I) as a metal-based drug in clinical therapy. Changes in axial ligands can modulate the photosensitizer activity of the ruthenium phthalocyanine complexes.

scholarly journals Ruthenium-based PACT agents based on bisquinoline chelates: synthesis, photochemistry, and cytotoxicity

2021 ◽  
Author(s):  
Anja Busemann ◽  
Ingrid Flaspohler ◽  
Xue-Quan Zhou ◽  
Claudia Schmidt ◽  
Sina K. Goetzfried ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Singlet Oxygen ◽  
Cancer Cells ◽  
Cellular Uptake ◽  
Ruthenium Complex ◽  
Human Cancer ◽  
Light Irradiation ◽  
Quantum Yields ◽  
Light Activation ◽  
Human Cancer Cells

AbstractThe known ruthenium complex [Ru(tpy)(bpy)(Hmte)](PF6)2 ([1](PF6)2, where tpy = 2,2’:6’,2″-terpyridine, bpy = 2,2’-bipyridine, Hmte = 2-(methylthio)ethanol) is photosubstitutionally active but non-toxic to cancer cells even upon light irradiation. In this work, the two analogs complexes [Ru(tpy)(NN)(Hmte)](PF6)2, where NN = 3,3'-biisoquinoline (i-biq, [2](PF6)2) and di(isoquinolin-3-yl)amine (i-Hdiqa, [3](PF6)2), were synthesized and their photochemistry and phototoxicity evaluated to assess their suitability as photoactivated chemotherapy (PACT) agents. The increase of the aromatic surface of [2](PF6)2 and [3](PF6)2, compared to [1](PF6)2, leads to higher lipophilicity and higher cellular uptake for the former complexes. Such improved uptake is directly correlated to the cytotoxicity of these compounds in the dark: while [2](PF6)2 and [3](PF6)2 showed low EC50 values in human cancer cells, [1](PF6)2 is not cytotoxic due to poor cellular uptake. While stable in the dark, all complexes substituted the protecting thioether ligand upon light irradiation (520 nm), with the highest photosubstitution quantum yield found for [3](PF6)2 (Φ[3] = 0.070). Compounds [2](PF6)2 and [3](PF6)2 were found both more cytotoxic after light activation than in the dark, with a photo index of 4. Considering the very low singlet oxygen quantum yields of these compounds, and the lack of cytotoxicity of the photoreleased Hmte thioether ligand, it can be concluded that the toxicity observed after light activation is due to the photoreleased aqua complexes [Ru(tpy)(NN)(OH2)]2+, and thus that [2](PF6)2 and [3](PF6)2 are promising PACT candidates. Graphic abstract

scholarly journals Transient absorption spectroscopy using high harmonic generation: a review of ultrafast X-ray dynamics in molecules and solids

2019 ◽  
Vol 377 (2145) ◽  
pp. 20170463 ◽  
Author(s):  
Romain Geneaux ◽  
Hugo J. B. Marroux ◽  
Alexander Guggenmos ◽  
Daniel M. Neumark ◽  
Stephen R. Leone
Keyword(s):  
Time Scales ◽  
Harmonic Generation ◽  
Absorption Spectroscopy ◽  
Transient Absorption ◽  
High Harmonic ◽  
High Harmonic Generation ◽  
Transient Absorption Spectroscopy ◽  
Spectroscopic Techniques ◽  
X Rays ◽  
X Ray

Attosecond science opened the door to observing nuclear and electronic dynamics in real time and has begun to expand beyond its traditional grounds. Among several spectroscopic techniques, X-ray transient absorption spectroscopy has become key in understanding matter on ultrafast time scales. In this review, we illustrate the capabilities of this unique tool through a number of iconic experiments. We outline how coherent broadband X-ray radiation, emitted in high-harmonic generation, can be used to follow dynamics in increasingly complex systems. Experiments performed in both molecules and solids are discussed at length, on time scales ranging from attoseconds to picoseconds, and in perturbative or strong-field excitation regimes. This article is part of the theme issue ‘Measurement of ultrafast electronic and structural dynamics with X-rays’.

scholarly journals Photoinduced electron transfer processes of single-wall carbon nanotube (SWCNT)–based hybrids

Nanophotonics ◽  
2020 ◽  
Vol 9 (16) ◽  
pp. 4689-4701
Author(s):  
Lili Du ◽  
Wenjuan Xiong ◽  
Wai Kin Chan ◽  
David Lee Phillips
Keyword(s):  
Electron Transfer ◽  
Transient Absorption ◽  
Electronic Materials ◽  
Photophysical Properties ◽  
Functional Materials ◽  
Single Wall Carbon Nanotubes ◽  
Spectroscopic Techniques ◽  
Time Resolved ◽  
Single Wall Carbon ◽  
Electron Transfer Processes

AbstractIn this review, noncovalent functionalization of single-wall carbon nanotubes (SWCNTs) is briefly reviewed. The functional materials summarized here include metalloporphyrin derivatives, biomolecules and conjugated polymers. Notably, time-resolved spectroscopic techniques such as time-resolved fluorescence and transient absorption were employed to directly investigate the electron transfer and recombination processes between the functionalities and the SWCNTs. In addition, Raman spectroscopy is also useful to identify the interaction and the electron transfer direction between both the functionalities and the SWCNTs. An improved understanding of the mechanisms of these SWCNT-based nanohybrids in terms of their structural and photophysical properties can provide more insights into the design of new electronic materials.

scholarly journals Спектральное исследование фотодинамических процессов в системе C-=SUB=-60-=/SUB=--(н-метилпирролидон)-кислород

2021 ◽  
Vol 129 (12) ◽  
pp. 1493
Author(s):  
И.М. Кисляков ◽  
И.М. Белоусова ◽  
В.М. Киселев ◽  
И.В. Багров ◽  
А.М. Стародубцев ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Singlet Oxygen ◽  
Transient Absorption ◽  
Rapid Quenching ◽  
Quenching Rate ◽  
Broadband Absorption ◽  
Laser Pumping ◽  
Time Dependencies ◽  
Quenching Rate Constant

The processes of photoexcitation and energy transfer in an air-saturated solution of fullerene C60 in n-methylpyrrolidone are studied. With femtosecond laser pumping at a wavelength л(p) = 520 nm, transient absorption spectra were obtained in the range 470-750 nm. Broadband absorption is observed at л > 650 nm as a result of aggregation of fullerene molecules, characterized by a short decay time of the picosecond scale. The analysis of the time dependencies indicates the presence of several processes. Within the proposed interpretation, we state a remarkable reduction in the time of singlet-triplet intersystem crossing with an increase of nanocluster size while the rapid quenching of the singlet state varies only slightly. The quantum yield of the triplet state can therefore increase, reaching 0.14. The phosphorescence spectra of singlet oxygen with a maximum at л = 1276 nm were measured with LED excitation at various wavelengths in the range 370-625 nm. The lifetime and quenching rate constant of singlet oxygen in n-methylpyrrolidone are determined. The combined quantum yield of triplet fullerene and singlet oxygen in n-methylpyrrolidone is estimated as 0.74. The efficiency spectra of the singlet oxygen photosensibilization in the C60-(n-methylpyrrolidone)-oxygen system are obtained, indicating the increasing role of large nanoclusters in this process during aging of the solution.

scholarly journals Ultrafast Exciton Dynamics in Two Dimensional Covalent Organic Frameworks Reveals Size Dependence to Exciton Diffusion

2020 ◽  
Author(s):  
Nathan C. Flanders ◽  
Matthew S. Kirschner ◽  
Pyosang Kim ◽  
Thomas Fauvell ◽  
Austin Evans ◽  
...  
Keyword(s):  
High Performance ◽  
Transient Absorption ◽  
Domain Size ◽  
Spectroscopic Techniques ◽  
Two Dimensional ◽  
Exciton Dynamics ◽  
Singlet Exciton ◽  
Exciton Diffusion ◽  
Absorption Studies ◽  
Exciton Annihilation

<p>Large singlet exciton diffusion lengths are a hallmark of high performance in organic based devices such as photovoltaics, chemical sensors, and photodetectors. In this study, exciton dynamics of a two-dimensional covalent organic framework, COF- 5, is investigated using ultrafast spectroscopic techniques. Following photoexcitation, the COF-5 exciton decays via three pathways: 1) excimer formation (4 ± 2 ps), 2) excimer relaxation (160 ± 40 ps), and 3) excimer decay (>3 ns). Excitation fluence-dependent transient absorption studies suggest that COF-5 has a relatively large diffusion coefficient (0.08 cm2/s). Furthermore, exciton-exciton annihilation processes are characterized as a function of COF-5 crystallite domain size in four different samples, which reveal domain- size dependent exciton diffusion kinetics. These results reveal that exciton diffusion in COF-5 is constrained by its crystalline domain size. These insights indicate the outstanding promise of delocalized excitonic processes available in 2D COFs, which motivate their continued design and implementation into optoelectronic devices. </p>

Photoinduced Nitric Oxide and Singlet Oxygen Release from ZnPC Liposome Vehicle Associated with the Nitrosyl Ruthenium Complex: Synergistic Effects in Photodynamic Therapy Application

2009 ◽  
Vol 85 (3) ◽  
pp. 705-713 ◽  
Author(s):  
Daniela Silva Maranho ◽  
Renata Galvão de Lima ◽  
Fernando Lucas Primo ◽  
Roberto Santana da Silva ◽  
Antonio Claudio Tedesco
Keyword(s):  
Nitric Oxide ◽  
Photodynamic Therapy ◽  
Singlet Oxygen ◽  
Ruthenium Complex ◽  
Synergistic Effects ◽  
Oxygen Release

p-nitrobenzamide substituted phosphorus(V) porphyrins: synthesis and interactions with DNA

2005 ◽  
Vol 09 (07) ◽  
pp. 453-462 ◽  
Author(s):  
Mariusz P. Gajewski ◽  
Leszek Czuchajowski
Keyword(s):  
Dna Damage ◽  
Singlet Oxygen ◽  
Sodium Azide ◽  
Dna Cleavage ◽  
Electronic Communication ◽  
Laser Light ◽  
Axial Ligands ◽  
Dna Nicking ◽  
532 Nm

Four new phosphorus(V) porphyrins were designed and synthesized. The compounds were diaxially substituted with 4-nitrobenzamide. The axial ligands were attached to the P(V) center of the porphyrins through methylene linkers of different lengths. DNA titrations showed the expected porphyrin binding. When exposed to 532 nm laser light, which corresponds to the porphyrin Q band, the photosensitizers induced DNA nicking. Inhibition of the nicking by sodium azide suggested participation of singlet oxygen in the process. Photoexcitation with 305 nm laser light, which corresponds to absorption of 4-nitrobenzamide, also resulted in DNA damage. Due to the lack of electronic communication between the axial ligands and the porphyrin, the desired pathway of DNA cleavage was chosen by selecting a proper wavelength of the light used for photoexcitation. The activities of the porphyrins in photoinduced DNA nicking were very similar in both experiments: irradiation with 305 and 532 nm light, and were inversely correlated with the length of the linkers.

scholarly journals Vacancy-enhanced generation of singlet oxygen for photodynamic therapy

2019 ◽  
Vol 10 (8) ◽  
pp. 2336-2341 ◽  
Author(s):  
Shanyue Guan ◽  
Li Wang ◽  
Si-Min Xu ◽  
Di Yang ◽  
Geoffrey I. N. Waterhouse ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Photodynamic Therapy ◽  
Oxygen Vacancy ◽  
Singlet Oxygen ◽  
Band Gap ◽  
Ruthenium Complex

Oxygen vacancy introduced defects in the band gap of BiOBr–H allow facile electron transfer from a photo-excited ruthenium complex to the semiconductor, thereby increasing ROS yields and PDT efficiency.

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