scholarly journals Role of H-bond formation in the photoreactivity of curcumin

2008 ◽  
Vol 22 (2-3) ◽  
pp. 187-198 ◽  
Author(s):  
Luca Nardo ◽  
Roberta Paderno ◽  
Alessandra Andreoni ◽  
Már Másson ◽  
Tone Haukvik ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Light Exposure ◽  
Strong Dependence ◽  
Intramolecular Proton Transfer ◽  
Biological Action ◽  
Quantum Yields ◽  
Oxygen Generation ◽  
Oxygen Generator ◽  
Electronically Excited

Curcumin is the main constituent of curry. In its ground state it shows chemo-preventive, chemo-therapeutic and anti-inflammatory effects. For its immunostimulating action it has been considered for the development of drugs suitable for treating AIDS and cystic fibrosis. Further biological action is induced in curcumin by photoactivation: in suitable environmental conditions electronically excited curcumin can act as a singlet oxygen generator. Moreover, cytotoxicity is enhanced by light exposure and antibacterial effects are photosensitized. This work is aimed to understand the photobiological action of curcumin by elucidating the deactivation mechanisms of its first excited singlet state. In particular we find evidence of the role of tautomerization in the excited state by measuring fluorescence lifetimes and quantum yields for such compound dissolved in solvents of different polarity and H-bonding capability. Degradation quantum yield and singlet oxygen generation efficiency were also measured in acetonitrile and methanol. The results emphasize the strong dependence of the deactivation processes from the environment. The deactivation phenomenology can be fully explained by postulating intramolecular proton transfer in thecisenol conformer to be the leading non-radiative deactivation pathway.

Singlet oxygen generation of subphthalocyanine-fused dimer and trimer

2020 ◽  
Vol 24 (01n03) ◽  
pp. 211-219
Author(s):  
Rei Fujishiro ◽  
Hayato Sonoyama ◽  
Yuki Ide ◽  
Takuya Fujimura ◽  
Ryo Sasai ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Quantum Yields ◽  
Absorption Bands ◽  
Low Light ◽  
Oxygen Generation ◽  
Singlet Oxygen Generation ◽  
Near Ir ◽  
Interesting Class ◽  
High Fluorescence ◽  
Significant Wavelength

Subphthalocyanine (SubPc) macrocycles are known as an interesting class of nonplanar aromatic dyes. Despite documented high fluorescence and singlet oxygen quantum yields, the properties of SubPcs in photodynamic therapy (PDT) are underestimated, because their absorption bands do not reach a significant wavelength range. With this in mind, we combined a SubPc ring and a SubPc ring by introducing a common benzene ring and obtained a SubPc dimer (2) and trimer (3) with the Q-band at the near-IR region, owing to the expansion of the [Formula: see text] electron conjugated system. In this study, we reported 1O2 generation abilities of 2 and 3based on the applied absolute singlet oxygen quantum yields ([Formula: see text]absolute). Subsequent research revealed that 2 and 3 showed the potential to generate 1O2 to not only in toluene but also in DMSO. Although the photocytotoxicity of 2 and 3 were investigated upon photo-irradiation with a low light dose of approximately 1.5 J/cm2, 2 and 3 showed almost negligible toxic properties toward HEp2 cells.

Synthesis, characterization, photophysicochemical properties and theoretical study of novel zinc phthalocyanine containing four tetrathia macrocycles

2018 ◽  
Vol 22 (01n03) ◽  
pp. 77-87 ◽  
Author(s):  
Mohamad Albakour ◽  
Gülenay Tunç ◽  
Büşra Akyol ◽  
Sinem Tuncel Kostakoğlu ◽  
Savaş Berber ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Zinc Phthalocyanine ◽  
Quantum Yields ◽  
Energy Structure ◽  
Fluorescence Measurement ◽  
Oxygen Generation ◽  
Fluorescence Quantum Yields ◽  
H Nmr ◽  
Ft Ir ◽  
Phthalocyanine Derivative

In this work, Zn(II) phthalocyanine derivative (TTU-Pc) bearing 13-membered tetrathia macrocycles was synthesized, and the novel Zn(II) phthalocyanine derivative was fully characterized by elemental analysis and general spectroscopic methods such as MALDI-TOF mass, FT-IR, UV-vis and [Formula: see text]H-NMR. The synthesized phthalocyanine derivative has quite limited solubility in most of the common organic solvents. Fluorescence measurement was conducted for this Zn(II)phthalocyanine to estimate its fluorescence quantum yields. The singlet oxygen generation ability was also examined to investigate its photosensitizer properties. General trends were described for quantum yields of fluorescence, photodegradation and singlet oxygen quantum yields of this compound. The electrochemical properties of the molecule were investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV). In addition, the lowest energy structure, the electronic structure and frontier molecular orbitals were calculated in DFT and the excitation spectrum was obtained by TDDFT calculations. We found that our computational and experimental results were in agreement.

New heterogeneous photosensitizers with phthalocyanine molecules covalently linked to aminopropyl silica gel

2011 ◽  
Vol 15 (07n08) ◽  
pp. 718-726 ◽  
Author(s):  
Nina A. Kuznetsova ◽  
Olga A. Yuzhakova ◽  
Marina G. Strakhovskaya ◽  
Anna O. Shumarina ◽  
Anton S. Kozlov ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Silica Gel ◽  
Fluorescence Spectra ◽  
Quantum Yields ◽  
Absorption And Fluorescence Spectra ◽  
Oxygen Generation ◽  
E Coli ◽  
Singlet Oxygen Generation ◽  
Aqueous Suspensions ◽  
Covalently Linked

New heterogeneous photosensitizers were synthesized, in which phthalocyanines of zinc and aluminum, tetrasubstituted at non-peripheral positions with modified thiophenyl groups, were grafted to aminopropyl silica gel. The absorption and fluorescence spectra, and the quantum yields of fluorescence and photosensitized singlet oxygen generation were estimated for aqueous suspensions of these sensitizers. It is shown that upon photoexcitation, silica gel-bound phthalocyanines produce singlet oxygen and display photobactericidal activity against bacteria E. coli.

scholarly journals Absorption Characteristics and Quantum Yields of Singlet Oxygen Generation of Thioguanosine Derivatives

2018 ◽  
Vol 94 (4) ◽  
pp. 677-684 ◽  
Author(s):  
Shoma Miyata ◽  
Takeshi Yamada ◽  
Tasuku Isozaki ◽  
Hideyuki Sugimura ◽  
Yao-Zhong Xu ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Quantum Yields ◽  
Oxygen Generation ◽  
Singlet Oxygen Generation ◽  
Absorption Characteristics

scholarly journals A Singlet Oxygen Photogeneration and Luminescence Study of Unsymmetrically Substituted Mesoporphyrinic Compounds

2009 ◽  
Vol 2009 ◽  
pp. 1-10 ◽  
Author(s):  
Anabela Sousa Oliveira ◽  
Dumitru Licsandru ◽  
Rica Boscencu ◽  
Radu Socoteanu ◽  
Veronica Nacea ◽  
...  
Keyword(s):  
Singlet Oxygen ◽  
Photophysical Properties ◽  
Delayed Fluorescence ◽  
Quantum Yields ◽  
Mean Values ◽  
Oxygen Generation ◽  
Fluorescence Quantum Yields ◽  
Thermally Activated ◽  
Phosphorescence Emission ◽  
Photophysical Studies

This paper deals with a series of new unsymmetrically substituted mesoporphyrins: 5-(2-hydroxyphenyl)-10,15,20-tris-phenyl-21,23-H-porphyrin (TPPOHO), 5-(3-hydroxyphenyl)-10,15,20-tris-phenyl-21,23-H-porphyrin (TPPOHM), 5-(4-hydroxyphenyl)-10,15,20-tris-phenyl-21,23-H-porphyrin (TPPOHP), 5-(2-hydroxyphenyl)-10,15,20-tris-butyl-21,23-H-porphyrin (TBPOHO), and their parent nonsubstituted compounds, respectively, 5,10,15,20-tetrakis-phenyl-21,23-H-porphyrin (TPP) and 5,10,15,20-tetrakis-butyl-21,23-H-porphyrin (TBP). Several photophysical studies were carried out to access the influence of the unsymmetrical substitution at the porphyrinic macrocycle on porthyrin's photophysical properties, especially porthyrin's efficiency as singlet oxygen sensitizers. The quantum yields of singlet oxygen generation were determined in benzene (ΦΔ(TPP) = 0.66 ± 0.05;ΦΔ(TPPOHO) = 0.69 ± 0.04;ΦΔ(TPPOHM) = 0.62 ± 0.04;ΦΔ(TPPOHP) = 0.73 ± 0.03;ΦΔ(TBP) = 0.76 ± 0.03;ΦΔ(TBPOHO) = 0.73 ± 0.02) using the 5,10,15,20-tetraphenyl-21,23-H-porphine (ΦΔ(TPP) = 0.66) and Phenazine (ΦΔ(Phz) = 0.83) as reference compounds. Their fluorescence quantum yields were found to be (Φf(TPPOHO) = 0.10 ± 0.04;Φf(TPPOHM) = 0.09 ± 0.03;Φf(TPPOHP) = 0.13 ± 0.02;Φf(TBP) = 0.08 ± 0.03 andΦf(TBPOHO) = 0.08 ± 0.02 using 5,10,15,20-tetraphenyl-21,23-H-porphine as referenceΦf(TPP) = 0.13). Singlet state lifetimes were also determined in the same solvent. All the porphyrins presented very similar fluorescence lifetimes (mean values ofτS(withO2, air equilibrated) = 9.6 ± 0.3 nanoseconds and (withoutO2, argon purged) = 10.1 ± 0.6 nanoseconds, resp.). The phosphorescence emission was found to be negligible for this series of unsymmetrically substituted mesoporphyrins, but an E-type, thermally activated, delayed fluorescence process was proved to occur at room temperature.

scholarly journals A P-61 Black Widow Inspired Palladium Biladiene Complex for Efficient Sensitization of Singlet Oxygen Using Visible Light

Photochem ◽  
2022 ◽  
Vol 2 (1) ◽  
pp. 58-68
Author(s):  
Anthony T. Rice ◽  
Glenn P. A. Yap ◽  
Joel Rosenthal
Keyword(s):  
Visible Light ◽  
Singlet Oxygen ◽  
Heavy Atom ◽  
Spectroscopic Properties ◽  
Quantum Yields ◽  
Black Widow ◽  
Oxygen Generation ◽  
Promising Treatment ◽  
Cancerous Cells ◽  
Sensitization Efficiency

Photodynamic therapy (PDT) is a promising treatment option that ablates cancerous cells and tumors via photoinduced sensitization of singlet oxygen. Over the last few decades, much work has been devoted to the development of new photochemotherapeutic agents for PDT. A wide variety of macrocyclic tetrapyrrole based photosensitizers have been designed, synthesized and characterized as PDT agents. Many of these complexes have a variety of issues that pose a barrier to their use in humans, including biocompatibility, inherent toxicity, and synthetic hurdles. We have developed a non-traditional, non-cyclic, and non-aromatic tetrapyrrole ligand scaffold, called the biladiene (DMBil1), as an alternative to these traditional photosensitizer complexes. Upon insertion of a heavy atom such as Pd2+ center, Pd[DMBil1] generates singlet oxygen in substantial yields (ΦΔ = 0.54, λexc = 500 nm) when irradiated with visible light. To extend the absorption profile for Pd[DMBil1] deeper into the phototherapeutic window, the tetrapyrrole was conjugated with alkynyl phenyl groups at the 2- and 18-positions (Pd[DMBil2-PE]) resulting in a significant redshift while also increasing singlet oxygen generation (ΦΔ = 0.59, 600 nm). To further modify the dialkynyl-biladiene scaffold, we conjugated a 1,8-diethynylanthracene with to the Pd[DMBil1] tetrapyrrole in order to further extend the compound’s π-conjugation in a cyclic loop that spans the entire tetrapyrrole unit. This new compound (Pd[DMBil2-P61]) is structurally reminiscent of the P61 Black Widow aircraft and absorbs light into the phototherapeutic window (600–900 nm). In addition to detailing the solid-state structure and steady-state spectroscopic properties for this new biladiene, photochemical sensitization studies demonstrated that Pd[DMBil2-P61] can sensitize the formation of 1O2 with quantum yields of ΦΔ = 0.84 upon irradiation with light λ = 600 nm. These results distinguish the Pd[DMBil2-P61] platform as the most efficient biladiene-based singlet oxygen photosensitizer developed to date. When taken together, the improved absorption in the phototherapeutic window and high singlet oxygen sensitization efficiency of Pd[DMBil2-P61] mark this compound as a promising candidate for future study as an agent of photodynamic cancer therapy.

Bis-indole substituted phthalocyanines: Photophysical and photochemical properties

2020 ◽  
Vol 25 (01) ◽  
pp. 66-74
Author(s):  
Kevser Harmandar ◽  
Esra N. Kaya ◽  
Mehmet F. Saglam ◽  
Ibrahim F. Sengul ◽  
Devrim Atilla
Keyword(s):  
Photodynamic Therapy ◽  
Singlet Oxygen ◽  
Spectral Data ◽  
Quantum Yields ◽  
Oxygen Generation ◽  
Fluorescence Quantum Yields ◽  
H Nmr ◽  
Singlet Oxygen Generation ◽  
Photochemical Properties ◽  
C Nmr

Tetra substituted peripheral and non-peripheral Zn(II) phthalocyanines were successfully synthesized employing 4-(bis(3-methyl-1H-indol-2-yl)methyl)phenol as a starting material. The structure of these synthesized compounds was confirmed using 1H NMR, [Formula: see text]C NMR, infrared (IR), UV-vis, and MALDI-TOF spectral data. The photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen generation) properties of all synthesized peripheral and non-peripheral compounds were investigated in order to determine the potential of these compounds for application in photodynamic therapy.

The Role of Gold Nanoparticles' Aspect Ratio in Plasmon-Enhanced Luminescence and Singlet Oxygen Generation Rate by Mo6 Clusters

2021 ◽  
Author(s):  
Evgeniya D. Novikova ◽  
Yuri A. Vorotnikov ◽  
Nazar A. Nikolaev ◽  
Alphiya R Tsygankova ◽  
Michael A. Shestopalov ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Aspect Ratio ◽  
Singlet Oxygen ◽  
Oxygen Production ◽  
Oxygen Generation ◽  
Singlet Oxygen Generation ◽  
Oxygen Production Rate ◽  
Plasmon Enhanced Luminescence ◽  
Enhanced Luminescence

Here we present a study on the effect of the aspect ratio (AR) of gold nanoparticles on the emission intensity and singlet oxygen production rate of hexamolybdenum cluster-doped silica particles....

A quantitative structure–property relationship (QSPR) study of singlet oxygen generation by pteridines

2016 ◽  
Vol 15 (6) ◽  
pp. 801-811 ◽  
Author(s):  
Andrey A. Buglak ◽  
Taisiya A. Telegina ◽  
Mikhail S. Kritsky
Keyword(s):  
Dipole Moment ◽  
Singlet Oxygen ◽  
Quantum Yields ◽  
Quantitative Structure ◽  
Oxygen Production ◽  
Structure Property ◽  
Oxygen Generation ◽  
Singlet Oxygen Generation ◽  
Structure Property Relationship ◽  
Qspr Study

Singlet oxygen production quantum yields of pteridine photosensitizers were analyzed with the QSPR method. The ability of pterins and flavins to generate1O2in D2O correlated withEHOMOand electronegativity, as well as with the dipole moment and some other parameters.

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