Experimental studies on the determination of the dipole moments of some different laser dyes

Ghazy, R.; Azim, Saleh A.; Shaheen, Mohamed E.; El-Mekawey, F.

doi:10.1016/s1386-1425(03)00205-1

Cited by 60 publications

(16 citation statements)

References 20 publications

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“…This is consistent with the fact that these atoms provide the strongest dipole vector component in all the molecules considered [33]. In addition to this we have also calculated the Onsager's cavity radius by the formula [34] 3…”

Section: Methods II (Molecular-microscopic Solvent Polarity Parameter supporting

confidence: 82%

Photophysical properties and estimation of ground and excited state dipole moments of 7-diethylamino and 7-diethylamino-4-methyl coumarin dyes from absorption and emission spectra

Husain

Sindhu²,

Tandon³

2012

Eur. J. Chem.

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Section: Methods II (Molecular-microscopic Solvent Polarity Parameter supporting

confidence: 82%

Photophysical properties and estimation of ground and excited state dipole moments of 7-diethylamino and 7-diethylamino-4-methyl coumarin dyes from absorption and emission spectra

Husain

Sindhu²,

Tandon³

2012

Eur. J. Chem.

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“…The change in dipole moment upon excitation was calculated from the slope of the plot (slope = 902 cm −1 ) and the cavity radius is Δμ = 2.45 Debye, indicating the polar nature of the excited singlet state. Bakhshiev's and Kawski-Chamma-Viallet equations [47][48][49][50][51] have been used for the treatment of observed spectral shifts to determine the ground and excited state dipole moments of POPOP.…”

Section: Determination Of Dipole Momentsmentioning

confidence: 99%

Photophysical Parameters, Excitation Energy Transfer, and Photoreactivity of 1,4-Bis(5-phenyl-2-oxazolyl)benzene (POPOP) Laser Dye

El‐Daly

Elazim

El-Mekawey

et al. 2012

International Journal of Photoenergy

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The effect of solvents on the absorption and emission spectra of 1,4-bis(5-phenyl-2-oxazolyl)benzene (POPOP) laser dye has been studied in various solvents at 298 K. A bathochromic shift was observed in absorption and fluorescence spectra upon increase of solvent polarity, which indicates that this transition is π-π *. The ground and excited state dipole moments were calculated as 2.23 and 6.34 Debye, respectively. The dye solution in MeOH, n-heptane, and methyl isobutyl ketone gives laser emission in the blue region upon excitation by a 337.1 nm nitrogen pulse; the gain coefficient and emission cross section as well as normalized photostability have been determined. Excitation energy transfer from POPOP to rhodamine B and fluorescine was studied to improve the laser emission from these dyes. Such an energy transfer dye laser system (ETDL) obeys a long range columbic energy transfer mechanism with a critical transfer distance, R 0 , of 25 and 33Å and k q equal to 10.4 × 10 12 and 26.2 × 10 12 M −1 s −1 for the POPOP/RB and POPOP/fluorescine pair, respectively. The POPOP dye is highly photostable in polar protic and polar aprotic solvents, while it displays photodecomposition in chloromethane solvent via formation of a contact ion pair. The photochemical quantum yield and rate of photodecomposition depend on the electron affinity of solvent.

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“…Since we are concerned with molecules in solvents, especially in an aqueous system, the effect of electronic states of solute molecules is, therefore, of substantial importance in photodynamic therapy. The difference in the solvation energies of the final and initial states in various solvents is referred to as solvate-chromic shift and is the main experimental evidence for this energy difference (Ghazy et al, 2004). Therefore, the absorption and emission spectra are more informative in this respect as they are related to the energy of relaxed excited state.…”

Section: Enhancing the Efficacy Of Photodynamic Therapymentioning

confidence: 99%

Quenching of singlet oxygen by natural and synthetic antioxidants and assessment of electronic UV/Visible absorption spectra for alleviating or enhancing the efficacy of photodynamic therapy

2016

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Abstract-Photodynamic therapy (PDT) is one of the methods involved in cancer treatment exploiting singlet oxygen as a weapon to kill cancer cells. Singlet oxygen, a bizarre reactive oxygen species as it is not related to electron transfer to O 2 but it is one of the most active intermediate involved in biochemical reactions as it directly reacts with all the major macromolecules like DNA, protein, lipids etc, various photosensitized oxidations and in the photodegradation of dyes and polymers. Recent studies about the usage of antioxidant along with the photo-sensitizer involved in photodynamic therapy have shown concentration-dependent dual behavior like usually it retards the efficacy of PDT but at a higher dose , it actually enhances the damaging effect of PDT. The natural and synthetic antioxidants are being used in our day to day life in order to increase the shelf life of various food ingredients and processed foods. In this paper, we have compared natural and synthetic antioxidants along with the known singlet oxygen quencher (DABCO) in order to understand the quenching potential of singlet oxygen ( 1 O 2 ) which is lowest electronically excited state of molecular oxygen. The singlet oxygen can be artificially generated through various methods such as sunlight, phosphate, ozonides, NaOCl & H 2 O 2 etc. We have studied the mechanisms of selected antioxidants on the bleaching of RNO linked with the energy decay of 1 O 2 produced by the Mallet reaction (H 2 O 2 + HOCl → HCl + H 2 O + 1 O 2 ). β-Carotene, α-Tocopherol, Ascorbic acid and Quercetin exhibited best dosedependent singlet quenching ranging from 92.3 to 56.5 % at 100μM among others. Overall singlet oxygen is a major concern of light-related properties so we have analyzed the theoretical aspect of electronic UV/visible absorption spectra of the antioxidants studied through ZINDO CI semi-empirical Hamiltonian method. We have compared only the first singlet state of molecules in order to understand whether the structure of the molecules has any influence on the quenching potential. Considering the main features associated with singlet states, we have seen a drastic correlation between known sensitizer of singlet oxygen, i.e. Rose Bengal and DABCO, known scavenger of singlet oxygen in terms of energy and wavelength. This study is important as it highlights the behavior of antioxidant which can improve the effects of photosensitizer used in photodynamic therapy.

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Experimental studies on the determination of the dipole moments of some different laser dyes

Cited by 60 publications

References 20 publications

Photophysical properties and estimation of ground and excited state dipole moments of 7-diethylamino and 7-diethylamino-4-methyl coumarin dyes from absorption and emission spectra

Photophysical properties and estimation of ground and excited state dipole moments of 7-diethylamino and 7-diethylamino-4-methyl coumarin dyes from absorption and emission spectra

Photophysical Parameters, Excitation Energy Transfer, and Photoreactivity of 1,4-Bis(5-phenyl-2-oxazolyl)benzene (POPOP) Laser Dye

Quenching of singlet oxygen by natural and synthetic antioxidants and assessment of electronic UV/Visible absorption spectra for alleviating or enhancing the efficacy of photodynamic therapy

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