scholarly journals Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases

2021 ◽  
Vol 17 ◽  
pp. 2799-2811
Author(s):  
Inaiá O Rocha ◽  
Yuri G Kappenberg ◽  
Wilian C Rosa ◽  
Clarissa P Frizzo ◽  
Nilo Zanatta ◽  
...  
Keyword(s):  
Schiff Bases ◽  
Fluorescence Yield ◽  
Good Stability ◽  
Ros Generation ◽  
White Led ◽  
Polar Solvents ◽  
Alkyl Aryl ◽  
Yield Values ◽  
Stokes Shifts ◽  
Led Irradiation

A new series of ten examples of Schiff bases, namely (E)-2-(((2-alkyl(aryl/heteroaryl)-4-(trifluoromethyl)quinolin-6-yl)imino)methyl)phenols 3, was easily synthesized with yields of up to 91% from the reactions involving a series of 2-(R-substituted) 6-amino-4-(trifluoromethyl)quinolines 1 and 4(5)-R1-substituted salicylaldehydes 2 – in which alkyl/aryl/heteroaryl for 2-R-substituents are Me, Ph, 4-MeC6H4, 4-FC6H4, 4-NO2C6H4, and 2-furyl, and R1-substituents are 5-NEt2, 5-OCH3, 4-Br, and 4-NO2. Complementarily, the Schiff bases showed low to good quantum fluorescence yield values in CHCl3 (Φf = 0.12–0.80), DMSO (Φf = 0.20–0.75) and MeOH (Φf = 0.13–0.85). Higher values of Stokes shifts (SS) were observed in more polar solvents (DMSO; 65–150 nm and MeOH; 65–130 nm) than in CHCl3 (59–85 nm). Compounds 3 presented good stability under white-LED irradiation conditions and moderate ROS generation properties were observed.

scholarly journals Photophysical, photostability, and ROS generation properties of new trifluoromethylated quinoline-phenol Schiff bases

2021 ◽  
Author(s):  
Inaiá O Rocha ◽  
Yuri G Kappenberg ◽  
Wilian C Rosa ◽  
Clarissa P Frizzo ◽  
Nilo Zanatta ◽  
...  
Keyword(s):  
Schiff Bases ◽  
Fluorescence Yield ◽  
Good Stability ◽  
Ros Generation ◽  
White Led ◽  
Polar Solvents ◽  
Alkyl Aryl ◽  
Yield Values ◽  
Stokes Shifts ◽  
Led Irradiation

A new series of ten examples of (E)-2-(((2-alkyl(aryl/heteroaryl)-4-(trifluoromethyl)quinolin-6-yl)imino)methyl)phenols (Schiff bases), was easy synthesized at yields up to 91% from the reactions involving a series of 2-(R-substituted) 6-amino-4-(trifluoromethyl)quinolines and 4(5)-R1-substituted salicylaldehydes – in which alkyl/aryl/heteroaryl for 2-(R)-substituents are Me, Ph, 4-MeC6H4, 4-FC6H4, 4-NO2C6H4, and 2-furyl, and (R1)-substituents are 5-NEt2, 5-OCH3, 4-Br, and 4-NO2. Complementarily, the Schiff bases showed low to good quantum fluorescence yield values both in CHCl3 (Φf = 0.12-0.80), DMSO (Φf = 0.20-0.75) and MeOH (Φf = 0.13-0.85). Higher values of Stokes shifts (SS) ​​were observed in more polar solvents (DMSO; 65-150 nm and MeOH; 65-130 nm) than in CHCl3 (59-85 nm). Also, compounds 3 confirmed to present good stability under white-LED irradiation conditions and moderate ROS generation properties were observed.

Fluorescence of Cyclic Adducts of Fullerene

1994 ◽  
Vol 359 ◽  
Author(s):  
Tsung-I Lin ◽  
Syh-Kun Lin ◽  
Lung-Lin Shiu ◽  
Kuo-Ming Chien ◽  
Tien-Yau Luh
Keyword(s):  
Spectral Properties ◽  
Fluorescence Spectra ◽  
Room Temperature ◽  
Parent Compound ◽  
Molar Absorptivity ◽  
Absorption Bands ◽  
Polar Solvents ◽  
Peak Broadening ◽  
Stokes Shifts ◽  
Cyclic Adducts

ABSTRACTFive cyclic adducts C60C4H6, C60C5H6, C60NHCO2, C60NCO2Et, and C60CHCO2Et have been synthesized and their absorption and fluorescence spectral properties investigated and compared with those of the parent. Breaking the structural symmetry of C60 apparently resulted in enhancing the quantum yield two to three-folds in some adducts and thus made fluorescence much easier to be measured at room temperature. New absorption bands and altered fluorescence spectra were observed in the adducts. The Stokes' shifts of the adducts were small, about 4-5 nrm, compared to 68 nm for the parent compound. All the adducts exhibited a single fluorescence lifetime about the same as C60 (ca. 1.3 ns). Aliphatic solvents had little influence on the absorption or fluorescence spectral profile except on the molar absorptivity whereas aromatic and polar solvents strongly interacted with the adducts causing a peak broadening effect.

K X-ray yields from elements of low atomic number

1963 ◽  
Vol 274 (1358) ◽  
pp. 319-342 ◽  
Keyword(s):  
Electron Beam ◽  
Gas Flow ◽  
Target Surface ◽  
Beryllium Oxide ◽  
Fluorescence Yield ◽  
Quantum Yields ◽  
X Ray ◽  
Yield Values ◽  
Absolute Measurements ◽  
Yield Formula

Absolute measurements have been made of the K X-ray quantum yields resulting from electron bombardment of solid targets, containing the elements beryllium, boron, carbon, oxygen, fluorine and aluminium. Beryllium oxide and lithium fluoride targets were used for the oxygen and fluorine measurements, respectively; targets containing at least 99% of the pure element were used for the remainder. The yield from each target was measured along a path inclined at 45° to the surface and at several electron accelerating voltages in the range 500 to 30 000 V ; the electron beam was then inclined at an angle of 45° to the surface of the target. The carbon yield was also measured at 10° to the surface with the electron beam inclined at 80° to the surface. The gas-flow proportional counter was operated at atmospheric pressure with a nitro-cellulose window; the window used for detecting beryllium and boron radiation was less than 1000 Å thick. The relative variation of the X-ray yield with the electron accelerating voltage is in excellent agreement with Archard’s (1960) predictions for the yield measured both at 45° and 10° to the target surface but with the electron beam normal to the surface. The absolute yield values, apart from those for beryllium, are 5 to 15% higher than those calculated from Archard’s theory and Burhop’s (1952) fluorescence yield formula; the beryllium yield is about half that predicted. For 5 ≤ Z ≤ 9, the greatest X-ray yield at 45° to the target surface is obtained when the accelerating kilovoltage is between 0.5 ( Z — 1) 2 and 0.6 ( Z — 1) 2 and amounts to 9 x 10 13 Z 5/2 photons per incident coulomb per steradian (1.45 x 10 -5 Z photons per incident electron per steradian).

SOLVENT EFFECT ON ABSOLUTE FLUORESCENCE QUANTUM YIELD OF RHODAMINE 6G DETERMINED USING TRANSIENT THERMAL LENS TECHNIQUE

1999 ◽  
Vol 13 (16) ◽  
pp. 563-576 ◽  
Author(s):  
C. V. BINDHU ◽  
S. S. HARILAL ◽  
V. P. N. NAMPOORI ◽  
C. P. G. VALLABHAN
Keyword(s):  
Quantum Yield ◽  
Thermal Lens ◽  
Fluorescence Quantum Yield ◽  
Rhodamine 6G ◽  
Excited State Absorption ◽  
Fluorescence Yield ◽  
Dual Beam ◽  
Yield Values ◽  
Transient Thermal ◽  
Absolute Fluorescence

Dual beam thermal lens technique is successfully employed for the determination of absolute fluorescence quantum yield of rhodamine 6G laser dye in different solvents. A 532 nm radiation from a Q-switched Nd:YAG laser was used for the excitation purpose. The fluorescence quantum yield values are found to be strongly influenced by environmental effects. It has been observed that fluorescence yield is greater for rhodamine 6G in ethylene glycol system than in water or in methanol. Our results also indicate that parameters like concentration of the dye solution, aggregate formation and excited state absorption affect the absolute values of fluorescence yield significantly.

Unusual high fluorescence of two nitro-distyrylbenzene-like compounds induced by CT processes affecting the fluorescence/intersystem-crossing competition

2015 ◽  
Vol 17 (22) ◽  
pp. 14740-14749 ◽  
Author(s):  
B. Carlotti ◽  
F. Elisei ◽  
U. Mazzucato ◽  
A. Spalletti
Keyword(s):  
Charge Transfer ◽  
Fluorescence Yield ◽  
Intersystem Crossing ◽  
Polar Solvents ◽  
High Fluorescence

Fluorescence/intersystem crossing/photoisomerization competition in the relaxation of nitro-substituted distyrylbenzene-like compounds: charge transfer induced, unusually high, fluorescence yield in polar solvents.

Synthesis and photophysical properties of meso-aryloxy linked BODIPY monomers, dimers, and trimer

2016 ◽  
Vol 20 (01n04) ◽  
pp. 475-489 ◽  
Author(s):  
Changjiang Yu ◽  
Qinghua Wu ◽  
Zhonghua Tian ◽  
Tingting Li ◽  
Erhong Hao ◽  
...  
Keyword(s):  
Photophysical Properties ◽  
Spatial Arrangement ◽  
Nucleophilic Aromatic Substitution ◽  
Quantum Yields ◽  
Aromatic Substitution ◽  
Polar Solvents ◽  
Fluorescence Quantum Yields ◽  
Species Formation ◽  
The Relationship ◽  
Stokes Shifts

A series of meso-aryloxy linked BODIPY monomers, dimers and trimer were synthesized by nucleophilic aromatic substitution (SNAr) reaction from phenols with meso-chloro BODIPY and their photophysical properties were systematically studied by UV-vis and fluorescence spectroscopy. The relationship between their photophysical properties and the spatial arrangement of meso-aryloxy linked BODIPYs has been discussed. The monomers exhibited different extent solvent-dependent fluorescence, and fluorescence quenching in polar solvents were found relative to the HOMO energies of the donor (meso-phenols), indicating possible PET effect from meso-phenols to the BODIPY fluorophore. Ortho-dimer showed unusual broad red-shifted emission bands centered at 550 nm with a larger Stokes shifts at the range of 2900–3400 cm[Formula: see text], and low fluorescence quantum yields, which was in sharp contrast to those of other dimers and trimer, indicating of possible excimeric species formation due to slipped cofacial arrangement ofortho-dimer.

Synthesis and photophysical study of new blue fluorescent poly(azomethine-1,3,4-oxadiazole)s containing dimethylamino groups

2017 ◽  
Vol 30 (3) ◽  
pp. 339-346 ◽  
Author(s):  
Elena Hamciuc ◽  
Mihaela Homocianu ◽  
Corneliu Hamciuc ◽  
Ionela-Daniela Carja
Keyword(s):  
Stokes Shift ◽  
Solvent Polarity ◽  
Decomposition Temperature ◽  
Photoluminescence Spectra ◽  
Polar Solvents ◽  
Initial Decomposition Temperature ◽  
Yield Values ◽  
Photophysical Study ◽  
Hcl Concentration ◽  
Terephthalic Aldehyde

New aromatic polyazomethines were synthesized by polycondensation reaction of a diamine containing 1,3,4-oxadiazole ring, namely, 4,4′-diamino-4″-[2-(4-phenoxy)-5-(4-dimethylaminophenyl)-1,3,4-oxadiazole)]triphenylmethane, with terephthalic aldehyde or bis(4-formylphenoxyphenyl)fluorene, by using N-methyl-2-pyrrolidinone (NMP) as solvent. The polymers were easily soluble in polar solvents, such as NMP, N, N-dimethylacetamide, or chloroform, and showed high thermal stability with the initial decomposition temperature above 415°C and the temperature of 10% weight loss in the range of 450–460°C. They exhibited high char yield at 800°C in the range of 52–56%. Optical properties were studied by absorption and photoluminescence spectra. In solution, the polymers presented two absorption maxima in the ranges 273–278 and 330–346 nm and emitted violet-blue light in the range of 413–468 nm, depending on the solvent polarity. The Stokes shift and emission quantum yield values depend on the polymer structure and solvent polarity. The emission intensity in NMP solution was enhanced upon increasing the HCl concentration, while the absorption spectral profile was slightly influenced.

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