scholarly journals Free Rotor Styrylcyanine Chromogens

1986 ◽  
Vol 6 (6) ◽  
pp. 381-389 ◽  
Author(s):  
M. M. Habashy ◽  
M. S. Antonious ◽  
M. Abdel-Kader ◽  
M. S. A. Abdel-Mottaleb
Keyword(s):  
Radiative Decay ◽  
Decay Channel ◽  
Stokes Shift ◽  
Solvent Polarity ◽  
Quantum Yields ◽  
Excitation Wavelength ◽  
Charge Densities ◽  
Fluorescence Quantum Yields ◽  
Organized Assemblies ◽  
Sensitive Function

Fluorescence spectra (maximum wavelength λF) and fluorescence quantum yields (φF) were measured for four structurally related styrylcyanine chromogens of the pyridinium and quinolinium type (1–4) in different solvents at ambient temperature and 77 K. The response of λF and φF values to changes in solvent polarity, solvent hydrogen bonding donor strength, viscosity and temperature was a sensitive function of chromogen structure. The sensitivities of the λF and φF values correlate with the degree of charge transfer character of the S1,CT state; Stokes shift of fluorescence was progressively decreased while φF value was enhanced as the CT character of S1,CT state increases. Moreover, a large edge-excitation red shift was observed in ethanol glass at 77 K. The dominant photophysical features for these dyes are discussed in terms of strong emission from an intramolecular CT state characterized by different solvation sites indicated by the observation of the excitation-wavelength dependent phenomenon in ethanol at 77 K and an important non-radiative decay channel involving rotation of the different parts of molecules leading to a more relaxed weakly fluorescent S1,CT created in fluid media. The viscosity dependence of fluorescence properties (a marked increase in φF was observed with increasing viscosity) suggests that these dyes can be useful reporters of microviscosity for different sites in various organized assemblies. Moreover, it was suggested that increasing H-bonding donor strength of the solvent activates a rotatory non-radiative decay channel probably by localizing charge densities and decreasing CT nature of the S1,CT state.

scholarly journals Inverted energy gap law for the nonradiative decay in fluorescent floppy molecules: larger fluorescence quantum yields for smaller energy gaps

2019 ◽  
Vol 6 (12) ◽  
pp. 1948-1954 ◽  
Author(s):  
Junqing Shi ◽  
Maria A. Izquierdo ◽  
Sangyoon Oh ◽  
Soo Young Park ◽  
Begoña Milián-Medina ◽  
...  
Keyword(s):  
Radiative Decay ◽  
Energy Gap ◽  
Quantum Yields ◽  
Nonradiative Decay ◽  
Fluorescence Quantum Yields ◽  
Energy Gaps ◽  
Energy Gap Law ◽  
Solution Increase ◽  
Floppy Molecules ◽  
Franck Condon

The non-radiative decay of substituted dicyano-distyrylbenzenes in solution increase with the Franck–Condon energy, being opposite to the conventional energy gap law.

scholarly journals Effect of the Substitution Position on the Electronic and Solvatochromic Properties of Isocyanoaminonaphthalene (ICAN) Fluorophores

Molecules ◽  
2019 ◽  
Vol 24 (13) ◽  
pp. 2434 ◽  
Author(s):  
Sándor Lajos Kovács ◽  
Miklós Nagy ◽  
Péter Pál Fehér ◽  
Miklós Zsuga ◽  
Sándor Kéki
Keyword(s):  
Radiative Decay ◽  
Fluorescence Emission ◽  
Solvent Polarity ◽  
Decay Rates ◽  
Quantum Yields ◽  
Time Resolved Fluorescence ◽  
Solvatochromic Shift ◽  
Fluorescence Emission Spectra ◽  
Time Resolved ◽  
Donor And Acceptor

The properties of 1,4-isocyanoaminonaphthalene (1,4-ICAN) and 2,6-isocyanoaminonaphthalene (2,6-ICAN) isomers are discussed in comparison with those of 1,5-isocyanoaminonaphthalene (1,5-ICAN), which exhibits a large positive solvatochromic shift similar to that of Prodan. In these isocyanoaminonaphthalene derivatives, the isocyano and the amine group serve as the donor and acceptor moieties, respectively. It was found that the positions of the donor and the acceptor groups in these naphthalene derivatives greatly influence the Stokes and solvatochromic shifts, which decrease in the following order: 1,5-ICAN > 2,6-ICAN > 1,4-ICAN. According to high-level quantum chemical calculations, this order is well correlated with the charge transfer character of these compounds upon excitation. Furthermore, unlike 1,5-ICAN, the 1,4-ICAN and 2,6-ICAN isomers showed relatively high quantum yields in water, that were determined to be 0.62 and 0.21, respectively. In addition, time-resolved fluorescence experiments revealed that both the radiative and non-radiative decay rates for these three ICAN isomers varied unusually with the solvent polarity parameter ET(30). The explanations of the influence of the solvent polarity on the resulting steady-state and time-resolved fluorescence emission spectra are also discussed.

The influence of phenylethynyl linkers on the photo-physical properties of metal-free porphyrins

2000 ◽  
Vol 04 (07) ◽  
pp. 669-683 ◽  
Author(s):  
GARY A. BAKER ◽  
FRANK V. BRIGHT ◽  
MICHAEL R. DETTY ◽  
SIDDHARTH PANDEY ◽  
COREY E. STILTS ◽  
...  
Keyword(s):  
Excited State ◽  
Radiative Decay ◽  
Phenyl Group ◽  
Quantum Yields ◽  
Fluorescence Lifetimes ◽  
Strongly Coupled ◽  
Metal Free ◽  
Fluorescence Quantum Yields ◽  
Porphyrin Core ◽  
Absorbance Spectra

Series of 5,10,15,20-tetraarylporphyrins 1 and 5,10,15,20-tetrakis[4-(arylethynyl)phenyl]porphyrins 2 were prepared via condensation of pyrrole with the appropriate benzaldehyde or 4-(arylethynyl)benzaldehyde derivative (3). Condensation of meso-phenyldipyrromethane with mixtures of benzaldehyde and 4-(trimethylsilyl-ethynyl)benzaldehyde gave a separable mixture of mono- (6), bis- (both cis-7 and trans-8) and tris[4-(trimethylsilylethynyl)phenyl]porphyrin (9). Following removal of the trimethylsilyl groups of 6–9, the 4-ethynylphenyl groups of 11–14 were coupled to 1-iodo-3,5-di(trifluoromethyl)benzene with Pd ( OAc )2 to give 15–18 bearing one, two (both cis- and trans-) and three 4-[bis-3,5-(trifluoromethyl)phenylethynyl]phenyl groups respectively. Coupling of 11 and 1-iodo-4-nitrobenzene with Pd ( OAc )2 gave porphyrin 19 with one 4-(4-nitrophenylethynyl)phenyl group. Porphyrin 24 with a p-quinone linked to the porphyrin core via a phenylethynyl group was prepared via similar chemistry. The absorbance spectra, emission maxima, excited-state fluorescence lifetimes, quantum yields of fluorescence, rates of fluorescence and rates of non-radiative decay were measured for each of the porphyrins. Absorbance spectra and emission maxima were nearly identical for all the porphyrins of this study, which suggests that the aryl groups and 4-(arylethynyl)phenyl groups are not strongly coupled to the porphyrin core in these metal-free compounds. Fluorescence quantum yields and rates of radiative decay were larger for porphyrins bearing 4-(arylethynyl)phenyl groups, while excited-state fluorescence lifetimes were somewhat shorter. These effects were additive for each additional 4-(arylethynyl)phenyl group.

A bright red-emitting flavonoid for Al3+ detection in live cells without quenching ICT fluorescence

2019 ◽  
Vol 55 (49) ◽  
pp. 7041-7044 ◽  
Author(s):  
Chathura S. Abeywickrama ◽  
Keti A. Bertman ◽  
Yi Pang
Keyword(s):  
Stokes Shift ◽  
Live Cells ◽  
Quantum Yields ◽  
Large Stokes Shift ◽  
Fluorescence Quantum Yields ◽  
High Fluorescence

A bright red-emitting flavonoid derivative was synthesized, which exhibited a large Stokes shift (Δλ > 150 nm) and high fluorescence quantum yields (ϕfl = 0.10–0.35).

scholarly journals Theoretical and Experimental Investigations of Large Stokes Shift Fluorophores Based on a Quinoline Scaffold

Molecules ◽  
2020 ◽  
Vol 25 (11) ◽  
pp. 2488
Author(s):  
Barbara Czaplińska ◽  
Katarzyna Malarz ◽  
Anna Mrozek-Wilczkiewicz ◽  
Aneta Slodek ◽  
Mateusz Korzec ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Stokes Shift ◽  
Visible Region ◽  
Spectroscopic Properties ◽  
Cellular Membrane ◽  
Structural Features ◽  
Quantum Yields ◽  
Experimental Investigations ◽  
Case Scenario ◽  
Fluorescence Quantum Yields

A series of novel styrylquinolines with the benzylidene imine moiety were synthesized and spectroscopically characterized for their applicability in cellular staining. The spectroscopic study revealed absorption in the ultraviolet–visible region (360–380 nm) and emission that covered the blue-green range of the light (above 500 nm). The fluorescence quantum yields were also determined, which amounted to 0.079 in the best-case scenario. The structural features that are behind these values are also discussed. An analysis of the spectroscopic properties and the theoretical calculations indicated the charge-transfer character of an emission, which was additionally evaluated using the Lippert–Mataga equation. Changes in geometry in the ground and excited states, which had a significant influence on the emission process, are also discussed. Additionally, the capability of the newly synthesized compounds for cellular staining was also investigated. These small molecules could effectively penetrate through the cellular membrane. Analyses of the images that were obtained with several of the tested styrylquinolines indicated their accumulation in organelles such as the mitochondria and the endoplasmic reticulum.

Fluorescence Quantum Yields of Laser Dyes Determined by On-Line Computer Evaluation

1982 ◽  
Vol 37 (3) ◽  
pp. 219-223 ◽  
Author(s):  
Günter Gauglitz ◽  
Alwin Lorch ◽  
Dieter Oelkrug
Keyword(s):  
Dark Current ◽  
Optimal Choice ◽  
Quantum Yields ◽  
Excitation Wavelength ◽  
Laser Dyes ◽  
Correction Procedure ◽  
Fluorescence Quantum Yields ◽  
On Line ◽  
Better Than

Abstract The determination of relative fluorescence quantum yields has been improved to better than 3% precision by use of a multichannel analyzer and an on-line desk-top computer. The new combined device for data acquisition and handling as well as a new correction procedure are described. Drifts of excitation source and dark current can be omitted. The yields for laser dyes, emitting at short wavelengths, are presented in dependence on excitation wavelength. These results simplify the optimal choice of the pump conditions of laser dyes, which usually are not photostable.

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.

scholarly journals Remarkable Increase of Fluorescence Quantum Efficiency by Cyano Substitution on an ESIPT Molecule 2-(2-Hydroxyphenyl)benzothiazole: A Highly Photoluminescent Liquid Crystal Dopant

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1105
Author(s):  
Tsuneaki Sakurai ◽  
Masaya Kobayashi ◽  
Hiroyuki Yoshida ◽  
Masaki Shimizu
Keyword(s):  
Liquid Crystal ◽  
Excited State ◽  
Solid State ◽  
Room Temperature ◽  
Cyano Group ◽  
Stokes Shift ◽  
Phenyl Group ◽  
Intramolecular Proton Transfer ◽  
Quantum Yields ◽  
Fluorescence Quantum Yields

Fluorescent molecules with excited-state intramolecular proton transfer (ESIPT) character allow the efficient solid-state luminescence with large Stokes shift that is important for various applications, such as organic electronics, photonics, and bio-imaging fields. However, the lower fluorescence quantum yields (ΦFL) in the solution or viscous media, due to their structural relaxations in the excited state to reach the S0/S1 conical intersection, shackle further applications of ESIPT-active luminophores. Here we report that the introduction of a cyano group (-CN) into the phenyl group of 2-(2-hydroxyphenyl)benzothiazole (HBT), a representative ESIPT compound, remarkably increase its fluorescence quantum yield (ΦFL) from 0.01 (without -CN) to 0.49 (with -CN) in CH2Cl2, without disturbing its high ΦFL (=0.52) in the solid state. The large increase of the solution-state ΦFL of the cyano-substituted HBT (CN-HBT) is remarkable, comparing with our previously reported ΦFL values of 0.05 (with 4-pentylphenyl), 0.07 (with 1-hexynyl), and 0.15 (with 4-pentylphenylethynyl). Of interest, the newly-synthesized compound, CN-HBT, is miscible in a conventional room-temperature nematic liquid crystal (LC), 4-pentyl-4′-cyano biphenyl (5CB), up to 1 wt% (~1 mol%), and exhibits a large ΦFL of 0.57 in the viscous LC medium. A similar ΦFL value of ΦFL = 0.53 was also recorded in another room-temperature LC, trans-4-(4-pentylcyclohexyl)benzonitrile (PCH5), with a doping ratio of 0.5 wt% (~0.5 mol%). These 5CB/CN-HBT and PCH5/CN-HBT mixtures serve as light-emitting room-temperature LCs, and show anisotropic fluorescence with the dichroic ratio of 3.1 upon polarized excitation, as well as electric field response of luminescence intensity changes.

Fluorescence behaviour of some 4-substituted halobenzenes

1985 ◽  
Vol 50 (8) ◽  
pp. 1753-1763 ◽  
Author(s):  
Bohumír Koutek ◽  
Lubomír Musil ◽  
Jiří Velek ◽  
Milan Souček
Keyword(s):  
Decay Rate ◽  
Radiative Decay ◽  
Mean Value ◽  
Quantum Yields ◽  
Intersystem Crossing ◽  
Radiative Decay Rate ◽  
Fluorescence Quantum Yields ◽  
Band Position ◽  
Fluorescence Characteristics ◽  
Acetonitrile Solutions

The fluorescence characteristics of 4-substituted chloro and fluorobenzenes I and II were studied in isooctane and acetonitrile solutions. It was found that all compounds exhibit a weak (substituent and solvent dependent) fluorescence in the range 305-370 nm with quantum yields 1.2 . 10-2-2.3 . 10-1. The relation between the substituent nature and fluorescence band position may be quantified by log νf~ = ρσp + log νf~0, the magnitude of the shift paralleling the donor strength of the substituent. Fluorescence quantum yields are increased approximately by a factor 2 on going from isooctane to acetonitrile and solvent-induced shifts are proportional to the static dipole moment change Δμ which occurs upon excitation. Radiative decay rate varies only slightly around a mean value of 5 . 107 s-1 and shows no substantial difference between chloro (I) and fluoro (II) derivatives. The non-radiative decay rate (of the order ~ 109 s-1) was found to be about 5 times higher in the case of chloro compounds due to the more efficient S1 - Tn intersystem crossing.

Photophysical and Photochemical Properties of 2,3-Dihydro-4(l H)-quinolinones. Part I. Fluorescence Properties

1990 ◽  
Vol 45 (9-10) ◽  
pp. 980-986 ◽  
Author(s):  
Sn. Bakalova ◽  
L. Biczók ◽  
I. Kavrakova ◽  
T. Bérces
Keyword(s):  
Excited States ◽  
Room Temperature ◽  
Solvent Polarity ◽  
Fluorescence Decay ◽  
Fluorescence Properties ◽  
Quantum Yields ◽  
Fluorescence Quantum Yields ◽  
Decay Times ◽  
Photochemical Properties ◽  
Fluorescence Decay Times

Abstract Absorption spectra and fluorescence properties of 2,3-dihydro-4(1 H)-quinolinone derivatives were studied at room temperature in different solvents. It has been found that the fluorescence quantum yields and fluorescence decay times strongly depend on the molecular structure and solvent polarity. The character and the energy of excited states were determined by PPP and CNDO/S quantum-chemical calculations.

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