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.

scholarly journals Photoactivated cell-killing amino-based flavylium compounds

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hélder Oliveira ◽  
Paula Araújo ◽  
Ana Rita Pereira ◽  
Nuno Mateus ◽  
Victor de Freitas ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Singlet Oxygen ◽  
White Light ◽  
Structural Features ◽  
Cellular Damage ◽  
Quantum Yields ◽  
Type I ◽  
Fluorescence Quantum Yields ◽  
Skin Cells ◽  
Structure Activity

AbstractPhotodynamic therapy (PDT) is a well-established therapeutic for the treatment of different diseases. The growing interest of this technique required the development of new photosensitizers with better photo-features. This work reports the study of the potential of five nature-inspired amino-based flavylium compounds with different structural features as photosensitizers towards topical PDT. In terms of dark cytotoxicity the five pigments were tested towards confluent skin cells in both fibroblasts and keratinocytes. In the range of concentrations tested (6.3–100 μM), keratinocytes were more prone to growth inhibition and the IC50 values for 5OH4′NMe2, 7NEt2st4′NMe2 and 7NEt24′NH2 were determined to be 47.3 ± 0.3 μM; 91.0 ± 0.8 μM and 29.8 ± 0.8 μM, respectively. 7NEt24′NMe2, 7NEt2st4′NMe2 and 7NEt24′NH2 showed significant fluorescence quantum yields (from 3.40 to 20.20%) and production of singlet oxygen (1O2). These latter chromophores presented IC50 values of growth inhibition of keratinocytes between 0.9 and 1.5 µM, after 10 min of photoactivation with white light. This cellular damage in keratinocyte cells upon white light activation was accompanied with the production of reactive oxygen species (ROS). It was also found that the compounds can induce damage by either type I (ROS production) or type II (singlet oxygen) PDT mechanism, although a higher cell survival was observed in the presence of 1O2 quenchers. Overall, a structure–activity relationship could be established, ranking the most important functional groups for the photoactivation efficiency as follows: C7-diethylamino > C4′-dimethylamino > C2-styryl.

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).

Ground- and Excited-State Absorption Spectra of 9-Acetoxy-10(4´-Acetoxy)phenylanthracenes

1986 ◽  
Vol 41 (10) ◽  
pp. 1200-1209
Author(s):  
Janina R. Heldt
Keyword(s):  
Mirror Symmetry ◽  
Energy Levels ◽  
Bathochromic Shift ◽  
Heavy Atom ◽  
Excited State Absorption ◽  
Spectroscopic Properties ◽  
Quantum Yields ◽  
Fluorescence Quantum Yields ◽  
Ring Molecules ◽  
Meso Position

The ground-(S0) and excited -(S1 and T1) state spectra of seven derivatives o f 9-acetoxy- 10(4´-acetoxy)phenylanthracene were determined in the region 50000 - 15000 cm -1 (200 - 660 nm). Comparison of these spectra to the unsubstituted molecule (anthracene) indicates the presence o f bathochromic shift and the steric effect. The substituents cause changes of positions of the energy levels (bigger shifts are noticed for low lying states) and also changes of the absorption intensities of some transitions. The steric hindrances between the phenyl-substituents and the anthracene skeleton are more pronounced if the - OAc(- Me) group or a heavy atom is introduced at position 2´o f the phenyl ring. Molecules possessing such substituents at the meso-position exhibit spectroscopic properties characteristic for a plane molecule in the S0 and S1 states; they show a better preservation of the mirror symmetry between the absorption and fluorescence spectra, lower Stokes shifts and the destabilization energies and bigger fluorescence quantum yields.

scholarly journals Abnormally aggregation-induced emissions observed from hydrogen- and silyl-substituted siloles

2020 ◽  
Vol 43 (1) ◽  
pp. 125-131
Author(s):  
Zhengang Han ◽  
Kefeng Xie
Keyword(s):  
Hydrogen Atom ◽  
Theoretical Calculations ◽  
Quantum Yields ◽  
Aggregation Induced Emission ◽  
Fluorescence Quantum Yields ◽  
High Fluorescence ◽  
First Time

AbstractSilacyclopentadienes (siloles) are currently of great interest because of their intriguing aggregation-induced emission (AIE) characteristics. In this work, abnormally AIE phenomena were observed from silyl- and hydrogen-substituted siloles respectively. We propose silyl-substituent and hydrogen atom effects to explain this via both experiments and theoretical calculations. It was discovered that trimethylsilyl substituents destroyed the p-interactions with the silole core and resulted in the non-fluorescence. Additionally, 1-chloro-1-H-2,3,4,5-tetraphenylsilole featuring strong fluorescences in both solid and solution states with high fluorescence quantum yields represents a new potential photoelectric material. This work not only reports the silole with strong fluorescences in both solid and solution states for the first time but also contributs to enrich the AIE research of siloles.

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.

Phosphorus as a carbon copy and as a photocopy: New conjugated materials featuring multiply bonded phosphorus

2013 ◽  
Vol 85 (4) ◽  
pp. 801-815 ◽  
Author(s):  
M. Cather Simpson ◽  
John D. Protasiewicz
Keyword(s):  
Structural Features ◽  
Main Group ◽  
Quantum Yields ◽  
Conjugated Materials ◽  
Fluorescence Quantum Yields ◽  
Multiply Bonded ◽  
Carbon Copy

Phosphaalkenes (RP=CR2) and diphosphenes (RP=PR) are main group analogues of alkenes (R2C=CR2). Molecules featuring such multiply bonded phosphorus functionalities often display structural features and chemical reactivities that mimic their purely organic counterparts, lending credence to the claim that these compounds are “carbon copies”. We have been expanding this analogy to include oligomers and polymers with extended conjugation that directly involve P=C and P=P units. Many of these materials, however, display little or no photoluminescence (PL). This article summarizes our efforts to understand P=C and P=P photobehavior and to produce materials having significant PL that mimic or “photocopy” the PL properties of the phosphorus-free systems. Recent materials based on benzoxaphospholes (BOPs), benzobisoxaphospholes (BBOPs), and higher analogues having significant fluorescence quantum yields are covered.

Vibrational dependence of electronic nonradiative processes in the state of and

1984 ◽  
Vol 62 (12) ◽  
pp. 1361-1368 ◽  
Author(s):  
D. Winkoun ◽  
D. Chapoulard ◽  
G. Dujardin ◽  
S. Leach
Keyword(s):  
Vibrational Mode ◽  
Spectroscopic Properties ◽  
Quantum Yields ◽  
Electronic Relaxation ◽  
Matrix Elements ◽  
Relaxation Rates ◽  
Fluorescence Quantum Yields ◽  
Fluorescence Photon ◽  
Mode Selectivity ◽  
Nonradiative Processes

Vibrational mode selective, radiationless transitions have been sought in the [Formula: see text] states of [Formula: see text] and [Formula: see text] by determining the radiative kr(ν′) and nonradiative knr(ν′) rates of electronic relaxation of energy selected vibronic levels of these cations. The relaxation rates were derived from measurements of ion fluorescence quantum yields and lifetimes using a photoelectron-fluorescence photon delayed coincidence apparatus, described in the text, in which the ions are formed by direct photoionization. Mode selective behavior is confirmed for the ν1 and ν2 modes of the [Formula: see text] state of [Formula: see text], previously studied by a threshold photoelectron-fluorescence photon coincidence method in which photoion formation involved auto-ionization as well as direct photoionization. In the case of the ν3 and ν4 modes of [Formula: see text], knr(ν′) was found to depend only on the excess energy Eν′ in the [Formula: see text] state and not on the particular mode optically excited. The absence of mode selectivity in this cation could be due to very rapid vibrational redistribution, but more probably results from similar-valued nonradiative coupling matrix elements of vibronic levels involving ν3 and (or) ν4 modes for a given value of Eν′. This is shown to be consistent with the known spectroscopic properties of [Formula: see text].

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.

meso-(2-Benzimidazolyl)-substituted BODIPYs: Synthesis, structures and spectroscopic properties

2020 ◽  
Vol 24 (01n03) ◽  
pp. 230-237
Author(s):  
Hu Gao ◽  
Chenhong Li ◽  
Zhen Shen
Keyword(s):  
Quantum Yield ◽  
Spectroscopic Properties ◽  
Crystallographic Analysis ◽  
Membered Ring ◽  
Quantum Yields ◽  
Fluorescence Quantum Yields ◽  
Nir Dyes ◽  
Nir Fluorescence ◽  
Yield Formula ◽  
Post Modification

A series of meso-(2-benzimidazolyl)-substituted boron dipyrromethene (BODIPY) derivatives 3a–3c and 4 have been synthesized and characterized. The absorption and fluorescence bands of 3a are bathochromically shifted by 36 nm and 61 nm, respectively, compared with those of the meso-phenyl BODIPY in toluene. More importantly, the fluorescence quantum yields of these meso-(2-benzimidazolyl)-substituted BODIPYs (up to 0.45 in toluene) are much higher than those of the previously reported meso-heterocyclic BODIPYs. X-ray crystallographic analysis of the single crystal structure of 3a revealed that the dihedral angle of meso-benzimidazolyl ring and indacene plane (40.47[Formula: see text] ) is smaller compared with that of the meso-tolyl substituted BODIPY (61.4[Formula: see text] ). Replacement of the six-membered ring with a five-membered ring, as well as the absence of hydrogen at the imino-nitrogen, generated the reduced repulsion and the hydrogen bonding interaction. The increased planarity not only provided the substantial delocalization of [Formula: see text] electrons and red shifted the absorption and emission bands but also enhanced the fluorescence quantum yield by reducing free rotation induced nonradiative deactivation pathway. Furthermore, 3,5-distyryl coupled BODIPY 4 exhibits a NIR fluorescence band at 712 nm with moderate quantum yield ([Formula: see text] [Formula: see text] 0.3) in nonpolar and polar solvents, which indicate that meso-(2-benzimidazolyl) BODIPY acts as a good candidate for post modification toward NIR dyes for biological applications.

scholarly journals Synthesis and properties of 5,10,15,20-tetra[4-(3,5-dioctoxybenzamidephenyl] porphyrin and its metal complexes

2012 ◽  
Vol 77 (3) ◽  
pp. 335-348 ◽  
Author(s):  
Wenhui Lian ◽  
Yuanyuan Sun ◽  
Binbin Wang ◽  
Ning Shan ◽  
Tongshun Shi
Keyword(s):  
Metal Complexes ◽  
Raman Spectra ◽  
Metal Ion ◽  
Spectroscopic Properties ◽  
Molecular Structures ◽  
Photoelectron Spectra ◽  
Quantum Yields ◽  
Xps Spectra ◽  
Fluorescence Quantum Yields ◽  
Porphyrin Ligand

A novel 5,10,15,20-tetra[4-(3,5-dioctoxybenzamide)phenyl]porphyrin and its transition metal complexes are reported in this paper. Their molecular structures were characterized by elemental analysis, IR spectra, 1HNMR spectra and UV-Vis spectra. Their spectroscopic properties were studied by Raman spectra, fluorescence spectra and X-ray photoelectron spectra (XPS). The fluorescence quantum yields have been measured at room temperature. The fluorescence intensity of porphyrin ligand was stronger than that of the complexes. In Raman spectra, there was much difference between porphyrin ligand and its metal complexes due to changes of the symmetry of porphyrin plane. In the XPS spectra, the replacement of the free-base protons by a metal ion to form the metalloporphyrin increases the symmetry of the molecule also introduces an electron with-drawing group into the center of the porphyrin ligand which increases the N1s binding energy.

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