scholarly journals Deciphering the unusual fluorescence in weakly coupled bis-nitro-pyrrolo[3,2-b]pyrroles

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Yevgen M. Poronik ◽  
Glib V. Baryshnikov ◽  
Irena Deperasińska ◽  
Eli M. Espinoza ◽  
John A. Clark ◽  
...  
Keyword(s):  
Fluorescent Dyes ◽  
Solvent Polarity ◽  
Quantum Yields ◽  
Electronic Coupling ◽  
Fluorescence Quantum Yields ◽  
Organic Optoelectronics ◽  
Weakly Coupled ◽  
Nitro Aromatics ◽  
Donor Acceptor ◽  
The Media

AbstractElectron-deficient π-conjugated functional dyes lie at the heart of organic optoelectronics. Adding nitro groups to aromatic compounds usually quenches their fluorescence via inter-system crossing (ISC) or internal conversion (IC). While strong electronic coupling of the nitro groups with the dyes ensures the benefits from these electron-withdrawing substituents, it also leads to fluorescence quenching. Here, we demonstrate how such electronic coupling affects the photophysics of acceptor–donor–acceptor fluorescent dyes, with nitrophenyl acceptors and a pyrrolo[3,2-b]pyrrole donor. The position of the nitro groups and the donor-acceptor distance strongly affect the fluorescence properties of the bis-nitrotetraphenylpyrrolopyrroles. Concurrently, increasing solvent polarity quenches the emission that recovers upon solidifying the media. Intramolecular charge transfer (CT) and molecular dynamics, therefore, govern the fluorescence of these nitro-aromatics. While balanced donor-acceptor coupling ensures fast radiative deactivation and slow ISC essential for large fluorescence quantum yields, vibronic borrowing accounts for medium dependent IC via back CT. These mechanistic paradigms set important design principles for molecular photonics and electronics.

Viskositätsabhängigkeit der Fluoreszenzquantenausbeute von Donator-Akzeptor-substituierten trans-Stilbenen in unpolaren wenig viskosen Lösungsmitteln

1982 ◽  
Vol 37 (4) ◽  
pp. 383-386
Author(s):  
D. Gloyna ◽  
A. Kawski ◽  
I. Gryczyński
Keyword(s):  
Dynamic Viscosity ◽  
Quantum Yields ◽  
Solvent Interactions ◽  
Fluorescence Quantum Yields ◽  
Donor Acceptor ◽  
Viscosity Dependence

Abstract Fluorescence quantum yields, φf, of donor-acceptor substituted trans-stilbenes, 1, in n-heptane and toluene depend upon the solvent dynamic viscosity η according to the relation ln(φf-1 - 1) = a ln(η-1)+b. By changing the temperature (278 < T < 343 K) the viscosity was varied. The viscosity dependence of φf can be accounted for by a corresponding viscosity depending radiations less deactivation of the S1 state, which in low solutions is first of all determined by the intramolecular donor-acceptor and universal intermolecular solute-solvent interactions, and then by viscosity.

scholarly journals Emission solvatochromic, solid-state and aggregation-induced emissive α-pyrones and emission-tuneable 1H-pyridines by Michael addition–cyclocondensation sequences

2019 ◽  
Vol 15 ◽  
pp. 2684-2703 ◽  
Author(s):  
Natascha Breuer ◽  
Irina Gruber ◽  
Christoph Janiak ◽  
Thomas J J Müller
Keyword(s):  
Solid State ◽  
Michael Addition ◽  
Photophysical Properties ◽  
Ethyl Cyanoacetate ◽  
Product Formation ◽  
Quantum Yields ◽  
Substitution Pattern ◽  
Fluorescence Quantum Yields ◽  
Emission Enhancement ◽  
Donor Acceptor

Starting from substituted alkynones, α-pyrones and/or 1H-pyridines were generated in a Michael addition–cyclocondensation with ethyl cyanoacetate. The peculiar product formation depends on the reaction conditions as well as on the electronic substitution pattern of the alkynone. While electron-donating groups furnish α-pyrones as main products, electron-withdrawing groups predominantly give the corresponding 1H-pyridines. Both heterocycle classes fluoresce in solution and in the solid state. In particular, dimethylamino-substituted α-pyrones, as donor–acceptor systems, display remarkable photophysical properties, such as strongly red-shifted absorption and emission maxima with daylight fluorescence and fluorescence quantum yields up to 99% in solution and around 11% in the solid state, as well as pronounced emission solvatochromism. Also a donor-substituted α-pyrone shows pronounced aggregation-induced emission enhancement.

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 Taming fluorescent dyes with cucurbituril

2005 ◽  
Vol 7 (3) ◽  
pp. 133-141 ◽  
Author(s):  
Werner M. Nau ◽  
Jyotirmayee Mohanty
Keyword(s):  
Fluorescent Dyes ◽  
Thermal Stabilization ◽  
Correlation Spectroscopy ◽  
Cresyl Violet ◽  
Quantum Yields ◽  
Prolonged Storage ◽  
Xanthene Dyes ◽  
Scanning Confocal Microscopy ◽  
Fluorescence Quantum Yields ◽  
Spectral Shifts

The potential of the supramolecular host molecule cucurbit[7]uril to serve as a stabilizing additive and enhancement agent was investigated for the following dyes in aqueous solution: rhodamine 6G, rhodamine 123, tetramethylrhodamine, cresyl violet, fluorescein, coumarin 102, pyronin B, pyronin Y, two cyanine 5 and one cyanine 3 derivative, and IR140 as well as IR144. For most cationic dyes photostabilization was established, and a pronounced thermal stabilization due to deaggregation and solubilization was observed for the xanthene dyes. The advantageous effects are attributed to the formation of inclusion complexes with different photophysical and photochemical properties. The complexation is accompanied by spectral shifts characteristic for the inclusion in a less polar environment, while the fluorescence quantum yields as well as the brightness show an increase, with few exceptions. As a consequence of the low polarizability inside the cucurbituril cavity, the fluorescence lifetimes of the included dyes increase substantially and systematically. Applications of the new photostabilizing additive for dye lasers, for prolonged storage of dye solutions, in scanning confocal microscopy, and fluorescence correlation spectroscopy are discussed.

Effect of Substituents on the Viscosity Dependence of Fluorescence and on the S1 - T1 Energy Gap of Donor-Acceptor Substituted Trans-Stilbenes

1997 ◽  
Vol 52 (12) ◽  
pp. 837-842 ◽  
Author(s):  
Hans E. Wilhelm ◽  
Horst Gebert ◽  
Wolfgang Regenstein
Keyword(s):  
Energy Gap ◽  
Quantum Yields ◽  
Intersystem Crossing ◽  
Triplet Energy ◽  
Fluorescence Quantum Yields ◽  
Donor Acceptor ◽  
Fluorescence And Phosphorescence Spectra ◽  
Viscosity Dependence ◽  
Fluorescence And Phosphorescence ◽  
Phosphorescence Spectra

The dependence of fluorescence quantum yields and S1-lifetimes of donor-acceptor substituted trans-stilbenes on temperature was measured in the temperature range from 298 to 100 K, using solutions of stilbenes in 3-methylpentane (3-MP). Measurements of fluorescence and phosphorescence spectra show that the triplet energy is almost independent of the acceptor. The S1-energy and the S1-T1 energy gap decrease with increasing acceptor strength. For all compounds intersystem crossing (ISC) S1 → T1, is negligible

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.

The effects of spacer length on the fluorescence quantum yields of the benzofurazan compounds bearing a donor-acceptor system

Luminescence ◽  
2002 ◽  
Vol 17 (1) ◽  
pp. 11-14 ◽  
Author(s):  
Maki Onoda ◽  
Seiichi Uchiyama ◽  
Tomofumi Santa ◽  
Kazuhiro Imai
Keyword(s):  
Quantum Yields ◽  
Spacer Length ◽  
Fluorescence Quantum Yields ◽  
Donor Acceptor

scholarly journals Excited-state relaxation of some aminoquinolines

2006 ◽  
Vol 2006 ◽  
pp. 1-6 ◽  
Author(s):  
M. N. Khimich ◽  
B. M. Uzhinov
Keyword(s):  
Excited State ◽  
Fluorescence Spectra ◽  
Solvent Polarity ◽  
Quantum Yields ◽  
Absorption And Fluorescence Spectra ◽  
Molecular Fragments ◽  
Orientational Relaxation ◽  
Solvent Viscosity ◽  
Fluorescence Quantum Yields ◽  
Different Temperatures

The absorption and fluorescence spectra, fluorescence quantum yields and lifetimes, and fluorescence rate constants (kf) of 2-amino-3-(2′-benzoxazolyl)quinoline (I), 2-amino-3-(2′-benzothiazolyl)quinoline (II), 2-amino-3-(2′-methoxybenzothiazolyl)-quinoline (III), 2-amino-3-(2′-benzothiazolyl)benzoquinoline (IV) at different temperatures have been measured. The shortwavelength shift of fluorescence spectra of compounds studied (23–49 nm in ethanol) as the temperature decreases (the solvent viscosity increases) points out that the excited-state relaxation process takes place. The rate of this process depends essentially on the solvent viscosity, but not the solvent polarity. The essential increasing of fluorescence rate constantkf(up to about 7 times) as the solvent viscosity increases proves the existence of excited-state structural relaxation consisting in the mutual internal rotation of molecular fragments of aminoquinolines studied, followed by the solvent orientational relaxation.

Sign in / Sign up

Export Citation Format

Share Document