scholarly journals Аннигиляционная замедленная флуоресценция индола и карбазола в жидких растворах при комнатной температуре

2019 ◽  
Vol 126 (2) ◽  
pp. 141
Author(s):  
А.А. Суходола
Keyword(s):  
Ground State ◽  
Fluorescence Spectra ◽  
Dipole Interaction ◽  
Delayed Fluorescence ◽  
The Self ◽  
Triplet States ◽  
Excited Singlet ◽  
Quenching Rate ◽  
Annihilation Delayed Fluorescence ◽  
Quenching Rate Constant

AbstractThe spectra of long-lasting luminescence of indole and carbazole in neutral (cyclohexane) and polar (ethanol) solvents are obtained. The spectra of long-lasting luminescence of indole in these solvents are shifted to longer wavelengths with respect to the fluorescence spectra. The spectra of long-lasting luminescence of carbazole in both solvents coincide with the fluorescence spectra. The long-lasting glow of indole is interpreted as the annihilation delayed fluorescence (ADF) of dimers, while the long-lasting glow of carbazole is attributed to the ADF of monomers. It is suggested that the indole dimers are formed due to the dipole–dipole interaction of molecules in the excited singlet and ground states appearing as a result of the triplet–triplet annihilation. The ADF kinetics is measured, and the lifetimes of the triplet states of indole in cyclohexane are estimated. It is established that the lifetime is determined by quenching of the triplet states by molecules in the ground state. The self-quenching rate constant is found to be 6.2 × 10^7 M^–1 s^–1.

scholarly journals Halogen-Bond Assisted Photoinduced Electron Transfer

Molecules ◽  
2019 ◽  
Vol 24 (23) ◽  
pp. 4361
Author(s):  
Bogdan Dereka ◽  
Ina Fureraj ◽  
Arnulf Rosspeintner ◽  
Eric Vauthey
Keyword(s):  
Electron Transfer ◽  
Excited State ◽  
Ground State ◽  
Halogen Bond ◽  
Quenching Rate ◽  
Excited Complex ◽  
Diffusion Controlled ◽  
Donor Acceptor ◽  
Quenching Rate Constant ◽  
Excited State Population

The formation of a halogen-bond (XB) complex in the excited state was recently reported with a quadrupolar acceptor–donor–acceptor dye in two iodine-based liquids (J. Phys. Chem. Lett. 2017, 8, 3927–3932). The ultrafast decay of this excited complex to the ground state was ascribed to an electron transfer quenching by the XB donors. We examined the mechanism of this process by investigating the quenching dynamics of the dye in the S1 state using the same two iodo-compounds diluted in inert solvents. The results were compared with those obtained with a non-halogenated electron acceptor, fumaronitrile. Whereas quenching by fumaronitrile was found to be diffusion controlled, that by the two XB compounds is slower, despite a larger driving force for electron transfer. A Smoluchowski–Collins–Kimball analysis of the excited-state population decays reveals that both the intrinsic quenching rate constant and the quenching radius are significantly smaller with the XB compounds. These results point to much stronger orientational constraint for quenching with the XB compounds, indicating that electron transfer occurs upon formation of the halogen bond.

A Highly Resolved Yibronic Spectra of Dioxido-p-terphenyl and Trioxido-p-quaterphenyl in n-Hexanc at 77 K

1982 ◽  
Vol 37 (1) ◽  
pp. 91-94
Author(s):  
A. Kawski ◽  
M. Ligȩza
Keyword(s):  
Raman Spectra ◽  
Ground State ◽  
Fluorescence Spectra ◽  
Vibrational Structure ◽  
Ir And Raman Spectra ◽  
Absorption And Fluorescence Spectra ◽  
Excited Singlet ◽  
Ir And Raman ◽  
Good Agreement

Abstract Highly resolved vibronic absorption and fluorescence spectra of dioxido-p-terphenyl and the fluorescence spec-trum of trioxido-p-quaterphenyl in n-hexane at 77 K were obtained. The analysis of the vibrational structure in the excited singlet Si and in the ground So state gives funda-mental frequencies in the ground state in good agreement with those from infrared (IR) and Raman spectra.

scholarly journals Characteristics of the excited triplet states of thiolated guanosine derivatives and singlet oxygen generation

2018 ◽  
Vol 17 (10) ◽  
pp. 1469-1476 ◽  
Author(s):  
Shoma Miyata ◽  
Shunsuke Tanabe ◽  
Tasuku Isozaki ◽  
Yao-Zhong Xu ◽  
Tadashi Suzuki
Keyword(s):  
Singlet Oxygen ◽  
Triplet States ◽  
Quenching Rate ◽  
Singlet Molecular Oxygen ◽  
Excited Triplet ◽  
Oxygen Generation ◽  
Singlet Oxygen Generation ◽  
Oxygen Conditions ◽  
Quenching Rate Constant ◽  
Excited Triplet States

The long intrinsic lifetime and low self-quenching rate constant of the triplet 6,8-dithioguanosine lead to efficient singlet molecular oxygen generation under carcinomatous oxygen conditions.

Photophysics and photochemistry of octaglucosylated zinc phthalocyanine derivatives

2012 ◽  
Vol 16 (04) ◽  
pp. 413-422 ◽  
Author(s):  
Zafar Iqbal ◽  
Abimbola Ogunsipe ◽  
Tebello Nyokong ◽  
Alexey Lyubimtsev ◽  
Michael Hanack ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Molecular Oxygen ◽  
Ground State ◽  
Single Photon ◽  
Electronic Absorption Spectra ◽  
Zinc Phthalocyanine ◽  
Triplet States ◽  
Collisional Quenching ◽  
Quenching Rate ◽  
Yield Values

The ground state electronic absorption spectra, photophysics and photochemistry of amphiphilic octaglucosylated zinc phthalocyanines containing oxygen or sulfur bridges are presented. Triplet quantum yield values for the two dyes (in DMF and DMSO) vary between 0.71 and 0.84, while singlet quantum yield values lie between 0.63 and 0.75. Fluorescence lifetimes were determined experimentally by time correlated single photon counting and semi-empirically by fluorescence quenching techniques; and values from both methods were within the same range. Kinetic data were obtained for the quenching of the triplet state of the phthalocyanines by ground state molecular oxygen; the bimolecular collisional quenching rate constant range between 2.35 × 108 and 1.13 × 109 M-1.s-1. These values suggest that triplet states of the dyes are effectively quenched by ground molecular oxygen.

Photoluminescence and electron migration characteristics of aromatic poly(amide-imide) containing 1-naphthaldehyde and 4,4′-diamino diphenyl ether

e-Polymers ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Sepideh Khoee ◽  
Somayeh Zamani
Keyword(s):  
Diphenyl Ether ◽  
The Self ◽  
Quenching Rate ◽  
Fluorescent Band ◽  
Solvent Interaction ◽  
H Nmr ◽  
Association Reaction ◽  
Quenching Rate Constant ◽  
Ft Ir ◽  
Electron Migration

AbstractA new photoactive polymer poly(amide-imide), was fabricated by reacting two synthesized monomers, N,N'-(4,4'-oxy-bis(4,1-phenylene))-bis-(1,3- dioxo-1,3-dihydroisobenzofuran-5-carbox amide) and N-(4,6-diamino-1,3,5- triazine-2-yl)-1-naphthamide. Polycondensation reaction of the two monomers was performed under 10 min microwave irradiation in o-cresol as solvent for producing a photoactive poly(amide-imide) in a quantitative yield. The resulting polymer was characterized by FT-IR, 1H-NMR, TGA techniques and its solvatochromic and fluorescence properties were investigated in different solvents. The poly(amideimide) exhibit broad fluorescent band, and the fluorescence intensity is related to the intermolecular chain-chain or chain-solvent interaction. Also the self-quenching mechanism was studied according to the specific behavior of the polymer in different solvents and the self-quenching rate constant for the association reaction in the excited state (Kq) could be measured from the Stern-Volmer equation. This kind of fused system and diamines show various electron migration mechanisms and photoluminescent properties in the singlet excited states.

Absorption and Fluorescence Spectra of some 1,3,4-Oxadiazole Derivatives in n-Paraffins at 77 K

1978 ◽  
Vol 33 (6) ◽  
pp. 731-735 ◽  
Author(s):  
P. Bałuk ◽  
A. Kawski
Keyword(s):  
Infrared Spectra ◽  
Ground State ◽  
Fluorescence Spectra ◽  
Singlet State ◽  
Vibrational Structure ◽  
Excited Singlet State ◽  
Absorption And Fluorescence Spectra ◽  
Excited Singlet ◽  
Oxadiazole Derivatives

Abstract The quasilinear absorption and fluorescence spectra of 2- (1-naphthyl) -5-phenyl 1,3,4 oxadiazole, 2-(2-naphthyl)-5- phenyl 1,3,4 oxadiazole, 2-(1-naphthyl) -5-(4-biphenylyl) - 1,3,4 oxadiazole and 2-(2-naphthyl)-5-(4-biphenylyl)-1,3,4 oxadiazole have been studied in n-hexane, decane and nonane at 77 K. An analysis of the vibrational structure in the first electronic excited singlet state (S1) and in the ground state (S0) is given. Internal oscillations in the investigated molecules found from the quasilinear spectra are in agreement with those found in the infrared spectra.

Der Substituenteneinfluß auf die Fluoreszenz des 1.3-Diphenyl-2-pyrazolins / Substituent Effects on the Fluorescence of 1,3-Diphenyl-2-pyrazoline

1976 ◽  
Vol 31 (9) ◽  
pp. 1248-1255 ◽  
Author(s):  
H. Strähle ◽  
W. Seitz ◽  
H. Güsten
Keyword(s):  
Absorption Spectra ◽  
Ground State ◽  
Phenyl Ring ◽  
Fluorescence Spectra ◽  
Singlet State ◽  
Fluorescence Decay ◽  
Quantum Yields ◽  
Excited Singlet ◽  
Fluorescence Quantum Yields ◽  
Absolute Fluorescence

The electronic absorption spectra, absolute fluorescence spectra and fluorescence quantum yields as well as the fluorescence decay times of nine 1,3-diphenyl-2-pyrazolines substituted in the para-position of the 1-phenyl ring and of 19 substituted in the paraposition of the 3-phenyl ring were measured in degassed benzene at room temperature. The fluorescence quantum yields are about 0.90 with the exception of the NO2- and J-substituted 1,3-diphenyl-2-pyrazolines. The fluorescence decay time ranges from 2 to 4 nsec. The natural fluorescence lifetimes determined experimentally agree well with those calculated from the absorption spectra according to STRICKLER and BERG. A plot of the Hammett σp-values versus the energies of the absolute fluorescence maxima of the psubstituted 1- and 3-phenyl ring of the 2-pyrazoline system shows a statistically significant linear correlation with moderate precision. The linearity between ground state substituent constants and fluorescence energies reveals that the relative importance of the inductive and the resonance effects of the substituents remains constant during the transition from the ground state to the relaxed excited singlet state. In the excited singlet state of 1,3-diphenyl-2-pyrazoline the p-substituents provide more room for a larger charge displacement in the intramolecular charge-transfer. The structural bands in the fluorescence spectra resulting from strong electron accepting substituents in the para-position of the 1-phenyl ring are considered as the result of the ring breathing vibration due to a local excitation of the 1-phenyl ring.

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