scholarly journals Spectral Properties of Dyes with Interfragmental Charge Transfer: Solvatochromism and Solvatofluorochromism of 2-(3-Coumaroyl)-benzopyrylium Perchlorates

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Edward V. Sanin ◽  
Alexander I. Novikov ◽  
Alexander D. Roshal
Keyword(s):  
Charge Transfer ◽  
Spectral Properties ◽  
Spectral Characteristics ◽  
Quantum Yields ◽  
Absorption Bands ◽  
Long Wavelength ◽  
Solvent Parameters ◽  
Wavelength Absorption ◽  
Solvent Molecules ◽  
The Stability

The paper deals with the spectral properties of dyes with interfragmental charge transfer, in particular, derivatives of 2-(3-coumaroyl)benzopyrylium (CBP) perchlorates. The positions of long-wavelength absorption and emission bands, quantum yields, and lifetimes of fluorescence were measured, mostly in aprotic solvents. Regression analysis of the relationship between the spectral characteristics of CBP and the main solvent parameters (polarity, polarisability, nucleophilicity, and electrophilicity) was carried out. It was found that the characteristics of CBP depend mainly on two solvent parameters—polarity and/or nucleophilicity. An increase in these parameters results in a hypsochromic shift of absorption bands and a decrease of lifetimes and fluorescence intensity. The positions of the emission bands can demonstrate either hypsochromism or bathochromism, depending on the nature of the substituents. The solvatofluorochromic effects are not as strong as the solvatochromic ones. We believe that the spectral behaviour of CBP can be explained by cation depolarisation and by a decrease in the stability of nucleophilic complexes with solvent molecules that is associated with interfragmental charge transfer following excitation, relaxation, and radiative deactivation of the excited state.

Photocytotoxicity of Anthracyclines upon Laser Excitation in Their Long-Wavelength Absorption Bands

1991 ◽  
Vol 127 (1) ◽  
pp. 24 ◽  
Author(s):  
Alessandra Andreoni ◽  
Alberto Colasanti ◽  
Vincenzo Malatesta ◽  
Giuseppe Roberti
Keyword(s):  
Laser Excitation ◽  
Absorption Bands ◽  
Long Wavelength ◽  
Wavelength Absorption

Synthesis and spectroscopic properties of benzo- and naphthofuryl-3-hydroxychromones

2001 ◽  
Vol 79 (4) ◽  
pp. 358-363 ◽  
Author(s):  
Andrey S Klymchenko ◽  
Turan Ozturk ◽  
Vasyl G Pivovarenko ◽  
Alexander P Demchenko
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Spectroscopic Properties ◽  
Molecular Probe ◽  
Absorption Bands ◽  
Methyl Group ◽  
Long Wavelength ◽  
Excited State Proton Transfer ◽  
Wavelength Absorption ◽  
Long Wavelength Absorption Band

With the focus of designing new fluorescent probes, four new 3-hydroxy-chromone derivatives bearing benzofuran and naphthofuran groups were synthesized. They show bathochromic absorption shifts relative to 3-hydroxyflavone with the ability of retention to display the excited-state proton transfer. Disruption of the planarity by the methyl group in the furan ring leads to a decrease of both the extinction coefficient and the contribution of long wavelength absorption band, while molecules without a methyl group showed two distinct absorption bands. Shifts to longer wavelengths are also observed in fluorescent spectra, and the absence of the methyl group results in a dramatic increase of fluorescence quantum yield and lifetime. Of the extended 3-hydroxychromone derivatives, 3-hydroxy-2-naphtho[2,1-b]furan-2-yl-chromone has shown comparable, and in some cases better, absorption and fluorescence properties than the 3-hydroxychromones synthesized so far, which make it a highly promising candidate as molecular probe for analytical chemistry, biophysics, and cellular biology.Key words: benzo- and naphthofuryl-3-hydroxyflavone, synthesis, electronic spectra, fluorescence, excited state proton transfer.

Conjugated Compounds. II. Simple Potential Energy Functions, Absorption Spectra, and Ionization in Linear Polyenes

1950 ◽  
Vol 3 (1) ◽  
pp. 109 ◽  
Author(s):  
NS Bayliss
Keyword(s):  
Potential Energy ◽  
Absorption Bands ◽  
Energy Functions ◽  
Potential Energy Functions ◽  
Long Wavelength ◽  
Linear Polyenes ◽  
Wavelength Absorption ◽  
Two Parameters ◽  
Simple Potential ◽  
Conjugated Compounds

The π-electrons of a linear conjugated system are considered in terms of two simple models for the potential energy, (A) a rectangular well and (B) a " cosine-squared " well. In each case it is possible to account quantitatively for the positions of long wavelength absorption bands, their intensities, and the ionization energies in ethylene, butadiene, hexatriene, and octatetraene with the use of two parameters, the breadth and depth of the well. By comparing the models with actual periodic potential energies calculated along the long axes of polyene molecules, it is shown that an effective nuclear charge of carbon of Z?≈1 is appropriate for the models under consideration. The assumptions involved in the application of simple one-dimensional potential energy functions to linear conjugated systems are considered in detail.

Photolysis of Naphthol Green B in Aqueous Solution. Photoreduction of Fe(III) Induced by Ligand-to-Metal Charge Transfer Excitation

2003 ◽  
Vol 58 (9) ◽  
pp. 922-924 ◽  
Author(s):  
Horst Kunkely ◽  
Arnd Vogler
Keyword(s):  
Aqueous Solution ◽  
Charge Transfer ◽  
Quantum Yield ◽  
Metal Charge ◽  
Long Wavelength ◽  
Mlct Transition ◽  
Wavelength Absorption ◽  
Charge Transfer Excitation ◽  
Naphthol Green B ◽  
Metal Charge Transfer

The intense long-wavelength absorption of Naphthol Green B at λmax = 712 nm is assigned to a ligand-to-metal charge transfer (MLCT) transition. LMCT excitation of the complex in aqueous solution leads to the reduction of Fe(III) to Fe(II) with a quantum yield of ϕ = 1.14×10−3 at λirr = 577 nm.

Photodisproportionation of (1,5-Cyclooctadiene) copper(I) Hexafluoroacetylacetonate Induced by Metal-to-Ligand Charge Transfer Excitation

2003 ◽  
Vol 58 (7) ◽  
pp. 704-707 ◽  
Author(s):  
Horst Kunkely ◽  
Arnd Vogler
Keyword(s):  
Excited State ◽  
Charge Transfer ◽  
Quantum Yields ◽  
Long Wavelength ◽  
Ligand Charge Transfer ◽  
Elemental Copper ◽  
Charge Transfer Excitation ◽  
Reactive Excited State

The complex CuI(COD)(hfac) with COD = 1,5- cyclooctadiene and hfac = hexafluoroacetyl-acetonate shows two long-wavelength absorptions at λmax = 308 and 241 nm which are assigned to hfac intraligand (IL) and CuI →COD metal-to-ligand charge transfer (MLCT) transitions, respectively. The photolysis of CuI(COD)(hfac) in hexane leads to the release of the olefin and the subsequent disproportionation of CuI(hfac) to elemental copper and CuII(hfac)2 with the quantum yields Φ = 10−3 at λirr =313 nm and Φ = 3×10−3 at λirr = 254 nm. It is suggested that the reactive excited state is of the MLCT type.

scholarly journals Synthesis and Photophysical Properties of a Series of Dimeric Indium Quinolinates

Molecules ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 34
Author(s):  
Sang Woo Kwak ◽  
Ju Hyun Hong ◽  
Sang Hoon Lee ◽  
Min Kim ◽  
Yongseog Chung ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Nmr Spectroscopy ◽  
1H Nmr Spectroscopy ◽  
Photophysical Properties ◽  
Emission Spectra ◽  
Solvent Polarity ◽  
Low Energy ◽  
Quantum Yields ◽  
Absorption Bands ◽  
Indium Complexes

A novel class of quinolinol-based dimeric indium complexes (1–6) was synthesized and characterized using 1H and 13C(1H) NMR spectroscopy and elemental analysis. Compounds 1–6 exhibited typical low-energy absorption bands assignable to quinolinol-centered π–π* charge transfer (CT) transition. The emission spectra of 1–6 exhibited slight bathochromic shifts with increasing solvent polarity (p-xylene < tetrahydrofuran (THF) < dichloromethane (DCM)). The emission bands also showed a gradual redshift, with an increase in the electron-donating effect of substituents at the C5 position of the quinoline groups. The absolute emission quantum yields (ΦPL) of compounds 1 (11.2% in THF and 17.2% in film) and 4 (17.8% in THF and 36.2% in film) with methyl substituents at the C5 position of the quinoline moieties were higher than those of the indium complexes with other substituents.

Photoreactivity of Titanocene Pentasulfide

1998 ◽  
Vol 53 (2) ◽  
pp. 224-226 ◽  
Author(s):  
Horst Kunkely ◽  
Arnd Vogler
Keyword(s):  
Charge Transfer ◽  
Electronic Spectrum ◽  
Elemental Sulfur ◽  
Reductive Elimination ◽  
Metal Charge ◽  
Long Wavelength ◽  
Wavelength Absorption ◽  
Metal Charge Transfer

Abstract The electronic spectrum of Cp2TiS5 shows a long-wavelength absorption at λ max = 492 nm which is assigned to the lowest-energy S52- → TiIV ligand-to-metal charge transfer (LMCT) transition. The photolysis of the complex in CH2CI2 leads to the formation of Cp2TiCl2 and elemental sulfur. It is suggested that LMCT excitation initiates a reductive elimination with the extrusion of S5 while the reduced titanocene is reoxidized by the solvent.

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