Fluorescence spectra solvent effects

Diels-Alder reactions, 4, 842 flash vapour phase pyrolysis, 4, 846 reactions with 6-dimethylaminofuKenov, 4, 844 reactions with JV,n-diphenylnitrone, 4, 841 reactions with mesitonitrile oxide, 4, 841 structure, 4, 715, 725 synthesis, 4, 725, 767-769, 930 theoretical methods, 4, 3 tricarbonyl iron complexes, 4, 847 dipole moments, 4, 716 n-directing effect, 4, 44 2,5-disubstituted synthesis, 4, 116-117 from l,3-dithiolylium-4-olates, 6, 826 electrocyclization, 4, 748-750 electron bombardment, 4, 739 electronic deformation, 4, 722-723 electronic structure, 4, 715 electrophilic substitution, 4, 43, 44, 717-719, 751 directing effects, 4, 752-753 fluorescence spectra, 4, 735-736 fluorinated derivatives, 4, 679 H NMR, 4, 731 Friedel-Crafts acylation, 4, 777 with fused six-membered heterocyclic rings, 4, 973-1036 fused small rings structure, 4, 720-721 gas phase UV spectrum, 4, 734 H NMR, 4, 7, 728-731, 939 solvent effects, 4, 730 substituent constants, 4, 731 halo... 

Gorsuch and Hercules 109> stated that certain discrepancies between the fluorescence spectrum of 3-amino-phthalate dianion and the chemiluminescence spectrum of luminol are partly due to reabsorption of the shorter-wavelength chemiluminescence light by the luminol monoanion. These authors confirmed the results of E. H. White and M. M. Bursey 114> concerning the very essential solvent effect on luminol chemiluminescence the relative intensity of the latter in anhydrous DMSO/t-BuOK/ oxygen was found to be about 30,000 times that in DMSO/28 mole % water/potassium hydroxide/oxygen. 

Such a solvent relaxation explains the increase in the red-shift of the fluorescence spectrum as the polarity of the solvent increases. The effect of polarity on fluorescence emission will be further discussed in Chapter 7, together with polarity probes. Moreover, when a cation receptor is linked to an intramolecular charge transfer fluorophore so that the bound cation can interact with either the donor group or the acceptor group, the ICT is perturbed the consequent changes in photophysical properties of the fluorophore can be used for sensing cations (see Section 10.3.3). 

It should be recalled that, in polar rigid media, excitation on the red-edge of the absorption spectrum causes a red-shift of the fluorescence spectrum with respect to that observed on excitation in the bulk of the absorption spectrum (see the explanation of the red-edge effect in Section 3.5.1). Such a red-shift is still observable if the solvent relaxation competes with the fluorescence decay, but it disappears in fluid solutions because of dynamic equilibrium among the various solvation sites. 

Experimentally, these effects are tested by fluorescence and absorption measurements. These directly probe solvent polarization dynamics on molecular time-scales [100, 101]. For instance, the time resolved fluorescence spectrum of a chromophore, whose excited state dipole moment is subject to interactions with the surrounding solvent molecules, will exhibit fluorescence spectra that are strongly solvent dependent. The solvent molecules attempt to compensate the changes of charge density in the chromophore and, in sum, the fluorescence... 

Solvent effects on the fluorescence spectrum and the effect of protonation on electron density and chemical shift in NMR spectrum of pyridazine were investigated. 

Another example of intramolecular CT complex formation is provided by trans-4-dimethvlamino-4 -(1-oxobutvl)stilbene Solvent effects on the spectrum give a value of 22D for the excited state dipole moment. The effect of electric field on the fluorescence of 4-(9-anthry1)-N.N.-2.3,5,G-hexamethy1-aniline shows this compound forms an excited state whose dipole moment does not change with solvent . Chiral discrimination in exciplex formation between 1-dipyrenylamine and chiral amines is very weak . In the probe molecule PRODAN (6-propionyl)-2-(dimethylamino)—naphthalene the initially formed excited state converts to a lower CT state as directly evidenced by time-resolved spectra in n-butanol. Rate constants for intramolecular electron transfer have been measured in both singlet and triplet states of covalently porphyrin-amide-quinone molecules . Intramolecular excimer formation occurs during the lifetime of the excited state of bis-(naphthalene)hydrazides which are used as photochemical deactivators of metals in polyethylene . ... 

Figures 22 and 23 offer a closer look at the absorption and fluorescence spectra of several 1-naphthol derivatives in methanol. In the case of sulfonate-substituted 1-naphthols, the substituent effect on the absorption spectra is relatively small, while a considerable effect is observed in the corresponding fluorescence spectra of the photoacids. This effect resembles the solvent effect on the fluorescence spectrum of the parent 1-naphthol molecule. Using the analogy to the effect of solvent polarity on the spectra, the ring position of the sulfonate group seems to appear more polar , moving from the 2- to the...

P>MA Particles. PIB-stabilized PbWA particles were prepared containing naphthalene [N] groups covalently attached to the fTWA chains. This was effected quite simply by adding l naphthylmethyl methacrylate to the NWA polymerization step of the particle synthesis. From reactivity ratios, one knows that the N groups are randomly distributed along the P>MA chains. The particles were purified by repeated centrifugation, replacement of the supernatant serum with fresh solvent (isooctane) and redispersion. A fluorescence spectrum of the dispersion was typical of that of a 1-alkyl-naphthalene. Chemical analysis indicated a particle composition IB/NWA/N of 13/100/10. 

UV spectra of pyridazines and pyridazinones were recorded, and solvent effects on spectra were examined. 644-652 The absorption spectrum of the pyridazine radical was reported.653 Resonance fluorescence has been observed from pyridazine vapor.654 Electron transmission spectroscopy has... 

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