Electronic spectral data salts

Electronic spectral data for selected pyridoazepine bases and their salts can be found in Tables 11 and 12, respectively. Data have additionally been reported with reference to cyclic diimide 32 (64CB1548), to homoberbines 157a and b and 158 (69HCA1228) as well as 160 and 161 (69JC874), and to hydroperchlorates, for instance, of homoberbine 209b (87LA639). 

In a similar way, the formation of halide complexes with other jt-acceptors in Fig. 3 are revealed by the appearance of new absorption bands in the electronic spectra to reflect the yellow to red colorations of the mixtures. The spectral data thus indicate that halide salts form well-defined electron donor/acceptor complexes with organic jt-acceptors, as typified by Eq. 2 ... 

The same argument can be made for each alkali atom because there is only one outer electron, one can model an alkah atom as a hydrogen-like atom with one electron and a nucleus made up of the true nucleus and the inner electrons. As above, this argument hinges on the fact that the inner electrons tend to be in the lowest possible states, while the Pauli exclusion principle forbids any two electrons from occupying the same state. And indeed, spectral data for alkali atoms resembles spectral data for hydrogen. Moreover, the chemical properties of the alkali atom is similar. For example, each combines easily with chlorine to form a salt such as potassium chloride, lithium chloride... 

Ultraviolet and NMR spectroscopic determinations are available of the pK and cationic stability of both isomeric (7 and 8) salts. " The existence of a sulfonium sulfur in a conjugated system has been of molecular orbital interest, and some of these data have been correlated with electronic spectra. " The NMR spectral data for both 7 and 8 have been rejiorted, and in the former case the protons a and y to the sulfonium center are the most deshielded. Further, the NMR indicates considerable conjugation through the sulfur in the 1-benzo-thiopyrylium system. ... 

All physical properties of pyrylium salts (unsubstituted or substituted with alkyl and/or aryl groups) prove the aromaticity of these cations vibrational spectra [66], mass-spectral fragmentations [67], magnetic properties [68-70], and electronic absorption spectra [71]. It should be mentioned that there is a close similarity between the electronic absorption bands of pyrylium salts and those of benzene, easily recognized by the marked bathochromic effect of substituents in y-position of pyrylium salts on one of these bands. Two-photon absorption spectra of 2,4,6-triarylpyrylium cations [72] may be used in optical data storage, lasing, and photodynamic therapy. 

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