| Abstrakt: |
The π-π electronic excitation of hydroxycarbonium ions (HCI), obtained from heterocyclic analogs of chalcone and its vinylogs $$[\Gamma - \mathop {C(OH) - CH = CH)_n - Ar;}\limits^ + \Gamma = $$ dibenzofuran, dibenzothiophene, carbazole; n = 1,2] by reaction with 96% HSO,-has been analyzed with the object of establishing relations between the structure of the HCI and their spectroscopic characteristics. By comparing experimental data, the results of calculation, and indices giving a quantitative description of the electronic excitation, it was shown that in the long-wave region (330-550 nm) of the electronic spectra of the HCI there are two types of excitation, one involving predominantly the whole of the molecule (intense S-S and S-S transition of the p type) and the other involving predominantly molecular fragments (weak S-S and S-S transitions of the α type). The transition S-S is localized mainly on the fragment Γ- $$\Gamma - \mathop {C(OH) - (CH = CH)_n - }\limits^ + $$ -[charge transfer Γ→ $$\mathop {C(OH) - (CH = CH)_n - ]}\limits^ + $$ and the transition S-S on the fragment $$ - \mathop {C(OH) - (CH = CH)_n }\limits^ + $$ -Ar [charge transfer Ar → -(CH=CH)- $$\mathop { - C}\limits^ + (OH) - ]$$ (OH)-]. [ABSTRACT FROM AUTHOR] |
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