Acid/base-triggered switching of circularly polarized luminescence and electronic circular dichroism in organic and organometallic helicenes.
Chemistry
; 21(4): 1673-81, 2015 Jan 19.
Article
em En
| MEDLINE
| ID: mdl-25418503
ABSTRACT
Electronic circular dichroism and circularly polarized luminescence acid/base switching activity has been demonstrated in helicene-bipyridine proligand 1 a and in its "rollover" cycloplatinated derivative 2 a. Whereas proligand 1 a displays a strong bathochromic shift (>160â
nm) of the nonpolarized and circularly polarized luminescence upon protonation, complex 2 a displays slightly stronger emission. This strikingly different behavior between singlet emission in the organic helicene and triplet emission in the organometallic derivative has been rationalized by using quantum-chemical calculations. The very large bathochromic shift of the emission observed upon protonation of azahelicene-bipyridine 1 a has been attributed to the decrease in aromaticity (promoting a charge-transfer-type transition rather than a π-π* transition) as well as an increase in the HOMO-LUMO character of the transition and stabilization of the LUMO level upon protonation.
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Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Compostos Organoplatínicos
/
Compostos Policíclicos
Idioma:
En
Revista:
Chemistry
Assunto da revista:
QUIMICA
Ano de publicação:
2015
Tipo de documento:
Article