Liuqing Sun
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Research Subjects
Research Interests
Liuqing Sun has a total of 13 co-authors. Here are the top co-authors by number of shared publications:
- Adelia Justina Aguiar Aquino
Department of Mechanical Engineering, Texas Tech University, Lubbock, TX 79409, USA
1 shared publication - Adilson Alves de Freitas
Centro de Química Estrutural, Institute of Molecular Sciences, Instituto Superior Técnico, Universidade de Lisboa , Av. Rovisco Pais, 1049-001 Lisboa
1 shared publication - Cassio P. Silva
Instituto de Química, Universidade de São Paulo, Avenida Lineu Prestes 748, São Paulo 05508-900, Brazil
1 shared publication - Frank Herbert Quina
Universidade de São Paulo
1 shared publication - Gustavo Thalmer de Medeiros Silva
Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
1 shared publication - Jennifer Rozendo
Instituto de Química, Universidade de São Paulo, Avenida Lineu Prestes 748, São Paulo 05508-900, Brazil
1 shared publication
Latest Publications
- Open Access
Fluorescence and Phosphorescence of Flavylium Cation Analogues of Anthocyanins
Fluorescence spectra and lifetimes were determined for 16 synthetic flavylium cation analogues of anthocyanin plant pigments in dry acetonitrile acidified with trifluoroacetic acid (TFA). Phosphorescence was also observed from the lowest excited triplet state for all of the flavylium cations at 77 K in a rigid TFA-acidified isopropanol glass. The fluorescence quantum yields and lifetimes depend in a systematic manner on the nature and position of the substituents on the flavylium chromophore and three specific substitution patterns associated with significant decreases in the fluorescence quantum yield were identified. A 4′-bromo or 4′-iodo substituent in the B-ring of the flavylium cation produced a small but normal heavy-atom effect, reducing the fluorescence quantum yield and the phosphorescence lifetime relative to analogues without the halogen atom. In contrast, three flavylium cations with a 3′-bromo substituent exhibited an “inverse” heavy atom effect, i.e., an increase in the fluorescence quantum yield rather than a decrease, which was rationalized on the basis of the nodal properties of the natural transition orbitals (NTOs) involved in the S0→S1 radiative transition.
Open AccessFluorescence and Phosphorescence of Flavylium Cation Analogues of Anthocyanins
Fluorescence spectra and lifetimes were determined for 16 synthetic flavylium cation analogues of anthocyanin plant pigments in dry acetonitrile acidified with trifluoroacetic acid (TFA). Phosphorescence was also observed from the lowest excited triplet state for all of the flavylium cations at 77 K in a rigid TFA-acidified isopropanol glass. The fluorescence quantum yields and lifetimes depend in a systematic manner on the nature and position of the substituents on the flavylium chromophore and three specific substitution patterns associated with significant decreases in the fluorescence quantum yield were identified. A 4′-bromo or 4′-iodo substituent in the B-ring of the flavylium cation produced a small but normal heavy-atom effect, reducing the fluorescence quantum yield and the phosphorescence lifetime relative to analogues without the halogen atom. In contrast, three flavylium cations with a 3′-bromo substituent exhibited an “inverse” heavy atom effect, i.e., an increase in the fluorescence quantum yield rather than a decrease, which was rationalized on the basis of the nodal properties of the natural transition orbitals (NTOs) involved in the S0→S1 radiative transition.