Banca de DEFESA: DANILO GLEIBSON BERNARDO DA SILVA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : DANILO GLEIBSON BERNARDO DA SILVA
DATE: 10/01/2024
TIME: 09:00
LOCAL: Programa de Pós-Graduação em Ciência de Materiais
TITLE:

SYNTHESIS OF LIQUID CRYSTALS BASED ON BISPERYLENIMIDES AND THEIR APPLICATION IN OBTAINING ANISOTROPIC NMR PARAMETERS

KEY WORDS:

Chromonic phases. Chiral liquid crystals. Bisperylenimides. Structural elucidation. NMR. RDC. RCSA

PAGES: 187
BIG AREA: Outra
AREA: Multidisciplinar
SUMMARY:

The present work aims to prepare new lyotropic liquid crystals, and to study their application to NMR spectroscopy as chiral alignment media for aqueous solutions. Two chiral and one achiral mesogenic bisimides derived from the conjugation of dianhydrideperylenetetracarboxylic acid (BPI) with the amino acids: L-valine (BPI-LVal), L-leucine (BPI-LLeu) and Glycine (BPI-Gly) were synthesized with yields of 78% , 75% and 82%, respectively. The compounds were characterized by 1 H and 13C NMR. The study of the concentration and temperature influence on the formation of the nematic phase was studied by 2H NMR spectroscopy. The best conditions for using these mesogens as alignment media corresponded to 0.5M solution at 23oC for BPI-LVal, 0.3M at 27oC for BPI-LLeu, and 0.2M at 25oC for BPI-Gli. To evaluate the efficiency of the nematic phases as alignment media for measuring residual dipolar couplings (RDCs) and residual chemical shift anisotropies (RCSAs) two test molecules were used: sucrose and 5-norbornen-2-ol. The mesogens BPI-LVal and BPI-Gli showed to be the most efficient alignment media for NMR applications. The alignment medium formed by BPI-LVal had the advantage of enabling the acquisition of isotropic and anisotropic parameters at the same temperature. The BPI- LLeu compound formed the nematic phase, and indicated to be efficient in determining the conformation of the sucrose molecule. The BPI-Gli compound formed the nematic phase with a lower concentration of mesogen, facilitating the measurement of RDCs and RCSAs values, providing narrower signals.

COMMITTEE MEMBERS:
Externa à Instituição - MARIA MAGDALENA CID FERNÁNDEZ
Presidente - 2215007 - FERNANDO HALLWASS
Interna - 2330165 - MARIA GORETI CARVALHO PEREIRA
Externo ao Programa - 3340247 - RODOLFO HIDEKI VICENTE NISHIMURA - nullExterno à Instituição - RUBENS RODRIGUES TELES - IFPB