Characterization of phenomena occurring at the interface of chiral conducting surfaces

• Published in: New journal of chemistry 2014, Vol.38 (8), p.3379-3385
• Main Authors: Chahma, M'hamed, McTiernan, Christopher D., Abbas, Sara A.
• Format: Article
• Language: English
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/C4NJ00489B

The ability of the chiral electrode based on l -leucine functionalized terthiophene (poly( 1 )-Pt) to recognize and detect biomolecules has been studied as a function of hydrogen bonding between the chiral surface and a free l -leucine methyl ester. We characterized electrochemically the formation of hydrogen bonds by cyclic voltammetry (CV). The results show that the capacitive current of the chiral electrode poly( 1 )-Pt decreased by 30% due to hydrogen bonding between the chiral electrode and the free added l -leucine methyl ester. The origin of the hydrogen bonds on poly( 1 )-Pt has been confirmed by attenuated total reflection Fourier transform infrared (ATR-FTIR) using trifluoroacetic acid (CF 3 COOH) as free H-bonding species. The ATR-FTIR spectrum exhibits functionalities of free CF 3 COOH that form hydrogen bonds with the chiral conducting surface of poly( 1 )-Pt. Due to the insolubility of poly( 1 ), NMR studies were performed on the parent monomers. The chemical shift of the amide proton in the 1 H-NMR of the l -leucine functionalized terthiophene ( 1 ) shifted after addition of l -leucine methyl ester. Similar trends were observed for the carboxylic carbonyl of l -leucine methyl ester-terthiophene 2 in the 13 C-NMR. In addition to the change in the 13 C chemical shift, there is a considerable change in the spin–lattice relaxation time of the carbonyl carbon in 2 due to the formation of hydrogen bonds between the –COOH of 2 and the imidazole.