Zwitterion L-cysteine adsorbed on the Au₂₀ cluster: enhancement of infrared active normal modes.
The study reported herein addressed the structure, adsorption energy and normal modes of zwitterion L-cysteine (Z-cys) adsorbed on the Au₂₀ cluster by using density functional theory (DFT). It was found that four Z-cys are bound to the Au₂₀ apexes preferentially through S atoms. Regarding normal modes, after adsorption of four Z-cys molecules, a more intense infrared (IR) peak is maintained around 1,631.4 cm(-1) corresponding with a C=O stretching mode, but its intensity is enhanced approximately six times. The enhancement in the intensity of modes between 0 to 300 cm(-1) is around 4.5 to 5.0 times for normal modes that involve O-C=O and C-S bending modes. Other two normal modes in the range from 300 to 3,500 cm(-1) show enhancements of 6.0 and 7.4 times. In general, four peaks show major intensities and they are related with normal modes of carboxyl and NH₃ groups of Z-cys.
Department of Physics and Astronomy, University of Texas at San Antonio, One UTSA Circle, San Antonio, TX 78249, USA. tlahuicef@gmail.com
Alfredo
A
Tlahuice-Flores
D000327:Adsorption; D003545:Cysteine / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D008956:Models, Chemical; D011789:Quantum Theory; D013055:Spectrophotometry, Infrared
D006046:Gold; D003545:Cysteine