In silico modeling of functionalized graphene oxide-metal cluster conjugates as Raman probe: Raman activity of pyridine

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• 作者：Dewei Chen ; Christopher Copeland ; D. Majumdar ; Szczepan Roszak…
• 关键词：Functionalized graphene oxide ; Graphene oxide ; metal conjugates ; Raman probe ; Raman Intensity ; Polarizability ; Vibrational Spectra ; Raman Spectra
• 刊名：Structural Chemistry
• 出版年：2017
• 出版时间：April 2017
• 年：2017
• 卷：28
• 期：2
• 页码：379-389
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Computer Applications in Chemistry; Physical Chemistry; Theoretical and Computational Chemistry;
• 出版者：Springer US
• ISSN：1572-9001
• 卷排序：28

文摘

Functionalized graphene – metal nano-conjugates are used as Raman probes, in recent years, for trace level identification of materials having specific Raman active modes. In the present paper, model Raman probes were modeled through conjugation of Au₄ and Ag₄ clusters with functionalized graphene systems. In silico models of functionalized (5,5)-graphene sheets were designed at the density functional theory (DFT) level through attachments of epoxy, -OH and –NH(CH₃)₂SH/-CONH(CH₃)₂SH groups. Model Raman probes were designed through attachment of Au₄ and Ag₄ clusters to the functional sites. Full geometry optimizations followed by vibrational analysis were carried out to ensure that the designed Raman probes have acceptable geometric characteristics to attach Raman-active molecules to the metal site. Pyridine was used as a test system to investigate the functionality of such model Raman probes through attachment with the metal clusters. It was observed that the chemical effects due to such attachments increase the Raman intensities (RI) of specific Raman modes of pyridine (in-plane symmetric bending (1040 cm-1) and asymmetric stretch-bend (1634 cm-1)), which are too weak in the isolated molecule. Furthermore, the suggested in silico system could provide an important model for basic understanding of RI-enhancements of molecules through increase of the size of the metal clusters, as the observed enhancement was found to be dependent on the polarizability of the metal clusters attached to the molecule of interest.