Surface enhanced Raman spectroscopic (SERS) behavior of substituted propenoic acids used in heterogeneous catalytic asymmetric hydrogenation

Tamás Firkala, Emília Tálas, S. Kristyán, György Szöll'si, Eszter Drotár, J. Mink, J. Mihály

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Abstract

The strength and geometry of adsorption of substituted propenoic acids on silver surface were studied by means of surface enhanced Raman spectroscopy (SERS) using silver sol. Based on their SERS behavior, two classes of phenylpropenoic acids studied were distinguished. The first class of propenoic acids (atropic acid, (E)-2,3-diphenylpropenoic acid, (E)-2-(2-methoxyphenyl)-3-phenylpropenoic acid, (E)-2,3-di-(4-methoxyphenyl)phenylpropenoic acid and (E)-2-(2-methoxyphenyl)-3-(4-fluorophenyl)propenoic acid) has shown strong charge transfer (CT) effect. We suggest bidentate carboxyl bonded species based on the SERS enhanced bands of νCOO- around 1394cm-1 and νC-C of the -C-COO- moiety at 951cm-1. In these series the plane of the α-phenyl group (γCH out-of-plane vibrations at 850-700cm-1) is almost parallel to the silver surface, while the β-phenyl group is in tilted position depending on the type and the position of substituent(s) showing strong SERS enhanced bands of νCC+βCH (in-plane mode) at 1075cm-1, νCC (ring breathing mode, in-plane) at 1000cm-1 and γCCC (out-of-plane mode) around 401cm-1. The other class of propenoic acids (cinnamic acid, (E)-2-phenyl-3-(4-methoxyphenyl)propenoic acid) has shown weak electromagnetic (EM) enhancement (CC bands is enhanced in cinnamic acid). In this case no significant carboxyl enhancement was observed, so we suggest that adsorbed species lie parallel to the surface. The two types of adsorption can be related to the dissociation ability of the carboxylic group. In the first case the carboxylic H dissociates, while in the second case it does not, as indicated also by the characteristic νCO band at 1686cm-1 in the FT-Raman spectra of methanolic solutions.

Original languageEnglish
JournalJournal of Raman Spectroscopy
DOIs
Publication statusAccepted/In press - 2015

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Hydrogenation
Acids
Silver
Adsorption
Polymethyl Methacrylate
Carbon Monoxide
Raman spectroscopy
Charge transfer
Raman scattering
Sols
Geometry

Keywords

  • 4-hydroxy benzoic acid
  • Adsorption geometry
  • Enantioselective hydrogenation
  • Phenylpropenoic acids
  • SERS

ASJC Scopus subject areas

  • Spectroscopy
  • Materials Science(all)

Cite this

@article{f9ec8ea1803f4ea7b69b442ff81ee408,
title = "Surface enhanced Raman spectroscopic (SERS) behavior of substituted propenoic acids used in heterogeneous catalytic asymmetric hydrogenation",
abstract = "The strength and geometry of adsorption of substituted propenoic acids on silver surface were studied by means of surface enhanced Raman spectroscopy (SERS) using silver sol. Based on their SERS behavior, two classes of phenylpropenoic acids studied were distinguished. The first class of propenoic acids (atropic acid, (E)-2,3-diphenylpropenoic acid, (E)-2-(2-methoxyphenyl)-3-phenylpropenoic acid, (E)-2,3-di-(4-methoxyphenyl)phenylpropenoic acid and (E)-2-(2-methoxyphenyl)-3-(4-fluorophenyl)propenoic acid) has shown strong charge transfer (CT) effect. We suggest bidentate carboxyl bonded species based on the SERS enhanced bands of νCOO- around 1394cm-1 and νC-C of the -C-COO- moiety at 951cm-1. In these series the plane of the α-phenyl group (γCH out-of-plane vibrations at 850-700cm-1) is almost parallel to the silver surface, while the β-phenyl group is in tilted position depending on the type and the position of substituent(s) showing strong SERS enhanced bands of νCC+βCH (in-plane mode) at 1075cm-1, νCC (ring breathing mode, in-plane) at 1000cm-1 and γCCC (out-of-plane mode) around 401cm-1. The other class of propenoic acids (cinnamic acid, (E)-2-phenyl-3-(4-methoxyphenyl)propenoic acid) has shown weak electromagnetic (EM) enhancement (CC bands is enhanced in cinnamic acid). In this case no significant carboxyl enhancement was observed, so we suggest that adsorbed species lie parallel to the surface. The two types of adsorption can be related to the dissociation ability of the carboxylic group. In the first case the carboxylic H dissociates, while in the second case it does not, as indicated also by the characteristic νCO band at 1686cm-1 in the FT-Raman spectra of methanolic solutions.",
keywords = "4-hydroxy benzoic acid, Adsorption geometry, Enantioselective hydrogenation, Phenylpropenoic acids, SERS",
author = "Tam{\'a}s Firkala and Em{\'i}lia T{\'a}las and S. Kristy{\'a}n and Gy{\"o}rgy Sz{\"o}ll'si and Eszter Drot{\'a}r and J. Mink and J. Mih{\'a}ly",
year = "2015",
doi = "10.1002/jrs.4741",
language = "English",
journal = "Journal of Raman Spectroscopy",
issn = "0377-0486",
publisher = "John Wiley and Sons Ltd",

}

TY - JOUR

T1 - Surface enhanced Raman spectroscopic (SERS) behavior of substituted propenoic acids used in heterogeneous catalytic asymmetric hydrogenation

AU - Firkala, Tamás

AU - Tálas, Emília

AU - Kristyán, S.

AU - Szöll'si, György

AU - Drotár, Eszter

AU - Mink, J.

AU - Mihály, J.

PY - 2015

Y1 - 2015

N2 - The strength and geometry of adsorption of substituted propenoic acids on silver surface were studied by means of surface enhanced Raman spectroscopy (SERS) using silver sol. Based on their SERS behavior, two classes of phenylpropenoic acids studied were distinguished. The first class of propenoic acids (atropic acid, (E)-2,3-diphenylpropenoic acid, (E)-2-(2-methoxyphenyl)-3-phenylpropenoic acid, (E)-2,3-di-(4-methoxyphenyl)phenylpropenoic acid and (E)-2-(2-methoxyphenyl)-3-(4-fluorophenyl)propenoic acid) has shown strong charge transfer (CT) effect. We suggest bidentate carboxyl bonded species based on the SERS enhanced bands of νCOO- around 1394cm-1 and νC-C of the -C-COO- moiety at 951cm-1. In these series the plane of the α-phenyl group (γCH out-of-plane vibrations at 850-700cm-1) is almost parallel to the silver surface, while the β-phenyl group is in tilted position depending on the type and the position of substituent(s) showing strong SERS enhanced bands of νCC+βCH (in-plane mode) at 1075cm-1, νCC (ring breathing mode, in-plane) at 1000cm-1 and γCCC (out-of-plane mode) around 401cm-1. The other class of propenoic acids (cinnamic acid, (E)-2-phenyl-3-(4-methoxyphenyl)propenoic acid) has shown weak electromagnetic (EM) enhancement (CC bands is enhanced in cinnamic acid). In this case no significant carboxyl enhancement was observed, so we suggest that adsorbed species lie parallel to the surface. The two types of adsorption can be related to the dissociation ability of the carboxylic group. In the first case the carboxylic H dissociates, while in the second case it does not, as indicated also by the characteristic νCO band at 1686cm-1 in the FT-Raman spectra of methanolic solutions.

AB - The strength and geometry of adsorption of substituted propenoic acids on silver surface were studied by means of surface enhanced Raman spectroscopy (SERS) using silver sol. Based on their SERS behavior, two classes of phenylpropenoic acids studied were distinguished. The first class of propenoic acids (atropic acid, (E)-2,3-diphenylpropenoic acid, (E)-2-(2-methoxyphenyl)-3-phenylpropenoic acid, (E)-2,3-di-(4-methoxyphenyl)phenylpropenoic acid and (E)-2-(2-methoxyphenyl)-3-(4-fluorophenyl)propenoic acid) has shown strong charge transfer (CT) effect. We suggest bidentate carboxyl bonded species based on the SERS enhanced bands of νCOO- around 1394cm-1 and νC-C of the -C-COO- moiety at 951cm-1. In these series the plane of the α-phenyl group (γCH out-of-plane vibrations at 850-700cm-1) is almost parallel to the silver surface, while the β-phenyl group is in tilted position depending on the type and the position of substituent(s) showing strong SERS enhanced bands of νCC+βCH (in-plane mode) at 1075cm-1, νCC (ring breathing mode, in-plane) at 1000cm-1 and γCCC (out-of-plane mode) around 401cm-1. The other class of propenoic acids (cinnamic acid, (E)-2-phenyl-3-(4-methoxyphenyl)propenoic acid) has shown weak electromagnetic (EM) enhancement (CC bands is enhanced in cinnamic acid). In this case no significant carboxyl enhancement was observed, so we suggest that adsorbed species lie parallel to the surface. The two types of adsorption can be related to the dissociation ability of the carboxylic group. In the first case the carboxylic H dissociates, while in the second case it does not, as indicated also by the characteristic νCO band at 1686cm-1 in the FT-Raman spectra of methanolic solutions.

KW - 4-hydroxy benzoic acid

KW - Adsorption geometry

KW - Enantioselective hydrogenation

KW - Phenylpropenoic acids

KW - SERS

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U2 - 10.1002/jrs.4741

DO - 10.1002/jrs.4741

M3 - Article

AN - SCOPUS:84955181912

JO - Journal of Raman Spectroscopy

JF - Journal of Raman Spectroscopy

SN - 0377-0486

ER -