Infrared Detection of a Phenylboronic Acid Terminated Alkane Thiol Monolayer on Gold Surfaces

Abstract

Polarization modulation infrared reflectance absorption spectroscopy (PM-IRRAS) and infrared reflectance absorption spectroscopy (IRRAS) have been used to characterize the formation of a self-assembled monolayer of N-(3-dihydroxyborylphenyl)-11-mercaptoundecanamide) (abbreviated PBA) on a gold surface and the subsequent binding of various sugars to the PBA adlayer through the phenylboronic acid moiety to form a phenylboronate ester. Vibrationally resonant sum frequency generation (VR-SFG) spectroscopy confirmed the ordering of the substituted phenyl groups of the PBA adlayer on the gold surface. Solution FTIR spectra and density functional theory were used to confirm the identity of the observed vibrational modes on the gold surface of PBA with and without bound sugar. The detection of the binding of glucose on the gold surface was confirmed in part by the presence of a C-O stretching mode of glucose and the observed O-H stretching mode of glucose that is shifted in position relative to the O-H stretching mode of boronic acid. An IR marker mode was also observed at 1734 cm(-1) upon the binding of glucose. Additionally, changes in the peak profile of the B-O stretching band were observed upon binding, confirming formation of a phenylboronate ester on the gold surface. The binding of mannose and lactose were also detected primarily through the IR marker mode at approximately 1736 to 1742 cm(-1) depending on the identity of the bound sugar.

DFT, FT‐Raman, FT‐IR and NMR studies of 2‐fluorophenylboronic acid

“…The assignment of these bands to O-H stretching vibrations is straightforward. In the spectra of phenylboronic acid, [30] as well as of 3 and 4-pyridineboronic acids, [18] absorption bands were observed at 3280 and 3467 cm −1 , respectively. The O-H stretching modes are observed at 3467 cm −1 in the FT-IR spectrum for the 2fpba molecule.…”

“…[29] These bands are very intense and should include also the asymmetric stretching vibrations, which for phenylboronic and pentafluorophenylboronic acids are located at 1349 and 1350 cm −1 , respectively. [18,30] Kahraman et al [29] Table 1. The symmetric ring breathing mode was usually found near 1000 cm −1 in the monosubstituted benzene ring.…”

Transiently malleable multi-healable hydrogel nanocomposites based on responsive boronic acid copolymers

“…1290 cm −1 can be assigned to the B-O stretching. 87,88 The distinctive absorption peaks (broad) at 3100-3500 cm…”

Molecular structure, vibrational spectroscopic studies and NBO analysis of the 3,5‐dichlorophenylboronic acid molecule by the density functional method

“…[32] These bands are very intense and should also include the asymmetric stretching vibrations, which are located at 1349 and 1350 cm −1 for phenylboronic and pentafluorophenylboronic acids, respectively. [24,33] Kahraman et al [32] assigned the band around 1370 cm −1 to the υ(B-O) stretching vibrations for the homo-and hetrotrinuclear boron complexes. The corresponding bands were observed at 1392 cm −1 as very strong bands in FT-IR and at 1409 cm −1 as weak bands in FT-Raman spectra of the 3,5-dcpba molecule.…”