Functionalization of nanostructured gold substrates with chiral chromophores for SERS applications: The case of 5‐Aza[5]helicene

Zanchi, Chiara; Lucotti, Andrea; Cancogni, Damiano; Fontana, Francesca; Trusso, S.; Ossi, Paolo Maria; Tommasini, Matteo

doi:10.1002/chir.22970

Cited by 9 publications

(7 citation statements)

References 44 publications

(88 reference statements)

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“…As compared with previous SERS substrates of preformed PMs with postmodification of chiral molecules, − the current PDA/Ag substrates are much less dependent upon inherently chiral organic molecules with several novel aspects, including: (i) using chiral inorganic SiO 2 as the original chiral sources; (ii) the organic PDA components synthesized using achiral organic monomers; (iii) in situ synthesis of PMs NPs in the presence of chiral sources; and (iv) easy enantiomeric discrimination even after the removal of original chiral sources of SiO 2 .…”

Section: Resultsmentioning

confidence: 99%

“…In the past two decades, considerable attention has been paid to the construction of various chiral inorganic nanomaterials ranging from amorphous silica (SiO 2 ) with complex molecular structures to crystalline PMs with high symmetric crystal structures. − In literature, − PM nanostructures modified with inherently chiral organic entities as chiral selectors could be used to discriminate chiral organic enantiomers by SERS technique. Therefore, rational design of PM-containing systems by taking chirality into account would pave a possible way for enantiomeric differentiation by conventional Raman spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

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Polydopamine/Silver Substrates Stemmed from Chiral Silica for SERS Differentiation of Amino Acid Enantiomers

Kong

Sun

Liu

et al. 2020

ACS Appl. Mater. Interfaces

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Polydopamine (PDA) and silver (Ag) nanoparticles were first generated on chiral silica nanofibers and then detached from silica to form PDA/Ag composites. The as-obtained PDA/Ag showed surface-enhanced Raman scattering (SERS) activity but very weak circular dichroism optical activity. Interestingly, the PDA/Ag substrates could make a pair of tyrosine (or phenylalanine) enantiomers show different Raman scattering signal intensities, where the differences could reach 3 times. In contrast, PDA/Ag prepared by using racemic or achiral silica did not exhibit such discrimination performance. Therefore, this research offered a novel SERS-based enantiomeric differentiation method with the assistance of plasmonic metal-containing substrates stemmed from intrinsically chiral inorganic silica.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Polydopamine/Silver Substrates Stemmed from Chiral Silica for SERS Differentiation of Amino Acid Enantiomers

Kong

Sun

Liu

et al. 2020

ACS Appl. Mater. Interfaces

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“…In this way, the 5-pentenyl-substituted azahelicene 23 is obtained, and the double bond can be reacted to introduce different types of further functional groups. In particular, in [44], it was reacted with thioacetic acid CH3CS-OH, to obtain S- A similar approach, on the same aza [5]helicene, used 5-bromo-1-pentene as the radical precursor and the TTMSS/AIBN system to generate silicon radicals for the abstraction of bromine atom [43] to produce a pentenyl radical. In this way, the 5-pentenyl-substituted azahelicene 23 is obtained, and the double bond can be reacted to introduce different types of further functional groups.…”

Section: The Minisci Reactionmentioning

confidence: 99%

Synthesis of Functionalized Six-Membered-Ring Azahelicenes

Fontana

Bertolotti

2022

Molecules

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Functionalization, namely the introduction of side groups onto the molecular scaffold of a helicene, may have either the purpose of modifying the electronic properties of the parent helicene, e.g., by adding electron-withdrawing or electron-donating groups, or the scope of providing the helicene with a “handle”, which can be reacted to bind the molecule to another molecule or to a solid structure, such as a carbon or metal surface, or again to allow for complexation of the helicene with metal ions. The possible approaches are two-fold: the synthesis of the helicene can be performed using starting materials that already contain a side group, or the side group can be introduced after the synthesis of the parent helicene. As azahelicenes are helicenes bearing one or more nitrogen atom(s) in the molecular framework, parent azahelicenes can be functionalized on carbon atoms by exploiting the presence of the electron-withdrawing nitrogen atom. Moreover, they can be transformed into quaternary salts, whose properties are quite different from those of the parent azahelicenes in terms of the solubility and electronic properties. This review aims to provide a survey of the different synthetic methods available to attain this fascinating class of compounds.

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“…This is a representative molecule of the class of helicenes, which are π-conjugated systems consisting of ortho-fused benzene rings and have many possible applications [55]. They are characterized by inherent helical chirality, and possess interesting spectroscopic properties [56][57][58][59][60][61]. As shown in Figure 3, the trace of the α em polarizability tensor evaluated by polar on the basis of TDDFT calculations nicely match with the sign and relative magnitude of the rotatory strengths R 0k reported by Gaussian09 within the same TDDFT calculation.…”

Section: The Electric Dipole-magnetic Dipole Polarizability and Ecdmentioning

confidence: 99%

Evaluation of Molecular Polarizability and of Intensity Carrying Modes Contributions in Circular Dichroism Spectroscopies

et al. 2019

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We re-examine the theory of electronic and vibrational circular dichroism spectroscopy in terms of the formalism of frequency-dependent molecular polarizabilities. We show the link between Fermi’s gold rule in circular dichroism and the trace of the complex electric dipole–magnetic dipole polarizability. We introduce the C++ code polar to compute the molecular polarizability complex tensors from quantum chemistry outputs, thus simulating straightforwardly UV-visible absorption (UV-Vis)/electronic circular dichroism (ECD) spectra, and infrared (IR)/vibrational circular dichroism (VCD) spectra. We validate the theory and the code by referring to literature data of a large group of chiral molecules, showing the remarkable accuracy of density functional theory (DFT) methods. We anticipate the application of this methodology to the interpretation of vibrational spectra in various measurement conditions, even in presence of metal surfaces with plasmonic properties. Our theoretical developments aim, in the long run, at embedding the quantum-mechanical details of the chiroptical spectroscopic response of a molecule into the simulation of the electromagnetic field distribution at the surface of plasmonic devices. Such simulations are also instrumental to the interpretation of the experimental spectra measured from devices designed to enhance chiroptical interactions by the surface plasmon resonance of metal nanostructures.

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Functionalization of nanostructured gold substrates with chiral chromophores for SERS applications: The case of 5‐Aza[5]helicene

Cited by 9 publications

References 44 publications

Polydopamine/Silver Substrates Stemmed from Chiral Silica for SERS Differentiation of Amino Acid Enantiomers

Polydopamine/Silver Substrates Stemmed from Chiral Silica for SERS Differentiation of Amino Acid Enantiomers

Synthesis of Functionalized Six-Membered-Ring Azahelicenes

Evaluation of Molecular Polarizability and of Intensity Carrying Modes Contributions in Circular Dichroism Spectroscopies

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