Time-Resolved Resonance Raman Spectroscopic Studies on the Radical Anions of Menaquinone and Naphthoquinone

Balakrishnan, Gurusamy; Mohandas, P.; Umapathy, Siva

doi:10.1021/jp960568n

Cited by 55 publications

(64 citation statements)

References 35 publications

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“…27 The aromatic C-C stretching modes are found to be at 1604 and 1579 cm 1 in NQ and at 1581 and 1604 cm 1 in 2-mNQ. 28 In the present case, the ring stretching modes are observed in the region 1620-1260 cm 1 (in both nRs and SERS). The nRs and SERS bands around 1390-1350 cm 1 are assigned to ring stretching mode of NQ coupled with CH 3 deformation mode of methyl group.…”

Section: Adsorption Of 2-mnq On Silver Surface Surface-enhanced Ramansupporting

confidence: 49%

“…27 The Raman spectrum of NQ shows two wavenumbers at 1663 and 1678 cm 1 due to the C O stretching vibration. 26 Balakrishnan et al 28 observed asymmetric and symmetric C O stretching wavenumbers of NQ at 1681 and 1624 cm 1 , respectively, and in 2-mNQ at 1673 and 1669 cm 1 , respectively. 28 In the present case, nRs band at 1675 cm 1 and SERS bands at 1707 and 1671 cm 1 are assigned to the C O stretching vibration.…”

Section: Adsorption Of 2-mnq On Silver Surface Surface-enhanced Ramanmentioning

confidence: 99%

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Spectral investigations on 2‐methyl‐1,4‐naphthoquinone: solvent effects, host–guest interactions and SERS

Umadevi

Ramasubbu

Vanelle

et al. 2003

J Raman Spectroscopy

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Optical absorption and fluorescence emission spectroscopic techniques were employed to investigate the solvent effects on 2-methyl-1,4-naphthoquinone (2-mNQ) and the molecular recognition of 2-mNQ in calix(8)arene. The orientation of 2-mNQ on a silver surface was analysed by SERS. The optical absorption and fluorescence emission spectra of 2-mNQ in different solvents reveal the n → p * transition and the observed features show that the singlet excited state is more stabilized in polar protic solvents by intermolecular hydrogen bonding and in polar aprotic solvents by dipole-dipole interaction. The evidence for the formation of inclusion complexes of calix(8)arene with 2-mNQ in dichloromethane was obtained by optical absorption and fluorescence emission studies. From the observations, the existence of association of molecules is proposed and the association constant is evaluated. The orientation of 2-mNQ on a silver surface was studied by SERS measurements, and was found to be 'flat-on.'

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Section: Adsorption Of 2-mnq On Silver Surface Surface-enhanced Ramansupporting

confidence: 49%

Section: Adsorption Of 2-mnq On Silver Surface Surface-enhanced Ramanmentioning

confidence: 99%

Spectral investigations on 2‐methyl‐1,4‐naphthoquinone: solvent effects, host–guest interactions and SERS

Umadevi

Ramasubbu

Vanelle

et al. 2003

J Raman Spectroscopy

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“…43 The pump beam is the third harmonic output of a 1064 nm fundamental from a Nd:YAG laser (DCR 11, Spectra Physics). The probe beam is obtained from an optical parametric oscillator (OPO) which is pumped by the third harmonic of 1064 nm output from an Nd:YAG laser (GCR 250, Spectra Physics).…”

Section: Methodsmentioning

confidence: 99%

Time-Resolved Resonance Raman and Density Functional Studies on the Ground State and Short-Lived Intermediates of Tetrabromo-p-benzoquinone

et al. 2001

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Time-resolved resonance Raman (TR3) and density functional theoretical (DFT) studies on the photogenerated transient intermediates of tetrabromo-p-benzoquinone (bromanil) are reported. The lowest triplet excited state, radical anion, and semiquinone radical have been observed. Computed spectra and normal-coordinate analysis have been used to make assignments of the observed bands. The lowest triplet state is computed to be a π−π* excited state of 3 B g symmetry. The effect of electronic excitation on the triplet state structure is found to be more pronounced in bromanil as compared to that in p-benzoquinone. The changes in structure in the bromanil radical anion have been explained from the nodal structure of the LUMO of the ground state. The computed structure of the semiquinone radical shows that it is essentially a pentadienyl radical. Consequences of these structural changes on the observed vibrational spectra have been discussed.

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“…18 In the case of 2-mNQ this mode appears around 1670 cm 1 . 8,22 The observed bands at 1634 (nRs) and 1646 cm 1 (SERS) in our spectra are assigned to C O stretching vibrations.…”

Section: Raman Spectral Studies 2-methyl-3-chloromethyl-14-naphthoqumentioning

confidence: 58%

“…The band at 1624 cm 1 is due to quinone C C stretching vibration and the band at 1599 cm 1 is assigned to aromatic C C stretching vibration. 22 The symmetric CH 3 deformation mode occurs around 1375 cm 1 , when the methyl group is next to an aromatic ring. 18 In the present case, the nRs band at 1338 cm 1 and the SERS band at 1369 cm 1 are due to the superposition of aromatic/quinone (C-C)/ (C C) stretching vibration of NQ and symmetric CH 3 deformation mode of a methyl group.…”

Section: Raman Spectral Studies 2-methyl-3-chloromethyl-14-naphthoqumentioning

confidence: 99%

Spectral investigations on 2‐methyl‐3‐chloromethyl‐1,4‐naphthoquinone and 2,3‐bis(chloromethyl)‐1,4‐naphthoquinone under laser excitation

Umadevi

Vanelle

Terme

et al. 2003

J Raman Spectroscopy

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Solvent effects on 2-methyl-3-chloromethyl-1,4-naphthoquinone and 2,3-bis(chloromethyl)-1,4-naphthoquinone were investigated using optical absorption and fluorescence emission techniques and the orientation of 2-methyl-3-chloromethyl-1,4-naphthoquinone on a silver surface was studied by surfaceenhanced Raman scattering (SERS). The observed spectral shift and the bandwidth of the optical absorption spectrum reveal the changes in dipole moment and the solvent reorganization energy in the excited state. The observed fluorescence quantum yield influences the weak intermolecular hydrogen bond and the dipole-dipole interaction in the excited state. Fluorescence polarization measurements provide the faster rotational relaxation of 2-methyl-3-chloromethyl-1,4-naphthoquinone and 2,3-bis(chloromethyl)-1,4-naphthoquinone in the excited state. SERS studies suggest that the orientation of 2-methyl-3-chloromethyl-1,4-naphthoquinone on a silver surface is stand-on.

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Time-Resolved Resonance Raman Spectroscopic Studies on the Radical Anions of Menaquinone and Naphthoquinone

Cited by 55 publications

References 35 publications

Spectral investigations on 2‐methyl‐1,4‐naphthoquinone: solvent effects, host–guest interactions and SERS

Spectral investigations on 2‐methyl‐1,4‐naphthoquinone: solvent effects, host–guest interactions and SERS

Time-Resolved Resonance Raman and Density Functional Studies on the Ground State and Short-Lived Intermediates of Tetrabromo-p-benzoquinone

Spectral investigations on 2‐methyl‐3‐chloromethyl‐1,4‐naphthoquinone and 2,3‐bis(chloromethyl)‐1,4‐naphthoquinone under laser excitation

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