Experimental and calculated infrared spectra of disubstituted naphthoquinones

Agarwala, Neva; Rohani, Leyla; Hastings, Gary

doi:10.1016/j.saa.2021.120674

Cited by 7 publications

(5 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Incidentally, the calculated data in Fig. 5 is similar to that from DFT calculations for neutral isolated quinones in THF [39]. For neutral PhQ in THF, calculations indicate that the normal mode composition of the band near 1300 cm −1 is 10% 𝑣( ) a and 39% 𝑣( ) q .…”

Section: Vibrational Modes Of Neutral Phqsupporting

confidence: 70%

“…Experimental FTIR absorption spectra of PhQ/2MNQ/2ClNQ/2BrNQ/Cl 2 NQ/ Br 2 NQ in THF, in the 1400-1200 cm -1 region. These spectra have been presented previously covering a broader spectral range [39].…”

Section: Discussionmentioning

confidence: 99%

“…DFT − based molecular geometry optimization and harmonic normal − mode vibrational frequency calculations were undertaken as described previously [45], using Gaussian16 software (Gaussian Inc. Asymmetric H − bonded quinone models were constructed starting from the 2.5 Å X − ray crystal structure of PSI from T. elongatus. To construct this model for the incorporated NQs, PhQ in the A 1A binding site was modi ed without altering the position and orientation of the quinonic ring atoms.…”

Section: Ftir Spectroscopymentioning

confidence: 99%

“…As previously, we will call this model the "Q + Leu" model. Calculations for the neutral quinones in THF have also previously been undertaken [39]. For the monosubstituted NQs in PSI there are two potential orientations for the bound quinone, one where the Cl or Br atom is next to the H-bonded C = O group, or one where the H atom is next to the H-bonded C = O group.…”

Section: Trss Ftir Ds and Dds For Psi With Different Nqs Incorporatedmentioning

confidence: 99%

See 3 more Smart Citations

Time-resolved FTIR difference spectroscopy for the study of photosystem I with high potential naphthoquinones incorporated into the A1 binding site 2: Identification of neutral state quinone bands

Agarwala

Hastings

2023

Photosynth Res

View full text Add to dashboard Cite

Time-resolved step-scan FTIR difference spectroscopy at 77 K has been used to study cyanobacterial photosystem I (PSI) from Synechocystis sp. PCC 6803 with four high-potential, 1,4-naphthoquinones (NQs) incorporated into the A 1 binding site. The incorporated quinones are 2-chloro-NQ (2ClNQ), 2bromo-NQ (2BrNQ), 2,3-dichloro-NQ (Cl 2 NQ), and 2,3-dibromo-NQ (Br 2 NQ). For completeness 2methyl-NQ (2MNQ) was also incorporated and studied. Here we focus on spectra in the previously unexplored 1400 − 1200 cm − 1 spectral region. In this region several bands are identi ed and assigned to the neutral state of the incorporated quinones. This is important as identi cation of neutral state quinone bands in the regular 1700 − 1600 cm − 1 region has proven di cult in the past.For neutral PhQ in PSI a broad, intense band appears at 1300 cm − 1 . For the symmetric di-substituted NQs (Cl 2 NQ/Br 2 NQ) a single intense neutral state band is found at ~ 1280/1269 cm − 1 , respectively. For both mono-substituted NQs, 2ClNQ and 2BrNQ, however, two neutral state bands are observed near 1280 and 1250 cm − 1 , respectively. These observations from time-resolved spectra agree well with conclusions drawn from absorption spectra of the NQs in THF, which are also presented here. Density functional theory (DFT) based vibrational frequency calculations are also undertaken allowing an identi cation of the normal modes associated with the neutral state quinone bands.Multiple types of double difference spectra are compared and it is shown that this comparison is a potent approach for band identi cation in highly convoluted spectra.

show abstract

Section: Vibrational Modes Of Neutral Phqsupporting

confidence: 70%

Section: Discussionmentioning

confidence: 99%

Section: Ftir Spectroscopymentioning

confidence: 99%

Section: Trss Ftir Ds and Dds For Psi With Different Nqs Incorporatedmentioning

confidence: 99%

See 2 more Smart Citations

Time-resolved FTIR difference spectroscopy for the study of photosystem I with high potential naphthoquinones incorporated into the A1 binding site 2: Identification of neutral state quinone bands

Agarwala

Hastings

2023

Photosynth Res

View full text Add to dashboard Cite

show abstract

“…Nevertheless, the advantage of this method is that it helps identify only the changes occurring within the sample, considering both existing bands and appearance of new bands, facilitating the interpretation (Parry et al, 1991;Grdadolnik, 2003;Lorenz-Fonfria, 2020;Huix-Rotllant et al, 2021). Such type of dataanalysis is commonly used in the study of complex samples such as peptides and proteins (Demchenko, 1986;Hellwig et al, 1998;Alhazmi, 2019;Lorenz-Fonfria, 2020;Huix-Rotllant et al, 2021), and it has proven to be a valuable method that has been applied to other areas of study as e.g., photolysis of organic molecules (Agarwala et al, 2022;Lin et al, 2022), and carbon fiber production (Shimada et al, 1986).…”

Section: Introductionmentioning

confidence: 99%