Infrared spectroscopy (IR) and quantum chemistry calculations that are based on the density functional theory (DFT) have been used to study the structure and molecular interactions of the nematic and twist-bend phases of thioether-linked dimers. Infrared absorbance measurements were conducted in a polarized beam for a homogeneously aligned sample in order to obtain more details about the orientation of the vibrational transition dipole moments. The distributions to investigate the structure and conformation of the molecule dihedral angle were calculated. The calculated spectrum was compared with the experimental infrared spectra and as a result, detailed vibrational assignments are reported.
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http://dx.doi.org/10.3390/ijms23148005 | DOI Listing |
ACS Chem Biol
January 2025
Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States.
OaPAC, the photoactivated adenylyl cyclase from , is composed of a blue light using FAD (BLUF) domain fused to an adenylate cyclase (AC) domain. Since both the BLUF and AC domains are part of the same protein, OaPAC is a model for understanding how the ultrafast modulation of the chromophore binding pocket caused by photoexcitation results in the activation of the output domain on the μs-s time scale. In the present work, we use unnatural amino acid mutagenesis to identify specific sites in the protein that are involved in transducing the signal from the FAD binding site to the ATP binding site.
View Article and Find Full Text PDFJ Phys Chem B
January 2025
Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
Intermolecular hydrogen bonds between carboxyl (COO) and amino groups are a common weak interaction in proteins. Infrared (IR) spectral assignment of such an intermolecular hydrogen bond provides a fingerprint for studying protein-protein interactions as its absorption frequency is affected by the molecular electrostatic environment. Temperature-dependent FTIR and temperature-jump time-resolved IR absorbance difference spectra of several typical amino acids and those of wild type and single-site mutated αB-crystallin were performed.
View Article and Find Full Text PDFNatl Sci Rev
February 2025
Institutes of Physical Science and Information Technology, School of Chemistry & Chemical Engineering; Engineering Research Center of Autonomous Unmanned System Technology (Ministry of Education), Anhui Provincial Engineering Research Center for Unmanned System and Intelligent Technology, School of Artificial Intelligence, Anhui University, Hefei 230601, China.
Tracking atomic structural evolution along chemical transformation pathways is essential for optimizing chemical transitions and enhancing control. However, molecule-level knowledge of structural rearrangements during chemical processes remains a great challenge. Here, we couple infrared spectroscopy as a non-invasive method to probe molecular transformations, with a machine-learned protocol to immediately map the spectroscopic fingerprints to atomistic structures.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
January 2025
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, 200241, China.
Near-infrared (NIR) triplet dyes are the cornerstones of cutting-edge biomedical and material applications. The difficulty in rational development of triplet dyes increases exponentially as the absorption wavelength shifts deeper into the NIR range. Although classical H-/J-typed packing of NIR dyes has the potential to enhance intersystem crossing (ISC) compared with that in single-chromophore dyes, the triplet state quantum yields remain limited in such strategy.
View Article and Find Full Text PDFJ Med Chem
January 2025
Department of Radiopharmaceuticals, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China.
Intraoperative fluorescence navigation can illuminate the tumor, directing surgeons to accurately achieve negative margins, which not only reduces recurrence but also minimizes the incidence of complications. Herein, we developed two near-infrared fluorescent probes (Em = 820 nm) and (Em = 823 nm) with prolonged tumor retention (>72 h) and high target-to-background ratios (up to 4.5) based on the conjugation of pan-cancer targeted fibroblast activation protein inhibitor (FAPI) and the "tumor-seeking" Cyanine 7 bearing a meso-chloride and a cyclohexenyl skeleton (Cy7-Cl).
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