The iron(II) complexes of two structural isomers of 2-(1 H-imidazol-2-yl)diazine reveal how ligand design can be a successful strategy to control the electronic and magnetic properties of complexes by fine-tuning their ligand field. The two isomers only differ in the position of a single diazinic nitrogen atom, having either a pyrazine (Z) or a pyrimidine (M) moiety. However, [Fe(M)](ClO) is a spin-crossover complex with a spin transition at 241 K, whereas [Fe(Z)](ClO) has a stable magnetic behavior between 2 and 300 K. This is corroborated by temperature-dependent Mössbauer spectra showing the presence of a quintet and a singlet state in equilibrium. The temperature-dependent single-crystal X-ray diffraction results relate the spin-crossover observed in [Fe(M)](ClO) to changes in the bond distances and angles of the coordination sphere of iron(II), hinting at a stronger σ donation of ligand Z in comparison to ligand M. The UV/vis spectra of both complexes are solved by means of the multiconfigurational wave-function-based method CASPT2 and confirm their different spin multiplicities at room temperature, as observed in the Mössbauer spectra. Calculations show larger stabilization of the singlet state in [Fe(Z)] than in [Fe(M)], stemming from the slightly stronger ligand field of the former (506 cm in the singlet). This relatively weak effect is indeed capable of changing the spin multiplicity of the complexes and causes the appearance of the spin transition in the M complex.
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http://dx.doi.org/10.1021/acs.inorgchem.8b02278 | DOI Listing |
RSC Chem Biol
December 2024
Department of Chemistry, University of Pittsburgh Pittsburgh PA 15260 USA
We report targeted protein degradation through the site-specific recruitment of native ubiquitin ligases to a protein of interest conjugation of E3 ligase ligands. Direct comparison of degradation ability of proteins displaying the corresponding bioconjugation handle at different regions of protein surfaces was explored. We demonstrate the benefit of proximal lysine residues and investigate flexibility in linker length for the design of optimal degraders.
View Article and Find Full Text PDFArch Biochem Biophys
December 2024
Department of Pharmaceutical Sciences, School of Health Sciences and Technology, UPES Dehradun - 248007, Uttarakhand, India. Electronic address:
KRAS (Kirsten rat sarcoma viral oncogene homologue), the most common mutated protein in human cancers, is the leading cause of morbidity and mortality. Before Sotorasib (AMG-510) was approved for non-small cell lung cancer treatment in 2020, the oncogenic KRAS mutations were believed to be non-druggable. High-resolution X-ray crystal structures of GDP-bound KRAS mutants with and without inhibitor resolved.
View Article and Find Full Text PDFInt J Biol Macromol
December 2024
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China. Electronic address:
Bovine serum albumin (BSA) is one of the most abundant proteins in serum, and its high-throughput detection is still one of the current challenges. Nitrogen‑phosphorus co-doped carbon dots (CDs) were synthesized by a hydrothermal method. Adenosine monophosphate (AMP) was used as a precursor for the synthesis of CDs, providing the required carbon, nitrogen and phosphorus sources for the CDs.
View Article and Find Full Text PDFTalanta
December 2024
College of Chemistry and Chemical Engineering, Henan Key Laboratory of Function-Oriented Porous Materials, Luoyang Normal University, Luoyang, 471934, China.
An europium metal organic framework (Eu-DBPA-Phen) was synthesized using 2,5-dibromoterephthalic acid (HDBPA) and 1-10-phenanthroline (Phen) as ligands. A straightforwardc quasi-ratiometric fluorescence probe was then developed for the detection of levofloxacin (LVF) by the simplistic combination of red-emitting Eu-DBPA-Phen and the inherent blue auto-fluorescence of the target. The probe exhibits the advantages of wide linear range (0.
View Article and Find Full Text PDFEur J Med Chem
December 2024
Shanghai Engineering Research Center of Molecular Therapeutics and New Drug Development, School of Chemistry and Molecular Engineering, East China Normal University, 3663 North Zhongshan Road, Shanghai, 200062, China. Electronic address:
Targeting the biosynthetic pathway of mycolic acid is highly attractive to researchers in the field of novel anti-tubercular drug development. Pks13-TE is an essential catalytic component in the last assembling step of mycolic acid, and the co-crystal structures of the Pks13-TE-inhibitor complex provide insight into ligand recognition. Based on a structure-guided strategy, N-aryl indole derivatives were designed, synthesized, and evaluated for their antitubercular activities.
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