The π···π Stacking Interactions between Homogeneous Dimers of C₆F_<i>x</i>I_{(6–<i>x</i>)} (<i>x</i> = 0, 1, 2, 3, 4, and 5): A Comparative Study with the Halogen Bond

The π···π stacking interactions between homogeneous dimers of C₆F_<i>x</i>I_{(6–<i>x</i>)} (<i>x</i> = 0, 1, 2, 3, 4, and 5) have been investigated in detail using the state-of-the-art quantum chemistry methods. Computations clearly show that the π···π stacking interaction between the homogeneous dimer of C₆F_<i>x</i>I_{(6–<i>x</i>)} is of the dispersion type interaction. At the same time, it is interesting to find that, for the π···π stacking interactions between homogeneous dimers of C₆F_<i>x</i>I_{(6–<i>x</i>)}, the M05-2X/def2-TZVPP computations give almost the same results as the CCSD­(T)/SDD** computations. In the crystal growth and design, the formation of the π···π stacking interactions between homogeneous dimers of C₆F_<i>x</i>I_{(6–<i>x</i>)} is always accompanied by the formation of the halogen bonds. Hence, competition and cooperation of the π···π stacking interaction and the halogen bond have also been studied theoretically by using C₆F_<i>x</i>I_{(6–<i>x</i>)} and pyridine as coformers. At the M05-2X/def2-TZVPP theory level, it is found that the π···π stacking interactions in C₆F₅I···C₆F₅I and C₆F₄I₂···C₆F₄I₂ are weaker than the corresponding halogen bonds in C₆F₅I···NC₅H₅ and C₆F₄I₂···NC₅H₅, and the π···π stacking interactions in C₆FI₅···C₆FI₅ and C₆I₆···C₆I₆ are stronger than the corresponding halogen bonds in C₆FI₅···NC₅H₅ and C₆I₆···NC₅H₅, while the strengths of the π···π stacking interactions in C₆F₃I₃···C₆F₃I₃ and C₆F₂I₄···C₆F₂I₄ are similar to the corresponding halogen bonds in C₆F₃I₃···NC₅H₅ and C₆F₂I₄···NC₅H₅. However, when the π···π stacking interaction and the halogen bond coexist, we find that the formation of the halogen bond will lead to the π···π stacking interaction much stronger, and vice versa

The Nature of the Noncovalent Interactions between Benzene and C₆₀ Fullerene

Noncovalent interactions between aromatic compounds and fullerenes have received considerable attention in various fields of science and technology. Employing benzene (C₆H₆) and C₆₀ fullerene as model molecules, we theoretically explored in the present study the nature of this kind of noncovalent interaction. Our results clearly show that the π···π stacking configurations of the complex C₆H₆···C₆₀ are more strongly bound than in the C–H···π analogues, and the C–H···π interactions in the C–H···π configurations of C₆H₆···C₆₀ are not of the hydrogen bonds. According to symmetry adapted perturbation theory analyses, all of the configurations of C₆H₆···C₆₀ are dominated by dispersion forces. The percentage of the dispersion components in the overall attractive interactions for the π···π stacking configurations is smaller than the percentage of the dispersion components in the overall attractive interactions for the C–H···π configurations, whereas the percentage of the electrostatic terms in the overall attractive interactions for the π···π stacking configurations is larger than the percentage of the electrostatic terms in the overall attractive interactions for the C–H···π configurations. This is distinctly different from the case of the benzene dimer

Uncovering the Nonnegligible Mechanism of Degrading Structural Extracellular Polymeric Substances for Nitrate Removal in Psychrophilic (15 °C) Waste-Activated Sludge Fermentation

Wastewater treatment plants (WWTPs) are being challenged to operate as carbon-neutral and energy-efficient systems. The structural extracellular polymeric substances (St-EPS) in waste-activated sludge (WAS), such as alginate, were revealed to form an architectural gel matrix, hindering the psychrophilic hydrolysis and acidogenesis and its application in nitrate removal. Consequently, volatile fatty acid (VFAs) production for nitrate removal at 15 °C is demonstrated by a novel, enriched psychrophilic consortium for alginate-degrading and nitrate-removing. Both alginate lyase (EC 4.2.2.3) and oligo-alginate lyase (EC 4.2.2.26) are identified for alginate utilization by the metaproteomics analysis. A high nitrate removal rate of 7.6 (WAS as the substrate) to 13.0 (alginate as the substrate) mgN/(gVSS h) was achieved. By combining high-throughput and PacBio sequencing and metagenomics analysis, two genera of Bacteroides (69.4%) and Dysgonomons (12.8%) are revealed to enhance psychrophilic WAS fermentation. The VFAs can be utilized by denitrifiers for nitrate removal in an indirect pathway. Moreover, other genera of denitrifiers (Pseudomonas, 0.11%; and Massilla, 0.003%) can excrete alginate lyase, indicating the dual merits of St-EPS degradation and nitrate removal in the direct pathway. This work extends the application of WAS for denitrifiers, providing a new carbon-neutral and energy-efficient system in WWTPs, especially under psychrophilic conditions

Discovery of RORγ Allosteric Fluorescent Probes and Their Application: Fluorescence Polarization, Screening, and Bioimaging

Retinoic acid receptor-related orphan receptor γ (RORγ) acts as a crucial transcription factor in Th17 cells and is involved in diverse autoimmune disorders. RORγ allosteric inhibitors have gained significant research focus as a novel strategy to inhibit RORγ transcriptional activity. Leveraging the high affinity and selectivity of RORγ allosteric inhibitor MRL-871 (1), this study presents the design, synthesis, and characterization of 11 allosteric fluorescent probes. Utilizing the preferred probe 12h, we established an efficient and cost-effective fluorescence polarization-based affinity assay for screening RORγ allosteric binders. By employing virtual screening in conjunction with this assay, 10 novel RORγ allosteric inhibitors were identified. The initial SAR studies focusing on the hit compound G381-0087 are also presented. The encouraging outcomes indicate that probe 12h possesses the potential to function as a powerful tool in facilitating the exploration of RORγ allosteric inhibitors and furthering understanding of RORγ function

Discovery of RORγ Allosteric Fluorescent Probes and Their Application: Fluorescence Polarization, Screening, and Bioimaging

Retinoic acid receptor-related orphan receptor γ (RORγ) acts as a crucial transcription factor in Th17 cells and is involved in diverse autoimmune disorders. RORγ allosteric inhibitors have gained significant research focus as a novel strategy to inhibit RORγ transcriptional activity. Leveraging the high affinity and selectivity of RORγ allosteric inhibitor MRL-871 (1), this study presents the design, synthesis, and characterization of 11 allosteric fluorescent probes. Utilizing the preferred probe 12h, we established an efficient and cost-effective fluorescence polarization-based affinity assay for screening RORγ allosteric binders. By employing virtual screening in conjunction with this assay, 10 novel RORγ allosteric inhibitors were identified. The initial SAR studies focusing on the hit compound G381-0087 are also presented. The encouraging outcomes indicate that probe 12h possesses the potential to function as a powerful tool in facilitating the exploration of RORγ allosteric inhibitors and furthering understanding of RORγ function

Discovery of RORγ Allosteric Fluorescent Probes and Their Application: Fluorescence Polarization, Screening, and Bioimaging

Retinoic acid receptor-related orphan receptor γ (RORγ) acts as a crucial transcription factor in Th17 cells and is involved in diverse autoimmune disorders. RORγ allosteric inhibitors have gained significant research focus as a novel strategy to inhibit RORγ transcriptional activity. Leveraging the high affinity and selectivity of RORγ allosteric inhibitor MRL-871 (1), this study presents the design, synthesis, and characterization of 11 allosteric fluorescent probes. Utilizing the preferred probe 12h, we established an efficient and cost-effective fluorescence polarization-based affinity assay for screening RORγ allosteric binders. By employing virtual screening in conjunction with this assay, 10 novel RORγ allosteric inhibitors were identified. The initial SAR studies focusing on the hit compound G381-0087 are also presented. The encouraging outcomes indicate that probe 12h possesses the potential to function as a powerful tool in facilitating the exploration of RORγ allosteric inhibitors and furthering understanding of RORγ function