A molecular sheaf: doubly threaded [6]rotaxane.

We report that the use of a hydrogen-bonded pyrimidine-macrocycle complex can efficiently facilitate the threading of two bispyridinium ethylenes into four rings, as evidenced by X-ray crystallography of its precursor, offering a rare example of a doubly threaded [6]rotaxane in 91% yield. The unusual architecture is found to be stable with no dethreading despite the large ring size of the macrocycle with respect to the stopper.

IronIII-catalyzed asymmetric inverse-electron-demand hetero-Diels-Alder reaction of dioxopyrrolidines with simple olefins.

The asymmetric catalytic inverse-electron-demand hetero-Diels-Alder reaction of dioxopyrrolidines with a variety of simple olefins has been accomplished, significantly expanding the applicability of this cyclization to both cyclic hetero-dienes and dienophiles. A new type of strong Lewis acid catalyst of ferric salt enables the LUMO activation of dioxopyrrolidines via formation of cationic species, this method yields a range of bicyclic dihydropyran derivatives with exceptional outcomes, including high yields (up to 99%), diastereoselectivity (up to 99 : 1) and enantioselectivity (up to 99% ee) under mild conditions. This facile protocol was available for the late-stage modification of several bioactive molecules and transformation into macrocycle molecules as well. The origins of enantioselectivity were elucidated based on control experiments.

Enantioselective sulfonylation to construct 3-sulfonylated oxindoles.

Asymmetric synthesis of 3-sulfonylated 3-substituted oxindoles through the addition of sodium sulfinate salts to 3-bromo-3-substituted oxindoles has been achieved using chiral nickel complexes of N,N'-dioxides. This method facilitates the creation of diverse chiral sulfonyl oxindoles, several of which display promising anticancer properties. Notably, the catalyst demonstrates remarkable tolerance to water, crucial for maintaining enantioselectivity. Furthermore, the utilization of topographic steric maps of the catalysts offers valuable insights into the mechanism underlying enantioselection reversal.

Unearthing Superior Inorganic UV Second-Order Nonlinear Optical Materials: A Mineral-Inspired Method Integrating First-Principles High-Throughput Screening and Crystal Engineering.

Natural minerals, with their adaptable framework structures exemplified by perovskite and lyonsite, have sparked substantial interest as potential templates for the design of advanced functional solid-state materials. Nonetheless, the quest for new materials with desired properties remains a substantial challenge, primarily due to the scarcity of effective and practical synthetic approaches. In this study, we have harnessed a synergistic approach that seamlessly integrates first-principles high-throughput screening and crystal engineering to reinvigorate the often-overlooked fresnoite mineral, Ba2 TiOSi2 O7 . This innovative strategy has culminated in the successful synthesis of two superior inorganic UV nonlinear optical materials, namely Rb2 TeOP2 O7 and Rb2 SbFP2 O7 . Notably, Rb2 SbFP2 O7 demonstrates a comprehensive enhancement in nonlinear optical performance, featuring a shortened UV absorption edge (260 nm) and a more robust second-harmonic generation response (5.1×KDP). Particularly striking is its significantly increased birefringence (0.15@546 nm), which is approximately 30 times higher than the prototype Ba2 TiOSi2 O7 (0.005@546 nm). Our research has not only revitalized the potential of the fresnoite mineral for the development of new high-performance UV nonlinear optical materials but has also provided a clearly defined roadmap for the efficient exploration of novel structure-driven functional materials with targeted properties.

Na4Sn4(C2O4)3F6 and NaSnC2O4F·H2O: two tin(II) fluoride oxalates display large birefringence.

Birefringent materials play an important role in laser techniques as an essential part of optical devices. Therefore, the exploration of high-performance birefringent materials has been a central focus of researchers. Herein, two tin(II) fluoride oxalates Na4Sn4(C2O4)3F6 and NaSnC2O4F·H2O were gained by the combination of birefringence-active groups of Sn2+ with stereochemically active lone pairs and planar π-conjugated [C2O4]2- groups. These groups assemble into low-dimensional structures of 0D [C2O4F4]6- clusters and 1D [SnC2O4F]∞- chains in Na4Sn4(C2O4)3F6, and double [Sn2(C2O4)2F2]∞2- chains in NaSnC2O4F·H2O, which gives rise to the large birefringence of 0.160@546 nm and 0.189@546 nm, respectively. Detailed structure-property analysis and theoretical calculations indicate that strong optical anisotropy can be induced by the rational arrangement of the Sn2+-polyhedra and [C2O4]2- groups.

Mg(C3 O4 H2 )(H2 O)2 : A New Ultraviolet Nonlinear Optical Material Derived from KBe2 BO3 F2 with High Performance and Excellent Water-Resistance.

Acquiring high-performance ultraviolet (UV) nonlinear optical (NLO) materials that simultaneously exhibit a strong second harmonic generation (SHG) coefficients, as short as possible SHG phase-matching (PM) wavelength and non-hygroscopic properties has consistently posed a significant challenge. Herein, through multicomponent modification of KBe2 BO3 F2 (KBBF), an excellent UV NLO crystal, Mg(C3 O4 H2 )(H2 O)2 , was successfully synthesized in malonic system. This material possesses a unique 2D NLO-favorable electroneutral [Mg(C3 O4 H2 )3 (H2 O)2 ]∞ layer, resulting in the rare coexistence of a strong SHG response of 3×KDP (@1064 nm) and short PM wavelength of 200 nm. More importantly, it exhibits exceptional water resistance, which is rare among ionic organic NLO crystals. Theoretical calculations revealed that its excellent water-resistant may be originated from its small available cavity volumes, which is similar to the famous LiB3 O5 (LBO). Therefore, excellent NLO properties and stability against air and moisture indicate it should be a promising UV NLO crystal.

Computer-aided accurate calculation of interacted volumes for 3D isosurface point clouds of molecular electrostatic potential.

The quality of chiral environment (i.e. catalytic pocket) is directly related to the performance of chiral catalysts. The existing methods need super computing power and time, i.e., it is difficult to quickly judge the interaction between chiral catalysts and substrates for accurately evaluating the effects of chiral catalytic pockets. In this paper, for the 3D isosurface point clouds of molecular electrostatic potential, by using computer simulations, we propose a robust method to detect interacted points, and then accurately have the corresponding interacted volumes. First, by using the existing marching cubes algorithm, we construct the 3D models with triangular surface for isosurface point clouds of molecular electrostatic potentials. Second, by using our improved hierarchical bounding boxes algorithm, we significantly filter out most redundant non-collision points. Third, by using the normal vectors of the remaining points and related triangles, we robustly determine the interacted points to construct interacted sets. And finally, by combining the classical slicing with our multi-contour segmenting, we accurately calculate the interacted volumes. Over three groups of the point clouds of the chemical molecules, experimental results show that our method effectively removes the non-interacted points at average rates of 71.65%, 77.76%, and 71.82%, and calculates the interacted volumes with the average relative errors of 1.7%, 1.6%, and 1.9%, respectively.

K(NH4)Zn2(PO4)2: a Beryllium-Free Sr2Be2B2O7 Derivative with Enhanced Interlayer Connectivity.

A novel zinc phosphate derivative of Sr2Be2B2O7 (SBBO), K(NH4)Zn2(PO4)2 (KNZP), featuring [Zn2P2O8]∞2- double layers akin to the [Be2B2O7]∞4- layers in SBBO, was successfully synthesized via a moderate hydrothermal method. Through the substitution of BeO4 and BO3 with ZnO4 and PO4, the issue of toxicity has been effectively resolved, while the enhanced interlayer interactions facilitated by covalent and hydrogen bonding in KNZP overcome the inherent structural instability. Notably, KNZP exhibits a wide transparent window and a moderate second-harmonic generation (SHG) intensity, reaching 0.7 times that of KH2PO4 (KDP), rendering it type-I phase-matchable, indicating that it is a promising UV nonlinear optical (NLO) material.

A2Hgx(SeO3)y (A = K, Rb, Cs): Three Alkali Metal Mercury Selenites Featuring Unique 1D [HgOm(SeO3)n]∞ Chains.

Herein, three alkali metal mercury selenites, K2Hg2(SeO3)3, Rb2Hg2(SeO3)3, and Cs2Hg3(SeO3)4, were successfully obtained by a hydrothermal method. The three compounds featured same one-dimensional (1D) [HgOm(SeO3)n]∞ chain structure that consisting of distorted Hg-O polyhedra and SeO3 triangular pyramids with stereochemically active lone pair (SCALP) electrons. Interestingly, the rich coordination environment of Hg atoms and the size difference of alkali metal cations lead to diverse arrangement of SeO3 groups, which makes them exhibit different birefringence. The band gaps of the three compounds indicate that they are potential ultraviolet (UV) optical materials. Detailed theoretical calculations demonstrate that the combined effects of SeO3 triangular pyramids and Hg-O polyhedra are responsible for the optical characteristics of the reported compounds.

Effects of LED Light Colors on the Growth Performance, Intestinal Morphology, Cecal Short-Chain Fatty Acid Concentrations and Microbiota in Broilers.

This study aimed to explore the effects of light-emitting diode (LED) light colors on growth, intestinal morphology, and cecal microbiota in broilers. A total of 360 healthy male Arbor Acres (AA) broilers with similar weights were selected and divided into four groups with six replicates in each group and 15 broilers in each replicate: LED white light (W), LED green light (G), LED blue light (B), and LED blue-green composite light (BG). The experimental period was 42 d, the light cycle of each treatment group was 23L:1D (23 h of light, one hour of darkness) from 1 to 3 d, and the light cycle from 4 to 42 d was 16L:8D; light intensity was 20 Lux. The results showed that the average daily feed intake and final weight of broilers receiving the B group were the highest in 21 d and 42 d compared with other groups. The average daily feed intake of the BG group was lower than that of the B group. In the same light color, small intestine villus height grows with age. On days 21 and 42, compared with other groups, the ileal villus height was higher, the crypt depth was lower, and the V/C ratio (villus to crypt ratio) was higher in the BG group. The combination of blue-green composite light was beneficial to increase the content of propionate, isobutyrate, butyrate, isovalerate, and valerate in the cecum of 21-day-old broilers and the content of isobutyrate in the cecum of 42-day-old broilers, and a decrease in cecal short-chain fatty acid concentrations with age. The B group and the BG group had higher abundances of Bacteroidetes at day 21 of age and lower abundances of Phascolarctobacterium at day 42. However, no cecal microbiota differences were detected by the Bonferroni-corrected test. In general, our research results showed that light color could promote the growth of broilers by affecting intestinal morphology, microbiota abundance (needs to be validated by further experiments), and cecal short-chain fatty acid concentrations. And blue and blue-green composite lights are more suitable for broiler growth.

Enantioselective Construction of C4-Quaternary Quinolinones via Copper(II)-Catalyzed Asymmetric [1,3] O-to-C Rearrangement.

An efficient asymmetric [1,3] O-to-C rearrangement of quinolin-2(1H)-ones enabled by a chiral bisoxazoline/copper complex has been developed. This strategy tolerated a wide range of substrates to provide a series of 1,4-dihydroquinoline-2,3-diones containing a quaternary stereocenter. A further cyclization of the [1,3] O-to-C rearrangement products was also realized, which led to various optically active 3,4-dihydroquinolin-2-ones with broad substrate scope.

Asymmetric Formal Coupling of ß-Ketoesters with Quinones Promoted by a Chiral Bifunctional N-Heterocyclic Olefin.

A highly enantioselective formal coupling of ß-ketoesters with quinones was accomplished by a chiral bifunctional N-heterocyclic olefin organocatalyst. With as low as 1 mol % catalyst loading, a number of enantioenriched quinone derivatives were afforded in good yields with high enantioselectivities and regioselectivities (up to 96% yield, 98% ee, and 19:1 rr). Gram-scale synthesis and the high inhibitory effect of several products on the viability of cancer cells demonstrate the potential utility of the current method.

Silylacylation of Alkenes through N-Heterocyclic Carbene Catalysis.

The construction of silicon-containing molecules has received increasing attention in recent years. Herein, we report the generation of silyl radicals through NHC catalysis under mild reaction conditions. This methodology offers a novel and convenient route to a diverse range of ß-silyl ketones with a broad substrate scope and good functional group compatibility. Both the radical clock and electrochemical studies are consistent with the hypothesis of ground-state SET, and a plausible mechanism for the organocatalytic transformation is proposed.

Visible-light-induced chemo-, diastereo- and enantioselective α-C(sp3)-H functionalization of alkyl silanes.

A catalytic asymmetric α-C(sp3)-H functionalization of alkyl silanes with benzosultams was realized by merging photoredox and chiral Lewis acid catalysis. The key to success was the choice of photocatalyst with an appropriate redox potential and non-nucleophilic solvent, providing a novel entry to chiral organosilanes containing two adjacent tri- and tetra-substituted stereocenters with high to efficient diastereo- and enantioselectivity (up to 99% ee, 94 : 6 dr) under mild reaction conditions. Based on the control experiment and spectral analysis, an initial single electron transfer reduction of a benzosultam-triggered simultaneous or stepwise electron transfer/proton transfer process was proposed to rationalize the favored C(sp3)-H functionalization rather than desilylation.

Cs2Mg(H2C3N3S3)4·8H2O: An Excellent Birefringent Material with Giant Optical Anisotropy in π-Conjugated Trithiocyanurate.

The design of giant birefringence was performed by adjusting cations to make parallel and compact alignments of π-conjugated (HxC3N3S3)x-3, where x = 1 and 2) groups with large polarizability anisotropy. Finally, the first mixed alkali/alkali-earth-metal trithiocyanurates, A2B(H2C3N3S3)4·nH2O (A = K, Rb, Cs; B = Mg, Sr; n = 5-8, 12), were designed and synthesized successfully. Importantly, Cs2Mg(H2C3N3S3)4·8H2O (III) and K2Sr(H2C3N3S3)4·5H2O (IV) possess large birefringences of 0.580 and 0.194 at 800 nm, respectively, of III has the largest birefringence among all practical birefringent crystals, cyanurates, and hydroisocyanurates.

Diastereodivergent Synthesis of Pentacyclic Spiroindolines via a Magnesium(II)-Catalyzed Cascade Reaction of N,N'-Cyclic Azomethine Imines with Indolyl-Substituted Isocyanides.

Magnesium(II)-catalyzed cascade reactions of N,N'-cyclic azomethine imines with indolyl-substituted isocyanides are reported herein. The method exhibited a high functional group tolerance and broad substrate scope. A series of anti-pentacyclic spiroindolines containing N,N'-fused heterocycle skeletons were obtained in up to 82% yield with 8.5:1 dr under mild reaction conditions. Intriguingly, a sequential HOAc-mediated protonation results in a diastereoenriched epimerization, which gives rise to the syn-pentacyclic spiroindolines as the sole isomers.

Hg3(SeO3)2(SO4): A UV Nonlinear Optical Mercury Selenite Sulfate Constructed by Neat [Hg6O8(SeO3)4]∞ Layers and SO4 Tetrahedra.

A novel mercury selenite sulfate named Hg3(SeO3)2(SO4) has been successfully synthesized under a mild hydrothermal method. Hg3(SeO3)2(SO4) crystallizes in a monoclinic space group P21 and features a unique three-dimensional (3D) frame structure formed by [Hg6O8(SeO3)4]∞ layers and SO4 tetrahedra, which enables it to exhibit a comprehensive performance of a moderate second-harmonic generation (SHG) response of approximately 1.3 times that of baseline KH2PO4 (KDP), a moderate birefringence (0.118@546 nm), and a wide band gap (4.70 eV), which indicates that it has potential for application as an ultraviolet (UV) nonlinear optical material. Detailed theoretical calculations show that the Hg2+-based polyhedra with large polarizability and deformability and the SeO3 groups with stereochemically active lone pair (SCALP) electrons are the main contributors to moderate optical properties.

Structural Basis of the Transcriptional Elongation Factor Paf1 Core Complex from Saccharomyces eubayanus.

The multicomponent polymerase associated factor 1 (Paf1) complex (PAF1C) is an important transcription elongation factor that upregulates RNA polymerase II-mediated genome-wide transcription. PAF1C can regulate transcription through direct association with the polymerase or by impacting the chromatin structure epigenetically. In recent years, significant progress has been made in understanding the molecular mechanisms of PAF1C. However, high-resolution structures that can clarify the interaction details among the components of the complex are still needed. In this study, we evaluated the structural core of the yeast PAF1C containing the four components Ctr9, Paf1, Cdc73 and Rtf1 at high resolution. We observed the interaction details among these components. In particular, we identified a new binding surface of Rtf1 on PAF1C and found that the C-terminal sequence of Rtf1 dramatically changed during evolution, which may account for its different binding affinities to PAF1C among species. Our work presents a precise model of PAF1C, which will facilitate our understanding of the molecular mechanism and the in vivo function of the yeast PAF1C.

Design of the Ionic Organic Nonlinear Optical Material NH4 [LiC3 H(CH3 )O4 ] with Ultrawide Band Gap and Moderate Birefringence.

Ionic organic crystals containing organic planar π-conjugated units has become one of the hot spots as nonlinear optical (NLO) materials. However, although this type of ionic organic NLO crystals commonly have remarkable second harmonic generation (SHG) responses, they also suffer from overlarge birefringences and relatively small band gaps that be hardly beyond 6.2 eV. Herein, a flexible π-conjugated [C3 H(CH3 )O4 ]2- unit was theoretically revealed, showing great potential for designing NLO crystals with balanced optical properties. Accordingly, through the reasonable NLO-favourable layered design, a new ionic organic material, NH4 [LiC3 H(CH3 )O4 ], was successfully obtained. As expected, it achieves not only a large SHG effect (4×KDP), but also a suitable birefringence (0.06@546 nm) and an ultrawide band gap (>6.5 eV). This study provides a new flexible π-conjugated NLO-active unit, contributing to design more ionic organic NLO materials with excellent balanced optical properties.

A convenient route to mixed cationic group 13/14/15 compounds.

The formation of novel cationic mixed main group compounds is reported revealing a chain composed of different elements of group 13, 14, and 15. Reactions of different pnictogenylboranes R2EBH2·NMe3 (E = P, R = Ph, H; E = As, R = Ph, H) with the NHC-stabilized compound IDipp·GeH2BH2OTf (1) (IDipp = 1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene) were carried out, yielding the novel cationic, mixed group 13/14/15 compounds [IDipp·GeH2BH2ER2BH2·NMe3]+ (2a E = P; R = Ph; 2b E = As; R = Ph; 3a E = P; R = H; 3b E = As; R = H) by the nucleophilic substitution of the triflate (OTf) group. The products were analysed by NMR spectroscopy and mass spectrometry and for 2a and 2b also by X-ray structure analysis. Further reactions of 1 with H2EBH2·IDipp (E = P, As) resulted in the unprecedented parent complexes [IDipp·GeH2BH2EH2BH2·IDipp][OTf] (5a E = P; 5b E = As), which were studied by X-ray structure analysis, NMR spectroscopy and mass spectrometry. Accompanying DFT computations give insight into the stability of the formed products with respect to their decomposition.