Crystalline structural intermediates of a breathing metal-organic framework that functions as a luminescent sensor and gas reservoir.

A rod-packing, breathing MOF (1), with two crystalline structural intermediates (1 a and 1 b; H(2) btca = benzotriazole-5-carboxylic acid) has been investigated. An underlying net approach for analyzing possible breathing MOFs, and a set of geometric parameters that can quantitatively describe such a breathing structural feature, are suggested. The 3D luminescent MOF is a promising candidate for specific sensors with exceptional sorption capacity.

Multiview Clustering via Proximity Learning in Latent Representation Space.

Most existing multiview clustering methods are based on the original feature space. However, the feature redundancy and noise in the original feature space limit their clustering performance. Aiming at addressing this problem, some multiview clustering methods learn the latent data representation linearly, while performance may decline if the relation between the latent data representation and the original data is nonlinear. The other methods which nonlinearly learn the latent data representation usually conduct the latent representation learning and clustering separately, resulting in that the latent data representation might be not well adapted to clustering. Furthermore, none of them model the intercluster relation and intracluster correlation of data points, which limits the quality of the learned latent data representation and therefore influences the clustering performance. To solve these problems, this article proposes a novel multiview clustering method via proximity learning in latent representation space, named multiview latent proximity learning (MLPL). For one thing, MLPL learns the latent data representation in a nonlinear manner which takes the intercluster relation and intracluster correlation into consideration simultaneously. For another, through conducting the latent representation learning and consensus proximity learning simultaneously, MLPL learns a consensus proximity matrix with k connected components to output the clustering result directly. Extensive experiments are conducted on seven real-world datasets to demonstrate the effectiveness and superiority of the MLPL method compared with the state-of-the-art multiview clustering methods.

Transcriptomic and metabolomic profiling reveals the drought tolerance mechanism of Illicium difengpi (Schisandraceae).

Illicium difengpi (Schisandraceae), an endangered medicinal plant endemic to karst areas, is highly tolerant to drought and thus can be used as an ideal material for investigating adaptive mechanism to drought stress. The understanding of the drought tolerance of I. difengpi, especially at the molecular level, is lacking. In the present study, we aimed to clarify the molecular mechanism underlying drought tolerance in endemic I. difengpi plant in karst regions. The response characteristics of transcripts and changes in metabolite abundance of I. difengpi subjected to drought and rehydration were analyzed, the genes and key metabolites responsive to drought and rehydration were screened, and some important biosynthetic and secondary metabolic pathways were identified. A total of 231,784 genes and 632 metabolites were obtained from transcriptome and metabolome analyses, and most of the physiological metabolism in drought-treated I. difengpi plants recovered after rehydration. There were more upregulated genes than downregulated genes under drought and rehydration treatments, and rehydration treatment induced stable expression of 65.25% of genes, indicating that rehydration alleviated drought stress to some extent. Drought and rehydration treatment generated flavonoids, phenolic acids, flavonols, amino acids and their derivatives, as well as metabolites such as saccharides and alcohols in the leaves of I. difengpi plants, which alleviated the injury caused by excessive reactive oxygen species. The integration of transcriptome and metabolome analyses showed that, under drought stress, I. difengpi increased glutathione, flavonoids, polyamines, soluble sugars and amino acids, contributing to cell osmotic potential and antioxidant activity. The results show that the high drought tolerance and recovery after rehydration are the reasons for the normal growth of I. difengpi in karst mountain areas.

Structures of the SARS-CoV-2 spike glycoprotein and applications for novel drug development.

COVID-19 caused by SARS-CoV-2 has raised a health crisis worldwide. The high morbidity and mortality associated with COVID-19 and the lack of effective drugs or vaccines for SARS-CoV-2 emphasize the urgent need for standard treatment and prophylaxis of COVID-19. The receptor-binding domain (RBD) of the glycosylated spike protein (S protein) is capable of binding to human angiotensin-converting enzyme 2 (hACE2) and initiating membrane fusion and virus entry. Hence, it is rational to inhibit the RBD activity of the S protein by blocking the RBD interaction with hACE2, which makes the glycosylated S protein a potential target for designing and developing antiviral agents. In this study, the molecular features of the S protein of SARS-CoV-2 are highlighted, such as the structures, functions, and interactions of the S protein and ACE2. Additionally, computational tools developed for the treatment of COVID-19 are provided, for example, algorithms, databases, and relevant programs. Finally, recent advances in the novel development of antivirals against the S protein are summarized, including screening of natural products, drug repurposing and rational design. This study is expected to provide novel insights for the efficient discovery of promising drug candidates against the S protein and contribute to the development of broad-spectrum anti-coronavirus drugs to fight against SARS-CoV-2.

Solvent induced diverse dimensional coordination assemblies of cupric benzotriazole-5-carboxylate: syntheses, crystal structures, and magnetic properties.

Three cupric coordination assemblies [Cu(btca)(H(2)O)(2)] (1), [Cu(btca)(H(2)O)(3.5)](8)·16H(2)O (2), and [Cu(2.5)(btca)(1.5)(Hbtca)(0.5)(µ-Cl)(0.5)(µ(3)-OH)(H(2)O)]·H(2)O (3) have been solvothermally synthesized by cupric salts and a bifunctional ligand benzotriazole-5-carboxylic acid (H(2)btca) in different solvent medium. These complexes were structurally characterized by X-ray diffraction analyses and further identified by infrared spectra (IR), elemental analyses, powder X-ray diffraction (PXRD), and thermogravimetric analyses (TGA). Single crystal structural analysis shows that these coordination compounds assembled by the almost same reactants present diverse dimensional crystal structures, wherein 1 possesses two-dimensional (2D) layers with (4.8(2)) topology, the zero-dimensional (0D) neutral metallomacrocycle with flat octagonal geometry in 2 connects each other through hydrogen bonding to extend to be a three-dimensional (3D) nanotubular network, and 3 exhibits 3D framework with 1D honeycomb channels constructed by the strip-shaped chains containing [Cu(5)(µ(3)-OH)(2)(btca)(4)](-) pentaclusters bridging to the adjacent Cu(6)(btca)(12)(6-) cages. The diversity of these structures mainly stems from the versatile coordination modes of the anionic ligand in each compound, especially the 1,2,3-triazolate group: bidentate µ(1,2) bridging mode in 1, bidentate µ(1,3) bridging mode in 2, and tridentate µ(1,2,3) bridging mode in 3, respectively. Furthermore, the magnetic properties of 1-3 have been investigated as well.

Adaptively Weighted Multiview Proximity Learning for Clustering.

Recently, the proximity-based methods have achieved great success for multiview clustering. Nevertheless, most existing proximity-based methods take the predefined proximity matrices as input and their performance relies heavily on the quality of the predefined proximity matrices. A few multiview proximity learning (MVPL) methods have been proposed to tackle this problem but there are still some limitations, such as only emphasizing the intraview relation but overlooking the inter-view correlation, or not taking the weight differences of different views into account when considering the inter-view correlation. These limitations affect the quality of the learned proximity matrices and therefore influence the clustering performance. With the aim of breaking through these limitations simultaneously, a novel proximity learning method, called adaptively weighted MVPL (AWMVPL), is proposed. In the proposed method, both the intraview relation and the inter-view correlation are considered. Besides, when considering the inter-view correlation, the weights of different views are learned in a self-weighted scheme. Furthermore, through an adaptively weighted scheme, the information of the learned view-specific proximity matrices is integrated into a view-common cluster indicator matrix which outputs the final clustering result. Extensive experiments are conducted on several synthetic and real-world datasets to demonstrate the effectiveness and superiority of our method compared with the existing methods.

2-(2-{[2-(4-Pyridylcarbon-yl)hydrazinyl-idene]meth-yl}phen-oxy)acetic acid.

In the title compound, C(15)H(13)N(3)O(4), the pyridine and benzene rings are nearly perpendicular [dihedral angle = 84.24 (5)°]. In the crystal structure, classical O-H⋯N hydrogen bonding between the OH group of the carboxyl unit and a neighbouring pyridine ring N atom and N-H⋯O hydrogen bonding between the imine NH group and a neighbouring O atom of an acyl unit, together with complementary non-classical C-H⋯O hydrogen bonds between carboxyl O atoms and neighbouring CH groups, link the mol-ecules into a three-dimensional system.

2-(2-{[2-(2-Pyridylcarbon-yl)hydrazono]meth-yl}phen-oxy)acetic acid.

In the title compound, C(15)H(13)N(3)O(4), the pyridine and benzene rings are nearly coplanar [dihedral angle = 4.92 (12)°]. The maximum deviation from the best least-squares plane calculated for the main mol-ecular skeleton is 0.1722 (1) Šfor the carbonyl O atom. In the crystal, inter-molecular O-H⋯O hydrogen bonds connect the mol-ecules into a chain, while π-π stacking inter-actions between the pyridine and benzene rings [centroid-centroid distance = 3.9162 (8) Šand offset angle = 27.20°] complete a two-dimensional network.

Spontaneous symmetry breaking of Co(II) metal-organic frameworks from achiral precursors via asymmetrical crystallization.

The racemic conglomerate (1P-NH3 + 1M-NH3) and enantioenriched bulk samples (1P-H2O or 1M-NH3) of Co(II) metal­organic frameworks were obtained from achiral precursors under different solvothermal conditions. The bulk homochirality was generated through asymmetrical crystallization in the absence of any chiral additives confirmed by single crystal X-ray diffraction and CD spectroscopy.

Modulation of argentophilic interactions by bridging amine ligands: photoluminescence tuneable by excitation energy or temperature.

A series of Ag(I) coordination oligomers with Ag-Ag distances tuned by amine auxiliary ligands were designed and synthesized. Their dual emissions could be adjusted by changing either excitation energy or temperature. The emission assignments were clarified by both experimental and DFT evidence herein.