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Abstract The envelope (E) protein of the Japanese encephalitis virus (JEV) is a key protein for virus infection and adsorption of host cells, which determines the virulence of the virus and regulates the intensity of inflammatory response. The mutation of multiple aa residues in the E protein plays a critical role in the attenuated strain of JEV. This study demonstrated that the Asp to Gly, Ser, and His mutation of the E389 site, respectively, the replication ability of the viruses in cells was significantly reduced, and the viral neuroinvasiveness was attenuated to different degrees. Among them, the mutation at E389 site enhanced the E protein flexibility contributed to the attenuation of neuroinvasiveness. In contrast, less flexibility of E protein enhanced the neuroinvasiveness of the strain. Our results indicate that the mechanism of attenuation of E389 aa mutation attenuates neuroinvasiveness is related to increased flexibility of the E protein. In addition, the increased flexibility of E protein enhanced the viral sensitivity to heparin inhibition in vitro, which may lead to a decrease in the viral load entering brain. These results suggest that E389 residue is a potential site affecting JEV virulence, and the flexibility of the E protein of aa at this site plays an important role in the determination of neuroinvasiveness.

Abstract Conformational isomerism of organic photovoltaic materials has a profound impact on their molecular packing and therefore performance of polymer solar cells (PSCs). However, the conformations of oligomeric acceptors (OAs) are mostly predicted by simulations rather than experimental determinations. Herein, the stereochemical S‐shaped structure of two dimeric‐type acceptor molecules, V‐DYIC and V‐DYIC‐4F, is first confirmed with different end groups (IC for V‐DYIC and IC‐2F for V‐DYIC‐4F), incorporating vinylene linkage for connecting the distinct state‐of‐the‐art small molecule acceptor Y‐segments. Through the synthetic control of fluorination sites adjacent to the vinyl‐linker, S‐shaped the conformation by NMR experiments is validated. Compared to the O‐shaped dimer, S‐shaped conformation results in enhanced lamellar order and reduced nonradiative recombination losses. The optimal acceptor, V‐DYIC‐4F, achieved a champion efficiency of 18.10% with the lowest energy loss of 0.556 eV in its devices paired with PM6 due to their efficient carrier transport, and suppressed recombination compared to other devices, being attributed to the synergistic effect of conformation and end group fluorination. The insights gained in this work contribute valuable knowledge of both synthetic control and structural determination of OAs, providing strategic design guidelines for the future development of dimeric acceptors toward high‐efficiency PSCs.

ABSTRACTMany artificial molecular machines have been synthesized, and various functions have been expressed by changing their molecular conformations. However, their structures are still simple compared with those of biomolecular machines, and more energy is required to control them. To design artificial molecular machines with more complex structures and higher functionality, it is necessary to combine molecular machines with simple movements such as components. This means that the motion of individual molecular machines must be precisely controlled and observed in various environments. At the air – water interface, the molecular orientation and conformation can be controlled with little energy as thermal fluctuations. We designed various molecular machines and controlled them using mechanical stimuli at the air – water interface. We also controlled the transfer of forces to the molecular machines in various lipid matrices. In this review, we describe molecular pliers with amphiphilic binaphthyl, molecular paddles with binuclear platinum complexes, and molecular rotors with julolidine and BODIPY that exhibit twisted intramolecular charge transfer.

Ewing sarcoma (ES) is a highly malignant and aggressive small round-cell tumor originating from primitive neuroepithelium and mesenchymal stem cells. It is usually seen in children and adolescents with a male predilection and a preponderance to occur in long bones. Although skeletal/soft tissue ES is encountered in clinical practice, primary ES of the genital tract, particularly bilateral primary ovarian ES, is highly uncommon, with only a handful of cases reported worldwide. Ovarian ES is occasionally reported to involve para-aortic and pelvic lymph nodes in advanced stages. Still, cervical lymph node metastasis from ovarian ES is an infrequent clinical occurrence and, when present, indicates a worse prognosis. Here, we present an intriguing case of bilateral peripheral primary ovarian ES in an adult female, recurring as metastasis in the left submandibular lymph node. This case underlines the importance of keeping metastasis from ES as a possible differential while diagnosing metastatic small round cell tumors in peripheral lymph nodes. It also highlights the usefulness of a minimally invasive diagnostic modality of fine needle aspiration cytology and cell block preparation with applied ancillary techniques of immunohistochemistry and confirmatory molecular testing by fluorescence in-situ hybridization (FISH), for an accurate and quick diagnosis of such entities. The cytological diagnosis of our patient helped in the prompt and early initiation of chemotherapy without requiring any invasive procedure.

Abstract In order to improve the performance of organic luminescent materials, lots of studies have been carried out at the molecular level. However, these materials are mostly applied as solids or aggregates in practical applications, in which the relationship between aggregation structure and luminescent property should be paid more attention. Here, we obtained five phenothiazine 5,5‐dioxide (O‐PTZ) derivatives with distinct molecular conformations by rational design of chemical structures, and systematically studied their room‐temperature phosphorescence (RTP) effect in solid state. It was found that O‐PTZ dimers with quasi‐equatorial (eq) conformation tended to show stronger π‐π interaction than quasi‐axial (ax) conformers in crystal state, which was more conducive to the generation of RTP. Based on this result, a multi‐level structural model of organic solids was proposed to draw the relationship between aggregation structure and RTP effect, just like the research for the structure‐property relationship of proteins. Using this structural model as the guide, boosted RTP efficiency from 1% to 20% was successfully achieved in the corresponding host‐guest doping system, showing its wide applicability.

Abstract Background The functional properties of food fluids containing hydrocolloids are influenced by temperature, soluble salts, pH and the presence of sugars. In this research, the properties of a dilute barley β-glucan (BBG) solution were evaluated in the presence of various factors. Different models were explored to determine the intrinsic viscosity of BBG. Results The results indicated that the models of Higiro and Tanglertpaibul–Rao were more efficient in determining the intrinsic viscosity of BBG at different temperatures, different pH, the presence of sodium chloride, calcium chloride, and sucrose. Every 10 °C increase in temperature from 25 to 65 °C caused a decrease in intrinsic viscosity by 7.8, 10, 5.7 and 7.2%, respectively. In relation to the non-ionic structure of BBG, the presence of monovalent and bivalent salts had a negligible effect on reducing the intrinsic viscosity. The increase in pH from 3 to 7 caused a rise in intrinsic viscosity. But a further increase in pH, up to 9, caused a decrease in intrinsic viscosity. However, these changes were not significant and indicated that the non-ionic structure of BBG was independent of the pH. Since the constant b values of BBG were close to 1 at all temperatures, salt concentrations, different pH values and different sucrose concentrations, it can be assumed that the structure of BBG in the dilute range was close to the random coil conformation. Conclusions The values of flexibility index and activation energy for BBG were calculated as 789.52 and $${0.65\times 10}^{7}$$ 0.65 × 10 7 J/kmole, respectively, which indicated that this hydrocolloid was highly flexible in different environmental conditions and it was independent of the processing temperature. Therefore, BBG can be recommended as a natural thickener in food-related fluids. Graphical Abstract

In the age of information technology and the additional computational search tools and software available, this systematic review aimed to identify potential therapeutic targets for obesity, evaluated in silico and subsequently validated in vivo. The systematic review was initially guided by the research question “What therapeutic targets have been used in in silico analysis for the treatment of obesity?” and structured based on the acronym PECo (P, problem; E, exposure; Co, context). The systematic review protocol was formulated and registered in PROSPERO (CRD42022353808) in accordance with the Preferred Reporting Items Checklist for Systematic Review and Meta-Analysis Protocols (PRISMA-P), and the PRISMA was followed for the systematic review. The studies were selected according to the eligibility criteria, aligned with PECo, in the following databases: PubMed, ScienceDirect, Scopus, Web of Science, BVS, and EMBASE. The search strategy yielded 1142 articles, from which, based on the evaluation criteria, 12 were included in the systematic review. Only seven these articles allowed the identification of both in silico and in vivo reassessed therapeutic targets. Among these targets, five were exclusively experimental, one was exclusively theoretical, and one of the targets presented an experimental portion and a portion obtained by modeling. The predominant methodology used was molecular docking and the most studied target was Human Pancreatic Lipase (HPL) (n = 4). The lack of methodological details resulted in more than 50% of the papers being categorized with an “unclear risk of bias” across eight out of the eleven evaluated criteria. From the current systematic review, it seems evident that integrating in silico methodologies into studies of potential drug targets for the exploration of new therapeutic agents provides an important tool, given the ongoing challenges in controlling obesity.

Biofilms were obtained from cocoons of the silkworm, Bombyx mori, involving the removal of sericin, extraction and solubilization of fibroin fibers, dialysis of fibroin dispersions and preparation of biofilms by the casting process. Biofilm transparency was verified by UV–Vis spectroscopy and thermal stability by thermogravimetric/differential scanning calorimetry (TG/DSC). Soon after preparation, the solidification of the fibroin solution prepared from the cocoons and extracted by the Ajisawa method was monitored until the biofilm stabilized, using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) as a function of time. The results showed that there was a change in the conformation from the silk I structure (α-helix) to silk II (β-sheet). In order to improve the characterization of the biofilms obtained by the Ajisawa method and LiBr solubilization of fibroin fibers, Raman spectroscopy was used to verify the stabilization of the different possible molecular conformations for the fibers in these materials, by comparison with the cocoon spectra and those of the solid (freeze-dried precipitated by dialysis for 72 h. By comparing the Raman spectra of the biofilms in terms of the intensities of the broadened band characteristic of amide I, it was possible to assess the conformational changes in both materials based on the possible transitions between β-sheet conformations and flexible α-helix and β-turn structures. The results showed a dispersion of these conformations in the biofilms generated and in the solid freeze-dried hydrogel spectrum, and the β-sheet conformation was found to be predominant. The TG and DSC curves showed that the materials with higher β-sheet content exhibited higher thermal stability. Thus, the data obtained further elucidated the properties of these materials that are widely used in various processes.

Abstract Phase‐change semiconductor is one of the best candidates for designing nonvolatile memory, but it has never been realized in organic semiconductors until now. Here, a phase‐changeable and high‐mobility organic semiconductor (3,6‐DATT) is first synthesized. Benefiting from the introduction of electrostatic hydrogen bond (S···H), the molecular conformation of 3,6‐DATT crystals can be reversibly modulated by the electric field and ultraviolet irradiation. Through experimental and theoretical verification, the tiny difference in molecular conformation leads to crystalline polymorphisms and dramatically distinct charge transport properties, based on which a high‐performance organic phase‐change memory transistor (OPCMT) is constructed. The OPCMT exhibits a quick programming/erasing rate (about 3 s), long retention time (more than 2 h), and large memory window (i.e., large threshold voltage shift over 30 V). This work presents a new molecule design concept for organic semiconductors with reversible molecular conformation transition and opens a novel avenue for memory devices and other functional applications.

Ligand-based virtual screening (LBVS) is a promising approach for rapid and low-cost screening of potentially bioactive molecules in the early stage of drug discovery. Compared with traditional similarity-based machine learning methods, deep learning frameworks for LBVS can more effectively extract high-order molecule structure representations from molecular fingerprints or structures. However, the 3D conformation of a molecule largely influences its bioactivity and physical properties, and has rarely been considered in previous deep learning-based LBVS methods. Moreover, the relative bioactivity benchmark dataset is still lacking. To address these issues, we introduce a novel end-to-end deep learning architecture trained from molecular conformers for LBVS. We first extracted molecule conformers from multiple public molecular bioactivity data and consolidated them into a large-scale bioactivity benchmark dataset, which totally includes millions of endpoints and molecules corresponding to 954 targets. Then, we devised a deep learning-based LBVS called EquiVS to learn molecule representations from conformers for bioactivity prediction. Specifically, graph convolutional network (GCN) and equivariant graph neural network (EGNN) are sequentially stacked to learn high-order molecule-level and conformer-level representations, followed with attention-based deep multiple-instance learning (MIL) to aggregate these representations and then predict the potential bioactivity for the query molecule on a given target. We conducted various experiments to validate the data quality of our benchmark dataset, and confirmed EquiVS achieved better performance compared with 10 traditional machine learning or deep learning-based LBVS methods. Further ablation studies demonstrate the significant contribution of molecular conformation for bioactivity prediction, as well as the reasonability and non-redundancy of deep learning architecture in EquiVS. Finally, a model interpretation case study on CDK2 shows the potential of EquiVS in optimal conformer discovery. The overall study shows that our proposed benchmark dataset and EquiVS method have promising prospects in virtual screening applications.

Crystal structures are reported for three amides containing N-benzo[d]thiazole substituents. In N-(benzo[d]thiazol-6-yl)-3-bromobenzamide, C14H9BrN2OS, where the two ring systems are nearly parallel to one another [dihedral angle = 5.8 (2)°], the molecules are linked by N—H...O and C—H...N hydrogen bonds to form ribbons of R33(19) rings, which are linked into sheets by short Br...Br interactions [3.5812 (6) Å]. N-(6-Methoxybenzo[d]thiazol-2-yl)-2-nitrobenzamide, C15H11N3O4S, crystallizes with Z′ = 2 in space group Pna21: the dihedral angles between the ring systems [46.43 (15) and 66.35 (13)°] are significantly different in the independent molecules and a combination of two N—H...N and five C—H...O hydrogen bonds links the molecules into a three-dimensional network. The molecules of 5-cyclopropyl-N-(6-methoxybenzo[d]thiazol-2-yl)isoxazole-3-carboxamide, C15H13N3O3S, exhibit two forms of disorder, in the methoxy group and in the cyclopropylisoxazole unit; symmetry-related pairs of molecules are linked into dimers by pairwise N—H...N hydrogen bonds. Comparisons are made with the structures of some related compounds.

The compound N-[2-(4-fluoro-3-phenoxybenzoyl)hydrazinecarbothioyl]benzamide, C21H16FN3O3S, crystallizes in the monoclinic centrosymmetric space group P21/c and its molecular conformation is stabilized via an intramolecular N—H...O hydrogen bond. The corresponding para-methoxy derivative, namely, N-[2-(4-fluoro-3-phenoxybenzoyl)hydrazinecarbothioyl]-4-methoxybenzamide, C22H18FN3O4S, crystallizes in the monoclinic centrosymmetric space group C2/c. The supramolecular network mainly comprises N—H...O, N—H...S and C—H...O hydrogen bonds, which contribute towards the formation of the crystal structures for the two molecules. The different intermolecular interactions have been further analysed using Hirshfeld surface analysis and fingerprint plots.

Fifteen 4-(2-methoxyphenyl)piperazin-1-ium salts containing organic anions have been prepared and structurally characterized. In the isostructural 4-chlorobenzoate and 4-bromobenzoate salts, C11H17N2O+·C7H4ClO2− (I) and C11H17N2O+·C7H4BrO2− (II), and the 4-iodobenzoate salt C11H17N2O+·C7H4IO2− (III), the ions are linked by N—H...O hydrogen bonds, forming centrosymmetric R44(12) four-ion aggregates; a similar aggregate is formed in the 2-chlorobenzoate salt (V), isomeric with (I). In the 2-fluorobenzoate salt C11H17N2O+·C7H4FO2− (IV), and the isomorphous pair of salts, the 2-bromobenzoate (VI), isomeric with (II) and 2-iodobenzoate (VII), isomeric with (III), N—H...O and C—H...π(arene) interactions link the components into three-dimensional arrays. Four-ion R44(12) aggregates are also found in the 2-methylbenzoate, 4-aminobenzoate and 4-nitrobenzoate salts, C11H17N2O+·C8H7O2− (VIII), C11H17N2O+·C7H6NO2− (IX) and C11H17N2O+·C7H4NO4− (X), but those in (IX) are linked into complex sheets by an additional N—H...O hydrogen bond. In the 3,5-dinitrobenzoate salt, C11H17N2O+·C7H3N2O6−·2H2O (XI), N—H...O and O—H...O hydrogen bonds link the components into a complex ribbon structure. In the picrate salt, C11H17N2O+·C6H2N3O7− (XII), the four-ion aggregates are linked into chains of rings by C—H...O hydrogen bonds. In the hydrogen maleate salt, C11H17N2O+·C4H3O4− (XIII), two- and three-centre hydrogen bonds link the ions into a ribbon structure while both anions contain very short but asymmetric O—H...O hydrogen bonds, having O...O distances of 2.4447 (16) and 2.4707 (17) Å. O—H...O Hydrogen bonds link the anions in the hydrogen fumarate salt (XIV), isomeric with (XIII), into chains that are linked into sheets via N—H...O hydrogen bonds. In the hydrogen (2R,3R)-tartrate salt, C11H17N2O+·C4H5O6−·1.698H2O (XV), the anions are linked into sheets by O—H...O hydrogen bonds. Comparisons are made with the structures of some related compounds.

Two new substituted propanedioate esters have been synthesized using a three-component solvent-free thermal reaction between diethyl propanedioate (diethyl malonate), 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde and an aryl azide, forming two new C—C bonds in a single step. The products diethyl (RS)-2-[(4-bromophenyl)(5-methyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)methyl]propanedioate, C24H25BrN2O5 (I), and diethyl (RS)-2-[(4-chlorophenyl)(5-methyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)methyl]propanedioate, C24H25ClN2O5 (II), are isomorphous, with Z′ = 2 in space group P21/n. The two independent molecules in compound (I) are both fully ordered, while each of the independent molecules in compound (II) is disordered, but in different ways. In one molecule of (II), the N-phenyl ring is disordered over two sets of atomic sites having occupancies 0.635 (10) and 0.365 (10), and in the other molecule the ester function is disordered over two sets of atomic sites having occupancies 0.690 (5) and 0.310 (5). In both structures, the two independent molecules adopt different conformations and, in each structure, the molecules are linked into complex sheets by a combination of N—H...O, C—H...O and C—H...π(arene) hydrogen bonds. Comparisons are made with some related structures.

In the title salt {systematic name: 4-[6-chloro-2,9-diazatricyclo[9.4.0.03,8]pentadeca-1(15),3(8),4,6,9,11,13-heptaen-10-yl]-1-methylpiperazin-1-ium 3,5-dinitrobenzoate–3,5-dinitrobenzic acid (1/1)}, C18H20ClN4+·C7H3N2O6−·C7H4N2O6, there is a very short, asymmetric, O—H...O hydrogen bond [O...O = 2.453 (3) Å] within the anion. The oxygen atoms of one of the nitro groups of the anion are disordered over two sets of sites having occupancies of 0.56 (3) and 0.44 (3). The fused tricyclic portion of the cation adopts a butterfly conformation, with a dihedral angle of 45.59 (6)° between the planes of the two aryl rings. In the crystal, a combination of O—H...O, N—H...O and C—H...O hydrogen bonds links the component species into a three-dimensional framework. Comparisons are made with the structures of some related compounds.

In order to attain high recording density in a hard disk drive, reduction of the head-media spacing (HMS) is crucial. The contribution of lubricant thickness to the HMS is a significant factor in performance. Because the lubricant thickness is on the order of angstroms, molecules of long-chain lubricants, such as perfluoroether, must lay parallel to the magnetic disk surface to reduce lubricant thickness. In this study, new lubricants were designed using ionic liquids (ILs). The ILs had smaller molecular weight than that of current perfluoropolyether (PFPE) lubricants but with lower evaporation loss. The molecular conformation of the ILs was controlled by two hydroxyl groups, which were placed in a cation moiety at both terminal ends (IL-1) or placed on one side of the cation (IL-2). The monolayer thickness of IL-1 and IL-2 was seen to be 0.6 nm and 1.2 nm, respectively. The adhesion force at a lubricant thickness of 1.0 nm decreased in the order: PFPE (Z-Dol 2000) > IL-2 > IL-1. The small adhesion force, which is one of the essential parameters for low flight of a magnetic head, was achieved by changing the molecular conformation of the IL.

The two isomers 2′-(4-nitrobenzoyloxy)acetophenone (systematic name: 2-acetylphenyl 4-nitrobenzoate) (I) and 2′-(2-nitrobenzoyloxy)acetophenone (systematic name: 2-acetylphenyl 2-nitrobenzoate) (II), both C15H11NO5, with para and ortho positions of the nitro substituent have been crystallized and studied. It is evident that the variation in the position of the nitro group causes a significant difference in the molecular conformations: the dihedral angle between the aromatic fragments in the molecule of I is 84.80 (4)°, while that in the molecule of II is 6.12 (7)°. Diffraction analysis revealed the presence of a small amount of water in the crystal of I. DFT calculations of the molecular energy demonstrate that the ortho substituent causes a higher energy for isomer II, while crystal lattice energy calculations show that the values are almost equal for two isomers.

Three salts containing the 4-(4-fluorophenyl)piperazin-1-ium cation have been prepared and structurally characterized. In 4-(4-fluorophenyl)piperazin-1-ium 2-hydroxy-3,5-dinitrobenzoate, C10H14FN2+·C7H3N2O7−, (I), the anion contains an intramolecular O—H...O hydrogen bond, and it has a structure similar to that of the picrate ion. The cations and anions are linked into [001] chains of rings by a combination of two three-centre N—H...(O)2 hydrogen bonds. The anion in 4-(4-fluorophenyl)piperazin-1-ium hydrogen oxalate, C10H14FN2+·C2HO4−, (II), is planar, and the cations and anions are linked into (100) sheets by multiple hydrogen bonds including two-centre N—H...O, three-centre N—H...(O)2, O—H...O, C—H...O and C—H...π(arene) types. In 4-(4-fluorophenyl)piperazin-1-ium hydrogen (2R,3R)-tartrate monohydrate, C10H14FN2+·C4H5O6−·H2O, (III), the anion exhibits an approximate non-crystallographic twofold rotation symmetry with antiperiplanar carboxyl groups. A combination of eight hydrogen bonds, encompassing two- and three-centre N—H...O systems, O—H...O and C—H...π(arene) types, link the independent components into a three-dimensional framework. Comparisons are made with some related structures.

Five examples each of 3-(5-aryloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)-1-[4-(prop-2-yn-1-yloxy)phenyl]prop-2-en-1-ones and the corresponding 1-(4-azidophenyl)-3-(5-aryloxy-3-methyl-1-phenyl-1H-pyrazol-4-yl)prop-2-en-1-ones have been synthesized in a highly efficient manner, starting from a common source precursor, and structures have been determined for three examples of each type. In each of 3-[5-(2-chlorophenoxy)-3-methyl-1-phenyl-1H-pyrazol-4-yl]-1-[4-(prop-2-yn-1-yloxy)phenyl]prop-2-en-1-one, C28H21ClN2O3, (Ib), the isomeric 3-[5-(2-chlorophenoxy)-3-methyl-1-phenyl-1H-pyrazol-4-yl]-1-[4-(prop-2-yn-1-yloxy)phenyl]prop-2-en-1-one, (Ic), and 3-[3-methyl-5-(naphthalen-2-yloxy)-1-phenyl-1H-pyrazol-4-yl]-1-[4-(prop-2-ynyloxy)phenyl]prop-2-en-1-one, C32H24N2O3, (Ie), the molecules are linked into chains of rings, formed by two independent C—H...O hydrogen bonds in (Ib) and by a combination of C—H...O and C—H...π(arene) hydrogen bonds in each of (Ic) and (Ie). There are no direction-specific intermolecular interactions in the structure of 1-(4-azidophenyl)-3-[3-methyl-5-(2-methylphenoxy)-1-phenyl-1H-pyrazol-4-yl]prop-2-en-1-one, C26H21N5O2, (IIa). In 1-(4-azidophenyl)-3-[5-(2,4-dichlorophenoxy)-3-methyl-1-phenyl-1H-pyrazol-4-yl]prop-2-en-1-one, C25H17Cl2N5O2, (IId), the dichlorophenyl group is disordered over two sets of atomic sites having occupancies 0.55 (4) and 0.45 (4), and the molecules are linked by a single C—H...O hydrogen bond to form cyclic, centrosymmetric R22(20) dimers. Similar dimers are formed in 1-(4-azidophenyl)-3-[3-methyl-5-(naphthalen-2-yloxy)-1-phenyl-1H-pyrazol-4-yl]prop-2-en-1-one, C29H21N5O2, (IIe), but here the dimers are linked into a chain of rings by two independent C—H..π(arene) hydrogen bonds. Comparisons are made between the molecular conformations within both series of compounds.

Crystal structures are reported for N-(4-methoxyphenyl)piperazine (MeOPP), (I), and for its 3,5-dinitrobenzoate, 2,4,6-trinitrophenolate (picrate) and 4-aminobenzoate salts, (II)–(IV), the last of which crystallizes as a monohydrate. In MeOPP, C11H16N2O, (I), the 4-methoxyphenyl group is nearly planar and it occupies an equatorial site on the piperazine ring: the molecules are linked into simple C(10) chains by N—H...O hydrogen bonds. In each of the salts, i.e., C11H17N2O+·C7H3N2O6−, (II), C11H17N2O+·C6H2N3O7−, (III), and C11H17N2O+·C7H6NO2−·H2O, (IV), the effectively planar 4-methoxyphenyl substituent again occupies an equatorial site on the piperazine ring. In (II), two of the nitro groups are disordered over two sets of atomic sites and the bond distances in the anion indicate considerable delocalization of the negative charge over the C atoms of the ring. The ions in (II) are linked by two N—H...O hydrogen bonds to form a cyclic, centrosymmetric four-ion aggregate; those in (III) are linked by a combination of N—H...O and C—H...π(arene) hydrogen bonds to form sheets; and the components of (IV) are linked by N—H...O, O—H...O and C—H...π(arene) hydrogen bonds to form a three-dimensional framework structure. Comparisons are made with the structures of some related compounds.

Chalcones of type 4-XC6H4C(O)CH=CHC6H4(OCH2CCH)-4, where X = Cl, Br or MeO, have been converted to the corresponding 4,5-dihydropyrazole-1-carbothioamides using a cyclocondensation reaction with thiosemicarbazide. The chalcones 1-(4-chlorophenyl)-3-[4-(prop-2-ynyloxy)phenyl]prop-2-en-1-one, C18H13ClO2, (I), and 1-(4-bromophenyl)-3-[4-(prop-2-ynyloxy)phenyl]prop-2-en-1-one, C18H13BrO2, (II), are isomorphous, and their molecules are linked into sheets by two independent C—H...π(arene) interactions, both involving the same aryl ring with one C—H donor approaching each face. In each of the products (RS)-3-(4-chlorophenyl)-5-[4-(prop-2-ynyloxy)phenyl]-4,5-dihydropyrazole-1-carbothioamide, C19H16ClN3OS, (IV), (RS)-3-(4-bromophenyl)-5-[4-(prop-2-ynyloxy)phenyl]-4,5-dihydropyrazole-1-carbothioamide, C19H16BrN3OS, (V), and (RS)-3-(4-methoxyphenyl)-5-[4-(prop-2-ynyloxy)phenyl]-4,5-dihydropyrazole-1-carbothioamide, C20H19N3O2S, (VI), the reduced pyrazole ring adopts an envelope conformation with the C atom bearing the 4-prop-2-ynyloxy)phenyl substituent, which occupies the axial site, displaced from the plane of the four ring atoms. Compounds (IV) and (V) are isomorphous and their molecules are linked into chains of edge-fused rings by a combination of N—H...S and C—H...S hydrogen bonds. The molecules of (VI) are linked into sheets by a combination of N—H...S, N—H...N and C—H...π(arene) hydrogen bonds. Comparisons are made with the structures of some related compounds.

Two new chalcones containing both pyrazole and thiophene substituents have been prepared and structurally characterized. 3-(3-Methyl-5-phenoxy-1-phenyl-1H-pyrazol-4-yl)-1-(thiophen-2-yl)prop-2-en-1-one, C23H18N2O2S (I), and 3-[3-methyl-5-(2-methylphenoxy)-1-phenyl-1H-pyrazol-4-yl]-1-(thiophen-2-yl)prop-2-en-1-one, C24H20N2O2S (II), are isomorphous as well as isostructural, and in each the thiophene substituent is disordered over two sets of atomic sites having occupancies 0.844 (3) and 0.156 (3) in (I), and 0.883 (2) and 0.117 (2) in (II). In each structure, the molecules are linked into sheets by a combination of C—H...N and C—H...O hydrogen bonds. Comparisons are made with some related compounds.

Three title compounds, namely, 2-(4-chlorobenzyl)-5-[(1H-indol-3-yl)methyl]-6-phenylimidazo[2,1-b][1,3,4]thiadiazole, C26H19ClN4S, (I), 2-(4-chlorobenzyl)-6-(4-fluorophenyl)-5-[(1H-indol-3-yl)methyl]imidazo[2,1-b][1,3,4]thiadiazole, C26H18ClFN4S, (II), and 6-(4-bromophenyl)-2-(4-chlorobenzyl)-5-[(1H-indol-3-yl)methyl]imidazo[2,1-b][1,3,4]thiadiazole, C26H18BrClN4S, (III), have been prepared using a reductive condensation of indole with the corresponding 6-aryl-2-(4-chlorobenzyl)imidazo[2,1-b][1,3,4]thiadiazole-5-carbaldehydes (aryl = phenyl, 4-fluorophenyl or 4-bromophenyl), and their crystal structures have been determined. The asymmetric unit of compound (I) consists of two independent molecules and one of the molecules exhibits disorder of the 4-chlorobenzyl substituent with occupancies 0.6289 (17) and 0.3711 (17). Each type of molecule forms a C(8) chain motif built from N—H...N hydrogen bonds, which for the fully ordered molecule is reinforced by C—H...π interactions. In compound (II), the chlorobenzyl unit is again disordered, with occupancies 0.822 (6) and 0.178 (6), and the molecules form C(8) chains similar to those in (I), reinforced by C—H...π interactions involving only the major disorder component. The chlorobenzyl unit in compound (III) is also disordered with occupancies of 0.839 (5) and 0.161 (5). The molecules are linked by a combination of one N—H...N hydrogen bond and four C—H...π interactions, forming a three-dimensional framework.

In this study raw and processed silkworm (Bombyx mori) cocoons were investigated using confocal Raman spectroscopy in conjunction with differential scanning calorimetry (DSC) in order to examine the effect of temperature on the molecular conformation of silk fiber structures. Using DSC, a broad endothermic curve was observed at moderate temperatures, shedding light on the vaporization of both raw and processed cocoons, a phenomenon that could also indicate a strong interaction between silk fibroin and water molecules. Over the temperature range set for this study, Raman spectra of raw and processed cocoons were compared at different excitation radiations after drying both kinds of cocoon in an oven at 80 and 125 ºC for 60 minutes. By correlating the intensity ratios of the deconvoluted Raman bands using the broad bands characteristic of amide I and III, it was possible to evaluate the conformational changes in both materials. At excitation radiation of 532 nm, the deconvoluted Raman spectra for the amide III band indicated that, for both samples, there was a reduction in β-sheet conformation compared to α-helix conformation, and this structural disruption was driven by increased temperature. At radiation of 785 nm, the bands attributed to amino acid residues in the side chains increased in intensity, and by deconvoluting the amide I band, increased temperature was found to induce a transition from β-sheets to β-turns in both materials.

Since strong polarity usually causes emission quenching, materials with polarity-induced emission (PIE) are rarely reported despite their important applications in polar environments. Herein, an N-phenylcarbazole-substituted benzophenone derivative (BP-3-Cz) with a twisted electron donor–acceptor (D–A) structure is synthesized. The incorporation of heteroatoms into the twisted π-conjugated D–A backbone simultaneously endows BP-3-Cz with obvious polarity- and pressure-induced emission. Spectral analysis, X-ray diffraction, differential scanning calorimetry, and quantum chemical calculation results confirm that BP-3-Cz has special optical features related to the molecular conformation change and excited state turning to planarized intramolecular charge transfer with an increase in polarity or applied pressure. These findings contribute to the understanding of the PIE mechanism and the design of new PIE materials.

In the present study, a culture of Chaetoceros muelleri, a cosmopolitan planktonic diatom microalga present in the Sea of Cortez, was established under controlled laboratory conditions. A sulfated polysaccharide (CMSP) extraction was carried out from the biomass obtained, resulting in a yield of 2.2% (w/w of dry biomass). The CMSP sample was analyzed by Fourier transform infrared spectroscopy, showing bands ranging from 3405 to 590 cm−1 and a sulfate substitution degree of 0.10. Scanning electron microscopy with elemental analysis revealed that the CMSP particles are irregularly shaped with non-acute angles and contain sulfur. High-performance liquid chromatography coupled to a dynamic light-scattering detector yielded molecular weight (Mw), polydispersity index (PDI), intrinsic viscosity [η], and hydrodynamic radius (Rh) values of 4.13 kDa, 2.0, 4.68 mL/g, and 1.3 nm, respectively, for the CMSP. This polysaccharide did not present cytotoxicity in CCD-841 colon cells. The antioxidant activity and the glycemic index of the CMSP were 23% and 49, respectively, which gives this molecule an added value by keeping low glycemic levels and exerting antioxidant activity simultaneously.

In the title benzohydrazide derivative, C14H12N2O4, the azomethine C=N double bond has an E configuration. The hydrazide connecting bridge, (C=O)—(NH)—N=(CH), is nearly planar with C—C—N—N and C—N—N=C torsion angles of −177.33 (10) and −174.98 (12)°, respectively. The 4-hydroxyphenyl and 3,4-dihydroxyphenyl rings are slightly twisted, making a dihedral angle of 9.18 (6)°. In the crystal, molecules are connected by N—H...O and O—H...O hydrogen bonds into a three-dimensional network, while further consolidated via π–π interactions [centroid–centroid distances = 3.6480 (8) and 3.7607 (8) Å]. The conformation is compared to those of related benzylidene-4-hydroxybenzohydrazide derivatives.

In the title compound, C61H15ClN2O3, the heterocyclic ring adopts an envelope conformation, folded across the N...N line, with the 2,5-dimethoxyphenyl unit occupying a quasi-axial site. There are two N—H...O hydrogen bonds in the structure: one hydrogen bond links molecules related by a 41 screw axis to form a C(6) chain, and the other links inversion-related pairs of molecules to form an R22(8) ring. The ring motif links all of the chains into a continuous three-dimensional framework structure. Comparisons are made with the structures of some related compounds.

In each of the compounds 1-[(1,3-benzodioxol-5-yl)methyl]-4-(3-fluorobenzoyl)piperazine, C19H19FN2O3 (I), 1-[(1,3-benzodioxol-5-yl)methyl]-4-(2,6-difluorobenzoyl)piperazine, C19H18F2N2O3 (II), and 1-[(1,3-benzodioxol-5-yl)methyl]-4-(2,4-dichlorobenzoyl)piperazine, C19H19Cl2N2O3 (III), the piperazine rings adopt a chair conformation with the (1,3-benzodioxol-5-yl)methyl substituent occupying an equatorial site: the five-membered rings are all slightly folded across the O...O line leading to envelope conformations. The dihedral angle between the planar amidic fragment and the haloaryl ring is 62.97 (5)° in (I) but 77.72 (12)° and 75.50 (5)° in (II) and (III), respectively. Despite their similarity in constitution and conformation, the supramolecular interactions in (I)–(III) differ: in (I), a combination of C—H...O and C—H...π(arene) hydrogen bonds links the molecules into a three-dimensional framework structure, but there are no hydrogen bonds of any sort in either (II) or (III), although the structure of (III) contains a short Cl...Cl contact between inversion-related pairs of molecules.

Co-crystallization of racemic 1-cyclohexyl-1-phenyl-3-(piperidin-1-yl)propan-1-ol (trihexyphenidyl) with 3,5-dinitrobenzoic acid gives a simple 1:1 salt, namely 1-(3-cyclohexyl-3-hydroxy-3-phenylpropyl)piperidin-1-ium 3,5-dinitrobenzoate, C20H32NO+·C7H3N2O6−, (I), whereas a similar co-crystallization using (Z)-3-(2-chloro-9H-thioxanthen-9-yl)-N,N-dimethylpropan-1-amine (chlorprothixene) gives a 1:2 acid salt, namely (Z)-3-(2-chloro-9H-thioxanthen-9-yl)-N,N-dimethylpropan-1-aminium hydrogen bis(3,5-dinitrobenzoate), C18H19ClNS+·[H(C7H3N2O6)2]−, (II), the anion of which contains a very short O—H...O hydrogen bond, with dimensions O—H = 1.04 (3) Å, H...O = 1.41 (3) Å, O...O = 2.4197 (15) Å and O—H...O = 161 (3)°. In the cation of (I), the cyclohexyl and piperidyl rings both adopt chair conformations, whereas in the cation of (II), the central heterocyclic ring adopts a boat conformation, so that the dihedral angle between the two aryl rings is 41.56 (4)°. A combination of O—H...O, N—H...O and C—H...O hydrogen bonds links the ions of (I) into a complex chain of rings, and these chains are linked into sheets by π–π stacking interactions between inversion-related pairs of anions. In compound (II), a different combination of O—H...O, N—H...O and C—H...O hydrogen bonds links the ions into sheets. Comparisons are made with some related structures.

In 1-(2-iodobenzoyl)-4-(pyrimidin-2-yl)piperazine, C15H15IN4O, the central piperazine ring adopts an almost perfect chair conformation with the pyrimidine substituent in an equatorial site. The planar amide unit makes a dihedral angle of 80.44 (7)° with the phenyl ring. A combination of C—H...O and C—H...π(arene) hydrogen bonds links the molecules into a complex three-dimensional network structure, augmented by a π–π stacking interaction and an I...N halogen bond, all involving different pairs of inversion-related molecules. Comparisons are made with the structures of a number of related compounds.

Four 1-aryl-1H-pyrazole-3,4-dicarboxylate derivatives, one acid, two esters and a dicarbohydrazide have been synthesized starting from 3-aryl sydnones, and structurally characterized. There is an intramolecular O—H...O hydrogen bond in 1-phenyl-1H-pyrazole-3,4-dicarboxylic acid, C11H8N2O4, (I), and the molecules are linked into a three-dimensional framework structure by a combination of O—H...O, O—H...N, C—H...O and C—H...π(arene) hydrogen bonds. In each of the two esters dimethyl 1-phenyl-1H-pyrazole-3,4-dicarboxylate, C13H12N2O4, (II), and dimethyl 1-(4-methylphenyl)-1H-pyrazole-3,4-dicarboxylate, C14H14N2O4, (III), C—H...O hydrogen bonds lead to the formation of cyclic centrosymmetric dimers: in (III), one of the methoxycarbonyl groups is disordered over two sets of atomic sites having occupancies 0.71 (2) and 0.29 (2). An intramolecular N—H...O hydrogen bond is present in the structure of 1-(4-methoxyphenyl)-1H-pyrazole-3,4-dicarbohydrazide, C12H14N6O3, (IV), and the molecules are linked into a three-dimensional framework structure by a combination of N—H...O, N—H...N, N—H...π(arene) and C—H...O hydrogen bonds. Comparisons are made with the structures of a number of related compounds.

Solution-processed organic small molecule solar cells (SMSCs) have achieved efficiency over 11%. However, very few studies have focused on their stability under illumination and the origin of the degradation during the so-called burn-in period. Here, we studied the burn-in period of a solution-processed SMSC using benzodithiophene terthiophene rhodamine:[6,6]-phenyl C71 butyric acid methyl ester (BTR:PC71BM) with increasing solvent vapour annealing time applied to the active layer, controlling the crystallisation of the BTR phase. We find that the burn-in behaviour is strongly correlated to the crystallinity of BTR. To look at the possible degradation mechanisms, we studied the fresh and photo-aged blend films with grazing incidence X-ray diffraction, UV–vis absorbance, Raman spectroscopy and photoluminescence (PL) spectroscopy. Although the crystallinity of BTR affects the performance drop during the burn-in period, the degradation is found not to originate from the crystallinity changes of the BTR phase, but correlates with changes in molecular conformation – rotation of the thiophene side chains, as resolved by Raman spectroscopy which could be correlated to slight photobleaching and changes in PL spectra.

Circular RNA (circRNA) is a novel regulatory non-coding RNA and participates in diverse physiological and pathological processes. However, the structures and molecular mechanisms of circRNAs remain unclear. In this study, taking advantage of openly databases and bioinformatics analysis, we observed lots of internal complementary base-pairing sequences (ICBPS) existed in plenty of circRNAs, especially in extremely long circRNAs (el-circRNAs, > 5,000 nt). The result indicated that circRNA may not be a simple circular structure. In addition, we put forward the hypothesis of “open-close effect” in the transition for specific circRNA from normal state to morbid state. Taken together, our results not only expand the knowledge of circRNAs, but also highlight the potential molecular mechanism of circRNAs.

In the title compound, C18H18N4O6, the piperazine ring adopts a chair conformation, the amidic N atom is planar (sum of angles = 360°) and the non-amidic N atom is pyramidal (343°). There are no hydrogen bonds of any kind in the crystal, but the molecules are linked by two independent π(nitrobenzene)...π(methoxybenzene) stacking interactions to form π-stacked sheets with inter-centroid separations of 3.8444 (12) and 3.9197 (12) Å.

In organic light-emitting diodes (OLEDs), all triplet excitons can be harvested as light via reverse intersystem crossing (RISC) based on thermally activated delayed fluorescence (TADF) emitters. To realize efficient TADF, RISC should be fast. Thus, to accomplish rapid RISC, in the present study, a novel TADF emitter, namely, TpIBT-tFFO, was reported. TpIBT-tFFO was compared with IB-TRZ, which contains the same electron donor and acceptor segments, specifically iminodibenzyl and triazine moieties. TpIBT-tFFO is based on a recently proposed molecular design strategy called tilted face-to-face alignment with optimal distance (tFFO), whereas IB-TRZ is a conventional through-bond type molecule. According to quantum chemical calculations, a very large RISC rate constant, kRISC, was expected for TpIBT-tFFO because not only the lowest triplet state but also the second lowest triplet state were close to the lowest excited singlet state, as designed in the tFFO strategy. IB-TRZ has two different conformers, leading to dual emission. Conversely, owing to excellent packing, the conformation was fixed to one in the tFFO system, resulting in single-peaked emission for TpIBT-tFFO. TpIBT-tFFO displayed TADF type behavior and afforded higher photoluminescence quantum yield (PLQY) compared to IB-TRZ. The kRISC of TpIBT-tFFO was determined at 6.9 × 106 s−1, which is one of the highest values among molecules composed of only H, C, and N atoms. The external quantum efficiency of the TpIBT-tFFO-based OLED was much higher than that of the IB-TRZ-based one. The present study confirms the effectiveness of the tFFO design to realize rapid RISC. The tFFO-based emitters were found to exhibit an additional feature, enabling the control of the molecular conformations of the donor and/or acceptor segments.

The structure of the tertiary amine tris(1H-benzimidazol-2-ylmethyl)amine (C24H21N7, abbreviated ntb) has been previously reported twice as solvates, namely the monohydrate and the acetonitrile–methanol–water (1/0.5/1.5) solvate, both with the tripodal conformation formed via multiple hydrogen bonds. Now, we report the trimethanol adduct, ntb·3CH3OH, where the amine has the stair conformation featuring one benzimidazole group oriented in the opposite direction from the other two. The asymmetric unit contains one-half amine, completed through the mirror plane m in space group Pmn21 to form the ntb molecule, with the H atom for each imidazole moiety equally disordered between both N sites available in the imidazole ring. The asymmetric unit also contains one and a half methanol molecules, one being placed in general position with the hydroxy H atom disordered over two sites with occupancy ratio 1:1, while the other lies on the m mirror plane, and has thus its hydroxy H atom disordered by symmetry. As in the previously reported solvates, all imine and amine groups of the ntb molecules and the methanol molecules are involved in N—H...O and O—H...N hydrogen bonds. In the title compound, however, the involved H atom is systematically a disordered H atom provided by an imidazole group or a methanol molecule.

In the molecule of the title compound, C15H14N2O2, the 2-ethylphenyl group is disordered over two sets of atomic sites having occupancies of 0.515 (19) and 0.485 (19), and the dihedral angle between the two partial-occupancy aryl rings is 6(2)°. A combination of C—H...O hydrogen bonds and nitro...π(arene) interactions links the molecules into a continuous three-dimensional framework structure. Comparisons are made with the structures of some related compounds.

The molecule of the title compound, C13H10ClNO, (I), which contains an intramolecular O—H...N hydrogen bond, is almost planar: the dihedral angle between the two aryl rings is only 3.31 (9)°. The molecules of (I) are linked into sheets by two C—H...π(arene) hydrogen bonds and the sheets are linked into a three-dimensional structure by O—H...O hydrogen bonds. Comparisons are made with the structures of a number of related compounds.

In the molecules of both (E)-1-{3-[(5-fluoro-2-hydroxybenzylidene)amino]phenyl}ethanone, C15H12FNO2, (I), and (E)-1-{3-[(2-hydroxy-3-methoxybenzylidene)amino]phenyl}ethanone, C16H15NO3, (II), which crystallizes with Z′ = 2 in space group Pca21, there are intramolecular O—H...N hydrogen bonds, and the non-H atoms in each molecule are essentially coplanar. In the crystal of (I), molecules are linked by a single C—H...O hydrogen bond to form a C(8) chain, whereas in the crystal of (II), molecules are linked by three C—H...O hydrogen bonds to form sheets within which orthogonal C22(16) and C22(17) chains can be identified. Comparisons are made with some related structures.

Recently, the electrospun silk web has been intensively studied in terms of its biomedical applications, including tissue engineering scaffolds, due to its good biocompatibility, cytocompatibility, and biodegradability. In this study, the effect of relative humidity (RH) conditions on the morphology of electrospun silk fiber and the electrospinning production rate of silk solution was examined. In addition, the effect of RH on the molecular conformation of electrospun silk web was examined using Fourier transform infrared (FTIR) spectroscopy. As RH was increased, the maximum electrospinning rate of silk solution and fiber diameter of the resultant electrospun silk web were decreased. When RH was increased to 60%, some beads were observed, which showed that the electrospinnability of silk formic acid solution deteriorated with an increase in RH. The FTIR results showed that electrospun silk web was partially β-sheet crystallized and RH did not affect the molecular conformation of silk.

The N,N-dimethylethylamminium unit in N,N-dimethyl-[2-(2,2-diphenyl)-2-prop-2-ynyloxyacetoxy]ethylamine, C21H23NO3 (I), is disordered over two sets of atomic sites having occupancies of 0.880 (3) and 0. 120 (3), but there are no direction-specific interactions between the molecules of (I). The cation in N,N-dimethyl-[2-(2,2-diphenyl)-2-prop-2-ynyloxyacetoxy]ethylammonium 2,4,6-trinitrophenolate (picrate), C21H24NO3+·C6H2N3O7− (II), shows a similar type of disorder, with occupancies of 0.654 (11) and 0.346 (11), although the overall conformation of the cation in (II) is different from that in the neutral (I). The component ions are are linked by an almost planar three-centre N—H...(O)2 hydrogen bond, and the ion pairs are further linked by a combination of three C—H...O hydrogen bonds to form sheets. Comparisons are made with some related structures.

In both 2-amino-4,4,7,7-tetramethyl-4,5,6,7-tetrahydro-1,3- benzothiazol-3-ium benzoate, C11H19N2S+·C7H5O2−, (I), and 2-amino-4,4,7,7-tetramethyl-4,5,6,7-tetrahydro-1,3-benzothiazol-3-ium picrate (2,4,6-trinitrophenolate), C11H19N2S+·C6H2N3O7−, (II), the cations are conformationally chiral as the six-membered rings adopt half-chair conformations, which are disordered over two sets of atomic sites giving approximately enantiomeric disorder. For both cations, the bond lengths indicate delocalization of the positive charge comparable to that in an amidinium cation. The bond lengths in the picrate anion in (II) are consistent with extensive delocalization of the negative charge into the ring and onto the nitro groups, in two of which the O atoms are disordered over two sets of sites. In (I), the ionic components are linked by N—H...O hydrogen bonds to form a chain of rings, and in (II), the N—H...O hydrogen bonds link the components into centrosymmetric four-ion aggregates containing seven hydrogen bonded rings of four different types.

Bifunctional organocatalysts bearing amino and urea functional groups in a chiral molecular skeleton were applied to the enantioselective synthesis of axially chiral benzamides via aromatic electrophilic bromination. The results demonstrate the versatility of bifunctional organocatalysts for the enantioselective construction of axially chiral compounds. Moderate to good enantioselectivities were afforded with a range of benzamide substrates. Mechanistic investigations were also carried out.

A high-mineral polysaccharide (LP) was extracted from Lycium barbarum L. leaves, and the absorption of endogenous calcium, iron, and zinc was evaluated in Caco-2 cells and rat models. The absorption of these minerals ranged from 2.7 to 5.9% in Caco-2 cells, compared with 60.5–81.9% in rat models. LP had a compact globular conformation at pH ∼ 7.2 when co-cultured with Caco-2 cells, and degraded to a loosely linear structure at pH ∼ 6.7 in rat cecum. The degraded polysaccharides didn’t change the mucosal morphometry but caused higher expression of calcium transporter 1 (CAT1) and zinc transporter 1 (ZIP1) proteins in rat cecum. Furthermore, fermentation of polysaccharides in cecum also caused elevated levels of serum cytokines, including TNF-α and IL-6. GL polysaccharides could increase the bioavailability of endogenous calcium via changes in the molecular conformation and through upregulation of the expression of mineral transporter proteins.

Conformational flexibility in molecules can give rise to a range of functional group terminations at crystal surfaces and dynamic disorder in the bulk. In this work, we explore the conformational behavior of the drug molecule lovastatin in the crystallographically disordered solid and at crystal surfaces through a combination of computational modeling and spectroscopy. Gas-phase and periodic quantum-chemical calculations are used to study the potential energy surface associated with rotatable bonds to examine the disorder in bulk. These calculations are combined with vibrational and X-ray photoelectron spectroscopy measurements to obtain insight into the conformations in bulk and at the surface. Our MD simulations show that the bulk disorder is driven by cooperative motion of the butyl group on the S-butanoate moiety along one crystallographic direction beyond a unit cell. The calculations show that the O-H group can rotate relatively freely between two low-energy conformers in the gas phase but is locked in position by intermolecular H-bonding interactions in the bulk crystal, and we find tentative spectroscopic evidence for the second conformer being present at the surface. We also comment on the relative utility of these different techniques for studying molecular conformation in bulk and at surfaces and highlight possible areas for future developments.

Some studies have reported that the capacity of humic substances to improve plant growth is dependent on their ability to increase root hydraulic conductivity. It was proposed that this effect is directly related to the structural conformation in solution of these substances. To study this hypothesis, the effects on root hydraulic conductivity and growth of cucumber plants of a sedimentary humic acid and two polymers—polyacrylic acid and polyethylene glycol—presenting a molecular conformation in water solution different from that of the humic acid have been studied. The results show that whereas the humic acid caused an increase in root hydraulic conductivity and plant growth, both the polyacrylic acid and the polyethylene glycol did not modify plant growth and caused a decrease in root hydraulic conductivity. These results can be explained by the different molecular conformation in water solution of the three molecular systems. The relationships between these biological effects and the molecular conformation of the three molecular systems in water solution are discussed.

In the crystal of 2-(4-chlorophenyl)-N-(2-iodophenyl)acetamide, C14H11ClINO, molecules are linked by a combination of N—H...O and C—H...O hydrogen bonds to form a C(4)C(4)[R21(7)] chain of rings and chains of this type are linked by a combination of C—Cl...π(arene) and C—I...π(arene) interactions to form deeply puckered twofold interwoven sheets. In the crystal of 2-(4-chlorophenyl)-N-(pyrazin-2-yl)acetamide, C12H10ClN3O, molecules are linked into complex sheets by N—H...N, C—H...N and C—H...O hydrogen bonds, and by C—H...π(arene) interactions.

In the crystal of compound (I), C14H11ClOS, molecules are linked by C—H...O hydrogen bonds to form simple C(5) chains. Compound (II), C26H22O, crystallizes with Z′ = 2 in space group P-1; one of the molecules is fully ordered but the other is disordered over two sets of atomic sites having occupancies 0.644 (3) and 0.356 (3). The two disordered components differ from one another in the orientation of the isopropyl substituents, and both differ from the ordered molecules in the arrangement of the central propenone spacer unit, so that the crystal of (II) contains three distinct conformers. The ordered and disordered conformers each form a C(8) chain built from a single type of C—H...O hydrogen bond but those formed by the disordered conformers differ from that formed by the ordered form.

In the title compound, C21H17N3O3S, the non-H atoms, apart from those in the benzoyl group, are almost coplanar (r.m.s. deviation = 0.049 Å) and the benzoyl group is almost orthogonal to the plane of the rest of the molecule [dihedral angle = 80.34 (6)°]. In the crystal, a combination of N—H...O and asymmetric bifurcated O—H...(N,O) hydrogen bonds link the molecules into a three-dimensional network. Weak C—H...O interactions are also observed.