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Tetra‐cyano substituted naphthalene diimides (TCNDIs) with calculated LUMO of −5.2 eV, form one of the strongest electron‐acceptors known to date. However, the synthesis and isolation of this class of molecules remain challenging due to its reactivity emanating from its ultra‐electron‐deficiency. Herein we have established an improved synthetic methodology of TCNDIs with cost‐effective reagents and circumventing metallic catalysts. The synthesis is amenable to TCNDIs with the shortest axial alkyl groups, i. e. methyl group and also longer alkyl chains. We also gained insight on how axial alkyl chain lengths influence electron‐deficiency, Meisenheimer complex formation, reactivity, and charge‐transfer of TCNDIs from computation, spectroscopy, and electrochemical studies. The TCNDIs with Me/Et axial groups were found to be more susceptible to moist solvents vis‐à‐vis the TCNDIs with longer alkyl groups. The single crystal structures of the TCNDIs show infinitely π‐stacked structure, and a new C=O ⋅ ⋅ ⋅ C≡N or C≡N ⋅ ⋅ ⋅ π motif is discerned. Finally, toluene‐mediated charge‐transfer properties of TCNDIs in the single crystals as well as in solution have been examined. [ABSTRACT FROM AUTHOR]

The aryl diester compound, 2-methyl-1,4-phenylene bis(3,5-dibromobenzoate), C21H12Br4O4, was synthesized by esterification of methyl hydroquinone with 3,5-dibromobenzoic acid. A crystalline sample was obtained by cooling a sample of the melt (m.p. = 502 K/DSC) to room temperature. The molecular structure consists of a central benzene ring with anti-3,5-dibromobenzoate groups symmetrically attached at the 1 and 4 positions and a methyl group attached at the 2 position of the central ring. In the crystal structure (space group P1), molecules of the title aryl diester are located on inversion centers imposing disorder of the methyl group and H atom across the central benzene ring. The crystal structure is consolidated by a network of C--H...Br hydrogen bonds in addition to weaker and offset interactions involving the central benzene rings as well as the rings of the attached 3,5-dibromobenzoate groups. [ABSTRACT FROM AUTHOR]

The reaction of lithium hexa­methyl­disilyl­amide, [Li{N(Si(CH3)3)2}] (LiHMDS), with 4,4-dimethyl-2-phenyl-2-oxazoline (Phox, C11H13NO) in hexane produced colourless crystals of bis­(4,4-dimethyl-2-phenyl-2-oxazoline-κN)(hexa­methyl­disilyl­amido-κN)lithium, [Li(C6H18NSi2)(C11H13NO)2] or [Li{N(Si(CH3)3)2}(Phox)2] in high yield (89%). Despite the 1:1 proportion of the starting materials in the reaction mixture, the product formed with a 1:2 amide:oxazoline ratio. In the unit cell of the C2/c space group, the neutral mol­ecules lie on twofold rotation axes coinciding with the Li—N(amide) bonds. The lithium(I) centre adopts a trigonal–planar coordination geometry with three nitro­gen donor atoms, one from the HMDS anion and two from the oxazolines. All ligands are monodentate. In the phenyl­oxazoline units, the dihedral angle defined by the five-membered heterocyclic rings is 35.81 (5)°, while the phenyl substituents are approximately face-to-face, separated by 3.908 (5) Å. In the amide, the methyl groups assume a nearly eclipsed arrangement to minimize steric repulsion with the analogous substituents on the oxazoline rings. The non-covalent inter­actions in the solid-state structure of [Li{N(Si(CH3)3)2}(Phox)2] were assessed by Hirshfeld surface analysis and fingerprint plots. This new compound is attractive for catalysis due to its unique structural features. [ABSTRACT FROM AUTHOR]

The computation of the rotation barriers of the methyl groups (Me) of tribromomesitylene (TBM) crystals has been carried out. Experimentally, the barriers of the three Me groups of TBM are found to be high and different. These groups do not experience the same hindering environment in the crystal state. For an isolated TBM molecule, the three barriers are equal and very low. We found that a cluster of 21 TBM molecules permits the reproduction of the crystal symmetry and structure of the bulk, with a central molecule surrounded by six molecules in the same plane and seven other molecules in two planes above and below. DFT computations including dispersion corrections have been carried out using the ONIOM procedure. The Me groups of the central TBM molecule were rotated step by step to determine the conformations of lowest and highest energy for each Me, thus allowing estimation of the rotation barriers as the difference between these energies. In doing so, we found the following barrier values, namely 105, 173, and 205 cm−1, whereas the experimental values were 111, 180 and 200 cm−1. [ABSTRACT FROM AUTHOR]

Trichlorido(4-methylpiperidine)gold(III), [AuCl3(C6H13N)], 1, crystallizes in Pbca with Z = 8. Tribromido(4-methylpiperidine)gold(III), [AuBr3(C6H13N)], 2, crystallizes as two polymorphs, 2a in Pnma with Z = 4 (imposed mirror symmetry) and 2b, which is isotypic to 1. The Au--N bonds trans to Cl are somewhat shorter than those trans to Br, and the Au--Cl bonds trans to N are longer than those cis to N, whereas the Au--Br bonds trans to N are slightly shorter than the cis bonds. The methyl and AuX3 groups (X = halogen) occupy equatorial positions at the six-membered ring. The packing of all three structures involves chains of molecules with offset stacking of the AuX3 moieties associated with short Au...X contacts; for 1 and 2b these are reinforced by N--H...X hydrogen bonds, whereas for 2a there are no classical hydrogen bonds and the chains are interconnected by Br...Br contacts. [ABSTRACT FROM AUTHOR]

The asymmetric unit of the title compound, C25H18N6.H2O, comproses two molecules (I and II), together with a water molecule. The terminal phenyl groups attached to the methyl groups of the molecules I and II do not overlap completely, but are approximately perpendicular. In the crystal, the molecules are connected by N--H...N, C--H...N, O--H...N and N--H...O hydrogen bonds with each other directly and through water molecules, forming layers parallel to the (001) plane. C--H...π interactions between these layers ensure the cohesion of the crystal structure. A Hirshfeld surface analysis indicates that H...H (39.1% for molecule I; 40.0% for molecule II), C...H/H...C (26.6% for molecule I and 25.8% for molecule II) and N...H/H...N (24.3% for molecules I and II) interactions are the most important contributors to the crystal packing. [ABSTRACT FROM AUTHOR]

Reaction of Co(NCS)2 with 4-methylpyridine N-oxide in methanol leads to the formation of crystals of the title compound, [Co2(NCS)4(C6H7NO)4(CH4O)2] or Co2(NCS)4(4-methylpyridine N-oxide)4(methanol)2. The asymmetric unit consist of one CoII cation, two thiocyanate anions, two 4-methylpyridine N-oxide coligands and one methanol molecule in general positions. The H atoms of one of the methyl groups are disordered and were refined using a split model. The CoII cations octahedrally coordinate two terminal N-bonded thiocyanate anions, three 4-methylpyridine N-oxide coligands and one methanol molecule. Each two CoII cations are linked by pairs of μ-1,1(O,O)-bridging 4-methylpyridine N-oxide coligands into dinuclear units that are located on centers of inversion. Powder X-ray diffraction (PXRD) investigations prove that the title compound is contaminated with a small amount of Co(NCS)2(4-methylpyridine N-oxide)3. Thermogravimetric investigations reveal that the methanol molecules are removed in the beginning, leading to a compound with the composition Co(NCS)2(4-methylpyridine N-oxide), which has been reported in the literature and which is of poor crystallinity. [ABSTRACT FROM AUTHOR]

In the structure of the title compound, C22H22N4O4⋯C3H7NO⋯H2O, the entire tricyclic system is approximately planar except for the carbon atom bearing the two methyl groups; the methoxyphenyl ring is approximately perpendicular to the tricycle. All seven potential hydrogen-bond donors take part in classical hydrogen bonds. The main molecule and the DMF combine to form broad ribbons parallel to the a axis and roughly parallel to the ab plane; the water molecules connect the residues in the third dimension. [ABSTRACT FROM AUTHOR]

The title compound, C22H18N2O12, was obtained as a by-product during the planned synthesis of 1,2-bis(2-nitro-4,5-dimethyl phthalate)ethane by oxidative dimerization starting from dimethyl-4-methyl-5-nitro phthalate. To identify this compound unambiguously, a single-crystal structure analysis was performed. The asymmetric unit consists of half a molecule that is located at a centre of inversion. As a result of symmetry restrictions, the molecule shows an E configuration around the double bond. Both phenyl rings are coplanar, whereas the nitro and the two methyl ester groups are rotated out of the ring plane by 32.6 (1), 56.5 (2) and 49.5 (2)°, respectively. In the crystal, molecules are connected into chains extending parallel to the a axis by pairs of C--H⋯O hydrogen bonds that are connected into a tri-periodic network by additional C--H⋯O hydrogen-bonding interactions. [ABSTRACT FROM AUTHOR]

Understanding the physical properties of organic–inorganic hybrid [NH(CH3)3]2ZnCl4 is necessary for its potential application in batteries and fuel cells due to its environmentally-friendly, and highly stable character. Here, we determine its overall properties in detail, such as its orthorhombic crystal structure, and phase transition temperatures associated with five different phases. Structural geometry was studied by the chemical shifts caused by the local field around 1H. No changes were observed for the environment around 1H for CH3, whereas the 1H chemical shifts around NH in the cation were shown due to the change in the hydrogen bond N‒H···Cl. This is related to the change in Cl around Zn in the anion. In addition, the coordination geometry of 14N and 1H around 13C exhibited increased symmetry at high temperatures. Finally, we were able to understand its molecular dynamics by the significant change with temperature observed from the spin–lattice relaxation time T1ρ values, which represent the energy transfer for the 1H and 13C atoms of the cation. The activation energies obtained from the T1ρ results were 3–4 times large at phase I (> 348 K) than at phase V and IV (< 286 K). The relaxations show that the energy barriers in phases IV and V are related to the reorientation of methyl groups around the triple symmetry axis, while the reorientation of methyl groups of the cation in phase I is related to as a whole. [ABSTRACT FROM AUTHOR]

Understanding the physical properties of organic–inorganic hybrid [NH(CH3)3]2ZnCl4 is necessary for its potential application in batteries and fuel cells due to its environmentally-friendly, and highly stable character. Here, we determine its overall properties in detail, such as its orthorhombic crystal structure, and phase transition temperatures associated with five different phases. Structural geometry was studied by the chemical shifts caused by the local field around 1H. No changes were observed for the environment around 1H for CH3, whereas the 1H chemical shifts around NH in the cation were shown due to the change in the hydrogen bond N‒H···Cl. This is related to the change in Cl around Zn in the anion. In addition, the coordination geometry of 14N and 1H around 13C exhibited increased symmetry at high temperatures. Finally, we were able to understand its molecular dynamics by the significant change with temperature observed from the spin–lattice relaxation time T1ρ values, which represent the energy transfer for the 1H and 13C atoms of the cation. The activation energies obtained from the T1ρ results were 3–4 times large at phase I (> 348 K) than at phase V and IV (< 286 K). The relaxations show that the energy barriers in phases IV and V are related to the reorientation of methyl groups around the triple symmetry axis, while the reorientation of methyl groups of the cation in phase I is related to as a whole. [ABSTRACT FROM AUTHOR]

The reaction between the (R,S)-fixolide 4-methyl­thio­semicarbazone and PdII chloride yielded the title compound, [Pd(C20H30N3S)2]·C2H6O {common name: trans-bis­[(R,S)-fixolide 4-methyl­thio­semicarbazonato-κ²N²S]palladium(II) ethanol monosolvate}. The asymmetric unit of the title compound consists of one bis-thio­semicarbazonato PdII complex and one ethanol solvent mol­ecule. The thio­semicarbazononato ligands act as metal chelators with a trans configuration in a distorted square-planar geometry. A C—HS intra­molecular inter­action, with graph-set motif S(6), is observed and the coordination sphere resembles a hydrogen-bonded macrocyclic environment. Additionally, one C—HPd anagostic inter­action can be suggested. Each ligand is disordered over the aliphatic ring, which adopts a half-chair conformation, and two methyl groups [s.o.f. = 0.624 (2):0.376 (2)]. The disorder includes the chiral carbon atoms and, remarkably, one ligand has the (R)-isomer with the highest s.o.f. value atoms, while the other one shows the opposite, the atoms with the highest s.o.f. value are associated with the (S)-isomer. The N—N—C(=S)—N fragments of the ligands are approximately planar, with the maximum deviations from the mean plane through the selected atoms being 0.0567 (1) and −0.0307 (8) Å (r.m.s.d. = 0.0403 and 0.0269 Å) and the dihedral angle with the respective aromatic rings amount to 46.68 (5) and 50.66 (4)°. In the crystal, the complexes are linked via pairs of N—HS inter­actions, with graph-set motif R2²(8), into centrosymmetric dimers. The dimers are further connected by centrosymmetric pairs of ethanol mol­ecules, building mono-periodic hydrogen-bonded ribbons along [011]. The Hirshfeld surface analysis indicates that the major contributions for the crystal cohesion are [atoms with highest/lowest s.o.f.s considered separately]: HH (81.6/82.0%), HC/CH (6.5/6.4%), HN/NH (5.2/5.0%) and HS/SH (5.0/4.9%). [ABSTRACT FROM AUTHOR]

Herein, a 2‐fold interpenetrated metal‐organic framework (MOF) Zn‐BPZ‐TATB with accessible N/O active sites in nonpolar pore surfaces was reported for one‐step C2H4 purification from C2H6 or C3H6 mixtures as well as recovery of C3H6 from C2H6/C3H6/C2H4 mixtures. The MOF exhibits the favorable C2H6 and C3H6 uptakes (>100 cm3 g−1 at 298 K under 100 kPa) as well as selective adsorption of C2H6 and C3H6 over C2H4. The C3H6‐ and C2H6‐selective feature were investigated detailedly by experimental tests as well as sorption kinetic studyies. Molecular modelling revealed the multiple interactions between C3H6 or C2H6 molecules and methyl groups as well as triazine rings in pores. Zn‐BPZ‐TATB not only can directly generate 323.4 L kg−1 and 15.4 L kg−1 of high‐purity (≥99.9 %) C2H4 from C3H6/C2H4 and C2H6/C2H4 mixtures, but also provide a large high‐purity (≥99.5 %) C3H6 recovery capacity of 60.1 L kg−1 from C3H6/C2H4 mixtures. More importantly, the high‐purity C3H6 (≥99.5 %) and C2H4 (≥99.9 %) with the productivities of 38.2 and 12.7 L kg−1 can be simultaneously obtained from C2H6/C3H6/C2H4 mixtures through a single adsorption/desorption cycle. [ABSTRACT FROM AUTHOR]

Herein, a 2‐fold interpenetrated metal‐organic framework (MOF) Zn‐BPZ‐TATB with accessible N/O active sites in nonpolar pore surfaces was reported for one‐step C2H4 purification from C2H6 or C3H6 mixtures as well as recovery of C3H6 from C2H6/C3H6/C2H4 mixtures. The MOF exhibits the favorable C2H6 and C3H6 uptakes (>100 cm3 g−1 at 298 K under 100 kPa) as well as selective adsorption of C2H6 and C3H6 over C2H4. The C3H6‐ and C2H6‐selective feature were investigated detailedly by experimental tests as well as sorption kinetic studyies. Molecular modelling revealed the multiple interactions between C3H6 or C2H6 molecules and methyl groups as well as triazine rings in pores. Zn‐BPZ‐TATB not only can directly generate 323.4 L kg−1 and 15.4 L kg−1 of high‐purity (≥99.9 %) C2H4 from C3H6/C2H4 and C2H6/C2H4 mixtures, but also provide a large high‐purity (≥99.5 %) C3H6 recovery capacity of 60.1 L kg−1 from C3H6/C2H4 mixtures. More importantly, the high‐purity C3H6 (≥99.5 %) and C2H4 (≥99.9 %) with the productivities of 38.2 and 12.7 L kg−1 can be simultaneously obtained from C2H6/C3H6/C2H4 mixtures through a single adsorption/desorption cycle. [ABSTRACT FROM AUTHOR]

Herein, a 2‐fold interpenetrated metal‐organic framework (MOF) Zn‐BPZ‐TATB with accessible N/O active sites in nonpolar pore surfaces was reported for one‐step C2H4 purification from C2H6 or C3H6 mixtures as well as recovery of C3H6 from C2H6/C3H6/C2H4 mixtures. The MOF exhibits the favorable C2H6 and C3H6 uptakes (>100 cm3 g−1 at 298 K under 100 kPa) as well as selective adsorption of C2H6 and C3H6 over C2H4. The C3H6‐ and C2H6‐selective feature were investigated detailedly by experimental tests as well as sorption kinetic studyies. Molecular modelling revealed the multiple interactions between C3H6 or C2H6 molecules and methyl groups as well as triazine rings in pores. Zn‐BPZ‐TATB not only can directly generate 323.4 L kg−1 and 15.4 L kg−1 of high‐purity (≥99.9 %) C2H4 from C3H6/C2H4 and C2H6/C2H4 mixtures, but also provide a large high‐purity (≥99.5 %) C3H6 recovery capacity of 60.1 L kg−1 from C3H6/C2H4 mixtures. More importantly, the high‐purity C3H6 (≥99.5 %) and C2H4 (≥99.9 %) with the productivities of 38.2 and 12.7 L kg−1 can be simultaneously obtained from C2H6/C3H6/C2H4 mixtures through a single adsorption/desorption cycle. [ABSTRACT FROM AUTHOR]

Herein, a 2‐fold interpenetrated metal‐organic framework (MOF) Zn‐BPZ‐TATB with accessible N/O active sites in nonpolar pore surfaces was reported for one‐step C2H4 purification from C2H6 or C3H6 mixtures as well as recovery of C3H6 from C2H6/C3H6/C2H4 mixtures. The MOF exhibits the favorable C2H6 and C3H6 uptakes (>100 cm3 g−1 at 298 K under 100 kPa) as well as selective adsorption of C2H6 and C3H6 over C2H4. The C3H6‐ and C2H6‐selective feature were investigated detailedly by experimental tests as well as sorption kinetic studyies. Molecular modelling revealed the multiple interactions between C3H6 or C2H6 molecules and methyl groups as well as triazine rings in pores. Zn‐BPZ‐TATB not only can directly generate 323.4 L kg−1 and 15.4 L kg−1 of high‐purity (≥99.9 %) C2H4 from C3H6/C2H4 and C2H6/C2H4 mixtures, but also provide a large high‐purity (≥99.5 %) C3H6 recovery capacity of 60.1 L kg−1 from C3H6/C2H4 mixtures. More importantly, the high‐purity C3H6 (≥99.5 %) and C2H4 (≥99.9 %) with the productivities of 38.2 and 12.7 L kg−1 can be simultaneously obtained from C2H6/C3H6/C2H4 mixtures through a single adsorption/desorption cycle. [ABSTRACT FROM AUTHOR]

The crystal structure and a Hirshfeld surface analysis of the substituted anilinium salt 4-(dimethylazaniumyl)-2-hydroxyanilinium dichloride monohydrate, C8H14N2O+·2Cl- ·H2O, at low temperature (90 K) are presented. The organic cation is essentially planar: the r.m.s. deviation of its non-hydrogen atoms (aside from the two methyl groups) is 0.0045 A °. The methyl carbons are 1.3125 (12) A ° and 1.1278 (12) A ° either side of the mean plane. The crystal packing involves extensive hydrogen bonding of types O--H...Cl, N--H...Cl, N--H...OW, and OW--HW...Cl (where W = water), which arrange into chains of R2 4(12) motifs that combine to form corrugated layers parallel to (101). Atom-atom contacts for the cation primarily involve hydrogen, leading to the most abundant coverage percentages being 51.3% (H...H), 23.0% (H...Cl), 12.9% (H....O), and 9.7% (C...H). [ABSTRACT FROM AUTHOR]

Luminescent N-heterocyclic carbene chloride copper (I) complexes incorporating pyrene chromophore (1-Pyrenyl-NHC-R)-Cu-Cl, (3, 4) have been prepared and fully characterized. Two complexes were prepared with R = methyl (3) and R = naphthyl groups (4) at the nitrogen center of the carbene unit to tune their electronic properties. The molecular structures of 3 and 4 have been elucidated by X-ray diffraction and confirm the formation of the target compounds. Preliminary results reveal that all compounds including the imidazole-pyrenyl ligand 1 are emissive in the blue region at room temperature in solution and in solid-state. All complexes display quantum yields comparable or higher when compared to the parent pyrene molecule. Interestingly replacement of the methyl by naphthyl group increases the quantum yield by almost two-folds. These compounds might show promise for applications as optical displays. [ABSTRACT FROM AUTHOR]

The reaction of [{Ir(µ-Cl)(coe)2}2] (1, coe = cis-cyclooctene) with the bulky tertiary phosphane P(o-tolyl)3 in dichloromethane at room temperature was investigated. It afforded in good yield the tri-coordinate iridium(I) complex [IrCl{P(o-tolyl)3}2] (2) which was characterized in the solid state by a single-crystal X-ray diffraction study revealing a molecular structure of a rare tri-coordinate complex. The iridium(I) complex is stabilized by an agostic interaction of a hydrogen atom from the methyl group of the bulky phosphane ligand to fill the fourth unsaturated coordination site. The title compound crystallized from dichloromethane/diethyl ether as orange crystals in a mixture of two modifications (monoclinic P21/c, 2a, and orthorhombic Pbca, 2b). The co-existence of the two components as a nearly 1:1 mixture in the crystalline bulk material was supported by solid-state 31P{1H} NMR measurements. [ABSTRACT FROM AUTHOR]

The 22nd genetically encoded amino acid, pyrrolysine, plays a unique role in the key step in the growth of methanogens on mono-, di-, and tri-methylamines by activating the methyl group of these substrates for transfer to a corrinoid cofactor. Previous crystal structures of the Methanosarcina barkeri monomethylamine methyltransferase elucidated the structure of pyrrolysine and provide insight into its role in monomethylamine activation. Herein, we report the second structure of a pyrrolysine-containing protein, the M. barkeri trimethylamine methyltransferase MttB, and its structure bound to sulfite, a substrate analog of trimethylamine. We also report the structure of MttB in complex with its cognate corrinoid protein MttC, which specifically receives the methyl group from the pyrrolysine-activated trimethylamine substrate during methanogenesis. Together these structures provide key insights into the role of pyrrolysine in methyl group transfer from trimethylamine to the corrinoid cofactor in MttC. Structures of Methanosarcina barkeri trimethylamine methyltransferase (MttB) with its substrates reveal the role of pyrrolysine in methyl group transfer from trimethylamine to the corrinoid cofactor in MttC. [ABSTRACT FROM AUTHOR]

Ladderane lipids (found in the membranes of anaerobic ammonium-oxidizing [anammox] bacteria) have unique ladder-like hydrophobic groups, and their highly strained exotic structure has attracted the attention of scientists. Although enzymes encoded in type II fatty acid biosynthesis (FASII) gene clusters in anammox bacteria, such as S-adenosyl-l-methionine (SAM)-dependent enzymes, have been proposed to construct a ladder-like structure using a substrate connected to acyl carrier protein from anammox bacteria (AmxACP), no experimental evidence to support this hypothesis was reported to date. Here, we report the crystal structure of a SAM-dependent methyltransferase from anammox bacteria (AmxMT1) that has a substrate and active site pocket between a class I SAM methyltransferase-like core domain and an additional α-helix inserted into the core domain. Structural comparisons with homologous SAM-dependent C-methyltransferases in polyketide synthase, AmxACP pull-down assays, AmxACP/AmxMT1 complex structure predictions by AlphaFold, and a substrate docking simulation suggested that a small compound connected to AmxACP could be inserted into the pocket of AmxMT1, and then the enzyme transfers a methyl group from SAM to the substrate to produce branched lipids. Although the enzymes responsible for constructing the ladder-like structure remain unknown, our study, for the first time, supports the hypothesis that biosynthetic intermediates connected to AmxACP are processed by SAM-dependent enzymes, which are not typically involved in the FASII system, to produce the ladder-like structure of ladderane lipids in anammox bacteria. [ABSTRACT FROM AUTHOR]

The structure of the salt-type methylene blue citrate hydrate, [MB]+[H3Cit]– × 0.18H2O (where [MB]+ represents the methylene blue cation and [H3Cit]– the anion of the mono-deprotonated citric acid), has been determined by single-crystal X-ray diffraction. The [MB]+ cation is planar and stacked in an antiparallel fashion, exhibiting π–π stacking associations at an interplane distance of 3.746(6) Å. The [MB]+ cation forms short contacts of the C–H⋯O type with the citrate anion through methyl groups of the NMe2 substituents. Water molecules are distributed in the voids between stacks of the [MB]+ cations with very low site occupancies (total 0.18) and do not form hydrogen bonds with the citrate anion, but feature hydrogen bonds between the water molecules. In order to visualize the intermolecular interactions in the crystal structure of the title compound, a Hirshfeld surface analysis was carried out. [ABSTRACT FROM AUTHOR]

This article reports a practical synthesis of tert-butyl acetylcarbamate, C7H13- NO3, from N-Boc-thioacetamide and the study of its crystal structure. The reaction proceeds in the presence of natural phosphate as a catalyst, with excellent yield, simple workup and benign environment. The crystal structure was refined using a transferred multipolar atom model. In the crystal, symmetrical pairs of strong N--H-- ...O hydrogen bonds connect the molecules into dimers with an R2(8) ring motif. The interactions between neighbouring dimers are mostly van der Waals, between hydrophobic methyl groups. Hirshfeld surface analysis shows the major contributions to the crystal packing are from H--H (42.6%) and O--H (26.7%) contacts. [ABSTRACT FROM AUTHOR]

Oligourea foldamers fold into 2.5‐helices. Most of the known modifications of the backbone, such as NH or CO group substitutions or incorporations of non‐canonical residues, do not change the conformational properties of the resulting oligourea oligomers. In this study, we examined the structural influence of the methyl group, substituting NH protons in one or two residues at the N‐terminus of the foldamer. Such N‐methylated oligoureas appear to be helically folded with helix parameters determined from the crystal structure being almost the same as for non‐methylated oligomers. Solution studies (CD, NMR) reveal that the backbone with N‐Me urea groups is more flexible, but the urea group is still predominantly in trans,trans conformation. N‐Methylation does not change the structural properties of oligourea foldamers, and thus may be a useful modification for modulating the strength of hydrogen bonds and intermolecular interactions. [ABSTRACT FROM AUTHOR]

The title mol­ecule, C21H26N2O3, adopts a V-shaped conformation and is chiral at the C atom with methyl group attached at the common cut of the edges of the V-conformation and crystallizes as a racemate. It also contains an intra­molecular O--H⋯N hydrogen bond. In the crystal, N--H⋯O hydrogen bonds form chains of mol­ecules extending along the c-axis direction, together with normal van der Waals contacts. The roles of the various inter­molecular inter­actions were clarified by Hirshfeld surface analysis, which reveals that the most important contributions to the crystal packing are from H⋯H (62.6%), C⋯H/H⋯C (15.8%) and O⋯H/H⋯O (15.3%) contacts. [ABSTRACT FROM AUTHOR]

In the fused ring system of the title mol­ecule, C31H35NO4, the conformation of the central di­hydro­pyridine ring is inter­mediate between boat and envelope with the N and the opposite C atoms lying out of the basal plane. The conformations of terminal rings are close to envelope, with the atoms substituted by two methyl groups as the flaps. In the crystal, the mol­ecules are linked by O--H⋯O hydrogen bonds into helical chains. The Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H⋯H (63.2%), O⋯H/H⋯O (20.1%) and C⋯H/H⋯C (14.4%) contacts. Quantum chemical calculations of the frontier mol­ecular orbitals were carried out to characterize the chemical reactivity of the title compound. [ABSTRACT FROM AUTHOR]

The redetermined structure of 2-(2-hydroxyphenyl)-1,3-bis(4-methoxybenzyl)-1,3-diazinan-5-ol, C26H30N2O4, at 173 K has orthorhombic (Pbca) symmetry. It was previously described by Bolte et al. [ Private Communication (refcode EWICEV). CCDC, Cambridge, England]. The title compound resulted from the condensation reaction between 1,3-bis{[(4-methoxyphenyl)methyl]amino}-propan-2-ol and 2-hydroxybenzaldehyde in CH3OH. The structure exhibits disorder. One of the 4-methoxybenzyl groups, the hydroxy group bonded to the 1,3-diazinan ring, and the methyl group of the methoxy residue are disordered over two orientations, with occupancies of 0.807 (3)/0.193 (3), 0.642 (5)/ 0.358 (5), and 0.82 (4)/0.18 (4), respectively. The dihedral angles between the mean planes of the central 1,3-diazinan-5-ol and the 4-methoxyphenyl rings (both occupancy components of the disordered ring) are 88.65 (13), 85.79 (14) and 83.4 (7)°. The crystal packing is sustained by C--H⋯O and O--H⋯π interactions, giving rise to infinite chains running along the b-axis direction. [ABSTRACT FROM AUTHOR]

As a follow-up to our research on the chemistry of disubstituted ferrocene derivatives, the synthesis and the structure of the title compound, [Fe(C5H5)(C15H19N)]I⋅CH2Cl2, is described. The cation molecule is built up from a ferrocene disubstituted by a trimethylammonium methyl group and a phenyl ring. The asymmetric unit contains the iodide to equilibrate the charge and a disordered dichloromethane solvate. The disordered model results from a roughly statistical exchange (0.6/0.4) between one Cl and one H. The packing of the structure is stabilized by weak C--H⋯X (X = I, Cl), C--H⋯π(Cp) and C--Cl ⋯π(phenyl) interactions, building a three-dimensional network. The cation has planar chirality with Sp(Fc) absolute configuration. The structure of the title compound is compared with related disubstituted (trimethylammonio)methyl ferrocenes. [ABSTRACT FROM AUTHOR]

In the title compound, C22H20N2O2, both six-membered rings of the fused heterocyclic system display envelope conformations; the two carbon atoms bearing the methyl groups and the naphthyl substituent both lie outside the planes of the other atoms of each ring. In the crystal, the amino group forms hydrogen bonds of the types N--H...O C and N--H...N C, leading to the formation of a double layer structure propagating parallel to the bc plane. Weak C--H...O and C--H... interactions may reinforce the layers. [ABSTRACT FROM AUTHOR]

The extraction properties of 2,3-bis(diphenylphosphinyl)buta-1,3-diene (L1) and 3,4-bis(diphenylphosphinyl)-2,5-dimethylhexa-2,4-diene (L2) with respect to f elements are studied for the extraction of microquantities of U(VI) and Th(IV) from HNO3 solutions with solutions of the extracting agents in 1,2-dichloroethane. The introduction of methyl groups into the 1,3-butadiene carbon skeleton of bis(phosphine oxide) increases the efficiency of U(VI) extraction. The coordination properties of bis(phosphine oxides) L1 and L2 are studied for the complexes with uranyl nitrate. The crystal structures of bis(phosphine oxide) L1·THF (CIF file CCDC no. 2107403) and its complexes with uranyl nitrate I and II (CIF files CCDC nos. 2107404 and 2107405, respectively) are confirmed by X-ray diffraction data. [ABSTRACT FROM AUTHOR]

The reaction of three equivalents of 2-(trifluoroacetyl)pyrrole with triols [RC(CH2OH)3, R=H, CH3, CH2OH] produce triesters of pyrrole-2-carboxylic acid (1–3, respectively) which crystallize in space groups with molecular C3 symmetry coinciding with the crystallographic symmetry (averaged in the case of R=CH2OH). All are unsolvated. Compound 1 crystallizes in space group P-3 and 2 and 3 in space group P-43n. In all three, molecules form three R22(10) Hydrogen-bonded interactions between syn pyrrole N-H and carboxyl C = O on neighboring molecules. In 1, molecules are linked into infinite chains and hexamolecular rings, and the cavity at the center of the rings (site symmetry − 3) is too small to harbor a guest molecule. In 2 and 3, supramolecular assemblies radiate from four molecules with methyl and hydroxymethyl groups at tetrahedral sites in the cubic structures. Computations confirm the importance of Hydrogen-bonding in these assemblies which add to the hundreds of similar pyrrole carboxylates previously described. Applications of the R22(10) hydrogen bond motif formed between two pyrrole-2-carboxylate moieties in the design of hydrogen bonded framework. Three tripodal pyrrole-2-carboxylate compounds were synthesized, and their structure were characterized by X-ray crystallography. The three compounds self-assembled into hexamer or cubic supramolecular structures. The relibility of the motif was also proved by DFT calculations and search in Cambridge Structural Database (CSD). [ABSTRACT FROM AUTHOR]

Caffeic acid O -methyltransferase from Ligusticum chuanxiong (LcCOMT) showed strict regiospecificity despite a relative degree of preference. Compared with caffeic acid, methyl caffeate was the preferential substrate by its low Km and high Kcat. In this study, we obtained the SAM binary (1.80 Å) and SAH binary (1.95 Å) complex LcCOMT crystal structures, and established the ternary complex structure with methyl caffeate by molecular docking. The active site of LcCOMT included phenolic substrate pocket, SAM/SAH ligand pocket and conserved catalytic residues as well. The regiospecificity of LcCOMT that permitted only 3-hydroxyl group to be methylated arise from the interactions between the active site and the phenyl ring. However, the propanoid tail governed the relative preference of LcCOMT. The ester group in methyl caffeate stabilized the anionic intermediate caused by His268-Asp269 pair, whereas caffeic acid was unable to stabilize the anionic intermediate due to the adjacent carboxylate anion in the propanoid tail. Ser183 residue formed an additional hydrogen bond with SAH and its role was identified by S183A mutation. Ile318 residue might be a potential site for determination of substrate preference, and its mutation led to the change of tertiary conformation. The results supported the selective mechanism of LcCOMT. [ABSTRACT FROM AUTHOR]

Poly(p-phenylene alkylene)s were synthesized by Kumada coupling reaction of α,ω-dibromoalkane (BR) (1,6-dibromohexane (BH), 1,8-dibromooctane (BO), 1,10-dibromodecane (BD), 1,12-dibromododecane (BDD)), and p-dichlorobenzene (CB). The corresponding poly(p-phenylene alkylene)s (PPPRs) with low molecular weight were obtained in moderate yields. Polymer chain ends of methyl group was detected in 13CNMR spectroscopy, indicating preferential termination of BR. Wide angle X-ray diffraction (WAXD) profile of the poly(p-phenylene hexylene) (PPPH) showed a diffraction peak at 2θ = 20.4°. Poly(p-phenylene octylene) (PPPO), poly(p-phenylene decylene) PPPD, and poly(p-phenylene dodecylene) PPPDD showed the different WAXD profiles from that of PPPH, and the diffraction peaks at around 2θ = 18° and 24° were detected in their WAXD profiles. PPPD and PPPDD also showed a diffraction peak at 2θ = 21.6°, which was not detected in the WAXD profile of PPPO. FT-IR spectra in the frequency region, 710–740 cm−1, of methylene rocking vibration of the PPPRs indicated hexagonal crystal in PPPH and triclinic-based crystal in PPPO, PPPD, and PPPDD. All the PPPRs showed melting point, which decreased with increasing of methylene length of the BR used as following, PPPH: 131.2 °C, PPPO: 91.1 °C, PPPD: 84.6 °C, PPPDD: 80.1 °C,. Poly(p-phenylene co-alkylenes)s (PPPCRs) were newly prepared by polymerizations of two kinds of BRs, BH/BO, BH/BD, or BO/BD, with CB. The PPPCRs showed the lower melting temperatures than those of the corresponding PPPRs. The WAXD profiles of the PPPCRs showed the diffraction peaks derived from both the corresponding PPPRs, and their intensities were depended on the feed ratios of the BRs. [ABSTRACT FROM AUTHOR]

In the title compound, C16H14N2O2, the 2,3-di­hydro-1-benzo­furan ring system is essentially planar and makes a dihedral angle of 3.69 (7)° with the di­methyl­phenyl ring. The mol­ecular conformation is stabilized by an intra­molecular N—H···O hydrogen bond with an S(6) ring motif. In the crystal, mol­ecules are connected by C—H···π and π–π stacking inter­actions, forming a layer lying parallel to the (11...) plane. One methyl group is disordered over two orientations, with occupancies of 0.67 (4) and 0.33 (4). Hirshfeld surface analysis indicates that the most important contributions to the crystal packing are from H···H (51.2%), O···H/H···O (17.9%), C···H/H···C (15.2%) and C···C (8.1%) contacts. [ABSTRACT FROM AUTHOR]

Large scale synthesis of cycloparaphenyleneacetylenes has been challenging due to low macrocyclization yields and harsh aromatization methods that often decompose strained alkynes. Herein, a cis-stilbene-based building block is subjected to alkyne metathesis macrocylization. The following sequence of alkene-selective bromination and dehydrobromination afforded a [8]cycloparaphenyleneacetylene derivative in high yield with good scalability. X-Ray crystal structure and computational analysis revealed a unique same-rim conformation for the eight methyl groups on the nanohoop. [ABSTRACT FROM AUTHOR]

Two new 1-(thiazol-2-yl)-4,5-dihydropyrazoles have been synthesized from simple precursors, and characterized both spectroscopically and structurally. In addition, two intermediates in the reaction pathway have been isolated and characterized, one of them structurally. The molecules of the intermediate (E)- 1-(4-methoxyphenyl)-3-[4-(prop-2-ynyloxy)phenyl]prop-2-en-1-one, C19H16O3 (I), are linked by a combination of C—HO and C—H(arene) hydrogen bonds to form ribbons. The products (RS)-5-(4-methoxyphenyl)-1-(4- phenythiazol-2-yl)-3-[4-(prop-2-ynyloxy)phenyl]-4,5-dihydro-1H-pyrazole, C28H23N3O2S (II), and (RS)-5-(4-methoxyphenyl)-1-[4-(4-methylphenyl)thiazol-2- yl]-3-[4-(prop-2-ynyloxy)phenyl]-4,5-dihydro-1H-pyrazole, C29H25N3O2S (III), are closely related – differing only by presence or absence of a methyl group at the arylthiazolyl substituent – and crystallize in an isomorphous setting. Both molecules contain an effectively planar dihydro-pyrazole ring, and possess an overall T-shaped structure, which is a characteristic of triaryl-substituted 4,5-dihydro-1-(thiazol-2-yl)pyrazole compounds. The crystal packing is characterized by intermolecular C—HS and C—H (aryl/alkyne) interactions. A combination of two C—H(arene) hydrogen bonds links the product molecules into sheets. [ABSTRACT FROM AUTHOR]

Two crystallographically independent molecules are present in the asymmetric unit of the title compound, C14H11NO2, with virtually identical geometries. The carbazole units are planar. The hydroxy group at position 1, carbaldehyde group at position 2, and methyl group at position 8 (with the exception of two H atoms) are coplanar with the attached benzene rings. The dihedral angle between the two benzene rings is 2.20(9)° in molecule A and 2.01(9)° in molecule B. The pyrrole ring makes dihedral angles of 0.82(10) and 1.40(10)° [0.84(10) and 1.18(10)° in molecule B] with the (-CH3)-substituted and (-OH and -CHO) substituted benzene rings, respectively. The molecular structure is stabilized by the intramolecular O--H···O hydrogen bonds, while the crystal structure features N--H···O and C--H···O hydrogen bonds. A range of π-π contacts further stabilizes the crystal structure. [ABSTRACT FROM AUTHOR]

Maytansinoids, the chemical derivatives of Maytansine, are commonly used as potent cytotoxic payloads in antibody-drug conjugates (ADC). Structure-activity-relationship studies had identified the C3 ester side chain as a critical element for antitumor activity of maytansinoids. The maytansinoids bearing the methyl group at C3 position with D configuration were about 100 to 400-fold less cytotoxic than their corresponding L-epimers toward various cell lines. The detailed mechanism of how chirality affects the anticancer activity remains elusive. In this study, we determined the high-resolution crystal structure of tubulin in complex with maytansinol, L-DM1-SMe and D-DM1-SMe. And we found the carbonyl oxygen atom of the ester moiety and the tail thiomethyl group at C3 side chain of L-DM1-SMe form strong intramolecular interaction with the hydroxyl at position 9 and the benzene ring, respectively, fixing the bioactive conformation and enhancing the binding affinity. Additionally, ligand-based and structure-based virtually screening methods were used to screen the commercially macrocyclic compounds library, and 15 macrocyclic structures were picketed out as putatively new maytansine-site inhibitors. Our study provides a possible strategy for the rational discovery of next-generation maytansine site inhibitors. • We determined the crystal structures of tubulin in complex with Maytansinol, L-DM1-SMe and D-DM1-SMe. • The crystal structures explain how the chirality of the methyl group at C3 position affects the anticancer activity. • A pharmaphore model was built by analyzing the critical residues and pharmaphore features of Maytansine-site ligands. • 15 macrocyclic structures were picked out as putatively new Maytansine-site inhibitors through the virtual screening methods. [ABSTRACT FROM AUTHOR]

Human methyltransferase-like (METTL) proteins transfer methyl groups to nucleic acids, proteins, lipids, and other small molecules, subsequently playing important roles in various cellular processes. In this study, we performed integrated genomic, transcriptomic, proteomic, and clinicopathological analyses of 34 METTLs in a large cohort of primary tumor and cell line data. We identified a subset of METTL genes, notably METTL1, METTL7B, and NTMT1, with high frequencies of genomic amplification and/or up-regulation at both the mRNA and protein levels in a spectrum of human cancers. Higher METTL1 expression was associated with high-grade tumors and poor disease prognosis. Loss-of-function analysis in tumor cell lines indicated the biological importance of METTL1, an m7G methyltransferase, in cancer cell growth and survival. Furthermore, functional annotation and pathway analysis of METTL1-associated proteins revealed that, in addition to the METTL1 cofactor WDR4, RNA regulators and DNA packaging complexes may be functionally interconnected with METTL1 in human cancer. Finally, we generated a crystal structure model of the METTL1–WDR4 heterodimeric complex that might aid in understanding the key functional residues. Our results provide new information for further functional study of some METTL alterations in human cancer and might lead to the development of small inhibitors that target cancer-promoting METTLs. [ABSTRACT FROM AUTHOR]

Transverse nuclear spin relaxation is a sensitive probe of chemical exchange on timescales on the order of microseconds to milliseconds. Here we present an experiment for the simultaneous measurement of the relaxation rates of two quadruple-quantum transitions in 13CH3-labelled methyl groups. These coherences are protected against relaxation by intra-methyl dipolar interactions and so have unexpectedly long lifetimes within perdeuterated biomacromolecules. However, these coherences also have an order of magnitude higher sensitivity to chemical exchange broadening than lower order coherences and therefore provide ideal probes of dynamic processes. We show that analysis of the static magnetic field dependence of zero-, double- and quadruple-quantum Hahn echo relaxation rates provides a robust indication of chemical exchange and can determine the signed relative magnitudes of proton and carbon chemical shift differences between ground and excited states. We also demonstrate that this analysis can be combined with established Carr-Purcell-Meiboom-Gill (CPMG) relaxation dispersion measurements, providing improved precision in parameter estimates, particularly in the determination of ¹H chemical shift differences. [ABSTRACT FROM AUTHOR]

The gas phase structures and internal dynamics of N,N-diethylacetamide were determined with very high accuracy using a combination of molecular beam Fourier-transform microwave spectroscopy and quantum chemical calculations at high levels. Conformational studies yielded five stable con-formers with C1 symmetry. The two most energetically favorable conformers, conformer I and II, could be found in the experimental spectrum. For both conformers, quadrupole hyperfine splittings of the 14N nucleus and torsional fine splittings due to the internal rotation of the acetyl methyl group occurred in the same order of magnitude and were fully assigned. The rotational constants, cen-trifugal distortion constants as well as the quadrupole coupling constants of the 14N nucleus were determined and fitted to experimental accuracy. The V3 potentials were found to be 517.04(13) cm-1 and 619.48(91) cm-1 for conformer I and II, respectively, and compared to the V3 potentials found in other acetamides. Highly accurate CCSD(T) and DMC calculations were carried out for calcu-lating the barriers to internal rotation in comparison with the experimentally deduced V3 values. [ABSTRACT FROM AUTHOR]

One new uranyl tetracarboxylate, [UO2(H2L3)(H2O)]·3H2O, was synthesized hydrothermally from a methyl group decorated semi-rigid tetracarboxylic acid ligand and systematically characterized using powder and single-crystal X-ray diffraction, IR, EA, TGA, and luminescent methods. The four carboxylate groups in the carboxylic ligand were all monodentate bridging and the uranyl cations are linked by tetracarboxylic ligands to form a two-dimensional layered crystal structure. Introduction of methyl groups has a large effect on the speciation of uranyl carboxylates. The thermal behavior and luminescent properties are also investigated. [ABSTRACT FROM AUTHOR]

In the title molecular salt, (C6H16N2)[CoCl4], the complete dication is generated by crystallographic inversion symmetry and the piperazine ring adopts a chair conformation with the pendant methyl groups in equatorial orientations. The complete dianion is generated by crystallographic twofold symmetry. In the crystal, the (C6H16N2)2+ and [CoCl4]2- ions are linked by N--H⋯Cl and C--H⋯Cl hydrogen bonds, thereby forming a two-dimensional supramolecular network. The Hirshfeld surface analysis and fingerprint plots reveal that the largest contributions to the crystal stability come from H⋯Cl/Cl⋯H (68.4%) and H⋯H (27.4%) contacts. [ABSTRACT FROM AUTHOR]

A moisture stable microporous metal–organic framework (MOF) decorated with methyl-rich groups was designed and synthesized for efficiently capturing and separating CO 2. The MOF shows simultaneously high CO 2 uptake as well as ultrahigh CO 2 /N 2 , CO 2 /CO and CO 2 /CH 4 selectivity, affording high purity CO 2 , N 2 , CO and CH 4 gases through one-step breakthrough/desorption experiments. [Display omitted] • The MOF with nonpolar methyl groups in pores exhibits good moisture stability. • The MOF displays high uptake and selectivity for CO 2 over N 2 , CH 4 and CO. • High-purity CO 2 and N 2 /CO/CH 4 were simultaneously obtained in one breakthrough. • The accessible methyl groups in pores form multiple C-H···O interactions for CO 2. Utilizing porous adsorbents to capture CO 2 from flue gas or removal of CO 2 impurity from other high-value chemicals is an effective way for alleviating the greenhouse effect, but selective and reversible capture of CO 2 is still a challenge. In this study, we report a moisture stable metal–organic framework (Zn-dmtrz-mip) that combines high CO 2 uptake with a low affinity for other gases for highly efficient CO 2 capture and separation performance. Zn-dmtrz-mip displays a high CO 2 uptake of 65.4 cm3 g−1 as well as ultrahigh CO 2 /N 2 (11974 and 681 for 50/50 and 15/85 mixtures, respectively), CO 2 /CO (110.0 and 50.8 for 50/50 and 10/90 mixtures, respectively), which superior to many reported MOFs. Breakthrough experiments visualized that Zn-dmtrz-mip is not only capable of directly obtaining high-purity (99.9 %) N 2 , CH 4 and CO, but also achieving high-purity (99.5 %) CO 2 recovery. The stability experiments showed that Zn-dmtrz-mip maintained its structure and CO 2 adsorption uptake after exposure in air and moisture environments (RH = 65 %) as well as in acidic (pH = 3) and basic (pH = 11) solutions and water. Importantly, low CO 2 adsorption heat (26.5 kJ mol−1) makes Zn-dmtrz-mip can be easily regenerated by inert gas purging and maintain its separation performance over five repeat process cycles. Molecule simulation revealed the crucial role of methyl groups through multiple C-H···O interactions for such high CO 2 uptake capacity and separation selectivity. [ABSTRACT FROM AUTHOR]

Two new Ag(I) complexes with 1,3-bis(imidazol-1-ylmethyl)benzene (L1) and 1,3-bis(imidazol-1-ylmethyl)-5-methylbenzene (L2), namely {[AgL1]CF3SO3}n (1) and {[AgL2]CF3SO3}n (2), were synthesised and characterised by SCXRD to uncover the effect that introducing a methyl group to the benzene core of the ligand has on the molecular/crystal structure of the metal complex. The studies revealed a high level of isostructurality of the formed Ag(I) complexes, consisting of 1D cationic chains with the charge neutralised by the counterions applied. These results triggered structural investigations of the parent ligands, which, as revealed by SCXRD, crystallise as dihydrates in different space groups of a monoclinic system. Further analyses revealed that the motifs in their molecular packing in general stay the same. However, some morphotropic/positional adjustments are taking place in L2 to accommodate the presence of the methyl substituent. [ABSTRACT FROM AUTHOR]

The synthesis and crystal structure of peptide 6,60-dimethyl biphenyl hybrid are described. The title compound was synthesized by reaction between 6,60- dimethyl-[1,1'-biphenyl]-2,2'-dicarbonyl dichloride in CH2Cl2, amine HN-- proline--phenylalanine--alanine--COOMe and Et3N at 273 K under N2 atmosphere and characterized by single-crystal X-ray diffraction. The asymmetric unit contains one peptide molecule and a quarter of a water molecule. A disorder of a methyl and methoxycarbonyl group of one alanine residue is observed with occupancy ratio 0.502 (6):0.498 (6). The structure is consolidated by intra- and intermolecular hydrogen bonds. [ABSTRACT FROM AUTHOR]

The title alkali propano­ates poly[(μ5-propano­ato)alkali(I)], M+(C2H5COO)−, with alkali/M+ = Na+, K+, Rb+ and Cs+, show close structural similarity, which is manifested by the coordination of the cations by six oxygen atoms in a chessboard motif, forming a bilayer. This bilayer is situated between hydro­phobic layers composed of dangling ethyl chains from the carboxyl­ate groups. Stacking of these two-dimensional sandwiches, which are parallel to (001), forms the title structures. Each metal cation is coordinated by six O atoms in the form of a distorted trigonal prism. One pair of these oxygen atoms belongs to a bridging, bidentately coordinating carboxyl­ate anion, while each of the other four oxygen atoms belongs to different carboxyl­ate groups, which are in a bridging monodentate mode. Despite the close similarity, each of the studied alkali propano­ates crystallizes in a different space group. The atoms are in general positions, except for the cation in K+(C2H5COO)−, which is situated on a mirror plane. Positional disorder of the methyl groups that are disordered over two positions is present in the Na+ and K+ propano­ates, in contrast to the Rb+ and Cs+ propano­ates. In the Na+ compound, the occupational parameters of the disordered methyl groups are different compared to the K+ compound where they are equal. This difference results in doubling of the a unit-cell parameter of the Na+ compound with respect to that of the K+ compound, otherwise the structures are homeotypic. In Cs+ propano­ate, a disorder of the methyl H atoms is observed. [ABSTRACT FROM AUTHOR]

The title alkali propano­ates poly[(μ5-propano­ato)alkali(I)], M+(C2H5COO)−, with alkali/M+ = Na+, K+, Rb+ and Cs+, show close structural similarity, which is manifested by the coordination of the cations by six oxygen atoms in a chessboard motif, forming a bilayer. This bilayer is situated between hydro­phobic layers composed of dangling ethyl chains from the carboxyl­ate groups. Stacking of these two-dimensional sandwiches, which are parallel to (001), forms the title structures. Each metal cation is coordinated by six O atoms in the form of a distorted trigonal prism. One pair of these oxygen atoms belongs to a bridging, bidentately coordinating carboxyl­ate anion, while each of the other four oxygen atoms belongs to different carboxyl­ate groups, which are in a bridging monodentate mode. Despite the close similarity, each of the studied alkali propano­ates crystallizes in a different space group. The atoms are in general positions, except for the cation in K+(C2H5COO)−, which is situated on a mirror plane. Positional disorder of the methyl groups that are disordered over two positions is present in the Na+ and K+ propano­ates, in contrast to the Rb+ and Cs+ propano­ates. In the Na+ compound, the occupational parameters of the disordered methyl groups are different compared to the K+ compound where they are equal. This difference results in doubling of the a unit-cell parameter of the Na+ compound with respect to that of the K+ compound, otherwise the structures are homeotypic. In Cs+ propano­ate, a disorder of the methyl H atoms is observed. [ABSTRACT FROM AUTHOR]

The asymmetric unit of the title compound, C11H12N2O2·H2O, contains a mol­ecule of 1,4,6-trimethyl-1,4-di­hydro­quinoxaline-2,3-dione and a solvent water mol­ecule. Four atoms of the benzene ring are disordered over two sets of sites in a 0.706 (7):0.294 (7) ratio while the N-bound methyl groups are rotationally disordered with occupancy ratios of 0.78 (4):0.22 (4) and 0.76 (5):0.24 (5). In the crystal, mol­ecules are linked by O—HO and C—HO hydrogen bonds into layers lying parallel to (10). The Hirshfeld surface analysis indicates that the most important contributions to the packing arrangement are due to HH (51.3%) and OH/HO (28.6%) inter­actions. The mol­ecular structure calculated by density functional theory is compared with the experimentally determined mol­ecular structure, and the HOMO–LUMO energy gap has been calculated. [ABSTRACT FROM AUTHOR]

The title compounds, 2,6-diiodo-4-nitrotoluene (DINT, C7H5I2NO2) and 2,4,6- tribromotoluene (TBT, C7H5Br3,), are trisubstituted toluene molecules. Both molecules are planar, only the H atoms of the methyl group, and the nitro group in DINT, deviate significantly from the plane of the benzene ring. In the crystals of both compounds, molecules stack in columns up the shortest crystallographic axis, viz. the a axis in DINT and the b axis in TBT. In the crystal of DINT, molecules are linked via short N—OI contacts, forming chains along [100]. In TBT, molecules are linked by C—HBr hydrogen bonds, forming chains along [010]. Hirshfeld surface analysis was used to explore the intermolecular contacts in the crystals of both DINT and TBT. [ABSTRACT FROM AUTHOR]