scholarly journals Hydrothermal synthesis and structure of a new layered zincophosphate intercalated with 3-methylaminopropylamine cations

2005 ◽  
Vol 70 (4) ◽  
pp. 625-634 ◽  
Author(s):  
Nevenka Rajic ◽  
Natasa Zabukovec-Logar ◽  
Djordje Stojakovic ◽  
Sanja Sajic ◽  
Amalija Golobic ◽  
...  
Keyword(s):  
Activation Energy ◽  
Hydrothermal Synthesis ◽  
Hydrogen Bonds ◽  
Negative Charge ◽  
Membered Ring ◽  
Hydroxyl Groups ◽  
Hydrothermal Crystallization ◽  
Structure Directing Agent

A novel layered zincophosphate (ZnPO?MPA) was prepared by hydrothermal crystallization using 3-methylaminopropylamine (MPA) as a structure-directing agent. The structure consists of macroanion [Zn2P3O8(OH)3]2- layers which are built up of 4-membered ring channels. The channels (of about 3.7 ? diameter) arise through the connection of the neighbouring rings by two oxygen bridges. The negative charge of the layers is compensated by diprotonated MPA molecules which are stacked parallel to the ring channels. ZnPO?MPA is stable up to 300 ?C. At higher temperatures MPA decomposition begins followed by a dehydration, which occurs through condensation of the framework hydroxyl groups. The activation energy of the MPA decomposition is high due to the fact that the layers and MPA cations are held together by strong hydrogen bonds.

Methyl 4-O-pivaloyl-β-D-xylopyranoside

2006 ◽  
Vol 62 (7) ◽  
pp. o2746-o2748
Author(s):  
Vesna Petrović ◽  
Ivan Halasz ◽  
Srđanka Tomić ◽  
Dubravka Matković Čalogović
Keyword(s):  
Hydrogen Bonds ◽  
Title Compound ◽  
Chair Conformation ◽  
Membered Ring ◽  
Hydroxyl Groups ◽  
Equatorial Position ◽  
Dimensional Chain ◽  
One Dimensional ◽  
Compound C

The six-membered ring of the title compound, C11H20O6, adopts the chair conformation, with the 4-O-pivaloyl group in an equatorial position. Two vicinal hydroxyl groups of each molecule form four hydrogen bonds of the O—H...O type in a one-dimensional chain running along the b axis.

scholarly journals Diol Mediated Tautomerization of Glycine: a DFT Study

2019 ◽  
Vol 16 (1) ◽  
pp. 33-39
Author(s):  
Francis Suh ◽  
Vanessa Rivera ◽  
Ruben Parra
Keyword(s):  
Activation Energy ◽  
Aqueous Solution ◽  
Hydrogen Bonds ◽  
Proton Transfer ◽  
Gas Phase ◽  
Activation Energies ◽  
Dft Study ◽  
Hydroxyl Groups ◽  
Neutral Process ◽  
Product Forms

The tautomerization of glycine via a triple proton transfer was investigated both in the gas phase and in aqueous solution using the B3LYP/6-31+G(d,p) level of theory. Fully optimized complexes of the neutral and zwitterion forms of glycine with 1,3-propanediol were used for the reactant and product forms, respectively. The hydroxyl groups in the diol are conveniently oriented for glycine tautomerization through a concerted triple proton transfer facilitated by a network of three hydrogen bonds: N-H…O-H…O-H…O=C. The activation energy for the zwitterion à neutral process increases in solution. Also, the diol-glycine complex favors the neutral over the zwitterion form in a vacuum, but the opposite is true in solution. For comparative purposes, the tautomerization of glycine via a three-proton transfer mediated by two molecules of water was also examined. The results are qualitatively similar, albeit with activation energies that are smaller to those found in the corresponding diol-mediated tautomerization. KEYWORDS: Glycine; zwitterion, diol-mediated tautomerization; water-mediated tautomerization

On the structural diversity anions coordinate to the butterfly-shaped [(R2Sn)3O(OH)2]2+ cations and vice versa

2014 ◽  
Vol 92 (6) ◽  
pp. 496-507 ◽  
Author(s):  
Hans Reuter ◽  
Hilko Wilberts
Keyword(s):  
Hydrogen Bonds ◽  
Iodine Atom ◽  
Structural Parameters ◽  
Structural Diversity ◽  
Hydroxyl Groups ◽  
Equatorial Position ◽  
Chelating Ligands ◽  
Trigonal Bipyramidal Coordination ◽  
Trigonal Bipyramidal ◽  
Oxygen Framework

The syntheses and crystal structures of [(t-Bu2Sn)3O(OH)2]CO3·3MeOH, 1a, [(t-Bu2Sn)3O(OH)2]CO3·3H2O·acetone, 1b, [(t-Bu2Sn)3O(OH)2][I]2·[(t-Bu2Sn(OH)I]2·2DMSO, 1c, and [(Cy2Sn)3O(OH)2][I]2·2DMSO, 2a, all containing the trinuclear [(R2Sn)3O(OH)2]2+ ion have been described. The butterfly shape of this cation is derived from two annulated, four-membered tin–oxygen rings with a central μ3-oxygen atom and trigonal-bipyramidally coordinated tin atom both belonging to both rings and two μ2-hydroxyl groups and two outer, four-fold coordinated tin atoms. In 1a and 1b, the carbonate anions interact with the outer tin atoms of the cations as bidentate chelating ligands in the classical syn–syn coordination mode, and vice versa. In this way, both outer tin atoms expand their coordination sphere from four to five, with the consequence that bond angles and lengths within the cation are determined by the axial and equatorial position of the oxygen atoms within the trigonal-bipyramidal coordination on all three tin atoms. 1c consists of two different building units, an up to now unknown hydroxide iodide of composition [(t-Bu2Sn(OH)I]2 with hydrogen-bonded DMSO molecules and a [(t-Bu2Sn)3O(OH)2]2+ cation with one coordinated and one isolated, via hydrogen bonds connected iodine ion. The hydroxide iodine is built up of two five-fold coordinated tin atoms linked via two hydroxyl groups with exocyclic iodine atoms occupying axial positions at the trigonal-biypramidally coordinated tin atoms. The unprecedented coordination of the iodine ion to the [(t-Bu2Sn)3O(OH)2]2+ cation takes place between both outer tin atoms, resulting in a five-fold, trigonal-bipyramidal coordination at these tin atoms, too. Structural parameters within the so-formed [(t-Bu2Sn)3O(OH)2I]+ complex are very similar to those of 1a and 1b, with the exception of a significant lengthening of the tin–oxygen bonds opposite to the bridging iodine atom. 2a represents the first example of the [(R2Sn)3O(OH)2]2+ cation without R = t-butyl, so far. In the solid, it consists of two crystallographic independent [(Cy2Sn)3O(OH)2][I]2 building units, each connected to two DMSO molecules via hydrogen bonds. Both building units are very similar with respect to their conformation. Each of the iodine anions coordinates with only one of the two outer tin atoms, one in an inwards, one in an outwards to the tin-oxygen framework directed position. These tin atoms are therefore also trigonal-bipyramidally coordinated as in 1a−1c, but because of steric reasons one of the trigonal-bipyramids has changed its orientation within the tin–oxygen framework, accompanied by enormous changes of bond lengths and angles therein.

Hydrothermal synthesis of flower cluster-shaped ZnO microstructures with sodium lignosulfonate as structure-directing agent

2015 ◽  
Vol 26 (11) ◽  
pp. 9171-9177
Author(s):  
Chen Hao ◽  
Huailiang Zhang ◽  
Xiaohong Wang ◽  
Yuru Shen ◽  
Yinglu Yang ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Sodium Lignosulfonate ◽  
Structure Directing Agent

Hydrothermal synthesis of Sn-Beta zeolites in F−-free medium

2018 ◽  
Vol 5 (11) ◽  
pp. 2763-2771 ◽  
Author(s):  
Hao Xu ◽  
Xudong Wang ◽  
Peng Ji ◽  
Haihong Wu ◽  
Yejun Guan ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Lewis Acid ◽  
Crystal Size ◽  
Acid Catalysts ◽  
Free Medium ◽  
Lewis Acid Catalysts ◽  
Structure Directing Agent ◽  
Highly Active ◽  
Beta Zeolites

Sn-Beta zeolites, with high Sn content and smaller crystal size, hydrothermally synthesized in F−-free medium using N-cyclohexyl-N,N-dimethylcyclohexanaminium hydroxide as the structure-directing agent with the assistance of Na+ and seed, are highly active as Lewis acid catalysts.

scholarly journals 14,15-Didehydrohellebrigenin

2012 ◽  
Vol 68 (6) ◽  
pp. o1614-o1615
Author(s):  
Tong Yu ◽  
Hai-Yan Tian ◽  
Xiao-Feng Yuan ◽  
Shu-Zhi Hu ◽  
Ren-Wang Jiang
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Title Compound ◽  
Lactone Ring ◽  
Three Dimensional ◽  
Membered Ring ◽  
Envelope Conformation ◽  
Compound C ◽  
Dimensional Network ◽  
Hydroxy Groups

The title compound, C24H30O5, is the didehydro product of the steroid hellebrigenin (systematic name: 3β,5,14-trihydroxy-19-oxo-5β-bufa-20,22-dienolide). It consists of three cyclohexane rings (A, B and C), a five-membered ring (D) and a six-membered lactone ring (E). The stereochemistry of the ring junctions are A/B cis, B/C trans and C/D cis. Cyclohexane rings A, B and C have normal chair conformations. The five-membered ring D with the C=C bond adopts an envelope conformation. Lactone ring E is essentially planar with a mean derivation of 0.006 (4) Å and is β-oriented at the C atom of ring D to which it is attached. There is an O—H...O hydrogen bond in the molecule involving the hydroxy groups. In the crystal, O—H...O hydrogen bonds link the molecules into chains propagating along [010]. The chains are linked by C—H...O contacts into a three-dimensional network.

Nitrocellulose Catalyzed With Manganese Oxide Nanoparticles: Advanced Energetic Nanocomposite With Superior Decomposition Kinetics

2021 ◽  
Author(s):  
Sherif Elbasuney ◽  
M. Yehia ◽  
Shukri Ismael ◽  
Yasser El-Shaer ◽  
Ahmed Saleh
Keyword(s):  
Activation Energy ◽  
Particle Size ◽  
Manganese Oxide ◽  
Energetic Materials ◽  
Average Particle Size ◽  
Active Surface ◽  
Propagation Rate ◽  
Hydroxyl Groups ◽  
Average Particle ◽  
Decomposition Enthalpy

Abstract Nanostructured energetic materials can fit with advanced energetic first-fire, and electric bridges (microchips). Manganese oxide, with active surface sites (negatively charged surface oxygen, and hydroxyl groups) can experience superior catalytic activity. Manganese oxide could boost decomposition enthalpy, ignitability, and propagation rate. Furthermore manganese oxide could induce vigorous thermite reaction with aluminium particles. Hot solid or liquid particles are desirable for first-fire compositions. This study reports on the facile fabrication of MnO2 nanoparticles of 10 nm average particle size; aluminium nanoplates of 100 nm average particle size were employed. Nitrocellulose (NC) was adopted as energetic polymeric binder. MnO2/Al particles were integrated into NC matrix via co-precipitation technique. Nanothermite particles offered an increase in NC decomposition enthalpy by 150 % using DSC; ignition temperature was decreased by 8 0C. Nanothemrite particles offered enhanced propagation index by 261 %. Kinetic study demonstrated that nanothermite particles experienced drastic decrease in NC activation energy by - 42, and - 40 KJ mol-1 using Kissinger and KAS models respectively. This study shaded the light on novel nanostructured energetic composition, with superior combustion enthalpy, propagation rate, and activation energy.

scholarly journals Crystal structure of creatininium 5-(2,4-dinitrophenyl)-1,3-dimethylbarbiturate monohydrate: a potential anticonvulsant agent

2016 ◽  
Vol 72 (5) ◽  
pp. 620-623
Author(s):  
Ponnusamy Poornima Devi ◽  
Doraisamyraja Kalaivani
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Water Molecule ◽  
Three Dimensional ◽  
Pyrimidine Ring ◽  
Membered Ring ◽  
Anticonvulsant Agent ◽  
The Mean ◽  
Anions And Cations ◽  
Molecular Salt

In the anion of the title hydrated molecular salt, C4H8N3O+·C12H9N4O7−·H2O [systematic name: 2-amino-1-methyl-4-oxo-4,5-dihydro-1H-imidazol-3-ium 5-(2,4-dinitrophenyl)-1,3-dimethyl-2,6-dioxo-1,2,3,6-tetrahydropyrimidin-4-olate monohydrate], the 2,4-dinitrophenyl ring is inclined to the mean plane of the pyrimidine ring [r.m.s. deviation = 0.37 Å] by 43.24 (8)°. The five-membered ring of the creatininium cation (2-amino-1-methyl-4-oxo-4,5-dihydro-1H-imidazol-3-ium) is essentially planar with an r.m.s. deviation of 0.015 Å. In the crystal, the anions and cations are linkedviaN—H...O hydrogen bonds, forming sheets parallel to theabplane. The sheets are linkedviaO—H...O hydrogen bonds involving the water molecule, forming a three-dimensional framework. Within the framework, there are C—H...O hydrogen bonds present. The title molecular salt displays anticonvulsant and hypnotic activities.

Synthesis, crystal structure and molecular conformation of (±)-1-oxoferruginol and (±)-shonanol

2004 ◽  
Vol 219 (10) ◽  
Author(s):  
Swastik Mondal ◽  
Monika Mukherjee ◽  
Arnab Roy ◽  
Debabrata Mukherjee
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Diffraction Data ◽  
Molecular Conformation ◽  
Membered Ring ◽  
Methyl Groups ◽  
Single Bond ◽  
X Ray Diffraction ◽  
X Ray ◽  
Chemical Structures

Abstract(±)-1-oxoferruginol and (±)-shonanol, two potential intermediates in the synthesis of tricyclic diterpenoid ferruginol, have been prepared and crystal structures of the compounds have been investigated using single-crystal X-ray diffraction data. The methyl groups of the isopropyl moiety in (±)-shonanol are disordered over two positions with occupation factors 0.65(1) and 0.35(1), respectively. Although the chemical structures of two compounds are very similar, a C—C single bond in the terminal six-membered ring of (±)-1-oxoferruginol is replaced by a C=C bond in (±)-shonanol, the quantitative isostructurality index calculations indicate that the structures are not isostructural. Intermolecular O—H…O hydrogen bonds between pairs of molecules in the compounds related by center of inversion lead to characteristic dimers forming R

Crystal structure of rivastigmine hydrogen tartrate Form I (Exelon®), C14H23N2O2(C4H5O6)

2016 ◽  
Vol 31 (2) ◽  
pp. 97-103 ◽  
Author(s):  
James A. Kaduk ◽  
Kai Zhong ◽  
Amy M. Gindhart ◽  
Thomas N. Blanton
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Powder Diffraction ◽  
Density Functional ◽  
Carbonyl Oxygen ◽  
Strong Hydrogen Bond ◽  
Hydroxyl Groups ◽  
A Chain ◽  
Tartrate Anion

The crystal structure of rivastigmine hydrogen tartrate has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional techniques. Rivastigmine hydrogen tartrate crystallizes in space group P21 (#4) with a = 17.538 34(5), b = 8.326 89(2), c = 7.261 11(2) Å, β = 98.7999(2)°, V = 1047.929(4) Å3, and Z = 2. The un-ionized end of the hydrogen tartrate anions forms a very strong hydrogen bond with the ionized end of another anion to form a chain. The ammonium group of the rivastigmine cation forms a strong discrete hydrogen bond with the carbonyl oxygen atom of the un-ionized end of the tartrate anion. These hydrogen bonds form a corrugated network in the bc-plane. Both hydroxyl groups of the tartrate anion form intramolecular O–H⋯O hydrogen bonds. Several C–H⋯O hydrogen bonds appear to contribute to the crystal energy. The powder pattern is included in the Powder Diffraction File™ as entry 00-064-1501.

Sign in / Sign up

Export Citation Format

Share Document