scholarly journals Host–guest complexes of conformationally flexible C-hexyl-2-bromoresorcinarene and aromatic N-oxides: solid-state, solution and computational studies

2018 ◽  
Vol 14 ◽  
pp. 1723-1733 ◽  
Author(s):  
Rakesh Puttreddy ◽  
Ngong Kodiah Beyeh ◽  
S Maryamdokht Taimoory ◽  
Daniel Meister ◽  
John F Trant ◽  
...  
Keyword(s):  
Solid State ◽  
Conformational Changes ◽  
Form Solution ◽  
Solution Phase ◽  
Computational Studies ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Additional Stability ◽  
Electron Donating Groups

Host–guest complexes of C-hexyl-2-bromoresorcinarene (BrC6) with twelve potential aromatic N-oxide guests were studied using single crystal X-ray diffraction analysis and 1H NMR spectroscopy. In the solid state, of the nine obtained X-ray crystal structures, eight were consistent with the formation of BrC6-N-oxide endo complexes. The lone exception was from the association between 4-phenylpyridine N-oxide and BrC6, in that case the host forms a self-inclusion complex. BrC6, as opposed to more rigid previously studied C-ethyl-2-bromoresorcinarene and C-propyl-2-bromoresorcinarene, undergoes remarkable cavity conformational changes to host different N-oxide guests through C–H···π(host) interactions. In solution phase CD3OD/CDCl3 (1:1 v/v), all twelve N-oxide guests form endo complexes according to 1H NMR; however, in more polar CD3OD/DMSO-d 6 (9:1 v/v), only three N-oxides with electron-donating groups form solution-phase endo complexes with BrC6. In solid-state studies, 3-methylpyridine N-oxide+BrC6 crystallises with both the upper- and lower-rim BrC6 cavities occupied by N-oxide guests. Computational DFT-based studies support that lower-rim long hexyl chains provide the additional stability required for this ditopic behaviour. The lower-rim cavity, far from being a neutral hydrophobic environment, is a highly polarizable electrostatically positive surface, aiding in the binding of polar guests such as N-oxides.

Chemistry of zwitterionic penta-coordinate silicon compounds of the (ammoniomethyl)bis[glycolato(2–)-O1,O2]silicate type in aqueous and nonaqueous solution

2003 ◽  
Vol 81 (11) ◽  
pp. 1315-1325 ◽  
Author(s):  
Reinhold Tacke ◽  
Rüdiger Bertermann ◽  
Andreas Biller ◽  
Christian Burschka ◽  
Martin Penka
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Computational Chemistry ◽  
Experimental Investigations ◽  
Computational Studies ◽  
X Ray Diffraction ◽  
Model Species ◽  
Silicon Compounds ◽  
X Ray ◽  
H Nmr

The zwitterionic spirocyclic λ5Si-silicates bis[glycolato(2–)-O1,O2][(trimethylammonio)methyl]silicate ([OCH2C(O)O]2SiCH2NMe3, 3) and bis[2-methyllactato(2–)-O1,O2][(trimethylammonio)methyl]silicate ([OCMe2C(O)O]2SiCH2NMe3, 4) were synthesized by treatment of the zwitterionic λ5Si-silicate F4SiCH2NMe3 with 2 mol. equiv. of Me3SiOCR2C(O)OSiMe3 (R = H, Me) (formation of 4 mol. equiv. of Me3SiF). Compounds 3 (isolated as 3•2/3MeCN after drying in vacuo) and 4 were studied by solution 1H, 13C, and 29Si NMR spectroscopy and by solid-state VACP/MAS 13C, 15N, and 29Si NMR experiments, and the solvates 3•MeCN and 4•2MeCN were structurally characterized by single-crystal X-ray diffraction. These experimental investigations were complemented by computational studies of the zwitterions 3 and 4 and the anionic model species bis[2-methyllactato(2–)-O1,O2]hydridosilicate(1–) ([OCMe2C(O)O]2SiH–, 8). Compounds 3•2/3MeCN and 4 and their already known derivatives [OCH2C(O)O]2SiCH2NMe2H (1) and [OCMe2C(O)O]2SiCH2NMe2H (2) were studied for their dynamic behavior (Λ/Δ-enantiomerization) in solution by VT 1H NMR spectroscopy. In addition, compounds 1, 2, 3•2/3MeCN, and 4 were studied in CD3OD and D2O with 1H, 13C, and 29Si NMR experiments.Key words: penta-coordinate silicon, zwitterionic λ5Si-silicates, Λ/Δ-enantiomerism, NMR spectroscopy, computational chemistry.

Investigation of the disorder of dibromo- and dichloromethane in their tri-ortho-thymotide clathrates using X-ray diffraction and solid-state 2H NMR spectroscopy

2011 ◽  
Vol 89 (7) ◽  
pp. 854-862
Author(s):  
Glenn A. Facey ◽  
Ilia Korobkov
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Guest Molecule ◽  
Type B ◽  
X Ray Diffraction ◽  
Guest Molecules ◽  
X Ray ◽  
Twofold Axis ◽  
H Nmr ◽  
Heavy Atoms

The tri-ortho-thymotide (TOT) clathrates of dibromo- and dichloromethane were characterized by single crystal X-ray diffraction at 200 K and solid-state 2H NMR spectroscopy as a function of temperature. The host structure was found to be typical of other cage-type TOT clathrates. The X-ray results showed a substantial amount of disorder among the guest molecules. In both clathrates, multiple guest molecule positions could be modeled. The heavy atoms of all the guest molecule positions lie approximately in the same plane, with some out-of-plane distortion. The guest molecules were of two different types in positions symmetric about the crystallographic twofold rotation axis: type A guests, with carbon atoms well removed from the crystallographic twofold axis, and type B guests, with carbon atoms very close to the twofold axis. The 2H NMR spectra for the guests confirmed that the disorder was dynamic. The experimental results could be accounted for by the presence of three simultaneous types of molecular motion, all fast with respect to the 2H quadrupolar interaction: (i) twofold molecular flips about the molecular C2 symmetry axis, (ii) exchange between the type A and type B sites in a single plane, and (iii) a two-site libration of the plane containing the heavy atoms of the A and B guest sites with a temperature-dependent amplitude.

Sila-Pharmaka, 26. Mitt. [1]. Darstellung und Eigenschaften potentiell curarewirksamer Silicium-Verbindungen, III / Sila-Pharmaca, 26th Communication [1]. Preparation and Properties of Silicon Compounds with Potential Curare-Like Activity, III

1982 ◽  
Vol 37 (11) ◽  
pp. 1461-1471 ◽  
Author(s):  
Reinhold Tacke ◽  
Haryanto Linoh ◽  
Moayad T. Attar-Bashi ◽  
William S. Sheldrick ◽  
Ludger Ernst ◽  
...  
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Neuromuscular Blocking ◽  
Neuromuscular Blocking Agents ◽  
X Ray Diffraction ◽  
Silicon Compounds ◽  
X Ray ◽  
Structure Activity Relationships ◽  
H Nmr ◽  
Structure Activity

The potentially curare-like silicon compounds 8a-8f wore synthesized and investigated with respect to their structure-activity relationships. The conformations of the com­pounds in the solid state and in solution were studied by X-ray diffraction analysis (8a-8e) and 1H NMR spectroscopy (8a-8f), respectively. The muscle relaxing properties of 8a-8f were investigated on the mouse. The observed structure-activity relationships are not in accordance with the classical “14 Å model” for neuromuscular blocking agents.

Synthesis of Triferrocenylbenzenes by Tantalum(V)-Catalyzed Cyclotrimerization of Ethynylferrocene. The Crystal Structure of 1,3,5-Triferrocenylbenzene

1997 ◽  
Vol 62 (10) ◽  
pp. 1577-1584 ◽  
Author(s):  
Petr Štěpnička ◽  
Ivana Císařová ◽  
Jan Sedláček ◽  
Jiří Vohlídal ◽  
Miroslav Polášek
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Single Crystal ◽  
High Yield ◽  
Isomer Mixture ◽  
State Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Yield Formation

Exclusive, high-yield formation of the cyclotrimers of ethynylferrocene (1) was observed when TaCl5 in benzene was employed as catalyst. Analysis of the resulting isomer mixture by means of HPLC and 1H NMR revealed the presence of 1,3,5-triferrocenylbenzene (sym-2) and 1,2,4-triferrocenylbenzene (asym-2) in the ratio of 4 : 6. A small amount of pure sym-2 isomer was isolated, and its solid-state structure was established by single-crystal X-ray diffraction. The molecules of sym-2 possess a distorted up-up-down arrangement of the ferrocenyl groups attached to the benzene ring.

A bis-Au(III) [28]hexaphyrin triphenylphosphine adduct

2016 ◽  
Vol 20 (08n11) ◽  
pp. 997-1001 ◽  
Author(s):  
Koji Naoda ◽  
Atsuhiro Osuka
Keyword(s):  
Solid State ◽  
Structural Analysis ◽  
Trifluoroacetic Acid ◽  
X Ray Diffraction ◽  
Nmr Spectrum ◽  
X Ray ◽  
H Nmr ◽  
Detailed Structural Analysis ◽  
Nir Absorption ◽  
Plausible Mechanism

Triphenylphosphine was added regioselectively at the C(3) position of bis-Au(III) complex of [26]hexaphyrin 5 in the presence of trifluoroacetic acid to produce [28]hexaphyrin triphenylphosphine adduct 6 in 62% yield, which has been fully characterized by NMR, UV-vis/NIR absorption, and MS spectroscopies, and X-ray diffraction analysis. The rigid planar structure forces 6 to take Hückel antiaromaticity, which has been supported by its 1H NMR spectrum. Curiously, the detailed structural analysis elucidated that the triphenylphosphine moiety exists as a phosphorane form in the solid state. A plausible mechanism via a double protonated 5 is proposed, which can explain the observed regioselectivity.

A solid state NMR and X-ray crystallographic investigation of dynamic disorder in solid tetrahydronaphthalene derivatives

1996 ◽  
Vol 74 (10) ◽  
pp. 1844-1851 ◽  
Author(s):  
Glenn A. Facey ◽  
Terrence J. Connolly ◽  
Corinne Bensimon ◽  
Tony Durst
Keyword(s):  
Solid State ◽  
Solid State Nmr ◽  
X Ray Diffraction ◽  
Molecular Conformations ◽  
Dynamic Disorder ◽  
X Ray ◽  
H Nmr ◽  
Nmr Data ◽  
Deuterated Analog ◽  
Naphthoic Acid

The solid state disorder of two tetrahydronaphthalene derivatives, N-methyl-N-methoxy-5,6,7,8-tetrahydro-1-naphthamide and 5,6,7,8-tetrahydro-1-naphthoic acid, was studied by solid state NMR and single crystal X-ray diffraction. The X-ray crystal structure of N-methyl-N-methoxy-5,6,7,8-tetrahydro-1-naphthamide was obtained at 123 K. It indicated the presence of two distinct molecular conformations. Solid state 13C CP/MAS NMR data using the dipolar dephasing technique revealed that the two conformations of the molecule are dynamically disordered, while solid state 2H NMR data, collected on a specifically deuterated analog, were used to determine the populations of each conformation as well as an apparent activation energy. Solid state NMR experiments were also used to show that 5,6,7,8-tetrahydro-1-naphthoic acid possesses the same type of dynamic disorder. Key words: deuterium NMR, solid state NMR, dynamic disorder. X-ray, tetrahydronaphthalene derivatives

A multinuclear solid-state magnetic resonance study of silver nitrate triphenylphosphine

2005 ◽  
Vol 83 (10) ◽  
pp. 1721-1730 ◽  
Author(s):  
Se-Woung Oh ◽  
Guy M Bernard ◽  
Roderick E Wasylishen ◽  
Robert McDonald ◽  
Michael J Ferguson
Keyword(s):  
Phase Transition ◽  
Solid State ◽  
Single Crystal ◽  
Silver Nitrate ◽  
Solid Phase ◽  
Variable Temperature ◽  
Spin Coupling ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr

Variable-temperature solid-state 31P, 15N, and 2H NMR spectroscopy, X-ray diffraction, and differential scanning calorimetry studies of the 1:1 adduct of silver nitrate and triphenylphosphine (AgNO3·PPh3) reveal a solid–solid phase transition at 300 K. The principal components of the phosphorus and nitrogen chemical shift tensors for both phases are determined from NMR spectra of MAS and stationary samples. In addition, the indirect spin-spin coupling between phosphorus and the naturally occurring isotopes of silver (107Ag and 109Ag) are resolved. Experimental 2H NMR line shapes for silver nitrate perdeuterated triphenylphosphine are those characteristic of rigid phenyl groups at temperatures above and below the phase-transition temperature. Powder and single-crystal X-ray diffraction data for AgNO3·PPh3 obtained at 193, 295, and 313 K are reported; data obtained at 193 and 295 K are almost identical, but are significantly different from those obtained at 313 K and from an earlier single-crystal X-ray diffraction investigation performed at 298 K. All X-ray studies found that AgNO3·PPh3 crystallizes in the monoclinic form, space group P21/c.Key words: 1:1 silver nitrate triphenylphosphine adduct, solid-state NMR, X-ray diffraction, phase transition.

Synthesis and Crystal Structures of New 1,4-Disubstituted 1,2,4-Triazoline-5-thiones

2014 ◽  
Vol 69 (9-10) ◽  
pp. 950-964 ◽  
Author(s):  
Gerhard Laus ◽  
Volker Kahlenberg ◽  
Klaus Wurst ◽  
Herwig Schottenberger
Keyword(s):  
Solid State ◽  
Crystal Structures ◽  
Significant Contribution ◽  
Chemical Shifts ◽  
Resonance Structure ◽  
X Ray Diffraction ◽  
Reference Compound ◽  
Intermolecular Hydrogen Bonds ◽  
X Ray ◽  
H Nmr

AbstractIntroduction of sulfur into the 5-position of 1,4-disubstituted quaternary 1,2,4-triazolium salts (1-9; Cl, Br, I, BF4, PF6, CH3OSO3 were used as anions) by two methods was investigated. The syntheses of nine 1,4-disubstituted 1,2,4-triazoline-5-thiones 10-18 are reported (1, 10: R1 = CH3, R2 = CH3; 2, 11: R1 = NH2, R2 = CH3; 3, 12: R1 = NH2, R2 = CH(CH3)2; 4, 13: R1 = N(CH3)2, R2 = CH3; 5, 14: R1 = N(CH3)2, R2 = CH(CH3)2; 6, 15: R1 = CH3, R2 = NH2; 7, 16: R1 = OCH2Ph, R2 = CH3; 8, 17: R1 = OCH2Ph, R2 = CH2CH3; 9, 18: R1 = CH3, R2 = CH2Ph). Compounds 11-17 represent 1-amino, 4-amino, 4-dimethylamino, and 4-benzyloxy-1,2,4-triazoline-5- thiones, whereas 10 served as a reference compound. Thione 18 was identified as an unexpected by-product in the synthesis of 16 and was also prepared independently. Thermolysis of 10 in air gave 1,4-dimethyl-1,2,4-triazolium hydrogensulfate. Crystal structures of eight 1,4-disubstituted 1,2,4- triazoline-5-thiones were determined by single-crystal X-ray diffraction. Intermolecular hydrogen bonds (C-H···S, C-H···N, N-H···N, N-H···S) were observed in the solid state. The solvent-dependent 1H NMR chemical shifts of signals of 10 and 13 were satisfactorily correlated with the Kamlet- Abboud-Taft π* and b parameters in ten solvents. From the lack of correlation with the a parameter and from the C=S bond length (average 1.67 Å) a significant contribution of a mesoionic imidazolium-2-thiolate resonance structure seems unlikely

NMR and X-ray Diffraction Study of the Conformational Structure of Poly[N5-(2-hydroxyethyl)-L-glutamine] and Poly[N5-(2-hydroxyethyl)-L-glutamine-co-γ-L-glutamylhydrazide]

1993 ◽  
Vol 58 (10) ◽  
pp. 2415-2427
Author(s):  
Drahomíra Hlavatá ◽  
Hana Pivcová ◽  
Jiří Spěváček ◽  
Dagmar Nosková ◽  
František Rypáček
Keyword(s):  
Solid State ◽  
Benzyl Ester ◽  
Dichloroacetic Acid ◽  
Random Coil ◽  
Conformational Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Nmr Spectrometry ◽  
Cp Mas Nmr

The conformation of poly[N5-(2-hydroxyethyl)L-glutamine] (P(HEG-GH)), in solid state was studied by 13C CP/MAS NMR spectrometry and X-ray diffraction. The association of copolymers in dichloroacetic acid was investigated by following the temperature dependence of their 1H NMR spectra, PHEG and P(HEG-GH) were prepared by the reaction of poly(benzyl γ-L-glutamate) with 2-aminoethanol and 2-aminoethanol-hydrazine mixtures, respectively. The conformation of the copolymers depends on the reaction conditions. While PHEG and the copolymers prepared with the mole ratio of hydrazine to the benzyl ester nH/nB = 0.25 were almost amorphous in solid state and had a random coil conformation and/or randomly oriented helices, at increased concentration of hydrazine (nH/nB = 0.5 and 1.0) P(HEG-GH) formed more or less ordered structure characterized by assemblies of α-helices. The copolymers prepared at nH/nB 3 2.0 showed features of β-sheets. The tendency of the copolymers to form associates in Cl2CHCOOH solutions correlated well with their tendency to form ordered structures in solid state.

A photodimer of a 4-phenyl-4H-pyran

2006 ◽  
Vol 62 (5) ◽  
pp. o1951-o1953 ◽  
Author(s):  
Hong Yan ◽  
Hui-Qin Wang ◽  
Cheng-Liang Ni ◽  
Xiu-Qing Song
Keyword(s):  
Molecular Structure ◽  
Crystal Structure ◽  
Hydrogen Bond ◽  
Solid State ◽  
Mass Spectroscopy ◽  
Elemental Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
H Nmr ◽  
Hydrogen Bond Interactions

A new cage photodimer, tetraethyl 2,4,8,10-tetramethyl-6,12-diphenyl-3,9-dioxapentacyclo[6.4.0.02,7.04,11.05,10]dodecane-1,5,7,11-tetracarboxylate, C38H44O10, was prepared through [2+2]-photocycloaddition of diethyl 2,6-dimethyl-4-phenyl-4H-pyran-3,5-dicarboxylate in the solid state. The molecular structure was elucidated by X-ray diffraction analysis, 1H NMR, IR and mass spectroscopy, and elemental analysis. The molecule possesses a crystallographically imposed centre of symmetry. The crystal structure is stabilized by weak C—H...O hydrogen-bond interactions.

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