Linear oligopeptides. 118. Preferred conformations and modes of self-association of the fluoren-9-ylmethoxycarbonyl amino acid derivatives

1984 ◽  
Vol 62 (12) ◽  
pp. 2661-2666 ◽  
Author(s):  
Giovanni Valle ◽  
Gian Maria Bonora ◽  
Claudio Toniolo
Keyword(s):  
Solid State ◽  
Amide Bond ◽  
Experimental Result ◽  
Carbonyl Groups ◽  
Protecting Group ◽  
X Ray Diffraction ◽  
Aminoisobutyric Acid ◽  
Self Association ◽  
Associated Species ◽  
Derivatives Of

An analysis of the preferred conformations and modes of self-association of the N-fluoren-9-methoxycarbonyl derivatives of L-alanine and α-aminoisobutyric acid was performed in solution and in the solid state using infrared absorption, 1H nuclear magnetic resonance, and X-ray diffraction. In a solvent of low polarity (deuterochloroform) non-associated and self-associated species (involving predominantly the hydroxyl and carbonyl groups of the carboxylic acid moiety) simultaneously occur. At high dilution, where self-association is absent, the amount of intramolecularly H-bonded forms, if any, should be extremely small. Z(trans) [Formula: see text]E(cis) isomerism about the amide bond of the secondary urethane moiety was observed only for the less bulky L-alanine derivative. In the solid state all H-bonding donors and acceptors of the L-alanine and α-aminoisobutyric acid derivatives take part to complex schemes of intermolecular H-bonds. In the L-alanine derivative, crystallized as monohydrate, most of the intermolecular H-bonds involve the water molecule. Intramolecular H-bonds are not observed in either compound. The conformation about the secondary urethane CO—NH bond is Z(trans) in both compounds. Both L-alanine and α-aminoisobutyric acid residues are partially folded. The observation of the long C(sp3)—O bond of the fluoren-9-yl-methoxycarbonyl moiety might contribute to explain the unexpected experimental result that this protecting group can be removed by catalytic hydrogenation.

scholarly journals Bis(dicarbollide) Complexes of Transition Metals as a Platform for Molecular Switches. Study of Complexation of 8,8′-Bis(methylsulfanyl) Derivatives of Cobalt and Iron Bis(dicarbollides)

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5745
Author(s):  
Sergey A. Anufriev ◽  
Sergey V. Timofeev ◽  
Alexei A. Anisimov ◽  
Kyrill Yu. Suponitsky ◽  
Igor B. Sivaev
Keyword(s):  
Solid State ◽  
Transition Metal ◽  
Molecular Switches ◽  
X Ray Diffraction ◽  
Chelate Complexes ◽  
X Ray ◽  
Complexes Of Transition Metals ◽  
Silver Palladium ◽  
Solid State Structures ◽  
Derivatives Of

Complexation of the 8,8′-bis(methylsulfanyl) derivatives of cobalt and iron bis(dicarbollides) [8,8′-(MeS)2-3,3′-M(1,2-C2B9H10)2]− (M = Co, Fe) with copper, silver, palladium and rhodium leads to the formation of the corresponding chelate complexes, which is accompanied by a transition from the transoid to the cisoid conformation of the bis(dicarbollide) complex. This transition is reversible and can be used in design of coordination-driven molecular switches based on transition metal bis(dicarbollide) complexes. The solid-state structures of {(Ph3P)ClPd[8,8′- (MeS)2-3,3′-Co(1,2-C2B9H10)2-κ2-S,S′]} and {(COD)Rh[8,8′-(MeS)2-3,3′-Co(1,2-C2B9H10)2-κ2-S,S′]} were determined by single crystal X-ray diffraction.

Single-crystal and powder X-ray diffraction and solid-state 13C NMR of p-nitrophenyl glycopyranosides, the derivatives of d-galactose, d-glucose, and d-mannose

2009 ◽  
Vol 344 (13) ◽  
pp. 1734-1744 ◽  
Author(s):  
Tomasz Gubica ◽  
Andrzej Temeriusz ◽  
Katarzyna Paradowska ◽  
Andrzej Ostrowski ◽  
Paulina Klimentowska ◽  
...  
Keyword(s):  
Solid State ◽  
Single Crystal ◽  
13C Nmr ◽  
X Ray Diffraction ◽  
X Ray ◽  
Derivatives Of ◽  
Solid State 13C Nmr

Self-association and stereochemistry study of 2-methylthio-, 2-dimethylaminocyclohexanone oximes and the parent cyclohexanone oxime

2001 ◽  
Vol 57 (5) ◽  
pp. 705-713 ◽  
Author(s):  
Paulo R. Olivato ◽  
Douglas S. Ribeiro ◽  
J. Zukerman-Schpector ◽  
Gabriella Bombieri
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Parent Compound ◽  
Chair Conformation ◽  
Orbital Interaction ◽  
Cyclohexanone Oxime ◽  
X Ray Diffraction ◽  
X Ray ◽  
Shift Analysis ◽  
Self Association

X-ray diffraction analyses of 2-substituted cyclohexanone oximes C5H9(X)C=NOH [X = SMe (1), NMe2 (2)] and of the parent compound [X = H (3)] showed that their cyclohexyl rings are in a slightly distorted chair conformation. These compounds assume in the solid state the (E) configuration bearing the 2-substituents in the axial conformation. Compounds (1) and (2) exist as dimeric and polymeric hydrogen-bond associates, respectively. Low-temperature X-ray analysis of the cyclohexanone oxime (3) showed that the molecules are associated forming two independent trimers. The dimer in (1) and the trimer in (3) are built up via [O—H...N=C] hydrogen bonds, while the polymer of (2) is via the [OH...NMe2] hydrogen bond. The comparative IR νOH and νC=N analysis of the title compounds, in the solid state and in CCl4 solution, fully supports the nature of the associates for (1)–(3) obtained by X-ray diffraction. The IR azomethyne frequency shift analysis (ΔνC=N) also suggests the occurrence of the πC=N/σ*C—X orbital interaction which stabilizes the axial conformations of (1) and (2).

Generation and Stability of the gem-Diol Forms in Imidazole Derivatives Containing Carbonyl Groups. Solid-State NMR and Single-Crystal X-ray Diffraction Studies

2018 ◽  
Vol 122 (2) ◽  
pp. 601-609 ◽  
Author(s):  
Ayelén Florencia Crespi ◽  
Agustín Jesús Byrne ◽  
Daniel Vega ◽  
Ana Karina Chattah ◽  
Gustavo Alberto Monti ◽  
...  
Keyword(s):  
Solid State ◽  
Single Crystal ◽  
Solid State Nmr ◽  
Carbonyl Groups ◽  
X Ray Diffraction ◽  
X Ray ◽  
Imidazole Derivatives

Modes of Xanthine Complexation to Dirhodium Tetrakis[(R)-α-methoxy-α- (trifluoromethyl)-phenylacetate] in Solution and in the Solid State

2001 ◽  
Vol 56 (3) ◽  
pp. 319-324 ◽  
Author(s):  
Sven Rockitt ◽  
Rudolf Wartchow ◽  
Helmut Duddeck ◽  
Anna Drabczynska ◽  
Katarzyna Kiec-Kononowicz
Keyword(s):  
Solid State ◽  
Diffraction Analysis ◽  
Carbonyl Group ◽  
Enantiomeric Excess ◽  
Carbonyl Groups ◽  
X Ray Diffraction ◽  
Nmr Studies ◽  
X Ray ◽  
C Nmr

Abstract It is show n by IR and NMR studies that the xanthines 1-5 prefer a side-on com plexation to the chiral dirhodium tetrakis[(R)-α-methoxy-α-(trifluoromethyl)phenylacetatel (Rh*) in solution whereas carbonyl groups are involved in the solid state. For 6, at least the carbonyl group C-6 contributes to complexation in solution as well. A lternating strands of 6 and Rh* exist in the solid state as revealed by X-ray diffraction analysis described in detail. The determination of enantiomeric excess of the chiral xanthine 6 can easily be accomplished by the “dirhodium method ” (1H and 13C NMR in the presence of Rh*).

Phosphine chalcogenide complexes of antimony(III) halides

2015 ◽  
Vol 93 (3) ◽  
pp. 375-379 ◽  
Author(s):  
Karlee L. Bamford ◽  
Alasdair P.M. Robertson ◽  
Hilary A. Jenkins ◽  
Brian O. Patrick ◽  
Neil Burford
Keyword(s):  
Solid State ◽  
Single Crystal ◽  
Phosphine Oxide ◽  
State Structure ◽  
X Ray Diffraction ◽  
Solid State Structure ◽  
X Ray ◽  
Derivatives Of

Three series of phosphine chalcogenide complexes of the antimony(III) halides SbX3 (X = F, Cl, Br, or I) have been synthesized and characterized by spectroscopic and crystallographic methods. Complexes of the generic formulae (Cy3PO)SbX3 (X = F (1a), Cl (1b), or Br (1c)), (Cy3PO)2SbX3 (X = F (2a), Cl (2b), or Br (2c)), and (Cy3PS)SbX3 (X = Cl (3b), Br (3c), or I (3d)) were synthesized via the treatment of solutions of SbX3 with OPCy3 and SPCy3, respectively. Derivatives of (Cy3PO)SbX3 were characterized by single crystal X-ray diffraction for 1a and 1b and crystallize as dimers through symmetry related intermolecular Sb–X interactions, providing the first structurally characterized examples of this class of complex. Derivatives of (Cy3PS)SbX3 (3b–3c) adopt analogous dimeric structures in the solid state. The solid-state structure of (Cy3PO)2SbCl3 (2b) is consistent with the previously reported structures of bis-phosphine oxide complexes of antimony(III), with a square pyramidal Sb center and cis-configured OPCy3 ligands. The phosphine chalcogenide complexes of SbX3 display configurations that are consistent with the perceived trans-labilizing properties of the ligands/substituents.

scholarly journals Studies of Dihydropyridines by X-Ray Diffraction and Solid State 13C NMR

2007 ◽  
Vol 62 (4) ◽  
pp. 549-555 ◽  
Author(s):  
Martha S. Morales-Ríos ◽  
Antonio Martínez-Richa ◽  
Zurisaddai Hernández-Gallegos ◽  
Angelina Hernández-Barragán ◽  
Ricardo Vera-Graziano ◽  
...  
Keyword(s):  
Solid State ◽  
Phenyl Ring ◽  
Chemical Shifts ◽  
Carbonyl Groups ◽  
X Ray Diffraction ◽  
Substitution Pattern ◽  
Trans Orientation ◽  
X Ray ◽  
Nmr Data ◽  
C Nmr

Fourteen dimethyl 4-aryl-2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylates (DHPs) were evaluated by means of single crystal X-ray diffraction in order to investigate the effects of the structure in the crystals on the solid state 13C NMR chemical shifts. These include the analysis of three DHPs containing two molecules per asymmetric unit. The chiral rotamer unit generated by the s-cis/s-trans orientation of the carbonyl groups, as well as by rotation of the 4-phenyl ring out of the bisecting plane containing the N1, C4, C7 atoms, resulted in a significant magnetic non-equivalence for the C2-CH3/C6-CH3 and the COOCH3 pairs of signals. The solid state 13C NMR data reveal that the substitution pattern of the phenyl ring has a marked effect on the extent to which the signals of the carbonyl carbon atoms and those of C-2/C-6 peaks are split.

Mono- and Di-Lanthanide Derivatives of 19-Tungsto-2-Arsenate(III)

2010 ◽  
Vol 65 (3) ◽  
pp. 383-r392 ◽  
Author(s):  
Amal H Ismail ◽  
Bassem S Bassil ◽  
Isabella Römer ◽  
Nils C. Redeker ◽  
Ulrich Kortz
Keyword(s):  
Solid State ◽  
Ftir Spectroscopy ◽  
Potassium Salt ◽  
Aqueous Media ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lanthanum Ions ◽  
Triclinic System ◽  
Cell Dimensions ◽  
Derivatives Of

Two types of lanthanide-containing derivatives of the 19-tungsto-2-arsenate(III) [As2W19O67- (H2O)]14− (As2W19) have been synthesized in mildly acidic aqueous media and characterized in the solid state. The ytterbium(III)-containing anion [Yb(H2O)2K(H2O)2As2W19O67(H2O)]10− (1) was formed by reaction of Yb3+ with the potassium salt of As2W19, while the lanthanum(III) derivative [La2(H2O)6As2W19O67(H2O)]8− (2) was formed by reaction of La3+ with the sodium salt of the trilacunary precursor [B-α-AsW9O33]9− (AsW9). The polyanions 1 and 2 crystallize as hydrated salts in the triclinic system, space group P1̄: K9.5Na0.5[Yb(H2O)2K(H2O)2As2W19O67(H2O)]·25H2O (KNa-1) with cell dimensions a = 12.4730(5), b = 17.4630(9), c = 21.1990(10) Å, α = 72.568(3)◦, β = 85.442(2)◦, γ = 89.147(3)◦, Z = 2; Na8[La2(H2O)8As2W19O67(H2O)]·17H2O (Na-2) with cell dimensions a = 14.929(2), b = 17.769(3), c = 20.754(4) Å, α = 77.203(10)◦, β = 80.273(9)◦, γ = 72.670(9)◦, Z = 2. Both compounds KNa-1 and Na-2 were characterized in the solid state by FTIR spectroscopy, TGA and single-crystal X-ray diffraction analyses. In polyanion 1, the As2W19 unit sandwiches one ytterbium and one potassium ion leading to a structure with idealized Cs symmetry, whereas polyanion 2 incorporates two lanthanum ions leading to a structure with idealized C2v symmetry. Compositional analogs of polyanions 1 (Ln = La, Ce, Eu, Gd and Lu) and 2 (Ce) were also synthesized and identified by FTIR spectroscopy.

scholarly journals New Members of the Cinchona Alkaloids Family: Assembly of the Triazole Heterocycle at the 6′ Position

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3357
Author(s):  
Catalin Vasile Maftei ◽  
Martin Heiko Franz ◽  
Christian Kleeberg ◽  
Ion Neda
Keyword(s):  
Solid State ◽  
Ring System ◽  
Cinchona Alkaloids ◽  
X Ray Diffraction ◽  
New Members ◽  
X Ray ◽  
Direct Pathway ◽  
Primary Amino ◽  
Solid State Structures ◽  
Derivatives Of

The substance class of the well-known Cinchona alkaloids is widened by 6′-Amino-cinchonine and 6′-Amino-cinchonidine, novel compounds which incorporate a primary amino function in the quinolinic ring system. These key intermediates open the field for a range of fruitful chemistry. Here is described a short and direct pathway for the synthesis of triazole containing derivatives of the above-mentioned substances using the [3 + 2] Huisgen cycloaddition. For this purpose, the amines were first converted into the corresponding azides. Based on this, non-substituted and silyl-protected triazoles were synthesized as examples. Furthermore, didehydrated derivatives of quincorine and quincoridine were used as addition partners, resulting in compounds that carry the quinuclidine ring of the cinchona alkaloids at both ends. Some of these compounds were examined radiographically to investigate the position of the quinuclidine ring to the triazole. The solid-state structures of compounds 10, 11 and 28 were determined by X-ray diffraction analyses.

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