scholarly journals Friedel–Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates. Efficient synthesis of highly fluorescent diethyl 1-(pyrene-1-carboxamido)alkylphosphonates and 1-(pyrene-1-carboxamido)methylphosphonic acid

2015 ◽  
Vol 11 ◽  
pp. 2451-2458 ◽  
Author(s):  
Anna Wrona-Piotrowicz ◽  
Janusz Zakrzewski ◽  
Anna Gajda ◽  
Tadeusz Gajda ◽  
Anna Makal ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Fluorescence Quantum Yield ◽  
Fold Increase ◽  
Methylphosphonic Acid ◽  
Efficient Synthesis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Type Reaction ◽  
Intramolecular Hydrogen

Friedel–Crafts-type reaction of pyrene with diethyl 1-(isothiocyanato)alkylphosphonates promoted by trifluoromethanosulfonic acid afforded diethyl 1-(pyrene-1-carbothioamido)alkylphosphonates in 83–94% yield. These compounds were transformed, in 87–94% yield, into the corresponding diethyl 1-(pyrene-1-carboxamido)alkylphosphonates by treatment with Oxone®. 1-(Pyrene-1-carboxamido)methylphosphonic acid was obtained in a 87% yield by treating the corresponding diethyl phosphonate with Me3Si-Br in methanol. All of the synthesized amidophosphonates were emissive in solution and in the solid state. The presence of a phosphonato group brought about an approximately two-fold increase in solution fluorescence quantum yield in comparison with that of a model N-alkyl pyrene-1-carboxamide. This effect was tentatively explained by stiffening of the amidophosphonate lateral chain which was caused by the interaction (intramolecular hydrogen bond) of phosphonate and amide groups. The synthesized phosphonic acid was soluble in a biological aqueous buffer (PBS, 0.01 M, pH 7.35) and was strongly emissive under these conditions (λem = 383, 400 nm, τ = 18.7 ns, ΦF > 0.98). Solid-state emission of diethyl 1-(pyrene-1-carboxamido)methylphosphonate (λmax = 485 nm; ΦF = 0.25) was assigned to π–π aggregates, the presence of which was revealed by single-crystal X-ray diffraction analysis.

scholarly journals Synthesis and Complexation Properties of 2-Hydroxy-5-methoxyphenylphosphonic Acid (H3L1). Crystal Structure of the [Cu(H2L1)2(Н2О)2] Complex

2021 ◽  
Vol 91 (11) ◽  
pp. 2176-2186
Author(s):  
G. S. Tsebrikova ◽  
Yu. I. Rogacheva ◽  
I. S. Ivanova ◽  
A. B. Ilyukhin ◽  
V. P. Soloviev ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Methoxy Group ◽  
Protonation Constants ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Stability ◽  
Intramolecular Hydrogen ◽  
Oxygen Atoms

Abstract 2-Hydroxy-5-methoxyphenylphosphonic acid (H3L1) and the complex [Cu(H2L1)2(H2O)2] were synthesized and characterized by IR spectroscopy, thermogravimetry, and X-ray diffraction analysis. The polyhedron of the copper atom is an axially elongated square bipyramid with oxygen atoms of phenolic and of monodeprotonated phosphonic groups at the base and oxygen atoms of water molecules at the vertices. The protonation constants of the H3L1 acid and the stability constants of its Cu2+ complexes in water were determined by potentiometric titration. The protonation constants of the acid in water are significantly influenced by the intramolecular hydrogen bond and the methoxy group. The H3L1 acid forms complexes CuL‒ and CuL24‒ with Cu2+ in water.

Single Crystal Formation by Solid-State Reaction Between p-Benzoquinone and 2,4,5-Trichlorophenol

2002 ◽  
Vol 55 (4) ◽  
pp. 271 ◽  
Author(s):  
N. B. Singh ◽  
A. Pathak ◽  
R. Fröhlich
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Single Crystal ◽  
Single Crystals ◽  
Solid State Reaction ◽  
Carbonyl Oxygen ◽  
Crystal Formation ◽  
X Ray Diffraction ◽  
X Ray

Vapours of p-benzoquinone (BQ) have been found to react with solid 2,4,5-trichlorophenol (TCP). The reaction product (BQ-TCP) separated in the form of monoclinic single crystals, the structure of which was determined by X-ray diffraction to reveal that the two molecules are linked by a single hydrogen bond between the carbonyl oxygen of BQ and the phenolic hydrogen of TCP.

A Solid-State NMR, X-ray Diffraction, and ab Initio Computational Study of Hydrogen-Bond Structure and Dynamics of Pyrazole-4-Carboxylic Acid Chains

2001 ◽  
Vol 123 (32) ◽  
pp. 7898-7906 ◽  
Author(s):  
Concepción Foces-Foces ◽  
Aurea Echevarría ◽  
Nadine Jagerovic ◽  
Ibon Alkorta ◽  
José Elguero ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Carboxylic Acid ◽  
Ab Initio ◽  
Solid State Nmr ◽  
Computational Study ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structure And Dynamics

Structural characterization of p-benzosemiquinone radical in a solid state: the radical stabilization by a low-barrier hydrogen bond

2006 ◽  
Vol 62 (6) ◽  
pp. 1051-1060 ◽  
Author(s):  
Krešimir Molčanov ◽  
Biserka Kojić-Prodić ◽  
Mario Roboz
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Variable Temperature ◽  
Organic Radical ◽  
X Ray Diffraction ◽  
X Ray ◽  
Crystal Packings ◽  
Dynamical Disorder ◽  
Benzenoid Ring

Semiquinone (p-benzosemiquinone), a transient organic radical, was detected in the solid state by EPR spectroscopy revealing four symmetrically equivalent protons. A variable-temperature X-ray diffraction analysis (293 and 90 K) and EPR data support a dynamical disorder of the proton. A low-barrier O—H···O hydrogen bond stabilizes the radical. The C—O bond length is 1.297 (4) Å, corresponding to a bond order of ca 1.5. The geometry of the radical implies an electron delocalization throughout the benzenoid ring. Two polymorphs of semiquinone, monoclinic and triclinic, were observed and their structures determined. Their crystal packings were compared with those of quinhydrone polymorphs.

The synthesis of 5-hydroxy chromenes

1985 ◽  
Vol 63 (10) ◽  
pp. 2589-2596 ◽  
Author(s):  
J. W. ApSimon ◽  
L. W. Herman ◽  
C. Huber
Keyword(s):  
Hydrogen Bond ◽  
Oxygen Atom ◽  
Intramolecular Hydrogen Bond ◽  
Hydroxyl Group ◽  
X Ray ◽  
Type Reaction ◽  
Intramolecular Hydrogen ◽  
Strong Intramolecular Hydrogen Bond

The synthesis of 2,2-dimethyl-5-hydroxychromene (1d) is described. The synthesis of the analogous 5,7-dihydroxy derivatives, using similar conditions, yields the adduct 9 derived via a Bucherer type reaction. X-ray analysis of 9 demonstrated that a pyrrolidine group was in the 7-position, and that the 5-hydroxyl group was involved in a strong intramolecular hydrogen bond to the 4-keto oxygen atom.

Structure and hydrogen bonding in 2,4-dihydroxybenzoic acid at 90, 100, 110 and 150 K; a theoretical and single-crystal X-ray diffraction study

2007 ◽  
Vol 63 (2) ◽  
pp. 303-308 ◽  
Author(s):  
Andrew Parkin ◽  
Martin Adam ◽  
Richard I. Cooper ◽  
Derek S. Middlemiss ◽  
Chick C. Wilson
Keyword(s):  
Hydrogen Bonding ◽  
Solid State ◽  
Hydrogen Bonds ◽  
X Ray Diffraction ◽  
Dihydroxybenzoic Acid ◽  
X Ray ◽  
Hydrogen Bond System ◽  
Proton Disorder ◽  
Intramolecular Hydrogen ◽  
Carboxylic Acid Dimer

A new polymorph of 2,4-dihydroxybenzoic acid is reported. The structure was characterized by multiple-temperature X-ray diffraction and solid-state DFT computations. The material shows a geometric pattern of hydrogen bonding consistent with cooperativity between the intermolecular carboxylic acid dimer and intramolecular hydrogen bonds. The presence of proton disorder within this hydrogen-bond system, which would support such a cooperative model, was not fully ruled out by the initial X-ray studies. However, solid-state calculations on the three possible end-point tautomers indicate that the dominant crystallographically observed configuration is substantially lower in energy than the other tautomers (by at least 9 kJ mol−1), indicating that no disorder should be expected. It is therefore concluded that no disorder is observed either in the intra- or intermolecular hydrogen bonds of the title compound and that the cooperativity between the hydrogen bonds is not present within the temperature range studied.

A Study of Diastereomeric Mandelate Salts of Cinchonidine and the Relation to Their Quasidiastereomeric Analogues

1997 ◽  
Vol 53 (4) ◽  
pp. 708-718 ◽  
Author(s):  
A. Gjerløv ◽  
S. Larsen
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Mandelic Acid ◽  
Crystal Packing ◽  
Steric Effects ◽  
Quinoline Ring ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diastereomeric Salts ◽  
Vinyl Group

The crystal structures have been determined for the diastereomeric salts formed by cinchonidine and the two enantiomers of mandelic acid using low-temperature [122 (1) K] X-ray diffraction data. The less soluble salt is cinchonidinium (S)-mandelate, C19H23N20O+.C8H7O3 −, M r = 446.53, monoclinic, C2, a = 21.400 (2), b = 6.2777 (6), c = 17.853 (2) Å3, \beta = 109.304 (8)°, V = 2263.6 (4) Å3, Z = 4, D x = 1.310 g cm−3, \lambda(Cu K\alpha = 1.54184 Å, Z = 7.08 cm−1, F(000) = 952, R 1 = 0.0259 for 2684 observed reflections. The cinchonidine salt with (R)-mandelic acid, C19H23N2O+.C8H7O3, has M r = 446.53, monoclinic, P21, a = 6.410 (3), b = 32.808 (11), c = 11.222 (2) Å, \beta = 100.67 (2)°, V = 2319.2 (13) Å3, Z = 4, D x = 1.279 g cm−3, \lambda(Cu K\alpha) = 1.54184 Å, \mu = 6.91 cm−1, F(000) = 952, R 1 = 0.0380 for 8951 observed reflections. The two salts have virtually identical hydrogen-bond patterns and similar herringbone stacking of the quinoline ring systems. The crystal packing of the two salts differ only with respect to the packing of the phenyl groups. The packing of the cinchonidinium mandelates is significantly different from the crystal packing in the corresponding mandelates of cinchonine. The lack of a quasidiastereomeric relationship between the two sets of salts can be attributed to the steric effects of the vinyl group. The similarities between the two cinchonidinium mandelate structures is a possible explanation to the similar solubilities of the salts. DSC and NMR measurements showed that the cinchonidinium salts undergo a chemical opening reaction in the solid state. The arrangement of hydrogen-bonded chains of alternating cations and anions appear to be important for the solid-state reaction to take place.

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).

A Solid-State Dehydration Process in an Organic Material Associated with Substantial Hydrogen-Bond Reorganization, Investigated by Powder X-ray Diffraction

2010 ◽  
Vol 10 (7) ◽  
pp. 3176-3181 ◽  
Author(s):  
Javier Martí-Rujas ◽  
Anabel Morte-Ródenas ◽  
Fang Guo ◽  
Nigel Thomas ◽  
Kotaro Fujii ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Solid State ◽  
Organic Material ◽  
Dehydration Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Bond Reorganization
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