PCILO study of hydrogen bond and proton transfer in systems 1-methylthymine-acetamide and 1-methylthymine-acetic acid

1981 ◽  
Vol 46 (4) ◽  
pp. 957-962 ◽  
Author(s):  
Milan Remko
Keyword(s):  
Hydrogen Bond ◽  
Acetic Acid ◽  
Hydrogen Bonds ◽  
Proton Transfer ◽  
Quantum Chemical ◽  
Potential Functions ◽  
Double Proton Transfer ◽  
Proton Potential ◽  
Pcilo Method

Complexes containing two hydrogen bonds of the systems 1-methylthymine-acetamide and 1-methylthymine-acetic acid have been studied by the quantum-chemical PCILO method. In accordance with experiment our PCILO calculations have shown that acetic acid forms stronger hydrogen bonds than acetamide with 1-methylthymine. Further the PCILO method has been used to study of double proton transfer in O-H...O and N-H...O bonds of the complexes 1-methylthymine-acetamide and 1-methylthymine-acetic acid. Using equilibrium O...O and N...O distances, the PCILO calculations have given one-minimum proton potential functions. The proton transfer has not been observed. At somewhat longer N...O and O...O distances (0.30 nm) the PCILO calculations indicate a second minimum as a shoulder.

Hydrogen bonds and proton transfer in imidazole oligomers and (imidazole)2H(+) system: quantum-chemical calculations

1980 ◽  
Vol 45 (12) ◽  
pp. 3482-3487 ◽  
Author(s):  
Milan Remko
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Proton Transfer ◽  
Quantum Chemical ◽  
Equilibrium Distance ◽  
Hydrogen Bond Energy ◽  
Proton Potential ◽  
Pcilo Method ◽  
System Quantum ◽  
Semi Empirical

The semi-empirical PCILO method has been applied to study of hydrogen bonds and proton transfer in linear n-mers of imidazole (n = 3). The calculated hydrogen bond energy in the dimer is 30.64 kJ mol-1. In imidazole trimer interaction energy of the "second" hydrogen bond increased to 32.02 kJ mol-1. One-minimum functions only have been found by calculations of the proton potential functions in imidazole dimer and trimer for the equilibrium distances RN...N. For somewhat longer distances RN...N = 0.30 nm a second minimum was observed as shoulder. On the contrary, for the (imidazole)2H(+) system the proton potential curve has two minima for the equilibrium distance RN...N = 0.252 nm, the second minimum is more stable by 3.97 kJ mol-1.

Quantum-chemical study of energy surface and the minimum-energy reaction path of the proton transfer along O-H...N hydrogen bond in acetic acid-imidazole x 2 H2O system

1982 ◽  
Vol 47 (7) ◽  
pp. 1893-1896 ◽  
Author(s):  
Milan Remko
Keyword(s):  
Hydrogen Bond ◽  
Acetic Acid ◽  
Proton Transfer ◽  
Quantum Chemical ◽  
Energy Surface ◽  
Reaction Path ◽  
Minimum Energy ◽  
Quantum Chemical Study ◽  
Energy Minimum ◽  
Energy Reaction

The semi-empirical quantum-chemical PCILO method has been used for calculation of the energy surface of the proton transfer along the O-H...N hydrogen bond in acetic acid-imidazole . 2 H2O system. The PCILO calculations gave the energy surface with two minima. The most stable minimum corresponds to the O-H...N hydrogen bond and has been found at the distances RH...N = 0.149 nm and RO...N = 0.107 nm. According to the PCILO calculations the proton transfer is accompanied by significant changes in the O...N distance. The second energy minimum corresponding to the proton transfer O-...NH+ complex has been found at RH...N = 0.10 nm and RO...N = 0.30 nm. The approximative minimum energy reaction path for the proton transfer has been calculated by the procedure developed by Muller and Brown. The calculated energy barrier represents a value 376.15 kJ/mol. The second energy minimum lies higher by 246 kJ/mol.

Quantum-chemical study of N-methylacetamide and N,N-dimethylacetamide as models for peptidic bond in hydrogen-bond interaction with water, methanol and phenol

1983 ◽  
Vol 48 (11) ◽  
pp. 3214-3222 ◽  
Author(s):  
Milan Remko ◽  
Ivan Sekerka ◽  
Vladimír Frecer
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Quantum Chemical ◽  
Quantum Chemical Study ◽  
Geometry Optimization ◽  
Chemical Study ◽  
Hydrogen Bond Interaction ◽  
Proton Donors ◽  
Pcilo Method ◽  
Peptide Hydrogen

The PCILO quantum-chemical method with geometry optimization has been used to study rotation barriers of methyl groups in N-methylacetamide and N,N-dimethylacetamide. In all the cases studied, the eclipsed conformation have been found to be the most stable. Cis form of N-methylacetamide is less stable than the corresponding trans form by 2.0 kJ mol-1. Moreover, the PCILO method has been used to study linear n-mers (n = 4) of N-methylacetamide. On going from the dimer to tri- and tetramers, the hydrogen-bond energies have been found non-additive, and positive cooperativity has been observed. Finally, hydrogen-bond complexes have been studied which were formed by C=O groups of N-methylacetamide and N,N-dimethylacetamide with water, methanol or phenol as proton-donors. The said proton-donors have been found to act as breakers of inter-peptide hydrogen bonds N-H...O=C. The hydrogen bonds formed by methanol are somewhat stronger than those formed by water. In accordance with experiment, the strongest hydrogen bonds with the studied proton-acceptors are formed by phenol.

scholarly journals Crystal structure and hydrogen bonding in the water-stabilized proton-transfer salt brucinium 4-aminophenylarsonate tetrahydrate

2016 ◽  
Vol 72 (5) ◽  
pp. 751-755 ◽  
Author(s):  
Graham Smith ◽  
Urs D. Wermuth
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bond ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Proton Transfer ◽  
Network Structure ◽  
Three Dimensional ◽  
Water Molecules ◽  
Arsanilic Acid ◽  
Dimensional Network

In the structure of the brucinium salt of 4-aminophenylarsonic acid (p-arsanilic acid), systematically 2,3-dimethoxy-10-oxostrychnidinium 4-aminophenylarsonate tetrahydrate, (C23H27N2O4)[As(C6H7N)O2(OH)]·4H2O, the brucinium cations form the characteristic undulating and overlapping head-to-tail layered brucine substructures packed along [010]. The arsanilate anions and the water molecules of solvation are accommodated between the layers and are linked to them through a primary cation N—H...O(anion) hydrogen bond, as well as through water O—H...O hydrogen bonds to brucinium and arsanilate ions as well as bridging water O-atom acceptors, giving an overall three-dimensional network structure.

scholarly journals A new solvate of epalerstat, a drug for diabetic neuropathy

2017 ◽  
Vol 73 (8) ◽  
pp. 1264-1267 ◽  
Author(s):  
Okky Dwichandra Putra ◽  
Daiki Umeda ◽  
Kaori Fukuzawa ◽  
Mihoko Gunji ◽  
Etsuo Yonemochi
Keyword(s):  
Hydrogen Bond ◽  
Acetic Acid ◽  
Carboxylic Acid ◽  
Hydrogen Bonds ◽  
Diabetic Neuropathy ◽  
Dihedral Angle ◽  
Phenyl Ring ◽  
Acid Moiety ◽  
Acta Cryst ◽  
Carboxylic Acid Groups

Epalerstat {systematic name: (5Z)-5-[(2E)-2-methyl-3-phenylprop-2-en-1-ylidene]-4-oxo-2-sulfanylidene-1,3-thiazolidine-3-acetic acid} crystallized as an acetone monosolvate, C15H13NO3S2·C3H6O. In the epalerstat molecule, the methylpropylenediene moiety is inclined to the phenyl ring and the five-membered rhodamine ring by 21.4 (4) and 4.7 (4)°, respectively. In addition, the acetic acid moiety is found to be almost normal to the rhodamine ring, making a dihedral angle of 85.1 (2)°. In the crystal, a pair of O—H...O hydrogen bonds between the carboxylic acid groups of epalerstat molecules form inversion dimers with an R 2 2(8) loop. The dimers are linked by pairs of C—H...O hydrogen bonds, enclosing R 2 2(20) loops, forming chains propagating along the [101] direction. In addition, the acetone molecules are linked to the chain by a C—H...O hydrogen bond. Epalerstat acetone monosolvate was found to be isotypic with epalerstat tertrahydrofuran solvate [Umeda et al. (2017). Acta Cryst. E73, 941–944].

Ground and Excited-State Acetic Acid Catalyzed Double Proton Transfer in 2-Aminopyridine†

2003 ◽  
Vol 107 (18) ◽  
pp. 3244-3253 ◽  
Author(s):  
Fa-Tsai Hung ◽  
Wei-Ping Hu ◽  
Tsung-Hui Li ◽  
Chung-Chih Cheng ◽  
Pi-Tai Chou
Keyword(s):  
Acetic Acid ◽  
Excited State ◽  
Proton Transfer ◽  
Double Proton Transfer ◽  
Acid Catalyzed

Polysulfonylamine, CLXXXIX [1]. Weitere Beispiele für die O-Protonierung von Harnstoffen mit Di(organosulfonyl)aminen: Bildung und Kristallstrukturen von 1,1-Dimethyluroniumdi( 4-fluorbenzolsulfonyl)amid und Di(1-methylharnstoff)- hydrogen(I)-di(4-fluorbenzolsulfonyl)amid/ Polysulfonylamines, CLXXXIX. Additional Examples of the O-Protonation of Ureas by Di(organosulfonyl)amines: Formation and Crystal Structures of 1,1-Dimethyluronium Di(4-fluorobenzenesulfonyl)amide and Di(1-methylurea)hydrogen(I)Di(4-fluorobenzenesulfonyl) amide

2010 ◽  
Vol 65 (11) ◽  
pp. 1363-1371 ◽  
Author(s):  
Christoph Wölper ◽  
Alejandra Rodríguez-Gimeno ◽  
Katherine Chulvi Iborra ◽  
Peter G. Jones ◽  
Armand Blaschette
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Proton Transfer ◽  
Petroleum Ether ◽  
Crystal Structures ◽  
Monoclinic Space Group ◽  
One Dimensional ◽  
Bond Lengths ◽  
Ionic Compounds ◽  
Specific Elongation

Co-crystallization of N-methyl-substituted ureas with di(organosulfonyl)amines, (RSO2)2NH, leads unpredictably to either molecular co-crystals or, via proton transfer, to uronium salts. As a sequel to former reports, this communication describes the formation and the crystal structures of the new ionic compounds 1,1-dimethyluronium di(4-fluorobenzenesulfonyl)amide (1, monoclinic, space group P21/c, Z´ = 1) and di(1-methylurea)hydrogen(I) di(4-fluorobenzenesulfonyl)amide (2, triclinic, P1̄, Z´ = 1); both salts were obtained from dichloromethane/petroleum ether. In the structure of 2, the urea moieties of the cationic homoconjugate are connected by a very short [O-H· · ·O]+ hydrogen bond [d(O· · ·O) = 244.6(2) pm, θ (O-H· · ·O)≈170°, bridging H atom asymmetrically disordered over two positions]. The O-protonation induces a specific elongation of the C-O bond lengths to 131.2(2) pm in 1 or 129.5(2) and 127.4(2) pm in 2, as compared to literature data of ca. 126 pm for the unprotonated ureas. Both crystal structures are dominated by conventional two- and threecentre hydrogen bonds, which involve the OH and all NH donors and give rise to one-dimensional cation-anion arrays. In particular, the ionic entities of 1 are alternatingly associated into simple chains propagated by glide-plane operations parallel to the c axis, whereas the donor-richer structure of 2 displays inversion symmetric dimers of formula units, which are further hydrogen-bonded into strands propagated by translation parallel to the a axis.

Mechanism of Excited State Double Proton Transfer in 2-Amino-3-Methoxypyridine and Acetic Acid Complex

2018 ◽  
Vol 35 (9) ◽  
pp. 098201 ◽  
Author(s):  
Qing-Chi Meng ◽  
Song-Qiu Yang ◽  
Guang-Hua Ren ◽  
Tian-Shu Chu
Keyword(s):  
Acetic Acid ◽  
Excited State ◽  
Proton Transfer ◽  
Acid Complex ◽  
Double Proton Transfer

Isotope effects associated with tunneling and double proton transfer in the hydrogen bonds of benzoic acid

2004 ◽  
Vol 120 (23) ◽  
pp. 11107-11119 ◽  
Author(s):  
Q. Xue ◽  
A. J. Horsewill ◽  
M. R. Johnson ◽  
H. P. Trommsdorff
Keyword(s):  
Hydrogen Bonds ◽  
Benzoic Acid ◽  
Proton Transfer ◽  
Isotope Effects ◽  
Double Proton Transfer

Double proton transfer in the complex of acetic acid with methanol: Theory versus experiment

2001 ◽  
Vol 114 (4) ◽  
pp. 1567-1574 ◽  
Author(s):  
Antonio Fernández-Ramos ◽  
Zorka Smedarchina ◽  
Jesús Rodrı́guez-Otero
Keyword(s):  
Acetic Acid ◽  
Proton Transfer ◽  
Double Proton Transfer ◽  
Theory Versus
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