Revisiting the role of acids and hydrogen bond acceptors in enamine formation

2020 ◽  
Vol 18 (35) ◽  
pp. 6849-6852
Author(s):  
Zhichao Lu ◽  
Gerald B. Hammond ◽  
Bo Xu
Keyword(s):  
Hydrogen Bond ◽  
Reaction Rates ◽  
Systematic Investigation ◽  
Enamine Formation

A systematic investigation into the effects of acids and hydrogen bond acceptors on the reaction rates and equilibria of enamine formation is reported.

Role of strong intramolecular N—H...N hydrogen bonds in determining the conformation of adenosine-receptor antagonists

2006 ◽  
Vol 62 (4) ◽  
pp. 634-641 ◽  
Author(s):  
Valeria Ferretti ◽  
Loretta Pretto ◽  
Mojgan Aghazadeh Tabrizi ◽  
Paola Gilli
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Adenosine Receptors ◽  
Systematic Investigation ◽  
New Drugs ◽  
Receptor Subtypes ◽  
Pyrimidine Derivatives ◽  
Planar Conformation ◽  
Chemical Class

Over the last few years many efforts have been devoted to the discovery of new adenosine antagonists which can selectively bind to one of the four adenosine receptors, called A1, A2A, A2B and A3, in order to develop new drugs with few side effects. The present paper reports the crystal structures of four newly synthesized antagonists belonging to the chemical class of pyrazolo-triazolo-pyrimidine derivatives, which display good affinity and selectivity properties towards the A2A or A3 receptor subtypes. These molecules assume an overall planar conformation due to the formation of strong intramolecular N—H...N hydrogen bonds. A systematic investigation on molecules containing the ureidic —NH—C(=O,S)—NH—C=N— fragment has shown that the formation of such interactions is a common feature for this class of compounds. The associated energy, evaluated through DFT calculations, is some 50.24 kJ mol−1, leading to the conclusion that the hydrogen bond, and consequently the planar conformation, is retained not only in the solid state but also in solution during the interaction of the molecule with its receptor.

Have Duchenne Muscular Dystrophy Patients an Increased Cancer Risk?

2021 ◽  
pp. 1-5
Author(s):  
Gian Luca Vita ◽  
Luisa Politano ◽  
Angela Berardinelli ◽  
Giuseppe Vita
Keyword(s):  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Systematic Investigation ◽  
Mdx Mice ◽  
True Incidence ◽  
Patients With Cancer ◽  
Dmd Gene ◽  
Age Range ◽  
Prevalence Of Cancer

Background: Increasing evidence suggests that Duchenne muscular dystrophy (DMD) gene is involved in the occurrence of different types of cancer. Moreover, development of sarcomas was reported in mdx mice, the murine model of DMD, in older age. So far, nine isolated DMD patients were reported with concomitant cancer, four of whom with rhabdomyosarcoma (RMS), but no systematic investigation was performed about the true incidence of cancer in DMD. Methods: All members of the Italian Association of Myology were asked about the occurrence of cancer in their DMD patients in the last 30 years. Results: Four DMD patients with cancer were reported after checking 2455 medical records. One developed brain tumour at the age of 35 years. Two patients had alveolar RMS at 14 and 17 years of age. The fourth patient had a benign enchondroma when 11-year-old. Conclusion: Prevalence of cancer in general in the Italian DMD patients does not seem to be different from that in the general population with the same age range. Although the small numbers herein presented do not allow definitive conclusion, the frequent occurrence of RMS in DMD patients raises an alert for basic researchers and clinicians. The role of DMD gene in cancer merits further investigations.

Role of the hydrogen bond donor component for a proper development of novel hydrophobic deep eutectic solvents

2019 ◽  
Vol 281 ◽  
pp. 423-430 ◽  
Author(s):  
Matteo Tiecco ◽  
Federico Cappellini ◽  
Francesco Nicoletti ◽  
Tiziana Del Giacco ◽  
Raimondo Germani ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Deep Eutectic Solvents ◽  
Hydrogen Bond Donor

scholarly journals On the role of hydrogen-bond exchanges in the spectral diffusion of water

2021 ◽  
Vol 154 (6) ◽  
pp. 064501
Author(s):  
Zeke A. Piskulich ◽  
Damien Laage ◽  
Ward H. Thompson
Keyword(s):  
Hydrogen Bond ◽  
Spectral Diffusion

On the potential role of the amino nitrogen atom as a hydrogen bond acceptor in macromolecules

1998 ◽  
Vol 279 (5) ◽  
pp. 1123-1136 ◽  
Author(s):  
Ben Luisi ◽  
Modesto Orozco ◽  
Jiri Sponer ◽  
Francisco J Luque ◽  
Zippora Shakked
Keyword(s):  
Hydrogen Bond ◽  
Nitrogen Atom ◽  
Potential Role ◽  
Amino Nitrogen ◽  
Hydrogen Bond Acceptor ◽  
Amino Nitrogen Atom

Molecular Dynamics Simulations for Loading-Dependent Diffusion of CO2, SO2, CH4, and Their Binary Mixtures in ZIF-10: The Role of Hydrogen Bond

Langmuir ◽  
2017 ◽  
Vol 33 (42) ◽  
pp. 11543-11553 ◽  
Author(s):  
Li Li ◽  
Deshuai Yang ◽  
Trevor R. Fisher ◽  
Qi Qiao ◽  
Zhen Yang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Hydrogen Bond ◽  
Molecular Dynamics Simulations ◽  
Binary Mixtures ◽  
Dynamics Simulations

Insight into structure, stability and hydrogen bond in complexes of guanine and thymine at the molecular level using computational chemical method

2021 ◽  
Vol 11 (1) ◽  
pp. 127-134
Author(s):  
Nhung Ngo Thi Hong ◽  
Huong Dau Thi Thu ◽  
Trung Nguyen Tien
Keyword(s):  
Hydrogen Bond ◽  
Hydrogen Bonds ◽  
Energy Surface ◽  
Covalent Bond ◽  
Electrostatic Energy ◽  
Substantial Contribution ◽  
Structure Stability ◽  
Dispersion Terms ◽  
Insight Into

Nine stable structures of complexes formed by interaction of guanine with thymine were located on potential energy surface at B3LYP/6-311++G(2d,2p). The complexes are quite stable with interaction energy from -5,8 to -17,7 kcal.mol-1. Strength of complexes are contributed by hydrogen bonds, in which a pivotal role of N−H×××O/N overcoming C−H×××O/N hydrogen bond, up to to 3.5 times, determines stabilization of complexes investigated. It is found that polarity of N/C−H covalent bond over proton affinity of N/O site governs stability of hydrogen bond in the complexes. The obtained results show that the N/C−H×××O/N red-shifting hydrogen bonds occur in all complexes, and a larger magnitude of an elongation of N−H compared C-H bond length accompanied by a decrease of its stretching frequency is detected in the N/C−H×××O/N hydrogen bond upon complexation. The SAPT2+ analysis indicates the substantial contribution of attractive electrostatic energy versus the induction and dispersion terms in stabilizing the complexes.

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