Intramolecular Hydrogen-Bond Interactions Tune Reactivity in Biomimetic Bis(μ-hydroxo)dicobalt Complexes

Author(s):  
Alyssa A. DeLucia ◽  
Kimberly A. Kelly ◽  
Kevin A. Herrera ◽  
Danielle L. Gray ◽  
Lisa Olshansky
RSC Advances ◽  
2014 ◽  
Vol 4 (58) ◽  
pp. 30638-30643 ◽  
Author(s):  
Sebastián Gallardo-Fuentes ◽  
Ricardo A. Tapia ◽  
Renato Contreras ◽  
Paola R. Campodónico

The nucleophilic aromatic substitution reaction of benzohydrazide derivatives towards 2-chloro-5-nitropyrimidine is used as model system to experimentally and theoretically show that intramolecular hydrogen-bond formation operates as a perturbation that elicits a dual response at the reaction center of the transition state (TS) structure.


2021 ◽  
Author(s):  
Marziyeh Mohammadi ◽  
Fahimeh Alirezapour ◽  
Azadeh Khanmohammadi

Abstract In the current research, a comparative study of the interplay effects between cation–π and intramolecular hydrogen bond (IMHB) interactions is performed on the complexes of mesalazine with Li+, Na+, K+, Be2+, Mg2+ and Ca2+ cations using density functional theory (DFT). For this purpose, the mesalazine analogue and the equivalent values of 3-aminobenzoic acid complexes with the cited cations are selected as a set of reference points. In order to understand the mutual effects between these interactions, the descriptors of geometrical, binding energies, topological properties and charge transfer values are examined on complexes using the atoms in molecules (AIM) and natural bond orbital (NBO) analyses. Results indicate that with the exception of Be2+ complex, the coupling simultaneously weakens both of the interactions. Finally, the physical properties such as energy gap, chemical hardness as well as electronic chemical potential of complexes are systematically analyzed by using frontier molecular orbitals.


Author(s):  
Reihaneh Heidarian ◽  
Mansoureh Zahedi-Tabrizi

: Leflunomide (LFM) and its active metabolite, teriflunomide (TFM), have drawn a lot of attention for their anticancer activities, treatment of rheumatoid arthritis and malaria due to their capability to inhibit dihydroorotate dehydrogenase (DHODH) and Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH) enzyme. In this investigation, the strength of intramolecular hydrogen bond (IHB) in five analogs of TFM (ATFM) has been analyzed employing density functional theory (DFT) using B3LYP/6-311++G (d, p) level and molecular orbital analysis in the gas phase and water solution. A detailed electronic structure study has been performed using the quantum theory of atoms in molecules (QTAIM) and the hydrogen bond energies (EHB) of stable conformer obtained in the range of 76-97 kJ/mol, as a medium hydrogen bond. The effect of substitution on the IHB nature has been studied by natural bond orbital analysis (NBO). 1H NMR calculations show an upward trend in the proton chemical shift of the enolic proton in the chelated ring (14.5 to 15.7ppm) by increasing the IHB strength. All the calculations confirmed the strongest IHB in 5-F-ATFM and the weakest IHB in 2-F-ATFM. Molecular orbital analysis, including the HOMO-LUMO gap and chemical hardness, was performed to compare the reactivity of inhibitors. Finally, molecular docking analysis was carried out to identify the potency of inhibition of these compounds against PfDHODH enzyme.


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