Solvated-Ion-Pairing-Sensitive Molecular Bistability Based on Copper(I)-Coordinated Pyrimidine Ring Rotation

2012 ◽  
Vol 52 (1) ◽  
pp. 369-380 ◽  
Author(s):  
Michihiro Nishikawa ◽  
Kuniharu Nomoto ◽  
Shoko Kume ◽  
Hiroshi Nishihara
Keyword(s):  
Ion Pairing ◽  
Pyrimidine Ring ◽  
Ring Rotation ◽  
Molecular Bistability

Steric Interference on the Redox-conjugated Pyrimidine Ring Rotation of Mono- and Dinuclear Copper Complexes with (4-Methyl-2-pyrimidinyl)imine Ligands

2014 ◽  
Vol 43 (7) ◽  
pp. 1037-1039 ◽  
Author(s):  
Yohei Hattori ◽  
Michihiro Nishikawa ◽  
Tetsuro Kusamoto ◽  
Shoko Kume ◽  
Hiroshi Nishihara
Keyword(s):  
Copper Complexes ◽  
Pyrimidine Ring ◽  
Dinuclear Copper ◽  
Ring Rotation ◽  
Imine Ligands

Ion Pairing and Dielectric Decrement in Glycosaminoglycan Brushes

2020 ◽  
Author(s):  
James Sterling ◽  
Wenjuan Jiang ◽  
Wesley M. Botello-Smith ◽  
Yun L. Luo
Keyword(s):  
Molecular Dynamics ◽  
Ion Pairs ◽  
Mean Field ◽  
Salt Bridge ◽  
Ion Pairing ◽  
Donnan Potential ◽  
Mean Field Models ◽  
Ion Exclusion ◽  
Dynamics Simulations ◽  
Contact Ion Pairs

Molecular dynamics simulations of hyaluronic acid and heparin brushes are presented that show important effects of ion-pairing, water dielectric decrease, and co-ion exclusion. Results show equilibria with electroneutrality attained through screening and pairing of brush anionic charges by cations. Most surprising is the reversal of the Donnan potential that would be expected based on electrostatic Boltzmann partitioning alone. Water dielectric decrement within the brush domain is also associated with Born hydration-driven cation exclusion from the brush. We observe that the primary partition energy attracting cations to attain brush electroneutrality is the ion-pairing or salt-bridge energy associated with cation-sulfate and cation-carboxylate solvent-separated and contact ion pairs. Potassium and sodium pairing to glycosaminoglycan carboxylates and sulfates consistently show similar abundance of contact-pairing and solvent-separated pairing. In these crowded macromolecular brushes, ion-pairing, Born-hydration, and electrostatic potential energies all contribute to attain electroneutrality and should therefore contribute in mean-field models to accurately represent brush electrostatics.

Synthesis of Novel 3(N,N-dialkylamino)alkyl/phenyl Substituted Thieno [2,3-d]pyrimidinones as H1-Anti-Histaminic and Antimicrobial Agents

2019 ◽  
Vol 15 (1) ◽  
pp. 63-70
Author(s):  
Shiv Dev Singh ◽  
Arvind Kumar ◽  
Firoz Babar ◽  
Neetu Sachan ◽  
Arun Kumar Sharma
Keyword(s):  
Antimicrobial Activity ◽  
Potassium Hydroxide ◽  
Antimicrobial Agents ◽  
Pyrimidine Ring ◽  
Antimicrobial Activities ◽  
Screening Methods ◽  
Chlorpheniramine Maleate ◽  
In Vivo Screening

Background: Thienopyrimidines are the bioisoster of quinazoline and unlike quinazoline exist in three isomeric forms corresponding to the three possible types annulation of thiophene to the pyrimidine ring viz thieno[2,3-d] pyrimidine, thieno[3,2-d] pyrimidine and thieno[3,4-d]pyrimidine. Heterocyclic containing the thienopyrimidinone moiety exhibits various pronounced activities such as anti-hypertensive, analgesic and anti-inflammatory, antiviral, platelet aggregation inhibitory, antiprotozoal bronchodilatory, phosphodiesterase inhibitory, antihistaminic, antipsychotic and antimicrobial activity. Objective: Synthesis of novel 3(N,N-dialkylamino)alkyl/phenyl substituted thieno[2,3-d]pyrimidinones as H1-anti-histaminic and antimicrobial agents. Methods: A series of 3-[(N,N-dialkylamino)alkyl/phenyl]-2-(1H)thioxo-5,6,7,8-tetrahydrobenzo(b) thieno(2,3-d)pyrimidine-4(3H)-ones[4a-d], their oxo analogous [5a-d] and 3-[(N,N-dialkylamino)alkyl]- 2-chlorophenyl-5,6,7,8-tetrahydrobenzo(b)thieno(2,3-d)pyrimidine- 4 (3H)-ones[6a-d]derivative were synthesized from 2-amino-4,5,6,7-tetrahydrobenzo(b)thiophene-3-carboxylic acid by nucleophilic substitution of different N,N-dialkyl alkylene/phenylene diamines on activated 3-acylchloride moiety followed by cyclocondensation with carbon disulfide and ethanolic potassium hydroxide to get [4a-d] and in second reaction by condensation with 4-chlorobenzoyl chloride to get [6a-d] by single pot novel innovative route. The oxo analogous [5a-d] were prepared by treating derivatives [4a-d] with potassium permagnate in ethanolic KOH. The synthesized compound were evaluated for H1-antihistaminic and antimicrobial activities. Results: All synthesized compounds exhibited significant H1-antihistaminic activity by in vitro and in vivo screening methods and data were verified analytically and statistically. The compound 4a, 4b, 5a and 5b showed significant H1-antihistaminiic activity than the reference standard chlorpheniramine maleate. The compound 6d, 6c, 5c and 4c exhibited significant antimicrobial activity.

The effect of acceptor modification upon the synthesis of dinucleoside phosphates catalyzed by non-specific ribonucleases of Penicillium claviforme

1979 ◽  
Vol 44 (2) ◽  
pp. 613-625 ◽  
Author(s):  
Valentina I. Gulyaeva ◽  
Antonín Holý
Keyword(s):  
Reaction Center ◽  
Hydroxy Group ◽  
Pyrimidine Ring ◽  
Phosphate Group ◽  
Mutual Orientation ◽  
Acceptor Molecule ◽  
Heterocyclic Base ◽  
Sugar Moiety ◽  
Cyclic Phosphate ◽  
Penicillium Claviforme

The present paper studies the effect of the modification of heterocyclic base, sugar moiety and the presence of phosphate group on the nucleoside acceptors in the synthesis of dinucleoside phosphates from adenosine 2',3'-cyclic phosphate as donor, catalyzed by nonspecific acidic extracellular and intracellular ribonucleases from Penicillium claviforme. The enzyme binds specifically the acceptor molecule, preferring cytosine nucleosides. It requires the presence of the whole sugar moiety, an exact mutual orientation of the heterocyclic base and the reaction center (5'-hydroxy group), and a suitable conformation of the acceptor molecule. The enzyme-acceptor bond is homochiral and the presence of the N3-H group in the pyrimidine ring is important. The reaction between the donor and the acceptor is bimolecular and is competitively inhibited by some purine nucleosides.

Sign in / Sign up

Export Citation Format

Share Document