Search results for "bond"

Anion Recognition by a Bioactive Diureidodecalin Anionophore: Solid-State, Solution, and Computational Studies

2018

Recent work has identified a bis-(p-nitrophenyl)ureidodecalin anion carrier as a promising candidate for biomedical applications, showing good activity for chloride transport in cells yet almost no cytotoxicity. To underpin further development of this and related compounds, a detailed structural and binding investigation is reported. Crystal structures of the transporter as five solvates confirm the diaxial positioning of urea groups while revealing a degree of conformational flexibility. Structures of complexes with Cl−, Br−, NO3 −, SO4 2− and AcO−, supported by computational studies, show how the binding site can adapt to accommodate these anions. 1H NMR binding studies revealed exception…

2015

The heterotetracene skeleton of the title molecule, C23H14Br2N2OS, is defined by linear annulation of four six-membered rings, including two N heteroatoms. This moiety is nearly planar (r.m.s. deviation = 0.055 Å), with a slight twist of 4.1 (2)° between the two halves of the aromatic system. The dihedral angle between the least-squares plane of the skeleton and the benzyl group is 24.5 (3)°; the C—S—C angle involving the benzylsulfanyl group is 99.2 (4)°. In the crystal, molecules are π-stacked in an antiparallel fashion along [110], with a distance between the aromatic planes of 3.47 (2) Å. Intermolecular N—H...O hydrogen bonds form chains extending parallel to [001] and bridge the antipa…

Effect of π-Electron Delocalization on Tautomeric Equilibria – Benzoannulated 2-Phenacylpyridines

2006

Most benzoannulated 2-methylpyridines react with phenyllithium and substituted alkyl benzoates to give the corresponding 2-phenacylpyridines. 3-Methylisoquinoline is transformed into 2-benzoyl-3-methyl-1-phenyl-1,2-dihydroisoquinoline under these conditions, but replacement of phenyllithium with lithium isopropylcyclohexylamide is effective for production of 3-phenacylisoquinolines. Except in the cases of some substituted 6-phenacylphenanthridines, tautomeric mixtures of benzoannulated 2-phenacylpyridines in chloroform solution always contain the ketimine forms.(Z)-2-(2-Hydroxy-2-phenylvinyl)pyridine (enolimine) forms also contribute if the pyridine ring is not benzoannulated or if such ann…

Development and validation of a procedure for estimating the hydrophobicity of structurally unrelated compounds by micellar liquid chromatography

1999

Reversed-phase liquid chromatography has been used most often to estimate values of log P, but despite years of study, there is no universally accepted method of performing these estimations. The main problem has to do with the fact that the hydrophobic parameter, log k w , depends on the hydrogen bond acceptor-donor character of the compounds. The use of micellar mobile phases to perform these estimations is evaluated here, and the influence of the nature of the surfactant (anionic, cationic, and nonionic) on the log k-log P relationships is studied. The use of a nonionic surfactant, such as Brij35, to prepare the mobile phases provided adequate results regardeless of the hydrogen bond acc…

New acridinium trifluoromethanesulfonate stacks induced in the presence of organotin(IV) complexes

2013

Abstract Three new crystalline architectures based on acridinium trifluoromethanesulfonate salts [C13H10N]+[CF3SO3]– have been isolated as single crystals from the reaction of the dimeric hydroxo di-n-butylstannane trifluoromethanesulfonato complex [n-Bu2Sn(OH)(H2O)(CF3SO3)]2 (1) with acridine (C13H9N, Acr), in dichloromethane at room temperature. When an equimolar mixture of anthracene (C14H10, Ant) and acridine is initially used, the crystallization of a sandwich-type arrangement occurs, leading to the intercalation of one molecule of anthracene between two acridium trifluoromethanesulfonate salt molecules. In the three X-ray structures reported, the crystal packing involves the contribut…

Organotin(IV) trifluoromethanesulfonates chemistry: Isolation and characterization of a new di-n-butyl derivative presenting a Sn3O3 core

2012

Abstract Reaction of the dimeric hydroxo di-n-butylstannane trifluoromethanesulfonato complex [n-Bu2Sn(OH)(H2O)(CF3SO3)]2 (1) with a mixture of anthracene (C14H10, Ant) and phenazine (C12H8N2, Phz) in dichloromethane at room temperature yielded the novel di-n-butyltin(IV) trifluoromethanesulfonate salt {[n-Bu2Sn(H2O)]2O·n-Bu2Sn(OH)2}(CF3SO3)2 (2), together with the co-crystallization of phenazinium trifluoromethanesulfonate salts ([C12H9N2][CF3SO3], PhzH) collected in the solid state in two distinct self-assembled architectures, 3 and 4, showing π–π stacking interactions, and involving the intercalation of free molecules of phenazine and anthracene, respectively. Complex 2 is a cationic tri…

Effect of molecular geometry and extended conjugation on the performance of hydrogen-bonded semiconductors in organic thin-film field-effect transist…

2021

A general synthetic method has been used for the condensation of the 7-azaindole substructure at both extremes of centrosymmetric fused polyheteroaromatic systems. Four different aromatic spacers (benzene, naphthalene, anthracene and pyrene) that modify the molecular geometry and the π-conjugated surface have proved the ability of 7-azaindole to work as a building block that can control the crystal packing through reciprocal hydrogen bond interactions. Two possible self-assembled columnar arrangements have been observed as a result of the π–π interactions between hydrogen-bonded ribbon-like supramolecular structures. A detailed comparative analysis of the molecular organisation driven by hy…

Self-assembly of 1- and 2-Dimensional Multicompartmental Arrays via the 2-Aminopyrimidine H-Bonding Motif and Selective Guest Inclusion

2000

Abstract The H-bond mediated self-assembly of aminopyrimidine substituted anthracene derivatives 4 and 5, respectively, generate 1- and 2-dimensional multicompartmental arrays in the solid state as revealed by X-ray crystallographic analysis. The derived ‘pigeon-hole’ lattice is defined by syn-coplanar positioning of anthracene moieties at a distance of ca. 7 A, allowing the formation of selective clathrate-type inclusion entities with guests of appropriate shape and size, in particular phenazine, which presents both structural and interactional complementarity. These data provide insight into the interplay of the different structural and interactional features of the molecular components t…

Electronic Interactions in a New π-Extended Tetrathiafulvalene Dimer

2006

The first pi-extended tetrathiafulvalene (exTTF) dimer in which the two exTTF units are covalently connected by 1,3-dithiole rings has been obtained in a multistep synthetic procedure involving the Ullmann cross-coupling reaction by using copper(I) thiophene-2-carboxylate (CuTC). The electronic spectrum reveals a significant electronic interaction between the exTTF units. The electrochemical study carried out by cyclic voltammetry in solution and in thin-layer conditions, and the electrochemical simulation and spectroelectrochemical (SEC) measurements confirm the electronic communication and show that the oxidation of dimer 14 occurs as two consecutive 2 e(-) processes D(0)-D(0)-->D(2+)-D(0…

Antibacterial and white spot lesions preventive effect of an orthodontic resin modified with silver-nanoparticles

2021

Background To evaluate the antibacterial property of a modified orthodontic resin with different concentrations of silver-nanoparticles (AgNPs), and quantify its preventive effect on the formation of white spot lesions (WSLs). Material and Methods An orthodontic resin (Transbond XT) was modified with four concentrations of AgNPs (1%, 0.5%, 0.1%, and 0.05%), the orthodontic resin without AgNPs was used as control. Polymerized resin discs (n=80) were submitted to Agar diffusion test on Petri dishes inoculated with Streptococcus mutans and Lactobacillus acidophilus. In addition, resin discs of each group (n=40) were placed in 96-well plates with bacterial suspensions to evaluate the colony-for…