Search results for "HYDROGEN"

3,4-Dihydro-2H-pyrrole-2-carbonitriles: Useful Intermediates in the Synthesis of Fused Pyrroles and 2,2′-Bipyrroles

2016

Various heterocyclic structures containing the pyrrole moiety have been synthesized from easily accessible 3,4-dihydro-2H-pyrrole-2-carbonitriles in one-pot procedures. 5,6,7,8-Tetrahydroindolizines, 2,3-dihydro-1H-pyrrolizines as well as 6,7,8,9-tetrahydro-5H-pyrrolo[1,2-a]azepines were obtained from these precursors in high yields in an alkylation/annulation sequence. The same conditions were applied in the synthesis of a 5,8-dihydroindolizine, which could easily be transformed to the corresponding indolizine by dehydrogenation. Furthermore, oxidative couplings of 3,4-dihydro-2H-pyrrole-2-carbonitriles with copper(II)-salts furnished 2,2'-bipyrroles as well as 5,5'-bis(5-cyano-1-pyrroline…

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…

Highly selective fluorescence detection of hydrogen sulfide by using an anthracene-functionalized cyclam-CuII complex

2013

An anthracene-functionalised cyclam-copper(II) complex for the detection of HS- in aqueous environments has been prepared. This probe displays poor fluorescence but can selectively and sensitively detect HS- anions in water over other anions, biothiols and common oxidants such as H2O2 through remarkably enhanced emission. This turn-on response in the presence of the HS- anion is ascribed to a demetallation reaction that inhibits emission quenching observed in the initial complex as a result of the presence of the paramagnetic Cu2+ centre. Moreover, real-time fluorescence imaging measurements confirm that probe [Cu(1)](2+) can be easily used to detect intracellular HS- at micromolar concentr…

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…

Understanding the ring current effects on magnetic shielding of hydrogen and carbon nuclei in naphthalene and anthracene

2008

The local response to an external magnetic field normal to the molecular plane of naphthalene and anthracene was investigated via current density and magnetic shielding density maps. The Biot-Savart law shows that the deshielding caused by pi-ring currents in naphthalene is stronger for alpha- than for beta-protons due to geometrical factors. The shielding tensor of the carbon nuclei in both molecules is strongly anisotropic and its out-of-plane component determines the up-field chemical shift of (13)C in nuclear magnetic resonance spectra. The pi-ring currents flowing beyond the C-skeleton in front of a probe carbon nucleus, and on remote parts of the molecular perimeter, yield positive co…

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…