Difluoroboron Complexes Research Articles

1,3-Dimethyl-5-(3,4,5-tris(alkoxy)benzoyl) barbituric acid derivatives and their liquid crystalline difluoroboron complexes: Synthesis, characterization and comparative investigations of mesomorphic, thermotropic and thermo-morphologic properties

A series of 1,3-dimethyl-5-(3,4,5-tris(alkoxy)benzoyl) barbituric acid derivatives 1a–4a with various chain length were synthesized by our group for the first time through the addition of 1,3-dimethyl barbituric acid to 3,4,5-tris(alkoxy)benzoyl chloride at room temperature in presence of pyridine. For preparation of their difluoroboron complexes, the derivatives 1a–4a reacts with borontrifluoride in the presence of triethylamine affording 1b–4b in moderate yields. All derivatives and complexes have been fully characterized by MS, FT-IR and multinuclear NMR spectroscopy. We also explored their liquid crystal properties by using POM, OM, CTW and DSC techniques. The results show that 3b and 4b with longer alkyl chain are monomorphic mesogens and exhibited enantiotropic thermotropic liquid crystalline mesophases. Investigation of their mesomorphic, thermo-morphologic and thermotropic properties is presented in this work.

Efficient fluorophores based on pyridyl-enolato and enamido difluoroboron complexes: Simple alternatives to boron-dipyrromethene (bodipy) dyes

Simple [N,O] and [N,N]β-pyridyl or quinolyl enolato/enamido difluoroboron complexes are easily accessible and highly luminescent with good photophysical properties, comparable to BODIPY benchmark dyes. Complete characterization by multinuclear NMR and by single crystal structure analysis as well as pertinent photophysical data are reported.

Synthesis and Photophysical Properties of Difluoroboron Complexes of Curcuminoid Derivatives Bearing Different Terminal Aromatic Units and a meso-Aryl Ring

The synthesis of nine curcuminoids and their difluoroboron complexes is described, with seven of them containing a meso-phenyl ring. Dynamic (19)F NMR confirmed the fact that rotation of that meso-aryl fragment is restricted in the latter systems at room temperature and become allowed at higher temperature (>45 °C). The molecular structure of a meso-substituted derivative in the solid state showed that the phenyl ring lies in a highly twisted plane with respect to the mean curcuminoid plane. The photophysical properties of the nine compounds were investigated in solvents of different polarity. Meso-substitution with a phenyl ring has little influence on fluorescence emission properties in solution, radiative and nonradiative kinetic constants being similar for meso- and nonsubstituted compounds, which is in contrast to the case of BODIPY derivatives. However, introduction of an electron donor p-methoxy group at the meso-phenyl ring leads to small perturbation of the curcuminoid π-system fluorescence emission. We also report the influence of the meso-phenyl group on the emission properties of the aggregated solids.

Synthesis of quinolizin-2-one and pyrido[1,2-a]azepin-2-one derivatives from difluoroboron complexes of aroylacetones and O-methyllactims

O-Methyllactims react at the methyl group of difluoroboron complexes of aroylacetones with the formation of condensation products, novel difluoroboron chelates of 1-aryl-4-(piperi-din-2-ylidene)butane-1,3-diones and 1-aryl-4-(azepan-2-ylidene)butane-1,3-diones, which upon the action of concentrated HCl in ethanol are transformed into the corresponding quino-lizin-2-one and pyrido[1,2-a]azepin-2-one derivatives.

Hydroxyl-directed trifluoromethylation of hydrazones

The trifluoromethylation of hydrazones derived from salicyl aldehydes and N-aminopiperidine and N-aminomorpholine through the generation of chelate difluoroboron complexes, which subsequently interact with Me3SiCF3 in the presence of sodium acetate, has been developed.

Synthesis of new chelating ligands containing two pyrazole fragments

7-[Pyrazol-3(5)-yl]4,5,6,7-tetrahydro-1H-indazole and 6-[pyrazol-3(5)-yl]-1,4,5,6-tetrahydrocyclopenta[c]pyrazole, potential chelating ligands, were synthesized by condensation of 2-acetylcyclohexanone and 2-acetylcyclopentanone difluoroboron complexes with dimethylformamide dimethyl acetal followed by cyclization with hydrazine hydrate.

Synthesis of 5-aroylmethylpyrazoles and their hydrazones from dif luoroboron chelates of aroylacetones

A convenient method for the synthesis of 5-aroylmethylpyrazoles and their hydrazones from difluoroboron complexes of aroylacetones, acetals of amides, and hydrazines was developed.

Formation of Fluorescent and Nonfluorescent Difluoroboron Complexes in the Reaction of BF3Etherate with 21H,24H‐Bilin‐1,19‐dione Derivatives

ABSTRACTOn reaction with BF3 etherate, in the presence of base, bile pigments of the biliverdin and 2,3‐dihydrobiliverdin type form two kinds of difluoroboron chelates. In one of them, which displays intensive photoluminescence, the boron atom is complexed through the nitrogen atoms of the dipyrrin moiety of the ligand molecule. In the second type of chelates, which have been characterized in the present work for the first time, the boron atom is complexed through the nitrogen atoms of the pyrrole and one of the terminal lactam rings. These BF2 complexes are devoid of manifest fluorescence. Their 1H‐NMR spectra show clear through‐space 1H‐19T spin‐spin couplings that served for structure elucidation. Bile pigment analogs, in which the pyrrolic HN group has been replaced by N‐CH3 or by divalent heteroatoms, such as an O or S atom, form only the latter type of BF2 chelates.

Synthesis and Conformational Studies of Urobilin Difluoroboron Complexes. Unprecedented Solvent-Dependent Chiroptical Properties of the BF2 Chelate of an Urobilinoid Analogue1

Optically active difluoroboron complexes of both a conventional urobilin derivative (3) and a nonracemizable urobilin analogue (4) have been synthesized for the first time, and their structures have been determined, in solution, by means of 1H{1H}NOE difference experiments. Whereas the BF2 chelate 5 occurs in a “stretched” 9Z,4(5)-ac, 5(6)-sc,10(11)sp,14(15)-sc,15(16)-ac conformation in both dimethylformamide and methylene chloride solutions, the preferred conformation (6 or 7) of the difluoroboron complex of 4 is dependent on the solvent, thus giving rise to opposite CD curves in the aforementioned solvents. As revealed by X-ray diffraction analysis, however, only conformer 6 is present in the solid state, in which extended intermolecular hydrogen bonding involving the lactam groups takes place, independently of the solvent used for crystallization. Conformer 7, on the contrary, is stabilized, in solution, by intramolecular NH···F bonds, as evidenced by measurements of “through-space” 1H−19F spin−spin coupling.

Spectroscopic Characterization and in vitro and in vivo Screening of Difluoro-Boron Complexes of NO and NS Donor Ligands

Abstract Stereochemical and biochemical aspects of some difluoroboron complexes of the types BF2(NS) and BF2(NO) with ligands having (NS) and (NO) donor systems have been described. Based on IR, 1H NMR, 13C NMR, 19F NMR, and 11B NMR spectral studies, a tetracoordinated state of boron has been established. In order to assess their growth inhibiting potency the ligands and their fluoroboron complexes have been tested in vitro against a number of pathogenic fungi and bacteria at different concentrations and were found to possess remarkable fungicidal and bactericidal properties. The testicular morphology, testicular sperm density, sperm motility, density of cauda epididymal spermatozoa, and fertility in mating trails and biochemical parameters of reproductive organs with 2-acetylthiophene thiosemicarbazone, 2-acetylnaphthalene semicarbazone, and their fluoro complexes in vivo have also been examined and discussed.

Reactions of coordinated molecules. 35. Carbon-carbon bond formation between adjacent acyl ligands in (metalla-.beta.-diketonato)difluoroboron complexes of iron, manganese, and rhenium

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTReactions of coordinated molecules. 35. Carbon-carbon bond formation between adjacent acyl ligands in (metalla-.beta.-diketonato)difluoroboron complexes of iron, manganese, and rheniumP. Galen Lenhert, C. M. Lukehart, and K. SrinivasanCite this: J. Am. Chem. Soc. 1984, 106, 1, 124–130Publication Date (Print):January 1, 1984Publication History Published online1 May 2002Published inissue 1 January 1984https://doi.org/10.1021/ja00313a026RIGHTS & PERMISSIONSArticle Views72Altmetric-Citations17LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (949 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts