Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 24
Filtrar
Mais filtros

Base de dados
Tipo de documento
Intervalo de ano de publicação
1.
Acta Crystallogr E Crystallogr Commun ; 80(Pt 8): 863-866, 2024 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-39108781

RESUMO

The aryl diester compound, 2-methyl-1,4-phenyl-ene bis-(3,5-di-bromo-benzoate), C21H12Br4O4, was synthesized by esterification of methyl hydro-quinone with 3,5-di-bromo-benzoic acid. A crystalline sample was obtained by cooling a sample of the melt (m.p. = 502 K/DSC) to room temperature. The mol-ecular structure consists of a central benzene ring with anti-3,5-di-bromo-benzoate groups symmetrically attached at the 1 and 4 positions and a methyl group attached at the 2 position of the central ring. In the crystal structure (space group P), mol-ecules of the title aryl diester are located on inversion centers imposing disorder of the methyl group and H atom across the central benzene ring. The crystal structure is consolidated by a network of C-H⋯Br hydrogen bonds in addition to weaker and offset π-π inter-actions involving the central benzene rings as well as the rings of the attached 3,5-di-bromo-benzoate groups.

2.
Chem Commun (Camb) ; 60(6): 758-761, 2024 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-38126447

RESUMO

Incremental, single-atom substitutions of Se-based chalcogen bond (Ch-bond) donors with stronger donating Te centers were implemented in two new triptycene tris(1,2,5-chalcogenadiazole) tectons. The appreciably more favorable Ch-bonding ability of the Te-based donors promotes assembly of low-density networks and more stable Ch-bonded organic frameworks (ChOFs).

3.
IUCrdata ; 7(Pt 9): x220895, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-36337458

RESUMO

The title compound, C20H14I2N2O2, a di-iodo-Schiff base, crystallizes in space group Pbca with one mol-ecule per asymmetric unit. The mol-ecular structure reveals two intra-molecular O-H⋯N hydrogen bonds that give the mol-ecule a twisted structure with non-coplanar rings. In the crystal structure, the mol-ecular packing is stabilized by π-π stacking, hydrogen- and halogen-bonding (C-H⋯I; O⋯I) inter-actions.

4.
Angew Chem Int Ed Engl ; 61(1): e202110753, 2022 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-34755431

RESUMO

Tetrahedral main-group compounds are normally configurationally stable, but P-epimerization of the chiral phosphiranium cations syn- or anti-[Mes*P(Me)CH2 CHPh][OTf] (Mes*=2,4,6-(t-Bu)3 C6 H2 ) occurred under mild conditions at 60 °C in CD2 Cl2 , resulting in isomerization to give a syn-enriched equilibrium mixture. Ion exchange with excess [NBu4 ][Δ-TRISPHAT] (Δ-TRISPHAT=Δ-P(o-C6 Cl4 O2 )3 ) followed by chromatography on silica removed [NBu4 ][OTf] and gave mixtures of syn- and anti-[Mes*P(Me)CH2 CHPh][Δ-TRISPHAT]⋅x[NBu4 ][Δ-TRISPHAT]. NMR spectroscopy showed that isomerization proceeded with epimerization at P and retention at C. DFT calculations are consistent with a mechanism involving P-C cleavage to yield a hyperconjugation-stabilized carbocation, pyramidal inversion promoted by σ-interaction of the P lone pair with the neighboring ß-carbocation, and ring closure with inversion of configuration at P.

5.
J Am Chem Soc ; 143(48): 20207-20215, 2021 12 08.
Artigo em Inglês | MEDLINE | ID: mdl-34818002

RESUMO

The manner of bonding between constituent atoms or molecules invariably influences the properties of materials. Perhaps no material family is more emblematic of this than porous frameworks, wherein the namesake modes of connectivity give rise to discrete subclasses with unique collections of properties. However, established framework classes often display offsetting advantages and disadvantages for a given application. Thus, there exists no universally applicable material, and the discovery of alternative modes of framework connectivity is highly desirable. Here we show that chalcogen bonding, a subclass of σ-hole bonding, is a viable mode of connectivity in low-density porous frameworks. Crystallization studies with the triptycene tris(1,2,5-selenadiazole) molecular tecton reveal how chalcogen bonding can template high-energy lattice structures and how solvent conditions can be rationalized to obtain molecularly programmed porous chalcogen-bonded organic frameworks (ChOFs). These results provide the first evidence that σ-hole bonding can be used to advance the diversity of porous framework materials.

6.
Acta Crystallogr E Crystallogr Commun ; 77(Pt 7): 700-702, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-34513014

RESUMO

The title compound, C14H6F4O2, crystallizes with half of a mol-ecule per asymmetric unit and exhibits bond lengths and angles typical of α-diketones. A network of C-H⋯F contacts and π-π stacking inter-actions is observed within the structure.

7.
J Am Chem Soc ; 142(49): 20513-20518, 2020 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-33253553

RESUMO

High-affinity guests have been reported for the macrocyclic host cucurbit[7]uril (CB[7]), enabling widespread applications, but hindering CB[7] materials from being returned to their guest-free state for reuse. Here, we present polyhedral boron clusters (carboranes) as strongly binding, yet easily removable, guests for CB[7]. Aided by a Pd-catalyzed coupling of an azide anion, we prepared boron-functionalized 9-amino-ortho-carborane that binds to CB[7] with a Ka ≈ 1010 M-1. Upon basic treatment, ortho-carborane readily undergoes deboronation to yield anionic nido-carborane, a poor guest for CB[7], facilitating recovery of guest-free CB[7]. We showcase the utility of the modified ortho-carborane guest by recycling a CB[7]-functionalized resin. With this report, we introduce stimuli-responsive decomplexation as an additional consideration in the design of high-affinity host-guest complexes.


Assuntos
Compostos de Boro/química , Hidrocarbonetos Aromáticos com Pontes/química , Imidazóis/química , Azidas/química , Catálise , Cinética , Paládio/química
8.
J Org Chem ; 85(22): 14516-14526, 2020 11 20.
Artigo em Inglês | MEDLINE | ID: mdl-32627554

RESUMO

Kinetic separation of the commercially available cis/trans-(+)-limonene oxide mixture by ring opening with primary phosphido nucleophiles LiPHR (R = ferrocenyl, Ph, Cy, t-Bu, Mes* (Mes* = 2,4,6-(t-Bu)3C6H2)), followed by treatment with aqueous NH4Cl and H2O2, gave unreacted cis-(+)-limonene oxide and diastereoenriched mixtures of the secondary phosphine oxides (SPOs) PHR(trans-(+)-Lim-OH)(O), which could be separated by chromatography and/or recrystallization. This one-pot synthesis uses a cheap chiral material and commercially available primary phosphines to control the configuration of the new P-stereogenic SPOs, which are potentially useful as ligands for metal complexes in asymmetric catalysis.

9.
J Org Chem ; 85(17): 11116-11123, 2020 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-32654484

RESUMO

An investigation into the crystalline to amorphous phase transitions of prepared 1,3,6-substituted pentafulvenes showed the expected reversible heated melt and cooling recrystallization in only a few examples. Systematic incorporation of bulky substituents at the 6-position of the fulvene ring led to the nonreversible thermal behavior, rendering phases that were locked into glassy, vitrified states. These molecular glasses produced physically translucent and amorphous features with glass transition temperatures in the range of 61-77 °C, comparable with high-strength plastics such as polyethylene terephthalate. Additionally, the melting point transitions and the resulting heat of fusion values were found to be directly influenced by the nature of the 6-position substituent. Single crystal X-ray crystallography showed that in some cases, fulvenes possessing fused aromatics exhibited a high degree of intermolecular π-π stacking. These results point to a class of molecular glass formers as host materials possessing tunable bulk properties for potentially new optical applications.

10.
Inorg Chem ; 59(14): 9807-9823, 2020 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-32614596

RESUMO

Four groups of rare-earth complexes, comprising 11 new compounds, with fluorinated O-donor ligands ([K(THF)6][Ln(OC4F9)4(THF)2] (1-Ln; Ln = Ce, Nd), [K](THF)x[Ln(OC4F9)4(THF)y] (2-Ln; Ln = Eu, Gd, Dy), [K(THF)2][Ln(pinF)2(THF)3] (3-Ln; Ln = Ce, Nd), and [K(THF)2][Ln(pinF)2(THF)2] (4-Ln; Ln = Eu, Gd, Dy, Y) have been synthesized and characterized. Single-crystal X-ray diffraction data were collected for all compounds except 2-Ln. Species 1-Ln, 3-Ln, and 4-Ln are uncommon examples of six-coordinate (Eu, Gd, Dy, and Y) and seven-coordinate (Ce and Nd) LnIII centers in all-O-donor environments. Species 1-Ln, 2-Ln, 3-Ln, and 4-Ln are all luminescent (except where Ln = Gd and Y), with the solid-state emission of 1-Ce being exceptionally blue-shifted for a Ce complex. The emission spectra of the six Nd, Eu, and Dy complexes do not show large differences based on the ligand and are generally consistent with the well-known free-ion spectra. Time-dependent density functional theory results show that 1-Ce and 3-Ce undergo allowed 5f → 4d excitations, consistent with luminescence lifetime measurements in the nanosecond range. Eu-containing 2-Eu and 4-Eu, however, were found to have luminescence lifetimes in the millisecond range, indicating phosphorescence rather than fluorescence. The performance of a pair of multireference models for prediction of the Ln = Nd, Eu, and Dy absorption spectra was assessed. It was found that spectroscopy-oriented configuration interaction as applied to a simplified model in which the free-ion lanthanide was embedded in ligand-centered Löwdin point charges performed as well (Nd) or better (Eu and Dy) than canonical NEVPT2 calculations, when the ligand orbitals were included in the treatment.

11.
Acta Crystallogr E Crystallogr Commun ; 76(Pt 6): 896-899, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32523759

RESUMO

The title compounds, 6-cyclo-propyl-1,3-diphenylfulvene, C21H18, [systematic name: 5-(cyclo-propyl-methyl-idene)-1,3-di-phen-yl-cyclo-penta-1,3-diene], 1, and 6-(2,3-di-meth-oxy-naphth-yl)-1,3-diphenylfulvene, C30H24O2, {systematic name: 5-[(3,4-di-meth-oxy-naphthalen-2-yl)methyl-idene]-1,3-di-phenyl-cyclo-penta-1,3-di-ene}, 2, were prepared from 1,3-di-phenyl-cyclo-penta-diene, pyrrolidine, and the corresponding aldehydes in an ethano-lic solution. Each structure crystallizes with one mol-ecule per asymmetric unit and exhibits the alternating short and long bond lengths typical of fulvenes. A network of C-H⋯C ring inter-actions as well as C-H⋯O inter-actions is observed, resulting in the compact packing found in each structure.

12.
Dalton Trans ; 49(45): 16245-16251, 2020 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-32379258

RESUMO

Bromination of the luminescent borane, anti-B18H22, via electrophilic substitution using AlCl3 and Br2, yields the monosubstituted derivative 4-Br-anti-B18H21 as an air-stable crystalline solid. In contrast to the unsubstituted parent compound, 4-Br-anti-B18H21 possesses dual emission upon excitation with UV light and exhibits fluorescence at 410 nm and phosphorescence at 503 nm, with Φtotal = 0.07 in oxygen-free cyclohexane. Increased oxygen content in cyclohexane solution quenches the phosphorescence signal. The fluorescent signal intensity remains unaffected by oxygen, suggesting that this molecule could be used as a ratiometric oxygen probe.

13.
Acta Crystallogr E Crystallogr Commun ; 75(Pt 6): 838-842, 2019 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31391978

RESUMO

The synthesis and crystal structures of a series of 6-aryl-fuvlenes (fulvene is 5-methyl-idene-cyclo-penta-1,3-diene) with varying methyl-ation patterns on the 6-phenyl substituent are reported, namely 6-(3-methyl-phen-yl)-1,3-di-phenyl-fulvene (C25H20), 6-(4-methyl-phen-yl)-1,3-di-phenyl-fulvene (C25H20), 6-mesityl-3-di-phenyl-fulvene (C27H24) and 6-(2,3,4,5,6-penta-methyl-phen-yl)-1,3-di-phenyl-fulvene (C29H28). The bond lengths are typical of those observed in related fulvenes. A network of C-H⋯π ring inter-actions consolidates the packing in each structure.

14.
Acta Crystallogr E Crystallogr Commun ; 75(Pt 8): 1102-1107, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31417773

RESUMO

Five new crystal structures of perfluoro-pyridine substituted in the 4-position with phen-oxy, 4-bromo-phen-oxy, naphthalen-2-yl-oxy, 6-bromo-naphthalen-2-yl-oxy, and 4,4'-biphen-oxy are reported, viz. 2,3,5,6-tetra-fluoro-4-phen-oxy-pyridine, C11H5F4NO (I), 4-(4-bromo-phen-oxy)-2,3,5,6-tetra-fluoro-pyridine, C11H4BrF4NO (II), 2,3,5,6-tetra-fluoro-4-[(naphthalen-2-yl)-oxy]pyridine, C15H7F4NO (III), 4-[(6-bromo-naphthalen-2-yl)-oxy]-2,3,5,6-tetra-fluoropyridine, C15H6BrF4NO (IV), and 2,2'-bis-[(perfluoro-pyridin-4-yl)-oxy]-1,1'-biphenyl, C22H8F8N2O2 (V). The dihedral angles between the aromatic ring systems in I-IV are 78.74 (8), 56.35 (8), 74.30 (7), and 64.34 (19)°, respectively. The complete mol-ecule of V is generated by a crystallographic twofold axis: the dihedral angle between the pyridine ring and adjacent phenyl ring is 80.89 (5)° and the equivalent angle between the biphenyl rings is 27.30 (5)°. In each crystal, the packing is driven by C-H⋯F inter-actions, along with a variety of C-F⋯π, C-H⋯π, C-Br⋯N, C-H⋯N, and C-Br⋯π contacts. Hirshfeld surface analysis was conducted to aid in the visualization of these various influences on the packing.

15.
Acta Crystallogr E Crystallogr Commun ; 75(Pt 8): 1153-1157, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31417783

RESUMO

The syntheses and crystal structures of the title compounds, C14H8F4N2O2 and C14H8F4N2O3, are reported. In each crystal, the packing is driven by C-H⋯F inter-tactions, along with a variety of C-H⋯O, C-O⋯π, and C-F⋯π contacts. Hirshfeld surface analysis was conducted to aid in the visualization of these various influences on the packing: they showed that the largest contributions to the surface contacts arise from H⋯F/F⋯H inter-actions, followed by H⋯H and O⋯H/H⋯O.

16.
Data Brief ; 19: 1638-1642, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30229036

RESUMO

This data article describes a detailed synthetic strategy and experimental data for the synthesis of brominated fulvene chromophores as reactive precursors/monomers for conjugated organic materials. Metal-mediated coupling reactions of brominated fulvenes would result in conjugated small molecules or polymers that would find application as organic light emitting diodes (OLEDs) and photovoltaic (PV) applications.

17.
Acta Crystallogr E Crystallogr Commun ; 74(Pt 9): 1190-1194, 2018 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-30225097

RESUMO

The synthesis and structural properties of a series of chromium tricarbonyl 'piano-stool' complexes bearing substituted penta-fulvene ligands were studied. The complexes, tricarbon-yl(1,3,6-tri-phenyl-fulvene)chromium(0) benz-ene hemisolvate, [Cr(C24H18)(CO)3]·0.5C6H6 (I), tricarbon-yl[1,3-di-phen-yl-6-(3-vinyl-phen-yl)fulvene]chromium(0), [Cr(C26H20)(CO)3] (II), and tricarbon-yl[1,3-diphenyl-6-(pyren-1-yl)fulvene]chromium(0), [Cr(C34H22)(CO)3] (III), each have a distorted octa-hedral geometry, with the fulvene coordinated in a π-η2:π-η2:π-η2 fashion. Significant deviation of the exocyclic fulvene double bond from the cyclo-penta-diene plane accompanies coordination. Evidence of non-covalent π-π inter-actions was observed in both (I) and (III), with centroid-to-centroid distances ranging from 3.330 (8) to 3.494 (8) Å.

18.
Acta Crystallogr E Crystallogr Commun ; 73(Pt 9): 1279-1281, 2017 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-28932454

RESUMO

The title compound, [IrCl(C12H8NO)2{(CH3)2SO}]·H3CCN or [IrCl(fppy)2(DMSO)]·H3CCN [where fppy is 4-(pyridin-2-yl)benzaldehyde and DMSO is dimethyl sulfoxide], is a mononuclear iridium(III) complex including two fppy ligands, a sulfur-coordinating DMSO ligand, and one terminal chloride ligand that define a distorted octa-hedral coordination sphere. The complex crystallizes from 1:1 DMSO-aceto-nitrile as an aceto-nitrile solvate. In the crystal, weak C-H⋯O and C-H⋯N hydrogen-bonding inter-actions between adjacent complexes and between the aceto-nitrile solvent and the complex consolidate the packing.

19.
J Org Chem ; 81(20): 9630-9638, 2016 10 21.
Artigo em Inglês | MEDLINE | ID: mdl-27689910

RESUMO

A series of 1,3-diphenyl-6-alkyl/arylfulvenes was prepared, and the electrochemical properties were investigated. The addition of phenyl groups about the fulvene raised the reduction potential and helped to stabilize the electrochemically generated radical anion. The addition of various functional groups onto the phenyl ring at the 6-position of 1,3,6-triphenylfulvene results in a linear free energy relationship between reduction potential and the Hammett substituent constant, σ. Further extending the conjugation at the 6-position of 1,3-diphenyl-6-arylfulvenes increases the reversibility of the redox reactions, but does not appear to further stabilize the generated radical anion. This in-depth investigation provides evidence that the compounds studied may have utility in light-harvesting applications.

20.
Chem Commun (Camb) ; 52(30): 5242-5, 2016 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-26980553

RESUMO

New polymers containing intact pendant-fulvene moieties have been successfully prepared from 1,3-phenyl-6-norbornenylfulvene via ring-opening metathesis polymerization (ROMP). The prepared polyfulvenes have unique electrochemical and photophysical properties which make them interesting candidates for light harvesting materials.


Assuntos
Ciclopentanos/química , Plásticos/química , Ciclopentanos/síntese química , Técnicas Eletroquímicas , Luz , Plásticos/síntese química , Polimerização
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA