Bromo Functional Groups Research Articles

Synthesis, crystal growth and supramolecular chemistry of 4-dimethylaminopyridinium salts of benzoates and a phenolate ion

Abstract Seven novel molecular salts were synthesized from the commonly available 4-dimethylaminopyridine organic base and benzoic acid derivatives contain additional functional groups. Benzoic acids with additional hydroxyl, nitro, amino, and bromo functional groups, were successfully employed and investigated their role in non-covalent interactions within the supramolecular chemistry of heterosynthons solid-state architecture. The collection of all 4-dimethylamopyrinium salts of benzoates and phenolate was accomplished through the utilization of conventional solvent evaporation technique. The resulting molecular salts were afforded by deprotonation of the acidic moiety such as COOH, or OH to the ring N of 4-dimethylaminopyridine, establishing a strong charged-assisted hydrogen bond between the deprotonated group (benzoate or phenolate) and protonated ring N. The structure of compounds was fully elucidated by single X-ray diffraction, powder X-ray diffraction, 1H NMR, FT-IR, and thermogravimetric analysis. The crystal packing is interpreted by the strong charge-assisted N–H⋯O hydrogen bond between the NH+ and the corresponding deprotonated group and O–H⋯O, N–H⋯N hydrogen bonding. The analysis concluded that C–H⋯O, CH3⋯O, C–H⋯π, CH3⋯π, π–π, C–H⋯Br, and CH3⋯Br contacts contribute significantly to stabilizing and expanding the high-dimensionality (2D–3D framework) of the structures. The structures were thoroughly explored for their various bonding and nonbonding interactions, as well as their supramolecular chemistry in detail. The antimicrobial activities of all compounds were evaluated using the Oxford cup method.

Synthesis of BR2 complexes of α-pyrrolyl dipyrrins

A series of BR2 complexes of α-pyrrolyl dipyrrin were synthesized from BF2 complex of α-pyrrolyl dipyrrin (3-pyrrolyl BODIPY) by treating it with various alkyl- and aryl magnesium halides under mild Grignard reaction conditions. The BR2 complexes were functionalized at α-position of the appended pyrrole ring with formyl, chloro and bromo functional groups and these functionalized BR2 complexes were used further to prepare various novel derivatives of BR2 complexes. The BR2 complexes were characterized by HR mass, NMR, absorption, fluorescence, and electrochemical techniques. Two of the BR2 complexes were structurally characterized by X-ray crystallography. Our studies revealed that the substitution of fluorine atoms at the boron center of 3-pyrrolyl BODIPYs with different alkyl/aryl groups significantly alters their structural, spectral and electrochemical properties. The DFT studies also support the alteration of the electronic properties of the BR2 complexes.

Chan-Lam cross-coupling reaction based on the Cu2S/TMEDA system

A catalyst based on the readily available Cu2S/TMEDA system using a stable copper(I) source was developed for the Chan-Lam cross-coupling reaction. The capability of the catalyst was demonstrated with 1H-benzo[d]imidazol-2(3H)-one, 1H-benzo[d]imidazole, and 1H-imidazole together with electron-deficient, electron-rich, and sterically demanding boronic acids at room temperature in the presence of atmospheric oxygen to give the cross-coupling products in moderate to excellent yields. In addition, the coupling reaction of 1H-benzo[d]imidazole with several pinacol or neopentylglycol boronates indicated further potential of the catalyst. The reaction conditions tolerate the hydroxyl and bromo functional groups. The catalytic system also enables to synthesize the mono-N-substituted anilines from primary aliphatic amines. However, the two model compounds for the secondary and aromatic amines, piperidine and aniline, do not react. Two sterically demanding products with the restricted CN bond rotation, synthesized by the N-arylation of 1H-benzo[d]imidazol-2(3H)-one with o-tolylboronic acid, enabled to confirm the atropisomers prepared by the Chan-Lam cross-coupling reaction. Furthermore, an example of one-pot Chan-Lam and Suzuki-Miyaura reaction has been reported.

Synthesis of C<sub>2</sub>-Symmetrically Functionalized Dibromo- Hexa-peri-hexabenzocoronene

A novel dibromo-substituted HBC derivative, whose side chains contains oxygen heteroatoms, has been successfully synthesized by Diels-Alder reaction of asymmetric synthesis. It possesses bromo-functional groups to provide possibility to further synthesize more complex HBC derivatives. The final compound’s structure has been confirmed by1HNMR,13CNMR and MALDI-TOF mass spectrometry.

Hyperbranched Polymers with a Degree of Branching of 100% Prepared by Catalyst Transfer Suzuki−Miyaura Polycondensation

Hyperbranched polymers with a degree of branching of 100% were prepared by catalyst transfer Suzuki-Miyaura polymerization of AB(2) monomers carrying one boronic acid and two aromatic bromo functional groups; in contrast, Suzuki-Miyaura polymerization of the same AB(2) monomers using a traditional catalyst afforded hyperbranched polymers with a branching degree of only approximately 56%. This is a nice example of controlling the topology of hyperbranched polymers via the catalyst.

Covalent functionalization of multi-walled carbon nanotube surfaces by conjugated polyfluorenes

The outer surface of multi-walled carbon nanotubes (MWCNTs) was successfully modified with 7-bromo-9,9-dioctylfluorene-2-carbaldehyde by using 1,3-dipolar cycloaddition of azomethine reaction to introduce bromo functional groups. The peripheral bromo functional groups can be used to further react with AB-type monomers through Suzuki polycondensation to afford the PF-functionalized MWCNTs, which are of a cable-like structure. Through covalent connection to MWCNTs, the fluorescence of polyfluorenes was completely quenched by the MWCNTs, indicating a fast photo-induced electron transfer from polyfluorenes to MWCNTs.

Synthesis of hyperbranched polymers with precise conjugation length

AbstractA set of AB2 type monodisperse conjugated oligomers carrying two bromo functional groups and one boronic ester functional group were prepared by iterative deprotection and Sonogashira cross‐coupling reactions. Suzuki polycondensation of these AB2 type monodisperse oligomers afforded hyperbranched polymers. The hyperbranched conjugated polymers we prepared possess not only precisely controlled conjugation length like monodisperse conjugated oligomers but also the structural feature of hyperbranched polymers. Optical property investigation demonstrated that the maximum absorption and emission wavelength red‐shifted along with the increasing of the conjugation length between the two branching points and the hyperbranched structure could effectively reduce the aggregation of the conjugated polymer chains. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1084–1092, 2007