Fluorescent Supramolecular Organic Frameworks Constructed by Amidinium-Carboxylate Salt Bridges.

We report here a set of fluorescent supramolecular organic frameworks (SOFs) that incorporate aggregation-induced emission (AIE) units within their frameworks. The fluorescent SOFs of this study were constructed by linking the tetraphenylethylene (TPE)-based tetra(amidinium) cation TPE4+ and aromatic dicarboxylate anions through amidinium-carboxylate salt bridges. The resulting self-assembled structures are characterized by fluorescence quantum yields in the range of 4.6∼14 %. This emissive behavior is ascribed to a combination of electrostatic interactions and hydrogen bonds that operate in concert to impede motions that would otherwise lead to excited state energy dissipation. Single-crystal X-ray diffraction analyses revealed that the length of the dicarboxylate anion bridges has a considerable impact on the structural features of the resulting frameworks. Nevertheless, all SOFs prepared in the context of the present study were found to display emissive features characteristic of TPE-based AIE luminogens with only a modest dependence on the structural specifics being seen. The SOFs reported here could be reversibly "broken up" and "reformed" in response to acid/base stimuli. This reversible structural behavior is consistent with their SOF nature.

Nanoparticles composed of the tea polysaccharide-complexed cationic vitamin B12-conjugated glycogen derivative.

Tea polysaccharides exhibit multiple important bioactivities, but very few of them can be absorbed through the small intestine. To enhance the absorption efficacy of tea polysaccharides, a cationic vitamin B12-conjugated glycogen derivative bearing the diethylenetriamine residues (VB12-DETA-Gly) was synthesized and characterized using FTIR, 1H NMR, and UV-vis spectroscopy. An acidic tea polysaccharide (TPSA) was isolated from green tea. The TPSA/VB12-DETA-Gly complexed nanoparticles were prepared, which showed positive zeta potentials and were irregular spherical nanoparticles in the sizes of 50-100 nm. To enable the fluorescence and UV-vis absorption properties of TPSA, a Congo red residue-conjugated TPSA derivative (CR-TPSA) was synthesized. The interactions and complexation mechanism between the CR-TPSA and the VB12-DETA-Gly derivatives were investigated using fluorescence spectroscopy, resonance light scattering spectroscopy, and UV-vis spectroscopy. The results indicated that the electrostatic interaction could play a major role during the CR-TPSA and VB12-DETA-Gly-II complexation processes. The TPSA/VB12-DETA-Gly nanoparticles were nontoxic and exhibited targeted endocytosis for the Caco-2 cells, and showed high permeation through intestinal enterocytes using the Caco-2 cell model. Therefore, they exhibit potential for enhancing the absorption efficacy of tea polysaccharides through the small intestinal mucosa.

Calix[4]pyrrole-Crosslinked Porous Polymeric Networks for the Removal of Micropollutants from Water.

Calix[4]pyrrole-based porous organic polymers (P1-P3) for removing organic micropollutants from water were prepared. A bowl-shaped α,α,α,α-tetraalkynyl calix[4]pyrrole and diketopyrrolopyrrole monomer were crosslinked via Sonogashira coupling to produce a 3D network polymer, P1. P1 proved too hydrophobic for use as an adsorbent and was converted to the corresponding neutral polymer P2 (containing carboxylic acid groups) and its anionic derivative P3 (containing carboxylate anion groups). Anionic P3 outperformed P2 in screening studies involving a variety of model organic micropollutants of different charge, hydrophilicity and functionality. P3 proved particularly effective for cationic micropollutants. The theoretical maximum adsorption capacity (qmax,e ) of P3 reached 454 mg g-1 for the dye methylene blue, 344 mg g-1 for the pesticide paraquat, and 495 mg g-1 for diquat. These uptake values are significantly higher than those of most synthetic adsorbent materials reported to date.

Nickel-catalyzed reductive methylation of alkyl halides and acid chlorides with methyl p-tosylate.

Methylation of unactivated alkyl halides and acid chlorides under Ni-catalyzed reductive coupling conditions led to efficient formation of methylated alkanes and ketones using methyl p-methyl tosylate as the methylation reagent. Moderate to excellent coupling yields as well as excellent functional group tolerance were observed under the present mild and easy-to-operate reaction conditions.

Mild ketone formation via Ni-catalyzed reductive coupling of unactivated alkyl halides with acid anhydrides.

Ni-catalyzed ketone formation through mild reductive coupling of a diverse set of unactivated alkyl bromides and iodides with particularly aryl acid anhydrides was successfully developed using zinc as the terminal reductant. These conditions also allow direct coupling of alkyl iodides with aryl acids in the presence of Boc(2)O and MgCl(2).

Tetra-kis-(µ-benzoato-κO:O')bis{[4-(di-methyl-amino)-pyridine-κN]zinc(II)}.

In the centrosymmetric binuclear title complex, [Zn(2)(C(7)H(5)O(2))(4)(C(7)H(10)N(2))(2)], the Zn atoms [Zn⋯Zn = 3.0037 (6) Å] are bridged by four benzoate ligands. Each of the Zn atoms assumes an approximately square-pyramidal environment, with four O atoms in a plane and the pyridine N atom at the apical site.

Tris(3,5-dimethyl-1H-pyrazole-κN)(pyridine-2,6-dicarboxyl-ato-κO,N,O)cobalt(II) monohydrate.

The reaction of Co(NO(3))(2)·3H(2)O with pyridine-2,6-dicarboxylic acid and 3,5-dimethyl-1H-pyrazole in a 1:1:3 molar ratio affords the title complex, [Co(C(7)H(3)NO(4))(C(5)H(8)N(2))(3)]·H(2)O. The Co(II) atom is coordinated by one pyridine-2,6-dicarboxyl-ate chelating ligand and three 3,5-dimethyl-1H-pyrazole ligands in a distorted octa-hedral geometry. Hydrogen-bonding interactions involving the coordinated carboxylate group, 3,5-dimethyl-1H-pyrazole and water help to consolidate the crystal structure.