Selective Cu(ii) sensing by a versatile AIE cyanostilbene-based gel system

Cyanostilbene-based derivatives 1-3 were designed, synthesized and fully characterized. By screening their gelating abilities, we observed that the subtle difference in the position of the pyridine nitrogen greatly affected the resulting fluorescence and gelation properties. Notably, 1 was found to be a versatile ambidextrous gelator capable of forming organo-, hydro-, and Cu(ii) specific metallogels. Furthermore, a rare organogel-to-metallogel transformation at room temperature was also observed upon exposure of the 1-DMSO/H2O gel to aqueous Cu(ii). This process, accompanied by colour and fluorescence changes, provides an effective strategy for the preparation of novel sensing soft materials

Preparation of amino acid anthraquinone oxalamide derivatives as colorimetric sensors for detection of the fluoride anion in solution and gel.

The invention relates to oxalamide derivs. of anthraquinone with general formula I [R1 is C1-6 alkyl, Ph, benzyl, or p-hydroxybenzyl; R2 is H, C1-6 alkyl, benzyl, or M+; X = (CH2)1-9] and their optical isomers and their mixts., including their prepn. and use for binding fluoride anions in soln. and gel, causing a change in color of the soln. and change in color and morphol. of the gel (phase change from gel to liq.). Thus, I (R1 is L-leucine side chain; R2 is Me; X is CH2) was prepd. by reactions of oxalyl chloride, L-leucine Me ester hydrochloride, N-benzylethylendiamine, and ethyl-N-1-anthraquinone oxamate and shown to bind fluoride anion, but not chloride, bromide, or iodide anions

Photophysical characterization and the self-assembly properties of mono- and bis-pyrene derivatives for cell imaging applications

A series of fluorescent mono-(1-4) and bis-pyrene derivatives (5-7) were synthesized and their photo-physical and self-aggregation properties in solution were fully investigated by UV-vis and fluorescence spectroscopies and dynamic light scattering (DLS). While in dilute DMSO mono-pyrene derivatives 1-4 show the characteristic features of monomer emission, bis-pyrene derivatives 5-7 display both monomer and excimer emissions, the latter attributable to a dynamic process. The gelation behaviour of these compounds was also studied, and only mono-pyrene leucine derivative 1 was found to display efficient gelation in aromatic solvents, such as toluene and p-xylene, and in a polar solvent mixture, water/DMSO (4 : 1 v/v). Finally, mono-pyrenes 1-4 showed no apparent cytotoxic impact on A549 and RD cell lines; derivatives 1-5 showed accumulation within both live and fixed cells, and macropinocytosis was found to be the main pathway for 5 to enter into the cells

Fluoride-responsive organogelator based on oxalamide-derived anthraquinone

Anthraquinone derived oxalamide gelator 1 forms with aromatic solvents and alcohols very stable gels which selectively respond to the presence of fluoride anion by colour change and/ or gel-to-sol transition

Self-Complementary Dimers of Oxalamide-Functionalized Resorcinarene Tetrabenzoxazines

Self‐complementarity is a useful concept in supramolecular chemistry, molecular biology and polymeric systems. Two resorcinarene tetrabenzoxazines decorated with four oxalamide groups were synthesized and characterized. The oxalamide groups possessed self‐complementary hydrogen bonding sites between the carbonyls and amide groups. The self‐complementary nature of the oxalamide groups resulted in self‐included dimeric assemblies. The hydrogen bonding interactions within the tetrabenzoxazines gave rise to the formation of dimers, which were confirmed by single‐crystal X‐ray diffractions analysis and supported by NMR spectroscopy and mass spectrometry. The self‐included dimers were connected by numerous and strong intermolecular N−H⋅⋅⋅O and C−H⋅⋅⋅O hydrogen bonds supplemented with C−H⋅⋅⋅π interactions, forming one‐dimensional polymers, which were then further linked into three‐dimensional networks.peerReviewe

Preparation of potentially porous, chiral organometallic materials through spontaneous resolution of pincer palladium conformers

Understanding the mechanism by which advanced materials assemble is essential for the design of new materials with desired properties. Here, we report a method to form chiral, potentially porous materials through spontaneous resolution of conformers of a PCP pincer palladium complex ({2,6-bis[(di-t-butylphosphino)methyl]phenyl}palladium(II)halide). The crystallisation is controlled by weak hydrogen bonding giving rise to chiral qtz-nets and channel structures, as shown by 16 such crystal structures for X = Cl and Br with various solvents like pentane and bromobutane. The fourth ligand (in addition to the pincer ligand) on palladium plays a crucial role; the chloride and the bromide primarily form hexagonal crystals with large 1D channels, whereas the iodide (presumably due to its inferior hydrogen bonding capacity) forms monoclinic crystals without channels. The hexagonal channels are completely hydrophobic and filled with disordered solvent molecules. Upon heating, loss of the solvent occurs and the hexagonal crystals transform into other non-porous polymorphs. Also by introducing a strong acid, the crystallisation process can be directed to a different course, giving several different non-porous polymorphs. In conclusion, a number of rules can be formulated dictating the formation of hexagonal channel structures based on pincer palladium complexes. Such rules are important for a rational design of future self-assembling materials with applications in storage and molecular recognition.peerReviewe

Design, synthesis, and cytostatic activity of novel pyrazine sorafenib analogs

© 2016, Springer Science+Business Media New York. The current study is focused on a series of sorafenib analogs as potential antitumor agents. We have designed and synthesized nine novel pyrazine analogs 6a–i differing in amide and/or urea regions. Two alternative strategies for the preparation of title compounds were applied. The first strategy involved ether formation between 4-hydroxyphenyl urea 3 and 5-chloro-pyrazine-2-carboxamides 4. In the second strategy, ether functionality was introduced in the molecule before urea moiety and included preparation of 5-(4-aminophenoxy)-N-alkylpyrazine-2-carboxamides 5 and their reaction with 4-chloro-3-(fluoromethyl)phenyl isocyanate. Cytostatic activity of the title compounds was evaluated in vitro against a panel of cancer cell lines. Most of the tested compounds showed strong antiproliferative activity in the low micromolar range. 5-/4-[3-(4-chloro-3-trifluoromethyl-phenyl)-ureido]-phenoxy/-pyrazine-2-carboxylic acid (4-chloro-3-trifluoromethylphenyl)-amide (6g) was the most active compound (IC50 0.9–7.5 μM) and showed comparable or stronger activity than sorafenib, but also similar cytotoxicity to normal human fibroblast cells. Two compounds, namely, 5-/4-[3-(4-bromophenyl)-ureido]-phenyloxy/-pyrazine-2-carboxylic acid cyclopentylamide (6c) and 5-/4-[3-(4-chloro-3-trifluoromethyl-phenyl)-ureido]-phenoxy/-pyrazine-2-carboxylic acid cyclopentylamide (6h), exerted cytostatic activities that surpassed the effects observed with sorafenib in three cancer cell lines (HepG2, HeLa, A549, IC50 0.6–0.9 μM). Similar to sorafenib, compound 6h proved to be cytotoxic to normal human fibroblast cells, whereas compound 6c did not diminish proliferative capacity of these cells and could be regarded as the most promising derivative. Additional biological studies on the c-Raf activity using Western blot method revealed that antiproliferative activity of 6h could be at least partially attributed to its inhibitory effect on c-Raf activation similar to sorafenib. In contrast, 6c did not inhibit the activity of c-Raf, which implies that other cell signaling pathways govern its antiproliferative effects. Taking into account structural differences between compounds 6c and 6h, it is plausible to believe that the substituent in urea part of the molecule is essential for the interaction with c-Raf.status: publishe