8(meso)-Pyridyl-BODIPYs: Effects of 2,6-Substitution with Electron-Withdrawing Nitro, Chloro, and Methoxycarbonyl Groups

The introduction of electron-withdrawing groups on 8(meso)-pyridyl-BODIPYs tends to increase the fluorescence quantum yields of this type of compound due to the decrease in electronic charge density on the BODIPY core. A new series of 8(meso)-pyridyl-BODIPYs bearing a 2-, 3-, or 4-pyridyl group was synthesized and functionalized with nitro and chlorine groups at the 2,6-positions. The 2,6-methoxycarbonyl-8-pyridyl-BODIPYs analogs were also synthesized by condensation of 2,4-dimethyl-3-methoxycarbonyl-pyrrole with 2-, 3-, or 4-formylpyridine followed by oxidation and boron complexation. The structures and spectroscopic properties of the new series of 8(meso)-pyridyl-BODIPYs were investigated both experimentally and computationally. The BODIPYs bearing 2,6-methoxycarbonyl groups showed enhanced relative fluorescence quantum yields in polar organic solvents due to their electron-withdrawing effect. However, the introduction of a single nitro group significantly quenched the fluorescence of the BODIPYs and caused hypsochromic shifts in the absorption and emission bands. The introduction of a chloro substituent partially restored the fluorescence of the mono-nitro-BODIPYs and induced significant bathochromic shifts.

Cytotoxic substituted indolizines as new colchicine site tubulin polymerisation inhibitors

A potential microtubule destabilising series of new indolizine derivatives was synthesised and tested for their anticancer activity against a panel of 60 human cancer cell lines. Compounds 11a, 11b, 15a, and 15j showed a broad spectrum of growth inhibitory activity against cancer cell lines representing leukaemia, melanoma and cancer of lung, colon, central nervous system, ovary, kidney, breast, and prostate. Among them, compound 11a was distinguishable by its excellent cytostatic activity, showing GI₅₀ values in the range of 10–100 nM on 43 cell lines. The less potent compounds 15a and 15j in terms of GI₅₀ values showed a high cytotoxic effect against tested colon cancer, CNS cancer, renal cancer and melanoma cell lines and only on few cell lines from other types of cancer. In vitro assaying revealed tubulin polymerisation inhibition by all active compounds. Molecular docking showed good complementarity of active compounds with the colchicine binding site of tubulin.

Targeted synthesis of a polypyridyl polyoxometalate coordination complex using microwave-assisted reaction conditions

In this article, we build upon our recent efforts that have focused on demonstrating the value of microwave-assisted synthesis in polyoxometalate (POM) chemistry. Herein, we report for the first time a microwave-assisted approach that enabled the facile preparation and crystallization of a large POM-containing coordination complex. The judicious selection and reaction of a sparingly water-soluble transition-metal-substituted polyanion (TMSP) salt with the tritopic ligand 2,4,6-tris(4-pyridyl)-1,3,5-triazine (TPT) in a mixed solvent system under moderately forcing conditions yields Ba₉[(B^IIIW^VI₁₁O₃₉Co^III)₃(C₁₈H₁₂N₆)]·38H₂O in moderate yield. Crystallographic analysis reveals significant intermolecular interactions between the organic ligand and neighbouring polyanions, predominantly C-H...O(water) in nature; meanwhile, the solvated regions of the crystal show significant disorder. To supplement the crystallographic study, combustion analysis, and IR and ¹H NMR spectroscopic analyses were conducted, revealing good bulk purity and the stability of the complex in aqueous media.

Design, Synthesis, and Biological Activities of Novel Pyrazole Oxime Compounds Containing a Substituted Pyridyl Moiety

In this paper, in order to find novel biologically active pyrazole oximes, a series of pyrazole oxime compounds bearing a substituted pyridyl unit were prepared. Bioassays showed that some target compounds were found to have good acaricidal activity against Tetranychus cinnabarinus at a concentration of 500 μg/mL, compound 9q especially displayed potent acaricidal activity against T. cinnabarinus when the concentration was reduced to 100 μg/mL. Interestingly, most target compounds possessed excellent insecticidal activities against Oriental armyworm at 500 μg/mL. Moreover, some compounds were active against Aphis medicaginis and Nilaparvata lugens at 500 μg/mL. Additionally, compounds 9b, 9g, 9l, 9p, 9q, 9r, 9s, 9t, 9u, and 9v displayed significant antiproliferative activities against HepG2 cells with IC₅₀ values of 1.53-17.27 μM, better than that of the control 5-fluorouracil (IC₅₀ = 35.67 μM).

Synthesis and structural studies of two pyridine-armed reinforced cyclen chelators and their transition metal complexes

Two novel pyridine pendant-armed macrocycles structurally reinforced by an ethyl bridge, either between adjacent nitrogens (for side-bridged) or non-adjacent nitrogens (for cross-bridged), have been synthesized and complexed with a range of transition metal ions (Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺). X-ray crystal structures of selected cross-bridged complexes were obtained which showed the characteristic cis-V configuration with potential labile cis binding sites. The complexes have been characterized by their electronic spectra and magnetic moments, which show the expected high spin divalent metal complex in most cases. Exceptions are the nickel side-bridged complex, which shows a mixture of high-spin and low spin, and the cobalt cross-bridged complex which has oxidized to cobalt(III). Cyclic voltammetry in acetonitrile was carried out to assess the potential future use of these complexes in oxidation catalysis. Selected complexes offer significant catalytic potential enhanced by the addition of the pyridyl arm to a reinforced cyclen backbone.