Reductive Electropolymerization and Electrochromism of Iron(II) Complex with Styrene-Based Ligand

The benzimidazole-based ligand containing polymerizable styrene group has been prepared via condensation of picolinaldehyde derivative containing styrene moiety and benzimidazole-based hydrazine. The ligand reacted with iron(II) tetrafluoroborate and iron(II) trifluoromethanesulfonate giving red-brown complexes of Fe(II) ions of formula [FeL2]X2, where X = CF3SO3− (1) or BF4− (2). Reductive electropolymerization was used to obtain a thin layer of the polymeric complex, poly-1. Further investigation of electrochemical properties of the compound by cyclic voltammetry showed two quasi-reversible redox processes assigned to electrooxidation and electroreduction of the polymer. Spectroelectrochemical measurements confirmed that the polymer undergoes the color changes during oxidation and reduction process. The polymer in its neutral state (Fe(II)) is yellow and it exhibits absorption band at 370 nm, after oxidation to Fe(III) state absorption band shifts to 350 nm and the polymer is almost colorless. While the metal ions are reduced to Fe(I) absorption band at around 410 nm has been observed and the polymer changed its color to intense yellow. The stability of the polymer during multiple oxidation/reduction cycles has also been investigated.

Cyclodextrin-Based Hybrid Polymeric Complex to Overcome Dual Drug Resistance Mechanisms for Cancer Therapy

Drug resistance always reduces the efficacy of chemotherapy, and the classical mechanisms of drug resistance include drug pump efflux and anti-apoptosis mediators-mediated non-pump resistance. In addition, the amphiphilic polymeric micelles with good biocompatibility and high stability have been proven to deliver the drug molecules inside the cavity into the cell membrane regardless of the efflux of the cell membrane pump. We designed a cyclodextrin (CD)-based polymeric complex to deliver chemotherapeutic doxorubicin (DOX) and Nur77ΔDBD gene for combating pumps and non-pump resistance simultaneously. The natural cavity structure of the polymeric complex, which was comprised with β-cyclodextrin-graft-(poly(ε-caprolactone)-adamantly (β-CD-PCL-AD) and β-cyclodextrin-graft-(poly(ε-caprolactone)-poly(2-(dimethylamino) ethyl methacrylate) (β-CD-PCL-PDMAEMA), can achieve the efficient drug loading and delivery to overcome pump drug resistance. The excellent Nur77ΔDBD gene delivery can reverse Bcl-2 from the tumor protector to killer for inhibiting non-pump resistance. The presence of terminal adamantyl (AD) could insert into the cavity of β-CD-PCL-PDMAEMA via host-guest interaction, and the releasing rate of polymeric inclusion complex was higher than that of the individual β-CD-PCL-PDMAEMA. The polymeric inclusion complex can efficiently deliver the Nur77ΔDBD gene than polyethylenimine (PEI-25k), which is a golden standard for nonviral vector gene delivery. The higher transfection efficacy, rapid DOX cellular uptake, and significant synergetic tumor cell viability inhibition were achieved in a pump and non-pump drug resistance cell model. The combined strategy with dual drug resistance mechanisms holds great potential to combat drug-resistant cancer.

A dithiacyclam-coordinated silver(i) polymer with anti-cancer stem cell activity

A cancer stem cell (CSC) active, solution stable, silver(i) polymeric complex bearing a dithiacyclam ligand is reported.

Four Different Crystalline Products from One Reaction: Unexpected Diversity of Products of the CuCl2 Reaction with N-(2-Pyridyl)thiourea

The reaction of N-(2-pyridyl)thiourea with CuCl2 in methanol yields four different crystalline products: yellow dimeric complex, [Cu2Cl2(μ-Cl)2(L)2] (1), red polymeric complex, [Cu3Cl8L2]n (2), orange crystalline product with ionic structure, L2[CuCl4] (3), and colourless ionic compound LCl (4), where L = 2-amino-[1,2,4]thiadiazolo[2,3-a]pyridin-4-ium cation as a result of oxidative cyclization of N-(2-pyridyl)thiourea. The crystal structures of all these crystalline products have been determined by single-crystal X-ray diffraction analysis. Compound 1 involves a copper(I) ion while in 2 and 3 the copper centre is in the divalent state. 1H NMR spectra for compounds 1–3 are identical and confirm deprotonated thioamide groups of N-(2-pyridyl)thiourea and the formation of a thiadiazolopyridinium cation in solution. The hydrogen bonding and π–π stacking interactions were investigated in the solid state. In addition, all crystalline products 1–4 exhibit also S···Cl bonding interactions which consolidate the complexes into networks. The X-ray diffraction analyses indicate the absence of other crystalline phases in the crude reaction mixture.