The synthesis and anion binding properties of a new class of calixpyrrole analogue, containing two carbazole subunits in lieu of two of the four acetone bridging elements normally found in calix[4]pyrrole, is described. The compound exists in a winglike structure in the solid state, as judged from single-crystal X-ray diffraction analyses of both the free system and the corresponding benzoate anion complex. Evidence for anion binding in dichloromethane solution was obtained from static fluorescent quenching experiments; these latter revealed a slight preference for acetate relative to other carboxylate anions (e.g., benzoate, oxalate, succinate), as well as various other anionic substrates (i.e., chloride and dihydrogen phosphate). No evidence of binding was observed in the case of bromide, nitrate, and hydrogen sulfate.

A new colorimetric anion sensor 4 allows for selective 'naked-eye' differentiation of F-, AcO- and H2PO4- with similar basicity.

In this communication, we describe a polymerizable, heteroditopic salt receptor, based on an amino acid scaffold, which is able to bind sodium salts of chloride, acetate and nitrate. A poly(butyl methacrylate) derivative containing receptor was then prepared. In contrast to receptor copolymer is capable of extracting sodium nitrate from aqueous media.

Modification of ultrasmall gold nanoparticles (AuNPs) with the lipoic acid derivative of folic acid was found to enhance their accumulation in the cancer cell, as compared to AuNPs without addressing units. The application of lipoic acid enabled the control of the gold nanoparticle functionalities leading to enhanced solubility and allowing for attachment of both the folic acid and the cytotoxic drug, doxorubicin. More robust attachment of doxorubicin to the nanoparticle through the amide bond resulted in toxicity comparable with that of the drug alone, opening a new perspective for designing more potent, but less toxic nanopharmaceuticals. The increased uptake was accompanied by pronounced nuclear accumulation and observable cytotoxicity. Doxorubicin binding via covalent amide bonds enhanced stability of the whole drug vehicle and provided much better control over doxorubicin release in the cell environment, as compared to physical adsorption or pH sensitive bonding commonly used for anthracycline carriers. Confocal microscopy revealed that the bond was stable in the cytoplasm for 22 h. The ability to slow down the rate of drug release may be crucial for the application in sustained anticancer drug delivery. Biological analyses performed using MTT assay and confocal microscopy confirmed that the ultrasmall AuNPs with the lipoic acid derivative of folic acid exhibit relatively low cytotoxicity, however when loaded with a chemotherapeutic, they cause a significant reduction in the cell viability.

Compound 1 was designed and prepared as a heteroditopic ion-pair receptor that contains two urea groups for anion complexation and N-benzyl-18-crown-6 for cation recognition. These ion-binding domains are assembled together by the l-ornithine scaffold. Qualitative cation coordination studies of receptor 1, supported by quantitative data received for monotopic N-(3-nitrobenzyl)-aza-18-crown-6 (3a), have shown that 1 has a strong affinity for Na, K and NH cations. Anion binding studies revealed that in the absence of cations coordinated to 1 (TBA salts), anions are bound with a relatively moderate strength with the selectivity: BzO > AcO > Cl> NO > Br. However, in the presence of cations coordinated to the N-benzyl-18-crown-6 the anion binding affinity increases considerably with the notable exception of carboxylates. For example, chloride binding is increased by over five times in the presence of K cations and the selectivity trend for salt binding is: KCl > KOBz > KOAc > KNO > KBr. Liquid/liquid extraction studies revealed that receptor 1 is an effective extractant for KCl and NHCl salts from aqueous to organic phase.