Off-gassing from firefighter suits (nomex) as an indoor source of BTEXS.

The clothes and special equipment of firefighters can be a source of indoor air pollution. Nevertheless, it has not been investigated so far what the scale of the release of various compounds from such materials into the indoor air can be. The following study analysed the results of an experiment involving the passive measurement of concentrations of selected compounds, i.a. benzene, toluene, ethylbenzene, m,p-xylene, o-xylene, styrene, isopropylbenzene and n-propylbenzene (BTEXS) in the air of a room where firefighters' special clothing, which had been previously exposed to emissions from simulated fires, was stored. The study included simulations of fires involving three materials: wood, processed wood (OSB/fibreboard) and a mixture of plastics. After being exposed to the simulated fire environment, special clothing (so-called nomex) was placed in a sealed chamber, where passive collection of BTEXS was carried out using tube-type axial passive samplers and a gas chromatograph. Irrespective of which burned material special clothing was exposed to, the compound emitted into the air most intensively was toluene. Its rate of release from a single nomex ranges from 4.4 to 28.6 µg h-1, while the corresponding rates for the sum of BTEXS are between 9.97 and 44.29 µg h-1.

Induced ion-pair formation/ de-aggregation of rhodamine B octadecyl ester for anion optical sensing: Towards ibuprofen selective optical sensors.

A novel approach is explored to result in anion selective nanostructural optodes, that do not require the presence of selective ionophore. The sensing principle proposed is based on interactions of polarity sensitive dye with anions, leading to change of the chromophore group environment, resulting in increase of emission for increase of analyte concentration. To induce interactions of the analyte with the dye precise matching of properties of analyte and receptor is required. It is shown that the careful balancing of composition of nanostructural probes allows fine tuning of linear response range to cover lower concentration range. The model analyte studied was ibuprofen, due to its clinical and environmental relevance, lack of ionophore. As model probes rhodamine B octadecyl ester based nanostructures were prepared and applied. For optimized system turn-on responses were obtained for ibuprofen concentration change from 10-4.3 M to 10-2 M, with no effect of other anti-inflammatory drugs such as naproxen or salicylate.

Development of effective potassium acetate extractant.

Carboxylates are commonly used in the food and pharmaceutical industry and due to their extensive use, carboxylates present a significant environmental burden. In this context, valine based, heteroditopic receptor 1 was prepared and its ability to bind simultaneously potassium cation and acetate anion in water containing CH3CN solutions was demonstrated. Under liquid-liquid extraction conditions the receptor 1 was capable of extracting hydrophilic AcOK salt from aqueous solution and was proved to be nearly ten times more effective than the equimolar mixture of monotopic receptors. Furthermore, compound 1 could extract one of the most popular nonsteroidal anti-inflammatory drugs, ibuprofen (IbuOK), from relatively dilute aqueous solutions.

Complexation of 5-aminovaleric acid zwitterions in aqueous/methanol solution by heterotopic tri-cationic receptors.

Heterotopic tri-cationic receptors based on 4,10,16-triaza-18-crown-6 are capable of efficient and selective binding of the zwitterionic form of 5-aminovaleric acid (5-AVA) in aqueous/methanol solution. The cooperative participation of both cation and anion binding domains of this receptor in 5-AVA complexation was established by 1H NMR experiments and DFT calculations. Heterotopic receptors and fluorescein were used for the preparation of indicator displacement assay and this assembly was applied to selective optical sensing of 5-aminovaleric acid.

A non-multimacrocyclic heteroditopic receptor that cooperatively binds and effectively extracts KAcO salt.

Prepared in only three synthetic steps, a non-multimacrocyclic heteroditopic receptor binds potassium salts of halides and carboxylates with unusually high cooperativity, suggesting salt binding as associated ion-pairs. Unprecedented extraction of highly hydrophilic KAcO salt from water to organic solution is also demonstrated.

An ion-pair receptor comprising urea groups and N-benzyl-aza-18-crown-6: effective recognition and liquid-liquid extraction of KCl salt.

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 NH4+ 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-> NO2- > 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 > KNO2 > KBr. Liquid/liquid extraction studies revealed that receptor 1 is an effective extractant for KCl and NH4Cl salts from aqueous to organic phase.

Towards potent but less toxic nanopharmaceuticals - lipoic acid bioconjugates of ultrasmall gold nanoparticles with an anticancer drug and addressing unit.

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.

Highly effective ion-pair receptors based on 2,2-bis(aminomethyl)-propionic acid.

Compounds 2 and 3 were designed and prepared as heteroditopic ion-pair receptors. The design features a 2,2-bis(aminomethyl)propionic acid core to connect and pre-organize binding groups. The cation binding is provided by a sodium selective N-acyl aza-18-crown-6 subunit whereas for anion complexation, two urea groups (receptor 2) or two squaramide groups (receptor 3) were introduced. Beyond acting as anion binding sites, the urea and squaramide groups were used to support sodium cation complexation through metal carbonyl oxygen lone pair interactions. The receptors were found to bind sodium salts of chloride, bromide and nitrate much more strongly than the corresponding ions accompanied by counterions that do not coordinate to the receptor. For example, chloride binding to receptor 2 enhances the strength of sodium complexation by up to 23 times. Conversely, sodium binding enhances chloride recognition by a factor of three. Receptor 3 containing squaramide units, binds sodium chloride and bromide with a similar albeit lower cooperativity. Moreover, unprecedentedly tight binding of these salts was achieved, with association constants as high as log Ka = 6.52 M-1 for NaCl salt complexation.

Boosting the salt recognition abilities of L-ornithine based multitopic molecular receptors by harnessing a double cooperative effect.

A family of L-ornithine based salt receptors 1a-f was synthesized, bearing a cation binding site and multiple anion binding sites (nitrophenylurea and amide groups) that may simultaneously associate with a single anion. The variation in H-bond donor abilities of one of these anion binding sites has relatively little influence on NO2(-) anion binding when the anion is accompanied by a noncoordinating TBA cation. However, in the presence of a sodium cation, which strongly coordinates with the cation binding domain of 1a-f, the increased H-bond donor abilities of the anion binding group result in a significant enhancement of NO2(-) anion binding. A direct correlation between the anion binding site H-bond donor tendencies and the binding cooperation of sodium cations and nitrite anions was also observed. Cation complexation fixes the nitrophenylurea moiety orientation and exposes that domain to bind anions. This cation and anion cooperation induces a second cooperative effect, namely the simultaneous association of a single anion with both urea and amide binding groups. Receptor 1d was found to be highly selective for NaNO2 over sodium bromide and nitrate. A transport experiment using a bulky liquid membrane showed that this receptor can effectively transport NaNO2 from the aqueous phase through the organic phase.

Selective NaNO2 recognition by a simple heteroditopic salt receptor based on L-ornithine molecular scaffold.

This paper describes the development of a simple heteroditopic salt receptor consisting of aza-18-crown-6 (a cation binding domain), nitrophenylurea (an anion binding domain) and an additional metacrylamide group appended to the carboxylic, α-amine and δ-amino groups of L-ornithine. Detailed binding studies showed that this receptor is capable of effectively and selectively binding NaNO2 salt.

Selective ammonium nitrate recognition by a heteroditopic macrotricyclic ion-pair receptor.

The heteroditopic macrotricyclic molecular receptor 1, which bears a tripodal anion binding domain and 4,10,16-triaza-18-crown-6 cation recognition domain, proves to be an effective ion-pair receptor. In the absence of the cobound cation (TBA(+) salts) receptor 1 preferably binds nitrate and nitrite over other anions, including basic anions such as acetate or dihydrogenphosphate. Ammonium cation binding by the 4,10,16-triaza-18-crown-6 subunit significantly enhances the strength of the nitrate and nitrite complexation at the triamide recognition site of the receptor. In the presence of ammonium cations, the association constants of nitrate binding reach an impressive value of 1050 M(-1) in highly polar DMSO-d6. Interestingly, the binding of other anions such as chloride and bromide is not enhanced in the presence of a cobound NH4(+) cation. The increased affinity of [1·NH4(+)]PF6(-) for anionic species is attributed to a strong cooperative effect that arises from the properly positioned binding sites in the receptor 1 cavity, thus allowing for the formation of the ion pair. Under liquid/liquid conditions, receptor 1 is able to extract NH4NO3 from an aqueous to an organic phase, as inferred from (1)H NMR spectroscopic and nitrite/nitrate colorimetric analyses.

Tuning the binding properties of a new heteroditopic salt receptor through embedding in a polymeric system.

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.

A selective chromogenic chemosensor for carboxylate salt recognition.

A new heteroditopic chromogenic chemosensor bearing a crown ether substituted at the intraannular position with a nitrophenylthiourea moiety has been synthesized. The binding behavior of this sensor was investigated by (1)H NMR spectroscopy and UV-vis spectroscopy. The receptor binds in a cooperative fashion to both a potassium cation and a carboxylate anion whereas a sodium cation sequesters an anion from the anion-receptor complex. The binding events are confirmed by selective color changes of the chemosensor solution.

Calix[4]pyrrole[2]carbazole: a new kind of expanded calixpyrrole.

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 selective colorimetric anion sensor based on an amide group containing macrocycle.

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