Calixarenes, sensor

Li DQ, Ma M (2000) Surface acoustic wave microsensors based on cyclodextrin coatings. Sens Actuators B 69 75-84 Liu CJ, Lin JT, Wang SH, Jiang JC, Lin 03 (2005) Chromogenic calixarene sensors for amine detection. Sens Actuators... 

In contrast to the well developed calixarene sensors of the potentiometric type, chemical sensors based on membrane permeability changes are still in its initial stage. In the present study the permeability of LB calix[4]resorcinarene was found to be controlled by the presence... 

The use of arachidic acid and different amphiphilic calixarenes for modifying of field effect transistor sensors and determination of some volatile organic contaminants will be considered. 

Stmctural and chemical modification of urethane containing polymer matri-ces with macrocycles - calixarenes having reactive hydrazide groups have been carried out and stmcture, physico chemical and sensor properties of polyure-thanesemicarbazides (PUS) synthesised have been studied. The polymers obtained (on the base of polypropylene glycol MM 1000 and polysiloxane diol MM 860, hexamethylene diisocyanate and calixarene dihydrazide) are identified by IR-spectroscopy, size exclusion chromatography (SEC), DSC, WAXS and SAXS methods. 

Kimura and coworkers [17], Diamond [18], and Damien et al. [19] have described that the polymeric calix-[4]arenes have been used as ionophores in ion selective electrodes for Na (based on calixarene esters and amides) and for Na and Cs (based on p-alkylcalixarene acetates). The electrodes are stated to function as poten-tiometric sensors as well, having good selectivity for primary ion, virtually no response to divalent cations, and being stable over a wide pH range. 

Applicability in biological ion assay is an important factor for biocompatible potentio-metric ion sensors. Attempts were made to determine Na" " concentrations in human blood sera by using silicone-rubber membrane Na+-ISFETs based on (5) [Fig. 17(a)] [29]. The found values for Na concentration in undiluted, 10-fold diluted, and 100-fold diluted serum samples are in good agreement with the Na" " calibration plots. Even in the undiluted serum samples, only a slight potential shift was observed from the calibration. This indicates that the calixarene-based silicone-rubber-membrane Na+-ISFETs are reliable on serum Na assay. For comparison with the silicone-rubber membrane, Na -ISFETs with corresponding plasticized-PVC membrane containing (2) or (5) were also tested for the Na assay. The found values of Na" " concentration... 

R. Ludwig and N.T.K. Dzung, Calixarene-based molecules for cation recognition. Sensors 2, 397—416... 

The sensor covalently joined a bithiophene unit with a crown ether macrocycle as the monomeric unit for polymerization (Scheme 1). The spatial distribution of oxygen coordination sites around a metal ion causes planarization of the backbone in the bithiophene, eliciting a red-shift upon metal coordination. They expanded upon this bithiophene structure by replacing the crown ether macrocycle with a calixarene-based ion receptor, and worked with both a monomeric model and a polymeric version to compare ion-binding specificity and behavior [13]. The monomer exhibited less specificity for Na+ than the polymer. However, with the gradual addition of Na+, the monomer underwent a steady blue shift in fluorescence emission whereas the polymer appeared to reach a critical concentration where the spectra rapidly transitioned to a shorter wavelength. Scheme 2 illustrates the proposed explanation for blue shift with increasing ion concentration. 

Fig. 10.15. Calixarene-based PET sensors (PET-17 Aoki I. et al. (1992) J. Chem. Soc., Chem. Commun. 730. PET-18 Unob F. et al. (1998) Tetrahedron Lett. 39, 2951).

Box 10.2 Calixarene-based fluorescent molecular sensors for sodium ions... 

E-3 (Figure 10.26) is the first example of an ionophoric calixarene with appended fluorophores, demonstrating the interest in this new class of fluorescent sensors. The lower rim contains two pyrene units that can form excimers in the absence of cation. Addition of alkali metal ions affects the monomer versus excimer emission. According to the same principle, E-4 was designed for the recognition of Na+ the Na+/K+ selectivity, as measured by the ratio of stability constants of the complexes, was indeed found to be 154, while the affinity for Li+ was too low to be determined. 

Fig. 10.34. Sensors based on acyclic, macrocyclic and calixarene ruthenium—bipyridyl (from Beer, P. D. (1996) Chem. Commun. 689).

Selective complexation of cations by crown ethers 17 [lb, lg] and calixarenes 18 [If] depending on the rings size was proposed to be used in sensors. 

By bridging calixarenes 226 [9], forming their dimers like 227 with one or several bridges [10] or by combining them with crown ethers 228[11], calixarenes with several novel architectures and complexation behaviour have been obtained. Some of such systems have been proposed as prospective sensors. 

A plastic sodium membrane is now predominantly based on a neutral carrier (ETH 2120) that ensures sufficient sensitivity, selectivity and lifetime for the sensor. Some other compounds such as neutral carriers ETH 157, 227, 4120, calixarenes, crown ethers and hemisphe-rands have been proposed. Anionic influence observed during measurements in undiluted urine may be circumvented by dilution of the sample. 

G.A. Evtyugin, I.I. Stoikov, C.K. Budnikov and E.E. Stoikova, A cholinesterase sensor based on a graphite electrode modified with 1,3-disub-stituted calixarenes, J. Anal. Chem., 58 (2003) 1151-1156. 

The quantitation of undesired enantiomers in drug raw materials is one of the objectives of the pharmaceutical industry. Several calixarene derivatives were investigated as fluorescence sensors for chiral pharmaceutical compounds. The mechanism of these examples is based on different fluorescence quenching of the calixarenes by the two enantiomeric forms of a specific analyte. 

Arimori, S., Davidson, M. G., Fyles, T. M., Hibbert, T. G., James, T. D., Kociok-Kohn, G. I., Synthesis and structural characterisation of the first bis(bora)calixarene a selective, bidentate, fluorescent fluoride sensor. Chem. Commun. 2004, 1640-1641. 

The majority of the devices mentioned thus far rely on the Hofmeister series for anion selectivity. However, for anions that deviate from this series, organometallic receptors can be utilised. The type of ligand or metal centre will influence the sensor selectivity due to the characteristics of the electron acceptance of the complex. An interesting development that is being explored here is the use of calixarenes. These have previously found use as cation-selective species, but with suitable substitution are now being incorporated within anion-selective devices. Compounds suitable as receptors for halides [61],benzoate [61] and acetate [62] have been developed. Reinhoudt and his co-workers have reported the production of a POj-selective CHEMFET based on a uranyl cation immobilised within a salophene ligand (Fig. 5), which shows selectivity over more lipophilic anions such as Br" and NOj [63]. 

Because of expected electrical, electrochemical, optical, chemo-sensor, and other properties of the ball-type Pcs, several metallo and metal-free ball-type Pcs with different linkers have been reported. Metallo and metal free ball-type Pcs containing four calyx[4]arene units as linkers have been synthesized, Fig. 1 [37], The structures of compounds 1-3 were confirmed by UV-vis, IR, 1II-NMR, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and elemental analysis. Because of their unique structure and versatile complexation properties [38], calixarenes were found to be one type of interesting compounds to be incorporated into Pc. The cone conformation of the t-butylcalix[4]arene direct... 

The area covered is very widespread and the role of the calixarene molecules reach from a simple platform or skeleton on which to assemble chiral centers to an inherent part of the chiral structure. Biologically active molecules or derivatives are involved as well as artificial ligands and their metal complexes. Chiral calixarenes have been used as stationary phases in analytical separations or as host molecules in sensors. Basic properties of calixarenes, such as their conformational stabilities, have been studied with chiral derivatives as well as more... 

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