Thiourea sensor

Li H, Xu J, Yan H (2009) Ratiometric fluorescent determination of cysteine based on organic nanoparticles of naphthalene-thiourea-thiadiazole-linked molecule. Sensor Actuat B-Chem... 

Thioureas are most commonly prepared from reaction of isothiocyanates with amines. Also there are some reports on reactions of anime or carbodiimides with several thionating reagents. AA -Disubstituted thioureas bearing double NH groups have been developed as sensors, and as catalysts because of their hydrogen bonding ability. A,A -Disubstituted thiourea-linked sugar chains have been prepared by the reaction of isothiocyanate with amine. 

Thioureas-binding site can be introduced to molecules like anthraquinone and is for use in various kinds of anion or fluoride sensors. Thiourea-based sensor are generally designed to recognize anion through an intermolecular hydrogen bonding.167 171... 

The determination of iodide with ion-selective electrodes is possible with commercial sensors often based on ion conducting Ag2S—Agl solid membranes [57]. A PVC membrane-based sensor employing a silver complex with thiourea derivatives has been reported by El Aamrani et al. [202]. Interference from thiocyanate and bromide was investigated and a limit of detection in the nanomolar range was determined. A study assessing the performance... 

Ion-Selective Electrodes based on Bis-Thiourea Receptors. Bis-thiourea derivatives 14, 15, and 17, which have a good membrane solubility, sufficient lipophilicity to prevent leaching into the aqueous sample solution, and a low tendency for self-aggregation in nonpolar solvents, were incorporated into PVC matrix liquid membranes for ISEs. While membrane electrodes based on the dibutyl derivative 14 gave a phosphate response almost identical to that of a conventional anion-exchanger electrode, a membrane electrode based on the phenyl-substituted bis-thiourea 15 exhibited a slightly improved phosphate response, which seems to be the result of improved complexation of phosphate in the sensor membrane. 

These hosts include simple anion sensor systems containing urea, thiourea, amine, amide, alcohol, and pyrrole groups linked to chromophores. Chro-mophores used in this type of chromogenic anion sensors are mainly organic dyes such as azobenzene, nitrobenzene, indoaniline, and anthraquinone or... 

Besides urea and thiourea, amide groups can also form effective chromogenic anion sensors. Jurczak and coworkers [14] have demonstrated the use of amide groups containing nitrophenyl-macrocycle 3 as a selective colori-... 

Acetylcholineesterase and choline oxidase Au foil was treated with cystamine to produce a base layer of ami-nothiolate units, was derivatized by reaction of the amino group and disodium-4,4 -diisothiocyanato-trans-stilbene-2,2 -disulfonate. Enzymes were immobilized at the isothiocyanate group via thiourea link. The bifunctional sensor for ACh was prepared by stepwise immobilization of four layers of the enzyme ChO and three layers of AChE. Choline generated was detected amperometircally with the use of 2,6-dichloro-phenolindophenol as a mediator in solution. Electrical communication between the enzyme and the electrode is achieved either by the use of ferrocenecar-boxylic acid as mediator in the assay buffer or by immobilization of [(ferrocenyl methyl)amino] hexa-noic acid on the enzyme layer. [92]... 

Gunnlaugsson and co-workers have studied several receptors containing a thiourea group attached to an anthracene moiety [33]. These compounds were designed to behave as fluorescent PET (photo-induced electron transfer) sensors for the detection of anionic species. Proton NMR titration experiments, conducted in DMSO-de, confirmed that the anions bind to the... 

In addition to reaction catalysts, a number of quinolines were described with valuable chemo-sensing properties. Even a simple quinolone, such as that shown in Scheme 1, can be used as a method for cyanide detection in aqueous environments (14TL1052).This quinoline-derived probe with an aldehyde forms a cyanohydrin with strong fluorescence. Another quinoline chemosensor, a quinoline tripodal thiourea, selectively binds with fluoride and no other halogens (14TL1467). A thioamide-based sensor with both... 

MPc modified CPFs have been employed by several researchers for the analysis of thiols. Carbon paste electrodes incorporating OMo (OH)Pc catalyzed the oxidation of cysteine with a considerable reduction in overpotential Table 7.2. The oxidation of cysteine was mediated by Mo Pc species. CoPc modified CPMF was used as a sensor for analysis of cysteine and glutathionine in urine using electrophoresis " , with detection limits of 3.1 x 10 and 3.0x10 M, respectively. CoPc modified CPE was employed for the potentiometric oxidation of 2-mercaptobenzimidazole and 2-mercaptobenzothiazole . Low peak potentials of 0.45 V for the former and 0.27 V for the latter were obtained . A detection limit of 5 x 10 M was obtained. CPFs modified with CoPc showed catalytic activity for the determination of thiocarbonyl compounds (thiourea, thioac-etamide, thiobenzamide, and dithiooxamide) " and the oxidation of thioglyconic acid " . The latter occurred via a two step process, which leads to the formation of the dimer of the thiol " . A carbon paste electrode constructed from NiTSPc immobilized on silica gel modified with 1102 catalyzed the oxidation of cysteine " . The immobilization caused the increase in the monomeric form of the catalysts. 

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