Langmuir-Blodgett films of alkylpyridines as metal ion sensors

Caminati, Gabriella; Margheri, E.; Gabrielli, G.

doi:10.1016/0040-6090(94)90597-5

Cited by 22 publications

(7 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In principle, the metal ions can be incorporated into the monolayer film in two ways. First, by means of salt or complex formation by the amphiphile from the subphase wherein the metal ions are dissolved, and second the metals could be bound to the amphiphile before spreading the formed salt or the metal complex at the air−water interface. , Dithiooxamides, , pyridines, , porphyrines, and phthalocyanines , are often used as ligands for complex formation with metal ions. When crown ethers and imidazoles are used as ligand units in amphiphiles, even at very low subphase concentrations (10 -6 M), metal ions are incorporated into the floating monolayer at the air−water interface, as was shown by Lednev and Petty and van Esch et al Also, metal ions could be incorporated into floating polymer monolayers with an amphiphilic character that have ligand groups such as pyridine, bipyridine, or crown ethers …”

Section: Introductionmentioning

confidence: 99%

Langmuir−Blodgett Films of Metal Complexes of 4-(10,12-Pentacosadiynamidomethyl)pyridine: A Structural Investigation

et al. 1998

View full text Add to dashboard Cite

Complex formation between 4-(10,12-pentacosadiynamidomethyl)pyridine and metal ions in the subphase results in stable Langmuir monolayers up to surface pressures of 35 mN m -1 . Electron microscopy pictures show a flat monomer monolayer before polymerization and a polymer monolayer exhibiting a more striated structure after polymerization. Multilayers of the amphiphile can only be built up after complexation with metal ions. X-ray photoelectron spectroscopy (XPS) measurements definitely confirm the presence of metal ions in the multilayers, and the molar ratio between metal and amphiphile is derived from the spectra. These multilayers are further characterized by means of small-angle X-ray reflection measurements and Fourier transform infrared (FT-IR) spectroscopy, which show that the amphiphile has a large tilt angle (R) with respect to the surface normal. The multilayers are polymerized by means of UV irradiation, and UV-vis spectroscopy is used to study the polymerization process. The structural changes during polymerization are deduced from small-angle X-ray reflection measurements and FT-IR spectroscopy. In all cases, the bilayer spacing decreases during the polymerization process, whereas in some cases the regular plane of the all-trans conformation of the alkyl chains is converted to an irregular one containing gauche conformations. For multilayers built up from a CuCl2-containing subphase, the whole distinct layer structure is destroyed during the polymerization process.

show abstract

Section: Introductionmentioning

confidence: 99%

Langmuir−Blodgett Films of Metal Complexes of 4-(10,12-Pentacosadiynamidomethyl)pyridine: A Structural Investigation

et al. 1998

View full text Add to dashboard Cite

show abstract

“…In addition, since they are generally prepared by soaking paper in the signaling reagent, leakage of reagent is facile, and hence reliability and sensitivity of detection are poor. Firm fixation of colorimetric and fluorometric reagents for metals on solid substrates has been attempted by incorporation into PVC‐based liquid membranes,1 covalent anchoring with cross‐linked copolymers,2 and layer‐by‐layer accumulation methods such as Langmuir–Blodgett films3, 4 and alternate deposition of oppositely charged polyelectrolytes 5. 6 A wealth of information on optical sensors and probes for simple determination of heavy metals has been reviewed 7.…”

Section: Preparation Conditions and Properties Of Nanosized Dyesmentioning

confidence: 99%

Test Strips for Heavy‐Metal Ions Fabricated from Nanosized Dye Compounds

et al. 2006

View full text Add to dashboard Cite

Analytical test strips for heavy-metal ions can provide simple and convenient procedures for on-site analysis and daily monitoring of water quality without using costly instruments. However, since the standard limit values of heavy metals in the environment and drinking water are remarkably low (ppb level), the detection limits of commercial test strips (ppm level) are insufficient to satisfy the required criteria. In addition, since they are generally prepared by soaking paper in the signaling reagent, leakage of reagent is facile, and hence reliability and sensitivity of detection are poor. Firm fixation of colorimetric and fluorometric reagents for metals on solid substrates has been attempted by incorporation into PVCbased liquid membranes, [1] covalent anchoring with crosslinked copolymers, [2] and layer-by-layer accumulation methods such as Langmuir-Blodgett films [3,4] and alternate deposition of oppositely charged polyelectrolytes. [5,6] A wealth of information on optical sensors and probes for simple determination of heavy metals has been reviewed. [7] However, drawbacks include complicated synthetic procedures, insufficient sensitivity, requirements for auxiliary additives, and difficulty in controlling the concentration of the reagent and its uniformity. Hence, we sought a simple procedure for firm and uniform coating of signaling reagents on an appropriate substrate without any additional matrix.Recently, a simple and versatile process known as the "reprecipitation method" was proposed for the preparation of aqueous dispersions of organic nanoparticles.[8] The process involves injection of a water-miscible organic solution into water with vigorous stirring. We found that various organic nanoparticles can be uniformly coated onto a membrane filter (cellulose ester type) to form a thin layer simply by filtration of the nanoparticle dispersion. We attempted to apply this simple procedure to the fabrication of analytical test strips from a selection of signaling reagents. We examined popular indicator dyes having an aromatic conjugated system: dithizone (Dith), 1-(2-thiazolylazo)-2-naphthol (TAN), 1-(2-pyridylazo)-2-naphthol (PAN), tetraphenylporphin (TPP), and bathophenanthroline (Bathophen).Optimized preparative conditions for aqueous dispersions of the indicator dyes are listed in Table 1. Water-miscible acetone and THF were used for dissolution of the dyes. The pH of the aqueous phase was controlled to maintain electroneutrality of the dye species by considering the pK a values of the respective compounds. Smaller particles are formed with increasing temperature of the aqueous phase and with decreasing dye concentration in the organic phase.[9] Figure 1 shows scanning electron microscopy (SEM) images of TPP nanoparticles and PAN nanofibers. Round particles (50-100 nm) were mainly formed from TPP and Bathophen. In contrast, fibrous products were formed in the case of PAN, TAN, and Dith. These dyes commonly have dissociative protons capable of forming intermolecular hydrogen bonds which assist formation...

show abstract

“…The study of the interactions of these supramolecular structures with metal ions is particularly important to develop new materials in the field of chemical sensors by means of the Langmuir-Blodgett technique. In fact, the investigation of the interfacial eomplexation process eventually leads to the realization of fiber optic sensors for the (*) Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4-8, 1994. detection of transition metals in polluted waters or toxic gases [2,3]. As a part of a systematic study on the complexation properties of Langmuir monolayers we report the results obtained using as amphiphilic molecule a double-chain dithiocarbamate.…”

Section: -Introductionmentioning

confidence: 99%

Interactions of metal ions with monolayers and with Langmuir-Blodgett films

et al. 1994

View full text Add to dashboard Cite

(ricevuto il 28 Ottobre 1994)Summary. --Oriented systems such as monolayers and Langmuir-Blodgett multilayers constitute supramolecular structures appropriate for ion detection. In fact, they are sensitive to small quantities of ions since they have specifically oriented ligand head groups that can easily combine with the ions to be detected in solution. We investigated monolayers of dioctadecyldithiocarbamate (DODTC) specifically synthesized and we studied the interactions of the monolayers with transition metal ions such as Ni 2+ dissolved in the subphase. The spreading isotherms, the surface potential-area isotherms and the spectroscopic measurements (UV-Vis absorption and ESCA spectroscopy) show that the metal ions can combine with the DODTC monolayers. The present findings show that it is possible to employ these systems to build chemical sensors for transition metal ions. PACS 68.10 -Fluid surfaces and fluid-fluid interfaces. PACS 01.30.Cc -Conference proceedings.

show abstract

Langmuir-Blodgett films of alkylpyridines as metal ion sensors

Cited by 22 publications

References 1 publication

Langmuir−Blodgett Films of Metal Complexes of 4-(10,12-Pentacosadiynamidomethyl)pyridine: A Structural Investigation

Langmuir−Blodgett Films of Metal Complexes of 4-(10,12-Pentacosadiynamidomethyl)pyridine: A Structural Investigation

Test Strips for Heavy‐Metal Ions Fabricated from Nanosized Dye Compounds

Interactions of metal ions with monolayers and with Langmuir-Blodgett films

Contact Info

Product

Resources

About