The optical characterization of metal-mediated aggregation behaviour of amphiphilic Zn(ii) phthalocyanines.

Ag(+) mediated aggregation behaviour of two different amphiphilic zinc phthalocyanines (Zn-Pcs) (symmetric and asymmetric) has been investigated in solution, at the air-water interface and in Langmuir-Blodgett (LB) films transferred onto glass substrates. A 4 : 1 ([Ag(+)]/[Pc]) complexation was observed for both symmetric and asymmetric Zn-Pcs at high [Ag(+)] concentrations which led to the formation of H-aggregates in solution. At the air-water interface, both symmetric and asymmetric Zn-Pcs showed a tilted, edge-on orientation in columnar stacks. Addition of Ag(+) to the subphase enhanced the order in the monolayers. LB films on glass substrates showed a split Q-band indicating the presence of "herring-bone" type aggregation consisting of both H- and J-aggregates. For LB films deposited from a Ag(+) containing subphase, a shoulder appeared in the absorption spectra at longer wavelengths which indicates that the fraction of J-aggregates was enhanced by Ag(+) in LB films. The molecular orientation in LB films was investigated by polarized absorption spectroscopy and a tilt angle was calculated to be 49° with the substrate normal for symmetric and 74.6° for the asymmetric Zn-Pc. The presence of Ag(+) cations in the subphase decreased the tilt angles slightly by 4-5°. These results indicate that Ag(+) induced the aggregation of Zn-Pcs and acted as a linker between Pc molecules in the ultrathin films of both symmetric and asymmetric Zn-Pcs. These results are important in inducing J-aggregates for the fabrication of molecular devices based on phthalocyanine thin films.

Use of the electrochromic behaviour of lanthanide phthalocyanine films for nicotinamide adenine dinucleotide detection.

Electrochromic properties of spun films of bis[octakis(hexylthio)phthalocyaninato] dysprosium(III) were investigated for determining nicotinamide adenine dinucleotide hydride (NADH) in water solutions. A spin-coated film deposited on indium tin oxide electrode displays only one redox couple (at E1/2=0.78V). The films of [(C6H13S)8Pc]2Dy were modified chemically or electrochemically for the detection of reduced NADH in water solution. The modified film in the oxidized ([(C6H13S)8Pc]2Dy)+ form is believed to be reduced to its neutral form on interaction with NADH.

Dielectric spectroscopy analysis in employing liquid crystal phthalonitrile derivative in nematic liquid crystals.

Dielectric anizotropy and relaxation properties of 2,3-dicyano-1,4-di[3,4,5-tri(dodecyloxy)phenylcarbonyloxy] benzene (DCDPB)-doped E7 and E7 liquid crystal have been investigated by the dielectric spectroscopy method. Dielectric anisotropy property of the LCs changes from the positive type to negative type. Dielectric relaxation properties suggest that LCs exhibit a monodispersive dielectric property. The relaxation frequency of E7 and E7/DCDPB liquid crystals was calculated by means of Cole-Cole plots. Consequently, DCDPB dopant changes the dielectric anizotropy and relaxation parameters of E7 LC.

The structure-inhibitory activity relationships study in a series of cyclooxygenase-2 inhibitors: a combined electronic-topological and neural networks approach.

Structure-activity relationships study was performed for a few series of cyclooxygenase-2 (COX-2) inhibitors by using the Electronic-Topological Method combined with Neural Networks (ETM-NN). Specific molecular fragments were found for active compounds ('activity features') from both series by the ETM application. After this, a system of prognosis was developed as the result of training Kohonen's self-organizing maps (SOM) by the fragments. From the detailed analysis of all compounds under study, requirements necessary for a compound to be COX-2 inhibitor were formulated. The analysis showed that any requirements violation for a molecule resulted in a considerable decrease or even complete loss of its activity. The found activity features identified correctly different marketed drugs and new compounds that had passed pre-clinical and clinical trials; this fact confirms the workability of the system developed for the COX-2 inhibitory activity prediction.

Electronic-topological study of the structure-activity relationships in a series of piperidine morphinomimetics.

Structure-activity relationships (SAR) are studied in the series of 4,4-disubstituted piperidine morphinomimetics (42 compounds) by means of the Electronic-Topological Method (ETM). In the frameworks of this approach, its input data were taken as the results of conformational and quantum-mechanical calculations. These calculations had been carried out for all compounds from the series under study, taking into account their neutral and protonated by the nitrogen of piperidine cycle forms. The ETM application resulted in a set of pharmacophores and anti-pharmacophores, which formed a basis of a system used to predict analgesic activity. First of all, the system was tested on known analgesics. Testing has shown a good agreement with the experimental data. Then, the system was applied to a few compounds with similar structures but unknown activity. The results of the study could be used for computer screening and design of novel compounds with analgesics properties as new potential drugs.

Electronic-topological study of structurally diverse cyclooxygenase-2 inhibitors.

A large series of cyclooxygenase-2 (COX-2) inhibitors with diverse skeletons were investigated by means of the Electronic-Topological Method. A system for the COX-2 inhibitor activity prognostication was built with 6 pharmacophores and 6 anti-pharmacophores. The forecasting ability of the system was also tested on different structures, which differ from those that characterize the series studied.

Investigations and application in piezoelectric phenol sensor of Langmuir-Schäfer films of a copper phthalocyanine derivative functionalized with bulky substituents.

An octa-substituted copper phthalocyanine was dissolved in chloroform and spread on ultrapure water subphase in a Langmuir trough. The floating films were characterized at the air-water interface by the Langmuir isotherm, Brewster angle microscopy, and UV-Vis reflection spectroscopy and transferred by Langmuir-Schäfer technique on a silicon substrate, and thickness, refractive index, and extinction coefficient of the phthalocyanine derivative thin film were calculated by means of spectroscopic ellipsometry. A different number of layers were deposited using Langmuir-Schäfer method onto QCM crystals, and the active layers were tested as sensors for the detection of phenols in aqueous solution. The piezoelectric sensor response, totally reversible, is influenced by the number of transferred layers and by the nature of the substituent; on the contrary, the pK(a) value of the injected analytes slightly affects the device performances. Repeatability of the sensor responses was tested, and the frequency variation appears unchanged at least for 100 days.

Orthogonally bifunctionalised polyacrylamide nanoparticles: a support for the assembly of multifunctional nanodevices.

Polyacrylamide nanoparticles bearing two orthogonal reactive functionalities were prepared by reverse microemulsion polymerisation. Water-soluble photosensitisers and peptide or carbohydrate moieties were sequentially attached to the new nanospecies by orthogonal conjugations based on copper-catalysed azide-alkyne cycloaddition and isothiocyanate chemistry.

Synthesis, structure, spectroscopic properties, and magnetic properties of an octakis(alkylthio)-substituted lutetium(III) bisphthalocyanine.

The synthesis of a new sandwich lutetium(III) bisphthalocyanine substituted with hexylthio groups (1), [(C6H1)S)8-Pc]2Lu, is described. The compound is very soluble in most common organic solvents and has been fully characterized (elemental analysis, IR, 1H and 13C NMR, UV-vis spectroscopy, mass spectrometry). The chemically oxidized and reduced forms have been formed and characterized. The crystal structure of the compound (1) has been determined by X-ray diffraction on a single crystal. It crystallizes in the monoclinic space group C2/c with a = 31.558(2) A, b = 32.755(2) A, c = 20.489(1) A, beta = 127.119(1) degrees, and Z = 4. The temperature dependence of the magnetic susceptibility, measured on polycrystalline samples and in the range 6-300 K, is in agreement with one unpaired electron per molecular unit as found for the unsubstituted derivative. The magnetic results can be modeled assuming one-dimensional chain of spin S = 1/2 with g = 2.04 and an antiferromagnetic coupling (J = -11.83 cm(-1), H = -2JSigmaSiSj).