Beatriz Cabezón

Triazolephthalocyanines: synthesis, supramolecular organization and physical properties

Abstract Different synthetic paths for obtaining triazolephthalocyanines (Tpcs), a new kind of A3B-type phthalocyanine analogues, are discussed in this paper. An overlook of the structural and characterization features of these compounds is also given. Finally, it is shown why Tpcs are promising targets for the construction of organic molecular materials: they have not only interesting conducting and nonlinear optical properties, but also the capability to be organized in condensed phases such as liquid-crystals and LB-films.

Expanded phthalocyanine analogues: synthesis and characterization of new triazole-derived annulenes containing six heterocyclic subunits.

A series of heteroannulenes 3a-f containing four subunits of isoindole, two 1,2,4-triazole moieties, and six aza bridges have been synthesized by dimerization of the corresponding metallated, three-unit intermediates 5a-f. All these 28 pi-electron triazolephthalocyanine derivatives coordinate two metal ions within their central cavity and are the first examples of expanded heterophthalocyanines. Spectroscopic properties of these macrocycles show evidence for extended conjugation and antiaromaticity. The nature of the metal ions plays a definite role in the electronic properties of these derivatives.

Synthesis of Crowned Triazolephthalocyanines

The synthesis of triazolephthalocyanines bearing crown ether and aza-crown ether substituents is described. Different substituents have been introduced on the nitrogen atom of the aza-crown moiety to improve the solubility and the intrinsic amphiphilic character of these macrocycles. The crowned triazolephthalocyanines described have been prepared by a statistical procedure, and also by different variations of a stepwise method. Preliminary studies of the aggregation properties of one representative of this new family of compounds have also been carried out. An exhaustive study of the synthesis of the corresponding dicyano derivative precursors of the triazolephthalocyanines is displayed. Two different approaches have been used for this goal: The first one inserts the cyano groups prior to the synthesis of the crown ether moiety, while the second one builds the crown ether part of the molecule in advance of the cyanation process. The incompatibility of the Rosemund-von-Braun cyanation conditions and the presence of nitrogen atoms in the molecule is the main difficulty of the synthesis of these precursors.

Metallotriazolephthalocyanines as potential molecular subunits for the preparation of nonlinear optical active systems

Abstract A series of triazolephthalocyaninatonickel (II), -copper (II), and -cobalt (II) complexes have been prepared and characterized. Soluble compounds show favourable characteristics for the preparation of Langmuir-Blodgett films. Preliminary studies of their NLO properties in solution have been made.

Semiconducting Langmuir-Blodgett films of new triazolephthalocyanines

Abstract Semiconducting Langmuir-Blodgett films of Phthalocyanine analogues 1 and 2 have been prepared. These compounds orient vertically on the Langmuir and Langmuir-Blodgett layers. Six layer LB films show a conductivity around 10 −4 Ω −1 cm −1 . Resistance temperature dependence experiments have been performed. The resistance behaviour of the samples is rational with a semiconductor.

Organization of triazolephthalocyanines in Langmuir-Blodgett films

Langmuir monolayers were prepared using a new class of non-centrosymmetric macrocycles, the triazolephthalocyanines, differently substituted with aliphatic chains and/or thiophene subunits. Different monolayer behaviour and film deposition have been observed among the different macrocycles. Compounds substituted with two long aliphatic chains on the isoindole ring opposite to the triazole unit have shown the best monolayer behaviour. Stable monolayers were successfully transferred onto CaF 2 substrates which had been made hydrophobic. The Langmuir–Blodgett films were characterized by IR and UV–VIS linear dichroism. In-plane orientation of some of the macrocycles was observed when nickel(ii) acetate was added to the aqueous subphase.

Computational study of the geometry and electronic structure of triazolephthalocyanines

Semiempirical molecular orbital methods were used to simulate the molecular structure and electronic spectra of a series of triazolephthalocyanines (Tpcs). All molecular studies are in agreement with an aromatic macrocycle where a hypothetical substitution on both triazole and meso nitrogens of the core causes a partial breakdown in the Goutermans four level model. Minor effects are predicted for the substitution in the isoindole subunit. Comparison between the experimental and theoretical UV–VIS spectra of different metal substituted triazolephthalocyanines is also made.

Iron-and rutheniumtriazolehemiporphyrazines as molecular subunits for the preparation of semiconducting polymers

The synthesis of iron (II) triazolehemiporphyrazinates and their polymerization with different bridging ligands have been accomplished. Studies on the electrical conductivity of the undoped and doped polymers have been carried out. The studies have been extended to ruthenium derivatives.

Synthesis, magnetic and mass spectrometric studies on dinuclear complexes based on Schiff-base triazolic ligands

A series of dinuclear complexes of NiII, CoII and CuII have been prepared by template 1 : 2 condensation of 3,5-diacetyl-1,2,4-triazole and the corresponding aniline in the presence of 1 equivalent of lithium hydroxide and the corresponding metal(II) salt. The dinuclear nature of the nickel and cobalt compounds have been demonstrated by FAB mass spectrometry and magnetic measurements, which indicate the presence of antiferromagnetic exchange interactions.

NEW POLYAZA MACROBICYCLIC CRYPTANDS BASED ON 1,2,4-TRIAZOLE LIGANDS AND THEIR CU(I), AG(I), CU(II) AND NI(II) COMPLEXES

Abstract New polytopic cryptands 2–4 containing 1,2,4-triazole subunits have been synthesized by [2+3] condensation of the corresponding acyltriazole 5 and tris(2-aminoethyl)amine (Tren) in excellent yield; 2 and 3 gave dinuclear Ag(I) and trinuclear Cu(I) cryptates, and 4 yielded trinuclear Ni(II) and Cu(II) complexes in alkaline media. The nature of the complexes has been established by LSIMS and MALDI-TOF mass spectrometry.