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T Torres

Publications and source records attributed to T Torres.

At least 19 recordsLinked to original sources
PubMed2001

Thiadiazole-derived expanded heteroazaporphyrinoids.

[structure: see text] Heteroannulenes 1 and 3 containing three subunits of isoindole or pyrrole, respectively, three 1,3,4-thiadiazole moieties, and six aza-bridges have been synthesized by reaction of the corresponding diiminoisoindoline or diiminopyrroline with 2,5-diamino-1,3,4-thiadiazole. These conjugated nonaromatic 30 pi-electron macrocycles coordinate three metal ions within their central cavity and constitute one of the rare examples of expanded heteroazaporphyrinoids.

Journal Article↗
PubMed2001

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.

Aza Compounds↗
PubMed2001

Synthesis of nickel(II) triazolenaphthalocyanine and related macrocycles.

The synthesis of novel monbenzotriazolephthalocyanines (3-6), low-symmetry phthalocyanine analogues, is described for the first time using a novel and simple stepwise strategy which involves the use of substituted naphthalodinitriles 8-11 and appropriately substituted three-unit compounds such as 7. Belonging to the same family, compound 1, which we have called triazolenaphthalocyanine, has been prepared by a statistical method from compound 2 and 3,5-diamino-1,2,4-triazole. Compound 1 shows a bathochromic shift of the Q-band in UV-vis spectrum due to the fusing of benzene rings to the triazolephthalocyanine core.

Journal Article↗
PubMed2000

Copper-mediated synthesis of phthalocyanino-fused Dehydro

Cyclooligomeric phthalocyanines with the special feature of having a dehydroannulene core are described. Compounds 4a,b and 5a,b were prepared by an oxidative coupling mediated by copper from the corresponding diethynyl unsymmetrically substituted phthalocyanines 8a,b, which are easily accessible from the corresponding diiodo compounds 6a,b by a palladium-copper-catalyzed coupling. Appropriate conditions to selectively form cyclodimers and cyclotrimers using Glaser and Eglinton methodologies have been attempted. In this way, two compounds, 4a and 5b, each representative of a kind of oligomers, could be appropriately isolated and characterized by MALDI-MS. The UV-vis spectra of compounds 4a and 5b show a split Q-band shifted to the red with respect to the corresponding precursor 8a,b. This can be interpreted, in light of previous results, as a consequence of intramolecular electronic coupling between the Pc subunits. Extensive formation of aggregates in chloroform can be also inferred from the spectra. No significant differences could be observed in the spectra by comparison with that of the open-chain analogue 11, most probably due to a saturation phenomenon of the optical properties already pointed out in the literature for other alkynyl-linked open-chain dimers.

Journal Article↗
PubMed2000

Synthesis and electrochemical properties of phthalocyanine--fullerene hybrids

Phthalocyanines linked to C60 have been synthesized by two general strategies. One of them involves the addition of an azomethine ylide prepared in situ from a formyl phthalocyanine to C60, and the other one involves a statistical condensation of two substituted phthalonitriles, one of them bearing the C60 moiety covalently attached. These new phthalocyanine-fullerene dyads have been studied by cyclic voltammetry and Osteryoung square wave voltammetry, and inter- and intramolecular electronic interactions between the two electroactive subunits have been demonstrated.

Journal Article↗
PubMed2000

Synthesis of unsymmetrically substituted subphthalocyanines

A series of new unsymmetrically substituted subphthalocyanines containing iodo or octylthioether substituents on the outer aromatic rings have been synthesized. The statistical reaction of one equivalent of 1,2-dicyano-3-iodobenzene whether with two equivalents of 1,2-dicyano-4-octylthiobenzene or with two equivalents of 1,2dicyano-4,5-dioctylthiobenzene in the presence of boron trichloride in 1-chloronaphthalene yielded in both cases all the possible expected unsymmetrically substituted subphthalocyanines, which were separated by column chromatography on silica gel. All compounds were identified by FAB mass spectrometry and then characterized by HR-LSIMS spectrometry. The unambiguous characterization of each constitutional isomer was made possible by careful examination of the symmetry environment experienced by each proton on their 1H-NMR spectra.

Journal Article↗
PubMed2000

Synthesis of novel push-pull unsymmetrically substituted alkynyl phthalocyanines

Two families of "push-pull" phthalocyanines 1-3 having an unusually strong dipole moment have been prepared. The syntheses of unsymmetrically substituted phthalocyanines 1a,b and 2 bearing one or two electron-withdrawing 4-nitrophenylethynyl moieties, respectively, and six alkoxy substituents were performed by combination of a zinc or nickel templated cyclotetramerization and cross-coupling palladium mediated methodologies. In a similar way, the "push-pull" compounds 3a,b having a reversal substitution pattern, characterized by the presence of one electron-donor 4-(dimethylamino)phenylethynyl unit and six strong acceptor alkylsulfonyl substituents were prepared. The compounds show very large second-order nonlinear optical responses.

Journal Article↗
PubMed2000

Photophysical properties of neutral and cationic tetrapyridinoporphyrazines.

We describe the synthesis and photophysical properties of a series of neutral and cationic 3,4-tetrapyridinoporphyrazines, potential lead photosensitizers for photodynamic inactivation of bacteria. Tetracationic TPyPzs exist essentially as monomers in aqueous systems, but the presence of trialkylated compounds due to incomplete quaternization of the outer nitrogen atoms induces severe aggregation. The absorption, fluorescence, triplet, and singlet oxygen quantum yields for both the neutral and cationic compounds are comparable to those of the related phthalocyanines.

Cations↗
PubMed1999

Infusion phlebitis in post-operative patients: when and why.

BACKGROUND: The most common complication of intravenous therapy is infusion phlebitis. This study was done to prospectively assess its frequency in a series of consecutive patients who will undergo surgery, and to identify which variables may predict an increased risk for phlebitis. PATIENTS AND METHODS: 400 consecutive patients who will undergo surgery in a general surgery department were included. Only the first catheter, inserted the day before surgery, was taken into account. Eighteen variables (from the infusion, the catheter and from the patient) were prospectively evaluated for their contribution to the occurrence of phlebitis. RESULTS: 60/400 patients (15%) developed phlebitis, and most of them needed insertion of a further catheter. The univariate analysis showed that patients who developed phlebitis were older, and their pre-operative levels of both blood haemoglobin and neutrophil cound were significantly higher than those in patients who did not develop phlebitis. However, the multivariate analysis only confirmed the association with blood haemoglobin levels: the risk of phlebitis sharply increased in the patients with the highest haemoglobin levels. As to the influence of time on phlebitis development, there was a significant decrease in the day-specific risk, from the 5th day on. COMMENTS: In our series, blood haemoglobin levels were found to be the only variable associated to a higher risk of phlebitis. Besides, in contrast with the recommendations by the Centers for Disease Control, no significant increase in the day-specific risk of phlebitis was found. Thus, a guideline to select the type of catheter to be inserted in an individual patient is suggested.

Adolescent↗
PubMed1998

Environmental health sciences education--a tool for achieving environmental equity and protecting children.

Children are highly susceptible to deleterious effects of environmental toxins. Those who live in underserved communities may be particularly at risk because environmental pollution has been found to be disproportionately distributed among communities. Mounting evidence suggests that asthma rates are rising and that this disease can be caused or aggravated by air pollution. Although ambient air quality has generally improved, these improvements have not reached minority communities in equal proportions. This and other data has fueled the concept of environmental justice or environmental equity, which has led to community activism and government actions. One possible example of environmental inequity and its consequences is the Hunt's Point community, in the South Bronx, New York. This community experiences a high pollution burden with the siting of facilities that emit hazardous wastes into the air. Our approach to this problem has been the formation of mechanisms for bidirectional communication between community residents, government entities, and academic institutions such as Mount Sinai Medical Center. As a result of this experience, we believe that the key to achieving environmental health, especially in communities of color where many children are at risk, is to empower residents to take charge of their environment by providing relevant educational opportunities. Strategies for environmental health education include multitiered training approaches that include community residents, parent education, direct children education, and community education through professional counselors and train-the-trainer approaches. We propose that academic researchers must use community residents not just as subjects of our studies, but to increase our mutual understanding of environmental health, resulting in active participation of community members in research design, data collection, analysis, and dissemination of results in order to make intervention strategies more effective.

Child↗
PubMed1998

Texturing and polishing. The final attempt at value control.

This article reviews methods for developing surface texture and controlling the luster of ceramic restorations. The authors discuss the characteristics of embryology and age, and profile characteristics of teeth that are vital in creating natural, anatomic restorations. A technique is proposed to enhance the scattering of light and the amount of luster desired in the restoration. The authors recommend hand polishing over autoglazing as a more efficient way to obtain the desired luster. The combination of developing the proper texture and luster is important for the overall value of the restoration.

Adult↗
PubMed1990

Expression and translocation of cloned human estrogen receptor in the Xenopus oocyte does not induce expression of the endogenous oocyte vitellogenin genes.

Estrogen-receptor complex activates the genes coding for the egg yolk protein precursor vitellogenin in hepatocytes of oviparous vertebrates, while oocyte vitellogenin genes are unresponsive to the hormone. Localization of [3H]steroid hormones (estradiol, progesterone, testosterone, and dexamethasone) was assayed in 10% trichloroacetic acid-precipitated dissected Xenopus oocytes (germinal vesicle vs. the rest of the oocyte). Whether hormones were introduced by incubation in the medium surrounding the oocytes or by injection of an equivalent amount into the oocyte cytoplasm, all hormones partitioned into the nucleus at equivalent levels (approximately 5%), reflecting that portion of the oocyte volume occupied by its nucleus. Therefore, intracellular receptors for these hormones were not detectable. Subsequently, we introduced a species-heterologous estrogen receptor into the Xenopus oocyte via a recombinant plasmid containing the coding sequence for the human estrogen receptor (HER) housed in a vector that ensures highly efficient transcription and translation of inserted sequences. HER synthesis was directed from injected plasmid (2 ng/oocyte germinal vesicle) as shown by [35S]methionine incorporation into newly synthesized proteins; however, vitellogenin was not synthesized under these conditions. When HER plasmid-injected oocytes were incubated in [3H]estradiol, they translocated to the nucleus 38% of the radiolabeled estradiol taken up by the cells, compared to 5% nuclear localization for vector-injected controls. Therefore, although the oocyte can readily transcribe and translate HER sequences as well as appropriately partition the completed protein in the nuclear compartment, the endogenous, potentially estrogen-responsive vitellogenin genes of the oocyte are not expressed.

Animals↗