Publications by authors named "Augusto C Tome"

Antimicrobial resistance remains an enduring global health issue, manifested when microorganisms, such as bacteria, lack responsiveness to antimicrobial treatments. Photodynamic inactivation (PDI) of microorganisms arises as a noninvasive, nontoxic, and repeatable alternative for the inactivation of a broad range of pathogens. So, this study reports the synthesis, structural characterization, and photophysical properties of a new tetra-β-substituted pyridinium-pyrazolyl zinc(II) phthalocyanine (ZnPc ) that was compared with two previously described pyridinium-pyrazolyl ZnPcs and .

View Article and Find Full Text PDF

Diketopyrrolopyrroles (DPPs) are a versatile group of dyes and pigments with valuable optoelectronic properties. In this work we report the synthesis of highly fluorescent DPP derivatives through straightforward nucleophilic aromatic substitution reactions with thiols and phenols. These nucleophilic substitutions occur at room temperature and manifest a remarkable selectivity for the 4-position of the pentafluorophenyl groups.

View Article and Find Full Text PDF

New β-amino-substituted porphyrin derivatives bearing carboxy groups were synthesized and their performance as sensitizers in dye-sensitized solar cells (DSSC) was evaluated. The new compounds were obtained in good yields (63-74%) through nucleophilic aromatic substitution reactions with 3-sulfanyl- and 4-sulfanylbenzoic acids. Although the electrochemical studies indicated suitable HOMO and LUMO energy levels for use in DSSC, the devices fabricated with these compounds revealed a low power conversion efficiency (PCE) that is primarily due to the low open-circuit voltage (V) and short-circuit current density (J) values.

View Article and Find Full Text PDF

In the present work, several coumarin-3-carboxamides with different azacrown ether moieties were designed and tested as potential luminescent sensors for metal ions. The derivative containing a 1-aza-15-crown-5 as a metal chelating group was found to yield the strongest response for Ca and Pb, exhibiting an eight- and nine-fold emission increase, respectively, while other cations induced no changes in the optical properties of the chemosensor molecule. Job's plots revealed a 1:1 binding stoichiometry, with association constants of 4.

View Article and Find Full Text PDF

Access to clean water is increasingly challenging worldwide due to human activities and climate change. Wastewater treatment and utilization offer a promising solution by reducing the reliance on pure underground water. However, it is crucial to develop efficient and sustainable methods for wastewater purification.

View Article and Find Full Text PDF

In this work we pursued research involving the microwave-assisted -alkylation of a NH pyrrolidine-fused chlorin with methyl 4-(bromomethyl) benzoate and subsequent ester hydrolysis as a straightforward strategy to obtain carboxylic acid functionality in the pyrrolidine-fused chlorin, as a single reaction product. We studied the reaction's scope by extending the -alkylation of the free-base chlorin and its corresponding Zn(II) complex to other alkyl halides, including 1,4-diiodobutane, -(2-bromoethyl)phthalimide, and 2-bromoethanaminium bromide. In addition, two new chlorin-dansyl dyads were synthesized by reacting dansyl chloride with the 2-aminoethyl pyrrolidine-fused chlorin (dyad ) and NH pyrrolidine-fused chlorin (dyad ).

View Article and Find Full Text PDF

Antimicrobial photodynamic therapy (aPDT) has been explored as an innovative therapeutic approach because it can be used to inactivate a variety of microbial forms (vegetative forms and spores) without causing significant damage to host tissues, and without the development of resistance to the photosensitization process. This study assesses the photodynamic antifungal/sporicidal activity of tetra- and octasubstituted phthalocyanine (Pc) dyes with ammonium groups. Tetra- and octasubstituted zinc(II) phthalocyanines ( and ) were prepared and tested as photosensitizers (PSs) on conidia.

View Article and Find Full Text PDF

The search for accurate and sensitive methods to detect chemical substances, namely cations and anions, is urgent and widely sought due to the enormous impact that some of these chemical species have on human health and on the environment. Here, we present a new platform for the efficient sensing of Cu and Li cations. For this purpose, two novel photoactive diketopyrrolopyrrole-rhodamine conjugates were synthesized through the condensation of a diketopyrrolopyrrole dicarbaldehyde with rhodamine B hydrazide.

View Article and Find Full Text PDF

Details on the unexpected formation of two new (dimethylamino)methyl corrole isomers from the reaction of 5,10,15-tris(pentafluorophenyl)corrolatogallium(III) with sarcosine and paraformaldehyde are presented. Semi-empirical calculations on possible mechanism pathways seem to indicate that the new compounds are probably formed through a Mannich-type reaction. The extension of the protocol to the free-base 5,10,15-tris(pentafluorophenyl)corrole afforded an unexpected new seven-membered ring corrole derivative, confirming the peculiar behavior of corroles towards known reactions when compared to the well-behaved porphyrin counterparts.

View Article and Find Full Text PDF

Diketopyrrolopyrrole (DPP) derivatives containing sulfonamide (Sulfonamide-DPP), pyridyl (Dipyridyl-DPP) and N-methylpyridyl (MePyridyl-DPP) substituents were assessed as antibacterial photosensitizers. Non-charged DPPs showed an intense absorption band centered at about 480 nm and green fluorescence emission (Φ  ~ 0.7) in acetonitrile.

View Article and Find Full Text PDF

The photodynamic inactivation (PDI) of microorganisms has gained interest as an efficient option for conventional antibiotic treatments. Recently, Si(IV) phthalocyanines (SiPcs) have been highlighted as promising photosensitizers (PSs) to the PDI of microorganisms due to their remarkable absorption and emission features. To increase the potential of cationic SiPcs as PS drugs, one novel (1a) and two previously described (2a and 3a) axially substituted PSs with di-, tetra-, and hexa-ammonium units, respectively, were synthesized and characterized.

View Article and Find Full Text PDF

Telomerase, oncogenes and tumor suppressors are closely associated with tumour occurrence, therefore these structures are being recognized as targets for the development of new anticancer drugs. The efficacy of several molecules in telomerase inhibition and regulation of genes expression, by adduct formation with G-quadruplexes (G4), has been studied by biophysical and biochemical methods with promising results. We report here the synthesis and structural characterization of a small positively charged diketopyrrolo[3,4-c]pyrrole derivative, identified as DPP(PyMe), that showed very promising results as G4 stabilizing ligand.

View Article and Find Full Text PDF

Melanoma is the most dangerous form of skin cancer, with an abrupt growth of its incidence over the last years. It is extremely resistant to traditional treatments such as chemotherapy and radiotherapy, but therapies for this cancer are gaining attention. Photodynamic therapy (PDT) is considered an effective modality to treat several types of skin cancers and can offer the possibility to treat one of the most aggressive ones: melanoma.

View Article and Find Full Text PDF

Diketopyrrolo[3,4-]pyrroles (DPP) are high-performance organic optoelectronic materials. They have applications in solar cells, fluorescent probes, bioimaging, photodynamic/photothermal therapy, and in many other areas. This article reports a convenient two-step synthesis of various DPP dyes from Pigment Red 254, an inexpensive commercial pigment.

View Article and Find Full Text PDF

Indomethacin is a potent non-steroidal anti-inflammatory drug (NSAID) with a strong selective inhibitor activity towards cyclooxygenase-2 (COX-2), an enzyme that is highly overexpressed in various tumour cells, being involved in tumourigenesis. Concomitantly, porphyrins have gained much attention as promising photosensitizers (PSs) for the non-invasive photodynamic therapy (PDT) of cancer. Herein, we report the design, and determine the singlet oxygen generation capacity and in vitro cellular toxicity of porphyrin- and chlorin-indomethacin conjugates (P2-Ind and C2-Ind).

View Article and Find Full Text PDF

Absorption and relaxation dynamics of electronic states of free-base, Co(II), Cu(II) and Zn(II) porphyrins bearing a β-(2,2-difluoro-1,3,2-dioxaborinin-5-yl) group were investigated in dimethyl sulfoxide by using distinct time-resolved spectroscopic techniques. Furthermore, excited state absorption cross-section spectra were determined by combining white light continuum Z-Scan and transient absorption techniques. In the case of the free-base (2H) and Zn(II) porphyrins, we were able to quantify singlet-triplet conversion by analyzing the evolution of time-resolved fluorescence.

View Article and Find Full Text PDF

Anionic species are one of the most common pollutants in residual and freshwaters. The presence of anthropogenic anions in water drastically increases the toxicity to living beings. Here, we report the preparation of a new optical active material based on tri(tosylamino)phthalocyanines grafted to ferromagnetic silica nanoparticles for anion detection and removal.

View Article and Find Full Text PDF

New porphyrin-pyrrolidine/pyrroline conjugates were prepared by revisiting 1,3-dipolar cycloaddition reactions between a porphyrinic azomethine ylide and a series of dipolarophiles. Cationic conjugates obtained by alkylation of the pyrrolidine/pyrroline cycloadducts showed ability to generate singlet oxygen and to produce iodine in presence of KI when irradiated with visible light. Some of the cationic derivatives showed photobactericidal properties towards a Gram-negative bioluminescent .

View Article and Find Full Text PDF

Photodynamic therapy (PDT) is a promising alternative to overcome the resistance of melanoma to conventional therapies. Currently applied photosensitizers (PS) are often based on tetrapyrrolic macrocycles like porphyrins. Unfortunately, in some cases the use of this type of derivative is limited due to their poor solubility in the biological environment.

View Article and Find Full Text PDF

Zinc(II) phthalocyanines (Pcs) peripherally decorated with 2,4,6-tris(dimethylaminomethyl)phenoxy groups (Pcs and ) and the corresponding quaternized derivatives (Pcs and ) were synthesized and their photodynamic inactivation (PDI) efficiency against recombinant bioluminescent was examined. The photophysical data revealed that the presence of the ammonium units on the Pc structures promotes a redshift of the absorption bands when compared with the corresponding nonquaternized ones. The ammonium-substituted Pcs and showed excellent stability in dimethylformamide, moderate photostability, and increased efficiency to generate singlet oxygen (O).

View Article and Find Full Text PDF

In this study, we report for the first time the use of four aza-dipyrromethenes (ADPMs) as photosensitizers for cancer PDT. The synthesis and characterization of the ADPMs and their photodynamic action against B16F10 melanoma cells were assessed. ADPM 2 is the best singlet oxygen generator and the most phototoxic (at 2.

View Article and Find Full Text PDF

Photodynamic inactivation of bacterial and fungal pathogens is a promising alternative to the extensive use of conventional single-target antibiotics and antifungal agents. The combination of photosensitizers and adjuvants can improve the photodynamic inactivation efficiency. In this regard, it has been shown that the use of potassium iodide (KI) as adjuvant increases pathogen killing.

View Article and Find Full Text PDF

The reaction of -tetrakis(pentafluorophenyl)porpholactone with azomethine ylides and nitrones affords pyrrolidine-fused and isoxazolidine-fused dihydroporpholactones that display, respectively, isobacteriochlorin- and chlorin-type UV-Vis spectra. These reactions are site-selective, yielding, respectively, 17,18- or 12,13-dihydroporpholactones. The crystal and molecular features of pyrrolidine-fused and isoxazolidine-fused dihydroporpholactones were unveiled from single-crystal X-ray diffraction studies.

View Article and Find Full Text PDF

The reaction between organic azides and alkyne derivatives via the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) is an efficient strategy to combine phthalocyanines and analogues with different materials. As examples of such materials, it can be considered the following ones: graphene oxide, carbon nanotubes, silica nanoparticles, gold nanoparticles, and quantum dots. This approach is also being relevant to conjugate phthalocyanines with carbohydrates and to obtain new sophisticated molecules; in such way, new systems with significant potential applications become available.

View Article and Find Full Text PDF

A PHP Error was encountered

Severity: Notice

Message: fwrite(): Write of 34 bytes failed with errno=28 No space left on device

Filename: drivers/Session_files_driver.php

Line Number: 272

Backtrace:

A PHP Error was encountered

Severity: Warning

Message: session_write_close(): Failed to write session data using user defined save handler. (session.save_path: /var/lib/php/sessions)

Filename: Unknown

Line Number: 0

Backtrace: