Synthesis, aggregation and photophysical studies of A2B2 phthalocyanines: Novel archetypes for anticancer and antimicrobial photodynamic therapy

Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química Orgánica. Fecha de lectura: 14-02-2020Esta tesis tiene embargado el acceso al texto completo hasta el 14-08-2021En esta tesis doctoral se han desarrollado nuevos fotosensibilizadores para su aplicación en terapia fotodinámica. Este tratamiento aplica luz del espectro visible, sobre una molécula fotosensible capaz de activar el oxígeno molecular presente en el entorno celular, produciendo especies activadas citotóxicas de oxígeno, como oxígeno singlete, capaces de inducir muerte celular. Concretamente se han preparado fotosensibilizadores de segunda generación de tipo porfirinoide basados en ftalocianinas de Zn(II) (Zn(II)Pcs). En concreto, en este trabajo hemos elegido como objetivo la preparación de Zn(II)Pcs formadas por dos tipos de isoindoles con diferente sustitución, denominadas comúnmente como A2B2, que pueden presentar dos variantes estructurales, es decir, ABAB y AABB. Estas geometrías altamente orientadas, permiten combinar sustituyentes hidrófobos e hidrófilos para dar lugar a anfífilos con la capacidad de interaccionar con medios lipófilos celulares así como facilitar el transporte en medios acuosos. La Parte 1 de esta tesis doctoral está orientada a la preparación de Zn(II)Pcs ABAB. La síntesis en todos los casos está dirigida por el uso de un ftalonitrilo que presenta grupos voluminosos que impiden la formación de la especie AABB. Estos grupos voluminosos, además, poseen unidades fluoradas que dotan a la estructura final de unas características electrónicas peculiares. Esta particular sustitución, no solo evita fenómenos de agregación, unos de los principales factores limitantes del uso de macrociclos porfirinoides en terapia fotodinámica, sino que además potencia la capacidad de las ftalocianinas para producir especies reactivas de oxígeno, como oxígeno singlete. Hemos sido capaces de combinar este patrón de sustitución con sustituyentes hidrófilos formando anfífilos. La introducción de sustituyentes con cadenas de tipo polietilenglicol destruye eficientemente cultivos celulares in vitro de cáncer de piel y de cuello de útero, y se ha demostrado cómo el patrón de sustitución ABAB es más efectivo que otros dentro de la misma familia (A3B y A4). Por otra parte, la incorporación de grupos funcionales cargados positivamente convierte estos compuestos en antimicrobianos frente S. aureus y E. coli. En la Parte 2 de esta tesis doctoral se ha trabajado con Zn(II)Pcs de tipo AABB, las cuales se han preparado utilizando un conector binaftol que evita la formación de especies ABAB. En este caso el conectol binaftol presenta quiralidad por restricción conformacional, lo que ha permitido obtener Zn(II)Pcs quirales que pueden ser estudiadas y caracterizadas por dicroísmo circular. Este tipo de compuestos pueden presentar cierta capacidad de auto-ensamblaje dependiendo del medio elegido, y que está influida por el conector quiral. De nuevo la incorporación de sustituyentes hidrófilos permite la formación de especies anfifílicas, de tal forma que la organización inducida en medio acuoso ha dado lugar a la formación de nanoestructuras de tipo micelar o vesicular, mientras que en medios más apolares como puede ser el interior celular, se encuentran molecularmente disueltas. Concretamente se han preparado derivados AABB funcionalizados con cargas positivas, efectivos en la inactivación de bacterias Gram positivas y Gram negativas. Además, también se ha decorado el conector binaltol con cadenas de polietilenglicol y se ha hecho un estudio en profundidad de su capacidad de organización en medios polares como el agua

Assessing amphiphilic ABAB Zn(II) phthalocyanines with enhanced photosensitization abilities in in vitro photodynamic therapy studies against cancer

We have previously demonstrated that singlet oxygen photosensitization abilities of Zn(II) phthalocyanines (Zn(II)Pcs) are enhanced through α-functionalization with bulky fluorinated substituents (i.e., bis(trifluoromethyl)phenyl units) at facing positions of ABAB Zn(II)Pcs, where A and B refer to differently functionalized isoindoles. In this work, we have prepared the Zn(II)Pc ABAB 1 endowed with hydrophilic triethylene glycol monomethyl ether (i.e., at the A isoindoles) to provide solubility in aqueous media, together with its A3B and A4 counterparts, and compared their ability to behave as photosensitizers for photodynamic therapy. All photophysical data, aggregation studies and preliminary in vitro biological assays in cell cultures of SCC-13 (squamous cell carcinoma) and HeLa (cervical cancer cells), have proved ABAB 1 as the best photosensitizer of the seriesThis research was funded by MINECO, Spain (CTQ2017-85393-P and CTQ2016-78454-C2-1-R) , Instituto de Salud Carlos III and Feder Funds (FIS PI18/00708) and ERANET/MINECO EuroNanoMe

Boosting the singlet oxygen photosensitization abilities of Zn(ii) phthalocyanines through functionalization with bulky fluorinated substituents

In-depth, systematic photophysical studies have been performed on a series of ABAB, A3B and A4 ZnPcs functionalized with a varying number of bis(trifluoromethyl)phenyl units (i.e. at the B isoindoles) and other electron-withdrawing/electron-donating moieties (i.e. at the A isoindoles), to determine the influence of the susbtitution pattern on the aggregation features, fluorescence quantum yields and singlet oxygen (1O2) generation abilities of these molecules. As a general trend, the larger the number of bis(trifluoromethyl)phenyl units (i.e.ABAB crosswise functionalized ZnPcs), the lower the fluorescence quantum yield and the higher the 1O2 photosensitization. On the other hand, the electronic character of the substituents at the A isoindoles do not seem to have a clear effect on the photophysical properties of these ABAB ZnPcs. Overall, 1O2 quantum yields determined by the direct observation of the 1O2 phosphorescence are very high, with values ranging from 1 to 0.74 in THF solutionsThis work was supported by MINECO (CTQ2017-85393-P and CTQ2016-78454-C2-1-R) and ERA-NET/MINECO EuroNanoMed2017-191/PCIN-2017-04

Crosswise Phthalocyanines with Collinear Functionalization: New Paradigmatic Derivatives for Efficient Singlet Oxygen Photosensitization

This is the peer reviewed version of the following article: Revuelta‐Maza, M. A., Hally, C., Nonell, S., de la Torre, G., & Torres, T. (2019). Crosswise Phthalocyanines with Collinear Functionalization: New Paradigmatic Derivatives for Efficient Singlet Oxygen Photosensitization. ChemPlusChem, 84(6), 673-679, which has been published in final form at https://doi.org/10.1002/cplu.201800631. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived VersionsSupporting information for this article is available on the WWW under https://doi.org/10.1002/cplu.201800631We describe here the preparation of a series of trans-ABAB Zn(II) phthalocyanines (ZnPcs, which combine several interesting features. First, these compounds present high solubility and hindered aggregation, due to the functionalization of two facing isoindole constituents (B) of the ZnPc with bis(trifluoromethylphenyl) units. Second, the other two isoindoles (A) bear extra-annulated phthalimide units containing different substituents in the nitrogen positions, this feature results in a collinear arrangement of a variety of functional groups. Some of these collinearly functionalized ZnPcs are interesting building blocks for constructing either homo- or heteroarrays containing ZnPc units. Furthermore, the amphiphilic nature of some members of the series renders them interesting candidates for photosensitization of singlet oxygen. Photophysical studies on a model compound of the series have shown that these molecules are efficient singlet oxygen photosensitizers in both polar and apolar media, with 1O2 quantum yields (φΔ) as high as 0.74This work has been supported by MINECO, Spain (CTQ2017‐85393‐P and CTQ2016‐78454‐C2‐1‐R). C. H. thanks the European Social Funds and the SUR del DEC de la Generalitat de Catalunya for his predoctoral fellowships (Grant No. 2017 FI_B 00617 and 2018 FI_B1 00174

Fluorine-substituted tetracationic ABAB-phthalocyanines for efficient photodynamic inactivation of Gram-positive and Gram-negative bacteria

Herein, we report the synthesis and characterization of new amphiphilic phthalocyanines (Pcs), the study of their singlet oxygen generation capabilities, and biological assays to determine their potential as photosensitizers for photodynamic inactivation of bacteria. In particular, Pcs with an ABAB geometry (where A and B refer to differently substituted isoindole constituents) have been synthesized. These molecules are endowed with bulky bis(trifluoromethylphenyl) groups in two facing isoindoles, which hinder aggregation and favour singlet oxygen generation, and pyridinium or alkylammonium moieties in the other two isoindoles. In particular, two water-soluble Pc derivatives (PS-1 and PS-2) have proved to be efficient in the photoinactivation of S. aureus and E. coli, selected as models of Gram-positive and Gram-negative bacteriaThis work has been supported by MINECO, Spain (CTQ2017-85393-P and CTQ2016-78454-C2-1-R