7.1. Synthesis 306 7.2. Spectroscopic and Redox Properties 307 7.2.1. Optical Spectroscopy 307 7.2.2. Redox Properties 310 7.2.3. Other Characterization Methods 312 8. seco-Porphyrazines 312 8.1. Synthesis 312 8.2. Spectroscopic and Redox Properties 312 8.2.1. Optical Spectroscopy 312 8.2.2. Redox Properties 313 8.2.3. Other Characterization Methods 313 9. Conclusions 313 10. Abbreviations 314 11. Acknowledgments 314 12. References 314

Low Symmetry Phthalocyanines and Their Analogues

An updated overview on the development of new photosensitizers for anticancer photodynamic therapy

Synthetic pathways to water-soluble phthalocyanines and close analogs

The purpose of this review is to compile preclinical and clinical results on phthalocyanines (Pcs) as photosensitizers (PS) for Photodynamic Therapy (PDT) and contrast agents for fluorescence imaging. Indeed, Pcs are excellent candidates in these fields due to their strong absorbance in the NIR region and high chemical and photo-stability. In particular, this is mostly relevant for their in vivo activation in deeper tissular regions. However, most Pcs present two major limitations, i.e., a strong tendency to aggregate and a low water-solubility. In order to overcome these issues, both chemical tuning and pharmaceutical formulation combined with tumor targeting strategies were applied. These aspects will be developed in this review for the most extensively studied Pcs during the last 25 years, i.e., aluminium-, zinc- and silicon-based Pcs.

/pdf/like-a-bolt-from-the-blue-phthalocyanines-in-biomedical-mlvpupy9u0.pdf

Like a Bolt from the Blue: Phthalocyanines in Biomedical Optics

Chlorophylls make Earth green, are the central constituents in the engine of photosynthesis, and not surprisingly have garnered immense attention. A chlorin, the core chromophore of a chlorophyll, is a dihydroporphyrin macrocycle that contains one pyrroline ring and three pyrrole rings. The dominant method for the synthesis of chlorins has entailed the derivatization of porphyrins. The present review covers the ostensibly simple conversion of porphyrins, regardless of synthetic or biological origin, to chlorins. The period covered encompasses the entire history since the beginnings of chlorin synthetic chemistry in the early 20th century through 2015. Representative transformations include hydrogenation, cycloaddition, annulation, and diverse “breaking and mending” approaches. Altogether, the synthesis of >1000 chlorins or chlorin-like compounds (containing >50 distinct pyrroline motifs) is described. Such diversity animates the question “what structural features are essential for a chlorin to resemble ch...

Synthetic Chlorins, Possible Surrogates for Chlorophylls, Prepared by Derivatization of Porphyrins

Chlorins: Natural Sources, Synthetic Developments and Main Applications

Syntheses of two water-soluble phthalocyanines (Pc) containing 5-aminolevulinic acid (ALA) linked to the core structure are described. These compounds were prepared by using original functionalizations, and they present remarkable structural and photophysical features, indicating that they could be applied to photodynamic therapy (PDT).

/pdf/synthesis-of-phthalocyanines-ala-conjugates-water-soluble-ft32ctrg2k.pdf

Synthesis of Phthalocyanines−ALA Conjugates: Water-Soluble Compounds with Low Aggregation

Synthesis and photophysical studies of a chlorin sterically designed to prevent self-aggregation

This review describes applications of light in photonic therapies, especially photodynamic therapy (PDT) which involves the combination of light, photosensitizer and oxygen. Relevant examples of porphyrins, chlorins and phthalocyanines were chosen and are presented, among the commercially available and presently under study photosensitizers of interest at the moment. Our objective is not to be exhaustive, but discuss the general ideas on PDT and photosensitizers as they demonstrate interaction with light and the human body.

/pdf/basic-concepts-and-applications-of-porphyrins-chlorins-and-u2u65ct633.pdf

Francisco F. de Assis

Papers

Chlorins: Natural Sources, Synthetic Developments and Main Applications

Synthesis of Phthalocyanines−ALA Conjugates: Water-Soluble Compounds with Low Aggregation

Synthesis and photophysical studies of a chlorin sterically designed to prevent self-aggregation

Basic Concepts and Applications of Porphyrins, Chlorins and Phthalocyanines as Photosensitizers in Photonic Therapies

Chlorins: Natural Sources, Synthetic Developments and Main Applications