Photosensitized Oxidation of Intracellular Targets: Understanding the Mechanisms to Improve the Efficiency of Photodynamic Therapy.

The development of improved photosensitizers is a key aspect in the establishment of photodynamic therapy (PDT) as a reliable treatment modality. In this chapter, we discuss how molecular design can lead to photosensitizers with higher selectivity and better efficiency, with focus on the importance of specific intracellular targeting in determining the cell death mechanism and, consequently, the PDT outcome.

A giant hybrid organic-inorganic octahedron from a narrow rim carboxylate calixarene.

Here we discovered an unprecedented giant octahedral coordination compound bearing 16 Zn2+, 12 Na+, 8 O2-, 4 OH-, 13 H2O and 6 L4- ligands [L4- = fully deprotonated tetra(carboxymethoxy)calix[4]arene]. Its structure was elucidated by single-crystal X-ray diffraction, wavelength-dispersive X-ray spectroscopy and MALDI-TOF mass spectrometry. This compound, Zn8Na6L6⊃Zn8Na6O8(OH)4(H2O)13 (external⊃internal), has eight tetrahedral zinc ions forming the coordination vertices of an outermost cube where carboxylate groups from the sodium calixarenes are anchored.

Reducing zirconium(IV) phthalocyanines and the structure of a Pc(4-)Zr complex.

The synthesis and characterization of the ring-unsubstituted zirconium phthalocyanine PcZrCl2 (; Pc(x-) = phthalocyaninato(x-)) and its reduction products are described. X-ray analysis of (crystallized from hot 1-chloronaphthalene) reveals that is a chloride-bridged dimer [PcZrCl]2(μ-Cl)2 in the solid-state; was also characterized by UV-vis/MCD spectroscopy and cyclic voltammetry, which indicated reduction potentials at -0.55, -0.

Metallophthalocyanin-ocenes: scandium phthalocyanines with an η(5)-bound Cp ring.

A series of new scandium complexes supported by the phthalocyanine (Pc) ligand have been prepared and structurally characterized. Reaction of ScCl3 with phthalonitrile affords a mixture of PcScCl (1) and unreacted ScCl3, which upon addition of LiCH(SiMe3)2 yields THF-soluble PcSc(μ-Cl2)Li(THF)2 (2). Metathesis with NaCp or LiCp* generates PcSc(η(5)-C5H5) and PcSc(η(5)-C5Me5), respectively, which represent the first examples of η(5)-Cp metal phthalocyanines where the Cp fragment sandwiches the metal centre.

Dinitriles bearing AIE-active moieties: synthesis, E/Z isomerization, and fluorescence properties.

Dinitriles bearing aggregation-induced emission (AIE)-active moieties [tetraphenylethylene (TPE) or diphenylphenanthrene (DPP)] were prepared. Compounds 4 (TPE-linked) and 8 (DPP-linked) showed considerably redshifted emission resulting from their large Stokes shifts and also strong fluorescence in the aggregated and solid states. Pure E and Z stereoisomers of both dinitriles were easily separated, and their isomerization equilibria and fluorescence properties were investigated.

Synthesis of new chlorin e6 trimethyl and protoporphyrin IX dimethyl ester derivatives and their photophysical and electrochemical characterizations.

In view of increasing demands for efficient photosensitizers for photodynamic therapy (PDT), we herein report the synthesis and photophysical characterizations of new chlorin e6 trimethyl ester and protoporphyrin IX dimethyl ester dyads as free bases and Zn(II) complexes. The synthesis of these molecules linked at the β-pyrrolic positions to pyrano[3,2-c]coumarin, pyrano[3,2-c]quinolinone, and pyrano[3,2-c]naphthoquinone moieties was performed by using the domino Knoevenagel hetero Diels-Alder reaction. The α-methylenechromanes, α-methylenequinoline, and ortho-quinone methides were generated in situ from a Knoevenagel reaction of 4-hydroxycoumarin, 4-hydroxy-6-methylcoumarin, 4-hydroxy-N-methylquinolinone, and 2-hydroxy-1,4-naphthoquinone, respectively, with paraformaldehyde in dioxane.

An exemplary relationship between the extent of cofacial aggregation and fluorescence quantum yield as exhibited by quaternized amphiphilic phthalocyanines.

The aggregation equilibrium of a series of positively-charged water-soluble phthalocyanines (Pcs) was studied in aqueous solution by means of absorption and fluorescence techniques. The aggregation equilibrium in water depends on the bridging atoms between the pyridyl groups and the Pc core, and on the central metal of the Pcs, while N-alkyl groups are virtually uninvolved in the aggregation properties. Thus, in the water-methanol mixture, the aggregation tendency increased in the order of Zn < Cu ≤ Ni, Pd when the ligand is the same, while the bridging element sulfur gives much more propensity for aggregation compared to oxygen.

Absorption and electrochemical properties of cobalt and iron phthalocyanines and their quaternized derivatives: aggregation equilibrium and oxygen reduction electrocatalysis.

The synthesis and investigation of the electronic properties of Co(II) and Fe(II)tetrakis(pyridine-3-yloxy)phthalocyanines, as well as the respective quaternized complexes, are reported here. After quaternization reaction, the compounds showed increased solubility in water, and their aggregation equilibrium was analyzed by varying the solution concentration, pH, and composition. Cyclic voltammograms of the four compounds showed both metal and ring centered redox processes, with the former being highly sensitive to methylation of the pyridyl groups.