On the energy gap determination of organic optoelectronic materials: the case of porphyrin derivatives

A correct determination of the ionization potential (IP) and electron affinity (EA) as wells as the energy gap is essential to properly characterize a series of key phenomena related to...

Porphyrin/Chlorin Derivatives as Promising Molecules for Therapy of Colorectal Cancer

Colorectal cancer (CRC) is a leading cause of cancer-related death. The demand for new therapeutic approaches has increased attention paid toward therapies with high targeting efficiency, improved selectivity and few side effects. Porphyrins are powerful molecules with exceptional properties and multifunctional uses, and their special affinity to cancer cells makes them the ligands par excellence for anticancer drugs. Porphyrin derivatives are used as the most important photosensitizers (PSs) for photodynamic therapy (PDT), which is a promising approach for anticancer treatment. Nevertheless, the lack of solubility and selectivity of the large majority of these macrocycles led to the development of different photosensitizer complexes. In addition, targeting agents or nanoparticles were used to increase the efficiency of these macrocycles for PDT applications. On the other hand, gold tetrapyrrolic macrocycles alone showed very interesting chemotherapeutic activity without PDT. In this review, we discuss the most important porphyrin derivatives, alone or associated with other drugs, which have been found effective against CRC, as we describe their modifications and developments through substitutions and delivery systems.

Synthesis and ESR studies of multiphenyl porphyrins

The synthesis of tetra biphenyl and tetra triphenyl derivatives of porphyrin has been achieved with relative ease, and although the compounds show the expected low solubility in organic solvents, their tendency to form aggregates was observed. They are sufficiently dispersed to allow characterization by 1H, 13C, mass spectrometry, and determine their photophysical properties. The presence of 8 hydroxyl groups and 12 aromatic rings in the structure of the porphyrin showed to be able to stabilize the superoxide anion. This approach allows the possibility of using these compounds as building blocks and could be applicable to synthesizing other highly structurally uniform and well-defined porphyrin derivatives in good yields.

Molecular persistent luminescence imaging with porphyrin derivatives for ultrasensitive image-guided cancer surgery and drug screening

Persistent luminescence without excitation light and tissue autofluorescence interference holds great promise for in vivo imaging and sensing. However, the availability of persistence luminescence materials is largely limited by potential toxicity, instability, short-wavelength emissions, and poor clinical potential for currently available ones. Here we report a series of porphyrin derivatives with near-infrared (NIR) persistence luminescence for image-guided cancer surgery and drug screening. These porphyrin derivatives showed NIR persistence luminescence over 760 nm after cessation of excitation light or upon interaction with peroxynitrite (ONOO-), and a plausible mechanism of ordered oxidation of vinylene bond is proposed. Through molecular engineering with adaptive peptides bearing the functions of β-sheet-formatting and cancer cell targeting, the resultant Ppa-FFGYSA supermolecular probe showed enhanced photoacoustic and persistence luminescence signals, facilitating preoperative photoacoustic tumor identification and intraoperative persistence luminescence image-guided tumor resection with outperformed signal-to-background ratio. In addition, the activated persistence luminescence in recognition of ONOO- also permits the specific monitoring of neutrophil infiltration and screening of immunogenic cell death (ICD) drugs with high sensitivity and specificity.

Nanoarchitectonics with porphyrins and related molecules

An emerging concept, nanoarchitectonics, is supposed to work on the preparation of functional materials systems from nanoscale components. Because porphyrin derivatives show their importance in many research targets, discussions on nanoarchitectonics with porphyrins and related molecules would provide meaningful opportunities to consider effective usages of the nanoarchitectonics. This review article explains various examples of nanoarchitectonics approaches with porphyrin derivatives. The examples are especially focused on two topics: (i) materials nanoarchitectonics for nanofibers, metal-organic frameworks, covalent organic frameworks, and hydrogen-bonded organic frameworks; (ii) interfacial nanoarchitectonics for surface monolayers (self-assembled monolayers), Langmuir-Blodgett films, and layer-by-layer assemblies. Functions and properties can be enhanced upon their organization in specific dimensions and arrangements in nanostructured frameworks. In many cases, interface-specific organization would lead to advanced performances with high efficiency and specificity. Even though only limited examples are described here, various possibilities are actually suggested. Not limited to porphyrin families, nanoarchitectonics for functional materials has to be considered with a wide range of materials.

Photoinactivation Efficiency of Cationic Porphyrin Derivatives Against Multidrug-Resistant Wound Pathogens

The photoinactivation efficiency of antimicrobial photodynamic therapy (aPDT) with cationic porphyrin derivatives (CPDs) against multidrug-resistant (MDR) bacterial strain was assessed. MDR bacterial strains including Pseudomonas aeruginosa, Escherichia coli, Acinetobacter baumannii, and Klebsiella pneumoniae were used. The CPDs named PM, PE, PN, and PL were synthesized as a photosensitizer (PS). A diode laser with a wavelength of 655 nm was used as a light source. Photoinactivation efficiency of the combinations formed with different energy density (50, 100, and 150 J/cm²) and PS concentrations (ranging from 3.125 µM and 600 µM) on each bacterial strain were evaluated. Toxicity of the aPDT combinations that showed a strong photoinactivation on the bacterial strains and dark toxicity of PSs and were evaluated on fibroblasts cells. In the aPDT experiments, survival reductions of up to 5.80 log₁₀ on E. coli, 5.90 log₁₀ on P. aeruginosa, 6.11 log₁₀ on K. pneumoniae and 6.78 log₁₀ on A. baumannii were obtained. There was an increase in the photoinactivation efficiency in parallel with increasing the energy density, and the best effect seen at an energy density of 150 J/cm2. PL did not show any toxic effect on fibroblasts. However, other PSs were toxic in fibroblasts at high concentrations. In this research, which reflected the results of in vitro experiments, aPDT provided potent photoinactivation against MDR clinical isolates. The research results lead to an in vivo wound model study of aPDT with CPD infected with an MDR clinical isolate.