bluuebunny/crossref_metadata_2025_split huggingface dataset:
New Scaffolds for the Delivery of Protease Sensitive Photosensitizer Prodrugs
Authors: Bouilloux Jordan , Sekkat Nawal , Babic Andrej , Lange Norbert 
Published: February 2020

Photodynamic therapy (PDT) is a non-invasive technique for the treatment of several diseases such as microbial infections, rheumatoid arthritis, age-related macular degeneration, and cancer. However, this therapeutic approach suffers from several drawbacks associated with the administration of conventional photoactive compounds, such as skin photosensitization, unfavorable physicochemical properties, and finally low selectivity for the diseased tissue.
To improve the selectivity of conventional photosensitizers (PS) we have developed quenched PS prodrugs based on poly (L) lysine and cyclopeptidic carriers that target up-regulated proteolytic activities related to certain diseases, including cancer. These compounds are based on energy transfer between multiple copies of PSs tethered to oligomeric carriers via protease sensitive peptide linkers, thus, silencing any photodynamic activity. Proteolytic digestion of the peptide results into the release of a PS peptidyl fragment thereby restoring photodynamic activity. These conceptually new compounds act through several complementary targeting mechanisms. They 1) accumulate preferentially in pathologic tissue, 2) target pathology-related proteases, 3) are taken-up selectively by abnormal cells, and 4) being selectively irradiated in the diseased area. Using poly(L)lysine based carriers we have designed quenched PS prodrugs that effectively image and treat prostate cancer. Unfortunately, due to their undefined chemical structure these prodrugs are not suitable for clinical use.
Therefore, we have proceeded to design defined quenched PS prodrugs based on a cyclopeptidic carrier vehicle. These novel prodrugs have a constrained secondary structure with a defined molecular weight and predefined number and positions of the PS peptide conjugates. Preliminary evaluation demonstrated that these compounds show the expected tendencies, i.e. increased quenching with increasing number PSs per carrier and digestion by recombinant target proteases including, uPA, Cathepsin B and MMPs. The influence of different design parameters has been investigated in vitro and in vivo. For instance, we have shown that high molecular weight PEGylation is unfavorable for high quenching efficiencies.
Furthermore, we have characterized quenched PS prodrugs with respect to activation and phototoxicity in human cancer cell lines with special emphasis on prostate and ovarian cancer. Furthermore, preliminary optimization of pharmacokinetics and biodistribution will be carried out in the chorioallantoic membrane model inoculated with tumor spheroids.
Finally, might be possible to translate the gained knowledge into other scientific fields such as for instance the improved drug delivery of chemotherapeutics using cyclopeptidic protease sensitive carriers or the targeted imaging of GLP-1 receptors through the multimerization of targeting moieties onto the cyclopeptidic scaffold.
Origin of Reactivity Differences Between Heme and Nonheme Iron(III)-Hydroperoxo Complexes
Authors: de Visser Sam 
Published: February 2020

The cytochromes P450 are important enzymes in human physiology involved in biodegradation and biosynthesis pathways in the body.1,2 They generally react with substrates in a catalytic cycle that includes two reduction and two proton transfer steps to form a high-valent iron(IV)-oxo heme cation radical species called Compound I.3 High-valent metal-oxo species are common intermediates in enzymatic processes and have been identified in heme as well as nonheme iron enzymes. Compound I is a versatile and efficient oxidant that is known to react with substrates via aliphatic hydroxylation, epoxidation, aromatic hydroxylation, alkane dehydrogenation, N-dealkylation, sulfoxidation etc. Many of these processes involve the reduction of Compound I; unfortunately, Compound I is short-lived, which makes experimental studies in the field complicated. To overcome this, we have done computational studies on enzymatic heme enzymes as well as synthetic model porphyrins and phthalocyanines with the aim to gain insight into the intricate details of the oxidant to gain insight into the electrochemistry of the active species and the catalyzed reaction mechanism. In the past, these studies assisted experimental efforts in the field and made predictions of reaction mechanisms. It was, for instance, shown that the precursor of Compound I in the catalytic cycle, namely Compound 0, is catalytically inactive for epoxidation, sulfoxidation and aromatic hydroxylation reactions. However, in a recent twist of events, our group showed that nonheme iron(III)-hydroperoxo can be catalytically active.4 To understand the difference in activity between heme and nonheme iron(III)-hydroperoxo, we studied the mechanisms of aromatic hydroxylation and haloperoxidation. These combined experimental and computational studies gave insight into the effects of axial and equatorial ligands on the chemical and catalytic properties of Compound 0 and Compound I. In addition, our studies established the effects of environmental perturbations on the properties and reactivities of Compound I, including hydrogen bonding interactions and secondary sphere amino acid interactions.
References:

P. R. Ortiz de Montellano (Ed.), Cytochrome P450: Structure, Mechanism and Biochemistry. 3rd ed.; Kluwer Academic/Plenum Publishers, New York, 2005.

K. M. Kadish, K. M. Smith, R. Guilard (Eds.), Handbook of Porphyrin Science. World Scientific Publishing Co., New Jersey, 2010.

S. P. de Visser, D. Kumar (Eds.), Iron-containing enzymes: Versatile catalysts of hydroxylation reaction in nature. RSC Publishing, Cambridge (UK), 2011.

A. S. Faponle, M. G. Quesne, C. V. Sastri, F. Banse, S. P. de Visser, Chem. Eur. J. 2014, in press.
Porphyrin-Functionalized Porous Silicon Nanoparticles for Photodynamic Therapy
Authors: Secret Emilie , Maynadier Marie , Gallud Audrey , Chaix Arnaud , Bouffard Elise , Gary-Bobo Magali , Marcotte Nathalie , Mongin Olivier , El Cheikh Khaled , Hugues Vincent , Auffan Melanie , Frochot Céline , Morère Alain , Maillard Philippe , Blanchard-Desce Mireille , Sailor M. J. , Garcia Marcel , Durand Jean-Olivier , Cunin Frederique 
Published: February 2020

Nanomaterials offer the potential for minimally invasive and focal therapies to reduce side-effects associated with systemic administration of anticancer drugs. Clinical treatment involving photodynamic therapy is particularly attractive since it allows spatial and temporal control of the production of highly cytotoxic singlet oxygen and reactive oxygen species through local excitation of a photosensitizer.
Porous silicon nanoparticles (pSiNP), obtained by electrochemical etching of crystalline silicon followed by ultrasonic treatment, are particularly attractive for nanomedicine because they are bioresorbable in vivo and their degradation product, silicic acid, is non-toxic. In addition pSiNP display intrinsic optical properties (luminescence) deriving from their semi-conductive nature, very usefull for imaging.
Here we will present simple photosensitizer/pSiNP systems based on a porphyrin derivative covalently attached to the nanoparticle, and demonstrate imaging and PDT in vitro under one (OPE) and two photon excitation (TPE) conditions. We will describe the preparation of the biodegradable pSiNP, the chemical functionalization of pSiNP with the photosensitizer by the covalent anchoring of a porphyrin into the porous silicon matrix using a new type of conjugation chemistry, as well as their functionalization with cancer cell targeting species. The targeting and photodynamic efficiency of the described formulations on various cancer cell lines will be presented. We will show that both types of excitation, OPE and TPE, lead to cell death through different excitation pathways.
Emilie Secret, Marie Maynadier, Audrey Gallud, Arnaud Chaix, Elise Bouffard, Magali Gary-Bobo, Nathalie Marcotte, Olivier Mongin, Khaled El Cheikh, Vincent Hugues, Mélanie Auffan, Céline Frochot, Alain Morère, Philippe Maillard, Mireille Blanchard-Desce, Michael J. Sailor, Marcel Garcia, Jean-Olivier Durand and Frédérique Cunin,Two-Photon Excitation of Porphyrin Functionalized Porous Silicon Nanoparticles for Photodynamic Therapy Adv. Mater.,
2014, Online. DOI: 10.1002/adma.201403415.
Emilie Secret,

Marie Maynadier,

Audrey Gallud, Magali Gary-Bobo, Arnaud Chaix, Emmanuel Belamie, Philippe Maillard,

Michael J. Sailor,

Marcel Garcia,

Jean-Olivier Durand,

Frédérique Cunin, Anionic porphyrin-grafted porous silicon nanoparticles for photodynamic therapy,Chem. Commun., 2013, 49(39), 4202-4204. DOI: 10.1039/C3CC38837A
Optoelectronic Properties of Metal-Free Binary Porphyrin Nanostructures
Authors: Mazur Ursula , Borders Bryan , Hipps K W 
Published: February 2020

Nanostructures fabricated from tetrapyridylphenyl porphyrin (TPyP) and tetrasulfonatophenyl porphyrin (TSPP) in a 1:1 ratio are conducting and also photoconducting. I-V curves for the nanorods (in a vacuum environment) were collected in the dark and with (405, 473, and 633 nm) illumination. These wavelengths fall within the absorption spectrum of the porphyrin solid and allow determination of an action spectrum. With illumination, the nanorods show a sharp increase in conductivity followed by a slow increase in conductivity over time until a saturation photocurrent is reached. Once the light is off, the current decays slowly over time. This is referred to as persistent photoconductivity. The TPyP:TSPP nanorods exhibit an increase in photo-conductivity with an applied positive gate voltage and a decrease with an applied negative gate voltage, consistent with the electrons acting as the primary mobile charge carrier. Quantification of the persistent photoconductive behavior and a model for electron transport through the nanostructures will be presented.
Heat-Treating Self-Assembled Metalloporphyrin As Electrocatalysts for Oxygen Reduction Reaction
Authors: Song Yujiang 
Published: February 2020

Proton exchange membrane fuel cell (PEMFC) is a clean and efficient energy-conversion technology, which has been widely expected to replace internal combustion engine to drive future vehicles. A crucial component of PEMFC is Pt/C electrocatalysts that are composed of 2-5 nm semi-spherical Pt particles supported on carbon. However, conventional Pt/C electrocatalysts confront the high costs, limited supply, low activity, easy poisoning and poor durability, preventing PEMFC from commercialization. To resolve these issues, new generation of electrocatalysts have to be rationally designed and synthesized. This talk will focus on the creation of non-precious metal electrocatalysts by heat-treating self-assembled metalloporphyrin molecules and the electrochemical performance toward oxygen reduction reaction. This work was partially supported by the National Key Basic Research Program of China (973 Project 2012CB215500), and National Natural Science Foundation of China (NSFC 21003114, 21103163 and 21373211).

References

[1] Y. J. Song, R. M. Garcia, R. M. Dorin, H. R. Wang, Y. Qiu, J. A. Shelnutt, Angew. Chem. Int. Ed.
2006, 45, 8126.
[2] Y. J. Song, R. E. Haddad, S. L. Jia, S. Hok, M. M. Olmstead, D. J. Nurco, N. E. Schore, J. Zhang, J. G. Ma, K. M. Smith, S. Gazeau, J. Pecaut, J. C. Marchon, C. J. Medforth, J. A. Shelnutt, J. Am. Chem. Soc.
2005, 127, 1179.
[3] Y. J. Song, R. M. Garcia, R. M. Dorin, H. R. Wang, Y. Qiu, E. N. Coker, J. E. Miller, J. A. Shelnutt, Nano Lett.
2007, 7, 3650.
[4] Y. J. Song, R. M. Dorin, R. M. Garcia, Y. B. Jiang, H. R. Wang, P. Li, Y. Qiu, F. van Swol, J. E Miller, J. A. Shelnutt, J. Am. Chem. Soc.
2008, 130, 12602.
[5] Y. J. Song, M. A. Hickner, S. R. Challa, R. M. Dorin, R. M. Garcia, H. R. Wang, Y. B. Jiang, P. Li, Y. Qiu, F. van Swol, C. J. Medforth, J. E. Miller, T. Nwoga, K. Kawahara, W. Li, , J. A. Shelnutt, Nano Lett.
200
9, 9, 1534.
[6] R. M. Garcia, Y. J. Song*, R. M. Dorin, H. R. Wang, A. M. Moreno, Y. B. Jiang, Y. M. Tian, Y. Qiu, C. J. Medforth, E. N. Coker, F. van Swol, J. E. Miller, J. A. Shelnutt*, Phys. Chem. Chem. Phys,
2011, 13,4846.
[7] W. F. Si, J. Li, H. Q. Li, J. Yin, H. Xu, X. W. Guo, T. Zhang, Y. J. Song*, Nano Research
2013, 6, 720.
[8] Y. Xie, H. Q. Li, C. Z. Tang, S. S. Li, J. Li, Y. Lv, X. M. Wei, Y. J. Song*, J. Mater. Chem. A
2014, 2, 1631.
[9] Y. Xie, C. Z. Tang, Z. Q. Hao, Y. Lv, R. X. Yang, X. M. Wei, W. Q. Deng, A. J. Wang, B. L. Yi, Y. J. Song*, Faraday Discuss.
2014, DOI: 10.1039/C4FD00121D.
[10] S. S. Li, H. Q. Li, Y. S. Zhang, R. M. Garcia, J. Li, Y. Xie, J. Yin, M. R. Li, J. H. Wang, J. A. Shelnutt, T. Zhang, Y. J. Song*, J. Mater. Chem. A
2014, DOI:10.1039/c3ta10406k.
Toward True Carbaporphyrinoids - Contraction of Benziporphyrins
Authors: Szyszko Bartosz , Kupietz Kamil , Hurej Karolina , Kedzia Aneta , Latos-Grazynski Lechoslaw 
Published: February 2020

A replacement of a single pyrrole of meso-tetraarylporphyrin by cyclopentadiene moiety seems to be a notion of the very first choice for the creation of meso-substituted or β-substituted 21-carbaporphyrins which ideally conserve the fundamental frame of porphyrin, seen also in 21-heteroporphyrins and in the first metallaporphyrin (21-pallada-23-tellura-porphyrin).[3] The construction of a true carbaporphyrin requires a replacement of the imine nitrogen of pyrrolene by a trigonally hybridized methine unit or amine NH of pyrrole by a tetrahedral methylene group affording a tautomeric couple (2 and 3) which is parental for all monocarbaporphyrinoids. It remains a challenge to create 5,10,15,20-tetraaryl-21-carbaporphyrins that are potentially amenable to diverse structural modifications.The remarkable, facile contraction of p-phenylene embedded in p-benziporphyrin 1 to cyclopentadiene, mediated by transition metal cation of 2-M produced complexes of 21-carbaporphyrins 2-M or 3-M.[1,2] Thus these investigations afforded 5,10,15,20-tetraaryl- 21-carbaporphyrin - the first example of true carbaporphyrin complexes, which are firmly stabilized via coordination of trigonal (2-M) or tetrahedral (3-M) carbon donors. One can expect the true carbaporphyrins can prompt developments in carbaporphyrinoid and organometallic chemistry building on specific reactivity of cyclopentadienyl moiety.

References

[1] Szyszko, B.; Latos-Grazynski, L.; Szterenberg, L. Angew. Chem. Int. Ed.
2011, 50, 6587.
[2] Szyszko, B.; Kupietz, K.; Szterenberg, L.; Latos-Grazynski, L. Chem. Eur. J.
2014, 20, 376.
[3] Pacholska-Dudziak E.; Szczepaniak, M.; Ksiazek, A.; Latos-Grazynski, L. Angew. Chem. Int. Ed.
2013, 52, 8898.

Figure 1
Electro- and Photo-Catalytic Reduction of Small Molecules/Ions By Corrole Metal Complexes
Authors: Gross Zeev , Mahammed Atif 
Published: February 2020

The scientific interest in the macrocyclic metal chelating corroles has evidenced a remarkable increase since our discovery of their first one-pot synthesis in 1999. Facile synthetic modifications that were introduced during the latest years now allow for tuning of the most fundamental properties of corroles, such as lipo-/hydro-/amphilicity, photo-excited states and their mode of decay to the ground state, and the stability/reactivity profiles of the corresponding metal complexes.
The impact of these investigations is exemplified by the introduction of corrole metal chelates as catalysts for the most important chemical reactions involved in energy-relevant processes, such as the hydrogen and oxygen evolution reactions. This presentation will focus on the largely unexplored potential of metallocorroles for the reduction of protons to hydrogen and of halides to halogens, via electrocatalysis and photocatalysis, respectively. Tuning of reactivity and redox potentials is achieved by variations introduced onto the ligand and the choice of coordinated metal ions.
REFERENCES
“Four-Electron Oxygen Reduction by Brominated Cobalt Corrole” Inorg. Chem.
2012, 51, 22-24.
“Cobalt Corrole Catalyst for Efficient Hydrogen Evolution Reaction from H2O under Ambient Conditions: Reactivity, Spectroscopy and DFT Calculations”, Inorg. Chem.
2013, 52, 3381-3387.
"The Cobalt Corrole Catalyzed Hydrogen Evolution Reaction: Surprising Electronic Effects and Characterization of Key Reaction Intermediates" Chem. Commun.
2014, 50, 2725-2727.

Figure 1
Pyrrole-Fused Azacoronenes with Various Redox States
Authors: Takase Masayoshi 
Published: February 2020

Polycyclic aromatic hydrocarbons represented by hexabenzocoronenes (HBC) have attracted a great deal of attention from materials science. Among them, nitrogen-containing π-system have potential advantages since such heteroatoms can tune the electronic nature without modifying the structure. Given these expectations, we have reported a novel nitrogen-containing π-system, i.e., hexapyrrolohexaazacoronene (HPHAC). To investigate the effect of the interior nitrogen atoms, we have recently synthesized a series of pyrrole-fused azacoronenes, where some pyrrole rings of HPHAC were substituted with phenyl rings. In all cases, they showed multiple oxidation states due to the interior nitrogen atoms and various resonance forms.
The synthesis was successively performed by SNAr reaction with fluoroiodobenzenes, Suzuki-Miyaura coupling, and oxidative Scholl reaction. As characteristic features, cyclic voltammograms exhibit up to three reversible oxidation peaks having similar first two oxidation potentials and differences between second and third oxidation potentials become smaller in order of decreasing the number of pyrroles. Chemical oxidations by monitoring the absorption spectra revealed that these compounds had different electronic states in their oxidation states. Recently, we have further designed and synthesized a new family that has two carbonyl groups directly introduced to the π-system. It is expected that the resonance forms observed for the oxidation states of previous azacoronenes become possible in the neutral state. As the result, new ones exhibit significantly different physical properties.
In the presentation, synthesis and optical and electronic properties of azacoronenes will be discussed.
Structures and Reactivity of Group 9 Metalloporphyrin Complexes
Authors: Anding Bernie J. , Dairo Taiwo O. , Woo L. Keith 
Published: February 2020

The importance of metalloporphyrins is highlighted by their wide occurrence and use in nature. Essential biological roles of metalloporphyrins include electron-, energy-, and oxygen-transfer, oxygen activation, and diverse functions in enzyme active sites. Due to a broad range of physical and chemical properties, metalloporphyrins have been modified for a variety of applications such as novel components in advanced materials, sensors, medical research, and synthetic chemistry. Metalloporphyrins are also of great utility for non-biological chemical catalysis, spanning reactions such as aziridination,1 C-H activation,1 and olefination.2 Moreover, metalloporphyrins are useful, atom-efficient catalysts for the generation of new carbon-carbon and heteroatom bonds using diazo carbonyl compounds.1 Thus, understanding the structures and reactivities of metalloporphyins is vital for developing and optimizing new uses.
Our current work focuses on group 9 (Rh, Ir) metalloporphyrins. This includes probing the reactivity of coordination complexes and determining the structures of the subsequent products.3 Recently, tetratolylporphyrinato (TTP) methyliridium, Ir(TTP)CH3, was shown to be an active and robust catalyst for the cyclopropanation of olefins using diazo reagents as carbene sources.4 Ir(TTP)CH3 also catalyzes N–H insertion reactions between ethyl diazoacetate (EDA) or methyl phenyldiazoacetate (MPDA) and a variety of aryl, aliphatic, primary, and secondary amines.5 Reactions with aryl amines produce the highest yields with up to 105 catalyst turnovers and without the need for slow addition of the diazo reagent. Mechanistic aspects of diazo insertion reactions are examined. In addition, a comparison of the molecular structures of RhIII(TTP) and IrIII(TTP) carbene complexes provides insights for understanding reactivity differences for the two metals complexes.6

References

1. Anding, B. J.; Woo, L. K. In Handbook of Porphyrin Science; Kadish, K. M., Guilard, R., Smith, K., Eds.; World Scientific Publishing Company: Hackensack, NJ, 2012; Vol. 21, p 145.
2. Mirafzal, G. A.; Cheng, G.; Woo, L. K. J. Am. Chem. Soc.
2002, 124, 176-177.
3. Dairo, T. O.; Ellern, A.; Angelici, R. J.; Woo, L. K. Organometllics, 2014, 33, 2266-2276.
4. Anding, B. J.; Ellern, A.; Woo, L. K. Organometallics
2012, 31, 3628-3635.
5. Anding, B. J.; Woo, L. K. Organometallics, 2013, 32, 2599-2607.
6. Anding, B. J.; Ellern, A.; Woo, L. K. Organometallics, 2014, 33, 2219-2229.

Figure 1
Asymmetric Oxidation and Carbene Transfer Reactions Catalyzed By Metalloporphyrins in Water
Authors: Simonneaux Gerard , Le Maux Paul , Carrie Daniel , Chevance Soizic 
Published: February 2020

The development of environmentally benign reactions is an important goal in synthetic organic chemistry and chemical engineering. However, catalytic enantioselective reactions using transition-metal complexes in protic or aqueous solvents are within limited ranges. The current applications of asymmetric catalysis using metalloporphyrins will be reported (1). Distinct methodologies have been developed for carbene transfer and oxidation reactions such as the use of water-soluble catalysts (2). Comparison between hydrophobic and hydrophilic solvents will be discussed from an asymmetric point of view.
Catalytic enantioselective oxidations using transition-metal complexes are limited when the oxidant is hydrogen peroxide. The two main difficulties of using hydrogen peroxide in the presence of transition metal complexes are the homolytic cleavage generating OH radicals and the catalase reaction with formation of dioxygen. Asymmetric sulfoxidation, epoxidation of alkenes and hydroxylation catalyzed by iron and manganese porphyrins will be described (3). Thus the asymmetric epoxidation of styrene derivatives by H2O2 (or UHP) to give optically active epoxides (ee up to 81%) and hydroxylation of alkanes to give optically active secondary alcohols (ee up to 78%) were carried out in methanol and water using chiral water-soluble iron porphyrins as catalysts.
(1) Recent Advances in Catalysis by Water-Soluble Metalloporphyrins
G. Simonneaux, P. Le Maux, S. Chevance and H. Srour. Handbook of Porphyrin Science, 2012, Vol. 21, 377-410
(2) Enantioselective Manganese-Porphyrin-Catalyzed Epoxidation and C-H hydroxylation with Hydrogen Peroxide in Water/Methanol Solutions
H. Srour, P. Le Maux and G. Simonneaux. Inorg. Chem. 2012, 51, 5850-5856.
(3) Metal-catalyzed asymmetric sulfoxidation, epoxidation and hydroxylation by hydrogen peroxide
Hassan Srour, Paul Le Maux, Soizic Chevance, Gérard Simonneaux. Coord. Chem. Rev., 257 (2013) 3030– 3050