Search

Porphyrins bearing imidazolium salts were synthesized and used as N-heterocylic carbene (NHC) precursors for the preparation of gold(I) complexes. The dark toxicity and phototoxicity of the obtained compounds were investigated in vitro on MCF-7 breast cancer cells. The obtained data showed that porphyrins equipped with imidazolium salts are non-toxic in the dark and present interesting photodynamic properties. On the contrary, corresponding NHC-gold(I) complexes are not suitable photosensitizers for photodynamic therapy (PDT) applications. Their dark toxicity strongly depends on the nature of the linker between the porphyrin core and the NHC. This work was extended to the synthesis of a pyropheophorbide a derivative with a pendant imidazolium group for PDT applications using excitation wavelengths of 450 nm, 545 nm, and importantly of 650 nm.

Three new tetraphenylethene (TPE) push–pull chromophores exhibiting strong intramolecular charge transfer (ICT) are described. They were obtained via [2 + 2] cycloaddition–retroelectrocyclization (CA-RE) click reactions on an electron-rich alkyne-tetrafunctionalized TPE (TPE-alkyne) using both 1,1,2,2-tetracyanoethene (TCNE), 7,7,8,8-tetracyanoquinodimethane (TCNQ) and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) as electron-deficient alkenes. Only the starting TPE-alkyne displayed significant AIE behavior, whereas for TPE-TCNE, a faint effect was observed, and for TPE-TCNQ and TPE-F4-TCNQ, no fluorescence was observed in any conditions. The main ICT bands that dominate the UV–Visible absorption spectra underwent a pronounced red-shift beyond the near-infrared (NIR) region for TPE-F4-TCNQ. Based on TD-DFT calculations, it was shown that the ICT character shown by the compounds exclusively originated from the clicked moieties independently of the nature of the central molecular platform. Photothermal (PT) studies conducted on both TPE-TCNQ and TPE-F4-TCNQ in the solid state revealed excellent properties, especially for TPE-F4-TCNQ. These results indicated that CA-RE reaction of TCNQ or F4-TCNQ with donor-substituted are promising candidates for PT applications. [ABSTRACT FROM AUTHOR]

Electronic and steric properties of NHC ligands functionalized with porphyrins were investigated. When porphyrins are used as NHC-wingtips, nickel(II) in the macrocyle significantly improves the catalytic activity of the neighbouring NHC-Rh(I) complex in the conjugate addition of phenylboronic acid to cyclohexen-2-one. [ABSTRACT FROM AUTHOR]

Dynamic covalent polymers (DCPs) offer opportunities as adaptive materials of particular interest for targeting, sensing and delivery of biological molecules. In this view, combining cationic units and fluorescent units along DCP chains is attractive for achieving optical probes for the recognition and delivery of nucleic acids. Here, we report on the design of acylhydrazone-based DCPs combining cationic arginine units with π-conjugated fluorescent moieties based on thiophene-ethynyl-fluorene cores. Two types of fluorescent building blocks bearing neutral or cationic side groups on the fluorene moiety are considered in order to assess the role of the number of cationic units on complexation with DNA. The (chir)optical properties of the building blocks, the DCPs, and their complexes with several types of DNA are explored, providing details on the formation of supramolecular complexes and on their stability in aqueous solutions. The DNA-templated formation of DCPs is demonstrated, which provides new perspectives on the assembly of fluorescent DCP based on the nucleic acid structure. [ABSTRACT FROM AUTHOR]

Synthesis of fluorescent P‐hydroxybinaphtylphosphole‐oxide or ‐sulfide was achieved by trapping a binaphtyl dianion with methyl dichlorophosphite or P‐(N,N‐diethylamino)dichlorophosphine, followed by oxidation or sulfuration of the P‐center. After saponification or acid hydrolysis, the P‐hydroxyphospholes were coupled to peptides using the coupling agent BOP, under the conditions required for the synthesis in solution or on a solid support. This new method was illustrated by the labeling of the JMV2959, a potent antagonist of the Growth Hormone Secretagogue Receptor type 1a (GHS−R1a). The labeled conjugates were used to characterize GHSR ligands by competition assays, based on Fluorescence Resonance Energy Transfer (FRET). Such P‐hydroxyphosphole‐oxide or ‐sulfide constitute a promising new class of compact fluorophores with large Stokes shift, for labeling biomolecules by grafting through the phosphorus atom. [ABSTRACT FROM AUTHOR]

The synthesis, characterization and study of optical properties of innovative tetrafunctionalized zinc(II) porphyrins with carbonic anhydrase (CA) inhibitors in sulfonamide and coumarin series are described. The synthetic methodology relies on the preparation of the porphyrin core by condensation of azido triethyleneglycol functionalized benzaldehyde derivative with pyrrole followed by its metalation and inhibitors coupling via Huisgen click‐reaction. The tetrafunctionalized zinc(II) porphyrin with coumarin moieties showed selective inhibition against tumour‐associated hCA IX and hCA XII versus the cytosolic off‐targets hCA I and hCA II. This compound was able to accumulate on cell membrane and to impair pancreas cancer cells (Capan‐1) proliferation in normoxic conditions with LC50 of 4.5 μM. Moreover, its optical properties revealed efficient photosensitizing properties, leading to cancer cells death under light irradiation, making this compound a suitable candidate for photodynamic therapy. [ABSTRACT FROM AUTHOR]

Aggregation-induced emitters – or AIEgens – are often symbolised by their photoluminescence enhancement as a result of aggregation in a poor solvent. However, for some applications, it is preferable for the AIE response to be induced in the solid-state. Here, the ability of an organic–inorganic hybrid polymer host to induce the AIE response from embedded silole-based lumophores has been explored. We have focussed on understanding how the incorporation method controls the extent of lumophore aggregation and thus the associated photophysical properties. To achieve this, two sample concentration series have been prepared, based on either the parent AIEgen 1,1-dimethyl-2,3,4,5-tetraphenylsilole (DMTPS) or the silylated analogue (DMTPS-Sil), which were physically doped or covalently grafted, respectively, to dU(600) – a member of the ureasil family of poly(oxyalkylene)/siloxane hybrids. Steady-state and time-resolved photoluminescence measurements, coupled with confocal microscopy studies, revealed that covalent grafting leads to improved dispersibility of the AIEgen, reduced scattering losses, increased photoluminescence quantum yields (up to ca. 40%) and improved chemical stability. Moreover, the ureasil also functions as a photoactive host that undergoes excitation energy transfer to the embedded DMTPS-Sil with an efficiency of almost 70%. This study highlights the potential for designing complex photoluminescent hybrid polymers exhibiting an ehanced AIE response for solid-state optical applications. [ABSTRACT FROM AUTHOR]

The first synthesis of an original octamer consisting of a central polyhedral oligomeric silsesquioxane (POSS) cage decorated with electro- and optically active arylamine-based push–pull building-blocks is reported herein. Once fully characterized, the potential of the new compound was evaluated as donor material in bulk heterojunction organic solar cells. With promising power conversion efficiencies, good processability and film forming properties, such multimer architectures turns out to be potential candidates to bridge the gap between small molecules and polymers. [ABSTRACT FROM AUTHOR]

Phosphonium‐based polythiophene conjugated polyelectrolytes (CPEs) with three different counterions (dodecylsulfate, octylsulfate and perfluorooctane sulfonate) are synthesized to determine how the nature of the counterion affects the thermal properties, the self‐assembly in thin films and the performance as the cathode interfacial layer in polymer solar cells (PSCs). The counterion has a significant effect on the thermal properties of the CPEs, affecting both their glass transition and crystalline behaviour. Grazing‐incidence wide‐angle X‐ray scattering studies also indicate that changing the nature of the counterion influences the microstructural organization in thin films (face‐on versus edge‐on orientation). The affinity of the CPEs with the underlying photoactive layer in PSCs is highly correlated with the counterion species. Finally, in addition to an increase of the power conversion efficiency of ca 15% when using these CPEs as cathode interfacial layers in PSCs, a higher device stability is noted, compared to a reference device with a calcium interlayer. © 2020 Society of Industrial Chemistry [ABSTRACT FROM AUTHOR]

Porphyrins and N‐heterocyclic carbenes (NHCs) are both relevant ligands in the fields of coordination and organometallic chemistry. Despite evident structural differences, porphyrins and NHCs have a lot in common such as their ability to form strong metal‐ligand bonds and their use in catalysis, materials science and biomedicine. During the last decade, several molecular systems combining porphyrins and NHC ligands were reported in the literature. The present review gathers relevant examples where NHC ligands are either axially bonded to metalloporphyrins or covalently attached to the porphyrin cores. Structural diversity, electronic interplay between porphyrins and NHCs and some relevant applications in catalysis and biomedicine are notably described. Finally, molecular systems combining NHCs with other original porphyrinoids such as N‐confused porphyrins, subporphyrins and norcorroles are also presented. [ABSTRACT FROM AUTHOR]

Supramolecular polymers are of interest in the pursuit of multivalent nucleic acids recognition. However, their formation often relies on non‐covalent forces that are also at play in the interaction with nucleic acids. In this work, we designed a novel compound (TPE‐Gir) combining a tetraphenylethene aromatic core tethered to four quaternary ammoniums through acylhydrazone spacers, and we investigated in detail its self‐assembly and interaction with different types of nucleic acids. The spectroscopic analyses indicate the self‐assembly of regular fluorescent nanoparticles (observed by DLS and TEM) in the absence of nucleic acids, the strong propensity to intercalate into single‐stranded DNA, the ability to bind into the minor groove of double‐stranded DNA, and the selective binding to G‐quadruplex (G4) structures by fitting within a wide G4‐groove. Those recognition events are quantified by isothermal titration calorimetry and the proposed binding models are supported by docking simulations. [ABSTRACT FROM AUTHOR]

A series of 2,3-diphenylbuta-1,3-dienes (DPBs) bearing thiophene (T-DPB), bithiophene (BT-DPB) and ethylenedioxythiophene (EDOT-DPB) electropolymerizable units were prepared through desilylation reactions of the corresponding 3,4-diphenylsilole derivatives. These DPB derivatives exhibit remarkably different aggregation induced emission (AIE) or aggregation enhanced emission (AEE) behaviour depending on the strength of the molecular interactions occurring in the solid state. Indeed, T-DPB and EDOT-DPB were found to be good AIEgens while BT-DPB exhibited AEE behaviour. Finally, the electrochemical properties of these new materials were investigated revealing for all DPBs the occurrence of electropolymerization processes leading potentially to low band gap polymers. [ABSTRACT FROM AUTHOR]

Janus bis(N-heterocyclic carbenes) composed of a porphyrin core with two N-heterocyclic carbene (NHC) heads fused to opposite pyrroles were used as bridging ligands for the preparation of metal complexes. We first focused our attention on the synthesis of gold(I) chloride complexes [(NHC)AuCl] and investigated the substitution of the chloride ligand by acetylides to obtain the corresponding [(NHC)AuC≡CR] complexes. Polyacetylides were then used to obtain molecular multiporphyrinic systems with porphyrins fused to only one NHC ligand, while main-chain organometallic polymers (MCOPs) were obtained when using Janus porphyrin bis(NHCs). Interestingly, MCOPs incorporating zinc(II) porphyrins proved to be efficient as heterogeneous photocatalysts for the generation of singlet oxygen upon visible light irradiation. [ABSTRACT FROM AUTHOR]

Cationic polythiophenes constitute an interesting class of polymers for prospective applications in imaging, gene delivery and biosensing, as they combine solubility in aqueous media and have sensitive optical properties for the detection of biomolecules such as DNA. Here, we study the supramolecular self‐assembly of poly[3‐(6'‐(trimethylphosphonium)hexyl)thiophene‐2,5‐diyl] (P3HT‐PMe3) with different types of DNA such as single‐stranded oligonucleotides or long genomic DNA. Self‐assembly in buffered aqueous solution yields polyplexes (polymer/DNA complexes) with hydrodynamic radii ranging from 7 nm to around 25 nm, as observed by Taylor Dispersion Analysis. In these polyplexes, the achiral polymer presents chiroptical signals induced by supramolecular organization along chiral DNA. When the solution of long DNA/P3HT‐PMe3 is deposited on surfaces, tens of μm‐long fibers are formed by condensation of DNA and compaction of the polyplexes, as evidenced by microscopy techniques. [ABSTRACT FROM AUTHOR]

The synthesis of silole amino acids was achieved through hydrosilylation of alkene or alkyne‐containing amino acids with 1‐methyl‐2,3,4,5‐tetraphenyl‐1H‐silole, using Karstedt's catalyst with yield up to 95 % and without epimerization. After selective deprotection of carboxylic acid or amine functions respectively, C‐ or N‐peptide coupling with an alanine moiety proved their possible incorporation into peptides. A model tripeptide was synthesized by solid phase synthesis with the N‐Fmoc protected silole amino acid version. The silole moiety can be also grafted on a precursor peptide directly on the solid support. These amino acids and peptides exhibit AIE properties with λem ca. 500 nm and Δλ ca. 100 nm. This approach constitutes an alternative and promising strategy for incorporation of such AIE fluorogens to peptides. Silole amino acids were obtained by hydrosilylation of unsaturated amino acids with yield up to 95 %. After selective deprotection, C‐ or N‐peptide coupling was performed in solution or on solid support. They exhibit AIE properties (λem ca. 500 nm; Δλ ca. 100 nm) and constitute a promising strategy for incorporation of AIE fluorogens in peptides. [ABSTRACT FROM AUTHOR]

Diazachlorin and diazabacteriochlorin have been prepared through reduction of diazaporphyrin and their in vitro and in vivo activity in photodynamic therapy has been investigated. [ABSTRACT FROM AUTHOR]

Porphyrins are conjugated, stable chromophores with a central core that binds a variety of metal ions and an easily functionalized peripheral framework. By combining the catalytic, electronic or cytotoxic properties of selected transition metal complexes with the binding and electronic properties of porphyrins, enhanced characteristics of the ensemble are generated. This review article focuses on porphyrins bearing one or more peripheral transition metal complexes and discusses their potential applications in catalysis or biomedicine. Modulation of the electronic properties and intramolecular communication through coordination bond linkages in bis‐porphyrin scaffolds is also presented. See the future of porphyrin‐metal conjugates: Appending transition metal complexes to the periphery of porphyrins, renowned for their photo‐ and electro‐activity, opens new avenues for applications in electron‐ or photon‐triggered catalytic reactions, optoelectronic properties of self‐assembled materials, and therapeutic or diagnostic tools in biomedicine. [ABSTRACT FROM AUTHOR]

A porphyrin bearing four imidazolium rings on the meso positions was used as an N-heterocyclic carbene (NHC) precursor for the synthesis of porphyrin dimers with face-to-face orientations. The porphyrins are connected through the formation of eight M–CNHC bonds, with M = AgI or AuI. [ABSTRACT FROM AUTHOR]

Abstract: Periodic mesoporous organosilica nanoparticles emerge as promising vectors for nanomedicine applications. Their properties are very different from those of well‐known mesoporous silica nanoparticles as there is no silica source for their synthesis. So far, they have only been synthesized from small bis‐silylated organic precursors. However, no studies employing large stimuli‐responsive precursors have been reported on such hybrid systems yet. Here, the synthesis of porphyrin‐based organosilica nanoparticles from a large octasilylated metalated porphyrin precursor is described for applications in near‐infrared two‐photon‐triggered spatiotemporal theranostics. The nanoparticles display unique interconnected large cavities of 10–80 nm. The framework of the nanoparticles is constituted with J‐aggregates of porphyrins, which endows them with two‐photon sensitivity. The nanoparticle efficiency for intracellular tracking is first demonstrated by the in vitro near‐infrared imaging of breast cancer cells. After functionalization of the nanoparticles with aminopropyltriethoxysilane, two‐photon‐excited photodynamic therapy in zebrafish is successfully achieved. Two‐photon photochemical internalization in cancer cells of the nanoparticles loaded with siRNA is also performed for the first time. Furthermore, siRNA targeting green fluorescent protein complexed with the nanoparticles is delivered in vivo in zebrafish embryos, which demonstrates the versatility of the nanovectors for biomedical applications. [ABSTRACT FROM AUTHOR]

Cage compounds are very attractive structures for a wide range of applications and there is ongoing interest in finding effective ways to access such kinds of complex structures, particularly those possessing dynamic adaptive features. Here we report the accessible synthesis of new type of organic cage architectures, possessing two different dynamic bonds within one structure: hydrazones and disulfides. Implementation of three distinct functional groups (thiols, aldehydes and hydrazides) in the structure of two simple building blocks resulted in their spontaneous and selective self-assembly into aromatic cage-type architectures. These organic cages contain up to ten components linked together by twelve reversible covalent bonds. The advantage provided by the presented approach is that these cage structures can adaptively self-sort from a complex virtual mixture of polymers or macrocycles and that dynamic covalent chemistry enables their deliberate disassembly through controlled component exchange. [ABSTRACT FROM AUTHOR]

For the first time, POSS-based coordination polymers (CPs) have been structurally characterized. These CPs were obtained in high yield via self-assembly reactions of thioether-functionalized polysilsesquioxanes with CuI salts under mild conditions. Single crystal analyses revealed the formation of 3D networks incorporating different secondary building units (SBUs) as connection nodes. The nature of the -SAr functionality allows a fine-tuning of the cluster nuclearity, that is, butterfly-shaped Cu2X2 or closed cubane-type Cu4I4 cores. As such, the resulting hybrid materials exhibit a combination of high thermal stability arising from the inorganic POSS core along with interesting luminescent properties conferred by the cubane cluster core. Furthermore, the occurrence of channels has been shown crystallographically in the case of the Cu4I4 cluster containing CP. [ABSTRACT FROM AUTHOR]

Porphyrins fused to imidazolium salts across two neighboring β-pyrrolic positions were used as N-heterocyclic carbene (NHC) precursors to anchor AuI-Cl complexes at their periphery. Synthesis of several thiolato-AuI complexes was then achieved by substituting chloride for thiolates. Photodynamic properties of these complexes were investigated: the data obtained show that the Au−S bonds could be cleaved upon irradiation. The proposed mechanism to explain the release of thiolate moiety involves the S atom oxidation by singlet oxygen generated in the course of irradiation. In view of photodynamic therapy (PDT) applications, these porphyrins fused to NHC-AuI complexes were tested as photosensitizers to kill MCF-7 breast cancer cells. Results show the important role played by the ancillary ligands (chloride versus thiolates) on the photodynamic effect. [ABSTRACT FROM AUTHOR]

In the past two decades, bulk heterojunction organic photovoltaic (OPV) devices have emerged as attractive candidates for solar energy conversion due to their lightweight design and potential for low-cost, high-throughput, solution-phase processability. Interfacial engineering is a proven efficient approach to achieve OPV devices with high power conversion efficiencies. This mini-review provides an overview of the key structural considerations necessary when undertaking the molecular design of conjugated polyelectrolytes, for application as interfacial layers (ILs). The different roles of ILs are outlined, together with the advantages and disadvantages of competing classes of IL materials. Particular emphasis is placed on the design and synthesis of water-soluble polythiophene-based IL materials and the influence of their structural characteristics on their performance as a promising class of IL material. Finally, the challenges and opportunities for polythiophenes as IL materials for OPV devices and other solution-processed solar cell technologies (e.g. perovskite solar cells) are discussed. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Background: Genomic selection (GS) uses information from genomic signatures consisting of thousands of genetic markers to predict complex traits. As such, GS represents a promising approach to accelerate tree breeding, which is especially relevant for the genetic improvement of boreal conifers characterized by long breeding cycles. In the present study, we tested GS in an advanced-breeding population of the boreal black spruce (Picea mariana [Mill.] BSP) for growth and wood quality traits, and concurrently examined factors affecting GS model accuracy. Results: The study relied on 734 25-year-old trees belonging to 34 full-sib families derived from 27 parents and that were established on two contrasting sites. Genomic profiles were obtained from 4993 Single Nucleotide Polymorphisms (SNPs) representative of as many gene loci distributed among the 12 linkage groups common to spruce. GS models were obtained for four growth and wood traits. Validation using independent sets of trees showed that GS model accuracy was high, related to trait heritability and equivalent to that of conventional pedigree-based models. In forward selection, gains per unit of time were three times higher with the GS approach than with conventional selection. In addition, models were also accurate across sites, indicating little genotype-by-environment interaction in the area investigated. Using information from half-sibs instead of full-sibs led to a significant reduction in model accuracy, indicating that the inclusion of relatedness in the model contributed to its higher accuracies. About 500 to 1000 markers were sufficient to obtain GS model accuracy almost equivalent to that obtained with all markers, whether they were well spread across the genome or from a single linkage group, further confirming the implication of relatedness and potential longrange linkage disequilibrium (LD) in the high accuracy estimates obtained. Only slightly higher model accuracy was obtained when using marker subsets that were identified to carry large effects, indicating a minor role for short-range LD in this population. Conclusions: This study supports the integration of GS models in advanced-generation tree breeding programs, given that high genomic prediction accuracy was obtained with a relatively small number of markers due to high relatedness and family structure in the population. In boreal spruce breeding programs and similar ones with long breeding cycles, much larger gain per unit of time can be obtained from genomic selection at an early age than by the conventional approach. GS thus appears highly profitable, especially in the context of forward selection in species which are amenable to mass vegetative propagation of selected stock, such as spruces. [ABSTRACT FROM AUTHOR]