Borazino-doped polyphenylenes

The divergent synthesis of two series of borazino-doped polyphenylenes, in which one or more aryl units are replaced by borazine rings, is reported for the first time, taking advantage of the decarbonylative [4 + 2] Diels− Alder cycloaddition reaction between ethynyl and tetraphenylcyclopentadienone derivatives. Because of the possibility of functionalizing the borazine core with different groups on the aryl substituents at the N and B atoms of the borazino core, we have prepared borazino-doped polyphenylenes featuring different doping dosages and orientations. To achieve this, two molecular modules were prepared: a core and a branching unit. Depending on the chemical natures of the central aromatic module and the reactive group, each covalent combination of the modules yields one exclusive doping pattern. By means of this approach, three- and hexa-branched hybrid polyphenylenes featuring controlled orientations and dosages of the doping B3N3 rings have been prepared. Detailed photophysical investigations showed that as the doping dosage is increased, the strong luminescent signal is progressively reduced. This suggests that the presence of the B3N3 rings engages additional deactivation pathways, possibly involving excited states with an increasing charge-separated character that are restricted in the full-carbon analogues. Notably, a strong effect of the orientational doping on the fluorescence quantum yield was observed for those hybrid polyphenylene structures featuring low doping dosages. Finally, we showed that Cu-catalyzed 1,3-dipolar cycloaddition is also chemically compatible with the BN core, further endorsing the inorganic benzene as a versatile aromatic scaffold for engineering of molecular materials with tailored and exploitable optoelectronic properties

Unprecedented incorporation of α-emitter radioisotope 213Bi into porphyrin chelates with reference to a daughter isotope mediated assistance mechanism.

International audienceFor the first time, α-emitter radioisotope (213)Bi has been incorporated into porphyrin chelates, with rates matching with the short period of the radionuclide. An in situ transmetalation mechanism involving the daughter isotope (209)Pb is expected to boost the (213)Bi radiolabeling process

Unprecedented Incorporation of alpha-Emitter Radioisotope 213Bi into Porphyrin Chelates with Reference to a Daughter Isotope Mediated Assistance Mechanism

For the first time, alphaemitter radioisotope 213Bi has been 10 incorporated into porphyrin chelates, with rates matching with the short period of the radionuclide. An in-situ transmetalation mechanism involving the daughter isotope 209Pb is expected to boost the 213Bi radiolabeling process.JRC.E.5-Nuclear chemistr

Structural analysis of a dimeric trinuclear zinc(II) complex based on a preorganized yet flexible strap porphyrin

International audienceWe report the solid-state structure of an unexpected trinuclear zinc dimeric porphyrin complex resulting of zinc insertion into a single strap porphyrin. The latter bears an overhanging carboxylic acid which usually interacts with metal cations either in out-of-plane (OOP) or in hanging-atop (HAT) coordination mode by changing its location above the porphyrin coordination site. However, in the present studies, the overhanging carboxylic group acts as a bidentate ligand and binds the OOP-bound zinc cation together with another zinc cation bridging two porphyrin units

Élaboration de nouveaux chélates pour l'alpha-radioimmunothérapie (influence de l'habillage du macrocycle porphyrinique sur la sélectivité plomb / bismuth)

Au cours de ce travail, nous avons développé des agents chélatants intéressants de type macrocycles porphyriniques à acides suspendus destinés à la complexation des radioisotopes a-émetteurs ( Bi, Pb/ Bi) pour une application en alpha radioimmunothérapie, et spécialement en générateur Pb/ Bi in vivo. Ils sont capables de complexer le plomb et le bismuth avec une cinétique rapide et une nucléarité contrôlée. L'élaboration de chélates bifonctionnels et hydrosolubles basée sur ces structures optimisées a été décrite, les complexes obtenus présentent une bonne stabilité en milieu fortement acide ainsi qu'en milieu de culture cellulaire, sans toxicité intrinsèque. La chimie de coordination de bismuth est liée à celle du plomb: le Pb est un isotope fils de Bi, il est inévitablement présent dans l'éluat du générateur, et le Pb est l'isotope parent du Bi, une transmétallation Pb->Bi avec ces chélates a été envisagée, elle consiste à une complexation compétitive entre les deux ions métalliques Pb(II) et Bi(III), cela révèle un effet inédit du plomb qui catalyse l'insertion du bismuth au sein de ces chélates porphyriniques par un mécanisme de transmétallation stéréocontrôlée. Ceci nous laisse entrevoir une synergie entre les radioisotopes parents et fils ( Bi/ Pb) quant à leur complexation. Ce mémoire décrit également la première étude réussie d'incorporation de Bi au sein du macrocycle porphyrinique, ainsi que la transposition des propriétés de coordination en milieu radioactif (cinétique, transmétallation Pb->Bi). Sur le plan fondamental, un nouveau mode de reconnaissance original du plomb et du bismuth qualifié de hanging-atop (HAT), a été mis en évidence conduisant à des systèmes hétérodinucléaires dérivés des porphyrines ditopiques via des processus allostériques. Ceci a révélé un mécanisme de translocation couplé à une transmétallation par laquelle ces systèmes ont ainsi été conçus.This monograph describes the synthesis of a strapped porphyrin ligands bearing overhanging carboxylate groups for the complexation of a-emitter radioisotopes ( Bi, Pb/ Bi) for target radioimmunotherapy application, especially with the in vivo generator Pb/ Bi. They are able to complex both lead and bismuth cations with fast kinetic and a controlled nuclearity. A bifunctional and a water-soluble porphyrin macrocyle based on these optimized structures have been synthesized. The resulting complexes exhibit a good stability under strongly acidic conditions and in cell culture medium without inherent toxicity. The coordination chemistry of bismuth is related to that of lead: 209Pb is a daughter isotope of 213Bi, it is inevitably present in the eluate from the generator, and Pb is the parent isotope of Bi. Transmetalation Pb ->Bi approach was first considered, it consists to a competitive complexation between Pb(II) and Bi(III) cations, this reveals an original lead effect that catalyses the insertion of bismuth in these porphyrin chelates via a stereocontrolled transmetallation mechanism. An in situ synergy between the daughter and father isotope Pb/ Bi is expected to boost the Bi radiolabeling process. In this work, we describe also the first successful incorporation of a-emitter radioisotope Bi into porphyrin chelates, as well as the transposition of coordination properties in a radioactive environment (kinetic transmetallation Pb -> Bi). Theoretically, we have described the formation of a bimetallic porphyrin complexes based on an original so-called hangin-atop (HAT) coordination mode of lead(II) and bismuth(III) cations via an allosteric process. An unprecedented translocation-coupled transmetallation mechanism is at the origin the formation of these systems.RENNES1-BU Sciences Philo (352382102) / SudocSudocFranceF

Metal migration processes in homo- and heterobimetallic bismuth(III)-lead(II) porphyrin complexes: emergence of allosteric Newton's cradle-like devices.

International audienceMetal ion migration in a bis-strapped porphyrin ligand with overhanging carboxylate groups has been investigated in solution. Two types of homobimetallic complexes are generated with Pb(II) and Bi(III) cations, which stand on both sides of the macrocycle: (i) a dissymmetric complex with one cation bound to the porphyrin N core and the other cation hung over the N core through bonding with a carboxylate of a strap; (ii) a C(2)-symmetric complex with both cations coordinated to the N core and to the carboxylate groups of the straps. Variable-temperature NMR studies and 2D rotational Overhauser effect spectroscopy NMR experiments have shown that in the former dissymmetric complexes, the two cations undergo a coupled intramolecular migration resulting in exchange of their coordination modes. Such complexes constitute active states of Newton's cradle-like devices (NCDs), with the ion migration rate depending on the lability of the metal-ligand interactions [Pb(II) faster than Bi(III) NCDs]. On the other hand, the C(2)-symmetric complexes constitute either an inactive state [with Pb(II)] or a resting state [with Bi(III)] of an NCD, since they correspond respectively to a precursor or an intermediate in the motion of the cations. The NCDs are under both allosteric and acid-base control: (i) with Pb(II), the addition of an allosteric effector such as an acetate anion to the medium allows the conversion of the symmetric form to the dissymmetric one, thus triggering the Newton's cradle-like motion of the cations; (ii) with Bi(III), a lifted state was converted to a resting one by the addition of protons and then restored by the addition of a base. As an extension to nondegenerate systems, a heterobimetallic Bi(III)-Pb(II) complex was selectively obtained, and it constitutes a frozen lifted state of a dissymmetric NCD. All of these homo- and hetero-NCDs could be successively formed by selective metal ion exchange. These unique findings open the way to novel tristable devices

Functionalization of porphyrins: towards the synthesis of bifunctional chelates for bismuth coordination

International audienceWe report the condensation of 3-chloromethyl-benzoyl chloride with two atropisomers ααββ and αβαβ of meso-5,10,15,20-tetrakis-(2-amino)phenylporphyrin (TAPP), followed by the reaction of the anion of either cyano-acetic acid ethyl ester or (4-nitro-phenyl)-acetic acid ethyl ester to prepare various pre-organized strapped porphyrins. These two reagents were selected as both allow the easy formation of the anion in the α position of the ester group while their electron-withdrawing group (EWG) can be further transformed in a reactive functional group. In the ααββ series, this reaction leads to three isomeric porphyrins differing only by the location of their ethoxycarbonyl groups, oriented either towards the center of the porphyrin or maintained outside of the cavity. In the αβαβ series, as expected, a single porphyrin is obtained in which both straps bear an ethoxycarbonyl group, precursor of a hanging carboxylic function and a cyano or a 4-nitro-phenyl group, which can be reduced to an amine function, suitable for the coupling on a biomolecule

N-Heterocyclic Carbene Coinage Metal Complexes Containing Naphthalimide Chromophore: Design, Structure, and Photophysical Properties

A series of novel N-heterocyclic carbene coinage metal complexes containing a naphthalimide (NI) chromophore has been prepared and fully characterized. Two types of molecules are described those where the NI unit is directly attached to the carbene unit with the general formulae [(L1)–M–X], M = Cu, X = Cl (1a); M = Ag, X = I (1b) and M = Au, X = Cl, (1c). While in the second family, a π-extended carbene ligand precursor L2–H+I− (3) was prepared where the NI unit is distant from the imidazole unit via a phenyl-alkyne bridge. Only two N-heterocyclic carbene metal complexes were prepared [(L2)–M–Cl], M = Cu (2a) and M = Au (2c). The related silver carbene compound could not be isolated. The molecular structure of the carbene complex 1c was determined and confirmed the formation of the target compound. Interestingly, the structure shows the presence of an aurophilic interaction Au···Au at 3.407 Å between two individual molecules. The photophysical properties of the compounds were investigated in solution at room temperature. Preliminary results suggested that all compounds are luminescent and act as blue emitters (420–451 nm). These transition emissions can be attributed to the intraligand origin of the NI chromphore. Moreover, the carbene complexes featuring L2 ligand with π-extended system were found to be more luminescent

Metal Migration Processes in Homo- and Heterobimetallic Bismuth(III)–Lead(II) Porphyrin Complexes: Emergence of Allosteric Newton’s Cradle-like Devices

Metal ion migration in a bis-strapped porphyrin ligand with overhanging carboxylate groups has been investigated in solution. Two types of homobimetallic complexes are generated with Pb­(II) and Bi­(III) cations, which stand on both sides of the macrocycle: (i) a dissymmetric complex with one cation bound to the porphyrin N core and the other cation hung over the N core through bonding with a carboxylate of a strap; (ii) a <i>C</i>₂-symmetric complex with both cations coordinated to the N core and to the carboxylate groups of the straps. Variable-temperature NMR studies and 2D rotational Overhauser effect spectroscopy NMR experiments have shown that in the former dissymmetric complexes, the two cations undergo a coupled intramolecular migration resulting in exchange of their coordination modes. Such complexes constitute active states of <i>Newton’s cradle-like devices</i> (NCDs), with the ion migration rate depending on the lability of the metal–ligand interactions [Pb­(II) faster than Bi­(III) NCDs]. On the other hand, the <i>C</i>₂-symmetric complexes constitute either an inactive state [with Pb­(II)] or a resting state [with Bi­(III)] of an NCD, since they correspond respectively to a precursor or an intermediate in the motion of the cations. The NCDs are under both allosteric and acid–base control: (i) with Pb­(II), the addition of an allosteric effector such as an acetate anion to the medium allows the conversion of the symmetric form to the dissymmetric one, thus triggering the Newton’s cradle-like motion of the cations; (ii) with Bi­(III), a lifted state was converted to a resting one by the addition of protons and then restored by the addition of a base. As an extension to nondegenerate systems, a heterobimetallic Bi­(III)–Pb­(II) complex was selectively obtained, and it constitutes a frozen lifted state of a dissymmetric NCD. All of these homo- and hetero-NCDs could be successively formed by selective metal ion exchange. These unique findings open the way to novel tristable devices