A strong steric hindrance effect on ground state, excited state, and charge separated state properties of a Cu(I)-diimine complex captured by X-ray transient absorption spectroscopy.

Photophysical and structural properties of a Cu(I) diimine complex with very strong steric hindrance, [Cu(I)(dppS)2](+) (dppS = 2,9-diphenyl-1,10-phenanthroline disulfonic acid disodium salt), are investigated by optical and X-ray transient absorption (OTA and XTA) spectroscopy. The bulky phenylsulfonic acid groups at 2,9 positions of phenanthroline ligands force the ground state and the metal-to-ligand charge-transfer (MLCT) excited state to adopt a flattened pseudo-tetrahedral coordination geometry in which the solvent access to the copper center is completely blocked. We analyzed the MLCT state dynamics and structures as well as those of the charge separated state resulting from the interfacial electron injection from the MLCT state to TiO2 nanoparticles (NPs). The OTA results show the absence of the sub-picosecond component previously assigned as the time constant for flattening, while the two observed time constants are assigned to a relatively slow intersystem crossing (ISC) rate (∼13.8 ps) and a decay rate (100 ns) of the [Cu(I)(dppS)2](+) MLCT state in water. These results correlate well with the XTA studies that resolved a flattened tetrahedral Cu(i) coordination geometry in the ground state. Probing the (3)MLCT state structure with XTA establishes that the (3)MLCT state has the same oxidation state as the copper center in [Cu(II)(dppS)2](2+) and the Cu-N distance is reduced by 0.06 Šcompared to that of the ground state, accompanied by a rotation of phenyl rings located at 2,9 positions of phenanthroline. The structural dynamics of the photoinduced charge transfer process in the [Cu(I)(dppS)2](+)/TiO2 hybrid is also investigated, which suggests a more restricted environment for the complex upon binding to TiO2 NPs. Moreover, the Cu-N bond length of the oxidized state of [Cu(I)(dppS)2](+) after electron injection to TiO2 NPs shortens by 0.05 Šcompared to that in the ground state. The interpretation of these observed structural changes associated with excited and charge separated states will be discussed. These results not only set an example for applying XTA in capturing the intermediate structure of metal complex/semiconductor NP hybrids but also provide guidance for designing efficient Cu(I) diimine complexes with optimized structures for application in solar-to-electricity conversion.

[Ophthalmic arteries originating from external carotid arteries]. / Artères ophtalmiques issues des carotides externes. A propos d'un cas.

The ophthalmic artery arises from the internal carotid at the level of the carotid siphon; in 3.5-5% of the population, it arises from the middle meningeal artery, a branch of the internal maxillary artery, terminal of the external carotid artery. We report a rare case of bilateral malformation in a 28-year-old patient. Our study covers the possible dual origin of orbital blood vascularization. This variation in the anatomic distribution is important to know, particularly if embolization is intended as inadvertent occlusion of the ophthalmic artery, because it may lead to permanent loss of vision.

[Granulocytic sarcoma in a 90-year-old patient]. / Sarcome granulocytaire (chlorome) chez un patient âgé de 90 ans.

Granulocytic sarcoma rarely involves the orbit. It is the local proliferation of immature myeloid cells and occurs most often in patients suffering from myelodysplastic syndromes. We report a case of granulocytic sarcoma that revealed acute myeloid leukemia in a patient suffering from chronic myelomonocytic leukemia. At the time of diagnosis, the lesion involved the nasal fossae, the ethmoidal sinus, and the orbit, with subperiosteal tumoral infiltration toward the skin. The treatment involved surgery and radiotherapy. The patient died 3 months later of complications of the hematological disease. This observation is original for the occurrence of granulocytic sarcoma during chronic and well-known leukemia, the age of onset, and the fatal outcome in just a few weeks. In this observation, the ophthalmologist revealed the acute nature of the myelodysplastic syndrome.

Irreversible but noncovalent Ru(II)-pyridine bond: its use for the formation of [2]-catenanes.

The reaction between ligand 1, which consists of two terminal pyridines attached to a central 1,10-phenanthroline (phen), and the complex Ru(phen)2(CH3CN)2(PF6)2 has been studied. A new ruthenium containing metallamacrocycle has been obtained and fully characterized. Despite the relatively poor yield for the cyclization process involving the ruthenium center (20%), this strategy led to the synthesis of two different kinds of [2]-catenane. The first example reported in this article is a bimetallic Cu(I)/Ru(II) catenane 5(3+) consisting of a purely organic ring interlocked with the ruthenium(II)-incorporating metallacycle. Complex 5(3+) was selectively demetalated at the Cu(I) center to lead to the free Ru(II)-containing catenane. A trimetallic Ru(II)/Cu(I)/Ru(II) catenane 8(5+) was also synthesized showing that this approach is reliable and promising for the elaboration of photoactive multicomponent systems.

A linear multiporphyrinic

A linear multiporphyrinic [2]-rotaxane has been synthesized using the transition metal-templating method for threading a gold(III)-incorporating macrocycle onto a rodlike, phenanthroline-derived chelate bearing carboxylate end groups. Stoppering has been performed by reacting the resulting prerotaxane with the amino derivative of a zinc tetraarylporphyrin under EDC-HOBt activation. A 34% yield has been realized for this one-pot, double amide bond formation.

Chiroptical properties of an optically pure dicopper(I) trefoil knot and its enantioselectivity in luminescence quenching reactions

Chiroptical spectroscopy is used to investigate the properties of an optically pure dinuclear copper(I) trefoil knot. For the metal-to-ligand charge tranfer (MLCT) transition in the visible region (520 nm), the electric and magnetic transition dipole moments are determined from absorption and circular dichroism spectra: 2.8 Debye and 0.5 Bohr magneton (muB). Circular polarization in the luminescence (CPL) of the knot is determined and this allows the electric and magnetic transition dipole moments in emission to be calculated: 0.02 Debye and 0.003 muB. The large difference between the moments in absorption and emission shows that the emission observed does not originate directly from the 1MLCT state. Given the low probability for radiative decay we assign the long-lived emitting excited state to a 3MLCT state. The copper(I) trefoil knot is found to quench the emission from TbIII and EuIII(dpa)3(3)-(dpa = pyridine-2,6-dicarboxylate) with a bimolecular rate constant of 3.2 and 3.3 x 10(7)M(-1)S(-1), respectively, at room temperature in water-acetonitrile (1:1 by volume). Experimental results indicate that the (lambda)-knot preferentially quenches the lambda enantiomer of the lanthanide complex with an enantioselectivity (ratio of quenching rate constants for lambda and lambda: kqlambda/kqdelta) of 1.012+/-0.002 for EuIII and 1.0180+/-0.003 for TbIII.

Synthesis of Copper(I) catenanes incorporating a disulfide bridge and their deposition on a gold surface

The synthesis of two coordinating catenates with the ability to undergo surface-confined chemistry is described. For each catenate, one of the rings includes a 2,9-diphenyl-1,10-phenanthroline unit as a coordinating moiety and a disulfide bridge, which allows adsorption of the catenate onto a gold surface, thus going from a molecular catenate to a [gold-adsorbed] species in which gold atoms are elements of one of the rings.

Pi-conjugated ligand polymers entwined around copper centres

We describe conjugated polymers entwined around Cu1 with alternating alpha-quaterthienyl (poly[Cu(T2)2]) or 3',4',3'''',4''''-tetrahexyl-alpha-sexythienyl (poly[Cu(T3)2]) moieties and 1,10-phenanthroline complexing sites. Our strategy is to synthesise the 2,9-bis(oligothienyl)-1,10-phenanthroline precursors, then to assemble these ligands by means of Cu1 templating followed by electropolymerisation. Poly[Cu(T2)2] shows separate electroactivities for Cu redox centres and conjugated backbones, whereas the electroactivities overlap in the case of poly[Cu(T3)2]. An X-ray absorption study on these polymers in their reduced state at the Cu-K edge identifies, in both cases, four nitrogen atoms as the closest copper(I) neighbours. For poly[Cu(T2)2], the Cu1 environment is a distorted tetrahedron similar to a monomer model compound, but with a slightly higher number of steric constraints. The Cu1 environment for poly[Cu(T3)2] is a less distorted tetrahedron with an unusually short Cu1-N average bond length. Cu1 removal in poly[Cu(T2)2] induces an irreversible collapse of the structure, whereas the reversibility of Cu1 binding is almost perfect for poly[Cu(T3)2], as the hexyl chains prevent irreversible gliding of the wires after copper removal. Combined electrochemical and resistance measurements reveal that the Cu centres in poly[Cu(T2)2] play the role of mechanical support for the structure with no significant electronic interactions with the conjugated backbone, whereas in the case of poly[Cu(T3)2] copper centres contribute to the conductivity of the structure.