Energy exchange between Nd and Er centers within molecular complexes.

Developing controlled and reproducible molecular assemblies incorporating lanthanide centers is a crucial step for driving forward up- and down-conversion processes. This challenge calls for the development of strategies to facilitate the efficient segregation of different Ln metal ions into distinct positions within the molecule. The unique family of pure [LnLn'Ln] heterometallic coordination compounds previously developed by us represents an ideal platform for studying the desired Ln-to-Ln' energy transfer (ET).

Temperature-dependent NIR-CPL spectra of chiral Yb(III) complexes.

Chiral, enantiopure Yb(III) complexes exhibit circularly polarized luminescence (CPL) in the near infrared (NIR) wavelength region. This CPL is quantified by the dissymmetry factor (). The excited state F consists of six m states degenerated in three Stark levels, due to the crystal-field splitting (CFS), which are populated in accordance with the Boltzmann distribution.

Influence of Chemical Modifications of the Crystallophore on Protein Nucleating Properties and Supramolecular Interactions Network.

Crystallophores are lanthanide complexes that have demonstrated outstanding induction of crystallization for various proteins. This article explores the effect of tailored modifications of the crystallophore first generation and their impact on the nucleating properties and protein crystal structures. Through high-throughput crystallization experiments and dataset analysis, we evaluated the effectiveness of these variants, in comparison to the first crystallophore generation G.

One touch is all it takes: the supramolecular interaction between ubiquitin and lanthanide complexes revisited by paramagnetic NMR and molecular dynamics.

The supramolecular interaction between lanthanide complexes and proteins is at the heart of numerous chemical and biological studies. Some of these complexes have demonstrated remarkable interaction properties with proteins or peptides in solution and in the crystalline state. Here we have used the paramagnetism of lanthanide ions to characterize the affinity of two lanthanide complexes for ubiquitin.

Theoretical and experimental analysis of circularly polarized luminescence spectrophotometers for artifact-free measurements using a single CCD camera.

Circularly polarized luminescence (CPL) is a fast growing research field as a complementary chiroptical spectroscopy alternative to the conventional circular dichroism or in the quest of devices producing circularly polarized light for different applications. Because chiroptical signals are generally lower than 0.1%, conventional chiral spectroscopies rely on polarization time modulation requiring step-by-step wavelength scanning and a long acquisition time.

Distributive Nd-to-Yb Energy Transfer within Pure [YbNdYb] Heterometallic Molecules.

Facile access to site-selective hetero-lanthanide molecules will open new avenues in the search of novel photophysical phenomena based on Ln-to-Ln' energy transfer (ET). This challenge demands strategies to segregate efficiently different Ln metal ions among different positions in a molecule. We report here the one-step synthesis and structure of a pure [YbNdYb] () coordination complex featuring short Yb···Nd distances, ideal to investigate a potential distributive (, from one donor to two acceptors) intramolecular ET from one Nd ion to two Yb centers within a well-characterized molecule.

Ytterbium(III) Complex with Photochromic Ruthenium(II) Acetylide Ligand: All Visible Light Photoswitching of NIR Luminescence.

We report a ruthenium(II) bisacetylide complex bearing a photochromic dithienylethene (DTE) acetylide arm and a coordinating bipyridyl on the acetylide unit. Its coordination with Yb(TTA) centers (TTA = 2-thenoyltrifluoroacetonate) produces a bimetallic complex in which the dithienylethene isomerization is triggered by both ultraviolet (UV) light absorbed by the DTE unit and 450 nm excitation in a transition of the organometallic moiety. The redox behavior arising from the ruthenium(II) bisacetylide system is fully investigated by cyclic voltammetry and spectroelectrochemistry, revealing a lack of stability of the DTE-closed oxidized state preventing effective redox luminescence switching.

Multifunctional Helicene-Based Ytterbium Coordination Polymer Displaying Circularly Polarized Luminescence, Slow Magnetic Relaxation and Room Temperature Magneto-Chiral Dichroism.

The combination of physical properties sensitive to molecular chirality in a single system allows the observation of fascinating phenomena such as magneto-chiral dichroism (MChD) and circularly polarized luminescence (CPL) having potential applications for optical data readout and display technology. Homochiral monodimensional coordination polymers of Yb were designed from a 2,15-bis-ethynyl-hexahelicenic scaffold decorated with two terminal 4-pyridyl units. Thanks to the coordination of the chiral organic chromophore to Yb(hfac) units (hfac =1,1,1,5,5,5-hexafluoroacetylaconate), efficient NIR-CPL activity is observed.

Modulation of the magnetic and photophysical properties in 3d-4f and 4f-4f' heterobimetallic complexes involving a tetrathiafulvalene-based ligand.

The reaction between the 2-(1-(2,6-di(pyrazol-1-yl)-4-methylpyridyl)-4,5-(4,5-bis(propylthio)-tetrathiafulvalenyl)-1-benzimidazol-2-yl)-pyridine ligand (L), 1 equivalent of Ln(hfac)·2HO/Dy(tta)·2HO (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonate, tta = 2-thenoyltrifluoroacetonate) and M(hfac)·2HO leads to the formation of heteroleptic 3d-4f dinuclear complexes of formula [MLn(hfac)(L)] (M(II) = Cd, Zn, Co, Mn, Ni and Ln(III) = Dy, Yb, Nd) and [ZnDy(tta)(hfac)(L)]·(CHCl). Their X-ray structures reveal that the two coordination sites are occupied by one Ln(III) ion and one M(II) transition metal respectively. The M(II) ions are coordinated to the benzoimidazolylpyridine (bzip) moiety in a NO coordination sphere, while the Ln(III) ions are coordinated to the 2,6-di(pyrazol-1-yl)-4-pyridine (dpp) moiety in a NO surrounding.

De novo determination of mosquitocidal Cry11Aa and Cry11Ba structures from naturally-occurring nanocrystals.

Cry11Aa and Cry11Ba are the two most potent toxins produced by mosquitocidal Bacillus thuringiensis subsp. israelensis and jegathesan, respectively. The toxins naturally crystallize within the host; however, the crystals are too small for structure determination at synchrotron sources.

Synthesis and Photophysical Properties of 1,1,4,4-Tetracyanobutadienes Derived from Ynamides Bearing Fluorophores.

1,1,4,4-Tetracyanobutadienes (TCBDs) bearing a large diversity of fluorophores were prepared following a multi-step synthesis. In a crucial last step, all compounds were obtained from the corresponding ynamides, which were particularly suitable for the formation of the TCBDs in the presence of tetracyanoethylene via a [2+2] cycloaddition/retroelectrocyclization step (CA-RE). Several fluorenyl derivatives in addition to phenanthrenyl and terphenyl ones provided ynamide-based TCBDs affording remarkable emission properties covering a large range of wavelengths.

Circularly polarized luminescence of Eu(III) complexes with chiral 1,1'-bi-2-naphtol-derived bisphosphate ligands.

The interest for lanthanide circularly polarized luminescence (CPL) has been quickly growing for 10 years. However, very few of these studies have involved correlation between the dissymmetry factor (g ) and the chemical modifications in a series of chiral ligands. Four polymeric compounds of Eu(III) were prepared by using a series of binaphtyl derivatives for which the size of the π system as well as the number of stereogenic elements (i.

Tuning Excited-State Properties of [2.2]Paracyclophane-Based Antennas to Ensure Efficient Sensitization of Lanthanide Ions or Singlet Oxygen Generation.

The multistep synthesis of original antennas incorporating substituted [2.2]paracyclophane (pCp) moieties in the π-conjugated skeleton is described. These antennas, functionalized with an electron donor alkoxy fragment () or with a fused coumarin derivative (), are incorporated in a triazacyclonane macrocyclic ligand or , respectively, for the design of Eu(III), Yb(III), and Gd(III) complexes.

Influence of Divalent Cations in the Protein Crystallization Process Assisted by Lanthanide-Based Additives.

The use of lanthanide complexes as powerful auxiliaries for biocrystallography prompted us to systematically analyze the influence of the commercial crystallization kit composition on the efficiency of two lanthanide additives: [Eu(DPA)] and Tb-Xo4. This study reveals that the tris(dipicolinate) complex presents a lower chemical stability and a strong tendency toward false positives, which are detrimental for its use in a high-throughput robotized crystallization platform. In particular, the crystal structures of (Mg(HO))[Eu(DPA)]·7HO (), {(Ca(HO))[Eu(DPA)]}·10HO (), and {Cu(DPA)(HO)} (), resulting from spontaneous crystallization in the presence of a divalent alkaline-earth cation and transmetalation, are reported.

Capturing the dynamic association between a tris-dipicolinate lanthanide complex and a decapeptide: a combined paramagnetic NMR and molecular dynamics exploration.

In the realm of biomolecules, peptides can present a large diversity of structures. Our study sheds new light on the structural interplay between a tris-dipicolinate lanthanide probe and a decapeptide SASYKTLPRG. Although a rather trivial, electrostatically driven interaction was expected, the combination of paramagnetic NMR and molecular dynamics simulations reveals a highly dynamic association process and allows for providing extensive insights into the interaction sites and their occupancy.

Solid-State Near-Infrared Circularly Polarized Luminescence from Chiral Yb -Single-Molecule Magnet.

A field-induced chiral Yb Single-Molecule Magnet (SMM) displayed an unprecedented near-infrared circularly polarized luminescence (NIR-CPL) in the solid-state. The bridging bis(1,10-phenantro[5,6b])tetrathiafulvalene triad (L) allowed an efficient sensitization of the NIR F → F emission while the NIR-CPL is associated to the f-f transitions of the Yb ion bearing chiral β-diketonate derived-camphorate ancillary ligands.

Cationic Biphotonic Lanthanide Luminescent Bioprobes Based on Functionalized Cross-Bridged Cyclam Macrocycles.

Cationic lanthanide complexes are generally able to spontaneously internalize into living cells. Following our previous works based on a diMe-cyclen framework, a second generation of cationic water-soluble lanthanide complexes based on a constrained cross-bridged cyclam macrocycle functionalized with donor-π-conjugated picolinate antennas was prepared with europium(III) and ytterbium(III). Their spectroscopic properties were thoroughly investigated in various solvents and rationalized with the help of DFT calculations.

Redox-Modulations of Photophysical and Single-molecule Magnet Properties in Ytterbium Complexes Involving Extended-TTF Triads.

The reaction between the 2,2'-benzene-1,4-diylbis(6-hydroxy-4,7-di--butyl-1,3-benzodithiol-2-ylium-5-olate triad () and the metallo-precursor [Yb(hfac)]2HO led to the formation of a dinuclear coordination complex of formula [Yb(hfac)()]0.5CHCl (). After chemical oxidation of in 2,2'-cyclohexa-2,5-diene-1,4-diylidenebis(4,7-di--butyl-1,3-benzodithiole-5,6-dione (), the latter triad reacted with the [Yb(hfac)]2HO precursor to give the dinuclear complex of formula [Yb(hfac)()] ().

Luminescence-Driven Electronic Structure Determination in a Textbook Dimeric Dy -Based Single-Molecule Magnet.

A textbook dysprosium dinuclear complex based on acetylacetone ligands, [Dy (acac) (μ -acac) (H O) ], has been synthesized and fully characterized. This simple dimeric lanthanide complex shows well-resolved solid-state luminescence and behaves as a single-molecule magnet under zero DC field. A seminal crystal-field approach is used to marry both magnetism and luminescence in the frame of an energetic picture.

Dual Light and Redox Control of NIR Luminescence with Complementary Photochromic and Organometallic Antennae.

With the help of a judicious association between dithienylethene (DTE) units, an ytterbium ion, and a ruthenium carbon-rich complex, we describe (i) the efficient (on/off) switching of pure NIR luminescence with a photochromic unit absorbing in the UV range and (ii) the association of electrochemical and photochemical control of this NIR emission in a single system with nondestructive readout.

Protein crystal structure determination with the crystallophore, a nucleating and phasing agent.

Obtaining crystals and solving the phase problem remain major hurdles encountered by bio-crystallographers in their race to obtain new high-quality structures. Both issues can be overcome by the crystallophore, Tb-Xo4, a lanthanide-based molecular complex with unique nucleating and phasing properties. This article presents examples of new crystallization conditions induced by the presence of Tb-Xo4.

Intriguing Effects of Halogen Substitution on the Photophysical Properties of 2,9-(Bis)halo-Substituted Phenanthrolinecopper(I) Complexes.

Three new copper(I) complexes [Cu(L)](PF) (where L stands for 2,9-dihalo-1,10-phenanthroline and X = Cl, Br, and I) have been synthesized in order to study the impact of halogen substituents tethered in the α position of the chelating nitrogen atoms on their physical properties. The photophysical properties of these new complexes (hereafter named Cu-X) were characterized in both their ground and excited states. Femtosecond ultrafast spectroscopy revealed that early photoinduced processes are faster for Cu-I than for Cu-Cl or Cu-Br, both showing similar behaviors.

The multicatalytic compartment of propionyl-CoA synthase sequesters a toxic metabolite.

Cells must cope with toxic or reactive intermediates formed during metabolism. One coping strategy is to sequester reactions that produce such intermediates within specialized compartments or tunnels connecting different active sites. Here, we show that propionyl-CoA synthase (PCS), an ∼ 400-kDa homodimer, three-domain fusion protein and the key enzyme of the 3-hydroxypropionate bi-cycle for CO fixation, sequesters its reactive intermediate acrylyl-CoA.

Polyanionic Polydentate Europium Complexes as Ultrabright One- or Two-photon Bioprobes.

A family of europium (III) complexes based on a polydentate ligand functionalized by charge-transfer antennae presents remarkable one- and two-photon photophysical proper-ties in water or buffer. A detailed analysis of their emission properties suggests that the wrapping of the ligand around the central rare-earth ion results in an overall Cs symmetry in agreement with the theoretical simulation and that about 65-70 % of the emission intensity is concentrated in the hypersensitive D → F transition at 615 nm. Their brightness is excellent, in the range of the best lanthanide bioprobes making them very attractive for bio-imaging experiments.