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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 in situ 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). In this context, we report here the new pure one-step synthetically produced [ErNdEr] (3) complex, which allows for the first time at the molecular level to study the mechanisms behind Nd-to-Er energy transfer. To further assess the photophysical properties of this complex, the analogous [LuNdLu] (1) and [ErLaEr] (2) complexes have also been prepared and photophysically studied. Efficient sensitization via the two β-diketones employed as main ligands was probed for both Nd 3+ and Er 3+ ions, resulting in highly resolved emission spectra and sufficiently long excited state lifetimes, which allowed further assessment of the Ln-to-Ln' ET. This intermetallic transfer was first detected by comparing the emission spectra of iso-absorbant solutions and demonstrated by comparing the lifetime values with or without the lanthanide quencher (Er 3+ ), as well as with a deep analysis of the excitation spectrum of the three complexes. Thus, a very unique phenomenon was discovered, consisting of a mutual Nd-to-Er and Er-to-Nd ET with no net increase of brightness by any metal; while Nd 3+ transfers the energy received from the antenna to Er 3+ , the sensitization of the latter results in back-transfer to Nd 3+ into a non-emissive, thus silent, state., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

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 1 . In particular, the V 1 variant, featuring a propanol pendant arm, demonstrated the ability to produce new crystallization conditions for the proteins tested (hen-egg white lysozyme, proteinase K and thaumatin). Structural analysis performed in the case of hen egg-white lysozyme along with Molecular Dynamics simulations, highlights V 1 's unique behavior, taking advantage of the flexibility of its propanol arm to explore different protein surfaces and form versatile supramolecular interactions., (© 2024 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.)

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 ( g lum F 2 F 5/2 consists of six m J ' states degenerated in three Stark levels, due to the crystal-field splitting (CFS), which are populated in accordance with the Boltzmann distribution. Consequently, room temperature CPL spectra are the sum of various - either positive or negative - contributions, that are practically impossible to quantify. To address this issue, an advanced setup enabling CPL measurements over a broad temperature range (300 to 4 K) has been developed. The interrelation of CFS, g lum and temperature was explored using a pair of enantiopure Yb(III) complexes, highlighting the individual contribution of each crystal-field sublevel to the overall CPL spectrum, as anticipated by simulations performed in the framework of multireference wave-functions. Hence, the CPL spectra of chiral lanthanide complexes were found to be indeed strongly temperature-dependent, as is the g lum dissymmetry factor, as a consequence of the variation in thermal sublevel population.

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. As the interaction process is dynamic, the acquired NMR data only reflect the time average of the different steps. We have used molecular dynamics (MD) simulations to get a deeper insight into the detailed interaction scenario at the microsecond scale. This NMR/MD approach enabled us to establish that the tris-dipicolinate complex interacts specifically with arginines and lysines, while the crystallophore explores the protein surface through weak interactions with carboxylates. These observations shed new light on the dynamic interaction properties of these complexes, which will ultimately enable us to propose a crystallization mechanism.

Lanthanide ions have attracted great interest owing to their optical and magnetic properties. Single-molecule magnet (SMM) behavior has been a fascinating science for thirty years. Moreover, chiral lanthanide complexes allow the observation of remarkable circularly polarized luminescence (CPL). However, the combination of both SMM and CPL behaviors in a single molecular system is very rare and deserves attention in the design of multifunctional materials. Four chiral one-dimensional coordination compounds involving 1,1'-Bi-2-naphtol (BINOL)-derived bisphosphate ligands and the Yb(iii) centre were synthesized and characterized by powder and single-crystal X-ray diffraction. All the Yb(iii)-based polymers displayed field-induced SMM behavior with magnetic relaxation occurring by applying Raman processes and near infrared CPL in the solid state., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

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. High throughput controls motivated the development of CPL spectrophotometers using cameras as detectors and space polarization splitting. However, CPL measurements imposes careful precautions to minimize the numerous artifacts arising from experimental imperfections. Some previous work used complex calibration procedure to this end. Here we present a rigorous Mueller analysis of an instrument based on polarizations space splitting. We show that by using one camera and combining spatial and temporal separation through two switchable circular polarization encoding arms we can record accurate CPL spectra without the need of any calibration. The measurements robustness and their fast acquisition times are exemplified on different chiral emitters., (© 2023. The Author(s).)

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] ( 1 ) coordination complex featuring short Yb···Nd distances, ideal to investigate a potential distributive ( i.e. , from one donor to two acceptors) intramolecular ET from one Nd 3+ ion to two Yb 3+ centers within a well-characterized molecule. The difference in ionic radius is the mechanism allowing to allocate selectively both types of metal ion within the molecular structure, exploited with the simultaneous use of two β-diketone-type ligands. To assist the photophysical investigation of this heterometallic species, the analogues [YbLaYb] ( 2 ) and [LuNdLu] ( 3 ) have also been prepared. Sensitization of Yb 3+ and Nd 3+ in the last two complexes, respectively, was observed, with remarkably long decay times, facilitating the determination of the Nd-to-Yb ET within the [YbNdYb] composite. This ET was demonstrated by comparing the emission of iso-absorbant solutions of 1 , 2 , and 3 and through lifetime determinations in solution and solid state. The comparatively high efficiency of this process corroborates the facilitating effect of having two acceptors for the nonradiative decay of Nd 3+ created within the [YbNdYb] molecule.

We report a ruthenium(II) bisacetylide complex bearing a photochromic dithienylethene (DTE) acetylide arm and a coordinating bipyridyl on the trans acetylide unit. Its coordination with Yb(TTA) 3 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. On the other hand, the photoswitching of ytterbium(III) near-infrared (NIR) emission triggered by the photochromic reaction is fully operational. The electronic structure of this complex in its different states characterized by strong electronic coupling between the DTE and the ruthenium(II)-based moieties leading to metal-assisted photochromic behavior were rationalized with the help of time-dependent density functional theory (TD-DFT) calculations.

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 III 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) 3 units (hfac - =1,1,1,5,5,5-hexafluoroacetylaconate), efficient NIR-CPL activity is observed. Moreover, the specific crystal field around the Yb III induces a strong magnetic anisotropy which leads to a single-molecule magnet (SMM) behaviour and a remarkable room temperature MChD. The MChD-structural correlation is supported by computational investigations., (© 2022 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

The reaction between the 2-(1-(2,6-di(pyrazol-1-yl)-4-methylpyridyl)-4,5-(4,5-bis(propylthio)-tetrathiafulvalenyl)-1 H -benzimidazol-2-yl)-pyridine ligand (L), 1 equivalent of Ln(hfac) 3 ·2H 2 O/Dy(tta) 3 ·2H 2 O (hfac - = 1,1,1,5,5,5-hexafluoroacetylacetonate, tta - = 2-thenoyltrifluoroacetonate) and M(hfac) 2 ·2H 2 O leads to the formation of heteroleptic 3d-4f dinuclear complexes of formula [MLn(hfac) 5 (L)] n (M(II) = Cd, Zn, Co, Mn, Ni and Ln(III) = Dy, Yb, Nd) and [ZnDy(tta) 2 (hfac) 3 (L)]·(CH 2 Cl 2 ). 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 N 2 O 4 coordination sphere, while the Ln(III) ions are coordinated to the 2,6-di(pyrazol-1-yl)-4-pyridine (dpp) moiety in a N 3 O 6 surrounding. When Dy(III) ion is used a field-induced Single-Molecule Magnet (SMM) behavior is detected with a magnetic relaxation time slightly dependent to the nature of the vicinal divalent transition metal. On the other hand, when the Yb(III) is used, intense, moderated or quenched 2 F 5/2 → 2 F 7/2 NIR luminescence is observed when the Yb(III) ion is respectively associated with the Zn(II), Mn(II) and Ni(II)/Co(II) ion. The emission intensity can be modulated in function of the metal-to-ligand charge transfer and d-d transition intensities. The replacement of the divalent transition metal by a trivalent lanthanide leads to the formation of heteroleptic 4f-4f' dinuclear complexes of formula [Ln 2- x Ln' x (hfac) 6 (L)]· a (CH 2 Cl 2 )· b (C 6 H 14 ) and [Dy 1.11 Nd 0.89 (tta) 3 (hfac) 3 (L)]. The coordination selectivity is based on the radius. Among the 4f-4f' series, the Dy(III) derivatives displayed such ion in N 2 O 6 eight-coordinated sphere allowing the observation of SMM behavior. The three compounds [Dy 1.21 Nd 0.79 (hfac) 6 (L)]·2(CH 2 Cl 2 )·(C 6 H 14 ), [Yb 1.04 Nd 0.96 (hfac) 6 (L)] and [YbPr(hfac) 6 (L)] displayed respectively Nd(III), modarated Yb(III) and intense Yb(III) NIR emissions.

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. Therefore, we applied serial femtosecond crystallography at X-ray free electron lasers to in vivo-grown nanocrystals of these toxins. The structure of Cry11Aa was determined de novo using the single-wavelength anomalous dispersion method, which in turn enabled the determination of the Cry11Ba structure by molecular replacement. The two structures reveal a new pattern for in vivo crystallization of Cry toxins, whereby each of their three domains packs with a symmetrically identical domain, and a cleavable crystal packing motif is located within the protoxin rather than at the termini. The diversity of in vivo crystallization patterns suggests explanations for their varied levels of toxicity and rational approaches to improve these toxins for mosquito control., (© 2022. The Author(s).)

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. Those compounds emit both in solid state and in solution from the visible region to the NIR range, depending on the molecular structures. Quantum yields in cyclohexane reached unforeseen values for such derivatives, up to 7.8 %. A huge sensitivity to the environment of the TCBDs has also been unraveled for most of the compounds since we observed a dramatic fall of the quantum yields when changing the solvent from cyclohexane to toluene, while they are almost non-emissive in dichloromethane., (© 2022 Wiley-VCH GmbH.)

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 lum ) 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.e., the binaphtyl moiety) are modulated. The resulting {[Eu(hfac) 3 ((S)/(R)-L x )]} n (x = 1 and 3) and {[Eu(hfac) 3 ((S,S,S)/(R,R,R)-L x )]} n (x = 2 and 4) have been characterized by powder X-ray diffraction by comparison with the X-ray structures on single crystal of the Dy(III) analogs. In solution, the structure of the complexes is deeply modified and becomes monomeric. The nature of the ligand induces change in the shape of the CPL spectra in CH 2 Cl 2 solution. Furthermore, a large |g lum | = 0.12 of the magnetic-dipole transition for the [Eu(hfac) 3 ((S,S,S)/(R,R,R)-L 2 )] complex involving the ligand with three stereogenic elements and an extended 𝜋 system has been measured. This report also shows CPL measurements in solid state for the series of {[Eu(hfac) 3 ((S)/(R)-L x )]} n (x = 1 and 3) and {[Eu(hfac) 3 ((S,S,S)/(R,R,R)-L x )]} n (x = 2 and 4) polymers., (© 2021 Wiley Periodicals LLC.)

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 ( A 1 ) or with a fused coumarin derivative ( A 2 ), are incorporated in a triazacyclonane macrocyclic ligand L 1 or L 2 , respectively, for the design of Eu(III), Yb(III), and Gd(III) complexes. A combined photophysical/theoretical study reveals that A 1 presents a charge transfer character via through-space paracyclophane conjugation, whereas A 2 presents only local excited states centered on the coumarin-paracyclophane moiety, strongly favoring triplet state population via intersystem crossing. The resulting complexes Eu L 1 and Yb L 2 are fully emissive in red and near-infrared, respectively, whereas the Gd L 2 complex acts as a photosensitizer for the generation of singlet oxygen.

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) 3 ] 3- 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(H 2 O) 6 ) 3 [Eu(DPA) 3 ] 2 ·7H 2 O ( 1 ), {(Ca(H 2 O) 4 ) 3 [Eu(DPA) 3 ] 2 } n ·10 n H 2 O ( 2 ), and {Cu(DPA)(H 2 O) 2 } n ( 3 ), resulting from spontaneous crystallization in the presence of a divalent alkaline-earth cation and transmetalation, are reported. On the other hand, Tb-Xo4 is perfectly soluble in the crystallization media, stable in the presence of alkaline-earth dications, and slowly decomposes (within days) by transmetalation with transition metals. The original structure of [Tb 4 L 4 (H 2 O) 4 ]Cl 4 ·15H 2 O ( 4 ) is also described, where L represents a bis(pinacolato)triazacyclononane ligand. This paper also highlights a potential synergy of interactions between Tb-Xo4 and components of the crystallization mixtures, leading to the formation of complex adducts like {AdkA/Tb-Xo4/Mg 2+ /glycerol} in the protein binding sites. The observation of such multicomponent adducts illustrated the complexity and versatility of the supramolecular chemistry occurring at the surface of the proteins.

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. This study highlights the importance of a large conformational sampling to reconcile characteristic time in NMR with molecular dynamics simulations, where sampling in the microsecond range is needed. This study opens the door for a detailed mechanistic elucidation of the early steps of lanthanide complex-peptide or lanthanide complex-protein interaction or self-assembly processes.

A field-induced chiral Yb III 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 2 F 5/2 → 2 F 7/2 emission while the NIR-CPL is associated to the f-f transitions of the Yb III ion bearing chiral β-diketonate derived-camphorate ancillary ligands., (© 2021 Wiley-VCH GmbH.)

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. A significant improvement was observed in the case of the Eu 3+ complex, while the Yb 3+ analogue conserved photophysical properties in aqueous solvent. Two-photon (2P) microscopy imaging experiments on living T24 human cancer cells confirmed the spontaneous internalization of the probes and images with good signal-to-noise ratio were obtained in the classic NIR-to-visible configuration with the Eu 3+ luminescent bioprobe and in the NIR-to-NIR with the Yb 3+ one., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A textbook dysprosium dinuclear complex based on acetylacetone ligands, [Dy 2 (acac) 4 (μ 2 -acac) 2 (H 2 O) 2 ], 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., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The reaction between the 2,2'-benzene-1,4-diylbis(6-hydroxy-4,7-di- tert -butyl-1,3-benzodithiol-2-ylium-5-olate triad ( H 2 SQ ) and the metallo-precursor [Yb(hfac) 3 ]2H 2 O led to the formation of a dinuclear coordination complex of formula [Yb 2 (hfac) 6 ( H 2 SQ )]0.5CH 2 Cl 2 ( H 2 SQ-Yb ). After chemical oxidation of H 2 SQ in 2,2'-cyclohexa-2,5-diene-1,4-diylidenebis(4,7-di- tert -butyl-1,3-benzodithiole-5,6-dione ( Q ), the latter triad reacted with the [Yb(hfac) 3 ]2H 2 O precursor to give the dinuclear complex of formula [Yb 2 (hfac) 6 ( Q )] ( Q- Yb ). Both dinuclear compounds have been characterized by X-ray diffraction, DFT optimized structure and electronic absorption spectra. They behaved as field-induced Single-Molecule Magnets (SMMs) nevertheless the chemical oxidation of the semiquinone to quinone moieties accelerated by a factor of five the relaxation time of the magnetization of Q- Yb compared to the one for H 2 SQ-Yb . The H 2 SQ triad efficiently sensitized the Yb III luminescence while the chemical oxidation of H 2 SQ into Q induced strong modification of the absorption properties and thus a quenching of the Yb III luminescence for Q- Yb . In other words, both magnetic modulation and luminescence quenching are reached by the oxidation of the protonated semiquinone into quinone., Competing Interests: The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.

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.

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. These new crystalline forms bypass crystal defects often encountered by crystallographers, such as low-resolution diffracting samples or crystals with twinning. Thanks to Tb-Xo4's high phasing power, the structure determination process is greatly facilitated and can be extended to serial crystallography approaches.

Three new copper(I) complexes [Cu(L X ) 2 ] + (PF 6 - ) (where L X 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. Their electronic absorption and electrochemical properties are comparable to benchmark [Cu(dmp) 2 ] + (where dmp stands for 2,9-dimethyl-1,10-phenanthroline); furthermore, their optical features were fully reproduced by time-dependent density functional theory and ab initio molecular dynamics calculations. All three complexes are luminescent at room temperature, showing that halogen atoms bound to positions 2 and 9 of phenanthroline are sufficiently bulky to prevent strong interactions between the excited Cu complexes and solvent molecules in the coordination sphere. Their behavior in the excited state, more specifically the extent of the photoluminescence efficiency and its dependence on the temperature, is, however, strongly dependent on the nature of the halogen. A combination of ultrafast transient absorption spectroscopy, temperature-dependent steady-state fluorescence spectroscopy, and computational chemistry allows one to gain a deeper understanding of the behavior of all three complexes in their excited state.

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 2 fixation, sequesters its reactive intermediate acrylyl-CoA. Structural analysis showed that PCS forms a multicatalytic reaction chamber. Kinetic analysis suggested that access to the reaction chamber and catalysis are synchronized by interdomain communication. The reaction chamber of PCS features three active sites and has a volume of only 33 nm 3 . As one of the smallest multireaction chambers described in biology, PCS may inspire the engineering of a new class of dynamically regulated nanoreactors.

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 5 D 0 → 7 F 2 transition at 615 nm. Their brightness is excellent, in the range of the best lanthanide bioprobes making them very attractive for bio-imaging experiments., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Crystallophores are lanthanide complexes that act as powerful auxiliary for protein crystallography due to their strong nucleating and phasing effects. To get first insights on the mechanisms behind nucleation induced by Crystallophore, we systematically identified various elaborated networks of supramolecular interactions between Tb-Xo4 and subset of 6 protein structures determined by X-ray diffraction in complex with terbium-Crystallophore (Tb-Xo4). Such interaction mapping analyses demonstrate the versatile binding behavior of the Crystallophore and pave the way to a better understanding of its unique properties., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Many reactions within a cell are thermodynamically unfavorable. To efficiently run some of those endergonic reactions, nature evolved intermediate-channeling enzyme complexes, in which the products of the first endergonic reactions are immediately consumed by the second exergonic reactions. Based on this concept, we studied how archaea overcome the unfavorable first reaction of isoprenoid biosynthesis-the condensation of two molecules of acetyl-CoA to acetoacetyl-CoA catalyzed by acetoacetyl-CoA thiolases (thiolases). We natively isolated an enzyme complex comprising the thiolase and 3-hydroxy-3-methylglutaryl (HMG)-CoA synthase (HMGCS) from a fast-growing methanogenic archaeon, Methanothermococcus thermolithotrophicus HMGCS catalyzes the second reaction in the mevalonate pathway-the exergonic condensation of acetoacetyl-CoA and acetyl-CoA to HMG-CoA. The 380-kDa crystal structure revealed that both enzymes are held together by a third protein (DUF35) with so-far-unknown function. The active-site clefts of thiolase and HMGCS form a fused CoA-binding site, which allows for efficient coupling of the endergonic thiolase reaction with the exergonic HMGCS reaction. The tripartite complex is found in almost all archaeal genomes and in some bacterial ones. In addition, the DUF35 proteins are also important for polyhydroxyalkanoate (PHA) biosynthesis, most probably by functioning as a scaffold protein that connects thiolase with 3-ketoacyl-CoA reductase. This natural and highly conserved enzyme complex offers great potential to improve isoprenoid and PHA biosynthesis in biotechnologically relevant organisms., Competing Interests: The authors declare no conflict of interest.

Macromolecular crystallography suffers from two major issues: getting well-diffracting crystals and solving the phase problem inherent to large macromolecules. Here, we describe the first example of a lanthanide complex family named "crystallophore" (Xo4), which contributes to tackling both bottlenecks. This terbium complex, Tb-Xo4, is an appealing agent for biocrystallography, combining the exceptional phasing power of the Tb(iii) heavy atom with powerful nucleating properties, providing ready-to-use crystals for structure determination. Furthermore, protein/Tb-Xo4 co-crystals can be easily detected and discriminated from other crystalline by-products using luminescence. We demonstrate the potential of this additive for the crystallisation and structure determination of eight proteins, two of whose structures were unknown.

Fluorescent probes that are able to directly measure viscosity are attractive candidates for the study of intracellular environments. We report a new class of luminescent rotors, based on the sensitized emission of a terbium(III) complex. A 4-fold increase in both quantum yield and luminescence lifetime was observed in viscous media for the studied complexes, with a lifetime ranging from 0.23 to 0.89 ms over a broad range of viscosities (0.6-1200 cP). The presented approach, relying on the millisecond-scale luminescence lifetime of the lanthanide ions, was applied to fixed T24 cancer cells using temporal sampling lifetime imaging microscopy.

Luminescent core-shell crystals based on lanthanide tris-dipicolinate complexes were obtained from the successive growing of two different lanthanide complex layers. Selective or simultaneous emission of each part of the crystal can be achieved by a careful choice of the excitation wavelength., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Diffusion ordered NMR is implemented to determine accurately the mobility of paramagnetic tris-dipicolinate lanthanide complexes that are versatile probes of protein structure. It is shown that diffusion coefficient ratios can be measured with an accuracy of 1 % using a standard BPPLED pulse sequence, which allows for observing significant, though weak, variations when different species are interacting with the paramagnetic compound. We demonstrate that this approach is complementary to classical chemical shift titration experiments, and that it can be applied successfully to probe the supramolecular dynamic interactions between lanthanide complexes and small molecules on the one hand, or to determine rapidly their affinity for a targeted protein., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

We describe the synthesis and the physical properties of polyaromatic hydrocarbons (PAHs) containing a phosphorus atom at the edge. In particular, the impact of the successive addition of aromatic rings on the electronic properties was investigated by experimental (UV/Vis absorption, fluorescence, cyclic voltammetry) and theoretical studies (DFT). The physical properties recorded in solution and in the solid state showed that the P-containing PAHs exhibit properties expected for an emitter in white organic light-emitting diodes (WOLEDs)., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Palladium-catalyzed cross-coupling reactions between chlorinated 1,3,5-triazines (TZ) and tetrathiafulvalene (TTF) trimethyltin derivatives afford mono- and C3 symmetric tris(TTF)-triazines as donor-acceptor compounds in which the intramolecular charge transfer (ICT) is modulated by the substitution scheme on TTF and TZ and by chemical or electrochemical oxidation. The TTF-TZ-Cl2 and (SMe)2TTF-TZ-Cl2 derivatives show fully planar structures in the solid state as a consequence of the conjugation between the two units. Electrochemical and photophysical investigations, supported by theoretical calculations, clearly demonstrate that the lowest excited state can be ascribed to the intramolecular charge transfer (ICT) π(TTF)→π*(TZ) transition. The tris(TTF) compound [(SMe)2TTF]3-TZ shows fluorescence when excited in the ICT band, and the emission is quenched upon oxidation. The radical cations TTF(+•) are easily observed in all of the cases through chemical and electrochemical oxidation by steady-state absorption experiments. In the case of [(SMe)2TTF]3-TZ, a low energy band at 5000 cm(-1), corresponding to a coupling between TTF(+•) and TTF units, is observed. A crystalline radical cation salt with the TTF-TZ-Cl2 donor and PF6(-) anion, prepared by electrocrystallization, is described.

Induction of chirality in achiral aggregates of an oligo(p-phenylenevinylene) has been used to detect the enantiomeric excess in acids used in the resolution of chiral compounds. The chiral acids which induce helicity in the aggregates are present at only 10% of the concentration of the chromophore, whose chiroptical activity can be detected using circular dichroism spectroscopy. An ee of 10% in mixtures of (+) and (-) acids has been clearly evidenced in a series of samples using only 1.5 μg and concentration of approximately 10 μM of the chiral compound. The composition of both carboxylic and phosphoric acid derivatives can be detected, thanks to their binding to the dimerised core ureidotriazine unit attached at one end of the oligo(p-phenylenevinylene) which induces a preferred twist in the aggregated aromatic rod. This chiral arrangement is reflected in the Cotton effects that the assemblies show. The sign of the induced dichroic signal can be affected by the substituents around a stereogenic centre of otherwise identical configuration, and can lead to ambidextrous assemblies as seen in Cotton effects at different positions for different acids. While this technique can be used to detect enantiomeric excess, screening of the pure enantiomers is wise prior to the use of the method to detect scalemic mixtures. This supramolecular approach to evaluation of chiral content in samples could also be applied to other types of aggregates based on achiral molecules which show sensitivity to molecular chiral inducers.

The formation of helical self-assembled fibres by a C(3) symmetric molecule incorporating three tetrathiafulvalene units is shown to be influenced dramatically by the processing conditions, leading to a variety of different chiral forms, including unprecedented croissants., (This journal is © The Royal Society of Chemistry 2012)

The controlled preparation of chiral structures is a contemporary challenge for supramolecular science because of the interesting properties that can arise from the resulting materials, and here we show that a synthetic nonamphiphilic C(3) compound containing π-functional tetrathiafulvalene units can form this kind of object. We describe the synthesis, characterization, and self-assembly properties in solution and in the solid state of the enantiopure materials. Circular dichroism (CD) measurements show optical activity resulting from the presence of twisted stacks of preferential helicity and also reveal the critical importance of fiber nucleation in their formation. Molecular mechanics (MM) and molecular dynamics (MD) simulations combined with CD theoretical calculations demonstrate that the (S) enantiomer provides the (M) helix, which is more stable than the (P) helix for this enantiomer. This relationship is for the first time established in this family of C(3) symmetric compounds. In addition, we show that introduction of the "wrong" enantiomer in a stack decreases the helical reversal barrier in a nonlinear manner, which very probably accounts for the absence of a "majority rules" effect. Mesoscopic chiral fibers, which show inverted helicity, i.e. (P) for the (S) enantiomer and (M) for the (R) one, have been obtained upon reprecipitation from dioxane and analyzed by optical and electronic microscopy. The fibers obtained with the racemic mixture present, as a remarkable feature, opposite homochiral domains within the same fiber, separated by points of helical reversal. Their formation can be explained through an "oscillating" crystallization mechanism. Although C(3) symmetric disk-shaped molecules containing a central benzene core substituted in the 1,3,5 positions with 3,3'-diamido-2,2'-bipyridine based wedges have shown peculiar self-assembly properties for amphiphilic derivatives, the present result shows the benefits of reducing the nonfunctional part of the molecule, in our case with short chiral isopentyl chains. The research reported herein represents an important step toward the preparation of functional mesostructures with controlled helical architectures., (© 2011 American Chemical Society)

A series of bis(TTF) donors containing aromatic linkers between the two TTF units has been synthesized in order to investigate on the electronic structure of the oxidized species from an experimental and theoretical point of view. A mono(TTF)-pyridine compound has been also prepared and characterized by single-crystal X-ray diffraction analysis. Oxidation of a solution of 2,6-bis(TTF)-pyridine (TTF-Pyr-TTF) or of 1,3-bis(TTF)-benzene (TTF-Bz-TTF) in CH(2)Cl(2) with less than 0.1 equivalent of [Cp(2)Fe][PF(6)] gives rise to a seven-line EPR spectrum consistent with the hyperfine structure calculated by DFT for the corresponding radical monocation. Increasing the proportion of oxidant leads to a four-line hyperfine structure, similar to the quartet pattern observed after oxidation of mono(TTF)-pyridine (Pyr-TTF) or mono(TTF)-benzene (Bz-TTF). In good accordance with the very weak value of J calculated by DFT for the dicationic biradicals these four-line spectra are attributed to [2,6-bis(TTF)-pyridine](2+) and [1,3-bis(TTF)-benzene](2+). Similar experimental results are obtained for 1,4-bis(TTF)-benzene. In this case, however, electrochemical oxidation leads to the monoradical at low potential and to the diradical at higher potential, while only the diradical could be observed by electrochemical oxidation of 2,6-bis(TTF)-pyridine or of 1,3-bis(TTF)-benzene.

Four inner tetrathiafulvalene-sulfoxides have been synthesized upon reaction of tetrathiafulvalene (TTF), tetramethyl-tetrathiafulvalene (TMTTF), tetrakis (thiomethyl)-tetrathiafulvalene (TMT-TTF), and bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF) with enantiopure (+) or (-)-(8,8-dichlorocamphorylsulfonyl)-oxaziridine as oxidizing agent. Chiral HPLC studies indicate very weak enantioselectivities for TTF-SO 3 and TMTTF-SO 4, formation of racemic mixture in the case of TMT-TTF-SO 5, and a rather good selectivity, up to 44% ee, in the case of BEDT-TTF-SO 1. The solid state structures of TMTTF-SO 4 and TMT-TTF-SO 5 have been determined by single crystal X-ray diffraction. Both compounds crystallize as racemates in the centrosymmetric triclinic space group P-1. Theoretical calculations at DFT/B3LYP/6-31+G* level afford optimized geometries in good accordance with the experimental structures and emphasize the participation of the chiral sulfoxide group in HOMO and LUMO. Time-dependent DFT calculations corroborated with electronic circular dichroism spectra allow the assignment of the absolute configuration (R) for the major enantiomer of 1 when the (+)-sulfonyl-oxaziridine is used as oxygen transfer reagent. Preliminary semipreparative HPLC separation provided enantioenriched fractions up to 63% ee., (2009 Wiley-Liss, Inc.)

Chiral C(2)-symmetric electroactive bis(oxazolines) containing an EDT-TTF (ethylenedithio-tetrathiafulvalene) backbone, as promising multifunctional ligands and precursors for chiral molecular materials, were synthesized and structurally characterized, together with octahedral molybdenum and tungsten carbonyl complexes.

Reaction of 2,4,6-trichloro-1,3,5-triazine with lithiated tetrathiafulvalene (TTF) in stoichiometric conditions, followed by treatment with sodium methanolate, provides mono- and bis(TTF)-triazines as new covalently linked (multi)donor-acceptor systems. Single-crystal X-ray analyses reveal planar structures for both compounds, with formation of peculiar segregated donor and acceptor stacks for the mono(TTF)-triazine compound, while mixed TTF-triazine stacks establish in the case of the bis(TTF) derivative. Cyclic voltammetry measurements show reversible oxidation of the TTF units, at rather low potential, with no splitting of the oxidation waves in the case of the dimeric TTF, whereas irreversible reduction of the triazine core is observed. Intramolecular charge transfer is experimentally evidenced through solution electronic absorption spectroscopy. Time-dependent DFT calculations allow the assignment of the charge transfer band to singlet transitions from the HOMO of the donor(s) to the LUMO of the acceptor. Solution EPR measurements correlated with theoretical calculations were performed in order to characterize the oxidized species. In both cases the spectra show very stable radical species and contain a triplet of doublet pattern, in agreement with the coupling of the unpaired electron with the three TTF protons. The dication of the bis(TTF)-triazine is paramagnetic, but no spin-spin exchange interaction could be detected.