Stephane Petoud

French Institute of Health and Medical Research | Inserm · Center for Molecular Biophysics, CNRS UPR 4301, Orléans

Multiplex imaging in the second near‐infrared window (NIR‐II, 1000–1700 nm) provides exciting opportunities for more precise understanding of biological processes and more accurate diagnosis of diseases by enabling real‐time acquisition of images with improved contrast and spatial resolution in deeper tissues. Today, the number of imaging agents su...

Multiplex imaging in the second near‐infrared window (NIR‐II, 1000–1700 nm) provides exciting opportunities for more precise understanding of biological processes and more accurate diagnosis of diseases by enabling real‐time acquisition of images with improved contrast and spatial resolution in deeper tissues. Today, the number of imaging agents su...

We investigated the coordination properties of original macrocyclic Ln3+ complexes comprising an imidazothiadiazole heterocycle. The thermodynamic stability of the Gd3+ complex was determined by a combination of potentiometric and photophysical...

White light production is of major importance for ambient lighting and technological displays. White light can be obtained by several types of materials and their combinations, but single component emitters remain rare and desirable towards thinner devices that are, therefore, easier to control and that require fewer manufacturing steps. We have de...

Applying a single molecular probe to monitor enzymatic activities in multiple, complementary imaging modalities is highly desirable to ascertain detection and to avoid the complexity associated with the use of agents of different chemical entities. We demonstrate here the versatility of lanthanide (Ln³⁺) complexes with respect to their optical and...

Applying a single molecular probe to monitor enzymatic activities in multiple, complementary imaging modalities is highly desirable to ascertain detection and to avoid the complexity associated with the use of agents of different chemical entities. We demonstrate here the versatility of lanthanide (Ln3+) complexes with respect to their optical and...

The NASA Mars 2020 Perseverance rover is actively exploring Jezero crater to conduct analyses on igneous and sedimentary rock targets from outcrops located on the crater floor (Máaz and Séítah formations) and from the delta deposits, respectively. The rock samples collected during this mission will be recovered during the Mars Sample Return mission...

The syntheses of two macrocycles containing original imidazothiadiazole heterocycles are presented. The protonation constants of the ligands have been determined by potentiometry and photophysical measurements. The photophysical properties of the corresponding Tb³⁺ complexes have been analyzed and the sensitization of the Tb³⁺ by the heterocyclic m...

Near-infrared (NIR) luminescent lanthanide(III) (Ln ³⁺ ) metal organic frameworks (MOFs) constitute a class of materials possessing unique advantages for a wide range of applications due to their photophysical and structural properties....

By combining advantages of two series of lanthanide(III)/zinc(II) metallacrowns (MCs) assembled using pyrazine‐ (pyzHA²⁻) and quinoxaline‐ (quinoHA²⁻) hydroximate building blocks ligands, we created here water‐soluble mixed‐ligand MCs with extended absorption to the visible range. The YbIII analogue demonstrated improved photophysical properties in...

The effect of ligands' energy levels on thermal dependence of lanthanide emission was examined to create new molecular nanothermometers. A series of Ln2Ga8L8'L8″ metallacrowns (shorthand Ln2L8'), where Ln = Gd3+, Tb3+, or Sm3+ (H3L' = salicylhydroxamic acid (H3shi), 5-methylsalicylhydroxamic acid (H3mshi), 5-methoxysalicylhydroxamic acid (H3moshi),...

While complexity is observed everywhere in living organisms, it remains an outstanding challenge to establish controlled synthetic approaches allowing one to obtain a high level of programmed organization. Metal–organic frameworks (MOFs) belong to a fascinating family of materials with which it is possible to obtain different levels of structural c...

A set of (Ln[14-MCZn(II)N(quinHA)-5])2Ln2Zn2(quinHA)2(ph)2(Hph)4(OH)8(H2O)4 metallacrowns (Ln-1, Ln = Tb, Gd, or Yb; H2quinHA = quinaldic hydroxamic acid, H2ph = phthalic acid) have been synthesized via solution-state self-assembly. The metallacrowns possess an uncommon topology within the metallacrown family where two rarely seen 14-metallacrown-5...

The luminescence properties of two types of heterotrimetallic aluminum-lanthanide-sodium 12-metallacrown-4 compounds are presented here, LnNa(ben)4[12-MCAl(III)N(shi)-4] (LnAl4Na) and {LnNa[12-MCAl(III)N(shi)-4]}2(iph)4 (Ln2Al8Na2), where Ln = GdIII, TbIII, ErIII, and YbIII, MC is metallacrown, ben- is benzoate, shi3- is salicylhydroximate, and iph...

A family of Zn16Ln(HA)16 metallacrowns (MCs; Ln = Yb III , Er III , and Nd III ; HA = picoline-(picHA 2-), pyrazine-(pyzHA 2-), and quinaldine-(quinHA 2-) hydroximates) with an 'encapsulated sandwich' structure possesses outstanding luminescence properties in the near-infrared (NIR) and suitability for cell imaging. Here, to decipher which paramete...

Two series of stable aqueous colloidal solutions of Nd3+: LaF3 single-phase well-crystallized nanoparticles (NPs), possessing a fluorcerite structure with different activator concentrations in each series, were synthesized. A hydrothermal method involving microwave-assisted heating (HTMW) in two Berghof speedwave devices equipped with one magnetron...

Drug‐loaded liposomes are typical examples of nanomedicines. We show here that doxorubicin, the anti‐cancer agent in the liposomal drug Doxil, can sensitize Ytterbium (Yb³⁺) and generate its near‐infrared (NIR) emission. When doxorubicin and amphiphilic Yb³⁺ chelates are incorporated into liposomes, the sensitized emission of Yb³⁺ is dependent on t...

Drug‐loaded liposomes are typical examples of nanomedicine. We show here that doxorubicin, the anti‐cancer agent in the liposomal drug Doxil ® , can sensitize Ytterbium (Yb 3+ ) and generate its near infrared (NIR) emission. When doxorubicin and amphiphilic Yb 3+ chelates are incorporated into liposomes, the sensitized emission of Yb 3+ is dependen...

Pyridazino-1,3a,6a-triazapentalenes (PyTAP) are compact fused 6/5/5 tricyclic scaffolds which exhibit promising fluorescent properties. Chemically stable, they can be post-functionalized using standard Pd-catalyzed cross-coupling chemistry. Several original PyTAP bearing additional unsaturated substituents in positions 2 and 8 were synthetized and...

We report here a near-infrared (NIR) emitting lanthanide-based metal-organic framework (MOF) in which Yb3+ are sensitized by fluorescein (FL) as a low energy absorbing chromophore (FL@CD-MOF-161). The unique design of CD-MOF-161 allows for the entrapment of FL molecules in its pores during the synthesis and crystal growth, ensuring the efficient lo...

Lanthanide(III) ions (Ln3+) in coordination compounds exhibit unique luminescence properties with narrow and characteristic f-f transitions throughout the visible and near-infrared (NIR) ranges. In addition, some Ln3+ such as Pr3+, Sm3+, Dy3+, Ho3+, Er3+, and Tm3+ possess an exceptional ability, although less explored, to exhibit dual-range emissio...

Herein, the synthesis and characterization of the first family of multipodal ligands with a Tröger's base framework designed for the preparation of luminescent lanthanide(III) complexes are reported. Eight ligands were designed and synthesized using different strategies, including alkylation reactions, amide couplings, and Ugi multicomponent reacti...

Nanothermometry is the study of temperature at the submicron scale with a broad range of potential applications, such as cellular studies or electronics. Molecular luminescent‐based nanothermometers offer a non‐contact means to record these temperatures with high spatial resolution and thermal sensitivity. A luminescent‐based molecular thermometer...

The interest in ratiometric luminescent probes that detect and quantify a specific analyte is growing. Owing to their special luminescence properties, lanthanide(III) cations offer attractive opportunities for the design of dual‐color ratiometric probes. Here, the design principle of hetero‐bis‐lanthanide peptide conjugates by using native chemical...

Single lanthanide(III) ion white light emission is in high demand since it provides the advantage of requiring only one chromophore for the control of the color. Herein, a series of Ga3+/Dy3+ metallacrowns (MCs) is presented, demonstrating outstanding white light colorimetric properties with CIE chromaticity coordinates of (0.309, 0.334) and correl...

Herein, the design, synthesis, and characterization of a phenhomazine ligand are described. The ligand has six pendant acetate arms designed for the combined coordination of copper(II) and lanthanide(III) ions, with the perspective of developing a “turn‐off” copper sensor. The key step for the ligand preparation was the one‐step endomethylene bridg...

Galactofuranose is a rare form of the well-known galactose sugar, and its occurrence in numerous pathogenic micro-organisms makes the enzymes responsible for its biosynthesis interesting targets. Herein, we review the role of these carbohydrate-related proteins with a special emphasis on the galactofuranosidases we recently characterized as an effi...

A strategy based on the use of ligand steric hindrance and metal doping is reported for the design and synthesis of near-infrared (NIR) emitting lanthanide-based metal-organic frameworks (MOFs). The lanthanide...

While metal-organic frameworks (MOFs) have been identified as promising materials for sensitizing near-infrared emitting lanthanide ions (Ln3+) for biological imaging, long-wavelength excitation of such materials requires large, highly delocalized organic linkers or guest-chromophores. Incorporation of such species generally coincides with fewer Ln...

A new series of gallium(III)/lanthanide(III) metallacrown (MC) complexes (Ln-1) was synthesized by the direct reaction of salicylhydroxamic acid (H3shi) with GaIII and LnIII nitrates in a CH3OH/pyridine mixture. X-ray single crystal analysis revealed two types of structures depending on whether the nitrate counterion coordinate or not to the LnIII:...

Multimodal probes capable of combining imaging modalities within a single molecule are in high demand today as they can provide information at both molecular and anatomical levels. Herein, a study was conducted on a series of gallium(III)/lanthanide(III) bis(12‐MC‐4) metallacrowns (MCs) with the general composition {Ln[12‐MCGaIIIN(shi)‐4]}2(iph)4 (...

Herein, we report the synthesis and characterization of heterobimetallic Zn‐4f complexes formed by the “valnap” ligand (L¹) with extended aromaticity, thereby acting as visibly absorbing antenna for generating the near‐infrared (NIR) luminescence of three different lanthanide(III) ions (Ln³⁺). The series of new Zn(py)L¹Ln(NO3)3 complexes [Ln = Yb (...

In this contribution we build up on our previous work on the MOF [Mg(H2dhtp)(H2O)2]∙DMAc (AEMOF-1∙DMAc) and its activated dry version AEMOF-1′ which has been shown to exhibit excellent luminescence sensing properties towards water in organic solvents. We demonstrate through combined structural and photophysical studies that the observed changes in...

An unusual class, compact in sizes, of fluorescent probes based on pyridazino-1,3a,6a-triazapentalene scaffolds exhibits highly fluorescent properties (quantum yield values up to 73%, large Stokes shifts, emission wavelengths located in...

Thanks to their versatile magnetic and luminescence features, lanthanide complexes have gained a central position in biomedical imaging as magnetic resonance imaging (MRI) contrast agents and optical imaging probes. In addition, appropriate chemical design allows modification of the magnetic relaxation properties of GdIII complexes and the optical...

Despite the crucial role of the rare galactofuranose (Galf) in many pathogenic micro-organisms and our increased knowledge of its metabolism, there is still a lack of recombinant and efficient galactofuranoside hydrolase available for chemo-enzymatic synthetic purposes of specific galactofuranosyl-conjugates. Subcloning of the Galf-ase from JHA 19...

The unique luminescence properties of lanthanide(III) ions (Ln3+) in the near-infrared (NIR) range are attracting major attention in view of their exciting applications in the fields of technology, telecommunications, biology, and medicine. One of the main strategies to design luminescent Ln3+-based compounds relies on their sensitization through a...

NIR Ln( iii ) complexes combining a cyclen derivative, azo-dye as a sensitizer and a cRGD peptide as a targeting moiety.

We successfully demonstrate that metal-organic frameworks (MOFs) can be designed to be excited and emit within the biological diagnostic window (650–1450 nm). An isoreticular series of anionic rare earth MOFs with fcu topology was synthesized using 10 different rare earth elements (Y3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+) and comm...

Molecular erbium complexes are on the dark side of luminescence, with usually no emitted visible light. Upon systematic tuning of the peripheral ligands, a rare metal‐centered green fluorescence can be implemented, which paves the way for lanthanide‐based molecular upconversion. More information can be found in the Full Paper by S. Petoud, A. Hause...

We have designed a rigid photocleavable dianthracene-based ligand that reacts with ytterbium as coordination metal ion for the creation of a class of tridimensional light-degradable metal–organic framework (MOF). We demonstrated that we can obtain a high level of control on the disassembly of the MOF formed with this ligand which can be triggered e...

Intrigued by the unexpected room‐temperature dual visible‐NIR luminescence observed for fast‐relaxing erbium complexes embedded in triple‐stranded helicates, this contribution explores a series of six tridentate N‐donor receptors L4‐L9 with variable aromaticities and alkyl substituents for extricating the stereo‐electronic requirements responsible...

The present invention relates to a complex comprising at least one dendrimer and at least one lanthanide, in which the dendrimer comprises a unit of formula (I), wherein: C1 is a group with a valency of 4 of formula >N-CH2-CH2-N<; and - A1, A2 and A3 are groups of formula -(CH2)2-C(O)-NH-(CH2)2-; said unit of formula (I) being covalently bound to a...

We report here two isoreticular ytterbium (Yb) 2D metal-organic frameworks (MOFs) emitting near-infrared (NIR) luminescence with 1.26(2)% quantum yield values, which are among the highest values reported to date for MOFs incorporating NIR-emitting lanthanide cations. The excitation wavelength of the YbIII MOFs can be red-shifted to the visible rang...

A new family of [3.3.1] metallacryptates with the general composition [LnGa6(H2shi)(Hshi)(shi)7(C5H5N)] (Ln‐1; shi3‐ = salicylhydroximate; Ln = Pr, Nd, Sm ‐ Yb) has been synthesized and characterized. Ln‐1 display both interesting magnetic and luminescent properties. Sm‐1 has sharp emission bands in the visible and the near‐infrared (NIR) regions w...

Self-aggregating calix[4]arenes carrying four DOTA ligands on the upper rim for stable complexation of paramagnetic GdIII-ions have already been proposed as MRI probes. In this work, we investigate the luminescence properties of TbIII-DOTA-calix[4]arene-4OPr containing four propyl-groups and compare them with those of the analog substituted with a...

New functional coordination polymers based on the semi-flexible 9,10-di(1H-imidazol-1-yl)-anthracene ligand (L) with ZnII and CdII, namely {[Zn(μ2-L)2](ClO4)2·m(MeOH)·n(DCM)}n (1), {[Zn(μ2-L)2](BF4)2·m(MeOH)·n(DCM)}n (2), {[Zn(μ2-L)2(p-Tos)2]·mDCM·nMeOH}n (3), {[Cd(μ2-L)2(p-Tos)2]·mDCM}n (4) {[Cd(μ2-L)2(p-Tos)2]·mMeOH·nDioxane}n (5) and {[Zn(μ2-L)2...

GaIII/LnIII metallacrown (MC) complexes with a dimeric structure have been designed, synthesized and characterized. The presence of the bridge in the [LnGa4]2 allows for a broad variety of functionalization with chemical groups of different nature through carboxylate substitution. Moreover, the MC scaffold in [LnGa4]2 is able to efficiently sensiti...

The Front Cover shows, at the center, the structure of a DOTA-based ligand with a tropone coordinating sidearm. The ligand forms monohydrated lanthanide chelates. The GdIII complex is a good T1-shortening MRI agent, as illustrated in the blue field by the MR images of the kidneys and the liver of a mouse. The tropone unit is an efficient sensitizer...

Invited for the cover of this issue are the groups of Zoltan Kovacs from the University of Texas Southwestern Medical Center, USA, and Svetlana Eliseeva from Centre de Biophysique Moléculaire, Orléans, France. The cover image shows the structure of a DOTA-based ligand, whose lanthanide complexes are useful imaging probes.

Metal-containing (bio)organic polymers are materials of continuously increasing importance for applications in energy storage and conversion, drug delivery, shape-memory items, supported catalysts, organic conductors and smart photonic devices. The embodiment of luminescent components provides a revolution in lighting and signaling with the ever-in...

A family of dimeric LnIII[12-MCGa(III)N(shi)-4] metallacrowns (MCs) (LnIII = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, and Yb) was synthesized using the isophthalate group (ip2-) as a linker. The [LnGa4]2 complexes exhibit remarkable photophysical properties, with large molar absorptivities of ~ 4×104 M-1 cm-1, high quantum yields and long luminescen...

Cell fixation is an essential approach for preserving cell morphology, allowing the targeting and labelling of biomolecules with fluorescent probes. One of the key requirements for more efficient fluorescent labelling is the preservation of cell morphology, which usually requires a combination of several fixation techniques. In addition, the use of...

In this work, we describe a novel DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) based ligand with a chromophoric tropone coordinating sidearm (1). Ln3+ complexes of 1 have one inner sphere water molecule. The r1 relaxivity of Gd1 is similar to that of the commercial Gd-based MRI agents. The neutral O-donor atom of the tropone moie...

Responsive luminescent probes emitting in the near-infrared (NIR) are in high demand today for biological applications as they allow for the easy and unambiguous discrimination of autofluorescence. Due to their luminescence properties, lanthanide ions offer an interesting alternative to classical organic fluorescent dyes. This has stimulated the de...

The Td point group symmetry of rare earth (RE3+) metal clusters RE4(μ3-OH)4(COO)62+ makes them attractive building blocks for creating metal-organic frameworks (MOFs) with controllable topologies. Herein, we describe the design and synthesis of a series of isoreticular MOFs featuring pcu topology [MOF-1114(RE) and MOF-1115(RE)] with variable rare e...

Sensitive detection of cell necrosis is crucial for the determination of cell viability. Because of its high resolution at the cellular level and sensitivity, optical imaging is highly attractive for identifying cell necrosis. However, challenges associated with this technique remain present such as the rapid photobleaching of several types of orga...

Beta-(1 → 3)-glucans constitute highly promising biomolecules as evidenced by their immunostimulating ability which were first used as folk medicine in Chinese populations and further identified in fungi, yeasts and seaweeds. Previous investigations showed that glucans proteins interaction mediate cell growth pathways. We have adopted this approach...

In this Article, we report the self-assembly of lanthanide complexes formed with two new tripodal ligands, L2 and L3, where binding strands are connected to a rigid triptycene anchor. The pyridine moieties are functionalized with methoxy and PEG groups to enhance ligand solubility and to evaluate the effect of these substituents on lanthanide coord...

Recently, a strong interest has been directed towards near-infrared (NIR) emitting lanthanide(III) compounds as they do possess complementary advantages in respect to organic molecules and semi-conductor nanocrystals, especially in the fields of biological analysis and imaging. To benefit from their emission, a key requirement to fulfill is the sen...

As for any thermotropic liquid crystals (often referred to as mesogens), those containing transition metals (metallomesogens), and more specifically lanthanides (lanthanidomesogens) would benefit from rational correlations between the microscopic variations introduced by chemists in their molecular structures and some planned macroscopic properties...

Fluorescence optical imaging is a highly sensitive and powerful tool with diverse in vitro and in vivo applications for preclinical and clinical studies. This review is focused on the optical imaging in the near-infrared (NIR) region since improved signal-to-noise ratio and deeper penetration of light through tissues could be achieved due to the mi...

Considered at the beginning of the 21th century as being incompatible with the presence of closely bound high-energy oscillators, lanthanide-centered superexcitation, which is the raising of an already excited electron to an even higher level by excited-state energy absorption, is therefore a very active topic strictly limited to the statistical do...

Full and congruent crystallization from glass is applied to the SrREGa3O7 melilite family (RE = Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Y). This innovative process enables the synthesis of polycrystalline ceramics exhibiting high transparency both in the visible and near infra-red regions, despite tetragonal crystal structures and micrometer scale grain...

We report first prototypes of responsive lanthanide(III) complexes that can be monitored independently in three complementary imaging modalities. Through the appropriate choice of lanthanide(III) cations, the same reactive ligand can be used to form complexes providing detection by (i) visible (Tb(3+)) and near-infrared (Yb(3+)) luminescence, (ii)...

Hypoxia-inducing pathologies as cancer develop pathologic and inefficient angiogenesis which rules tumor facilitating microenvironment, a key target for therapy. As such, the putative ability of endothelial precursor cells (EPCs) to specifically home to hypoxic sites of neovascularization prompted to design optimized, site-specific, cell-mediated,...

Most of the existing optical methods for CuII detection rely on a "turn-off" approach using visible lanthanide(III) luminescence. In this work we present an innovative molecular systems where the podands bis(2-hydrazinocarbonylphenyl) ethers of ethylene glycol (L1) and diethylene glycol (L2) have been designed, synthesised and tested with an ultima...

The development of efficient sensors for the determination of the water content in organic solvents is highly desirable for a number of chemical industries. Presented herein is a Mg2+ metal–organic framework (MOF), which exhibits the remarkable capability to rapidly detect traces of water (0.05–5 % v/v) in various organic solvents through an unusua...