Much research has been devoted to molybdenum octahedral clusters Mo 6 since the discovery of the A x Mo 6 Y 8 solidstate series (Y = S, Se, Te) in the early 1970s.[1] Indeed, their interesting physical properties and potential applicationse.g., superconductivity at high critical field, thermoelectric, catalysis, or redox intercalation processes -have stimulated the research of many groups. [2] (Fig. 1). The physical properties of Mo 6 solid-state compounds are related to the number of electrons available for metal-metal bonding within the cluster (valence electron count, VEC) and to the strength of interaction between the units. Mo-centered electrons are located on twelve metal-metal bonding molecular orbitals of the molecular orbital diagram. Their full occupation leads to a closed-shell configuration with a VEC of 24.[ [8,9] that can be used for the formation and organization of supramolecular assemblies as well as hybrid materials. Hybrids can be synthesized either by the grafting of functional donor ligands in apical position or through the association of anionic cluster units with organic or organometallic cations by cation metathesis or electrochemical techniques.[10]The large emission region of the [Mo 6 X 14 ] 2-anion in the red and near infrared (580-900 nm) is particularly interesting for biotechnology applications as it is selectively transmitted through tissues owing to the relatively low absorption at these wavelengths.[11] Anionic Mo 6 cluster units are usually associated with alkali counter cations within inorganic solids. Indeed, the use of inorganic cluster compounds as luminescent dyes, for instance in bio-imaging strategies, presupposes that both clusters and counter cations are embedded in an inert matrix in order to avoid ionic diffusion, oxidization of the cluster, or apical ligand exchanges in aqueous media, which will precipitate the cluster as a hydroxo species.

Octahedral metal atom clusters in which metallic atoms are held together by metal-metal bonds are commonly found in solid-state compounds prepared by high-temperature synthesis.[1] The metallic octahedron is surrounded by eight facecapping and six terminal ligands to form a [M 6 units (X = halogen) that exhibit, either in the liquid or solid state, specific electronic, magnetic, and photophysical properties related to the number of metallic electrons available for metal-metal bonds. [3] In particular, they are highly emissive in the red-NIR region, have photoluminescence quantum yields of up to 0.23, [3d] display long excited-state lifetimes, [3d, 4] and undergo facile ground-and excited-state electron transfer by electrogenerated luminescence.[5] Owing to the stronger covalent nature of the M À Q i bond relative to the M À X a one, halogen apical atoms can be replaced by inorganic or organic ligands without any alteration of the (M 6 Q i 8 ) m+ core, leading to functional building blocks usable for the design of supramolecular architectures, polymeric frameworks, or nanomaterials with unique properties.[6] Although many examples of hexasubstituted [M 6 xÀ units (L = organic ligand) have been reported, [6d, 7] their integration in macroscopic devices by a bottom-up approach remains a challenge. This task requires systems with self-organization abilities on the one hand and fluidity on the other hand, to correct automatically the positioning errors that can occur during the assembly process. Metal-containing liquid crystals (metallomesogens) are the typical examples in which the unique properties of anisotropic fluids are combined with the specific properties of metals (e.g. geometry of coordination, optic, electronic, magnetic).[8] However, mesomorphic materials containing covalent metal-metal-bonded entities are rare, and all examples described up to now, since the pioneer work of Marchon and co-workers, [9] are based on dinuclear metalmetal-bonded species.[10] The association of mesomorphism with the peculiar properties of metallic clusters should lead to clustomesogens that offer great potential in the design of new electricity-to-light energy conversion systems, optically based sensors, and displays.In the scope of our work dedicated to transition-metalcluster based multifunctional materials, [11] we report herein the elaboration and characterization of liquid-crystalline materials based on a Mo 6 cluster. The synthesis is straightforward and consists of the one-step reaction of [Mo 6 Br 8 F 6 ] 2À units with carboxylic acid derivatives (Scheme 1), which results in the in situ exchange of apical F À by carboxylate anion along with the formation of HF.Owing to the bulkiness of the cluster unit and to its octahedral coordination, [12] we used a strategy based on the

The embedding of functional inorganic entities into polymer matrices has become an intense field of investigation in which the main challenges are to keep the added value of the inorganic entities while preventing their self-aggregation within the organic matrix. We present a simple way to obtain a homogeneous highly red-NIR luminescent hybrid copolymer that contains covalently bonded nanometric-sized {Re(6)} octahedral clusters. The [Re(6)Se(i)(8)(OH)(a)(6)](4-) cluster complexes are primarily functionalized in two steps with tert-butylpyridine (TBP) and methacrylic acid (MAC) to give neutral [Re(6)Se(8)(TBP)(4)(MAC)(2)] building blocks that are copolymerized with methyl methacrylate (MMA) either in solution or in bulk in the presence of azobisisobutyronitrile as an initiator. Several samples containing 0, 0.025, 0.05, and 0.1 wt % of functionalized {Re(6)} clusters were prepared. As the {Re(6)} cluster/MMA ratio is very low, the obtained copolymers keep the entire processability of pure poly(methyl methacrylate) (PMMA), as demonstrated by differential scanning calorimetry and thermogravimetric analysis. Voltammetric and luminescence studies also indicate that the intrinsic properties of the clusters are preserved within the polymer matrix. All the samples show a bright (emission quantum yield=0.07), broad, and structureless emission band, which extends from lambda=600 nm to more than lambda=950 nm, with the maximum wavelength centered around lambda(em)=710 nm either in solution or in the solid state. Moreover, the high stability of the incorporated inorganic phosphors prevents the material from photobleaching, and thus the luminescence properties are kept entirely even after nine months of ageing.

ZnO is a wide bandgap (3.37 eV) semiconductor with a large exciton binding energy. [1] In the bulk or in nanometer-sized form, it could be used in a wide range of applications, such as UV light emitters, spin functional devices, gas sensors, transparent electronics, or surface acoustic wave devices. [1][2][3] Various chemical, electrochemical, or physical deposition methods have been used to prepare functional ZnO materials. [1][2][3] Here, the strategy presented to design new hybrid materials is based on the chemical synthesis of ZnO organosols. Even though this ''bottom-up'' approach has been known for more than 20 years, [3][4][5][6] the preparation of innovative functional organosol ZnO materials (denoted as M@ZnO) by doping or functionalizing constitutes a recent challenge. [3,[7][8][9][10][11][12][13] For instance, (Mn, Co or Ni)@ZnO diluted magnetic semiconductor quantum dots (DMS-QDs) were used to prepare high-TC ferromagnetic nanocrystalline thin films, [7,8] and highly concentrated Er@ZnO or Ti@ZnO organosols were used to fabricate planar near-IR (NIR) amplifiers, [9] and new visiblelight photocatalytic nanocoatings, [10,11] respectively. Moreover, the recently developed hybrid materials based on ZnO/ metal or ZnO/SWCNT (SWCNT ¼ single walled carbon nanotube) nanojunctions might become of particular interest for photo-electrochemical applications. [12,13] cluster units and the ZnO nanocrystals were evidenced by phosphorescence decay measurements both in colloidal and solid-state forms. Interestingly, the visible photoemission window of the ((n-C 4 H 9 ) 4 N) 2 Mo 6 Br 14 @ZnO hybrid material is very large and can be tuned from yellow to red by adjusting the excitation wavelength. For an excitation wavelength of 395 nm, the emission window ranges from 430 to 850 nm. This hybrid material represents a promising candidate for use as a

The reaction of [Re6Q(i)8(OH)(a)6]4- (Q = S, Se) with p-tert-butylpyridine (TBP) in water leads to neutral trans-[Re6Q8(TBP)4(OH)2] whose hydroxyl reactivity with carboxylic acid and TBP exchange reaction with functional pyridine have been investigated.

Nanostructured silica coated bifunctional nanoparticles based on [Mo(6)Br(14)](2-) units as phosphorescent dye and magnetic gamma-Fe(2)O(3) nanocrystals were synthesized and characterized.

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Octahedral metal atom clusters in which metallic atoms are held together by metal-metal bonds are commonly found in solid-state compounds prepared by high-temperature synthesis. [1] The metallic octahedron is surrounded by eight facecapping and six terminal ligands to form a [M 6 Q i 8 Q a 6 ] 2À nanosized unit (Q = chalcogen/halogen, i = inner, a = apical). Many routes [2] afford soluble discrete [M 6 Q i 8 X a 6 ] 2À units (X = halogen) that exhibit, either in the liquid or solid state, specific electronic, magnetic, and photophysical properties related to the number of metallic electrons available for metal-metal bonds. [3] In particular, they are highly emissive in the red-NIR region, have photoluminescence quantum yields of up to 0.23, [3d] display long excited-state lifetimes, [3d, 4] and undergo facile ground-and excited-state electron transfer by electrogenerated luminescence. [5] Owing to the stronger covalent nature of the M À Q i bond relative to the M À X a one, halogen apical atoms can be replaced by inorganic or organic ligands without any alteration of the (M 6 Q i 8 ) m+ core, leading to functional building blocks usable for the design of supramolecular architectures, polymeric frameworks, or nanomaterials with unique properties. [6] Although many examples of hexasubstituted [M 6 Q i 8 L a 6 ] xÀ units (L = organic ligand) have been reported, [6d, 7] their integration in macroscopic devices by a bottom-up approach remains a challenge. This task requires systems with self-organization abilities on the one hand and fluidity on the other hand, to correct automatically the positioning errors that can occur during the assembly process. Metal-containing liquid crystals (metallomesogens) are the typical examples in which the unique properties of anisotropic fluids are combined with the specific properties of metals (e.g. geometry of coordination, optic, electronic, magnetic). [8] However, mesomorphic materials containing covalent metal-metal-bonded entities are rare, and all examples described up to now, since the pioneer work of Marchon and co-workers, [9] are based on dinuclear metalmetal-bonded species. [10] The association of mesomorphism with the peculiar properties of metallic clusters should lead to clustomesogens that offer great potential in the design of new electricity-to-light energy conversion systems, optically based sensors, and displays.In the scope of our work dedicated to transition-metalcluster based multifunctional materials, [11] we report herein the elaboration and characterization of liquid-crystalline materials based on a Mo 6 cluster. The synthesis is straightforward and consists of the one-step reaction of [Mo 6 Br 8 F 6 ] 2À units with carboxylic acid derivatives (Scheme 1), which results in the in situ exchange of apical F À by carboxylate anion along with the formation of HF.Owing to the bulkiness of the cluster unit and to its octahedral coordination, [12] we used a strategy based on the Scheme 1. Schematic representation of (nBu 4 N) 2 [Mo 6 Br 8 F 6 ] and the galli...