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 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.

Octahedral anionic rhenium clusters are obtained by hightemperature solid-state chemistry synthesis as single crystals or powders within which their charge is counter balanced by alkali cations. The ceramic-like behavior of the solid-state Re 6 based inorganic compound limits strongly their use in functional devices. We present herein a facile route to introduce these anionic clusters in a self-organized hybrid organic−inorganic material. By replacing alkali countercations by mesogenic organic ones, polarized optical microscopy (POM), DSC, Xray, magnetic, fluorescence, and cyclic voltammetry techniques confirm that a lyotropic and thermotropic liquid crystal material, able to switch reversibly from a bright red NIR luminescent form to a magnetic green-colored one, is obtained.

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...

This work presents the synthesis and studies of a red-NIR luminescent liquid crystal compound based on an octahedral metallic cluster core orthogonally bounded to six non-mesogenic organic ligands. It evidences synergetic effects between the organic and inorganic parts of the hybrid, resulting in the generation of liquid crystal properties on cooling from the isotropic melt.