Photoluminescent materials based on PMMA and a highly-emissive octahedral molybdenum metal cluster complex

Materials that combine photoluminescence, optical transparency and facile processability are of high importance in many applications. This article reports on the development of photoluminescent poly(methyl methacrylate) materials based on novel highly emissive anionic molybdenum cluster complex [{Mo6I8}(OTs)6]2- (where OTs- is the p-toluenesulfonate ion). The materials were obtained by both solution and bulk copolymerisation of methyl methacrylate and (dMDAEMA)2[{Mo6I8}(OTs)6], where dMDAEMA+ is the polymerisable cation [2-(methacryloyloxy)ethyl]dimethyl-dodecylammonium. Evaluation of the resultant hybrid materials showed that one could combine the excellent photoluminescent properties of the cluster complex with the transparency and processability of PMMA

Characterization and cytotoxicity studies of thiol-modified polystyrene microbeads doped with [(Mo6X8)(NO3)6]2- (X=Cl, Br, I)

Halide octahedral molybdenum clusters [(Mo6X8)L6]n- possess luminescence properties that are highly promising for biological applications. These properties are rather dependent on the nature of both the inner ligands X (i.e. Cl, Br, or I) and the apical organic or inorganic ligands L. Herein, the luminescence properties and the toxicity of thiol-modified polystyrene microbeads (PS-SH) doped with [(Mo6X8)(NO3)6]2- (X=Cl, Br, I) were studied and evaluated using human epidermoid larynx carcinoma (Hep2) cell cultures. According to our data, the photoluminescence quantum yield of (Mo6I8)@PS-SH is significantly higher (0.04) than that of (Mo6Cl8)@PS-SH (6Br8)@PS-SH (6X8)@PS-SH showed that all three types of doped microbeads had no significant effect on the viability and proliferation of the cells

One-pot synthesis of {Mo6 I8 }4+ -doped polystyrene microspheres via a free radical dispersion copolymerisation reaction:{Mo6 I8 }4+ -doped polystyrene microspheres via free radical copolymerisation

Molybdenum octahedral clusters, when incorporated into an appropriate polymer matrix, are considered as promising agents for a range of biological applications. This work describes the one-pot synthesis, morphology and cellular toxicity of nano-sized polystyrene beads doped with luminescent cluster complexes [(Mo6X8)(NO3)6]2- (X=Cl, Br or I). Specifically, the particles were obtained by free radical dispersion copolymerisation of styrene and methacrylic acid or 4-vinylpyridine in the presence of the cluster complexes. The effects of the cluster loading in the reaction mixture on both the content of the final material and number-average molar mass of the copolymers were evaluated

Octahedral molybdenum cluster complexes with aromatic sulfonate ligands

This article describes the synthesis, structures and systematic study of the spectroscopic and redox properties of a series of octahedral molybdenum metal cluster complexes with aromatic sulfonate ligands (nBu4N)2[{Mo6X8}(OTs)6] and (nBu4N)2[{Mo6X8}(PhSO3)6] (where X- is Cl-, Br- or I-; OTs- is p-toluenesulfonate and PhSO3 - is benzenesulfonate). All the complexes demonstrated photoluminescence in the red region and an ability to generate singlet oxygen. Notably, the highest quantum yields (>0.6) and narrowest emission bands were found for complexes with a {Mo6I8}4+ cluster core. Moreover, cyclic voltammetric studies revealed that (nBu4N)2[{Mo6X8}(OTs)6] and (nBu4N)2[{Mo6X8}(PhSO3)6] confer enhanced stability towards electrochemical oxidation relative to corresponding starting complexes (nBu4N)2[{Mo6X8}X6]

Metal‐Cation Recognition in Water by a Tetrapyrazinoporphyrazine‐Based Tweezer Receptor

A series of zinc azaphthalocyanines with two azacrowns in a rigid tweezer arrangement were prepared and the fluorescence sensing properties were investigated. The size‐driven recognition of alkali and alkaline earth metal cations was significantly enhanced by the close cooperation of the two azacrown units, in which both donor nitrogen atoms need to be involved in analyte binding to switch the sensor on. The mono‐ or biphasic character of the binding isotherms, together with the binding stoichiometry and magnitude of association constants (KA), indicated specific complexation of particular analytes. Water solvation was shown to play an important role and resulted in a strong quenching of sensor fluorescence in the ON state. The lead compound was embedded into silica nanoparticles and advantageous sensing properties towards K+ were demonstrated in water (λF=671 nm, apparent KA=82 m−1, increase of 17×), even in the presence of (supra)physiological concentrations of Na+ and Ca2+.In a pinch: Close cooperation of azacrowns in fluorescence sensors derived from tetrapyrazinoporphyrazines is responsible for high sensitivity and selectivity towards particular cations. Water solvation, however, quenches the fluorescence strongly. Interestingly, embedding the sensor into silica nanoparticles overcomes this problem and result in an excellent red‐emitting fluorescence sensor (see figure).Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137532/1/chem201504268.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137532/2/chem201504268-sup-0001-misc_information.pd

Expanding luminescence horizons in macropolyhedral heteroboranes

Luminescence is observed in three novel macropolyhedral nineteen- and eighteen-vertex chalcogenaboranes: Se2B17H17 (1), SeB17H19 (3) and SeB18H20 (4). This led us to the recognition that previously published macropolyhedral heteroborane species might also exhibit luminescence. Thus, the known nineteen- and eighteen-vertex dithiaboranes S2B17H17 (2), n-S2B16H16 (5) and i-S2B16H16 (6) were synthesised and also found to exhibit a range of luminescent properties. These macropolyhedral species are very different from the previously unique fluorescent binary borane B18H22 in terms of their structural architectures, by the presence of borane cluster hetero atoms, and, as in the cases of 5 and 6, that their synthetic origins are not derived simply through the modification of B18H22 itself. They consequently greatly expand the possibilities of finding new luminescent inorganic borane species

Design and Integration in Electro-Optic Devices of Highly Efficient and Robust Red-NIR Phosphorescent Nematic Hybrid Liquid Crystals Containing [Mo6I8(OCOCnF2n+1)6]2− (n = 1, 2, 3) Nanoclusters

International audienceBy combining [Mo6I8(C n F2n+1COO)6]2- (n = 1, 2, 3) nanocluster units with liquid crystalline ammonium cations, a new series of hybrid materials is developed that show a nematic liquid crystal phase, the most fluid of all LC phase, on a large range of temperatures including room temperature. The photophysical studies performed in the LC state show that these self-assembled hybrid materials emit in the red-NIR with absolute quantum yields up to 0.7 and show a very good photostability under continuous irradiation. They are further integrated up to 20 wt% in E7, a well-known nematic commercial LC mixture. Mixtures are investigated in terms of homogeneity and stability to select the best suitable candidate for the design of electro-controlled devices. Studies of optical switching, contrast, viscosity, and behavior toward an electrical stimulus demonstrate the high potential of these hybrid materials in the fields of photonic or optoelectronic

Spin frustration in antiperovskite systems: (TTF˙+or TSF˙+)3[(Mo6X14)2−Y−]

Two novel antiperovskite charge-transfer (CT) solids composed of a tetraselenafulvalene radical cation (TSF˙+), a dianionic molybdenum cluster unit [Mo6X14]2−, and a halogen anion (Y−) (X, Y = Cl, Br) were prepared by electrocrystallization. Their crystal structures and magnetic properties with regard to spin frustration are discussed together with those of isostructural tetrathiafulvalene (TTF) CT solids previously reported. Both TSF and TTF salts have an apex sharing distorted octahedral spin lattice with a rhombohedral R[3 with combining macron] space group. The calculated overlap integrals based on the crystal structures and insulating nature of the TSF salts indicate that they are Mott insulators. Their spin susceptibilities obeyed the Curie–Weiss law and exhibited an antiferromagnetic ordering at lower temperatures for the TSF salts (Néel temperature, TN = 3.0 K for X = Y = Cl and 5.5 K for X = Y = Br) than the TTF salts. The Curie–Weiss temperatures (|ΘCW| ∼ 1.6–6.3 K) for the TSF salts are lower than those of the TTF salts. For the TSF salts, spin-flop behavior was detected at 3.2 T for X = Y = Cl and 1.5 T for X = Y = Br at 1.9 K. Due to both the distortion of the octahedral geometry of the spin lattice and the anisotropic molecular orientation, the geometrical spin frustrations in TSF and TTF systems are weakened