Homoleptic frameworks of the formula 3 N [Sr 1Àx Eu x (Im) 2 ] (1) (x = 0.01-1.0; Im À = imidazolate anion, C 3 H 3 N 2 À ) are hybrid materials that exhibit an intensive green luminescence. Tuning of both emission wavelength and quantum yield is achieved by europium/strontium substitution so that a QE of 80% is reached at a Eu content of 5%. Even 100% pure europium imidazolate still shows 60% absolute quantum efficiency. Substitution of Sr/Eu shows that doping with metal cations can also be utilized for coordination compounds to optimize materials properties. The emission is finely tuneable in the region 495-508 nm via variation of the europium content. The series of frameworks 3 N [Sr 1Àx Eu x (Im) 2 ] presents dense MOFs with the highest quantum yields reported for MOFs so far.Framework and MOF chemistry 1 have attracted attention, as interesting properties were reported like conductivity, 2 catalytic effects, 3 luminescence 4 and porosity. 5 They are mainly known for oxygen coordinating ligands, mostly metal carboxylates 6 which include the alkaline earth and 4f elements. 7 Because of the oxophilicity of lanthanides oxygen-free multi-dimensional coordination networks are rarely found except for a few rare earth imidazolates and triazolates. 8 Among transition metals the imidazole ring system is of exceptional interest together with several 3d metals as they adopt zeolite structures (ZIFs) 9 that can be used for sorption and gas separation. Different from many solid state phosphors, coordination compounds can exhibit luminescence by metal ions although they contain 100% luminescence centres. 10 An expected quenching by concentration is suppressed by ligand shielding. They are furthermore interesting luminescent hybrid materials, as emission can be achieved either via a fluorescence of the ligand system 11 or the metal centres, mainly by the use of lanthanides. 4 The excitation can benefit from antenna effects, viz. the ligand system is excited primarily followed by a transfer of the energy to the luminescence centres. 12 However there are only little coordination compounds for which effective emission characterized by high quantum efficiencies has been reported. 4,11,13 Mostly, no quantum yields were determined, although luminescence becomes important for MOFs concerning sensoring and lighting from UV to near IR. 14,15 We now report a series of homoleptic imidazolate frameworks containing divalent strontium and europium that shows an exceptional combination of properties: an effective luminescence with the highest quantum yield reported for coordination polymers today, together with multiple excitation options including excitation maxima at the applicationally important wavelengths 370 and 460 nm (for Hg and blue LED excitation). The emission can be finely tuned in the region 495-508 nm (blue-green to green) via variation of the Eu content (Fig. 1). Furthermore a low quenching by concentration is observed, combined to a high thermal stability of the frameworks up to 530 1C. (1) are obtained by reactions of t...

A new polymorph of phosphorus nitride imide HP4N7 has been synthesized under high-pressure/high-temperature conditions from P3N5 and NH4Cl at 6 GPa and temperatures between 800 and 1300 °C. Its crystal structure was elucidated using single-crystal X-ray diffraction data. β-HP4N7 (space group C2/c, no. 15, Z = 4, a = 12.873(2) Å, b = 4.6587(4) Å, c = 8.3222(8) Å, β = 102.351(3)°, R1 = 0.0485, wR2 = 0.1083) crystallizes in a new framework structure type that is made up of all-side vertex-sharing PN4 tetrahedra. The topology of the network is represented by the point symbol (3(2).4(2).5(2).6(3).7)(3(4).4(4).5(4).6(3)), and it has not been identified in other compounds so far. Structural differences between the two polymorphs of HP4N7 as well as the topological relationship to the recently discovered high-pressure polymorph β-HPN2 are discussed. Additionally, FTIR and solid-state NMR spectroscopy are used to corroborate the results of the structure determination.

A hitherto unknown synthetic access to alkali lithosilicates, a substance class first described by Hoppe in the 1980s, is reported. With the synthesis and characterization of NaK7[Li3SiO4]8, a new representative has been discovered, expanding the family of known alkali lithosilicates. Astonishingly, NaK7[Li3SiO4]8 and the already established alkali lithosilicates Na[Li3SiO4] as well as K[Li3SiO4] display unforeseen luminescence properties, when doped with Eu2+. Na[Li3SiO4]:Eu2+ exhibits an ultra‐narrow blue, K[Li3SiO4]:Eu2+ a broadband, and NaK7[Li3SiO4]8:Eu2+ a yellow‐green double emission upon excitation with near‐UV to blue light. Consequently, all of the investigated substances of this class of compounds are highly interesting phosphors for application in phosphor converted LEDs.

The new narrow-band red-emitting phosphor material Sr 4 [LiAl 11 N 14 ]:Eu 2+ was synthesized by solid-state reaction using a tungsten crucible with a cover plate in a tube furnace. When excited with blue light (460 nm), it exhibits red fluorescence with an emission maximum at 670 nm and a full width at half-maximum of 1880 cm −1 (∼85 nm). The crystal structure was solved and refined from single-crystal X-ray diffraction data. This new compound from the group of the nitridolithoaluminates crystallizes in the orthorhombic space group Pnnm (No. 58) with the following unit-cell parameters: a = 10.4291(7) Å, b = 10.4309(7) Å, and c = 3.2349(2) Å. Sr 4 [LiAl 11 N 14 ]:Eu 2+ shows a pronounced tetragonal pseudo-symmetry. It consists of a framework of disordered (Al/ Li)N 4 and AlN 4 tetrahedra that are connected to each other by common corners and edges. Along the [001] direction, the tetrahedral network creates empty four-memberedring channels as well as five-membered-ring channels, in which the Sr 2+ cations are located.

Li 14 (PON 3 ) 2 O was synthesized by reaction of phosphoric triamide PO(NH 2 ) 3 with LiNH 2 at 550°C. It crystallizes in a trigonal structure [P3 (no. 147), a = 5.6880(5), c = 8.0855(8) Å, V = 226.55(5) Å 3 , Z = 1] that can be described as a defect variant of the antifluorite structure type. The crystal structure was elucidated from X-ray powder diffraction data and cor-