M2PO3N (M = Ca, Sr): ortho-Oxonitridophosphates with ß-K2SO4 Structure Type.

Two novel oxonitridophosphates M2PO3N with M = Ca and Sr were synthesized under high-pressure high-temperature (7 GPa and 1100 °C) using the multianvil technique or by solid-state reaction in the silica ampules (1100 °C) from amorphous phosphorus oxonitride (PON) and the respective alkaline earth oxides MO (M = Ca, Sr). The products represent the first examples of alkaline earth ortho-oxonitridophosphates containing noncondensed [PO3N](4-) ions. The crystal structures were elucidated by single-crystal X-ray diffraction. Sr2PO3N [space group Pnma (No. 62), Z = 4, a = 7.1519(5) Å, b = 5.5778(3) Å, c = 9.8132(7) Å, R1 = 0.020, wR2 = 0.047] crystallizes in the ß-K2SO4 structure type. The structure of Ca2PO3N was solved and refined in the (3 + 1)D superspace group Pnma(α00)0ss [Z = 4, a = 6.7942(7) Å, b = 5.4392(6) Å, c = 9.4158(11) Å, R1 = 0.041, wR2 = 0.067]. It exhibits an incommensurate modulation along [100] with a modulation vector q = [0.287(5), 0, 0]. Rietveld refinements support the structural models as well as the phase purity of the products. Upon doping with Eu(2+), Ca2PO3N exhibits luminescence in the green range (λem = 525 nm) of the visible spectrum if excited by near-UV light (λexc = 400 nm).

MH4P6N12 (M = Mg, Ca): new imidonitridophosphates with an unprecedented layered network structure type.

Isotypic imidonitridophosphates MH4P6N12 (M = Mg, Ca) have been synthesized by high-pressure/high-temperature reactions at 8 GPa and 1000 °C starting from stoichiometric amounts of the respective alkaline-earth metal nitrides, P3N5, and amorphous HPN2. Both compounds form colorless transparent platelet crystals. The crystal structures have been solved and refined from single-crystal X-ray diffraction data. Rietveld refinement confirmed the accuracy of the structure determination. In order to quantify the amounts of H atoms in the respective compounds, quantitative solid-state (1)H NMR measurements were carried out. EDX spectroscopy confirmed the chemical compositions. FTIR spectra confirmed the presence of NH groups in both structures. The crystal structures reveal an unprecedented layered tetrahedral arrangement, built up from all-side vertex-sharing PN4 tetrahedra with condensed dreier and sechser rings. The resulting layers are separated by metal atoms.

Luminescent nitridophosphates CaP2 N4 :Eu(2+) , SrP2 N4 :Eu(2+) , BaP2 N4 :Eu(2+) , and BaSr2 P6 N12 :Eu(2.).

Nitridophosphates MP2 N4 :Eu(2+) (M=Ca, Sr, Ba) and BaSr2 P6 N12 :Eu(2+) have been synthesized at elevated pressures and 1100-1300 °C starting from the corresponding azides and P3 N5 with EuCl2 as dopant. Addition of NH4 Cl as mineralizer allowed for the growth of single crystals. This led to the successful structure elucidation of a highly condensed nitridophosphate from single-crystal X-ray diffraction data (CaP2 N4 :Eu(2+) (P63 , no. 173), a=16.847(2), c=7.8592(16) Å, V=1931.7(6) Å(3) , Z=24, 2033 observed reflections, 176 refined parameters, wR2 =0.096). Upon excitation by UV light, luminescence due to parity-allowed 4f(6) ((7) F)5d(1) →4f(7) ((8) S7/2 ) transition was observed in the orange (CaP2 N4 :Eu(2+) , λmax =575 nm), green (SrP2 N4 :Eu(2+) , λmax =529 nm), and blue regions of the visible spectrum (BaSr2 P6 N12 :Eu(2+) and BaP2 N4 :Eu(2+) , λmax =450 and 460 nm, respectively). Thus, the emission wavelength decreases with increasing ionic radius of the alkaline-earth ions. The corresponding full width at half maximum values (2240-2460 cm(-1) ) are comparable to those of other known Eu(2+) -doped (oxo)nitrides emitting in the same region of the visible spectrum. Following recently described quaternary Ba3 P5 N10 Br:Eu(2+) , this investigation represents the first report on the luminescence of Eu(2+) -doped ternary nitridophosphates. Similarly to nitridosilicates and related oxonitrides, Eu(2+) -doped nitridophosphates may have the potential to be further developed into efficient light-emitting diode phosphors.

Ba3P5N10Br:Eu(2+): a natural-white-light single emitter with a zeolite structure type.

Illumination sources based on phosphor-converted light emitting diode (pcLED) technology are nowadays of great relevance. In particular, illumination-grade pcLEDs are attracting increasing attention. Regarding this, the application of a single warm-white-emitting phosphor could be of great advantage. Herein, we report the synthesis of a novel nitridophosphate zeolite Ba3P5N10Br:Eu(2+). Upon excitation by near-UV light, natural-white-light luminescence was detected. The synthesis of Ba3P5N10Br:Eu(2+) was carried out using the multianvil technique. The crystal structure of Ba3P5N10Br:Eu(2+) was solved and refined by single-crystal X-ray diffraction analysis and confirmed by Rietveld refinement and FTIR spectroscopy. Furthermore, spectroscopic luminescence measurements were performed. Through the synthesis of Ba3P5N10Br:Eu(2+), we have shown the great potential of nitridophosphate zeolites to serve as high-performance luminescence materials.

A high-pressure polymorph of phosphorus nitride imide.

Phosphorus nitride imide, PN(NH), is of great scientific importance because it is isosteric with silica (SiO2). Accordingly, a varied structural diversity could be expected. However, only one polymorph of PN(NH) has been reported thus far. Herein, we report on the synthesis and structural investigation of the first high-pressure polymorph of phosphorus nitride imide, ß-PN(NH); the compound has been synthesized using the multianvil technique. By adding catalytic amounts of NH4Cl as a mineralizer, it became possible to grow single crystals of ß-PN(NH), which allowed the first complete structural elucidation of a highly condensed phosphorus nitride from single-crystal X-ray diffraction data. The structure was confirmed by FTIR and (31)P and (1)H solid-state NMR spectroscopy. We are confident that high-pressure/high-temperature reactions could lead to new polymorphs of PN(NH) containing five-fold- or even six-fold-coordinated phosphorus atoms and thus rivalling or even surpassing the structural variety of SiO2.

Angular benzoperylenetetracarboxylic bisimides.

Benzoperylene derivatives with two angularly attached dicarboxylic imide rings, which were prepared by the Diels-Alder-reaction, exhibit strong fluorescence and their free peri positions allow either control of the UV/Vis spectra through their substituents or form anchor positions for the attachment of functional units. The angular chromophore 3 may be used both for fluorescent labeling such as for primary amines or enzymes or as building blocks for more complex assemblies where they may act as energy donors for FRET or electron acceptors in PET such as for photovoltaic solar cells.