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Two Sn(IV) corroles were synthesized and electrochemically examined. The investigated compounds are represented as (OEC)Sn(C(6)H(5)) and (OEC)SnCl, where OEC = trianion of 2,3,7,8,12,13,17,18-octaethylcorrole. (OEC)Sn(C(6)H(5)) represents the first example of a sigma-bonded metallocorrole which does not undergo a metal-centered electrode reaction. Both compounds undergo three reversible one-electron oxidations, all of which occur at the conjugated macrocycle. The reduction of (OEC)SnCl involves an overall two electrons, with the product being spectroscopically identified as a Sn(II) corrole after bulk electrolysis of the starting compound. (OEC)Sn(C(6)H(5)) is reversibly reduced by a single electron to give a Sn(IV) corrole pi-anion radical. The electrochemically measured HOMO-LUMO gap (defined as the absolute potential difference between the first-ring centered reduction and first ring-centered oxidation) is equal to 2.25 V in benzonitrile, a value which closely approximates what is observed for porphyrins containing octaethylporphyrin (OEP) or tetraphenylporphyrin (TPP) macrocycles. An X-ray crystallographic analysis for the molecular structure of (OEC)Sn(C(6)H(5)) is also presented: monoclinic, P2(1)/n, with a = 13.235(4) Å, b = 14.502(4) Å, c = 18.387(5) Å, beta = 95.45(2) degrees, Z = 4, R = 0.0619.

The electrochemical behavior of (TPPBrx)Co (TPPBrx = the dianion of β-brominated-pyrrole tetraphenylporphyrin and x = 0−8) is reported under an N2 or a CO atmosphere in dichloromethane containing tetra-n-butylammonium hexafluorophosphate as supporting electrolyte. Each investigated compound undergoes three reversible one-electron oxidations within the potential window of the solvent, and this results in the ultimate formation of a cobalt(III) dication as the final three-electron-oxidation product under both an N2 and a CO atmosphere. The initial one-electron abstraction from (TPPBrx)Co involves the central metal ion for derivatives with x ≤ 5 and the conjugated porphyrin π ring system for derivatives with six, seven, or eight Br groups. Thin-layer infrared spectroelectrochemical measurements were performed during the first oxidation of (TPPBrx)Co in dichloromethane and indicate that in situ generated [(TPPBrx)Co]+ forms mono- and bis(carbon monoxide) adducts for complexes with zero to five Br groups but t...

A series of single-component red/white-emitting CaScAlSiO6:Ce(3+),Tb(3+),Mn(2+) phosphors have been synthesized by a solid-state reaction. It is observed that CaScAlSiO6:Ce(3+),Tb(3+) phosphors exhibit two dominating bands situated at 380 and 542 nm, originating from the allowed 5d → 4f transition of the Ce(3+) ion and the (5)D4 → (7)F(J) = (J = 6, 5, 4, 3) transition of the Tb(3+) ion, respectively. As for CaScAlSiO6:Ce(3+),Mn(2+), our results indicate that Mn(2+) may occupy not only a Ca(2+) site to generate an orange emission [Mn(2+)(I)] at 590 nm but also a Sc(3+) site to generate a red emission [Mn(2+)(II)] at 670 nm. Both energy transfers from Ce(3+) to Tb(3+) and from Ce(3+) to Mn(2+) in the CaScAlSiO6 host are investigated and have been demonstrated to be of the resonant type via a dipole-dipole mechanism. By proper tuning of the relative composition of Tb(3+)/Mn(2+), white light can also be achieved upon excitation of UV light, indicating that the developed phosphor may potentially be used as a single-component red/white-emitting phosphor for UV-light-emitting diodes.

Gd(2)O(2)S:Ln(3+) (Ln = Eu, Tb) submicrospheres were successfully prepared through a facile and mild solvothermal method followed by a subsequent heat treatment. X-ray diffraction (XRD) results demonstrate that all the diffraction peaks of the samples can be well indexed to the pure hexagonal phase of Gd(2)O(2)S. The energy dispersive spectroscopy (EDS), element analysis, and FT-IR results show that the precursors are composed of the Gd, Eu, O, S, C, H, and N elements. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results show that these spheres are actually composed of randomly aggregated nanoparticles. The formation mechanism for the Gd(2)O(2)S:Ln(3+)(Ln = Eu, Tb) spheres has been proposed on an isotropic growth mechanism. Under ultraviolet excitation, Gd(2)O(2)S:Ln(3+)(Ln = Eu, Tb) spheres show red and green emission corresponding to the (5)D(0)→(7)F(2) transition of the Eu(3+) ions and the (5)D(4)→(7)F(5) transition of the Tb(3+) ions. Furthermore, this synthetic route may have potential applications for fabricating other lanthanide oxysulfides.

A novel white-light-emitting phosphor Ca(9)Lu(PO(4))(7):Eu(2+),Mn(2+) has been prepared by solid-state reaction. The photoluminescence properties indicate that there is an efficient energy transfer from the Eu(2+) to Mn(2+) ions via a dipole-quadrupole reaction. The obtained phosphor exhibits a strong excitation band between 250 and 430 nm, matching well with the dominant emission band of a UV light-emitting-diode (LED) chip. Upon excitation of UV light, white light is realized by combining a broad blue-green emission band at 480 nm and a red emission band at 645 nm attributed to the Eu(2+) and Mn(2+) ions. The energy-transfer efficiency and critical distance were also calculated. Furthermore, the phosphors can generate lights from blue-green through white and eventually to red by properly tuning the relative ratio of the Eu(2+) to Mn(2+) ions through the principle of energy transfer. Preliminary studies showed that the phosphor might be promising as a single-phased white-light-emitting phosphor for a UV white-light LED.

Large-scale good-quality submicrometer-sized YPO(4):Eu(3+) hollow spheres were synthesized by utilizing the colloidal spheres of Y(OH)CO(3):Eu(3+) as a sacrificial template and NH(4)H(2)PO(4) as a phosphorus source, for the first time. The whole process mainly consists of the hydrothermal reaction and acid erosion. The YPO(4):Eu(3+)@Y(OH)CO(3):Eu(3+) core-shell structures were first obtained after the hydrothermal process. Then, the remaining Y(OH)CO(3):Eu(3+) was removed by selective dissolution in a dilute nitric acid solution. The YPO(4):Eu(3+) hollow spheres were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL). The formation mechanism was also investigated. The obtained YPO(4):Eu(3+) hollow spheres may have potential applications in cell biology, drug release, and diagnosis, due to high chemical stability and luminescence functionality.

Several cobalt nitrosyl porphyrins of the form (T(p/m-X)PP)Co(NO) (p/m-X = p-OCH(3) (1), p-CH(3) (2), m-CH(3) (3), p-H (4), m-OCH(3) (5), p-OCF(3) (6), p-CF(3) (7), p-CN (8)) have been synthesized in 30-85% yields by reaction of the precursor cobalt porphyrin with nitric oxide. Compounds 1-7 were also prepared by reaction of the precursor cobalt porphyrin with nitrosonium tetrafluoroborate followed by reduction with cobaltocene. Compounds 1-8 have been characterized by elemental analysis, IR and (1)H NMR spectroscopy, mass spectrometry, and UV-vis spectrophotometry. They are diamagnetic and display nu(NO) bands in CH(2)Cl(2) between 1681 and 1695 cm(-)(1). The molecular structure of 1, determined by a single-crystal X-ray crystallographic analysis, reveals a Co-N-O angle of 119.6(4) degrees. Crystals of 1 are monoclinic, P2/c, with a = 15.052(1) A, b = 9.390(1) A, c = 16.274(2) A, beta = 111.04(1) degrees, V = 2146.8(4) A(3), Z = 2, T = 228(2) K, D(calcd) = 1.271 g cm(-)(3), and final R1 = 0.0599 (wR2 = 0.1567, GOF = 1.054) for 3330 "observed" reflections with I >/= 2sigma(I). Cyclic voltammetry studies in CH(2)Cl(2) reveal that compounds 1-7 undergo two reversible oxidations and two reversible reductions at low temperature. This is not the case for compound 8, which undergoes two reversible reductions but an irreversible oxidation due to adsorption of the oxidized product onto the electrode surface. Combined electrochemistry-infrared studies demonstrate that each of the compounds 1-7 undergoes a first oxidation at the porphyrin pi ring system and a first reduction at either the metal center or the nitrosyl axial ligand. The formulation for the singly oxidized products of compounds 1-7 as porphyrin pi-cation radicals was confirmed by the presence of bands in the 1289-1294 cm(-)(1) region (for compounds 1-5), which are diagnostic IR bands for generation of tetraarylporphyrin pi-cation radicals.