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Photoluminescence (PL) properties of YPO4:Mn2+ and Zr4+-doped YPO4:Mn2+ have been investigated by measuring PL and PL excitation (PLE) spectra and electron spin resonance (ESR) spectra. The PL spectrum at 9 K is dominated by a red (R) emission band at 1.91 eV for YPO4:Mn2+ and a blue-green (BG) emission band at 2.52 eV for YPO4:Zr4+,Mn2+. The R and BG bands are caused by the d–d transition in Mn2+ ions, in analogy with PL spectra of Mn2+-doped inorganic compounds. The PLE spectra for the R and BG bands are different from each other, suggesting that the Zr4+ addition changes the environment of Mn2+ ions. The ESR spectra revealed that Mn2+ ions can occupy interstitial sites without Zr4+ addition and Y3+ lattice sites with Zr4+ addition. It is thus supposed that the R and BG bands originate in an interstitial Mn2+ ion and a Y3+-substituted Mn2+ ion, respectively. The increase in the BG emission intensity caused by Zr4+ addition can be explained as an increase in the number of Mn2+ ions at Y3+ sites.

Photoluminescence of compounds that contain stoichiometric zirconium has been studied under vacuum ultraviolet excitation. The compounds show emission peaking at 280–320 nm while the excitation spectra show some bands in 130–190 nm region. The ultraviolet emission is explained as Zr to O charge transfer transition. The luminescence result and structural information classify the studied compounds into two groups. The former group involves ZrP 2 O 7 , CaZr(PO 4 ) 2 , NaZr 2 (PO 4 ) 3 , Ca 2 ZrSi 4 O 12 , Ca 3 ZrSi 2 O 9 and SrZrSi 2 O 7 , which show rather intense luminescence and do not have any infinite Zr–O–Zr–O–3D chain or link in their structure. The latter group is CaZrO 3 and ZrSiO 4 , which do contain infinite Zr–O–Zr–O–3D chain and show quite weak luminescence. Luminescence of Ca 1− x Mn x Zr(PO 4 ) 2 has also been studied. By replacing a part of Ca with Mn, ultraviolet emission of the host weakens and visible emission peaking at 540 nm appears. It is claimed that transfer of absorbed energy from Zr to Mn occurs.

The reaction of a nitrilotriacetate-intercalated Mg-Al layered double hydroxide in a lanthanum nitrate solution is studied. La3+ is incorporated into the interlayer through the formation of a chelate complex. NO3 − is also taken up as a charge-balancing anion. During chelation the interlayer repeat increases from 11.9 A to 13.9 A. Chemical analysis suggests that 1:1 and 1:2 metal:chelate complexes are formed within the interlayer. Calcination of the La3+-containing double hydroxide results in the formation of LaAlO3.

The formation, by coprecipitation, of a Mg-Al layered double hydroxide (LDH) intercalate containing nitrilotriacetate (NTA) anions has been observed. The intercalated LDH has a basal spacing close to 12 A (gallery height 7.2 A). The rehydration of a Mg-Al mixed oxide (formed by calcination at 500 °C of a Mg-Al carbonate-containing LDH) in the presence of NTA also results in the formation of a NTA intercalated LDH, indicating the ability of the mixed oxide for adsorptive removal of NTA. It was further shown that nitrate-containing LDHs may be ion-exchanged by NTA, whereas for carbonate-containing materials exchange is difficult. In some cases the formation of the intercalate is accompanied by considerable sequestration of the magnesium and aluminium cations. It is proposed that NTA may exist in the interlayer of the LDH as a trivalent or a divalent anion or under certain circumstances as a [Mg-NTA] – complex.

The temperature dependence of the time-integrated intensity of afterglow in SrAl 2 O 4 :Eu,Dy and SrAl 2 O 4 :Eu phosphors has been investigated by using UV light from a deuterium lamp. The time-integrated intensity of afterglow in SrAl 2 O 4 :Eu,Dy increases at around 150 K with temperature, and reaches the maximum at around 270 K. These results are compared with those for SrAl 2 O 4 :Eu, and the function of Dy 3+ ions is discussed in connection with the creation of hole traps.

The exchange of interlayer terephthalate (TA) anions from a Mg–Al layered double hydroxide (LDH) by carbonate, sulfate, chloride and nitrate anions is reported. It is shown that TA is readily exchanged by CO 3 2− and SO 4 2− but only partly by Cl − and NO 3 − . We demonstrate that during the exchange process interstratified phases are observed. Such interstratification has previously been reported only for directly synthesised materials. The origin of the interstratification is believed to be associated with two preferred orientations of TA anions within the layers, i.e. vertical or horizontal to the clay sheets. Two models for the possible exchange mechanism which is operating in these systems are proposed.

The interactions of the following three kinds of racemic and enantiomeric cobalt(III) chelates with montmorillonite and saponite are studied: (Co(en)3) 3§ (en = ethylenediamine), (Co(diNOsar)) 3+ (diNOsar = (1,8-dinitro-3,6,10,13,16,19-hexaazabicyclo(6,6,6)-eicosane)cobalt(III)) and (Co(diAMsar)) 3+ (diAMsar = (1,8-diamino-3,6,10,13,16,19-hexaazabicyclo-(6,6,6)eicosane)-cobalt(III)). At neutral pH, these complexes are adsorbed as a trivalent cation up to 90%-100% of the cation exchange capacity of a clay. No difference is observed in the maximum adsorption amount between the racemic and enantiomeric isomers. The basal spacings of the clay-chelate adducts are determined by the X-ray diffraction mea- surements of non-oriented powder samples: 14.3 ~, for (Co(en)3) 3+ montmorillonite, 16.5 ~ for (Co(diNOsar)) 3+ montmorillonite, and 16.9 A for (Co(diAMsar)) 3+ montmorillonite. The results imply that the chelates form a monolayer in the interlayer space. From the one-dimensional Fourier analyses of the diffraction pattern of (Co(diNOsar)) 3+ montmorillonite, the chelate is concluded to be adsorbed with its three-fold symmetry axis in parallel with the layer surface. This is in contrast with the previous results of (Ru(phen)3) 2§ and (Ru(bpy)3) 2+, which are adsorbed with their three-fold symmetry axes per- pendicular to the surface. The conclusion is consistent with the angular dependence of the infrared absorption spectrum of the film of the adduct.

In the title compound, triaqua-μ-nitrilotriacetato-magnesiumsodium dihydrate, [MgNa(C 6 H 6 NO 6 )(H 2 O) 3 ].2H 2 O, a nitrilotriacetate ligand chelates one Mg atom via three Mg-O bonds and one Mg-N bond. Each ligand also binds to two Na atoms and another Mg atom such that an infinite layer of stoichiometry MgNa(C 6 H 6 NO 6 )(H 2 O) 3 is formed. Adjacent layers are bound via hydrogen bonds with two interlayer water molecules.

An apparatus for measuring stopped-flow electric dichroism is constructed. The instrument enables one to measure electric dichroism as a function of time after two solutions are mixed within 6 ms. The adsorption of enantiomeric or racemic [Ru(phen) 3 ] 2+ (phen=1,10-phenanthroline) by colloidally dispersed montmorillonite is studied with this instrument. As a result, it is confirmed that the adsorption of racemic [Ru(phen) 3 ] 2+ occurs by way of two successive paths: first the chelate binds with a clay rapidly within the cation-exchange capacity (CEC) and then it is adsorbed slowly in excess over the CEC

Novel UV and blue phosphors, YPO 4 :Zr and YPO 4 :Zr,Mn, respectively, are synthesized and investigated. YPO 4 :Zr shows the emission about 290 nm assigned to the charge transfer transition of O-Zr. The excitation spectrum of the emission has main band peaked at 175 nm. The codoped phosphor YPO 4 :Zr,Mn shows the emission peaked at 477 nm assigned to the d-d transition of Mn 2 + within 3d 5 configuration. The excitation bands of the blue emission are around 152 and 193 nm. YPO 4 :Mn does not show any emission and the 290 nm emission observed for YPO 4 :Zr is diminished for YPO 4 :Zr,Mn. It is suggested that Zr plays an important role in the excitation of the Mn blue emission of YPO 4 :Zr,Mn. The emission wavelength of YPO 4 :Zr,Mn is remarkably short compared with the usual Mn 2 + activated phosphors.

The mechanism of sulfur inversion in some platinum(II)–thioether complexes was reinvestigated with the use of the dynamic NMR technique. Activation parameters for the sulfur inversion in [(isopropylthio)acetato-O,S]bis(triphenylphosphine)platinum(II) perchlorate in CDCl3 were obtained by taking advantage of the line shape changes in its 1H NMR spectra at various temperatures as follows: ΔH\eweq 18.0±0.4 kcal mol−1, ΔS\eweq 4.0±1.4 cal mol−1 K−1. The kinetic parameters varied little, though the rates of inversion were determined in other solvents. The entropy of activation and the solvent effects together with the presence of coupling between the phosphine-31P and the methine-1H throughout the temperature range of investigation evidence the sulfur inversion without breaking the Pt–S bond. The sulfur inversion in dichlorobis(dialkyl sulfide)platinum(II) in nonpolar solvents was also concluded to take place without bond breakage.