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Amorphous titanium phosphate ion-exchangers are often of a “mixed type”, i.e., they contain a mixture of –HPO4 and –H2PO4 active groups. Their synthesis requires careful handling to obtain the same proportion of active units and sorption characteristics. This article focuses on the influence of titanium sources and post-synthetic treatments on the uniform synthesis of amorphous TiP1 (TiO(OH)(H2PO4)·H2O). It also describes a mild and straightforward method for obtaining crystalline α-TiP (Ti(HPO4)2·H2O). Amorphous TiP1 was successfully synthesized using five sources of titanium providing that the content of titanium and H2SO4 in the primary solution was 60–110 g L−1 and 400 ± 50 g L−1, respectively. Observations revealed that organic and inorganic acids could also be comparably used in post-synthetic treatments to protonate the phosphate groups into –H2PO4 units. The Na+ uptake (up to 7.2 meq g−1) and ion-exchange capacities towards divalent ions (up to 3.8 meq g−1) of all the TiP1-type sorbents studied are among the highest reported for TiP systems. Despite differences in the surface characteristics, the TiP1 materials synthesized in this study displayed comparable sorption properties, supporting the fact that chemisorption is the governing factor behind the sorption processes. Crystalline α-TiP is obtained under similar mild synthesis conditions when the P2O5 : TiO2 molar ratio is greater than 1 : 1, regardless of the titanium source. The possibility of using various types of TiOSO4 as a titanium source for TiP1 and α-TiP syntheses is emphasized and all reported data are re-considered from a synthetic perspective. [ABSTRACT FROM AUTHOR]

Helquat dyes combine a cationic hemicyanine with a helicene-like motif to form a new blueprint for chiral systems with large and tunable nonlinear optical (NLO) properties. We report a series of such species with characterization, including determination of static first hyperpolarizabilities β0 via hyper-Rayleigh scattering and Stark spectroscopy. The measured β0 values are similar to or substantially larger than that of the commercial chromophore E-4'-(dimethylamino)-N-methyl-4-stilbazolium. Density functional theory (DFT) and time-dependent DFT calculations on two of the new cations are used to probe their molecular electronic structures and optical properties. Related molecules are expected to show bulk second-order NLO effects in even nonpolar media, overcoming a key challenge in developing useful materials. [ABSTRACT FROM AUTHOR]

Abstract: The influence of concentrations of both TiO2 and H2SO4 in the syntheses of amorphous titanium phosphates (TiP) is reported. IR, XRD, TGA, BET and NMR techniques were used to characterise the isolated TiP products. The concentration of sulphuric acid in the initial synthesis plays a major role in the structural diversity and sorption properties of the final ionites. In the primary solutions, Ti(IV) is in monomeric, polymeric and colloidal forms. Upon addition of H3PO4 the presence of monomeric titanium ensures formation of the Ti(HPO4)2 phase. The polymeric Ti(IV) is responsible for formation of the titanium hydroxo-phosphate phase, Ti(OH)2(HPO4), whilst the colloidal form of Ti(IV) appears to have a role in coagulation of a minor Ti(OH)4 phase in an amorphous TiP. It is found that TiP ion-exchange capacities gradually increase with an increase of both TiO2 and H2SO4 concentrations and reach a maximum value of 3.8mg-eqg−1 when TiO2 is 70–100gL−1 and H2SO4 is 480–560gL−1. Analyses of compositional, structural and sorption data allowed 3D correlation diagrams to be built that can facilitate fabrication of TiP with tailored sorption properties. [Copyright &y& Elsevier]

Abstract: Decomposition of mineral sphene, CaTiOSiO4, by H3PO4 is investigated in detail. During the dissolution process, simultaneous calcium leaching and formation of titanium phosphate (TiP) take place. The main product of decomposition is a solid titanium phosphate–silica composite. The XRD, solid-sate NMR, IR, TGA, SEM and BET data were used to identify and characterize the composite as a mixture of crystalline Ti(HPO4)2·H2O and silica. When 80% phosphoric acid is used the decomposition degree is higher than 98% and calcium is completely transferred into the liquid phase. Formation of Ti(HPO4)2·H2O proceeds via formation of meta-stable titanium phosphate phases, Ti(H2PO4)(PO4)·2H2O and Ti(H2PO4)(PO4). The sorption affinities of TiP composites were examined in relation to caesium and strontium ions. A decrease of H3PO4 concentration leads to formation of composites with greater sorption properties. The maximum sorption capacity of TiP is observed when 60% H3PO4 is used in sphene decomposition. The work demonstrates a valuable option within the Ti(HPO4)2·H2O–SiO2 composite synthesis scheme, to use phosphoric acid flows for isolation of CaHPO4·2H2O fertilizer. [Copyright &y& Elsevier]

Amorphous titanium hydroxyphosphate with formula Ti(OH)1.36(HPO4)1.32 · 2.3H2O and a new silica-modified titanium hydroxyphosphate with a general formula Ti(OH)2x(HPO4)2-x · ySiO2 · nH2O are synthesized and characterized using IR, TG, XRD, SEM, solid-state NMR, and BET techniques, It is concluded that SiO2 is evenly distributed within the titanium phosphate (TiP) agglomerates and that neither the separate silica phase nor the titanium silicates are formed during the synthesis of silica-modified titanium hydroxyphosphate. Correlations between the texture, ion- exchange properties of the amorphous titanium hydroxyphosphate, and the amount of SiO2 present within the TiP matrix are established. Sorption properties of silica-modified titanium hydroxyphosphate toward Cs+ and Sr2+ are studied in a series of samples with an increasing amount of silica, at different pH, and in NaCI solutions with a varying ionic strength. It is found that sorption of Cs+ does not depend practically on the amount of SiO2 present, whereas the Sr2+ uptake drastically decreases with an increase of silica amount. The effects of pH and of the electrolyte concentration on the sorption behavior of titanium phosphate are discussed in terms of ionic hydration shell and titanium phosphate structural specificity. The kinetics of sorption processes is also investigated, and the diffusion coefficients for cesium and strontium are obtained. [ABSTRACT FROM AUTHOR]

Abstract: Polycrystalline octa-nuclear copper(I) O,O′-di-i-propyl- and O,O′-di-i-amyldithiophosphate cluster compounds, {Cu8[S2P(OR)2]6(μ8-S)} where R= i Pr and i Am, were synthesized and characterized by 31P CP/MAS NMR at 8.46T and static 65Cu NMR at multiple magnetic field strengths (7.05, 9.4 and 14.1T). The symmetries of the electronic environments around the P sites were estimated from the 31P chemical shift anisotropy (CSA) parameters, δ aniso and η. Analyses of the 65Cu chemical shift and quadrupolar splitting parameters for these compounds are presented with the data being compared to those for the analogous octa-nuclear cluster compounds with R= n Bu and i Bu. The 65Cu transverse relaxation for the copper sites in {Cu8[S2P(O i Pr)2]6(μ8-S)} and {Cu8[S2P(O i Am)2]6(μ8-S)} was found to be very different, with a relaxation time, T 2, of 590μs (Gaussian) and 90μs (exponential), respectively. The structures of {Cu4[S2P(O i Pr)2]4} and {Cu8[S2P(O i Pr)2]6(μ8-S)} cluster compounds in the liquid- and the solid-state were studied by Cu K-edge EXAFS. The disulfide, [S2P(O i Am)2]2, was obtained and characterized by 31P{1H} NMR. The interactions of the disulfide and of the potassium O,O′-di-i-amyldithiophosphate salt with the surfaces of synthetic chalcocite (Cu2S) were probed using solid-state 31P NMR spectroscopy and only the presence of copper(I) dithiophosphate species with the {Cu8[S2P(O i Am)2]6(μ8-S)} structure was observed. [Copyright &y& Elsevier]

Abstract: A polycrystalline copper(I) O,O′-di-n-butyldithiophosphate cluster compound, Cu8[S2P(O-n-Bu)2]6(μ8-S), was synthesized and characterized by 31P CP/MAS NMR at 8.46T and static 65Cu NMR at multiple magnetic field strengths (7.05, 9.4 and 14.1T). The principal values of the 31P chemical shift tensor and the 65Cu chemical shift and quadrupolar splitting parameters are presented. The data are compared to those for the analogous octa-nuclear cluster compounds [Cu8(S2P(OEt)2)6(μ8-S)], [Cu8(S2P(O-n-Pr)2)6(μ8-S)] and [Cu8(S2P(O-i-Bu)2)6(μ8-S)]. The transverse relaxation time constant, T 2, for the [Cu8(S2P(O-n-Bu)2)6(μ8-S)] cluster compound was found to be 160±8μs. Possible intra-molecular motions in the cluster structures in terms of size and branching of the hydrocarbon chains are discussed as reasons for the different 65Cu NMR responses of the systems. [Copyright &y& Elsevier]

Abstract: Polycrystalline tetra-nuclear Cu4[S2P(O-i-C3H7)2]4, hexa-nuclear Cu6[S2P(OC2H5)2]6, and octa-nuclear Cu8[S2P(O-i-C4H9)2]6(S) complexes were synthesized and analyzed by means of solid-state 31P CP/MAS and 65Cu static NMR spectroscopy. The symmetries of the electronic environments around each P-site were estimated from the 31P chemical shift anisotropy (CSA) parameters, Δ aniso and η. The 65Cu chemical shift and quadrupolar splitting parameters obtained from the experimental 65Cu NMR spectra of the polycrystalline CuI-complexes are presented. A solid-state NMR approach for the elucidation of the stereochemistry of poly-nuclear Cu(I) dithiophosphate complexes, when the structural analysis of the systems by single-crystal X-ray diffraction is not readily available, is proposed. [Copyright &y& Elsevier]

Correction for ‘Revisiting syntheses of Ti(iv)/H2PO4–HPO4 functional ion-exchangers, properties and features’ by Mylène Trublet et al., New J. Chem., 2017, DOI: 10.1039/c7nj03065g. [ABSTRACT FROM AUTHOR]

Fourteen new dipolar cations have been synthesized, containing methoxy or tertiary amino electron donor groups attached to helquat (Hq) acceptors. These Hq derivatives have been characterized as their TfO- salts by using various techniques including NMR and electronic absorption spectroscopies. UV-vis spectra show intense, relatively low energy absorptions with λmax ≈ 400-600 nm, attributable to intramolecular charge-transfer (ICT) excitations. Single-crystal X-ray structures have been solved for two of the chromophores, one as its PF6- salt, revealing centrosymmetric packing arrangements (space groups Pbca and P1-). Molecular quadratic nonlinear optical (NLO) responses have been determined directly by using hyper-Rayleigh scattering (HRS) with a 800 nm laser, and indirectly via Stark (electroabsorption) spectroscopy for the low energy absorption bands. The obtained static first hyperpolarizabilities β0 range from moderate to large: (9-140) × 10-30 esu from HRS in MeCN and (44-580) × 10-30 esu from the Stark data in PrCN. The magnitude of β0 increases upon either extending the π-conjugation length or replacing a methoxy with a tertiary amino electron donor substituent. Density functional theory (DFT) and time-dependent DFT calculations on selected tertiary amino chromophores confirm that the low energy absorptions have ICT character. Relatively good agreement between the simulated and experimental UV-vis absorption spectra is achieved by using the CAM-B3LYP functional with the 6-311G(d) basis set. The βtot values predicted by using DFT at the same level of theory are large ((472-1443) × 10-30 esu in MeCN). Both the theoretical and experimental results show that para-conjugation between Hq and electron donor fragments is optimal, and enlarging the Hq unit is inconsequential with respect to the molecular quadratic NLO response. [ABSTRACT FROM AUTHOR]

Three new dipolar cations have been synthesised, containing ferrocenyl (Fc) electron donor groups attached to helquat (Hq) acceptors. These organometallic Hq derivatives have been characterised as their TfO− salts by using various techniques including NMR and electronic absorption spectroscopies and electrochemical measurements. UV–vis spectra show multiple intense low energy absorptions attributable to intramolecular charge-transfer (ICT) excitations. Each compound displays a reversible Fc+/0 redox process, together with two reversible one-electron reductions of the Hq fragment. Molecular quadratic nonlinear optical (NLO) responses have been determined by using hyper-Rayleigh scattering at 1064 nm, and Stark (electroabsorption) spectroscopic studies on the visible absorption bands. The obtained first hyperpolarizabilities β are moderate, consistent with the relatively short π-conjugation lengths between the Fc and attached pyridinium group. A single-crystal X-ray structure has been solved for one of the complexes as its PF6− salt, revealing a centrosymmetric packing in the triclinic space group P1̅. Density functional theory (DFT) and time-dependent DFT calculations indicate that the lowest energy absorption bands have mainly metal-to-ligand charge-transfer character. The donor orbitals involved in the electronic transitions forming the next lowest energy ICT band also have substantial contributions from the Fe atom. Good agreement between the simulated and experimental UV–vis absorption spectra is achieved by using the PBE0 functional with the 6-311++G(d)/LANL2DZ mixed basis set, and the theoretical β values are reasonably large. Oxidation of the Fc unit is predicted to cause the βtot value to decrease by more than 80% in one of the complexes. [ABSTRACT FROM AUTHOR]

This work focuses on the synthesis of titanium phosphate (TiP1) ion-exchanger containing solely H 2 PO 4 -groups. Based on the elemental analyses, TG, 31 P MAS NMR, XRD and Raman data, the formula TiO(OH)(H 2 PO 4 )·H 2 O is assigned to TiP1. The synthesis requires a mild heating at 70–80 °C for a short period of time, followed by filtration and HCl-washing of the TiP1 powder. The layered nature and low crystallinity of this sorbent is confirmed by powder XRD technique. The existence of micro and mesopores in the material is established using BET method. The Na + capacity of TiP1 is determined to be 6.3 meq g −1 which is the highest value reported for H 2 PO 4 -based sorbents. The presence of H 2 PO 4 groups is expected to considerably increase both the pH-working range of the TiP1 sorbent and its exchange capacity towards divalent metal ions. All data for TiP1 are compared to the data for amorphous TiP containing mostly HPO 4 groups. [ABSTRACT FROM AUTHOR]

Four new complex salts [Ru11Cl(Tpm)(LA)2]- [PF6]n [Tpm = tris(l-pyrazolyl)methane; n - 1, LA = pyridine (py) 1 or ethyl isonicotinate (EIN) 2; n = 3, LA = N-methyl- 4,4'-bipyridinium (MeQ+) 3 or N-phenyl-4,4'-bipyridinium (PhQ+) 4] have been prepared and characterized. Electronic absorption spectra show intense d → μ* metal-to-ligand charge-transfer (MLCT) absorption bands, while cyclic voltammetry reveals a reversible RuIII/II wave, accompanied by quasireversible or irreversible LA based reductions for all except 1. Single crystal X-ray structures have been obtained for l•Me2CO, 2, and 3•Me2CO. For 2--4, molecular first hyperpolarizabilities ß have been measured in acetonitrile solutions via the hyper-Rayleigh scattering (HRS) technique at 800 nm. Stark (electroabsorption) spectroscopic studies on the MLCT bands in frozen butyronitrile allow the indirect estimation of static first hyperpolarizabilities ß0. The various physical data obtained for 3 and 4 are compared with those reported previously for related cis-{Ru11(NH3)4}2+ species [Coe, B. J. et al. J. Am. Chem. Soc. 2005, 127, 4845]. TD-DFT calculations on the complexes in 1--4 confirm that their lowest energy absorption bands are primarily Ru11 --> LA MLCT in character, while Ru11 → Tpm MLCT transitions are predicted at higher energies. DFT agrees with the Stark, but not the HRS measurements, in showing that ß0 increases with the electron-accepting strength of LA. The 2D nature of the chromophores is evidenced by dominant ßxxy tensor components. [ABSTRACT FROM AUTHOR]

New complexes with six ferrocenyl (Fc) groups connected to ZnII or CdII tris(2,2′-bipyridyl) cores are described. A thorough characterisation of their BPh4− salts includes two single-crystal X-ray structures, highly unusual for such species with multiple, extended substituents. Intense, visible d(FeII)→π* metal-to-ligand charge-transfer (MLCT) bands accompany the π→π* intraligand charge-transfer absorptions in the near UV region. Each complex shows a single, fully reversible FeIII/II wave when probed electrochemically. Molecular quadratic nonlinear optical (NLO) responses are determined by using hyper-Rayleigh scattering and Stark spectroscopy. The latter gives static first hyperpolarisabilities β0 reaching as high as approximately 10−27 esu and generally increasing with π-conjugation extension. Z-scan cubic NLO measurements reveal high two-photon absorption cross-sections σ2 of up to 5400 GM in one case. DFT calculations reproduce the π-conjugation dependence of β0, and TD-DFT predicts three transitions close in energy contributing to the MLCT bands. The lowest energy transition has octupolar character, whereas the other two are degenerate and dipolar in nature. [ABSTRACT FROM AUTHOR]