Shoulder Band Research Articles

Complex Alternative Cytoplasmic Protein Isoforms of the Kaposi's Sarcoma-Associated Herpesvirus Latency-Associated Nuclear Antigen 1 Generated through Noncanonical Translation Initiation

Kaposi's sarcoma-associated herpesvirus (KSHV) latency associated-nuclear antigen 1 (LANA1) protein is constitutively expressed in all KSHV-infected cells, as well as in all forms of KSHV-associated malignancies. LANA1 is a multifunctional KSHV oncoprotein containing multiple repeat sequences that is important for viral episome maintenance and the regulation of cellular and viral gene expression. We characterize here multiple LANA1 isoforms and show that ∼50% of LANA1 is naturally generated as N-terminally truncated shoulder proteins that are detected on SDS-PAGE as faster-migrating shoulder bands designated LANA1(S). Higher-molecular-weight LANA1(S) isoforms initiate downstream at noncanonical sites within the N-terminal region, whereas lower-molecular-weight LANA1(S) isoforms initiate downstream within the central repeat 1 domain. LANA1(S) proteins lack an N-terminal nuclear localization signal motif, and some isoforms differ from full-length, canonical LANA1 by localizing to perinuclear and cytoplasmic sites. Although LANA1 has until now been assumed to be solely active in the nucleus, this finding indicates that this major KSHV oncoprotein may have cytoplasmic activities as well. KSHV overcomes its limited genetic coding capacity by generating alternatively initiated protein isoforms that may have distinct biological functions.

Raman spectroscopy and crystal-field split rotational states of photoproducts CO and H2 after dissociation of formaldehyde in solid argon

Raman signal is monitored after 248 nm photodissociation of formaldehyde in solid Ar at temperatures of 9-30 K. Rotational transitions J = 2 ← 0 for para-H(2) fragments and J = 3 ← 1 for ortho-H(2) are observed as sharp peaks at 347.2 cm(-1) and 578.3 cm(-1), respectively, which both are accompanied by a broader shoulder band that shows a split structure. The rovibrational spectrum of CO fragments has transitions at 2136.5 cm(-1), 2138.3 cm(-1), 2139.9 cm(-1), and 2149 cm(-1). To explain the observations, we performed adiabatic rotational potential calculations to simulate the Raman spectrum. The simulations indicate that the splitting of rotational transitions is a site effect, where H(2) molecules can reside in a substitution site, in addition to an interstitial site. In the former site, rotational motion is unperturbed by the electrostatic field of the host atoms, while the latter site splits the excited rotational manifolds, J = 2 and 3, into doublet and triplet structures, respectively. For CO, the spectrum can be ascribed to monomeric species in single- and double-substitution sites, to a dimeric species (CO)(2), and to a CO-H(2)O complex. The simulations show that a nearest-neighbor molecular complex CO-H(2) is not responsible for any of the observed spectral fingerprints. The cause of the exit of the molecular hydrogen from the initial cage can be traced to high translational energy of the fragment after the photodissociation. After the matrix has reached a thermal equilibrium, a diffusion driven formation of the complex is possibly hindered by the high rotational zero-point energy developed upon complexation.

Cyclometalated Iridium(III) Complexes Containing Hydroxide/Chloride Ligands: Isolation of Heterobridged Dinuclear Iridium(III) Compounds Containing μ-OH and μ-Pyrazole Ligands

The reaction of the cyclometalated chloro-bridged iridium(III) dimers [(ppy)(2) Ir(μ-Cl)](2) (ppyH = 2-phenyl pyridine) and [(tpy)(2)Ir(μ-Cl)](2) (tpyH = 2-p-tolylpyridine) with 3,5-diphenylpyrazole (Ph(2)PzH) in the presence of sodium methoxide resulted in the formation of heterobridged dimers [(ppy)(2)Ir(μ-OH)(μ-Ph(2)Pz)Ir(ppy)(2)] (1) and [(tpy)(2)Ir(μ-OH)(μ-Ph(2)Pz)Ir(tpy)(2)] (2). Interestingly, the reaction of [(ppy)(2)Ir(μ-Cl)](2) with 3(5)-methyl-5(3)-phenylpyrazole (PhMePzH) afforded both a heterobridged dimer, [(ppy)(2)Ir(μ-OH)(μ-PhMePz)Ir(ppy)(2)] (3), and the monomer [(ppy)(2)Ir(PhMePz)Cl] (4). The compound [(ppy)(2)Ir(PhMePz)OH] (5) containing a terminal OH was obtained in a hydrolysis reaction involving 4, sodium methoxide, and PhMePzH. Complexes 1-5 were characterized by X-ray crystallography and electrospray ionization high-resolution mass spectrometry. All of the complexes are luminescent at room temperature in their dichloromethane solutions. The luminescence of the dinuclear complexes is characterized by a single structureless band centered at λ(max) = 550 nm (1 and 3) and 546 nm (2). The emission spectra of the mononuclear complexes 4 and 5 display vibronic structures with their λ(max) values at 497 nm (4) and 513 nm (5). In each case, the main emission bands are accompanied by shoulder bands at 526 (4) and 534 nm (5). The quantum yields, calculated with reference to [Ir(ppy)(2)(bpy)]PF(6) (Φ(CH(3)CN) = 0.0622), range from 0.11 to 0.17 for the dinuclear complexes and 0.045 to 0.048 for the mononuclear complexes. The lifetimes of the emission are in the microsecond region, suggesting the phosphorescent nature of the emission. Density functional theory (DFT) and time-dependent DFT calculations were performed on complexes 1 and 4 in the ground state to gain insight into the structural, electronic, and photophysical properties. Electrochemical studies on complexes 1-3 showed the presence of two consecutive one-electron-oxidation processes, assigned as the stepwise oxidation of the two Ir(III) centers, i.e., Ir(III)-Ir(III)/Ir(III)-Ir(IV) and Ir(III)-Ir(IV)/Ir(IV)-Ir(IV) couples, respectively. The monomers displayed single-oxidation peaks. No reduction process was observed within the solvent cathodic potential limit.

Vibrational spectroscopic study of the minerals nekoite Ca3Si6O15·7H2O and okenite Ca10Si18O46·18H2O – Implications for the molecular structure

Nekoite Ca3Si6O15·7H2O and okenite Ca10Si18O46·18H2O are both hydrated calcium silicates found respectively in contact metamorphosed limestone and in association with zeolites from the alteration of basalts. The minerals form two-dimensional infinite sheets with other than six-membered rings with 3-, 4-, or 5-membered rings and 8-membered rings. The two minerals have been characterised by Raman, near-infrared and infrared spectroscopy. The Raman spectrum of nekoite is characterised by two sharp peaks at 1061 and 1092cm−1 with bands of lesser intensity at 974, 994, 1023 and 1132cm−1. The Raman spectrum of okenite shows an intense single Raman band at 1090cm−1 with a shoulder band at 1075cm−1. These bands are assigned to the SiO stretching vibrations of Si2O5 units. Raman water stretching bands of nekoite are observed at 3071, 3380, 3502 and 3567cm−1. Raman spectrum of okenite shows water stretching bands at 3029, 3284, 3417, 3531 and 3607cm−1. NIR spectra of the two minerals are subtly different inferring water with different hydrogen bond strengths. By using a Libowitzky empirical formula, hydrogen bond distances based upon these OH stretching vibrations. Two types of hydrogen bonds are distinguished: strong hydrogen bonds associated with structural water and weaker hydrogen bonds assigned to space filling water molecules.

Modifications of the optical properties in Makrofol-E SSNTD exposed to ultraviolet radiation of different wavelengths

The induced modifications of the optical properties in UV-irradiated Makrofol-E with different wavelengths were investigated. Makrofol-E samples were irradiated by UV of wavelengths 254, 302, and 365 nm for different durations. It was found that Makrofol-E shows substantial modifications in its optical characteristics upon exposure to UV of wavelengths 302 and 254 nm, but no modifications were observed at 365 nm. UV-irradiated Makrofol-E with wavelengths 254 and 302 nm exhibits shoulder bands at 297 nm in UV–visible spectra. For an exposure time less than 20 h, the band absorbance strengths depend on the exposure time and approximately increases linearly, but for prolonged exposure times, the band absorbance strengths become almost saturated. The optical energy band gaps obtained from the direct and indirect allowed transition in K-space. Both of them decrease with the increase in exposure time for wavelengths of 254 and 302 nm. Urbach's energy increases with increase in the exposure time for both wavelengths of 254 and 302 nm. The number of carbon atoms in a cluster increases with the increase in the exposure time.

Dislocation and Elastic Strain in an InN Film Characterized by Synchrotron Radiation X-Ray Diffraction and Rutherford Backscattering/Channeling

Dislocation information and strain-related tetragonal distortion as well as crystalline qualities of a 2-μm-thick InN film grown by molecular beam epitaxy (MBE) are characterized by Rutherford backscattering/channeling (RBS/C) and synchrotron radiation x-ray diffraction (SR-XRD). The minimum yield χmin = 2.5% deduced from the RBS/C results indicates a fairly good crystalline quality. From the SR-XRD results, we obtain the values of the screw and edge densities to be ρscrew = 7.0027 × 109 and ρedge = 8.6115 × 109 cm−2, respectively. The tetragonal distortion of the sample is found to be −0.27% by angular scans, which is close to the −0.28% derived by SR-XRD. The value of |e⊥/e∥| = 0.6742 implies that the InN layer is much stiffer along the a axis than that along the c axis, where e∥ is the parallel elastic strain, and e⊥ is the perpendicular elastic strain. Photoluminescence results reveal a main peak of 0.653 eV with the linewidth of 60 meV, additional shoulder band could be due to impurities and related defects.

Red- and white-emitting organic light-emitting diodes based on trimetallic dendritic europium (III) complex: Eu3(DBM)9(TMMB)

The photoluminescence (PL) and electroluminescence (EL) properties of a trimetallic dendritic europium (III) complex containing three metal cores as branching centers, tris(dibenzoylmethanato) (1,3,5-tris[2-(2′-pyridyl)benzimidazoly]methyl-benzene)-europium (III) (Eu3(DBM)9(TMMB)), have been investigated and reported. Red and white emissions have been acquired in the four EL devices of device A–D. Characteristic red emission peaking at 613nm with four shoulder bands due to the 5D0→7Fj (j=0–4) transitions of Eu3(DBM)9(TMMB) is observed in devices A–C. Device D with a simple non-doping device structure showed a white emission band. Also, the optical and the electrochemical properties of Eu3(DBM)9(TMMB) have been characterized to possess a better understanding on the intramolecular energy transfer process. It is concluded that dendritic structure with three DBM ligands as “absorption antennas” facilitates the energy absorption and transportation of the complex.

Synthesis, Characterization and its Photoluminescence Properties of Group I-III-VI2 CuInS2 nanocrystals

Abstract We report the synthesis, characterization, and photoluminescence (PL) properties of colloidal I-III-VI2 CuInS2 and CuInS2/ZnS nanocrystals (NCs). Absorption shoulder and PL bands of the NCs are located at higher energy than those of band gap energy of bulk crystals due to a quantum-confinement effect. The PL band has a relatively large Stokes-shift, broad linewidth, and long decay-time, which suggests that the PL originates from a recombination of confined-excitions associated with donor(s) and/or acceptor(s). We found that quantum yield of the PL depends strongly on the photon-energy of excitation light and that it is up to 40-50% in resonant excitation at the energy positions corresponding to the absorption shoulder. Detailed properties and possible dynamics will be described. We also present preliminary results of PL properties focused on single NCs. There exist highluminescent NCs exhibiting so-called PL blinking as similar with II-VI NCs, while the others are dark NCs. 73.21.La, 78.47.jd, 78.67.Bf, 78.67.Hc

Quality of Brazilian vegetable oils evaluated by (modulated) differential scanning calorimetry

Vegetable oils are increasingly replacing fossil- oil-based polymers, and therefore aimed at being used in polymerization reactions from -20 to 100 � C. Therefore, phase transitions and heat capacities in this temperature range should be well characterized to optimize processing conditions and energy inputs. By using the DSC analysis, only small primary correspondence or divergence between different oil types are seen as a function of their degree of unsaturation, but it does not clearly distinguish detailed features such as shoulder bands related to the separate melting processes of single fatty acid components. By using modulated DSC analysis, the combined analysis of reversing and non-reversing heat signals provides better results. The latter confirms that the melting is not a phys- ical one-step process, but equilibrates between phase transitions and enthalpic reorganizations of the fatty acids that can be monitored separately. The specific heat capacities measured during modulated DSC are somewhat lower than traditional calorimetric measurements, but relate to the degree of unsaturation. The thermal behavior of palm-, soy-, sunflower-, corn-, castor-, and rapeseed-oil is discussed in relation to their composition, by applying a first or second heating scan.

Biomolecule-Assisted Green Route to Sb<SUB>2</SUB>S<SUB>3</SUB> Crystals with Three-Dimensional Dandelionlike Patterns

This paper describes a simple biomolecule-assisted solvothermal approach to fabricate the three-dimensional (3D) Sb2S3 microsphere with a wealth of novel morphologies in the presence of L-cysteine, which served as both the sulfur source and the directing molecule in the formation of antimony sulfide nanostructures. The effects of different solvents, and polyvinylpyrrolidone (PVP) on the morphology, structure, and phase composition of the as-prepared Sb2S3 products were discussed. The formation of 3D dandelionlike Sb2S3 microsphere was probably via the mechanism of the orientated aggregation growth of the Sb2S3 particles under the complexing action of L-cysteine, and co-action of the surfactant PVP. The absorption spectra of as-prepared 3D dandelionlike Sb2S3 structures show an optical shoulder band gap of 1.81 eV, which is near to the optimum for photovoltaic conversion.

A vibrational spectroscopic study of the mixed anion mineral sanjuanite Al 2(PO 4)(SO 4)(OH)·9H 2O

The mineral sanjuanite Al 2(PO 4)(SO 4)(OH)·9H 2O has been characterised by Raman spectroscopy complimented by infrared spectroscopy. The mineral is characterised by an intense Raman band at 984 cm −1, assigned to the (PO 4) 3− ν 1 symmetric stretching mode. A shoulder band at 1037 cm −1 is attributed to the (SO 4) 2− ν 1 symmetric stretching mode. Two Raman bands observed at 1102 and 1148 cm −1 are assigned to (PO 4) 3− and (SO 4) 2− ν 3 antisymmetric stretching modes. Multiple bands provide evidence for the reduction in symmetry of both anions. This concept is supported by the multiple sulphate and phosphate bending modes. Raman spectroscopy shows that there are more than one non-equivalent water molecules in the sanjuanite structure. There is evidence that structural disorder exists, shown by the complex set of overlapping bands in the Raman and infrared spectra. At least two types of water are identified with different hydrogen bond strengths. The involvement of water in the sanjuanite structure is essential for the mineral stability.

Raman spectroscopy of newberyite Mg(PO 3OH)·3H 2O: A cave mineral

Newberyite Mg(PO 3OH)·3H 2O is a mineral found in caves such as from Moorba Cave, Jurien Bay, Western Australia, the Skipton Lava Tubes (SW of Ballarat, Victoria, Australia) and in the Petrogale Cave (Madura, Eucla, Western Australia). Because these minerals contain oxyanions, hydroxyl units and water, the minerals lend themselves to spectroscopic analysis. Raman spectroscopy can investigate the complex paragenetic relationships existing between a number of ‘cave’ minerals. The intense sharp band at 982 cm −1 is assigned to the PO 4 3− ν 1 symmetric stretching mode. Low intensity Raman bands at 1152, 1263 and 1277 cm −1 are assigned to the PO 4 3− ν 3 antisymmetric stretching vibrations. Raman bands at 497 and 552 cm −1 are attributed to the PO 4 3− ν 4 bending modes. An intense Raman band for newberyite at 398 cm −1 with a shoulder band at 413 cm −1 is assigned to the PO 4 3− ν 2 bending modes. The values for the OH stretching vibrations provide hydrogen bond distances of 2.728 Å (3267 cm −1), 2.781 Å (3374 cm −1), 2.868 Å (3479 cm −1), and 2.918 Å (3515 cm −1). Such hydrogen bond distances are typical of secondary minerals. Estimates of the hydrogen-bond distances have been made from the position of the OH stretching vibrations and show a wide range in both strong and weak bonds.

Structure and optical spectra of bis(pyrrol-2-ylmethyleneamine) complexes: A DFT and TDDFT study of the self-assembly complexes of bis(pyrrol-2-ylmethyleneamine) ligands linked by alkyl spacers with Cu(II)

The UV-Vis absorption spectra of self-assembly Cu (II) complexes for bis(pyrrol-2-ylmethyleneamine) linked by alkyl(CH2)n(n = 2,3,4,6) spacers were recorded. The ground-state geometries and electronic structures were investigated by density functional theory employing generalized-gradient approximation Perdew-Burke-Ernzerhof (PBE) and hybrid B3LYP (20% Ex,HF)and PBE0 (25% Ex,HF) functional, in conjugation with four basis set combinations.[BS1:6-31G(d); BS2:Lanl2dz for Cu and 6-31G(d) for C,H,N; BS3:6-31+G(d); BS4:6-311+G(d,p) for C,H,N and Lanl2dz for Cu]. Compared the optimized geometries with XRD structures, it was found that the choice of methods appeared to have a more pronounced effect on structure than that of the basis set. PBE0/BS4 optimized geometries provide the best agreement with XRD experimental results and the mean absolute errors for bond length is 0.018 A and for bond angle is 2.1°. Transition excited states of complexes 1–4 in the gas phase and in CH2ClCH2Cl solution have been studied by the time-dependent density functional theory in conjugated with the Polarizable Continuum Model. Pure PBE and hybrid B3LYP, PBE0 functionals, as well as BS1, BS2, and BS5 [6-311++G (d,p)] were selected. Calculations indicate that PBE functional provides more accurate descriptions on main UV-vis absorptions than B3LYP and PBE0 functionals. The strongest absorption bands located at 338–356 nm are due to intraligand charge transfer (ILCT) transitions, a mixed-character ILCT + metal-ligand charge transfer (MLCT) absorptions are calculated at 280–291 nm, the shoulder bands located at 250–257 nm mainly arise from MLCT or ligand-metal charge transfer transitions. Alkyl spacer does not play a crucial role on the main electron transitions. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011

Sol-gel synthesis of yellow-emitting La 4Ca(SiO 4) 3O:Ce 3+ phosphors for white-light emitting diodes

Ce 3+ doped La 4Ca(SiO 4) 3O phosphors with silicate oxyapatite structure were synthesized by the sol-gel process. The X-ray diffraction (XRD) patterns showed that a pure phase was formed when sintering temperature was higher than 1300°C. The optical properties of La 4Ca(SiO 4) 3O:Ce 3+ phosphors with varying sintering temperature and concentration were investigated by examining their excitation and emission spectroscopy. The phosphors exhibited a broad emission band centered at 550nm which could be attributed to the 5d-4f transition of Ce 3+ and a stronger excitation peak around 467nm as well as several shoulder bands, nicely matching with the widely applied blue LED chips. Higher emission intensity was observed when firing temperature above 1300°C, due to increasing crystallinity of the powders. When Ce 3+ concentration was equal to 5 at%, the sample exhibited the optimum excitation and emission efficiency. The results indicate that La 4Ca(SiO 4) 3O:Ce 3+ is a promising candidate in the application of blue chip excited white light emitting diodes (LEDs).

Low-n Rydberg Transitions of Liquid Ketones Studied by Attenuated Total Reflection Far-Ultraviolet Spectroscopy

Far-ultraviolet (FUV) spectra in the 8.55-6.20 eV (145-200 nm) region were measured for several kinds of ketones in the liquid phase to investigate low-n Rydberg transitions using a uniquely developed technique of attenuated total reflection (ATR) FUV spectrometry. Assignments of the transitions are attempted for absorptions in this region by comparing the spectra for the liquid phase with those for the gas phase and ab initio calculations at the equation-of-motion coupled cluster theory with single and double substitutions at the aug-cc-pVDZ level. The transition from a nonbonding electron (n) to the 3s Rydberg orbital was found at around 6.7 eV for all investigated liquid ketones. Another intense band also appeared in the higher-energy region (ca. 8.5 eV) for all the ketones. A significant shoulder was found at around 7.4 eV for branched ketones. This shoulder band near 7.4 eV was assigned to the n-3p Rydberg transition. Band broadening and higher energy shifts were observed in the spectra of the liquid phase ketones in comparison with those of the gas phase ketones.

Investigations of Low Temperature Phase Transitions in BiFeO3 Ceramic by Infrared Spectroscopy

In this paper, results of new infrared FIR-MIR measurements (wavenumber range of 4000–100 cm−1) in the range of the temperature 300 ÷ 8 K of the BiFeO3 ceramic are presented. Below 200 K only one symmetric band at ca. 800 cm−1 is visible. The full width at half maximum of this band decreases exponentially on cooling. The shape of the band at ca. 545 cm−1connected with A1 (TO) mode also changes between 60–40 K, this is in the vicinity of the phase transition at 50 K. Initially a broad band reveals its components as shoulder bands. Theirs FWHM decrease with cooling.

Direct Growth of Gold Nanorods on Gold and Indium Tin Oxide Surfaces: Spectral, Electrochemical, and Electrocatalytic Studies

The surfactant-assisted seed-mediated growth method was used for the formation of gold nanorods (GNRs) directly on gold (Au) and indium tin oxide (ITO) surfaces. Citrate-stabilized ∼2.6 nm spherical gold nanoparticles (AuNPs) were first self-assembled on ITO or Au surfaces modified with (3-mercaptopropyl)-trimethoxysilane (MPTS) sol−gel film and then immersed in a cationic surfactant growth solution to form GNRs. The growth of GNRs on the MPTS sol−gel film modified ITO surface was monitored by UV−visible spectroscopy. The ITO surface with the attached spherical AuNPs shows a surface plasmon resonance band at 550 nm. The intensity of this absorption band increases while increasing the immersion time of the AuNP-modified ITO surface into the growth solution, and after 5 h, an additional shoulder band around 680 nm was observed. The intensity of this shoulder band increases, and it was shifted to longer wavelength as the immersion time of the AuNP-modified ITO surface into the growth solution increases. After 20 h, a predominant wave at 720 nm was observed along with a band at 550 nm. Further immersion of the modified ITO surface into the growth solution did not change the absorption characteristics. The bands observed at 550 and 720 nm were characteristics of GNRs, corresponding to transverse and longitudinal waves, respectively. The AFM images showed the presence of GNRs on the surface of the MPTS sol−gel modified ITO surface with a typical length of ∼100−120 nm and a width of ∼20−22 nm in addition to a few spherical AuNPs, indicating that seeded spherical AuNPs were not completely involved in the GNRs’ formation. Finally, the electrocatalytic activity of the surface-grown GNRs on the MPTS sol−gel film modified Au electrode toward the oxidation of ascorbic acid (AA) was studied. Unlike a polycrystalline Au electrode, the surface-grown GNR-modified electrode shows two well-defined voltammetric peaks for AA at 0.01 and 0.35 V in alkaline, neutral, and acidic pHs. The cause for the observed two oxidation peaks for AA was due to the presence of both nanorods and spherical nanoparticles on the electrode surface. The presence of spherical AuNPs on the MPTS sol−gel film oxidized AA at more positive potential, whereas the GNRs oxidized AA at less positive potential. The observed 340 mV less positive potential shift in the oxidation of AA suggested that GNRs are better electrocatalysts for the oxidation of AA than the spherical AuNPs.

Luminescence of Ce3+ and Pr3+ doped Sr2Mg(BO3)2 under VUV–UV and X-ray excitation

Abstract This report presents the luminescence properties of Ce 3+ and Pr 3+ activated Sr 2 Mg(BO 3 ) 2 under VUV–UV and X-ray excitation. The five excitation bands of crystal field split 5d states are observed at about 46 729, 44 643, 41 667, 38 314 and 29 762 cm −1 (i.e. 214, 224, 240, 261 and 336 nm) for Ce 3+ in the host lattice. The doublet Ce 3+ 5d→4f emission bands were found at about 25 840 and 24 096 cm −1 (387 and 415 nm). The influence of doping concentration and temperature on the emission characteristics and the decay time of Ce 3+ in Sr 2 Mg(BO 3 ) 2 were investigated. For Pr 3+ doped samples, the lowest 5d excitation band was observed at about 42017 cm −1 (238 nm), a dominant band at around 35714 cm −1 (280 nm) and two shoulder bands were seen in the emission spectra. The excitation and emission spectra of Ce 3+ and Pr 3+ were compared and discussed. The X-ray excited luminescence studies show that the light yields are ∼3200±230 and ∼1400±100 photons/MeV of absorbed X-ray energy for the samples Sr 1.86 Ce 0.07 Na 0.07 Mg(BO 3 ) 2 and Sr 1.82 Pr 0.09 Na 0.09 Mg(BO 3 ) 2 at RT, respectively.

Structure of selected basic copper(II) sulphate minerals based upon spectroscopy – Implications for hydrogen bonding

The application of near-infrared and infrared spectroscopy has been used for identification and distinction of basic Cu-sulphates that include devilline, chalcoalumite and caledonite. Near-infrared spectra of copper sulphate minerals confirm copper in divalent state. Jahn–Teller effect is more significant in chalcoalumite where 2B 1g → 2B 2g transition band shows a larger splitting (490 cm −1) confirming more distorted octahedral coordination of Cu 2+ ion. One symmetrical band at 5145 cm −1 with shoulder band 5715 cm −1 result from the absorbed molecular water in the copper complexes are the combinations of OH vibrations of H 2O. One sharp band at around 3400 cm −1 in IR common to the three complexes is evidenced by Cu OH vibrations. The strong absorptions observed at 1685 and 1620 cm −1 for water bending modes in two species confirm strong hydrogen bonding in devilline and chalcoalumite. The multiple bands in ν 3 and ν 4(SO 4) 2− stretching regions are attributed to the reduction of symmetry to the sulphate ion from T d to C 2V. Chalcoalumite, the excellent IR absorber over the range 3800–500 cm −1 is treated as most efficient heat insulator among the Cu–sulphate complexes.

Visible and near-infrared luminescence of helical zinc(II)-lanthanide(III) trinuclear complexes having acyclic Bis(N2O2) oxime ligand

Luminescent properties of helical zinc(II)-lanthanide(III) complexes [LZn2Ln] (Ln = La3+, Ce3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Ho3+, Er3+, Tm3+, Yb3+, Lu3+), which are obtained by the reaction of acyclic bis(N2O2) tetraoxime ligand with zinc(II) and lanthanide(III) ions, were studied. The 1H NMR spectral study indicated that the complexes [LZn2Ln] adopt a helical conformation in solution, where two terminals are in an equivalent environment. In the absorption spectra, the π-π* transitions of ligand L4− were observed at around 330-340 nm associated with two shoulder bands between 370-450 nm. Upon excitation at 425 nm, [LZn2La] showed relatively intense ligand-centered emission at 540 nm (quantum yield, 0.052). The corresponding luminescence of the complexes of all other lanthanides [LZn2Ln] (Ln = Ce3+ -Lu3+) was much weaker. The complexes [LZn2Ln] (Ln = Sm3+, Eu3+, Tb3+, Dy3+) did not show detectable metal-centered emission, although these ions are potentially emissive in the visible region. On the other hand, [LZn2Nd] and [LZn2Yb] exhibited metal-centered emission due to f-f transition in the near infrared region in addition to the weak ligand-centered emission. Consequently, the ligand L4− can work as a sensitizer for Nd3+ and Yb3+ luminescence in the near infrared region.