Evaluation of a single-monochromator diode array spectroradiometer for sunbed UV-radiation measurements

The suitability of a new technology single-monochromator diode array spectroradiometer for UV-radiation safety measurements, in particular for sunbed measurements, was evaluated. The linearity, cosine response, temperature response, wavelength scale, stray-light and slit function of the spectroradiometer were determined and their effects on the measurement accuracy evaluated. The main error sources were stray-light and nonideal cosine response, for which correction methods are presented. Without correction, the stray-light may reduce the accuracy of the measurement excessively, particularly in the UV-B range. The expanded uncertainty of the corrected UV measurements is estimated to be 14%, which is confirmed with the comparative measurements carried out with a well-characterized double-monochromator spectroradiometer. The measurement accuracy is sufficient for sunbed measurements, provided that all corrections described above have been done and the user of the instrument has a good understanding of the instrument's operating principles and potential error sources. If these requirements are met, the tested spectroradiometer improves and facilitates market surveillance field measurements of sunbeds.     

Conformational analysis 29: Preparation and1H and13C NMR,FTIR, MS,and crystallographic conformational and configurational study of 3-Oxo-1,3-oxathiane and its monomethyl derivatives

3-Oxo-1,3-oxathiane (1) and its monomethyl derivatives were prepared by oxidation of the corresponding 1,3-oxathianes. The structural analysis was carried out by¹H and¹³C NMR, FTIR, and mass spectrometry. At 298 K compound1 was a 1 1 (at 173 K a 3 1) mixture of the SO(ax) and SO(eq) chair forms. The major oxidation products of methyl 1,3-oxathianes attained exclusively the SO(ax), Me(eq) chair forms except that of the 5-methyl derivative, which consisted of 7% of the SO(eq), Me(ax) chair conformation in CDCl₃ solution. The minor products of oxidation existed in anancomeric SO(eq), Me(eq) chair conformations. The oxidation of 2-methyl- 1,3-oxathiane, however, led to 3,3-dioxo derivative (6) in addition to thetrans [SO(eq)] monoxide. The crystal structures of6 andtrans-3-oxo-5-methyl-1,3-oxathiane were solved by X-ray diffractometry.     

Quantification of antimony depth profiles in Sb-doped tin dioxide thin films

Sb-doped SnO(2) thin films, deposited by atomic layer epitaxy (ALE) for gas sensor applications, have been characterized by secondary ion mass spectrometry (SIMS). Quantification of the depth profile data has been carried out by preparing a series of ion implanted standards. Average concentrations determined by SIMS have been compared with Sb/Sn ratios obtained by X-ray fluorescence (XRF) spectrometry and proton induced X-ray emission (PIXE) spectrometry and have been found to be in good agreement. However, a detection limit of 5x10(18) at cm(-3) could only be obtained because of mass interferences. SIMS data show that the ALE technique can be used to produce a controllable growth and doping of thin films.     

Synthesis and coordinating ability of an anionic cobaltabisdicarbollide ligand geometrically analogous to BINAP

The anionic chelating ligand [1,1'-(PPh2)2-3,3'-Co(1,2-C2B9H10)2]- has been synthesized from [3,3'-Co(1,2-C2B9H11)2]- in very good yield in a one-pot process with an easy work-up procedure. The coordinating ability of this ligand has been studied with Group 11 metal ions (Ag, Au) and with transition-metal ions (Pd, Rh). The two dicarbollide halves of the [1,1'-(PPh2)2-3,3'-Co(1,2-C2B9H10)2]- ligand can swing about one axis in a manner analogous to the constituent parts of BINAP and ferrocenyl phosphine derivatives. All these ligands function as hinges, with the most important property in relation to the coordination requirements of the metal being the PP distance. [1,1'-(PPh2)2-3,3'-Co(1,2-C2B9H10)2]-, BINAP, ferrocenyl phosphine derivatives, and other hinge ligands present a range of different PP separations, and consequently different coordination spheres and dispositions around metal cations. To account for these differences, the equation Dphi2 = D02 + 4 R2cos2(90-phi/2) has been developed. It relates the PP distance (Dphi) in a complex with the minimum PP distance (D0) that is characteristic of the hinge-type ligand.     

Formation of bridging alkene and conjugated dialkenes exclusively generated from alkynes on the [3,3'-Co(1,2-C2B9H11)2]- platform. The unique hydroboration role of [3,3'-Co(1,2-C2B9H11)2]-

The unprecedented metal-mediated transformation of an alkyne into a B,B' bridging alkene is reported. Also, the unprecedented synthesis of a conjugated dialkene derivative of [3,3'-Co(1,2-C2B9H11)2]- generated only from an alkyne, contrary to the usual case where an alkyne and an alkene are needed, is described. This has been possible through the singular capacity of a B-H to produce hydroboration.     

X-ray crystal structures of [XF(6)][Sb(2)F(11)] (X = Cl, Br, I); (35,37)Cl, (79,81)Br, and (127)I NMR studies and electronic structure calculations of the XF(6)(+) cations

The single-crystal X-ray structures of [XF(6)][Sb(2)F(11)] (X = Cl, Br, I) have been determined and represent the first detailed crystallographic study of salts containing the XF(6)(+) cations. The three salts are isomorphous and crystallize in the monoclinic space group P2(1)/n with Z = 4: [ClF(6)][Sb(2)F(11)], a = 11.824(2) A, b = 8.434(2) A, c = 12.088(2) A, beta = 97.783(6) degrees , V = 1194.3(4) A(3), R(1) = 0.0488 at -130 degrees C; [BrF(6)][Sb(2)F(11)], a = 11.931(2) A, b = 8.492(2) A, c = 12.103(2) A, beta = 97.558(4) degrees , V = 1215.5(4) A(3), R(1) = 0.0707 at -130 degrees C; [IF(6)][Sb(2)F(11)], a = 11.844(1) A, b = 8.617(1) A, c = 11.979(2) A, beta = 98.915(2) degrees , V = 1207.8(3) A(3), R(1) = 0.0219 at -173 degrees C. The crystal structure of [IF(6)][Sb(2)F(11)] was also determined at -100 degrees C and was found to crystallize in the monoclinic space group P2(1)/m with Z = 4, a = 11.885(1) A, b = 8.626(1) A, c = 12.000(1) A, beta = 98.44(1), V = 1216.9(2) A(3), R(1) = 0.0635. The XF(6)(+) cations have octahedral geometries with average Cl-F, Br-F, and I-F bond lengths of 1.550(4), 1.666(11) and 1.779(6) [-173 degrees C]/1.774(8) [-100 degrees C] A, respectively. The chemical shifts of the central quadrupolar nuclei, (35,37)Cl, (79,81)Br, and (127)I, were determined for [ClF(6)][AsF(6)] (814 ppm), [BrF(6)][AsF(6)] (2080 ppm), and [IF(6)][Sb(3)F(16)] (3381 ppm) in anhydrous HF solution at 27 degrees C, and spin-inversion-recovery experiments were used to determine the T(1)-relaxation times of (35)Cl (1.32(3) s), (37)Cl (2.58(6) s), (79)Br (24.6(4) ms), (81)Br (35.4(5) ms), and (127)I (6.53(1) ms). Trends among the central halogen chemical shifts and T(1)-relaxation times of XF(6)(+), XO(4)(-), and X(-) are discussed. The isotropic (1)J-coupling constants and reduced coupling constants for the XF(6)(+) cations and isoelectronic hexafluoro species of rows 3-6 are empirically assessed in terms of the relative contributions of the Fermi-contact, spin-dipolar, and spin-orbit mechanisms. Electronic structure calculations using Hartree-Fock, MP2, and local density functional methods were used to determine the energy-minimized gas-phase geometries, atomic charges, and Mayer bond orders of the XF(6)(+) cations. The calculated vibrational frequencies are in accord with the previously published assignments and experimental vibrational frequencies of the XF(6)(+) cations. Bonding trends within the XF(6)(+) cation series have been discussed in terms of natural bond orbital (NBO) analyses, the ligand close-packed (LCP) model, and the electron localization function (ELF).     

Synthesis and stereochemical studies of 1- and 2-phenyl-substituted 1,3-oxazino[4,3-a]isoquinoline derivatives

Starting from the 1′- or 2′-phenyl-substituted 1-(2′-hydroxyethyl)-6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline diastereomers 3 and 6, 4-unsubstituted and 4-(p-nitrophenyl)- and 4-oxo-substituted 1-phenyl- and 2-phenyl-9,10-dimethoxy-2H,4H-1,6,7,11b-tetrahydro-1,3-oxazino[4,3-a]isoquinolines (7-12) were prepared. The relative configurations and the predominant conformations of the products were determined by NMR spectroscopy, by quantum chemical calculations and, for (2R^∗,4S^∗,11bR^∗)-9,10-dimethoxy-4-(p-nitrophenyl)-2-phenyl-2H,4H-1,6,7,11b-tetrahydro-1,3-oxazino[4,3-a]isoquinoline (11), by X-ray diffraction.     

Computational studies of the cationic aluminium(chloro) hydroxides by quantum chemical ab initio methods

Cationic aluminium(chloro) hydroxide complexes with two to four aluminium atoms were studied using quantum chemical methods. Complexes were studied in both gas and liquid phase. The liquid environment was modeled by using a conductor-like screening model (COSMO). COSMO calculations were carried out as a single point calculation at the optimized gas phase structures. Water (epsilon = 78.54) was used as the solvent. The minimum energy structures obtained from the gas phase studies were mostly compact cyclic structures. Aluminium preferred to be five-coordinated in oxygen rich clusters. Core oxygen preferred three-fold coordination but in the largest clusters the four-coordinated oxygen was observed. Water reacted dissociatively with hydrogen poor clusters. The COSMO calculations showed that the optimal structures of cationic aluminium(chloro) hydroxides tend to be more open in the liquid than in the gas phase.     

Diferratricarbaboranes of the subcloso-[(eta5-C5H5)2Fe2C3B8H11] type, the first representatives of the 13-vertex dimetallatricarbaborane series

Treatment of the [2-Cp-9-tBuNH-closo-2,1,7,9-FeC(3)B(8)H(10)] (1) ferratricarbollide (Cp = eta(5)-C(5)H(5) (-)) with Na(+) C(10)H(8) (-) in 1,2-dimethoxyethane (DME) at room temperature produced an air-sensitive transient anion with a tentatively identified nido-[tBuNH-CpFeC(3)B(8)H(10)](2-) constitution. In-situ reaction of this low-stability ion with [CpFe(CO)(2)I] or [CpFe(CO)(2)](2) generated three violet diferratricarbaboranes identified as paramagnetic subcloso complexes [4,5-Cp(2-)-4,5,1,6,7-Fe(2)C(3)B(8)H(11)] (2; yield 2 %), [4,5-Cp(2-)-4,5,1,7,12-Fe(2)C(3)B(8)H(11)] (3; yield 2 %), and [7-tBuNH-4,5-Cp(2-)-4,5,1,7,12-Fe(2)C(3)B(8)H(10)] (4; yield 14 %). These first representatives of the 13-vertex dimetallatricarbaborane family were characterized by EPR and IR spectroscopy, and mass spectrometry, and their structures were determined by X-ray diffraction analysis.