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Two regioisomeric phenalenocarbazoles have been synthesized by direct reductive cyclization of 2′-Nitrophenyl-pyrene isomers respectively. Their photophysical properties and crystal structures as well as CV properties were investigated and compared with those of sulfur containing analogues. Although the fluorescence emission properties of 1N are very similar with those of 2N , the HOMO energy level of 1N is 0.16 eV higher than that of 2N indicating that 1N has better electron donating ability. [ABSTRACT FROM AUTHOR]

Infrared (IR) spectroscopy using a smart endurance single bounce diamond attenuated total reflection (ATR) cell has been used to study the changes in the spectra of the surfactant octadecyltrimethylammonium (ODTMA) bromide upon intercalation into a sodium montmorillonite. The wavenumbers of bands attributed to CH-stretching and CH-bending vibrations, in general, decrease as the concentration of the surfactant measured in terms of the cation exchange capacity (CEC) up to 1.0 CEC. After this point, the bands increase approaching a value the same as that of the surfactant. Significant changes occur in the HCH deformation modes of the methyl groups of the surfactant. These changes are attributed to the methyl groups locking into the siloxane (SiO) surface of the montmorillonite. Such a concept is supported by changes in the SiO-stretching bands of the montmorillonite siloxane surface. [Copyright &y& Elsevier]

Infrared spectroscopy has been used to characterise synthesised hydrotalcites of formula MgxZn6−xCr2(OH)16(CO3) · 4H2O and NixCo6−xCr2(OH)16(CO3) · 4H2O. The infrared spectra are conveniently subdivided into spectral features based (a) upon the carbonate anion (b) the hydroxyl units (c) water units. Three carbonate antisymmetric stretching vibrations are observed at around 1358, 1387 and 1482 cm−1. The 1482 cm−1 band is attributed to the CO stretching band of carbonate hydrogen bonded to water. Variation of the intensity ratio of the 1358 and 1387 cm−1 modes is linear and cation dependent. By using the water bending band profile at 1630 cm−1 four types of water are identified (a) water hydrogen bonded to the interlayer carbonate ion (b) water hydrogen bonded to the hydrotalcite hydroxyl surface (c) coordinated water and (d) interlamellar water. It is proposed that the water is highly structured in the hydrotalcite interlayer as it is hydrogen bonded to both the carbonate anion, adjacent water molecules and the hydroxyl surface. [Copyright &y& Elsevier]

FTIR and Infrared emission spectroscopy (IES) has been used to characterise the Uley (Australian) and Garfield nontronites. These clay minerals are characterised by a strong emission band at 3570 cm−1 attributed to the FeFeOH unit. Dehydroxylation is followed by the loss of intensity of this band as a function of temperature. Dehydroxylation is also followed by the loss of intensity of the FeFeOH deformation vibration at 843 cm−1. IES shows that the dehydroxylation occurs as a continuous process in comparison to DTA/TGA studies where the dehydroxylation occurs abruptly at 425 °C. Water in these high iron bearing smectites have been observed through the stretching mode at 3430 cm−1 and the bending mode at 1630 cm−1. Different types of water are identified in the nontronite structure by the analysis of the band profile in the 1590–1680 cm−1 region. Low frequency vibrations show that the Uley green nontronite is similar to the Garfield nontronite. The brown Uley nontronite is closer to the Hohen–Hagen nontronite. The Uley nontronites may, therefore, be used spectroscopically to replace other nontronites as a reference clay mineral. [ABSTRACT FROM AUTHOR]

The existence of life on planets such as Mars depend upon the presence of water. This water may not necessarily be as liquid or crystalline water but may be as interlayer water such as is found in smectitic clays. One group of smectites, relevant to the search for interplanetary life are those which have a high iron content, known as nontronites. Near-IR reflectance spectroscopy has been used to show the presence of water and hydroxyl units in these minerals. Three near-IR spectral regions are identified, (a) the high frequency region between 6400 and 7400 cm−1 attributed to the first overtone of the hydroxyl stretching mode; (b) the 4800–5400 cm−1 region attributed to water combination modes; and (c) the 4000–4800 cm−1 region attributed to the combination of the stretching and deformation modes of the FeFeOH units of nontronite. Two types of hydroxyl groups were identified using near-IR spectroscopy, hydroxyl units coordinated to the iron; and hydroxyl groups from water in the nontronite structure. The first hydroxyls are characterised by several bands, firstly in the 7055–7098 cm−1 region assigned to the first overtone of the AlFeOH stretching unit, secondly in the 6958–6878 cm−1 region attributed to the FeFeOH unit. The overtone of the hydroxyl stretching frequency of water was observed at around 6800 cm−1. These observations show that nontronites can be a source of water that may support life. [ABSTRACT FROM AUTHOR]

The Raman spectra of the minerals cerrusite (PbCO3), hydrocerrusite (Pb2(OH)2CO3), phosgenite (Pb2CO3Cl2) and laurionite (Pb(OH)Cl) have been used to qualitatively determine their presence. Laurionite and hydrocerrusite have characteristic hydroxyl stretching bands at 3506 and 3576 cm−1. Laurionite is also characterised by broad low intensity bands centred at 730 and 595 cm−1 attributed to hydroxyl deformation vibrations. The minerals cerrusite, hydrocerrusite and phosgenite have characteristic CO (ν1) symmetric stretching bands observed at 1061, 1054 and 1053 cm−1. Phosgenite displays complexity in the CO (ν3) antisymmetric stretching region with bands observed at 1384, 1327 and 1304 cm−1. Cerrusite shows bands at 1477, 1424, 1376 and 1360 cm−1. The hydrocerrusite Raman spectrum has bands at slightly different positions from cerrusite, with bands at 1479, 1420, 1378 and 1365 cm−1. The complexity of the ν3 region is also reflected in the ν2 and ν4 regions with the observation of multiple bands. Laurionite is characterised by two intense bands at 328 and 272 cm−1 attributed to PbO and PbCl stretching bands. Importantly, all four minerals are characterized by their Raman spectra, enabling the mineral identification in leachates and contaminants of environmental significance. [Copyright &y& Elsevier]