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▪ Abstract Recent progress on the use of near-field scanning optical microscopy (NSOM) to characterize organic thin film materials is extensively reviewed. NSOM is leading to important new information on the morphology and spatially resolved optical properties of a variety of materials, complementing more widely available methods for thin film analysis. Materials described in this review include polymer thin films, molecular aggregates, molecular crystals, molecular semiconductor heterojunctions, biological materials, and molecular mono-, bi-, and multi-layer films.

Raman spectra of Mn2(CO)10 and Re2(CO)10 have been studied to 27 and 98 kbar respectively, and the infrared (IR) spectrum of Re2(CO)10 to 30 kbar at ambient temperature. Both materials undergo a first-order structural phase transition at high pressure (Mn at approximately 8 kbar, Re at approximately 5 kbar) which is accompanied by dramatic changes in all regions of their vibrational spectra. These data are interpreted in terms of a change of molecular geometry from D4d to D4h. In the new high-pressure phases the M to carbonyl backbonding is increased significantly for the axial but not the equatorial carbonyls. The molecular torsion is implicated in the phase change but is not thought to drive it.

The so-called 'valence transition' in EuPd2Si2 has been observed using energy-dispersive synchrotron X-ray powder diffraction at elevated pressures and is centred at 8 kbar. The estimated increase in valence at the transition is 0.2, and is associated with crossover of 4f and 6d/s bands.

Using synchrotron energy-dispersive X-ray powder diffraction (EDXRPD) the authors have shown that K2SnBr6 transforms at pressures of 14 kbar and above from the parent monoclinic cell to a cubic structure of symmetry Fm3m, which is stable to 120 kbar. A different phase appears to exist above 120 kbar.

The structural behaviour of ammonium metavanadate, NH4VO3, under high pressures has been studied to 65 kbar using energy-dispersive synchrotron X-ray powder diffraction, and to 106 kbar by FTIR methods, in a diamond anvil cell. A reversible crystalline-to-disordered phase transition was found at 49 kbar. The transition is thought to be due to relative slipping of the vanadate chains parallel to their axes, the product being disordered, possibly amorphous, rather than crystalline because the process is hindered and the solid prevented from attaining periodicity by hydrogen bonding to ammonium ions.

That part of the field of single-crystal vibrational spectroscopy which is devoted to acquisition of well-proven assignments in terms of symmetry species is first placed within the wider context of solid state spectroscopy as a whole. Theoretical and practical factors which limit the size of crystal with which meaningful polarisation data can be obtained are then considered. Finally, brief summaries are given of selected areas of recent significant activity: chain and layer structures, silicates, and complexes with donor ligands.

A summary account is given of the phase transitions found at high pressure for several inorganic carbonyl and cyanide complexes: M(CO)6, (M = Cr, Mo, W); Re(CO)5Br; M2(CO)10, (M = Mn, Re) and MnRe(CO)10; Hg(CN)2; K2M(CN)4, (M = Zn, Cd, Hg); and K3Cu(CN)4. The structures of some of the phases have been deduced using group theoretical methods.

IR and Raman spectra of MCl2(meso-2,3-diaminobutane), (M = Pd, Pt), have been recorded down to liquid nitrogen temperature or lower. It is shown that correlation coupling occurs between closely spaced hydrogen-bonded pairs of molecules, which form a “super molecule,” but not between all eight molecules in the unit cell. The lattice mode region is also understood in outline on the basis of motions of the “super molecules” Methyl torsional modes appear to be near 140 cm−1.

Ultrahigh temperature sterilized canned puddings occasionally exhibit spoilage in the form of a dramatic loss of viscosity or thinning. Studies on a concentrated fraction of spoiled pudding indicate that thinning was due to a heat-resistant amylase. The concentrate was obtained by centrifugation and ultrafiltration of the thinned pudding. Ultrafiltration characteristics of the active agent indicate a molecular weight of 1–30 × 104 daltons. The agent attacked starch with a decrease in iodine-binding capability and an increase in reducing units. Treatment of the concentrate with proteolytic enzymes decreased enzymatic activity by 50%; treatment with sodium ethylene diaminetetraacetate decreased activity by 80%. The levels of starch and pH of the spoiled puddings were suitable for action of the amylase, and the enzyme was quite active at normal and elevated room temperatures.

The α-amylase of the thermophile Bacillus stearothermophilus 1518 was used as a model enzyme to examine the heat resistance of a bacterial amylase at ultrahigh temperature in a starch-based pudding. When heated in the laboratory pudding at 143°C for the equivalent of 22.2 set, approximately 26% of the initial amylolytic activity was retained. The presence or absence of individual ingredient groups (starch, caseinate-nonfat dry milk, oilemulsifiers, salts, or sucrose) of the pudding had no significant effect on amylase heat resistance. A combination of any two of the starch, caseinate-nonfat dry milk, or oil-emulsifier ingredients were found to be important for thermostability. The amylase of the mesophile Xanthomonas campestris 13957–2 exhibited similar thermal inactivation characteristics.

Potassium nitrate (KNO3) has seven polymorphs in the pressure range 0-4.0 GPa. The authors have studied it at room temperature as a function of pressure up to 9.3 GPa and have confirmed the structure of phase IV previously refined by neutron diffraction at 0.36 GPa. The compressibility measured in the range 0.3-9.3 GPa is found to be anisotropic with the axial compression ratios a:b:c=1.0:0.64:0.50. The relative merits of X-rays and neutrons for high-pressure studies are discussed.

Phase transitions have been observed in mercury (II) cyanide near 2.5, 89, 19 and 60 kbar. The I/II transition appears to be of second order with the structure of phase II closely related to that of the parent molecular type. Using Landau theory, three possible structures have been identified for the new phase II, of which S24 is marginally better in accord with the evidence. A major reconstruction of the lattice occurs at the II/III transition; the coordination number of mercury appears to increase to four, and the structure becomes covalently bonded, rather than molecular. Phase IV has a spectrum consistent with it having the cubic anti-cuprite structure adopted at STP by Zn(CN)2 and Cd(CN)2. Above 60 kbar, brown polymeric Hg(CN)2V is formed irreversibly. It has a single IR absorption

Clostridium perfringens spores were injured by ultrahigh-temperature treatment at 105 C for 5 min. Injury was manifested as an increased sensitivity to polymyxin and neomycin. Since many of the survivors could not germinate normally the ultrahigh-temperature-treated spores were sensitized to and germinated by lysozyme. Polymyxin reportedly acts upon the cell membrane. Neomycin may inhibit protein synthesis and has surface-active properties. Injured spores were increasingly sensitive to known surface-active agents, sodium lauryl sulfate, sodium deoxycholate, and Roccal, a quaternary ammonium compound. Injured spores sensitive to polymyxin and neomycin also were osmotically fragile and died during outgrowth in a liquid medium unless the medium was supplemented with 20% sucrose, 10% dextran, or 10% polyvinylpyrrolidone. The results suggested that a spore structure destined to become cell membrane or cell wall was the site of injury. Repair of injury during outgrowth in the presence of protein, deoxyribonucleic acid, ribonucleic acid and cell wall synthesis inhibitors was consistent with this hypothesis.

The heat resistant lipase of Pseudomonas spp. MC50 hydrolyzed coconut oil, corn oil, butter oil and olive oil. Lipase activity was maximum at 1% corn oil. The effects of pH and temperature on lipase activity varied with the substrate. The pH optima were in the range pH 8–9; the temperature optima were in the range 35–40°C. Of several emulsifiers tested, four supported significant lipase actiivity, and three supported no lipase activity and may have inhibited the lipase. Emulsifier concentration influenced lipase activity. All stabilizers tested supported lipase activity; above 0.36% stabilizer concentration had no effect.

Pseudomonas spp. MC50 produced an extra-cellular lipase that was extremely heat resistant at 100–150°C when heated in water or emulsions. The D-values ranged from 40 min at 100°C to 84 sec at 150°C. The zD-vallue was 36°C. When heated in water, the lipase exhibited greatest survival at pH 8.5. Below pH 6.5, survival was less than 10% of that at pH 8.5. Survival of lipase heated in emulsions was affected somewhat by the type of oil, corn oil concentration, and type of emulsifier. Type of stabilizer or stabilizer concentration had little effect on lipase survival. Lipase treated with ethylenediaminetetraacetate (EDTA) was fully heat resistant in water; survival declined when lipase was heated in CaCl2 solutions of 3–120 mM.

Raman spectra of NaNO2 have been studied as a function of hydrostatic pressure to 40 kbar at 295 and 348 K. Slight changes in slope of mode frequency versus pressure plots support the view that a structural anomaly exists at 9 ± 1 kbar. The absence of qualitative changes in the Raman spectra allow the space group of NaNO2 IV to be specified as one of P1, P2, B2, Pm or Bm. The Raman spectrum of NaNO3 has been studied to 87 kbar. The changes observed are fully consistent with a second-order transition to a phase with symmetry C63v, as indicated by previous X-ray work, although the transition is sluggish.

The effect of pressure at low temperature (166.8K) upon the R1 and R2 lines of ruby has been investigated for the first time to establish a calibration for use in high-pressure/low-temperature work. A reinvestigation of the behaviour of R1 and R2 at ambient temperatures and at pressures up to ca 70 kbar supports previous work on the calibration under hydrostatic conditions but shows that in a 4:1 methanol:ethanol mixture conditions become nonhydrostatic at lower pressures (ca 50 kbar) than claimed (ca 100 kbar). The importance of monitoring both R1 and R2 is emphasised as their relative shifts are sensitive indicators of the presence, and approximate magnitude, of non-hydrostatic stress components. It is shown that although changes in half-bandwidths are also associated with development of shear stress, their use in estimating gradients is extremely hazardous and can indicate values greatly in excess of the known shear strength of the material.

Raman spectra have been obtained for HgCl2 to 145 kbar and HgBr2 to 100 kbar and phonon pressure dependencies established. The phase transition in HgCl2 said to be at 6.5 kbar, on NQR evidence, has been located at 2.2 kbar. A new first-order phase change has been found in HgCl2 at 79.0 kbar. Also in HgCl2, there are two bands that pressure scan differentially such that one overtakes the other, but they do not appear to be in resonance. Improved values for the phase transitions in HgBr2 are 4.0, 26.0 and 41.0 kbar. It is suggested that there are no structural equivalences between the two series of four polymorphs based upon the chloride and bromide respectively.

The far-infrared spectra of platinum(IV) complexes of the types cis- and trans-[PtX4L2](X = Cl, Br, or I; L = donor ligand) are assigned and discussed. For the trans complexes the halogen-sensitive modes occur near those of the related [PtX4]2– species whilst the ν(Pt–X) pattern for the cis complexes covers a wide range which includes that of ν(Pt–X) in bridging situations in platinum(II) compounds. Assignments are given for ν(Pt–P), ν(Pt–As), ν(Pt–S), and for the associated bending modes.

Raman and far-i.r. spectra are reported and assigned for the solid complexes Cr(CO)3(π-arene)(arene = benzene, aniline, toluene, methyl benzoate, anisole, and hexamethylbenzene) and M(CO)3(π-mesitylene)(M = Cr, Mo, or W). For the benzene complex, discussion is based upon the factor group, but in the other cases the molecular point-symmetry proves to be an adequate approximation. C3v local symmetry is an inadequate approximation when discussing the skeletal modes of complexes of monsubstituted arenes.

Exposure of Bacillus subtilis A spores to 115 to 125 C for several seconds activated a low-temperature germination system that remained dormant after a heat treatment that activated the normal l -alanine- and glucose-stimulated germination systems. The low-temperature germination system was characterized by an optimum temperature lower than that of the l -alanine or glucose germination systems (30 C versus 45 C), germination in the absence of exogenous germination stimulants, and the capacity for heat-induced deactivation and subsequent reactivation. The rates of activation at 115 to 125 C were exponential and were not influenced by a previous heat treatment that activated the l -alanine- or glucose-stimulated germination systems. Although activation of the low-temperature germination system was accompanied by suppression of l -alanine-stimulated germination, it did not appear to be a modification of the l -alanine germination system.

Raman and i.r. spectra of the title compounds are reported and assigned for both solids and solutions. ν(C–H) modes show correlationsplitting, but the remainder of the internal modes of the π-allyl ligands can be discussed in terms of Cs local symmetry. ν(C–C–C) modes of the allyl skeleton are placed ca. 1383 and 1020 cm.–1 in the parent complex.

The O—H stretching frequency for methanol in the system methanol + dichloromethane + tetra-alkylammonium perchlorate is almost equal to that for a band which appears when perchlorate salts are dissolved only in methanol. The band is therefore assigned to methanol molecules hydrogen-bonded to perchlorate anions. A band which appears in the spectrum of HOD in H2O when perchlorates are added is, by analogy, similarly assigned. Other arguments against a previous theory that, for aqueous solutions, this band is due to free OD groups, are advanced. The influence of the cation upon the band for solvent molecules not associated with perchlorate ions is discussed.

The far-infrared spectra (70–400 cm.–1) of 36 thiourea and ethylenethiourea (imidazolidine-2-thione) complexes, embracing several different stereochemical types, are assigned and discussed. Metal–sulphur stretching frequencies, v(M–S), lie in the range 298–205 cm.–1 for the transition-metal complexes, and vary with co-ordination number and electron configuration in the manner now familiar from the behaviour of metal–hylogen stretching frequencies, v(M–X). For Group metals v(M–S) has been found as low as 170 cm.–1. The similarity between the spectra of thiourea complexes and those of thiocyanates has led to an assignment of the published data for thiocyanates. Some interesting variations in halogen-sensitive vibrations have been encountered.

I.r. spectra (70–4000 cm.–1) of nickel complexes of the type [Ni(S2C2R2)2]n–(R = H, CF3, or CN) and of [M(S2C2(CN)2)2]n–(M = Co, Cu, Zn, Pd, or Pt) are discussed. Vibrations containing a large (ν(M–S) contribution are found in the range 465–295 cm.–1. Frequency and intensity variations are consistent with the molecular orbital description of the bonding.For dithiophosphate complexes of three types of stereochemistry ν(M–S) is assigned in the region 330–220 cm.–1; the variation is mainly due to the differing masses of the metal.These results, together with other published work, lead to correlations for ν(M–S) for various ligands in the range 504–205 cm.–1.

Raman single-crystal spectra are reported for eight hydrates and deuteriates [MCl5(H2O)]2–(M = In or Fe). Many fewer lattice modes were found than predicted, but for the anion internal modes factor-group predictions accord well with observation. A complete assignment in terms of anion C4v symmetry is deduced. Deuteriation enabled identification of all skeletal modes associated with oxygen-atom motions. The most unusual feature of the assignments is that π(MCl4) modes come above δ(MCl4) modes. Comparison with single-crystal assignments for [InCl5]2– show that the largest change is in the A1π(InCl4) mode which is raised upon aquation of the complex.

The far-infrared spectra of some halogenocuprates of the types [CuX4]2–(planar and tetrahedral), [Cu2X6]2–, CsCuX3, and M2ICuCl4,2H2O have been studied. Complexes of the type CuX2L2(X = Cl or Br; L = donor ligand) are also considered. v(Cu–Cl) lies in the range 368—222 cm.–1 and v(Cu–Br) between 278 and 168 cm.–1. The spectra admit of a consistent interpretation without the need to postulate the presence of v(Cu–X) modes in the normal region due to stretching of copper–halogen “long” bonds. Bridging v(Cu–X) frequencies have been assigned but the range is severely overlapped by that of terminal v(Cu–X).

Clostridium perfringens spores (three strains) were normally resistant to germination by lysozyme. In the absence of disulfide bond-breaking reagents, tetrasodium ethylenediaminetetraacetate rapidly sensitized the spores to lysozyme.

The ν(CO) spectra of Mo(CO)4 bipy (bipy = 2,2′-bipyridyl), cis-[W(CO)2{o-C6H4(PEt2)2}2],Cr(CO)3(π-mesitylene), and Cr(CO)3(π-C6H5·CO2Me) are examined in solution in n-hexane–chloroform or –nitrobenzene mixtures; the ν(NO) spectrum of Fe(NO)(S2CNMe2)2 is studied in benzene–nitromethane mixtures. Structure observed on the ν(CO) bands is discussed in terms of formation of solvent–solute complexes.

Raman and i.r. spectra are reported and assigned for X2Sn[Co(CO)4]2,X2Sn[Fe(CO)2(π-C5H5)]2(X = Cl, Br, and I), and M-SnCl3, (M = Mo(CO)3(π-C5H5); Rh(NBD)2; Ir(COD)2), and for a number of related compounds. Metal–metal stretching frequencies are in the range 165–235 cm.–1 and are intense in the Raman spectra.

Spectroscopic Properties of Inorganic and Organometallic Compounds provides a unique source of information on an important area of chemistry. Divided into sections mainly according to the particular spectroscopic technique used, coverage in each volume includes: NMR (with reference to stereochemistry, dynamic systems, paramagnetic complexes, solid state NMR and Groups 13-18); nuclear quadrupole resonance spectroscopy; vibrational spectroscopy of main group and transition element compounds and coordinated ligands; and electron diffraction. Reflecting the growing volume of published work in this field, researchers will find this Specialist Periodical Report an invaluable source of information on current methods and applications. Specialist Periodical Reports provide systematic and detailed review coverage in major areas of chemical research. Compiled by teams of leading experts in their specialist fields, this series is designed to help the chemistry community keep current with the latest developments in their field. Each volume in the series is published either annually or biennially and is a superb reference point for researchers. www.rsc.org/spr

Spores of Clostridium perfringens NCTC 8798 became increasingly sensitive to inhibition by sodium chloride, sodium nitrite and a mixture of polymyxin and neomycin when heated at 70–100°C. That the increased sensitivity to each agent was caused by the same cellular damage was suggested by: (1) the temperature coefficients for induction of cellular damage leading to increased sensitivity to all three agents were the same; (2) in the absence of the agents, the spores regained resistance to all three at about the same time and in each case in the presence of cell wall-, protein- and DNA-synthesis inhibitors; (3) combinations of the agents were generally no more inhibitory to the heated spores than were the individual agents.