Nitrile-Functionalized Pyridinium, Pyrrolidinium, and Piperidinium Ionic Liquids

Two series of 1-alkylpyridinium and N-alkyl-N-methylpiperidinium ionic liquids fiinctionalized with a nitrile group at the end of the alkyl chain have been synthesized. Structural modifications include a change of the alkyl spacer length between the nitrile group and the heterocycle of the cationic core, as well as adding methyl or ethyl substituents on different positions of the pyridinium ring. The anions are the bromide and the bis(trifluoromethylsulfonyl)imide ion. All the bis(trifluoromethylsulfonyl)imide salts as well as the bromide salts with a long alkyl spacer were obtained as viscous liquids at room temperature, but some turned out to be supercooled liquids. In addition, pyrrolidinium and piperidinium ionic liquids with two nitrile functions attached to the heterocyclic core have been prepared. The crystal structures of seven pyridinium bis(trifluoromethylsulfonyl)imide salts are reported. Quantum chemical calculations have been performed on model cations and ion pairs with the bis(trifluoromethylsulfonyl)imide anion. A continuum model has been used to take solvation effects into account. These calculations show that the natural partial charge on the nitrogen atom of the nitrile group becomes more negative when the length of the alkyl spacer between the nitrile functional group and the heterocyclic core of the cation is increased. Methyl or methoxy substituents on the pyridinium ring slightly increase the negative charge on the nitrile nitrogen atom due to their electron-donating abilities. The position of the substituent (ortho, meta, or para) has only a very minor effect on the charge of the nitrogen atom. The N-15 NMR spectra of the bis(trifluoromethylsulfonyl)imide ionic liquids were recorded with the nitrogen-15 nucleus at its natural abundance. The chemical shift of the N-15 nucleus of the nitrile nitrogen atom could be correlated with the calculated negative partial charge on the nitrogen atom.

A three-position spectral line survey of Sagittarius B2 between 218 and 263 GHz. I. The observational data

We have surveyed the frequency band 218.30-263.55 GHz toward the core positions N and M and the quiescent cloud position NW in the Sgr B2 molecular cloud using the Swedish-ESO Submillimetre Telescope. In total 1730, 660, and 110 lines were detected in N, M, and NW, respectively, and 42 different molecular species were identified. The number of unidentified lines are 337, 51, and eight. Toward the N source, spectral line emission constitutes 22% of the total detected flux in the observed band, and complex organic molecules are the main contributors. Toward M, 14% of the broadband flux is caused by lines, and SO2 is here the dominant source of emission. NW is relatively poor in spectral lines and continuum. In this paper we present the spectra together with tables of suggested line identifications.

A STUDY OF CARBON-MONOXIDE AND NEUTRAL CARBON IN THE S106 MOLECULAR CORE

Maps are presented of J=2-1 and J=3-2 (CO)-O-18 emission from the molecular environment of the bipolar nebula S106, together with complementary observations of the P-3(1)-P-3(0), C I emission. Line splitting observed extensively over the E molecular cloud suggests that it is best explained as the expanding remnant of a thick toroid surrounding the optical lobes. The poor correlation between the observed molecular line emission and dust continuum emission in the E cloud is probably due to a large temperature gradient. Strong C I emission from the protostellar candidate S106 FIR suggests the nearby presence of a powerful source of far-UV radiation, whose energy supply is unlikely to arise from gravitational contraction of a protostar. It is probable that this source is the star S106 LR, which also heats S106 FIR. There is evidence, in both C I and (CO)-O-18, for a predominantly blueshifted outflow from S106 IR, best interpreted as a stellar wind-driven shock into the toroidal remnant. (CO)-O-18 and (CO)-C-13 appear to be depleted, relative to canonical values for their abundances, in S106 FIR, despite its high optical extinction, which should discourage selective photodissociation. Elsewhere in the cloud the C I line profiles show a resemblance to those of (CO)-O-18, with intensity equivalent to a few photodissociation regions (PDRs) along the line of sight.

DENSE GAS IN NEARBY GALAXIES .9. A SURVEY FOR HNC

Ten detections and five tentative detections of hydrogen isocyanide (HNC) J=1-0 emission are reported from a survey including sixteen galaxies. Full maps are presented for the nuclear regions of NGC 253 and IC 342, partial maps for Maffei 2, M 82, and M 83. Toward IC 342, the HNC and HCO+ distributions differ from those observed in 12CO, 13CO, HCN, CS, and NH3. This is likely a consequence of the density structure. Relative HNC abundances are with 10(-10)-10(-9) much smaller than those measured in nearby dark clouds and appear to be slightly smaller than those in regions of massive star formation of the Galactic disk. This is consistent with the presence of dense warm gas or a frequent occurrence of shocks in the nuclear regions of the galaxies observed. As in prominent Galactic star forming regions, 3 mm HNC line emission tends to be weaker than the corresponding emission from HCN and HCO+. Toward Arp 220, however, the 3 mm HNC/HCN line intensity ratio is > 1. HNC/HCO+, HNC/CO, and HNC to 20 cm radio continuum luminosity ratios are also particularly large. A possible interpretation is the presence of cool quiescent gas outside the central region which contains the starburst. In the other ultraluminous galaxy observed, NGC 6240, X(HNC) 10 smaller than in Arp 220, demonstrating that the molecular composition in ultraluminous galaxies is far from being uniform.

Body size differs in workers produced across time and is associated with variation in the quantity and composition of larval food in Nannotrigona perilampoides (Hymenoptera, Meliponini)

Although variation in body size has been recently reported in stingless bees (Meliponini), empirical evidence evaluating possible factors related to such variation is lacking, and thus it is not clear if it may have an adaptive significance. We evaluated if variation in the body size and weight of workers of stingless bees fluctuates across a seasonal pattern and if this could be related to characteristics of the food consumed during the larval stage. The weight of larval provisions, their protein, and sugar content were evaluated in four colonies of Nannotrigona perilampoides every 2 months across 1 year. Worker-destined larvae from the same combs were allowed to develop and were sampled as callow workers to determine their weight and size using morphometric data. The weight and size of workers were highly correlated and varied across the seasons in established colonies, suggesting that size variation cycles across the year in stingless bees. An increase in the protein content and, to a lesser degree, the quantity of larval food were positively linked to variation in body weight and size; food with richer protein content resulted in larger and heavier workers. This study provides the first evidence of an effect of the quantity and composition of larval food on the size of workers in stingless bees. Although body weight and size of workers differed across seasons, they were not readily noticeable as changes seem to occur as a continuum across the year. Since size polymorphism was of a larger magnitude across time but not within age cohorts and as it was highly determined by food resources, it may not be an adaptive feature in stingless bees. However, more studies are needed to determine the role of the cyclical change in worker body size on colony performance and thus its adaptive significance in stingless bees.