Cations in a Molecular Funnel: Vibrational Spectroscopy of Isolated Cyclodextrin Complexes with Alkali Metals

The benchmark inclusion complexes formed by -cyclodextrin (CD) with alkali-metal cations are investigated under isolated conditions in the gas phase. The relative CD-M+ (M=Li+, Na+, K+, Cs+) binding affinities and the structure of the complexes are determined from a combination of mass spectrometry, infrared action spectroscopy and quantum chemical computations. Solvent-free laser desorption measurements reveal a trend of decreasing stability of the isolated complexes with increasing size of the cation guest. The experimental infrared spectra are qualitatively similar for the complexes with the four cations investigated, and are consistent with the binding of the cation within the primary face of the cyclodextrin, as predicted by the quantum computations (B3LYP/6-31+G*). The inclusion of the quantum-chemical cation disrupts the C6 symmetry of the free cyclodextrin to provide the optimum coordination of the cations with the -CH2OH groups in C1, C2 or C3 symmetry arrangements that are determined by the size of the cation

New records and detailed distribution and abundance of selected arthropod species collected between 1999 and 2011 in Azorean native forests

Background In this contribution we present detailed distribution and abundance data for arthropod species identified during the BALA - Biodiversity of Arthropods from the Laurisilva of the A zores (1999-2004) and BALA2 projects (2010-2011) from 18 native forest fragments in seven of the nine Azorean islands (all excluding Graciosa and Corvo islands, which have no native forest left). New information Of the total 286 species identified, 81% were captured between 1999 and 2000, a period during which only 39% of all the samples were collected. On average, arthropod richness for each island increased by 10% during the time frame of these projects. The classes Arachnida, Chilopoda and Diplopoda represent the most remarkable cases of new island records, with more than 30% of the records being novelties. This study stresses the need to expand the approaches applied in these projects to other habitats in the Azores, and more importantly to other less surveyed taxonomic groups (e.g. Diptera and Hymenoptera). These steps are fundamental for getting a more accurate assessment of biodiversity in the archipelago. © Borges P et al