Influence of the guests, the type and degree of substitution on inclusion complex formation of substituted beta-cyclodextrins

The stability of inclusion complexes (i.e. the measure of molecular recognition between a guest and (beta-cyclodextrin, CD) is highly influenced by the fit of the guest into the cavity of the host and by secondary bonds among the functional groups getting in close connection. The guests themselves influence these interactions by their sizes, shapes and functional groups. On the other hand, both the size of the cavity and the reactivity of beta-CDs are altered when the hydroxy groups are substituted. As best models, the interactions among hydroxypropylated CDs of different average degree (and pattern) of substitution (DS) and phenolphthalein (as a model for 'large' guests) or p-nitrophenol/p-nitrophenolate (p-NP/p-NPate) couple (as for 'small' ones) have been studied. The formation constants of phenolphthalein-hydroxypropyl-beta-CD (HP-CD) complexes are continuously decreasing, while those of p-NP and p-NPate ones show a maximum with increasing DS. Similarly, the pattern of substitution has a significant effect on the quality of the interaction, too. The change of the DS on O(6) position alters the type of the interactions most, and a series of different findings prove that this change is the basis in the chiral selectivity of different CD derivatives, too. The ratio of the average DS on primary and secondary hydroxy rims [R(DS)=DS(6)/DS(2,3)] is recommended as the simplest possibility for characterizing the substitution pattern.     

Nanoparticle Polydispersity Can Strongly Affect In Vitro Dose

When nanomaterials meet the biological world, the cellular interaction of nanoparticles is routinely assessed in in vitro systems. Establishing dose–response relationships requires that the dose of nanoparticles delivered to the cell is accurate and precise. Nanoparticles as such or coated with high molecular‐weight compounds are rarely uniform and the influence of heterogeneity, including polydispersity both in size and mass density, on the delivered dose is never studied before. Furthermore, a probabilistic term describing particle adherence to cells is introduced and the importance is discussed. By tracing the movement of discrete particles via modeling, it is found that the influence of heterogeneity cannot be neglected when the average particle size promotes settling over diffusion. However, the influence of polydispersity on the delivered cellular dose is less critical for particulate systems whose mean size promotes diffusion. The influence of a non‐instantaneous particle association to the cell is negligible for particles whose motion is dominated by settling, but it is relevant for small particles whose motion is governed by diffusion.     

A Convenient Procedure for the Reduction of Sulfones to Sulfoxides

Although there have been a relatively large number of publications recently dealing with the reduction of sulfoxides fo sulfides^1,2 there are still very few general procedures for the reduction of sulfones to sulfides and none at all, as far as we are aware, for the reduction of sulfones to sulfoxides. In his paper dealing with the use of diisobutylaluminum hydride (DIBAL-H) for the reduction of sulfones to sulfides, for example, Gardner³ points out the inadequacies of the more readily available lithium aluminum hydride for this reduction. We have developed a two part procedure for reducing sulfones 1 to sulfoxides 2 which fills an important gap in the functional group interconversion of organosulfur compounds, the results of which we now describe.     

Comparison of different experimental methods for the assessment of the room’s acoustics

The paper presents the acoustics analysis of three different enclosed spaces. These spaces (rooms) have different geometrical shapes and sizes and serve for different purposes. The early decay time, reverberation time, clarity and center time are evaluated with Dirac, WinMLS, Aurora and Caracad software using simple, low-cost equipment. The listed acoustic parameters were determined using linear sine sweep and impulsive sources. Comparisons between experimental measurements, simulations and analytic results were done. The room impulse response measurement proved to be the most reliable method to evaluate the properties of different rooms even if the measurements are perturbed by non-idealities of the low-cost equipment.