Kolloide: Die Welt der vernachlässigten Dimensionen

Aquatic colloids are abundant in all natural aquatic systems. Aquatic colloids consist of clay minerals, micro‐organisms, humic substances, and anthropogenic colloids like soot and platinum (from catalysts in motor vehicles). Colloids may enhance contaminant transport due to sorption of hydrophobic organic compounds. They can have negative effects on water quality, especially micro‐organisms like pathogens or viruses. Colloids also can cause pore blocking and subsequent head loss in groundwater production wells. However, colloids can be useful in groundwater remediation or waster water treatment (e.g. tensides, flocculation, catalysts). The origin of colloids is due to weathering, degradation of organic compounds, dissolution or precipitation as well as hydrochemical or hydraulic gradients. Colloid stability is dominated by surface properties. New analytical tools like field flow fractionation, laser induced breakdown detection and scanning x‐ray microscopy will provide new insight into the behaviour of aquatic colloids.     

Unprecedented Nucleophilic Additions of Highly Polar Organometallic Compounds to Imines and Nitriles Using Water as a Non‐Innocent Reaction Medium

In contrast to classic methods carried out under inert atmospheres with dry volatile organic solvents and often low temperatures, the addition of highly polar organometallic compounds to non‐activated imines and nitriles proceeds quickly, efficiently, and chemoselectively with a broad range of substrates at room temperature and under air with water as the only reaction medium. Secondary amines and tertiary carbinamines are furnished in yields of up to and over 99 %. The significant solvent D/H isotope effect observed for the on‐water nucleophilic additions of organolithium compounds to imines suggests that the on‐water catalysis arises from proton transfer across the organic–water interface. The strong intermolecular hydrogen bonds between water molecules may play a key role in disfavoring protonolysis, which occurs extensively in other protic media such as methanol. This work lays the foundation for reshaping many fundamental s‐block metal‐mediated organic transformations in water.     

Label-Free Imaging of Intracellular Temperature by Using the O−H Stretching Raman Band of Water

We propose a label-free method for measuring intracellular temperature using a Raman image of a cell in the O−H stretching band. Raman spectra of cultured cells and the medium were first measured at various temperatures using a Raman microscope and the intensity ratio of the two regions of the O−H stretching band was calculated. The intensity ratio varies linearly with temperature in both the medium and cells, and the resulting calibration lines allow simultaneous visualization of both intracellular and extracellular temperatures in a label-free manner. We applied this method to the measurement of temperature changes after the introduction of FCCP (carbonyl cyanide-p-trifluoromethoxyphenylhydrazone) in living cells. We observed a temperature rise in the cytoplasm and succeeded in obtaining an image of the change in intracellular temperature after the FCCP treatment.