Single electron transfer (SET) activity of the dialkyl-amido sodium zincate [(TMEDA)·Na(µ-TMP)(µ-tBu)Zn(tBu)] towards TEMPO and chalcone.

More usually thought of as a base, the sodium zincate [(TMEDA)·Na(µ-TMP)(µ-(t)Bu)Zn((t)Bu)] 1 can undergo single electron transfer with TEMPO to give [(TMEDA)·Na(µ-TMP)(µ-TEMPO(-))Zn((t)Bu)] 2 and [(TMEDA)·Na(µ-TEMPO(-))(2)Zn((t)Bu)] 3; and with chalcone [PhCOCH=CHPh] gives [{(TMEDA)·Na(µ-TMP)Zn((t)Bu)}(2)(µ-OCPhCH=CHPhCHPhCH=CPh-µ-O)] which contains two chalcone units C-C coupled though their benzylic C atoms.

Light scattering and cell volumes in osmotically stressed and frozen-thawed cells.

Recent reports, indicating that under some conditions the intensity of light scattering from cells is a nonlinear function of cell volume, have led to the widespread generalization that intensity of low-angle light scattering indicates cell size. This study was performed to measure the relationships between light scattering and cell volumes in an-isotonic solutions and after a freeze-thaw stress. Cell volumes in isolated human lymphocytes, human granulocytes, and hamster fibroblasts were deliberately altered by exposure to anisotonic solutions. Boyle-vant Hoff plots of cell volume as a function of inverse osmotic pressure showed that the cells behaved as osmometers. Similar plots of right-angle and low-angle light scattering showed that the intensity of light scattering varied inversely with cell volume. In other experiments where cells were frozen without cryoprotectant at various sub zero temperatures to -25 degrees C and then thawed rapidly, cell viability decreased progressively with decreasing temperature, as did the intensity of both low-angle and right-angle light scattering, although cell volumes remained relatively constant. The intensity of both low- and high-angle light scattering varied inversely with cell volumes in hypertonic and hypotonic solutions, but cell damage induced by freezing and thawing resulted in significant reductions in the intensity of low-angle light scattering with little change in cell volume. These observations show that light scattering and cell volumes can vary independently, and they underline the need for a better understanding of the phenomenon of light scattering from living cells.