Photochemical Properties of the Red-shifted Channelrhodopsin Chrimson.

Color-tuned variants of channelrhodopsins allow for selective optogenetic manipulation of different host cell populations. Chrimson is the channelrhodopsin with the longest wavelength absorbance maximum. We characterize its photochemical properties at different pH values corresponding to two protonation states of the counterion for the protonated Schiff base.

Nimustine hydrochloride: the first crystal structure determination of a 2-chloroethyl-N-nitrosourea hydrochloride derivative by X-ray powder diffraction and solid-state NMR.

Nimustine hydrochloride [systematic name: 4-amino-5-({[N-(2-chloroethyl)-N-nitrosocarbamoyl]amino}methyl)-2-methylpyrimidin-1-ium chloride], C(9)H(14)ClN(6)O(2)(+)·Cl(-), is a prodrug of CENU (chloroethylnitrosourea) and is used as a cytostatic agent in cancer therapy. Its crystal structure was determined from laboratory X-ray powder diffraction data. The protonation at an N atom of the pyrimidine ring was established by solid-state NMR spectroscopy.