2003 Volume 19 Pages x1-x2
Crystals of 2-trifluoromethyl-4′-dimethylaminoazobenzene (2-TFMDAB) are orthorhombic, space group Pbca with a =15.625(4), b = 23.028(6), c = 7.685(2)Å, and Z = 8. The structure was solved by direct methods (SIR88) and refined to a final R value of 0.049 for 2536 reflections (I>0.80σ(I)). 2-TFMDAB has a trans geometry about the azo linkage. The bond lengths and angles are similar to those of other azobenzene compounds. The abnormal UV-vis absorption spectrum in an acidic solution can be explained by the existence of the bulky and electronegative CF3 group at the 2-position, which prevents protonation at the Nβ atom of the azo group in an acidic solution.
