Synthesis, structure and vibrational spectra of d,l-histidinium 9,10-dihydro-9-oxo-10-acridineacetate tetrahydrate

Abstract

The preparation, crystal structure and vibrational spectra are reported for d,l-HistH +·CMA −·4H 2O, where the CMA −=9,10-dihydro-9-oxo-10-acridineacetate anion. The salt crystallizes in the P 1 ̄ space group, with cell dimensions a=8.341(4), b=9.573(4), c=15.509(4) Å, α=102.38(4)°, β=101.26(4)°, γ=106.77(4)°, Z=2. The structure was solved by direct methods and refined by full-matrix least-squares to R=0.0363 for 2436 non-zero reflections. The crystal comprises CMA − anions, histidinium cations and water molecules which are held together by a number of hydrogen bonds. The CMA moieties form the stacks whereas the histidinium cations are present as cyclic hydrogen bonded dimers. The conformation of histidinium is the “gauche-closed”. IR and Raman spectra are presented and a tentative assignment is made.