The Crystal and Molecular Structure of the Antihistaminic Drug Triprolidine Hydrochloride Monohydrate [trans-1-(p-Tolyl)-1-(2-pyridyl)-3-(1-pyrrolidino)-prop-1-ene

Abstract

The title compound crystallizes from anisole with 4 molecules per unit cell. The space group of this cell is P21/c and the cell parameters are a = 14.777(2) Å, b = 9.5785(8) Å, c = 13.099(1) Å, and β = 90.48(2)°. Diffractometer data with CuKα radiation to 2θ = 129° were collected and the structure solved and refined to weighted and unweighted R factors of 0.077 and 0.051 respectively. The 2-pyridyl ring and the p-tolyl system make dihedral angles of 29.7 and 55.3° respectively with the plane of the double bond. The inter-aryl dihedral angle is 106.5°. The protonated tertiary nitrogen atom is hydrogen bonded to the chloride ion and two chloride ions are connected via hydrogen bonds in a distorted square planar arrangement by two water molecules. The pyridyl ring is involved in a π orbital overlap linkage with another pyridyl ring on the same side of the molecule as is the hydrogen bond from the nitrogen function. Brief characteristics of a flexible receptor protein which will bind antihistamine drugs are given.