Crystal engineering and structural investigations of the 2-amino-5-nitropyridinium salts C5H6N3O2 +.HSO4 − and C5H6N3O2 +.H2AsO4 −

The aim of studying the encapsulation of 2-amino-5-nitropyridinium cations in (HSO 4 - ) n and (H 2 AsO 4 - ) n polymeric host matrices is to build acentric frameworks that are efficient for quadratic nonlinear optical applications. Evidence is given for the role of inorganic polyanions in the formation of polar packings and this is discussed on the basis of X-ray crystal structure investigations. C 5 H 6 -N 3 O 2 + .HSO 4 - is orthorhombic, Pcab, with a=29.617 (9), b=13.185 (3), c=9.013 (2) A, Z=16: the crystal structure has been solved using direct methods and difference Fourier syntheses, with a reliability factor R=0.049 for 2483 independent reflections