Molecular Recognition Induced Supramolecular Array of 2-Aminopyrimidine with Terephthalic Acid, 1,4-Phenylenediacetic Acid and Fumaric Acid in Solid State via H-bonding and π-stacking Interactions*

Abstract

The crystal structures of molecular complexes of 2-aminopyrimidine (2AP) with terephthalic acid (1) (1:1; Complex A), 1,4-phenylenediacetic acid (2) (1:1; Complex B) and fumaric acid (3) (1:2; Complex C) were determined. Complex A is orthorhombic, space group Pnma, with α = 13.0323(3), b = 23.9443(1), c = 3.7927(1) Å α = β = γ = 90° Z = 4; Dcalc = 1.466 Mg/m3; final R = 0.0384, wR 2 = 0.0939 for 1381 independent reflections. Complex B is orthorhombic, space group Pben with α = 4.5686(1), b = 15.7687(2), c = 20.1621(4) A; α = β = γ = 90° Z = 4; Dcalc = 1.323 Mg/m3; final R = 0.0461, wR 2 = 0.1158 for 1662 independent reflections. Complex C is monoclinic, space group P21/c with α = 3.7946(2), b = 19.1766(7), c = 13.0641(6) Å α = 90°, β = 96.893(1)°, γ = 90° Z = 4; Dcalc = 1.486 Mg/m3; final R = 0.0665, wR 2 = 0.1626 for 2752 independent reflections. 2AP generates supramolecular assembly with 2 and 3 via non-conventional weak C‒H‒O hydrogen bonding. Interestingly only in the case of Complex C, proton transfer occurs to the ring nitrogen of 2AP from 3. A novel hydrogen-bonding motif for the control of solid-state structures has been developed. The motif is based on the hydrogen bonding complementarity of dicarboxylic acids with 2AP.