Hydrogen-bonded assembly of aminophosphonic anions: different 1D, 2D and 3D supramolecular architectures

Abstract

In order to investigate hydrogen-bonded assembly of aminophosphonic anions, six novel organic acid–base compounds including (AEDPH₂)·(1,3-pnH₂)·H₂O (1), (AEDPH₂)·(1,2-pnH₂)·H₂O (2), (AEDPH₂)·(pipH₂)·H₂O (3), (AEDPH₃)·(pipH₂)_0.5·3H₂O (4), (APDPH₃)·(pipH₂)_0.5 (5) and (APDPH₃)·(enH₂)_0.5 (6), as well as hydrate compounds (AEDPH₃)·H₃O (7) and (APDPH₃)·H₃O (8) (AEDPH₄ = 1-aminoethylidenediphosphonic acid, APDPH₄ = 1-aminopropane-1,1-diphosphonic acid, 1,2-pn = 1,2-propylenediamine, 1,3-pn = 1,3-propylenediamine, pip = piperazin, en = ethylenediamine), were synthesized and characterized. The aminophosphonic acids in these compounds are deprotonated to form anions with different valences and show various structural aggregates: The AEDPH₂²⁻ anions form one-dimensional (1D) zigzag supramolecular chains with different chain lengths and angles in compounds 1 and 2, while create 1D linear double supramolecular chain in compound 3. The monovalent aminophosphonic anions generate two-dimensional (2D) supramolecular layers with different layer to layer distances in compounds 4–6, but display 3D supramolecular framework in compounds 7 and 8. In particular, compound 4 contains a 1(1)3(1)R4 water cluster. The factors which influence hydrogen-bonded assembly of aminophosphonic anions, including structure of diamine, C: A ratio and substitutional group of aminophosphonic acid, are all discussed in detail.