Hydrogen-bonded supramolecular architectures of organic salts based on aromatic tetracarboxylic acids and amines

Crystallizations of two aromatic tetracarboxylic acids, 1,4,5,8-naphthalenetetracarboxylic acid (H(4)NTA) and 3,4,9,10- perylenetetracarboxylic acid (H(4)PTA), with amines (triethylamine, TEA; ethylenediamine, EDA) in H2O give four H-bonded organic salts, [HTEA](2)center dot[H(2)NTA]center dot 2H(2)O (1), [HTEA](2)center dot[H(2)PTA] (2), [H(2)EDA](2)center dot[NTA]center dot 3H(2)O (3), and [H(2)EDA](2)center dot[PTA]center dot 8H(2)O (4), which were structurally characterized by X-ray diffraction. In the TEA salts (1 and 2), two protons of each acid are transferred and the supramolecular H-bonded entities are generated by only acid anions (or together with H2O), whereas in 3 and 4 all four protons are transferred and both H(2)EDA(2+) and acid anions contribute to the final framework formation, probably due to the differences in basicities of the two amines. Salt 1 has a layer structure stabilized by O-H center dot center dot center dot O H-bonds between H2O and H(2)NTA(2-) and contains a normal graph set of R-4(2)(8) (formed by two H2O and two carboxyl O atoms). Different from 1, 2 contains a 1-D structure with an R-2(2)(16) ring formed by O-H center dot center dot center dot O H-bonds between H(2)PTA(2-). Both 3 and 4 have 3-D framework structures with well-defined 1-D channels, assembled by complicated N-H center dot center dot center dot O and O-H center dot center dot center dot O H-bonds. All the O and amino H atoms in H(2)EDA(2+) and NTA(4-) or PTA(4-) participate in the H-bonding linkages; however both salts have great structural differences with different numbers of cocrystallized H2O. It is interesting that the 1-D channels in 3 are circular and occupied by single H2O line but those in 4 are rectangular and filled by H2O tapes with a T4(2)6(2) pattern. Herein, TEA with a larger volume and simple H-bonding manner is considered as a terminal H-bonding moiety to form low-dimensional networks, whereas EDA with favorable flexibility and various H-bonding modes is adopted to link the acid components to give higher dimensional frameworks. In addition, H(4)PTA seems to be proven as an interesting H-bonding molecular tecton with great potential in crystal engineering, especially for preparing materials with large cavities/channels. The stability and luminescent property of 4 have also been studied preliminarily.