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 (H4NTA) and 3,4,9,10-perylenetetracarboxylic acid (H4PTA), with amines (triethylamine, TEA; ethylenediamine, EDA) in H2O give four H-bonded
organic salts, [HTEA]2·[H2NTA]·2H2O (1), [HTEA]2·[H2PTA] (2), [H2EDA]2·[NTA]·3H2O (3), and [H2EDA]2·[PTA]·8H2O (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 H2EDA2+ 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···O H-bonds between H2O and H2NTA2- and contains
a normal graph set of R24(8) (formed by two H2O and two carboxyl O atoms). Different from 1, 2 contains a 1-D structure with an
R22(16) ring formed by O−H···O H-bonds between H2PTA2-. Both 3 and 4 have 3-D framework structures with well-defined 1-D
channels, assembled by complicated N−H···O and O−H···O H-bonds. All the O and amino H atoms in H2EDA2+ and NTA4- or
PTA4- 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, H4PTA 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.

在水溶液中，将两种芳香族四羧酸——1,4,5,8-萘四甲酸（1,4,5,8-naphthalenetetracarboxylic acid, H4NTA）与3,4,9,10-苝四甲酸（3,4,9,10-perylenetetracarboxylic acid, H4PTA）——分别与胺类试剂（三乙胺（triethylamine, TEA）、乙二胺（ethylenediamine, EDA））进行结晶反应，得到四种氢键键合有机盐：[HTEA]₂·[H₂NTA]·2H₂O（1）、[HTEA]₂·[H₂PTA]（2）、[H₂EDA]₂·[NTA]·3H₂O（3）与[H₂EDA]₂·[PTA]·8H₂O（4），所有产物均通过X射线衍射完成结构表征。在以TEA为胺源的盐（1和2）中，每种羧酸均转移两个质子，超分子氢键实体仅由羧酸阴离子（或辅以结晶水）构建；而在3和4中，羧酸的全部四个质子均发生转移，乙二胺阳离子（H₂EDA²⁺）与羧酸阴离子共同参与最终骨架的构筑，这一现象可能源于两种胺的碱性差异。盐1具有层状结构，由结晶水与H₂NTA²⁻之间的O−H···O氢键稳定，且存在经典的R₂⁴(8)图集（由两个结晶水分子与两个羧基氧原子构成）。与盐1不同，盐2呈现一维结构，其特征为由H₂PTA²⁻之间的O−H···O氢键形成的R₂²(16)环。盐3与盐4均拥有三维骨架结构，且带有规整的一维通道，二者均通过复杂的N−H···O与O−H···O氢键组装而成。H₂EDA²⁺与NTA⁴⁻、PTA⁴⁻中的所有氧原子及氨基氢原子均参与了氢键连接；尽管二者的共结晶水数目不同，但其晶体结构仍存在显著差异。值得关注的是，盐3中的一维通道呈圆形，内部由单条水分子链填充；而盐4中的通道为矩形，内部填充了具有T4(2)6(2)结构的水分子带。本研究表明，体积更大且氢键作用方式单一的TEA可作为终端氢键构筑单元，用于构建低维网络；而具有良好柔性与多样氢键作用模式的EDA则可连接羧酸组分，形成高维骨架结构。此外，H4PTA被证实是一种极具研究价值的氢键型分子构筑基元，在晶体工程领域，尤其是制备具有大空腔/通道的材料方面具有巨大潜力。本研究还对盐4的稳定性与发光性能进行了初步探究。