Synthesis And Crystal Structures Of Hydrogen Bonded Inclusion Compounds Built With Thiourea Derivatives And Multi-Carboxylic Aromatic Compounds

Herein we report 10 novel crystal structures which include 9 inclusion compounds and 1 adduct. In these compounds, with the existence of ancillary molecules such as bicarbonate, guanidinium and water molecules, the host molecules of planar thiourea derivatives of dithiobiurea and guanylthiourea and V-shaped multi-carboxylic acids are selected to interact with the guest templates of tetraalkylammonium ions to generate various crystal structures. All the compounds were determined by single X-ray diffraction analysis. According to the host molecules, these 10 crystals can be divided into two categories. 1. Thiourea derivatives:(a) Hydrogen-bonded inclusion compounds of dithioubiurea: Two inclusion compounds of 2.1 and 2.2 were synthesized with dithioubiurea and tetraalkylammonium guest templates. In these two inclusion compounds, although the host molecule is same, the final crystal structures are very different due to the different guest molecules. Interestingly, dithiobiurea is easy to lose its proton to form the dimmer to act as the basic constructing unit of the related hydrogen bond layers.(b) Hydrogen-bonded inclusion compounds of guanylthiourea: Guanylthiourea is a planar hydrogen bond reagent that can be regarded as the combination of triangle amidine and thiourea. Herein 5 inclusion compounds were prepared with guanylthiourea and auxiliary molecules such as bicarbonate anion and water molecular with the existence of tetraalkylammonium guest templates. Among these compounds, 2.3, 2.4 and 2.5 are sandwich-like structures, and 2.5 and 2.6 are tubular structures.(c) Guanylthiourea adduct: The adduct of 2.4 with tubular structure was synthesized by guanylthiourea, 3-nitrophthalic acid and water molecule. The results prove that 3-nitrophthalic acid tends to deprotonate to be a good hydrogen bond acceptor. 2. V-shaped aromatic tetra-carboxylic acid: We choose two V-shaped aromatic tetra-carboxylic acids to act as the host molecules to interact with tetraalkylammonium guest templates to get new inclusion compounds(3.1 and 3.2) with the existence of the auxiliary guanidinium molecules. In 3.1, 4,4′-oxidiphthalic acid( H4odpa) is a good hydrogen bond acceptor and guanidinium is a fine donor. Although there are only 4 kinds of hydrogen bonds in this compound, the number of hydrogen bonds is 49 and the connection modes of the hydrogen bonds are complicated. In addition, the asymmetric 3-(3′, 5′-dicarboxylphenoxy) phthalic acid( H4dcppa) as the host molecule, we get hydrogen bond inclusion compound 3.2 of channel structure in the same as other conditions. Compared to 3.1, due to the difference carboxyl position of V-shaped carboxylic acid eventually leads to different crystal structure, under the condition of that ancillary molecules and tetraalkylammonium guest templates are same.By studying these crystal structures, it is helpful to further understand the hydrogen bonding and other weak molecular interactions. Obviously, it provides the related references to design crystal structure and directs us to synthesize other novel hydrogen-bond inclusion compounds with different properties.