Diversity in Supramolecular Solid-State Architecture Formed by Self-Assembly of 1‑(Diaminomethylene)thiourea and Aliphatic Dicarboxylic Acids

A family of supramolecular complexes of 1-(diaminomethylene)­thiourea with aliphatic dicarboxylic acids, HOOC­(CH₂)_<i>n</i>COOH, with odd and even numbers of methylene groups in the carbon chain of the acids has been characterized. Using solvent-assisted and evaporation-based techniques, crystallization of 1-(diaminomethylene)­thiourea with aliphatic dicarboxylic acids from water solutions yielded ionic supramolecular complexes with base to acid ratio of 2:1 or 1:1. Malonic, succinic, adipic, and sebacic acids with 1-(diaminomethylene)­thiourea form supramolecular complexes of 2:1 ratio (<b>1</b>, <b>2</b>, <b>4</b>, and <b>8</b>), whereas glutaric, pimelic, azelaic, and suberic acids form supramolecular complexes of 1:1 ratio (<b>3</b>, <b>5</b>, <b>6</b>, and <b>7</b>). Within all supramolecular complexes only one with adipic acid crystallizes as a hydrate containing water molecules of crystallization. In the hydrated crystal with adipic acid, the O–H···O chains of water molecules interact with adipiate­(2-) anions forming anionic layers, and the charge is compensated by 1-(diaminomethylene)­thiouron-1-ium cations. The 2:1 supramolecular complexes further interact each other via N–H···O hydrogen bonds forming two- or three-dimensional supramolecular structure. Within 1:1 supramolecular complexes, the singly deprotonated aliphatic dicarboxylic acids are linked together via strong symmetrical O···H···O hydrogen bonds into infinitive chains. The chains are further linked by 1-(diaminomethylene)­thiouron-1-ium cations to form a two- or three-dimensional hydrogen bonding network. Interaction between the 1-(diaminomethylene)­thiouron-1-ium and the singly or doubly deprotonated aliphatic dicarboxylic acid units in solid of <b>1</b>–<b>8</b> supramolecular complexes were also analyzed by vibrational spectroscopy