Packing Similarities and Synthon Variabilities in Aminopyridinium Sulfoisophthalates

Abstract

Different salts of 5-sulfoisophthalic acid with aminosubstituted monocyclic Lewis bases: 2-aminipyridine, 3-aminopyridine, 4-aminopyridine, 2,6-diaminopyridine, have been prepared and studied by means of X-Ray crystallography, FTIR and Raman spectroscopy and TG-DTA and DSC methods. The crystal networks have been analyzed in view of competitive hydrogen bond interactions issued between multiple functional groups in different topological and stoichiomeric combinations allowing for formation of variable synthons. A statistical analysis of the most prominent homo-and heteromeric motifs, which can be formed between the functional groups, has been performed with the use of Mercury Solid Form module in order to look for preferred interactions in extended network formation. Eighteen different synthons are used in the presented crystal networks some of which are really prolific and other are unique. The role of water molecule for the network formations using four different water synthons is also elucidated.

Sulfonate···Pyridinium Supramolecular Synthon: A Robust Interaction Utilized to Design Molecular Assemblies

“…Besides strength and directionality, the defining criterion for a robust supramolecular synthon is its frequency of occurrence. Although reported few and far between, − sulfonate···pyridinium interactions are not categorized as robust supramolecular synthons. , Our recent account of supramolecular assemblies based on this synthon indicated its facile manifestation . Molecular salts 1 – 6 further indicate persistent sulfonate···pyridinium synthon formation, even in the presence of other possible competing interactions.…”

“…In 3 and 6 , the synthon is masked by solvent molecules, while in 4 and 5 sulfonate and pyridinium centers are in direct contact. Synthon masking has been reported previously for sulfonate···pyridinium as well as other supramolecular synthons. , The articulation of the sulfonate ···pyridnium synthon in 1 , 1a , and 2 is debatable. In addition to being a structural unit and assembled through a known synthetic operation, a supramolecular synthon should be clung to by intermolecular interaction .…”

“…It was also observed that in addition to thermal and chemical stability, proton transfer leads to incipience of color in the products of colorless pristine formers. These results prompted us to further investigate the sparsely reported sulfonate···pyrdinium synthon. − In addition to fewer hits than for the corresponding carboxylic acid···pyridine synthon, our CCDC search indicated a large tendency for proton transfer of the sulfonic proton to pyridyl nitrogen, i.e., salt formation in the sulfonic acid pyridine-based synthon, Chart . Here, we report a series of supramolecular aggregates utilizing aryl-sulfonic acid and various pyridyl derivatives (Chart ), as a case for consideration of sulfonate···pyridinium interaction as a robust supramolecular synthon.…”

Structural Isomerization of 2-Anilinonicotinic Acid Leads to a New Synthon in 6-Anilinonicotinic Acids

“…Structurally, they still possess partial double bond property for the corresponding C–N bond (Figure a), which should again lead to E and Z configurational isomers, and the intramolecular hydrogen bond between NH and CO is no longer feasible. Will the acid–acid homosynthon (2a) be preferred or the acid–pyridine heterosynthon (2c) be favored, or will new synthons such as the acid–aminopyridine (2d) and the aminopyridine–aminopyridine (2b) emerge in the newly designed 6-ANAs − (Figure )? Investigation of 6-ANAs should shed light on the relationship between the location of functional groups and/or conformation and crystal packing (e.g., polymorphism) and also contribute to the field of crystal structure prediction. − …”