Remarkable reversal of melting point alternation by co-crystallization

Interdependence of structure and physical properties in co-crystals of azopyridines

“…All datasets were collected at 120 K using APEX2 software. An Oxford Cryostream 700 low-temperature device was used to 10 control temperature. MoK radiation was used.…”

“…In co-crystals of 4,4'-azpy with succinic, adipic, suberic and sebacic acid (Fig 4 and 5a-c), structural consistency is maintained as we systematically increase the length of the diacid. 10 Consequently, co-crystal melting points show a near-linear correlation with the carbon chain length in the corresponding diacids, which indicates a strong and predictable structureproperty interdependence. The melting points of the pure diacids also decrease upon moving from shorter to longer chain acids.…”

“…With the help of reliable control of the intermolecular assembly, physical properties like thermal stability, 40 dissolution and solubility may be correlated in a predictable manner with molecular structure. 9,10 Previously, we demonstrated how a careful selection of cocrystallizing agents, provide structural control leading to either 1-D networks or 0-D assemblies, focusing mainly on the primary 45 synthons with less emphasis on weaker interactions. 11 In our current study, we highlight how weaker secondary interactions influence the organization of 1-D motifs into assemblies of higher dimensionality, as well as on possible connections between structural consistency and reliable structure- 50 property correlation.…”

“…It seems that 60 more structural data is needed in order to find a plausible Based on the analysis of crystal structures and corresponding melting points of 3,3'-and 4,4'-azpy co-crystals, we can 5 conclude that these two bipy-related compounds are very efficient at forming co-crystals with aliphatic dicarboxylic acids. Furthermore, if structural control can be maintained within a series of related co-crystals, it is possible to estimate the how physical properties may trend or even their relative magnitude 10 purely based on the molecular structure of one of the two components. Finally, the relative positions of binding sites on related compounds can also be used to prepare new solid-forms that display physical properties that can be fine-tuned with respect to those of the individual components.…”

“…Thermal behaviour of azopyridine:diacid co-crystals 10 The melting point of any solid is a fundamental physical property that may also have important implications for a range of applications, as well as for processing and shelf-life. If molecular structure and thermal behaviour can be interrelated, then we can modulate the physical properties of a library of compounds using 15 simple co-crystallization techniques.…”