Structural Landscape of α-Acetamidocinnamic Acid Cocrystals with Bipyridine-Based Coformers: Influence of Crystal Packing on Their Thermal and Photophysical Properties

Controlling the supramolecular synthon outcome in systems with different functionalities has been a key factor for the design of supramolecular materials, which also affected their physicochemical properties. In this contribution, we have analyzed the structural landscape of α-acetamidocinnamic acid (HACA) aiming to find its synthon outcome from the competitivity between its acidic and amidic groups. We prepared four multicomponent forms including one dihydrate (HACA·2H2O) and three cocrystals bearing different bipyridine coformers with formulas (HACA)2(1,2-bpe) (1), (HACA)2(4,4′-azpy) (2), and (HACA)2(4,4′-bipy)3 (3) (1,2-bpe = 1,2-bis(4-pyridyl)ethylene; 4,4′-azpy = 4,4′-azopyridine; 4,4′-bipy = 4,4′-bipyridine). First, we applied a virtual screening approach to assess the feasibility of cocrystal formation. Then, we synthesized the cocrystals, via liquid-assisted grinding (LAG) (1 and 2) or solvothermal (3) techniques, and single crystals of HACA, and their four multicomponent forms were obtained showing different synthons and crystal packings. Besides, a Cambridge Structural Database (CSD) search of the cocrystals presenting bipyridine-type coformers and molecules with acid and amide functionalities was performed, and the observed synthon occurrences as well as the possibility of synthon modification by tuning the H-donor/H-acceptor propensity of the acidic and amidic groups were shown. Finally, we measured their thermal and photophysical properties, which were correlated with their structural features.


Figure S1 .
Figure S1.XRD patterns from the single crystal collected data at 100 K and powder XRD pattern at 298 K of HACA.

Figure
Figure S2.XRD patterns from the single crystal collected data at 100 K and powder XRD pattern at 298 K of HACA•2H2O.

Figure
Figure S18.(a) Hirshfeld surfaces of HACA dihydrate crystal structure mapped with (a) dnorm and (b) curvedness representations.(c) 2D fingerprint plots of HACA single crystal.(d and e) Hirshfeld surfaces mapped with dnorm representation and 2D fingerprint plots of the water molecules of HACA dihydrate structure.

Table S1 .
CSD results of the cocrystal structures containing acid and amide groups with bipyridine-based coformers.
a Synthon outcome types are specified in figure7bof the manuscript.

Table S2 .
Melting point values of the utilized components and the resulting crystalline forms of this work.All the melting points have been determined using the same apparatus detailed in the experimental section of the manuscript. a

Table S3 .
Contribution and lattice energies of the crystal structures of HACA, HACA•2H2O and cocrystals 1-3.All the values have been obtained using CrystalExplorer 17.5 from the corresponding .ciffiles.a All the energies are given in KJ/mol; b Eele = electrostatic energy; c Epol = electrostatic energy; c Edis = dispersion energy; d Erep = repulsion energy; e Etot = total energy; f Elatt = lattice energy.h Rows with repeated components in each specific compound stands for different types of this molecule within the crystal structure. a