TY - JOUR

T1 - Co-crystals of polyhalogenated diaminobenzonitriles with 18-crown-6: effect of fluorine on the stoichiometry and supramolecular structure

AU - Vaganova, Tamara A.

AU - Gatilov, Yurij V.

AU - Malykhin, Sergey E.

AU - Pishchur, Denis P.

AU - Sukhov, Maxim

AU - Zakharov, Boris A.

AU - Boldyreva, Elena V.

AU - Malykhin, Evgenij V.

N1 - Publisher Copyright: © The Royal Society of Chemistry 2021.

PY - 2021/7/21

Y1 - 2021/7/21

N2 - A series of polyhalogenated diaminobenzonitriles and 18-crown-6 ether were used to reveal the dependence of the stoichiometry and supramolecular structure of co-crystals on various factors. 2,6-Diamino-3,5-difluoro-, 2,6-diamino-4-chloro-3,5-difluoro-, and 2,6-diamino-4-chloro-3-fluorobenzonitriles, as well as 2,4-diamino-3,5-difluorobenzonitrile give 1 : 1 co-crystals regardless of the diamine : crown ratio in the crystallization solution (from 2.5 : 1 to 1 : 2.5) and the nature of the solvent. According to X-ray diffraction data, the supramolecular structures of these co-crystals can be considered as 1D assemblies with the only structure-forming N-H⋯Ocrhydrogen bond. 2,4-Diamino-3,5,6-triflurobenzonitrile forms no 1 : 1 co-crystal, but yields co-crystals of 4 : 3 (under most of the studied conditions) and 2 : 1 (in CCl4solution) stoichiometry. The N-H⋯NC hydrogen bond and p⋯π electron interactions, along with the N-H⋯OcrH-bond, participate in the formation of the 3D supramolecular structures of these co-crystals. The effect of the number of F atoms on the co-crystallization behaviour of difluoro- and trifluoro-2,4-diaminobenzonitriles was rationalized using quantum-chemical computations of the interaction energies of N-H⋯NC bonded pairs of these diamines in the experimental crystals and DFT simulated models. The DSC curves of each co-crystal contain a single peak corresponding to a crystal-to-liquid phase transition (melting), which does not change in melting-crystallization cycles, indicating that the stoichiometry and crystal structure are reproducible.

AB - A series of polyhalogenated diaminobenzonitriles and 18-crown-6 ether were used to reveal the dependence of the stoichiometry and supramolecular structure of co-crystals on various factors. 2,6-Diamino-3,5-difluoro-, 2,6-diamino-4-chloro-3,5-difluoro-, and 2,6-diamino-4-chloro-3-fluorobenzonitriles, as well as 2,4-diamino-3,5-difluorobenzonitrile give 1 : 1 co-crystals regardless of the diamine : crown ratio in the crystallization solution (from 2.5 : 1 to 1 : 2.5) and the nature of the solvent. According to X-ray diffraction data, the supramolecular structures of these co-crystals can be considered as 1D assemblies with the only structure-forming N-H⋯Ocrhydrogen bond. 2,4-Diamino-3,5,6-triflurobenzonitrile forms no 1 : 1 co-crystal, but yields co-crystals of 4 : 3 (under most of the studied conditions) and 2 : 1 (in CCl4solution) stoichiometry. The N-H⋯NC hydrogen bond and p⋯π electron interactions, along with the N-H⋯OcrH-bond, participate in the formation of the 3D supramolecular structures of these co-crystals. The effect of the number of F atoms on the co-crystallization behaviour of difluoro- and trifluoro-2,4-diaminobenzonitriles was rationalized using quantum-chemical computations of the interaction energies of N-H⋯NC bonded pairs of these diamines in the experimental crystals and DFT simulated models. The DSC curves of each co-crystal contain a single peak corresponding to a crystal-to-liquid phase transition (melting), which does not change in melting-crystallization cycles, indicating that the stoichiometry and crystal structure are reproducible.

UR - http://www.scopus.com/inward/record.url?scp=85109920872&partnerID=8YFLogxK

U2 - 10.1039/d1ce00530h

DO - 10.1039/d1ce00530h

M3 - Article

AN - SCOPUS:85109920872

VL - 23

SP - 4767

EP - 4781

JO - CrystEngComm

JF - CrystEngComm

SN - 1466-8033

IS - 27

ER -