Intermolecular Interactions Drive the Unusual Co-Crystallization of Different Calix[4]arene Conformations

Taylor, Dominic; Ling, Irene; Vilela, Filipe; Dalgarno, Scott J.

doi:10.3390/cryst12020250

Cited by 2 publications

(2 citation statements)

References 35 publications

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“…Vilela and Dalgarno observed unusual cocrystallization of two different calix [4]diquinone conformations (partial cone and 1,3-alternate) within a single crystal. 45 These complex crystal structures give us better insight into nuances of the host−guest molecular recognition and crystallization as second-order supramolecular process showcasing various scenarios from the host−guest structural landscape.…”

Section: Crystal Structure Of the Cpa5−alexidine Complexmentioning

confidence: 99%

Carboxylated Pillar[5]arene Meets Medicinal Biguanides: Host–Guest Complexes with Alexidine and Phenformin in the Crystal and Solution/Gas Phase

Butkiewicz,

Kosiorek,

Sashuk

et al. 2023

Crystal Growth & Design

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Here, we discuss crystal and solution/gas-phase complexes of carboxylated pillar [5]arene with two cationic guests, alexidine and phenformin, revealing host−guest and assembly curiosities, the role of hydrogen bonding, and cavity inclusion versus exo-mode binding. We show that the combination of carboxylated pillar[5]arene with bis(biguanidinium) guest alexidine results in the crystallization of open-type supramolecular architecture. This is also the first crystal structure of alexidine ever reported. The crystallization of pillar[5]arene with biguanidinium drug phenformin affects a rare solid-state complex comprising two cavity inclusion modes within the same crystal lattice. The winner in the competition between ethanol molecules and an organic cation (phenformin) for access to the cavity of pillar[5]arene is undecided, visualized as a "snapshot" of these two inclusion possibilities in one crystal structure. Our results demonstrate that carboxylated pillar[n]arenes can be a useful addition to the macrocyclic toolkit for the facilitation of the crystallization of bio(macro)molecules. Moreover, the IM-MS analysis of the precrystallization solutions of pillar[5]arene host and biguanide guests has shown the presence of structures and conformations closely related to those observed in the crystal forms. The most intriguing results obtained for a pillar[5]arene−alexidine complex imply a conformational evolution of the complex over 24 h. The IM-MS analysis complemented by theoretical calculations may be applied to predict and examine the crystallization process of host−guest systems, complementing crystallographic studies.

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Section: Crystal Structure Of the Cpa5−alexidine Complexmentioning

confidence: 99%

Carboxylated Pillar[5]arene Meets Medicinal Biguanides: Host–Guest Complexes with Alexidine and Phenformin in the Crystal and Solution/Gas Phase

Butkiewicz,

Kosiorek,

Sashuk

et al. 2023

Crystal Growth & Design

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“…For the hexahomotrioxacalix [3]arene, the situation is more simple as only two conformations are possible: cone and partial cone [32]. If the conformation is not blocked by a bulky substituent on the lower rim, the conformations are in equilibrium and interesting examples of crystals with the coexistence of more than one conformer have been reported [33,34]. In previous studies of one of the coauthors, theoretical and solution investigations on the complexation of lanthanide ions by these three macrocycles were reported [26].…”

Section: Introductionmentioning

confidence: 99%

Pseudo-Polymorphism in 2-Pyridylmethoxy Cone Derivatives of p-tert-butylcalix[4]arene and p-tert-butylhomooxacalix[n]arenes

Joshi,

Hickey,

Marcos

et al. 2024

Crystals

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This paper investigates pseudo-polymorphism in 2-pyridylmethoxy derivatives of p-tert-butylcalix[4]arene (PyC4), p-tert-butyldihomooxa-calix[4]arenes (PyHOC4), and p-tert-butylhexahomotrioxacalix[3]arenes (PyHO3C3), presenting 11 crystal structures with 15 crystallographically independent molecules. The macrocycle of PyC4 is smaller and less flexible with respect to those of PyHOC4 and PyHO3C3, and in solution, the cone conformation of these three molecules exhibits different point symmetries: C4, Cs, and C3, respectively. A correlation is observed between the macrocycle’s structural rigidity and the number of pseudo-polymorphs formed. The more rigid PyC4 displays a higher number (six) of pseudo-polymorphs compared to PyHOC4 and PyHO3C3, which exhibit a smaller number of crystalline forms (three and two, respectively). The X-ray structures obtained show that the conformation of the macrorings is primarily influenced by the presence of an acetonitrile guest molecule within the cavity, with limited impact from crystal packing and intermolecular co-crystallized solvent molecules. Notably, both calix[4]arene derivatives produce a host–guest complex with acetonitrile, while the most flexible and less aromatic PyHO3C3 does not give crystals with acetonitrile as the guest. Intertwined 1D and 2D solvent channel networks were observed in the PyHOC4-hexane and in the PyHO3C3-H2O-MeOH crystal structures, respectively, while the other pseudopolymorphs of PyHOC4 and PyHO3C3 and all PyC4 crystal forms exhibit closely packed crystal structures without open channels.

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Intermolecular Interactions Drive the Unusual Co-Crystallization of Different Calix[4]arene Conformations

Cited by 2 publications

References 35 publications

Carboxylated Pillar[5]arene Meets Medicinal Biguanides: Host–Guest Complexes with Alexidine and Phenformin in the Crystal and Solution/Gas Phase

Carboxylated Pillar[5]arene Meets Medicinal Biguanides: Host–Guest Complexes with Alexidine and Phenformin in the Crystal and Solution/Gas Phase

Pseudo-Polymorphism in 2-Pyridylmethoxy Cone Derivatives of p-tert-butylcalix[4]arene and p-tert-butylhomooxacalix[n]arenes

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