X-ray Diffraction, FT-IR, and ¹³C CP/MAS NMR Structural Studies of Solvated and Desolvated C-Methylcalix[4]resorcinarene

Abstract

Solid C-methylcalix[4]resorcinarene solvated by acetonitrile and water (CAL-Me) and then modified by slow solvent evaporation (CAL-Me*) was studied using single-crystal and powder X-ray diffraction, FT-IR, and (13)C CP/MAS NMR. The CAL-Me solvate crystallizes in the monoclinic P2(1)/n space group with three CH(3)CN and two H(2)O molecules in the asymmetric part of the unit cell. The CAL-Me molecules adopt a typical crown conformation with all of the hydroxyl groups of the aryl rings oriented up and all of the methyl groups disposed down (the rccc isomeric form). The crystalline network is formed by resorcinarene, CH(3)CN, and H(2)O molecules and assembled by intermolecular hydrogen bonds and weak C-H...A or C-H...pi interactions. The desolvated CAL-Me* loses its crystalline character and becomes partly amorphous. It is devoid of CH(3)CN and deficient in water. However, the resorcinarene molecules still remain in the crown conformation supported by intramolecular hydrogen bonds, while intermolecular hydrogen bonds are considerably disintegrated. The work directs general attention to the problem of stability and polymorphism of resorcinarene solvates. It shows that the joint use of diffractometric and spectroscopic methods is advantageous in the structural studies of complex crystalline macromolecular systems. On the other hand, the solid-state IR and NMR spectroscopic analyses applied in tandem have been found highly beneficial to elucidate the disordered structure of poorly crystalline, desolvated resorcinarene.

Characterization of the Non-uniform Reaction in Chemically Amplified Calix[4]resorcinarene Molecular Resist Thin Films

“…The decrease in intensity could be due to the loss in contrast via loss in O content from the volatile protecting group products (CO 2 ). The mean distance between methyl-substituted bridging carbons was ,0.51 nm, [50] as found in CM4R co-crystals. It is hypothesized that the presence of the surface order may exclude photoacid generator, such that deprotection is kinetically limited by the less accessible t-Boc groups within the ordered domains and reduced average diffusivity of photoacid that remains blended with amorphous D-t-Boc-CM4R material at the surface.…”

Organic Nanocrystals of the Resorcinarene Hexamer via Sonochemistry: Evidence of Reversed Crystal Growth Involving Hollow Morphologies

“…32 The propensity of CMCR to form hydrates (and solvates in general) is well-documented. 33 When the nanocrystallization of the CMCR hexamer was repeated with vigorous stirring in water alone, the resulting solid was composed of smooth spherical particles that ranged from 40 to 900 nm in diameter (Figure S2). When the suspension was allowed to age for 2 months, no change in size or morphology was observed (Figure S3).…”

Conservation of a unique noncovalent motif in a tetracyanoresorcin[4]arene silver complex

“…Indeed, previous structural studies on RsC/ MeCN clathrates have also shown a similar interaction between the acetonitrile cyano group and the cavity of the RsC. 21…”