Unusual Behavior of a Calix[4]arene Featuring the Coexistence of Basic Cone and 1,2-Alternate Conformations in a Solvated Crystal

Abstract

b S Supporting Information ' EXPERIMENTAL SECTION Crystal Growth. Crystals of 1aÀ1c suitable for X-ray structure determination were obtained by slow cooling down of hot solutions of 1 in pure acetonitrile (1a), acetonitrile/toluene [50/50À0/100] (1b), and acetonitrile/toluene [60/40À95/5] (1c).Single-Crystal X-ray Diffraction. The intensity data were collected on a Bruker APEX II diffractometer with MoKR radiation (λ = 0.71073 A) using ωand j-scans. Reflections were corrected for background and Lorentz polarization effects. Preliminary structure

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

“…A search for structures possessing the basic calix [4]arene skeleton with the additional criteria that more than one molecule must be present in the asymmetric unit (Z' > 1) yielded a total of 332 results. Any results that featured metal binding/lower-rim bridges or possessed multiple molecules with the same conformation were discounted, leading to only a single target structure (IWESAF) [33]. This crystal structure of 5,11,17,23tetra-t-butyl-26,28-dihydroxy-25,27-dimethoxycalix [4]arene featured both the cone and partial cone conformations within the asymmetric unit.…”

Ring a bell: Disubstituted calix[4]arene as ligand for transition metal chlorides

“…The ligand alone adopts the cone conformation while in principle, many other are possible for a calix [4]arene [74,75]. Only four crystal structures of H 2 L are published, one with an empty cavity [73], two with solvent in the cavity (toluene [70] or acetonitrile [74]) and one structure in which one empty calixarene adopts a 1,2-alternate conformation and a second one a cone conformation with acetonitrile in the cavity [74].…”

“…Only four crystal structures of H 2 L are published, one with an empty cavity [73], two with solvent in the cavity (toluene [70] or acetonitrile [74]) and one structure in which one empty calixarene adopts a 1,2-alternate conformation and a second one a cone conformation with acetonitrile in the cavity [74]. In case of the cone conformation with an empty cavity, the aromatic rings opposite to each other form angles of ca.…”

Conformational diversity and dynamics of distally disubstituted calix and thiacalix[4]arenes in solution

“…Moreover, according to the X‐ray data in a solid state, these compounds adopt “irregular structure”, and it was pointed out that “the agreement between the calculated structure and the X‐ray molecular structure is satisfying, although it must be noted that the experimental structure is more irregular than the calculated structure”. Recently, the X‐ray single crystal diffraction study of the distally O‐Me disubstituted CCA acetonitrile solvate showed the unusual coexistence of two basic conformations ( cone and 1,2‐alternate ) with their relative population depending on the solvent . That is, the situation is not totally clear.…”