The Missing Member of the Partially O-Alkylated Resorcinarene Family: Synthesis and Conformation of Methyl Tetramethoxy Resorcinarene

Abstract

An improved Lewis acid catalyzed synthesis method for methyl tetramethoxy resorcinarene is described, which produced the missing lower rim methyl derivative of this partially O-alkylated resorcinarene family. Structural characterization by means of variable temperature NMR experiments and single crystal X-ray diffraction studies furthermore revealed that the resorcinarene core adopts different conformations in the solid state and in solution.

Solid state halogen bonded networks vs. dynamic assemblies in solution: explaining N⋯X interactions of multivalent building blocks

“…Since halogen bonds are highly directional and linear in nature, 3 two different constitutional isomers of tetravalent halogen bond acceptors differing only by the position of the nitrogen atom in the pyridine rings (3-or 4-pyridyl; 1 and 2, respectively) were synthesized to control the node angles of the networks. The choice of the well-defined Cmethyl tetramethoxy resorcinarene 19 as a platform minimized the unwanted influence of the longer lower rim alkyl chains 20 on the crystal packing and on the network assembly.…”

“…Herein, we present the synthesis and solution dynamics of two multidimensional resorcinarene based halogen bond acceptors, as well as, a successful construction of two network structures stabilized by halogen bonds, in which the dimensionality and architecture was obtained by the resorcinarene core, directionality by the podand pyridine arms and cohesion by the aryl halide linkers. Solution behavior of the halogen bond donor-acceptor systems were additionally investigated in detail using NMR spectroscopic techniques and the challenges imposed by the multiple XB sites, such as several possible simultaneous interactions in solution, were resolved by computational methods using density functional theory (DFT) that provided important insight into the changes observed in the 19 F NMR spectra and into the behavior of these complex systems in solution.…”

“…In addition to the explicit solid state networks, the solution behavior between the tetravalent resorcinarenes 1 and 2 and the bi-and monovalent linkers AE in terms of halogen bonding were complemented by means of 1 H, 19 F and diffusion ordered (DOSY) NMR spectroscopy.…”

“…The linker has the total of four fluorine atoms meaning that in theory each linker could form four HBs. Therefore, 19 F NMR shifts were calculated for combinations of pure L, L+S, L+2S and L+4S which shows a shift trend toward upfield, respectively. The upward shift takes also place in experimental measurements since the chemical shifts of When a halogen bond acceptor, pyridine, is added to the model system, the linker A (L···R) shows a downfield shift compared to the average L+S shift.…”

Influence of lower rim C-methyl group on crystal forms and metal complexation of resorcinarene bis-crown-5

“…12 C 4 -symmetric tetramethoxy resorcinarenes were first synthesized by McIldowie et al, 27 and the series of different lower rim alkyl chain lengths was recently completed with a C-methyl derivative. 28 The longer alkyl chain tetramethoxy resorcinarenes (C 2 H 5 -C 11 H 23 ) have previously been used as starting materials for resorcinarene bis-and mono-crown-5 derivatives, which are synthesized by attaching one or two tetra(ethyleneglycol) bridges to the hydroxyl groups at the upper rim. 29,30 The crown ether bridged resorcinarene derivatives with a fixed boat conformation have shown a reasonable affinity towards ammonium cations, 31 33 and a helical chain, 29 especially for the metal complexes of C-ethyl resorcinarene bis-crown-5, have been observed.…”