Nat cam tube
The open cylindrical cavity of 1 is fully girded by the polyaromatic anthracene panels with inner diagonal distances of 0.9–1.1 nm.The tubular structure provides a well-defined hydrophobic nanospace and hydrophilic pyridinium and methoxyethoxy groups so that we examined the host capability of the amphiphilic tube 1 for long hydrocarbons in aqueous solutions.) but shows selectivity for a multiply branched alkane over nonbranched alkanes.Electrospray ionization time-of-flight mass spectrometry (ESI-TOF MS) analysis confirmed the formation of 1 with a molecular weight of 1,532.67 Da: a prominent signal was observed at m/z=730.9, assigned to the [1−2Cl species.The structure of 1 was unambiguously confirmed by X-ray crystallographic analysis.1b) through hydrophobic aromatic–aliphatic and/or aromatic–olefinic interactions in 1:1 water/methanol solutions. 2a) with two embedded anthracene panels to design molecular tube 1. 26) were reacted in 1-propanol at 85 °C over 7 days, molecular tube 1 formed and was isolated as a yellow solid (9% yield).The rigidly bent conformation of 2b facilitates the formation of supramolecular assemblies such as (i) capsular structures through noncovalent, coordinative transition-metal linkages) of 2a were found at considerable downfield (8.64–9.87 p.p.m.), indicating the formation of N-phenylpyridinium units (Fig. The signals (Δδ=−0.4 p.p.m.) indicate a tubular structure, in which the interior aromatic protons are shielded by the adjacent anthracene panels.Herein we report the synthesis and host properties of molecular tube 1 which presents a hydrophobic cavity encircled by polyaromatic anthracene panels (Fig. The tube is obtained by the transition-metal-free cross-coupling reaction of end-functionalized, bent compounds with two embedded anthracene rings.The girded cylindrical cavity (~1 nm in diameter and length) of tube 1 selectively binds long hydrocarbons with branched methyl groups and/or unsaturated moieties, such as 2,2,4,4,6,8,8-heptamethylnonane (4a), nervonic acid methyl ester (5a), squalene (6a) and coenzyme Q4 (6c) (Fig.
The exclusive binding of 5a by the tube (H NMR spectrum after the combination of 1 and 5b in a water/methanol solution.Therefore, the tube strictly recognized the existence of a single carbon–carbon double bond within the long hydrocarbon ester, presumably through polyaromatic–olefinic host–guest interactions.Tube 1 can bind both cis- and trans-isomers of unsaturated fatty acid esters.When tube 1, squalene (6a) and squalane (6b), which is the fully hydrogenated squalene, were combined in a 1:1 D99%) at room temperature to afford a 1·6a complex (24% yield), as confirmed by NMR analysis (Fig. The size and shape of 6b are comparable to that of 6a, but surprisingly 6b was not bound at all by 1 even in the absence of 6a. and −0.22 p.p.m., respectively, with huge upfield shifts (Δδ=2.2 p.p.m.), indicating tight contacts between the central part of 6a and the anthracene frameworks of 1.The NOESY NMR spectrum showed several sets of correlation signals between the tube and the bound guest (for example, H).