Tetracationic Macrocycle Research Articles

Self-assembling Tetrathiafulvalene-based Rotaxanes and Catenanes

A general stepwise approach is described for the preparation of tetrathiafulvalene (TTF)-based linear and monoand dimacrocyclic compounds incorporating one or two 1,4-dioxyphenylene, 9,10-dioxyanthrylene, or 1,5- or 2,6-dioxynaphthylene units from readily available starting materials. By utilizing the π–π stacking interactions of the TTF unit with the dipyridinium dication of 1,1′-[1,4-phenylenebis (methylene)] bis-4,4′-bipyridinium bis(hexafluorophosphate), a rotaxane and two [2]catenanes were synthesized starting from the linear and monomacrocyclic compounds, respectively. From the dioxyphenylene-based dimacrocycle, three [3]pseudocatenanes (trans, cis, and a mixture of cis/trans isomers) were obtained with the trans compound as the major product. From the dioxyanthrylene dimacrocycle, only the trans-[3]pseudocatenane was obtained. Catenane products were formed quantitatively from the 1,5-dioxynaphthylene dimacrocycle in a template-directed reaction, affording a trans-[3]pseudo-catenane together with a [4]pseudocatenane (mixture of cis/trans isomers). From the 2,6-dioxynaphthylene dimacrocycle, a cis-[3]pseudocatenane was obtained as the major product and a trans-[3]pseudocatenane as the minor one. For the [3]pseudocatenanes (i.e., both the cis and trans catenanes), in which the TTF units were clamped by the tetracationic macrocycle, isomerizations were completely prevented even in the presence of trifluoroacetic acid. All new rotaxanes and catenanes were characterized by electrospray mass spectrometry, and the cis- and trans- [3]pseudocatenanes were additionally investigated by 1H NMR spectroscopy. The electrochemical and spectral properties of the rotaxane and the catenanes are reported. Catenane formation increases the redox potentials of the TTF unit. The results demonstrate the versatility of TTF as a building block in the construction of supramolecular structures.

A hydroxide inclusion complex of a methylene-bridged tetrapyrimidinium macrocycle

In the structure of 4,10,16,22-tetraamino-6,12,18,24-tetramethyl-5,11,17,23-tetraaza-1,7,13,19-tetraazoniapentacyclo[19.3.1.1 3,7 .1 9,13 .1 15,19 ]octacosa-1(25),3,5,7(26),9,11,13(27),15,17,19(28),21,23-dodecane dichloride dihydroxide octahydrate, C 24 H 32 N 12 4+ .2OH − .2Cl − .8H 2 O, the tetracationic macrocycle consists of four substituted pyrimidinium rings connected by four methylene bridges. The cation captures two hydroxide anions, one on either side of the plane through the macrocycle, via pyrimidinium ring-OH − electrostatic interactions and C-H...O hydrogen bonds, while two chloride anions are located outside the macrocycle

Towards Controllable Molecular Shuttles - 2

The design and synthesis of a molecular shuttle, in which the two components are a cyclobis(paraquat-p-phenylene) tetracationic macrocycle and a linear polyether chain intercepted by a 2,3,5-trisubstituted indole unit and a hydroquinol residue, and terminated by two 4-tritylphenyl ether functions, are described.

The Self-Assembly of a [2]Catenane

The template-directed synthesis of a [2]catenane, in which the interlocking rings are bisparaphenylene-34-crown-10 (BPP34C10) and a cyclobis (paraquat-p-phenylene) tetracationic macrocycle, is reported to occur when 4,4′ -bipyridine and 1,4-bis(bromomethyl)benzene are added to a solution of BPP34C10 in dimethylformamide. This remarkable act of self-assembly, which requires the coming together of five molecular components, is rationalised in terms of the mutual recognition properties displayed by the individual parts of a compound undergoing construction in a modular manner.

A Novel Type of Cationic Host Molecules with π‐Acceptor Properties

Surprisingly, the template effect of a hydrocarbon has been detected for the first time: the yield in the one-pot synthesis of the tetracationic macrocycle 1c is raised from 3–5% to 16% when excess phenanthrene is present. The new phane-like tetracations 1a-c and 2a-c act as π-acceptor host compounds and take up arenes as π-donors in their cavities in a sandwich-like manner.