0000000000073393
AUTHOR
Minna Luostarinen
Interaction of aminomethylated resorcinarenes with rhodamine B
The interaction of aminomethylated resorcinarenes with a red xanthene dye, rhodamine B, was investigated in chloroform, methanol and chloroform–methanol solutions using UV-vis, NMR and fluorescence spectroscopy. Aminomethylated resorcinarenes 1 and 2 shift the rhodamine B equilibrium from the zwitterion to the lactone form unlike reference compounds 3 and 4, which do not contain tertiary amino groups at the upper rim, giving an example of how supramolecular hosts can influence the equilibrium of rhodamine B isomers.
Hydrogen bond-stabilised N-alkylammonium resorcinarene halide cavitands
A family of hydrogen bond-stabilised N-alkylammonium resorcinarene chloride and bromide cavitands were synthesised and characterised with 1H NMR and ESI mass spectrometry. The seven compounds exhibit interestingly either self-inclusion or guest complexation in the solid state evidenced by single crystal X-ray diffraction. The four dimers show self-inclusion of the upper rim propyl chains and consist of two hydrogen-bonded resorcinarene tetracations and six halide anions, while the remaining two halide anions are located in between the dimers linking them via hydrogen bonding. Small solvent molecules such as dichloromethane, methanol, n-butanol or chloroform are complexed into the resorcinar…
Ethyl Pyrogallarene and Pyrogallarene: Synthesis, Structural Analysis and Derivatization
In the acid-catalyzed synthesis of ethyl pyrogall[4]arene, a novel hexamer, ethyl pyrogall[6] arene, is obtained as a readily isolable minor product. Pyrogall[6]arene can be isolated from the reaction mixture in three different ways yielding the hexamer in different forms and stabilities. Crystallization from DMSO and then recrystallization from acetone gives a stable crystalline solid, recrystallization directly from acetone yields an unstable white powder, while direct recrystallization from THF gives a stable white powder. Both pyrogall[4]arene and pyrogall[6]arene crystallize readily with DMSO filling the voids in the crystal lattice. Co-crystallization studies of the hexamer isolated b…
Derivatisation of Pyrogallarenes
Derivatisation of upper-rim hydroxy groups of pyrogallarenes produced completely acylated and tosylated pyrogallarene derivatives. Mesitylation of pyrogallarene, however, resulted in a regioselective derivatisation of hydroxy groups, i.e. eight OH groups out of 12 were mesitylated. Crystal structures of the synthesised pyrogallarene derivatives indicate that completely substituted pyrogallarenes exist in a distorted crown conformation despite of the lack of stabilising intramolecular hydrogen bonds. In contrast, the partially substituted pyrogallarene adopts a boat conformation and has an open cavity for the inclusion of small guest molecules. © Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinh…
Partial aminomethylation of resorcarenes.
Aminomethylation of resorcarenes at the wider rim with bulky diisopropylamine and formaline leads to trisubstituted derivatives. Analogous reaction with C(2v)-symmetrical resorcarene tetratosylate gives the monoaminomethylated compound. Further reactions of remaining unsubstituted resorcinol rings result in new resorcarene derivatives. [reaction: see text]
Regioselective acylation of aminoresorcinarenes
Abstract The acid catalyzed hydrolytic cleavage of the oxazine rings in the readily available tetraoxazine derivatives of resorcinarenes results in tetraaminoresorcinarenes. A similar process applied to C2-symmetrical bisoxazine resorcinarene tetratosylates affords C2v-symmetrical resorcinarenediamines. The mild acylation of these resorcinareneamines with BOC-anhydride or para-nitrophenyl ester proceeds selectively at the nitrogen atoms without affecting the hydroxyl groups. Most of the resulting resorcinareneamides are thus obtained in preparative yields and can be easily purified by simple crystallizations. In the crystalline state the compounds obtained are found to bind chloride anions …
Complexation of C-methyl pyrogallarene with small quaternary and tertiary alkyl ammonium cations
Complexation properties of pyrogallarene 1 towards small quaternary and tertiary alkyl ammonium cations were studied in gas phase, solution and in solid state. In gas phase both dimeric capsules and monomeric 1 : 1 complexes of all cations 2a+–d+ are detected but only in the case of 2a+ is the abundance of the capsule form higher than the monomeric 1 : 1 complex. A similar trend is observed in NMR experiments, which reveal a favourable dimeric complex for 2a+ and a weaker dimeric complex for 2b+ but only monomeric complexes for 2c+ and 2d+. Also in solid state, 2a+ and 2b+ form capsules when crystallized from MeOH while 2c+ and 2d+ form dimeric 1 : 1 complexes. As a reference, hetero-confor…
Resorcinarene-based ATRP initiators for star polymers
Two novel multifunctional initiators for atom transfer radical polymeriza- tion (ATRP) were synthesized by derivatization of tetraethylresorcinarene. The deri- vatization induced a change in the conformation of the resorcinarene ring, which was confirmed by NMR spectroscopy. The initiators were used in ATRP of tert-butyl acrylate and methyl methacrylate, producing star polymers with controlled molar masses and low polydispersities. Instead of the expected star polymers with eight arms, polymers with four arms were obtained. Conformational studies on the initiators by rotating- frame nuclear Overhauser and exchange spectroscopy NMR and molecular modeling suggested that of eight initiator fun…