Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

• -responsive switchable tweezers are based on an H-bonding motif that can establish recognition interactions with the anionic species. One of the first examples was developed by Sessler, Jeppesen, and co-workers with a calix[4]pyrrole switching unit [68]. Calix[4]pyrrole tweezers 33 are functionalized by four

• -conformation calix[4]pyrrole and the electron-donating nature of TTFs allow the complexation of electron-poor C60 guests [71]. A 2:1 complexation of C60 by TTF-functionalized calix[4]pyrrole 33 was observed for the Cl− bound cone conformation with each calix[4]pyrrole entrapping C60 on one side. The complex

Tying a knot between crown ethers and porphyrins

• Maksym Matviyishyn and
• Bartosz Szyszko

Beilstein J. Org. Chem. 2023, 19, 1630–1650, doi:10.3762/bjoc.19.120

• slightly enhanced upon complexation. Crowned calixpyrroles In 2008, Sessler and co-workers synthesised an ion-pair receptor incorporating a calix[4]pyrrole framework functionalised with the crown ether units attached through meso-aryl groups (Scheme 1) [101]. The system comprised a crown-6-calix[4]arene

• -capped calix[4]pyrrole cavitand 4. The heteroditopic receptor had multiple binding sites, proving efficient in encapsulating a CsF ion pair. The calix[4]arene-crown-6-capped pocket was exploited as an excellent binding site for the Cs+ cation, whereas the calix[4]pyrrole was aligned to trap the fluoride

• separation between the cation and anion. Sessler and co-workers introduced a similar ion-pair receptor, in which the calix[4]arene-strapped calix[4]pyrrole 5 demonstrated an additional binding mode of CsF (Figure 5). The binding constant Ka = 1.3·104 M−1 in CHCl3/MeOH 9:1 was reported [101][102]. This

Supramolecular approaches to mediate chemical reactivity

• Pablo Ballester,
• Qi-Qiang Wang and
• Carmine Gaeta

Beilstein J. Org. Chem. 2022, 18, 1463–1465, doi:10.3762/bjoc.18.152

• of novel supramolecular catalysts. In their contribution Wang and co-workers [17] reported an interesting example of chalcogen bonding catalysis approach for the synthesis of calix[4]pyrrole macrocycles. The Se···O=C chalcogen bonding interactions between a selenide-based catalyst and the carbonyl

• -substrate catalyzed the macrocyclization with pyrrole. Interestingly, only 5 mol % of catalyst loadings were necessary in order to promote the condensation processes, and calix[4]pyrrole derivatives were obtained in moderate to high yields. Mild reaction conditions were employed, thus highlighting the

A Se···O bonding catalysis approach to the synthesis of calix[4]pyrroles

• Qingzhe Tong,
• Zhiguo Zhao and
• Yao Wang

Beilstein J. Org. Chem. 2022, 18, 325–330, doi:10.3762/bjoc.18.36

• ]pyrrole derivatives. The Se···O bonding interactions between selenide catalysts and ketones gave rise to the catalytic activity in the condensation reactions between pyrrole and ketones, leading to the generation of calix[4]pyrrole derivatives in moderate to high yields. This chalcogen bonding catalysis

• . Keywords: calix[4]pyrrole; chalcogen bonding; ketones; Se···O bonding interactions; supramolecular catalysis; Introduction Noncovalent catalysis has been established as one of the fundamental concepts in organic synthesis that enables achieving numerous chemical transformations [1]. Among these

• ]. Despite these significant advances, catalysis with chalcogen bonding interactions is still in its infancy and the development of new types of reactions is highly desirable. Calix[4]pyrrole derivatives have been widely used as transition metal ligands and functional materials [50][51][52][53]. Thus far

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

• Lena Reinke,
• Julia Bartl,
• Marcus Koch and
• Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

• . AuNP-based probes for inorganic anions, for example, can serve to monitor the water quality [14][15]. An example is the probe for halides that was described by the Sessler group. It comprised AuNPs with immobilized calix[4]pyrrole residues that are known to interact with chloride and fluoride. The

Design, synthesis and application of carbazole macrocycles in anion sensors

• Alo Rüütel,
• Ville Yrjänä,
• Sandip A. Kadam,
• Indrek Saar,
• Mihkel Ilisson,
• Astrid Darnell,
• Kristjan Haav,
• Tõiv Haljasorg,
• Lauri Toom,
• Johan Bobacka and
• Ivo Leito

Beilstein J. Org. Chem. 2020, 16, 1901–1914, doi:10.3762/bjoc.16.157

• superstructures [11]. The rings should be of remarkable size for accommodating even small anions, such as acetate. In many cases the receptor is formally a macrocycle, but the anion is bound on its “surface”, not inside the ring [10][12]. A well-known example is the calix[4]pyrrole family, which emerged as an

Star-shaped tetrathiafulvalene oligomers towards the construction of conducting supramolecular assembly

• Masahiko Iyoda and
• Masashi Hasegawa

Beilstein J. Org. Chem. 2015, 11, 1596–1613, doi:10.3762/bjoc.11.175

• species. Among radially expanded TTFs, Jeppesen, Becher, Nielsen, Sessler, and co-workers reported TTF-calix[4]pyrrole 3 as a valuable supramolecular receptor, and 3 easily incorporated 1,3,5-trinitrobenzene (TNB) in the cavity to form 4 (3:TNB = 1:2) (Figure 2) [41][42]. Furthermore, in the presence of

• halide ions, 3 formed the C60 complex 5, in which C60 was bound within the bowl-like cup of the TTF-calix[4]pyrrole core in a ball-and-socket binding mode [43]. Recently, the C3-symmetric compounds 6a,b incorporating three TTF residues were reported by Amabilino, Avarvari, and co-workers (Figure 3) [21

• nanoobjects find functions in a variety of mass use devices. Radially expanded TTF oligomers 1 and 2a,b. TTF-calix[4]pyrrole 3 and its TNT and C60 complexes 4 and 5. C3-symmetric TTF derivatives 6a,b and 7a–c. Radially expanded TTF derivatives 8, 9, and 10a,b. Amphiphilic TTFs 11–14 and 15a,b. TTF dimers

The first direct synthesis of β-unsubstituted meso- decamethylcalix[5]pyrrole

• Luis Chacón-García,
• Lizbeth Chávez,
• Denisse R. Cacho and
• Josue Altamirano-Hernández

Beilstein J. Org. Chem. 2009, 5, No. 2, doi:10.3762/bjoc.5.2

• ketone is that the five heterocycle system is unstable: it opens and loses a pyrrole-isopropyl fragment to give the calix[4]pyrrole [8][10]. In a recent report we described the synthesis of calix[4]pyrroles via the direct condensation of pyrrole with a series of ketones in the presence of a bismuth salt