Self-assembled cages and capsules using cyclotriveratrylene-type scaffolds

Pyramidal molecular hosts related to cyclotriveratrylene (CTV) form selfassembled cages including organic cages, hydrogen-bonded cages and metallo-cages. The latter include M3L2, M4L4, M6L8 and M12L8 assemblies including topologically complicated structures. Metallo-cages may show ligand-exchange and/or homochiral sorting of the C3-symmetric CTV-analogue ligands. Cages also occur within coordination networks

Fully Collapsed Imploded Cryptophanes in Solution and in the Solid State

Cryptophanes with flexible linkers derived from (±)‐tris‐(4‐formyl‐phenyl)‐cyclotriguaiacylene with either bisoxydi(ethylamine) or bis(aminopropyl)ether were isolated as single crystals, the crystal structures of which showed the proposed, but previously uncharacterised, out‐in conformation, in which both cyclotriguaiacylene fragments adopt a crown conformation with one crown sitting inside the other. The usual cage‐like out‐out conformation of the cryptophanes was observed when crystals were dissolved upon heating, and the molecules collapsed back to the out‐in isomers over time. In contrast, a cryptophane also derived from (±)‐tris‐(4‐formyl‐phenyl)‐cyclotriguaiacylene but with rigid dibenzalhydrazine linkers was isolated as the more usual out‐out isomer

Self-Assembly and Host–Guest Interactions of Pd3L2 Metallo-cryptophanes with Photoisomerizable Ligands

New photoswitchable pyridyl-azo-phenyl-decorated tripodal host ligands (Laz) that belong to the cyclotriveratrylene family have been synthesized, and their photoswitching behavior and crystal structures determined. The latter includes a remarkable 7-fold Borromean-weave entanglement of π–π stacked layers. Trigonal bipyramidal {[Pd(en)]3(Laz)2}6+ metallo-cryptophanes (en = ethylenediamine) were formed from these and a previously known pyridyl-azo-phenyl-decorated tripodal host ligand. These coordination cages dissociate at low concentrations and are less robust to photoswitching of the Laz ligands than were previously reported Ir(III)-linked metallo-cryptophanes with similar ligands, reflecting the greater lability of the Pd–N bonds. The {[Pd(en)]3(Laz)2}6+ cages all act as hosts, binding octyl sulfate anions, or N-[2-(dimethylamino)ethyl]-1,8-naphthalimide in a dimethyl sulfoxide solution

Tris-N-alkylpyridinium-functionalised cyclotriguaiacylene hosts as axles in branched [4]pseudorotaxane formation

A series of [4]pseudorotaxanes composed of three-way axle threads based on the cyclotriguaiacylene family of crown-shaped cavitands and three threaded macrocyclic components has been achieved. These exploit the strong affinity for electron-poor alkyl-pyridinium units to reside within the electron-rich cavity of macrocycles, in this case dimethoxypillar[5]arene (DMP). The branched [4]pseudorotaxane= assemblies {(DMP)3∙L}3+,where L = N-alkylated derivatives of the host molecule (±)-tris-(isonicotinoyl)cyclotriguaiacylene, were characterised by NMR spectroscopy and mass spectrometry, and an energy-minimised structure of {(DMP)3∙(tris-(N-propyl-isonicotinoyl)cyclotriguaiacylene)}3+ was calculated. Crystal structures of N-ethyl-isonicotinoyl)cyclotriguaiacylene hexafluorophosphate and N-propyl-isonicotinoyl)cyclotriguaiacylene hexafluorophosphate each show ‘hand-shake’ self-inclusion motifs occurring between the individual cavitands

An Area‐Specific, International Community‐Led Approach to Understanding and Addressing Equality, Diversity, and Inclusion Issues within Supramolecular Chemistry

Diversity, equality, and inclusion (DEI/EDI) are pressing issues in chemistry and the natural sciences. In this Essay we share how an area‐specific approach is “calling in” the community so that it can act to address EDI issues, and support those who are marginalised. Women In Supramolecular Chemistry (WISC) is an international network that aims to support equality, diversity, and inclusion within supramolecular chemistry. WISC has taken a field‐specific approach using qualitative research methods with scientists to identify the support that is needed and the problems the supramolecular community needs to address. Herein, we present survey data from the community which highlight the barriers that are faced by those who take career breaks for any reason, a common example is maternity leave, and the importance of mentoring to aid progression post‐PhD. In conclusion, we set out an interdisciplinary and creative approach to addressing EDI issues within supramolecular chemistry

AMP-Activated Kinase AMPK Is Expressed in Boar Spermatozoa and Regulates Motility

The main functions of spermatozoa required for fertilization are dependent on the energy status and metabolism. AMP-activated kinase, AMPK, acts a sensor and regulator of cell metabolism. As AMPK studies have been focused on somatic cells, our aim was to investigate the expression of AMPK protein in spermatozoa and its possible role in regulating motility. Spermatozoa from boar ejaculates were isolated and incubated under different conditions (38,5°C or 17°C, basal medium TBM or medium with Ca2+ and bicarbonate TCM, time from 1–24 hours) in presence or absence of AMPK inhibitor, compound C (CC, 30 µM). Western blotting reveals that AMPK is expressed in boar spermatozoa at relatively higher levels than in somatic cells. AMPK phosphorylation (activation) in spermatozoa is temperature-dependent, as it is undetectable at semen preservation temperature (17°C) and increases at 38,5°C in a time-dependent manner. AMPK phosphorylation is independent of the presence of Ca2+ and/or bicarbonate in the medium. We confirm that CC effectively blocks AMPK phosphorylation in boar spermatozoa. Analysis of spermatozoa motility by CASA shows that CC treatment either in TBM or in TCM causes a significant reduction of any spermatozoa motility parameter in a time-dependent manner. Thus, AMPK inhibition significantly decreases the percentages of motile and rapid spermatozoa, significantly reduces spermatozoa velocities VAP, VCL and affects other motility parameters and coefficients. CC treatment does not cause additional side effects in spermatozoa that might lead to a lower viability even at 24 h incubation. Our results show that AMPK is expressed in spermatozoa at high levels and is phosphorylated under physiological conditions. Moreover, our study suggests that AMPK regulates a relevant function of spermatozoa, motility, which is essential for their ultimate role of fertilization

The LKB1-salt-inducible kinase pathway functions as a key gluconeogenic suppressor in the liver

LKB1 is a master kinase that regulates metabolism and growth through adenosine monophosphate-activated protein kinase (AMPK) and 12 other closely related kinases. Liver-specific ablation of LKB1 causes increased glucose production in hepatocytes in vitro and hyperglycaemia in fasting mice in vivo. Here we report that the salt-inducible kinases (SIK1, 2 and 3), members of the AMPK-related kinase family, play a key role as gluconeogenic suppressors downstream of LKB1 in the liver. The selective SIK inhibitor HG-9-91-01 promotes dephosphorylation of transcriptional co-activators CRTC2/3 resulting in enhanced gluconeogenic gene expression and glucose production in hepatocytes, an effect that is abolished when an HG-9-91-01-insensitive mutant SIK is introduced or LKB1 is ablated. Although SIK2 was proposed as a key regulator of insulin-mediated suppression of gluconeogenesis, we provide genetic evidence that liver-specific ablation of SIK2 alone has no effect on gluconeogenesis and insulin does not modulate SIK2 phosphorylation or activity. Collectively, we demonstrate that the LKB1-SIK pathway functions as a key gluconeogenic gatekeeper in the liver

Metformin mitigates the impaired development of skeletal muscle in the offspring of obese mice

Background: Maternal obesity is linked with offspring obesity and type 2 diabetes. Skeletal muscle (SM) insulin resistance is central to the development of diabetes. Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is inhibited in SM of fetuses born to obese mothers

Molecular crowding defines a common origin for the Warburg effect in proliferating cells and the lactate threshold in muscle physiology

Aerobic glycolysis is a seemingly wasteful mode of ATP production that is seen both in rapidly proliferating mammalian cells and highly active contracting muscles, but whether there is a common origin for its presence in these widely different systems is unknown. To study this issue, here we develop a model of human central metabolism that incorporates a solvent capacity constraint of metabolic enzymes and mitochondria, accounting for their occupied volume densities, while assuming glucose and/or fatty acid utilization. The model demonstrates that activation of aerobic glycolysis is favored above a threshold metabolic rate in both rapidly proliferating cells and heavily contracting muscles, because it provides higher ATP yield per volume density than mitochondrial oxidative phosphorylation. In the case of muscle physiology, the model also predicts that before the lactate switch, fatty acid oxidation increases, reaches a maximum, and then decreases to zero with concomitant increase in glucose utilization, in agreement with the empirical evidence. These results are further corroborated by a larger scale model, including biosynthesis of major cell biomass components. The larger scale model also predicts that in proliferating cells the lactate switch is accompanied by activation of glutaminolysis, another distinctive feature of the Warburg effect. In conclusion, intracellular molecular crowding is a fundamental constraint for cell metabolism in both rapidly proliferating- and non-proliferating cells with high metabolic demand. Addition of this constraint to metabolic flux balance models can explain several observations of mammalian cell metabolism under steady state conditions

Metallo-cryptophane cages from cis-linked and trans-linked strategies

Trigonal bipyramidal metallo-cage species [Pd₃(dppp)₃(L)₂]∙6OTf (where dppp = bis(diphenylphosphino)propane, OTf = triflate and L is tris(iso-nicotinoyl)cyclotriguaiacylene (L1) or tris(fluoro-iso-nicotinoyl)cyclotriguaiacylene (FL1)) have been characterised in solution to exist predominantly as the anti-isomers. The crystal structure of [Pd₃(dppp)₃(FL1)₂]∙6OTf, however, was found to be the achiral syn-isomer. The complex [Pd₃Cl₃(L2)₂] (where L2 = tris(methylbenzimidazolyl)cyclotriguaiacylene) is a trans-linked M₃L₂ cage, observed by mass spectrometry and in the solid state as the anti-isomer. Ligand L2 also forms a 1:1 co-crystal with cyclotriguaiacylene