First total synthesis of thiocladospolide A and its C2-epimer

The first total synthesis of recently isolated thiocladospolide A (1) and its C2-epimer have been achieved in nine straightforward linear steps with 12% of overall yield. The key feature of the synthesis is the construction of the macrocyclic ring via late stage ring-closing metathesis reaction followed by alkene reduction.

Macrolides in children: judicious use, avoiding resistance and reducing adverse effects

Macrolides, a group of antibiotics molecularly characterised by a macrocyclic ring, are among the most frequently prescribed antibiotics for children. Beyond their antibacterial action, macrolides exert immunomodulatory effects. Prophylactic use is increasing. Macrolides are usually well tolerated in children, and dosing schedules are convenient. Furthermore, increasing data suggests that their prophylactic usage reduces the exacerbation frequency in children with bronchiectasis. Yet, to preserve their antibacterial action, each macrolide prescription should be judiciously considered. For prophylactic use, the indication should be regularly reviewed, and usage longer than 6 months should be avoided to reduce antimicrobial resistance.

Aqua(1,4,7,10-tetraazacyclododecane)zinc(II) bis(perchlorate)

The cationic ZnII part of aqua(1,4,7,10-tetraazacyclododecane)zinc(II) bis(perchlorate), [Zn(C8H20N4)(H2O)](ClO4)2, exhibits a slightly distorted square-pyramidal coordination environment with a water molecule in the apical position. In the crystal, the macrocyclic ring alternates between two conformations with equal occupancies. Two of the three perchlorate anions are situated about a twofold rotation axis, and one of them shows disorder of the O atoms with occupancies of 0.62 (7) and 0.38 (7). In the crystal, the complexes are connected by intermolecular hydrogen bonding via the perchlorate anions.

Ultrasonically assisted macrocyclic ring compound coatings for corrosion protection of copper in 3.5% NaCl solution

ABSTRACT: Macrocyclic ring compounds are potential corrosion inhibitors due to their high planarity, rigidity, and presence of many heteroatoms such as nitrogen, oxygen, phosphorus, and sulfur. However, their application as corrosion inhibitors has been faced with a challenge of insolubility in most organic and aqueous solvents. To overcome this challenge and to harness the untapped hydrophobic property of these compounds, this research, via ultrasonication method dispersed a macrocyclic ring compound known as free-based Phthalocyanine (Pc) to fabricate a corrosion-resistant coating on the Cu surface. The Cu samples were coated through a 24 h immersion by self-assembly method in different systems of sonicated and non-sonicated solutions of the compound in dimethyl sulfoxide (DMSO). The effect of sonication and immersion duration on the coating morphology, compactness, and consequent corrosion inhibition was analyzed. Electrochemical and surface imaging techniques revealed higher corrosion protection in 3.5% NaCl for the Pc coated Cu samples after sonication compared to the non-sonicated systems.

Exploring the dynamics of Zr-based metal–organic frameworks containing mechanically interlocked molecular shuttles

MOFs UiO-68 and PCN-57, containing triphenylene linkers, were doped with a tetracarboxylate linker that contains a [2]rotaxane molecular shuttle, and VT CP MAS 13C SSNMR was used to explore the motion of the macrocyclic ring inside the cavities.

Sensing Zn2+ in Aqueous Solution with a Fluorescent Scorpiand Macrocyclic Ligand Decorated with an Anthracene Bearing Tail

Synthesis of the new scorpiand ligand L composed of a [9]aneN3 macrocyclic ring bearing a CH2CH2NHCH2-anthracene tail is reported. L forms both cation (Zn2+) and anion (phosphate, benzoate) complexes. In addition, the zinc complexes of L bind these anions. The equilibrium constants for ligand protonation and complex formation were determined in 0.1 M NaCl aqueous solution at 298.1 ± 0.1 K by means of potentiometric (pH-metric) titrations. pH Controlled coordination/detachment of the ligand tail to Zn2+ switch on and off the fluorescence emission from the anthracene fluorophore. Accordingly, L is able to sense Zn2+ in the pH range 6–10 down to nM concentrations of the metal ion. L can efficiently sense Zn2+ even in the presence of large excess of coordinating anions, such as cyanide, sulphide, phosphate and benzoate, despite their ability to bind the metal ion.

Revision of the structure of isochaetoglobosin Db based on NMR analysis and biosynthetic consideration

Isochaetoglobosin Db is a new chaetoglobosin possessing a unique 3,4-substituted pyrrole ring isolated and named by Qiu et al., and it is different from any one of the 14 sub-types in the macrocyclic ring of chaetoglobosins classified in our previous work.

Rotaxanes comprising cyclic phenylenedioxydiacetamides and secondary mono- and bis-dialkylammonium ions: effect of macrocyclic ring size on pseudorotaxane formation

[2]Rotaxanes, stabilized through multiple and cooperative hydrogen bonding system, were synthesized from dialkylammonium ions and macrocycle possessing two phenylenedioxydiacetamide units and appropriate spacers.