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A method is provided for using twisted acenes, and more particularly to configurationally stable twisted acenes that are imbedded into the structure of [7]helicene at the fulcrum ring to form useable material structures. The helicene propa- gates its chiral nature into the acene, while acting as a locking mechanism to thermal racemization. These doubly- helical compounds are part of a new homologous series of polycyclic aromatic hydrocarbons, namely the [7]helitwis- tacenes. Such [7]helitwistacenes have utility as materials suitable for forming a circularly polarized organic light emitting diode (CP-OLED) for direct emission of circularly polarized (CP) light for the fabrication of high efficiency electronic displays. 

Although catenanes comprising two ring-shaped components can be made in large quantities by templation, the preparation of three-dimensional (3D) catenanes with cage-shaped components is still in its infancy. Here, we report the design and syntheses of two 3D catenanes by a sequence of S N 2 reactions in one pot. The resulting triply mechanically interlocked molecules were fully characterized in both the solution and solid states. Mechanistic studies have revealed that a suit[3]ane, which contains a threefold symmetric cage component as the suit and a tribromide component as the body, is formed at elevated temperatures. This suit[3]ane was identified as the key reactive intermediate for the selective formation of the two 3D catenanes which do not represent thermodynamic minima. We foresee a future in which this particular synthetic strategy guides the rational design and production of mechanically interlocked molecules under kinetic control. 

Hybrid polyaromatic hydrocarbons (PAHs) consisting of helicene and acene domains, referred to as [7]heli‐D‐acenes, are introduced as scaffolds to generate enantiopure twisted acenes (heli‐twistacenes) by a torque, lock, and propagate (TLP) approach. Computational methods with and without dispersion corrections were used to explore the structural and electronic features of these PAHs and to explore the possible formation of twistomers that might complicate reaction mixtures. Syntheses of unsubstituted and disubstituted members of the [7]heli‐D‐acene series confirmed the viability of the TLP approach, and together with the computational results, provided proof‐of‐concept of this new approach as a viable means to generate enantiopure twisted‐acenes. The X‐ray structures, absorption, fluorescence, phosphorescence, and CD spectra of these first generation heli‐acenes are compared to the structure and photophysical properties of pentacene and [7]helicene. A high barrier for the enantio‐enriched M enantiomer of 19,24‐dicyano[7]heli‐D‐anthracene verified its configurational stability at room temperature.

 

Iron is essential to life, but surprisingly little is known about how iron is managed in nonvertebrate animals. In mammals, the well‐characterizedtransferrinsbind iron and are involved in iron transport or immunity, whereas other members of thetransferrinfamily do not have a role in iron homeostasis. In insects, the functions oftransferrinsare still poorly understood. The goals of this project were to identify thetransferringenes in a diverse set of insect species, resolve the evolutionary relationships among these genes, and predict which of thetransferrinsare likely to have a role in iron homeostasis. Our phylogenetic analysis oftransferrinsfrom 16 orders of insects and two orders of noninsect hexapods demonstrated that there are four orthologous groups of insecttransferrins. Our analysis suggests thattransferrin 2arose prior to the origin of insects, andtransferrins 1,3, and4arose early in insect evolution. Primary sequence analysis of each of the insecttransferrinswas used to predict signal peptides, carboxyl‐terminal transmembrane regions, GPI‐anchors, and iron binding. Based on this analysis, we suggest thattransferrins 2,3, and4are unlikely to play a major role in iron homeostasis. In contrast, thetransferrin 1orthologs are predicted to be secreted, soluble, iron‐binding proteins. We conclude thattransferrin 1orthologs are the most likely to play an important role in iron homeostasis. Interestingly, it appears that the louse, aphid, and thrips lineages have lost thetransferrin 1gene and, thus, have evolved to manage iron withouttransferrins.

 

Transferrins function in iron sequestration and iron transport by binding iron tightly and reversibly. Vertebrate transferrins coordinate iron through interactions with two tyrosines, an aspartate, a histidine, and a carbonate anion, and conformational changes that occur upon iron binding and release have been described. Much less is known about the structure and functions of insect transferrin‐1 (Tsf1), which is present in hemolymph and influences iron homeostasis mostly by unknown mechanisms. Amino acid sequence and biochemical analyses have suggested that iron coordination by Tsf1 differs from that of the vertebrate transferrins. Here we report the first crystal structure (2.05 Å resolution) of an insect transferrin.Manduca sexta(MsTsf1) in the holo form exhibits a bilobal fold similar to that of vertebrate transferrins, but its carboxyl‐lobe adopts a novel orientation and contacts with the amino‐lobe. The structure revealed coordination of a single Fe³⁺ion in the amino‐lobe through Tyr90, Tyr204, and two carbonate anions. One carbonate anion is buried near the ferric ion and is coordinated by four residues, whereas the other carbonate anion is solvent exposed and coordinated by Asn121. Notably, these residues are highly conserved in Tsf1 orthologs. Docking analysis suggested that the solvent exposed carbonate position is capable of binding alternative anions. These findings provide a structural basis for understanding Tsf1 function in iron sequestration and transport in insects as well as insight into the similarities and differences in iron homeostasis between insects and humans.