Synthesis and stability of 2-(1,1-difluoroalkyl) thiophenes and related 1,1-difluoroalkyl benzenes: fluorinated building blocks for liquid crystal synthesis

Tetrahedron ◽  
2001 ◽  
Vol 57 (27) ◽  
pp. 5757-5767 ◽  
Author(s):  
Andre A. Kiryanov ◽  
Alexander J. Seed ◽  
Paul Sampson
2017 ◽  
Author(s):  
Niamh Mac Fhionnlaoich ◽  
Stephen Schrettl ◽  
Nicholas B. Tito ◽  
Ye Yang ◽  
Malavika Nair ◽  
...  

The arrangement of nanoscale building blocks into patterns with microscale periodicity is challenging to achieve via self-assembly processes. Here, we report on the phase transition-driven collective assembly of gold nanoparticles in a thermotropic liquid crystal. A temperature-induced transition from the isotropic to the nematic phase leads to the assembly of individual nanometre-sized particles into arrays of micrometre-sized aggregates, whose size and characteristic spacing can be tuned by varying the cooling rate. This fully reversible process offers hierarchical control over structural order on the molecular, nanoscopic, and microscopic level and is an interesting model system for the programmable patterning of nanocomposites with access to micrometre-sized periodicities.


2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Patricia Calero ◽  
Daniel C. Volke ◽  
Phillip T. Lowe ◽  
Charlotte H. Gotfredsen ◽  
David O’Hagan ◽  
...  

Abstract Fluorine is a key element in the synthesis of molecules broadly used in medicine, agriculture and materials. Addition of fluorine to organic structures represents a unique strategy for tuning molecular properties, yet this atom is rarely found in Nature and approaches to integrate fluorometabolites into the biochemistry of living cells are scarce. In this work, synthetic gene circuits for organofluorine biosynthesis are implemented in the platform bacterium Pseudomonas putida. By harnessing fluoride-responsive riboswitches and the orthogonal T7 RNA polymerase, biochemical reactions needed for in vivo biofluorination are wired to the presence of fluoride (i.e. circumventing the need of feeding expensive additives). Biosynthesis of fluoronucleotides and fluorosugars in engineered P. putida is demonstrated with mineral fluoride both as only fluorine source (i.e. substrate of the pathway) and as inducer of the synthetic circuit. This approach expands the chemical landscape of cell factories by providing alternative biosynthetic strategies towards fluorinated building-blocks.


2020 ◽  
Vol 117 (12) ◽  
pp. 6437-6445 ◽  
Author(s):  
Hayley R. O. Sohn ◽  
Ivan I. Smalyukh

Malleability of metals is an example of how the dynamics of defects like dislocations induced by external stresses alters material properties and enables technological applications. However, these defects move merely to comply with the mechanical forces applied on macroscopic scales, whereas the molecular and atomic building blocks behave like rigid particles. Here, we demonstrate how motions of crystallites and the defects between them can arise within the soft matter medium in an oscillating electric field applied to a chiral liquid crystal with polycrystalline quasi-hexagonal arrangements of self-assembled topological solitons called “torons.” Periodic oscillations of electric field applied perpendicular to the plane of hexagonal lattices prompt repetitive shear-like deformations of the solitons, which synchronize the electrically powered self-shearing directions. The temporal evolution of deformations upon turning voltage on and off is not invariant upon reversal of time, prompting lateral translations of the crystallites of torons within quasi-hexagonal periodically deformed lattices. We probe how these motions depend on voltage and frequency of oscillating field applied in an experimental geometry resembling that of liquid crystal displays. We study the interrelations between synchronized deformations of the soft solitonic particles and their arrays, and the ensuing dynamics and giant number fluctuations mediated by motions of crystallites, five–seven defects pairs, and grain boundaries in the orderly organizations of solitons. We discuss how our findings may lead to technological and fundamental science applications of dynamic self-assemblies of topologically protected but highly deformable particle-like solitons.


1999 ◽  
Vol 93 (1) ◽  
pp. 27-31 ◽  
Author(s):  
Ireneusz Nowak ◽  
Lillian M. Rogers ◽  
Robin D. Rogers ◽  
Joseph S. Thrashe

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