Chiral self-sorting process in the self-assembly of homochiral coordination cages from axially chiral ligands

Abstract

Chiral self-sorting is a phenomenon wherein racemic components are spontaneously sorted into homo-or heterochiral molecular assemblies through chiral discrimination between the components. Chiral self-sorting may be related to biological molecular systems where chiral biomolecules are concerned, but the detail of this sorting process has been unclear. Here we show the chiral self-sorting process in the formation of a homochiral Pd 2 L 4 coordination cage from a racemic mixture of a binaphthol-based ditopic ligand by quantitative analysis of self-assembly process (QASAP). The self-assembly of the cage mainly takes place through two pathways that branch off from the intermolecular reaction of mononuclear complexes. Even though the homochiral cages are thermodynamically the most stable, heterochiral intermediates were preferentially produced at first under kinetic control, which were eventually converted into the homochiral cages. Our results reveal complicated pathways in chiral self-sorting.

Self-assembly process of a quadruply interlocked palladium cage

“…This is due to the removal of the Py* molecule, whose coordination ability is weaker than 1, during the ionization. Similar results have often been obtained in other Pd(II)-linked coordination self-assemblies [40][41][42] . The result that the signals for Pd 4 1 8 were observed instead of that for Pd 4 1 8 Py* can be interpreted in the same way.…”

Chiral Resolution of Spin‐Crossover Active Iron(II) [2x2] Grid Complexes

“…Chiral self‐sorting is a phenomenon where racemic components are spontaneously sorted into homo‐ or hetero‐chiral molecular assemblies through chiral discrimination between the components. [ 55 , 56 , 57 ] The presence of some pure diastereomeric crystals from the first crystallization step could have helped by taking on the role of the seed crystal and undergo preferential crystallization. [58] This helped to improve the diastereoselectivity, as evidenced by CD measurements.…”

“…[50,51] Mössbauer spectroscopy 57 Fe Mössbauer spectroscopy is also another valuable tool for accessing the spin and charge state of the Fe atoms. [52] So, in order to study the spin states at various temperatures, Mössbauer spectra were measured for the 57 Fe enriched Λ S and Δ R enantiomeric complexes at 77 K and 300 K temperature. The parameters obtained are compiled in the Table 2.…”

“…[49] On the other hand, T(LIESST) temperatures are very similar to each other and correspond to high T 1/2 temper-ature of thermal SCO, which agrees with the "inverse energy gap law," which states T(LIESST) is inversely proportional to T 1/ 2 . [50,51] Mössbauer spectroscopy 57 Fe Mössbauer spectroscopy is also another valuable tool for accessing the spin and charge state of the Fe atoms. [52] So, in order to study the spin states at various temperatures, Mössbauer spectra were measured for the 57 Fe enriched Λ S and Δ R enantiomeric complexes at 77 K and 300 K temperature.…”

Nonconventional driving force for selective oxidative C–C coupling reaction due to concurrent and curious formation of Ag0

“…In this observation we saw a potential in conducting a pair of redox reaction involving Ag + to Ag 0 and phenol to bisphenol as coupled reactions. This prompted us to carry out Tollens' test on β -naphthol, a common phenol employed for bisphenol formation, as the product bisnaphthol itself finds importance in asymmetric synthesis and material science 5 , 6 . The reaction gave a positive result, meaning formation of a silver mirror on the walls of test tube.…”