Co-Crystallization of Achiral Components into Chiral Network by Supramolecular Interactions: Coordination Complexes – Organic Radical

Abstract

Co-crystallization is an important aspect of crystal engineering that has found major applications in the development and manufacture of pharmaceutical drugs but is rarely invoked in the development of magnetic materials. Co-crystals have been serendipitously obtained instead of the usual coordination polymers from the organic radical, 2,2-pentamethylene-4,4,5,5tetramethylimidazolidine-l-oxyl, and coordination complexes, cis-M II (hfac) 2 (H 2 O) 2 , where M = Co or Mn and hfac = hexafluoroacetylacetonato. The extensive intramolecular H-bond is the cause for the segregation of the two entities but the supramolecular interactions between these two neutral building blocks resulted in a rare chiral co-crystal system. The directional properties of the supramolecular interactions,and F•••CH 2 , have been identified as working in tandem to generate the chirality from achiral components in achiral solvents. The absence of charge or proton transfer as suggested by X-ray structural analyses (bond lengths and angles), values of the magnetic moments, and lack of magnetic exchange between the metal spin and that of the organic radical are characteristics to define these two solids as genuine co-crystals. We therefore proposed that these solids be more effective as biomarkers than the pure radical. A comparison of their properties to related radicals is provided.

Impact of flexible succinate connectors on the formation of tetrasulfonylcalix[4]arene based nano-sized polynuclear cages: structural diversity and induced chirality study

“…The formation of chiral nanosized cages based on calixarene and on tetrasulfonylcalix[4]arene has been scarcely reported in the literature: one example for the formation of octahedral M24 cages has been provided 53 and for the formation of M8 cages examples have been reported stating from a chiral ditopic ligand. 57 Although the case of induced chirality in the crystalline state, starting from achiral compounds has been well documented in the literature, 65,66,67 this work presents the first example of the formation of chiral crystalline coordination compounds resulting from the H-bonding between the two different components: metal-calixarene based nanocontainers and M II (DMF)4(OH)2 neutral species.…”

Synthesis, crystal structures, and magnetic properties of nitroxide radical-coordinated manganese(II) and cobalt(II) complexes

“…The procedure for the synthesis of Co(hfac) 2 ·2H 2 O was the same as that used for except that Co(CH 3 COO) 2 ·H 2 O. FTIR 42 (KBr, cm −1 ): 3367 (s), 1645 (s), 1563 (s), 1536 (s), 1488 (s), 1236 (s), 1144 (s), 806 (s), 746 (w), 676 (s), 590 (s).…”

“…The light blue solid was dried at 50 °C for 3 days to give Mn(hfac) 2 •2H 2 O (0.74 g) was obtained. FTIR 42 (KBr, cm −1 ): 3398 (s), 1618 (s), 1561 (s), 1534 (s), 1497 (s), 1250 (s), 1212 (s), 800 (s), 767 (w), 743 (w), 667 (s), 590 (s).…”

“…The procedure for the synthesis of Co(hfac) 2 •2H 2 O was the same as that used for except that Co(CH 3 COO) 2 •H 2 O. FTIR 42…”

Supramolecular Co-assembly of the Ti8L12 Cube with [Ti(DMF)6] Species and Ti12-Oxo Cluster

“…Recently, crystalline titanium-oxo clusters have made significant progress in structural diversity, , bandgap regulation, host–guest exchange, fluorescence, and photocatalysis, , while the investigation on their supramolecular interaction is still rare. Furthermore, titanium-organic cages have also attracted wide attention on account of their structural aesthetics, intrinsic characteristics, and compelling supramolecular behaviors. − Co-crystallization is of great importance in crystal engineering and is extensively employed in the design and assembly of supramolecular materials, − which is exemplified in the formation to cocrystal of a giant (AgAu) 267 (SR) 80 nanoparticle with a much smaller (AgAu) 45 (SR) 27 (PPh 3 ) 6 cluster (SR = 2,4-SPhMe 2 ) and coexistence of the Eu 2 (L 2b R ) 3 helicate and tetrahedral Eu 4 (L 2b R ) 6 . , Therefore, the cocrystal assembly of titanium-organic cages with titanium-oxo clusters or other species may provide the possibility to gain further insight into their supramolecular behaviors and also the resulting photoactivities.…”