Tetrahedral Recognition of a Water Molecule by Heteroditopic Cryptands:  X-ray Structural Studies

Laterally non-symmetric aza cryptand molecules stitched by water

“…1 The mode of binding of water molecules with L viewed along the threefold axis of the cryptand As a result, only one strand of the cryptand molecule is present in the asymmetric unit. The bond distances and bond angles (Table 3) are within normal statistical errors and compares [3] well with the corresponding distances found in L.…”

“…It has been observed earlier that the cryptand L crystallizes [3] from an organic solvent such as acetone or acetonitrile without any association among the cryptand molecules. However, it is obvious that the secondary amines present in the three strands of L can potentially act as hydrogen-bond 0.37052(7) 0.12948 (7) 0.87052 (7) 0.0188 (5) N2 0.18179(7) 0.31821 (7) 0.68179 (7) 0.0190 (5) N3 0.16773(7) 0.16166 (7) 0.69593 (7) (8) (Fig.…”

“…The cryptand L was synthesized as reported [3] previously. Compound L·4H 2 O (1) was synthesized by dissolving 1 g of L in 5 ml of aqueous acetone (1:1) in presence of diethyl amine (5 ml) and allowing to evaporate at room temperature.…”

Complexation Properties of Heteroditopic Cryptands towards Cu2+, Zn2+, Cd2+, and Pb2+ in Aqueous Solution: Crystal Structures of [(H5L1)(ClO4)5]·4 H2O and [(NiL2Cl)Cl]·5.5 H2O·CH3OH

“…This can often be attributed to the presence of solvent molecules in the cavity, which contribute to the stabilities of the protonated species through hydrogen bonding. [23,28,30] As a matter of fact, as shown by recent crystal structures, H 2 L1 2ϩ and H 2 L2 2ϩ are able to bind one [30] and two [23] water molecules, respectively, forming significant hydrogen-bond networks within the cavity involving the ammonium groups. In [(H 2 L1)ʚH 2 O] 2ϩ , the water molecule seems to be bound more strongly than in the H 2 L2 2ϩ cryptate due to the direct participation of both the binding moieties in the former.…”

Selective and efficient tripodal receptors for competitive solvent extraction and bulk liquid membrane transport of Hg2+

“…2-Aminoethanol, N,N-dimethylethane-1,2-diamine and 2-amino methyl pyridine were purchased from Aldrich Chemicals. 2,2 ,2 -(2,2 ,2 -Nitrilotris(ethane-2,1-diyl)tris(oxy))tribenzaldehyde (1) was prepared according to the method described previously [25]. Doubly distilled, deionized water was used throughout.…”