Metal ion-dependent molecular inclusion chemistry: inclusion of aromatic anions by coordinated 1,4,7,10-tetrakis((S)-2-hydroxy-3-phenoxypropyl)-1,4,7,10-tetraazacyclododecane.
The ability of the pendant donor macrocyclic ligand 1,4,7,10-tetrakis((S)-2-hydroxy-3-phenoxypropyl)-1,4,7,10-tetraaza- cyclododecane((S)-thphpc12) (or [Cd((S)-thphpc12)](2+)) to act as a metal ion-dependent receptor for aromatic anions has been investigated in solution and in the solid state. [Cd((S)-thphpc12)](2+) adopts a stable conical conformation with a large hydrophobic cavity, which has been shown to contain, via complementary multiple hydrogen bonding, p-nitrophenolate, aromatic carboxylates, p-toluenesulfonate, certain aromatic amino acid anions, phenoxyacetate, and acetate. In the case of p-nitrophenolate only, one or two anions can be contained within the receptor cavity. The crystal structure of [Cd((S)-thphpc12)(p-nitrophenolate)(2)] shows a coplanar arrangement of the p-nitrophenolates, where each is retained in the cavity by a pair of hydrogen bonds to cis hydroxyl groups. The crystal structure of the p-aminobenzoate inclusion complex indicates retention of the guest via a pair of hydrogen bonds to each oxygen atom of the carboxylate moiety. The crystal structure of the (L)-phenylalaninate inclusion complex indicates that the amino acid is retained by five hydrogen bonds, two involving the nitrogen atom and three to the oxygen atoms of the carboxylate moiety. Binding constants (10(3)-10(5) M(-1)) for the inclusion of some of the aforementioned anions in [Cd((S)-thphpc12)](2+) and related receptors were measured by (1)H NMR titration in DMSO-d(6) at 298 K.
Smith
Christopher B
CB
School of Chemistry, The Flinders University of South Australia, GPO Box 2100, Adelaide, SA 5001, Australia.
Stephens
Ashley K W
AK
Wallwork
Kia S
KS
Lincoln
Stephen F
SF
Taylor
Max R
MR
Wainwright
Kevin P
KP
D000596:Amino Acids / Q000138:chemical synthesis / Q000737:chemistry*; D001391:Azo Compounds / Q000737:chemistry*; D001555:Benzene Derivatives / Q000737:chemistry*; D001565:Benzoates / Q000138:chemical synthesis / Q000737:chemistry; D002104:Cadmium / Q000737:chemistry*; D002264:Carboxylic Acids / Q000138:chemical synthesis / Q000737:chemistry; D002413:Cations, Divalent / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D015394:Molecular Structure; D009281:Naphthalenes / Q000138:chemical synthesis / Q000737:chemistry; D009596:Nitrophenols / Q000737:chemistry; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010649:Phenylalanine / Q000138:chemical synthesis / Q000737:chemistry; D012459:Salicylates / Q000138:chemical synthesis / Q000737:chemistry; D013237:Stereoisomerism
C454379:1,4,7,10-tetrakis((S)-2-hydroxy-3-phenoxypropyl)-1,4,7,10-tetraazacyclododecane; D000596:Amino Acids; D001391:Azo Compounds; D001555:Benzene Derivatives; D001565:Benzoates; D002264:Carboxylic Acids; D002413:Cations, Divalent; D008024:Ligands; D009281:Naphthalenes; D009596:Nitrophenols; D009942:Organometallic Compounds; D012459:Salicylates; D002104:Cadmium; D010649:Phenylalanine