Molecular Imprinting Inside Dendrimers

• Published in: Journal of the American Chemical Society Vol. 125; no. 44; pp. 13504 - 13518
• Main Authors: Zimmerman, Steven C, Zharov, Ilya, Wendland, Michael S, Rakow, Neal A, Suslick, Kenneth S
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 05.11.2003; Amer Chemical Soc
• Subjects: Binding Sites; Chemistry; Chemistry, Multidisciplinary; Cross-Linking Reagents - chemistry; Exact sciences and technology; Kinetics; Miscellaneous; Organic chemistry; Physical Sciences; Polymers - chemistry; Porphyrins - chemistry; Reactivity and mechanisms; Science & Technology; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Spectrophotometry, Ultraviolet; Substrate Specificity; HOSTS; RING-CLOSING METATHESIS; RECOGNITION; OLEFIN METATHESIS; NETWORK POLYMERS; PORPHYRIN; SUPRAMOLECULAR CHEMISTRY; BINDING; METAL-COMPLEXES; CARBOXYLIC-ACIDS; Photometric titration; Nitrogen heterocycle; Supramolecular structure; Combinatorial chemistry; Experimental study; Molecular imprinting; Mass spectrometry; Non metal porphyrin; Dendritic structure
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja0357240

Synthetic hosts capable of binding porphyrins have been produced by a mixed-covalent-noncovalent imprinting process wherein a single binding site is created within cross-linked dendrimers. Two synthetic hosts were prepared, using as templates 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin and 5,10,15,20-tetrakis(3,5-dihydroxyphenyl)porphyrin. These two templates were esterified with, respectively, fourth- and third-generation Fréchet-type dendrons containing homoallyl end-groups. The resulting tetra- and octadendron macromolecules underwent the ring-closing metathesis reaction using Grubbs' Type I catalyst, RuCl2(P(C6H5)3)2(CHCH2C6H5), to give extensive interdendron cross-linking. Hydrolytic removal of the porphyrin cores afforded imprinted hosts whose ability to bind porphyrins with various peripheral substituents was investigated by UV−visible spectrophotometric titrations and size exclusion chromatography. The results indicate a high yield of imprinted sites that show high selectivity for binding of porphyrins capable of making at least four hydrogen bonds, but only a moderate degree of shape selectivity.