Title
Nanoconstruction of microspheres and microcapsules using proton-induced phase transitions: Molecular self-recognition by diamide diacids in water
Abbreviated Journal Title
Chem. Mat.
Keywords
AQUEOUS-SOLUTION; BUNDLE PROTEIN; HYDROGEN-BOND; PEPTIDE; CONFORMATION; MICROSCOPY; NANOTUBES; SEQUENCE; DESIGN; NMR; Chemistry, Physical; Materials Science, Multidisciplinary
Abstract
Bis(N-alpha-amido-L-phenylalanine)-1,1-cyclobutane dicarboxylate (5) was studied by Fourier transform infrared (FTIR) spectroscopy, variable-temperature NMR (VT-NMR), transmission electron microscopy, X-ray crystallography, Raman microscopy, and a novel imaging technique known as "soft" X-ray microscopy (XRM). Diamide diacid 5 was shown to self-associate into solid microspheres during a proton-induced phase transition from the solvated state to the desolvated assembled state. These diverse techniques allowed for the delineation of the molecular recognition events involved in the assembly process. X-ray crystallography revealed that 5 packs in a bundled helical array comprised of two types of intermolecular hydrogen bonds (i.e., OC=O . . . HN and COOH . . .O=CN). VT-NMR and IR measurements of 5 (1 mM in CDCl3) revealed the small temperature dependence of the amide NH chemical shift (Delta delta/DeltaT = -1.1 ppb/K) and the availability of the "free" amide NH of 5 to form intermolecular hydrogen bonds. Supramolecular rodlike structures were observed during the aqueous assembly of 5 into microspheres by XRM. Raman microscopy confirmed that nearly identical bonding patterns are present in the assembled microsphere and the crystal architecture of 5. Collectively, these observations provide compelling evidence that the assembly of 5 occurs via crystalline supramolecular intermediates, which are similar in shape and have complementary bonding motifs for proper self-recognition. Competition experiments involving varying concentrations of 5 and its microcapsule-forming cyclopropane analogue 3 revealed that molecular fidelity was less important to the microsphere-forming process than the related capsule-forming process.
Journal Title
Chemistry of Materials
Volume
13
Issue/Number
2
Publication Date
1-1-2001
Document Type
Article
DOI Link
Language
English
First Page
264
Last Page
272
WOS Identifier
ISSN
0897-4756
Recommended Citation
"Nanoconstruction of microspheres and microcapsules using proton-induced phase transitions: Molecular self-recognition by diamide diacids in water" (2001). Faculty Bibliography 2000s. 8156.
https://stars.library.ucf.edu/facultybib2000/8156