Structure modeling, synthesis and X-ray diffraction determination of an extra-large calixarene-based coordination cage and its application in drug delivery

• Published in: Dalton transactions : an international journal of inorganic chemistry Vol. 44; no. 32; pp. 14394 - 14402
• Main Authors: Du, Shangchao, Yu, Tang-Qing, Liao, Wuping, Hu, Chunhua
• Format: Journal Article
• Language: English
• Published: England 28.08.2015
• Subjects: Amorphous materials; Anti-Inflammatory Agents, Non-Steroidal - chemistry; Cage; Calixarenes - chemistry; Crystallography, X-Ray; Drug Delivery Systems; Ibuprofen; Ibuprofen - chemistry; Ligands; Models, Molecular; Molecular Structure; Symmetry; Synthesis; X-Ray Diffraction - methods; X-rays
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c5dt01526j

An extra-large octahedral coordination cage (CIAC-114) was designed and modeled based on Co4-p-tert-butylsulfonylcalix[4]arene (Co4-(SC4A-SO2)) subunits and 4,4',4''-(benzene-1,3,5-triyl-tris(benzene-4,1-diyl))tribenzoate (BBB) ligands via the isomorphic replacement approach built from an analogous cage structure with a smaller size. X-ray crystallography revealed that the crystals obtained through solvothermal synthesis exhibited the anticipated structure. Each CIAC-114 cage is assembled by six tetranuclear Co4-(SC4A-SO2) units as vertices, which bear a four-fold rotational symmetry, and eight tripodal BBB ligands as linkers, which hold a D3h symmetry. Among its analogues CIAC-114 has the largest overall peripheral diameter of 5.4 nm and an internal cavity of 2.7 nm. After treatment by supercritical CO2, a single crystal sample of CIAC-114 transformed into amorphous material with the retention of the cage skeleton, which demonstrated good adsorption properties towards a small drug molecule, ibuprofen (Ibu), evidenced by IR spectroscopy, (1)H NMR spectroscopy, N2 sorption analysis, and drug release experiments. The Ibu release experiment in phosphate buffered saline solution (pH = 7.4) revealed that CIAC-114 exhibited a slow drug release behavior.